Impact of HPA nonlinearity on MIMO systems with quantized equal gain transmission

In this paper, we investigate the performance of multiple-input multiple-output (MIMO) transmit beamforming (TB) systems in the presence of nonlinear high-power amplifiers (HPAs). Due to the suboptimality of maximal ratio transmission/maximal ratio combining (MRT/MRC) under HPA nonlinearity, quantized equal gain transmission (QEGT) is suggested as a feasible TB scheme. The effect of HPA nonlinearity on the performance of MIMO QEGT/MRC is evaluated in terms of the average symbol error probability (SEP) and system capacity, considering transmission over uncorrelated quasi-static frequency-flat Rayleigh fading channels. Numerical results are provided and show the effects of several system parameters, such as the parameters of nonlinear HPA, cardinality of the beamforming weight vector codebook, and modulation order of quadrature amplitude modulation (QAM), on performance.

Systematic study of the impact of fresh water fluxes on the glacial carbon cycle

During glacial periods, atmospheric CO2 concentration increases and decreases by around 15 ppm. At the same time, the climate changes gradually in Antarctica. Such climate changes can be simulated in models when the AMOC (Atlantic Meridional Oceanic Circulation) is weakened by adding fresh water to the North Atlantic. The impact on the carbon cycle is less straightforward, and previous studies give opposite results. Because the models and the fresh water fluxes were different in these studies, it prevents any direct comparison and hinders finding whether the discrepancies arise from using different models or different fresh water fluxes. In this study we use the CLIMBER-2 coupled climate carbon model to explore the impact of different fresh water fluxes. In both preindustrial and glacial states, the addition of fresh water and the resulting slow-down of the AMOC lead to an uptake of carbon by the ocean and a release by the terrestrial biosphere. The duration, shape and amplitude of the fresh water flux all have an impact on the change of atmospheric CO2 because they modulate the change of the AMOC. The maximum CO2 change linearly depends on the time integral of the AMOC change. The different duration, amplitude, and shape of the fresh water flux cannot explain the opposite evolution of ocean and vegetation carbon inventory in different models. The different CO2 evolution thus depends on the AMOC response to the addition of fresh water and the resulting climatic change, which are both model dependent. In CLIMBER-2, the rise of CO2 recorded in ice cores during abrupt events can be simulated under glacial conditions, especially when the sinking of brines in the Southern Ocean is taken into account. The addition of fresh water in the Southern Hemisphere leads to a decline of CO2, contrary to the addition of fresh water in the Northern Hemisphere.

Building post crisis watchtowers: investment management Systems and new institutional logics for regulatory compliance

The financial crisis of 2007-2009 has precipitated large scale regulatory change. Tight deadlines for implementation require organizations to start working on remediation projects before final drafts of regulations are crystalized. Firms are faced with engaging in complex and costly change management programs at a time when profits are diminished. As a consequence of these factors, pre-crisis logics for organizing compliance practices are being questioned and new approaches introduced. Our study explores the use of Investment Management Systems (IMS) in facilitating compliance arrangements. Our motivation is to understand the new logics and the part played by IMS in supporting these approaches. The study adopts an institutional logics perspective to explore the use of such systems at eight financial organizations. The study found new logics for organizing compliance include consolidation, centralization, harmonization and consistency and that the IMS plays an important role in supporting and enabling related activities.

Accounting information systems as institutional carriers: a case study of regulatory compliance in UK asset management houses

Previously, governments have responded to the impacts of economic failures and consequently have developed more regulations to protect employees, customers, shareholders and the economic wellbeing of the state. Our research addresses how Accounting Information Systems (AIS) may act as carriers for institutionalised practices associated with maintaining regulatory compliance within the context of UK Asset Management Houses. The AIS was found to be a strong conduit for institutionalized compliance related practices, utilising symbolic systems, relational systems, routines and artefacts to carry approaches relating to regulative, normative and cultural-cognitive strands of institutionalism. Thus, AIS are integral to the development and dissipation of best practice for the management of regulatory compliance. As institutional elements are clearly present we argue that AIS and regulatory compliance provide a rich context to further institutionalism. Since AIS may act as conduits for regulatory approaches, both systems adopters and clients may benefit from actively seeking to codify and abstract best practices into AIS. However, the application of generic institutionalized approaches, which may be applied across similar organizations, must be tempered with each firm’s business environment and associated regulatory exposure. A balance should be sought between approaches specific enough to be useful but generic enough to be universally applied.

