Exchange processes between stratosphere and troposphere

Imperial Users onl

Productivity pathways: climate-adjusted production frontiers for the Australian broadacre cropping industry

This study introduces two advances to the aggregate productivity index methodology typically employed by ABARES. First, it accounts for the effects of climate variability on measured productivity by matching spatial climate data to individual farms in the ABARES farm surveys database. Second, a farm-level production frontier estimation technique is employed to facilitate the decomposition of productivity change into several key components, including technical change and technical efficiency change. The study makes use of farm-level data from the ABARES Australian agricultural and grazing industries survey database. An unbalanced panel dataset is constructed containing 13 430 observations (4255 farms) over the period 1977–78 to 2007–08. Spatial climate data, including winter and summer seasonal rainfall and average maximum and minimum temperatures, were obtained via the Australian Water Availability Project. These data were mapped to individual farms using Geographic Information System methods. The study employed stochastic frontier analysis methods to estimate a production frontier with time varying technical efficiency effects of the form proposed by Battese and Coelli (1992). Production frontiers are estimated for each of the three major Grains Research and Development Corporation regions: southern, northern and western. Selected climate variables are shown to display a high degree of explanatory power over farm output. The results confirm that deterioration in average climate conditions has contributed significantly to the decline in estimated productivity over the post-2000 period. Technical change is shown to be the primary driver of productivity growth in the industry in the long run, offset by a gradual decline in technical efficiency. After controlling for climate variability, a gradual decline in the rate of technical change is still observed.Productivity Analysis,

‘The glory of ruling makes all things permissible’: power and usurpation in Byzantium: some aspects of communication, legitimacy, and moral authority

In Byzantium, usurpation was made possible by the conflict between hereditary-dynastic and meritocratic-republican theories of rulership. Legitimacy was founded upon subjective notions of idealized moral-behavioural norms drawn from the imperial virtues and Christian ideology. Authority could be challenged when it was perceived to deviate from these norms. Investitures transformed a usurper from a private individual to an emperor on the basis of ratification by popular consent. The historic ritual of reluctance allowed emperors to present themselves as ‘moral ideals’ at the moment of proclamation, ridding them of blame for a usurpation. Guilt and sin were inevitable byproducts of usurpation, but imperial repentance facilitated an expiation and legitimized imperial authority in relation to moral ideals. On occasion a usurper’s successors would perform repentance on his behalf, freeing the dynasty from the sins of its foundation. The treatment of defeated usurpers could take a variety of forms: reconciliations enabled a peaceful ‘healing’ of the community. Political mutilations transformed the victim’s appearance and rendered him ‘other’ in an attempt to demonstrate his immorality and illegitimacy. Degradation parades inverted recognised investiture rites in order to permanently alter a victim’s identity and reveal him to be a tyrant, acting against the interests of the people

Near-wall modeling of forests for atmosphere boundary layers using lattice Boltzmann method on GPU

In this paper, the simulation and modeling of the turbulent atmospheric boundary layers (ABLs) in the presence of forests are studied using a lattice Boltzmann method with large eddy simulation, which was implemented in the open-source program GASCANS with the use of Graphic Processing Units (GPU). A method of modeling forests in the form of body forces injected near the wall is revisited, while the effects of leaf area density (LAD) on the model accuracy is further addressed. Since a uniform cell size is applied throughout the computational domain, the wall-normal height of the near-wall cells is very large, theoretically requiring a wall function to model the boundary layer. However, the wall function is disregarded here when the forest is modeled. This approximation is validated based on the comparison with previous experimental and numerical data. It concludes that for the ABL conditions specified in this study as well as a large body of literature, the forest forces overwhelm the wall friction so that the modeling of the latter effect is trivial. Constant and varying LAD profiles across the forest zone are defined with the same total leaf area despite the varying one being studied previously. It is found that the two LAD profiles provide consistent predictions. The present forest modeling can therefore be simplified with the use of the constant LAD without degrading the model accuracy remarkably

Male disadvantage?:Fetal sex and cardiovascular responses to asphyxia in preterm fetal sheep

