Microsolvation of Mg2+, Ca2+: Strong influence of formal charges in hydrogen bond networks

A stochastic exploration of the quantum conformational spaces in the microsolvation of divalent cations with explicit consideration of up to six solvent molecules [Mg (H 2 O) n )]2+, (n = 3, 4, 5, 6) at the B3LYP, MP2, CCSD(T) levels is presented. We find several cases in which the formal charge in Mg2+ causes dissociation of water molecules in the first solvation shell, leaving a hydroxide ion available to interact with the central cation, the released proton being transferred to outer solvation shells in a Grotthus type mechanism; this particular finding sheds light on the capacity of Mg2+ to promote formation of hydroxide anions, a process necessary to regulate proton transfer in enzymes with exonuclease activity. Two distinct types of hydrogen bonds, scattered over a wide range of distances (1.35–2.15 Å) were identified. We find that in inner solvation shells, where hydrogen bond networks are severely disturbed, most of the interaction energies come from electrostatic and polarization+charge transfer, while in outer solvation shells the situation approximates that of pure water clusters

A model for microinstability destabilization and enhanced transport in the presence of shielded 3-D magnetic perturbations

A mechanism is presented that suggests shielded 3-D magnetic perturbations can destabilize microinstabilities and enhance the associated anomalous transport. Using local 3-D equilibrium theory, shaped tokamak equilibria with small 3-D deformations are constructed. In the vicinity of rational magnetic surfaces, the infinite-n ideal MHD ballooning stability boundary is strongly perturbed by the 3-D modulations of the local magnetic shear associated with the presence of nearresonant Pfirsch-Schluter currents. These currents are driven by 3-D components of the magnetic field spectrum even when there is no resonant radial component. The infinite-n ideal ballooning stability boundary is often used as a proxy for the onset of virulent kinetic ballooning modes (KBM) and associated stiff transport. These results suggest that the achievable pressure gradient may be lowered in the vicinity of low order rational surfaces when 3-D magnetic perturbations are applied. This mechanism may provide an explanation for the observed reduction in the peak pressure gradient at the top of the edge pedestal during experiments where edge localized modes have been completely suppressed by applied 3-D magnetic fields

Why ‘Good Governance’ Fails: Lessons from Regional Economic Development in Colombia

By critically reviewing different strands of literature on institutional change and development, this essay argues that, in order to fully understand subnational economic development, we need to move away from ‘good governance' explanations in which geography‐specific analyses of power structures and elite interests are largely absent. Using findings for Colombia and insights from economic geography and heterodox political economy theories, this essay gives theoretical and conceptual guidelines and approximations for future studies on regional economic development. The contribution provides a place‐based discussion of how the historically evolved distribution of power balances, context‐specific elite interests, and the interaction between place‐bound actors and place‐less dynamics affect subnational institutional arrangements shaping policies and development outcomes. The conclusions drawn are not limited to Colombia and will prove beneficial to researchers studying regional economic development in subnational contexts elsewhere in the world

BASS. XXX. Distribution functions of DR2 Eddington ratios, black hole masses, and X-ray luminosities

Galaxie

Burden and risk factors for Pseudomonas aeruginosa community-acquired pneumonia:a Multinational Point Prevalence Study of Hospitalised Patients

Pseudornonas aeruginosa is a challenging bacterium to treat due to its intrinsic resistance to the antibiotics used most frequently in patients with community-acquired pneumonia (CAP). Data about the global burden and risk factors associated with P. aeruginosa-CAP are limited. We assessed the multinational burden and specific risk factors associated with P. aeruginosa-CAP. We enrolled 3193 patients in 54 countries with confirmed diagnosis of CAP who underwent microbiological testing at admission. Prevalence was calculated according to the identification of P. aeruginosa. Logistic regression analysis was used to identify risk factors for antibiotic-susceptible and antibiotic-resistant P. aeruginosa-CAP. The prevalence of P. aeruginosa and antibiotic-resistant P. aeruginosa-CAP was 4.2% and 2.0%, respectively. The rate of P. aeruginosa CAP in patients with prior infection/colonisation due to P. aeruginosa and at least one of the three independently associated chronic lung diseases (i.e. tracheostomy, bronchiectasis and/or very severe chronic obstructive pulmonary disease) was 67%. In contrast, the rate of P. aeruginosa-CAP was 2% in patients without prior P. aeruginosa infection/colonisation and none of the selected chronic lung diseases. The multinational prevalence of P. aeruginosa-CAP is low. The risk factors identified in this study may guide healthcare professionals in deciding empirical antibiotic coverage for CAP patients

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Sediment transfers from the Andes of Colombia during the anthropocene