Information architecture for healthcare organizations: the case of a NHS Hospital in UK

Healthcare organizations are known for their complex and intense information environment. Healthcare information is facilitated via heterogeneous information systems or paper-based sources. Access to the right information under increasing time pressure is extremely challenging. This paper proposes an information architecture for healthcare organizations. It facilitates the provision of the right information to the right person in the right place and time tailored to their requirements. It adapts an abductive reasoning research approach. Organizational semiotics serves as its theoretical underpinning, guiding the data collection process through direct observation in the ophthalmology outpatient clinics of a UK hospital. It results the norm and information objects that form the information architecture. This is modeled by Archimate. The contribution of the information architecture can be seen from organizational, social and technical perspective. It clearly shows how information is facilitated within a healthcare organization, reducing duplicated data entry, and guiding the future technological implementation.

The potential impact of changes in lower stratospheric water vapour on stratospheric temperatures over the past 30 years

This study investigates the potential contribution of observed changes in lower stratospheric water vapour to stratospheric temperature variations over the past three decades using a comprehensive global climate model (GCM). Three case studies are considered. In the first, the net increase in stratospheric water vapour (SWV) from 1980–2010 (derived from the Boulder frost-point hygrometer record using the gross assumption that this is globally representative) is estimated to have cooled the lower stratosphere by up to ∼0.2 K decade−1 in the global and annual mean; this is ∼40% of the observed cooling trend over this period. In the Arctic winter stratosphere there is a dynamical response to the increase in SWV, with enhanced polar cooling of 0.6 K decade−1 at 50 hPa and warming of 0.5 K decade−1 at 1 hPa. In the second case study, the observed decrease in tropical lower stratospheric water vapour after the year 2000 (imposed in the GCM as a simplified representation of the observed changes derived from satellite data) is estimated to have caused a relative increase in tropical lower stratospheric temperatures by ∼0.3 K at 50 hPa. In the third case study, the wintertime dehydration in the Antarctic stratospheric polar vortex (again using a simplified representation of the changes seen in a satellite dataset) is estimated to cause a relative warming of the Southern Hemisphere polar stratosphere by up to 1 K at 100 hPa from July–October. This is accompanied by a weakening of the westerly winds on the poleward flank of the stratospheric jet by up to 1.5 m s−1 in the GCM. The results show that, if the measurements are representative of global variations, SWV should be considered as important a driver of transient and long-term variations in lower stratospheric temperature over the past 30 years as increases in long-lived greenhouse gases and stratospheric ozone depletion.

Multimodel assessment of water scarcity under climate change

Water scarcity severely impairs food security and economic prosperity in many countries today. Expected future population changes will, in many countries as well as globally, increase the pressure on available water resources. On the supply side, renewable water resources will be affected by projected changes in precipitation patterns, temperature, and other climate variables. Here we use a large ensemble of global hydrological models (GHMs) forced by five global climate models and the latest greenhouse-gas concentration scenarios (Representative Concentration Pathways) to synthesize the current knowledge about climate change impacts on water resources. We show that climate change is likely to exacerbate regional and global water scarcity considerably. In particular, the ensemble average projects that a global warming of 2 degrees C above present (approximately 2.7 degrees C above preindustrial) will confront an additional approximate 15% of the global population with a severe decrease in water resources and will increase the number of people living under absolute water scarcity (< 500 m(3) per capita per year) by another 40% (according to some models, more than 100%) compared with the effect of population growth alone. For some indicators of moderate impacts, the steepest increase is seen between the present day and 2 degrees C, whereas indicators of very severe impacts increase unabated beyond 2 degrees C. At the same time, the study highlights large uncertainties associated with these estimates, with both global climate models and GHMs contributing to the spread. GHM uncertainty is particularly dominant in many regions affected by declining water resources, suggesting a high potential for improved water resource projections through hydrological model development.