Clinically and experimentally male fetuses are at significantly greater risk of dying or suffering injury at birth, particularly after premature delivery. We undertook a retrospective cohort analysis of 60 female and 65 male singleton preterm fetal sheep (103-104 days, 0.7 gestation) with mean arterial blood pressure (MAP), heart rate, and carotid and femoral blood flow recordings during 25 min of umbilical cord occlusion in utero. Occlusions were stopped early if fetal MAP fell below 8 mmHg or if there was asystole for >20 s. Fetuses that were able to complete the full 25-min period of occlusion showed no differences between sexes for any cardiovascular responses. Similar numbers of occlusions were stopped early in males (mean: 21 min, n = 16) and females (mean: 23 min, n = 16); however, they showed different responses. Short-occlusion males (n = 16) showed a slower initial fall in femoral vascular conductance, followed by greater bradycardia, hypotension, and associated organ hypoperfusion compared with full-occlusion fetuses. In contrast, short-occlusion females (n = 16) showed a significantly more rapid early increase in femoral vascular conductance than the full-occlusion fetuses, followed by worsening of bradycardia and hypotension that was intermediate to the full-occlusion fetuses and short-occlusion males. Among all fetuses, MAP at 15 min of occlusion, corresponding with the time of the maximal rate of fall, was correlated with postmortem weight in males (R(2) = 0.07) but not females. In conclusion, male and female fetuses showed remarkably similar chemoreflex and hemodynamic responses to severe asphyxia, but some males did show impaired hemodynamic adaptation within the normal weight range

SOLITAIRE:A new generation solenoidal fusion product separator

A superconducting solenoidal fusion product separator, based on a 6.5 T solenoid, has been developed at the Australian National University to enable separation and detection of evaporation residues following heavy-ion fusion reactions. This device, with an angular coverage of 0.45 - 9 . 5{ring operator}, produces a spatial separation between the fusion products and the intense background of elastically scattered beam particles. Its high efficiency allows precise measurement of nuclear fusion cross-sections, as well as being ideal for evaporation residue coincidence measurements. The essential features of the system and the first results obtained are described

农业贸易改革——有利于澳大利亚大面积农业的改革措施

澳大利亚的农业高度依赖于世界市场。澳大利亚相当部分的农产品是用于出口的，其农产品价格时刻反映世界市场的价格。全球农业政策的根本改革将会使世界市场的扭曲减少，在世界范围内提高农产品价格并为澳大利亚农民提供更多的贸易机会。虽然WTO多哈回合中农业谈判的进展日渐缓慢，但谈判仍给扭曲农业贸易的根本性的政策改革提供了机会。由于澳大利亚的农业高度依赖于世界市场，这样的改革将会为澳大利亚的农民带来经济利益。例如凯恩斯集团所提出的改革会使农产品市场的扭曲减少，澳大利亚农业的门槛价格提高，农民的现金收入增加及土地价格上涨。译者单位：厦门大学国际经济与贸易系(361005

Triage Considerations for Patients Referred for Structural Heart Disease Intervention During the Coronavirus Disease 2019 (COVID-19) Pandemic: An ACC /SCAI Consensus Statement

The COVID-19 pandemic has strained health care resources around the world causing many institutions to curtail or stop elective procedures. This has resulted in the inability to care for patients valvular and structural heart disease (SHD) in a timely fashion potentially placing these patients at increased risk for adverse cardiovascular complications including congestive heart failure and death. The effective triage of these patients has become challenging in the current environment as clinicians have had to weigh the risk of bringing susceptible patients into the hospital environment during the COVID-19 pandemic versus the risk of delaying a needed procedure. In this document, we suggest guidelines as to how to triage patients in need of SHD interventions and provide a framework of how to decide when it may be appropriate to proceed with intervention despite the ongoing pandemic. In particular, we address the triage of patients in need of trans-catheter aortic valve replacement and percutaneous mitral valve repair. We also address procedural issues and considerations for the function of structural heart disease teams during the COVID-19 pandemic

Triage Considerations for Patients Referred for Structural Heart Disease Intervention During the COVID-19 Pandemic: An ACC/SCAI Position Statement

The coronavirus disease-2019 (COVID-19) pandemic has strained health care resources around the world, causing many institutions to curtail or stop elective procedures. This has resulted in an inability to care for patients with valvular and structural heart disease in a timely fashion, potentially placing these patients at increased risk for adverse cardiovascular complications, including CHF and death. The effective triage of these patients has become challenging in the current environment as clinicians have had to weigh the risk of bringing susceptible patients into the hospital environment during the COVID-19 pandemic against the risk of delaying a needed procedure. In this document, the authors suggest guidelines for how to triage patients in need of structural heart disease interventions and provide a framework for how to decide when it may be appropriate to proceed with intervention despite the ongoing pandemic. In particular, the authors address the triage of patients in need of transcatheter aortic valve replacement and percutaneous mitral valve repair. The authors also address procedural issues and considerations for the function of structural heart disease teams during the COVID-19 pandemic