This chapter reviews data, models, and analyses on Anthropocene-impacted sediment fluxes in the Andes of Colombia and provides examples on how direct human alteration has increased sediment flux during the last decades. Firstly, it describes the context of the northern Andes in terms of sediment production within the whole Andes Cordillera. Secondly, it presents a summary of major land cover changes witnessed in the region from 8000 years ago to the beginning of large-scale land transformation that occurred in Colombia during the last three decades and analyzes major human-induced drivers of change. Also, trends in sediment load during the 1980–2010 period are documented. Finally, it compares modern and prehuman conditions of sediment flux by using some applied models in global and Colombian rivers. An inventory of per capita anthropogenic land cover change (ALCC) from 8 ka toAD 2000 for the Andes of Colombia reveals that a nearly pristine environment existed until 3 ka. Two thousand years later, byAD 1, ALCC only slightly increases. FromAD 1500 toAD 1600, the ALCC scenarios show a decrease in anthropogenic land use in the Andes, as the indigenous populations of the Americas succumbed to disease and war brought by European explorers and colonists. The collapse of large precontact populations with advanced agriculture, which were especially concentrated in Mesoamerica and the Andes, led to high amounts of land abandonment. The low levels of ALCC shown atAD 1500 are almost entirely abandoned 100 years after conquest. ByAD 1687, anthropogenic land use in the Andes accelerated with the spread of colonies and nations founded by Europeans. The Americas only start to result in substantial amounts of ALCC emissions during the last centuries. Further studies on historical patterns and drivers of landscape change in Colombia since 1500 confirm that land conversion in the Andes started five centuries ago. The transformed area in the Andean region rose from 15 M ha in 1500 to 42 M ha in 2000. During the last two centuries, the annual rate of forest-transformed area increased two orders of magnitude, from 4330 ha y-1 in 1800 to 171,190 ha y-1 in 2000. By the year 2000, 80% of the natural vegetation in the Andes was cleared, with 20% remaining as scattered remnants. An assumed value of 30% was cleared in preconquest agricultural landscapes (before 1500), increasing to 80% in 2000. Demographic impacts of colonization and the introduction of cattle were major drivers of change. Findings of land use and sediment load trends indicate that the extent of erosion within the Andes of Colombia has severely increased over the last 30 years. For example, the last decade has been a period of increased pulses in sediment transport and rates of deforestation as seen by the statistical significant trends in load and by a marked increase of 241% in forest clearance. As a whole, the Andean drainage basins have witnessed an increase in erosion rates of 33%, from 550 t km-2 y-1 before 2000 to 710 t km-2 y-1 for the 2000–2010 period. Levels of sediment transport are one order of magnitude higher in modern times than during prehuman conditions. The differences between prehuman and modern sediment load in South American rivers were more pronounced for the Magdalena River, with a difference ranging between -100 and -150 Mt. y-1. Thus, during pristine conditions and according to the observed total load of the Magdalena, 184 Mt. y-1, the Magdalena could have had an annual sediment load between 34 and 84 Mt. y-1 during prehuman times. Further results indicate that 35% of the sediment load in the Colombian Andes is due to deforestation; 1690 Mt. of sediments were produced due to forest clearance over the last three decades. Much of the river catchments (79%) are under severe erosional conditions due in part to the clearance of more than 80% natural forest during the last 500 years. © Springer Nature Switzerland AG 2019

Sediment load trends in the Magdalena River basin (1980–2010): Anthropogenic and climate-induced causes

The Colombian Andes and its main river basin, the Magdalena, have witnessed dramatic changes in land cover and further forest loss during the last three decades. For the Magdalena River, human activities appear to have played a more prominent role compared to rainfall (climate change) to mobilize sediment. However, environmental authorities in Colombia argue that climate change is the main trigger of erosion and floods experienced during the last decade. Here we present the first regional exercise addressing the following: (1) what are the observed trends of sediment load in the northern Andes during the last three decades? and (2) are sediment load trends in agreement with tendencies in land use change and climate (e.g., precipitation)? We perform Mann-Kendall tests on sediment load series for 21 main tributary systems during the 1980–2010 period. These gauging stations represent 77% of the whole Magdalena basin area. The last decade has been a period of increased pulses in sediment transport as seen by the statistical significant trends in load. Overall, six subcatchments, representing 55% of the analyzed Magdalena basin area, have witnessed increasing trends in sediment load. Also, some major tributaries have experienced changes in their interannual mean sediment flux during the mid- 1990s and 2005. Further analysis of land cover change (e.g., deforestation) indicates that the basin has undergone considerable change. Forest cover decreased by 40% over the period of study, while the area under agriculture and pasture cover (agricultural lands 1 and 2) increased by 65%. The highest peak of forest loss on record in the Magdalena basin, 5106 km2 or 24% of the combined deforestation in Colombia, occurred during the 2005-2010 period. In contrast, Mann-Kendall tests on rainfall series for 61 stations reveal that precipitation shows no regional signs of increasing trends. Also, increasing trends in sediment load match quite well with the marked increase in forest clearance during the 1990–2000 and 2005–2010 periods. Such signs of increasing sediment fluxes should not be attributed to climate change and rainfall variability alone. As a whole, the Magdalena, one of the top 10 rivers in terms of sediment delivery to the ocean (184 Mt y- 1), and its tributaries have experienced increasing trends in sediment load during the 1980–2010 period; increases in close agreement with trends in land use change and deforestation. During the last decade, the Magdalena River drainage basin has witnessed an increase in erosion rates of 34%, from 550 t km- 2 y- 1 before 2000 to 710 t km- 2 y- 1 for the 2000–2010 period, and the average sediment load for the whole basin increased to 44 Mt y- 1 for the same period. Similar to the global picture of human contribution to sediment generation, the rate of anthropogenic soil erosion in the Magdalena basin probably exceeds the rate of climate-driven erosion by several orders of magnitude. © 2016 Elsevier B.V