Predicting solar disturbance effects on navigation systems

A variety of operational systems are vulnerable to disruption by solar disturbances brought to the Earth by the solar wind. Of particular importance to navigation systems are energetic charged particles which can generate temporary malfunctions and permanent damage in satellites. Modern spacecraft technology may prove to be particularly at risk during the next maximum of the solar cycle. In addition, the associated ionospheric disturbances cause phase shifts of transionospheric and ionosphere-reflected signals, giving positioning errors and loss of signal for GPS and Loran-C positioning systems and for over-the-horizon radars. We now have sufficient understanding of the solar wind, and how it interacts with the Earth's magnetic field, to predict statistically the likely effects on operational systems over the next solar cycle. We also have a number of advanced ways of detecting and tracking these disturbances through space but we cannot, as yet, provide accurate forecasts of individual disturbances that could be used to protect satellites and to correct errors. In addition, we have recently discovered long-term changes in the Sun, which mean that the number and severity of the disturbances to operational systems are increasing.

Effects of water availability on free amino acids, sugars, and acrylamide-forming potential in potato

Irrigation is used frequently in potato cultivation to maximize yield, but water availability may also affect the composition of the crop, with implications for processing properties and food safety. Five varieties of potatoes, including drought-tolerant and -sensitive types, which had been grown with and without irrigation, were analyzed to show the effect of water supply on concentrations of free asparagine, other free amino acids, and sugars and on the acrylamide-forming potential of the tubers. Two varieties were also analyzed under more severe drought stress in a glasshouse. Water availability had profound effects on tuber free amino acid and sugar concentrations, and it was concluded that potato farmers should irrigate only if necessary to maintain the health and yield of the crop, because irrigation may increase the acrylamide-forming potential of potatoes. Even mild drought stress caused significant changes in composition, but these differed from those caused by more extreme drought stress. Free proline concentration, for example, increased in the field-grown potatoes of one variety from 7.02 mmol/kg with irrigation to 104.58 mmol/kg without irrigation, whereas free asparagine concentration was not affected significantly in the field but almost doubled from 132.03 to 242.26 mmol/kg in response to more severe drought stress in the glasshouse. Furthermore, the different genotypes were affected in dissimilar fashion by the same treatment, indicating that there is no single, unifying potato tuber drought stress response.

Effect of high temperature and water stress on groundnuts under field conditions

Groundnuts cultivated in the semiarid tropics are often exposed to water stress (mid-season and end season) and high temperature (> 34 °C) during the critical stages of flowering and pod development. This study evaluated the effects of both water stress and high temperature under field conditions at ICRISAT, India. Treatments included two irrigations (full irrigation, 100 % of crop evapotranspiration; and water stress, 40 % of crop evapotranspiration), four temperature treatments from a combination of two sowing dates and heat tunnels with mean temperatures from sowing to maturity of 26.3° (T1), 27.3° (T2), 29.0° (T3) and 29.7 °C (T4) and two genotypes TMV2 and ICGS 11. The heat tunnels were capable of raising the day temperature by > 10 °C compared to ambient. During the 20-day high-temperature treatment at flowering, mean temperatures were 33.8° (T1), 41.6° (T2), 38.7° (T3) and 43.5°C (T4). The effects of water stress and high temperature were additive and temporary for both vegetative and pod yield, and disappeared as soon as high-temperature stress was removed. Water use efficiency was significantly affected by the main effects of temperature and cultivar and not by water stress treatments. Genotypic differences for tolerance to high temperature can be attributed to differences in flowering pattern, flower number, peg-set and harvest index. It can be inferred from this study that genotypes that are tolerant to water stress are also tolerant to high temperature under field conditions. In addition, genotypes with an ability to establish greater biomass and with a significantly greater partitioning of biomass to pod yield would be suitable for sustaining higher yields in semiarid tropics with high temperature and water stress.

Impact of the Arctic Ocean Atlantic water layer on Siberian shelf hydrography

This paper examines the role of the Arctic Ocean Atlantic water (AW) in modifying the Laptev Sea shelf bottom hydrography on the basis of historical records from 1932 to 2008, field observations carried out in April–May 2008, and 2002–2009 cross‐slope measurements. A climatology of bottom hydrography demonstrates warming that extends offshore from the 30–50 m depth contour. Bottom layer temperature‐time series constructed from historical records links the Laptev Sea outer shelf to the AW boundary current transporting warm and saline water from the North Atlantic. The AW warming of the mid‐1990s and the mid‐2000s is consistent with outer shelf bottom temperature variability. For April–May 2008 we observed on‐shelf near‐bottom warm and saline water intrusions up to the 20 m isobath. These intrusions are typically about 0.2°C warmer and 1–1.5 practical salinity units saltier than ambient water. The 2002–2009 cross‐slope observations are suggestive for the continental slope upward heat flux from the AW to the overlying low‐halocline water (LHW). The lateral on‐shelf wind‐driven transport of the LHW then results in the bottom layer thermohaline anomalies recorded over the Laptev Sea shelf. We also found that polynya‐induced vertical mixing may act as a drainage of the bottom layer, permitting a relatively small portion of the AW heat to be directly released to the atmosphere. Finally, we see no significant warming (up until now) over the Laptev Sea shelf deeper than 10–15 m in the historical record. Future climate change, however, may bring more intrusions of Atlantic‐modified waters with potentially warmer temperature onto the shelf, which could have a critical impact on the stability of offshore submarine permafrost.

Interacting effects of change in climate, human population, land use, and water use on biodiversity and ecosystem services

Human population growth and resource use, mediated by changes in climate, land use, and water use, increasingly impact biodiversity and ecosystem services provision. However, impacts of these drivers on biodiversity and ecosystem services are rarely analyzed simultaneously and remain largely unknown. An emerging question is how science can improve the understanding of change in biodiversity and ecosystem service delivery and of potential feedback mechanisms of adaptive governance. We analyzed past and future change in drivers in south-central Sweden. We used the analysis to identify main research challenges and outline important research tasks. Since the 19th century, our study area has experienced substantial and interlinked changes; a 1.6°C temperature increase, rapid population growth, urbanization, and massive changes in land use and water use. Considerable future changes are also projected until the mid-21st century. However, little is known about the impacts on biodiversity and ecosystem services so far, and this in turn hampers future projections of such effects. Therefore, we urge scientists to explore interdisciplinary approaches designed to investigate change in multiple drivers, underlying mechanisms, and interactions over time, including assessment and analysis of matching-scale data from several disciplines. Such a perspective is needed for science to contribute to adaptive governance by constantly improving the understanding of linked change complexities and their impacts.

Modelling water adsorption on Au(210) surfaces: II. Monte Carlo simulations

Canonical Monte Carlo simulations for the Au(210)/H(2)O interface, using a force field recently proposed by us, are reported. The results exhibit the main features normally observed in simulations of water molecules in contact with different noble metal surfaces. The calculations also assess the influence of the surface topography on the structural aspects of the adsorbed water and on the distribution of the water molecules in the direction normal to the metal surface plane. The adsorption process is preferential at sites in the first layer of the metal. The analysis of the density profiles and dipole moment distributions points to two predominant orientations. Most of the molecules are adsorbed with the molecular plane parallel to surface, while others adsorb with one of the O-H bonds parallel to the surface and the other bond pointing towards the bulk liquid phase. There is also evidence of hydrogen bond formation between the first and second solvent layers at the interface. (c) 2007 Elsevier B.V. All rights reserved.