Statistics for the Evaluation and Comparison of Models

Copyright 1985 by the American Geophysical Union.Procedures that may be used to evaluate the operational performance of a wide spectrum of geophysical models are introduced. Primarily using a complementary set of difference measures, both model accuracy and precision can be meaningfully estimated, regardless of whether the model predictions are manifesteda s scalars,d irections,o r vectors.I t is additionally suggestedth at the reliability of the accuracy and precision measures can be determined from bootstrap estimates of confidence and significance. Recommendedp roceduresa re illustrated with a comparativee valuation of two models that estimate wind velocity over the South Atlantic Bight

Defining and measuring displacement: is relocation from restructured neighbourhoods always unwelcome and disruptive?

Current regeneration policy has been described as ‘state-led gentrification’, with comparisons made with the ‘social disruption’ caused by slum clearance of the 1950s and 1960s. This article takes issue with this approach in relation to the study of the restructuring of social housing areas. The terms ‘forced relocation’ and ‘displacement’ are often too crude to describe what actually happens within processes of restructuring and the effects upon residents. Displacement in particular has important dimensions other than the physical one of moving. Evidence from a recent study of people who have moved out of restructured areas shows that although there is some evidence of physical displacement, there is little evidence of social or psychosocial displacement after relocation. Prior attitudes to moving and aspects of the process of relocation—the degree of choice and distance involved—are important moderators of the outcomes. Issues of time and context are insufficiently taken into consideration in studies and accounts of restructuring, relocation and displacement

Understanding the rapid summer warming and changes in temperature extremes since the mid-1990s over Western Europe

Analysis of observations indicates that there was a rapid increase in summer (June-August, JJA) mean surface air temperature (SAT) since the mid-1990s over Western Europe. Accompanying this rapid warming are significant increases in summer mean daily maximum temperature, daily minimum temperature, annual hottest day temperature and warmest night temperature, and an increase in frequency of summer days and tropical nights, while the change in the diurnal temperature range (DTR) is small. This study focuses on understanding causes of the rapid summer warming and associated temperature extreme changes. A set of experiments using the atmospheric component of the state-of-the-art HadGEM3 global climate model have been carried out to quantify relative roles of changes in sea surface temperature (SST)/sea ice extent (SIE), anthropogenic greenhouse gases (GHGs), and anthropogenic aerosols (AAer). Results indicate that the model forced by changes in all forcings reproduces many of the observed changes since the mid-1990s over Western Europe. Changes in SST/SIE explain 62.2% ± 13.0% of the area averaged seasonal mean warming signal over Western Europe, with the remaining 37.8% ± 13.6% of the warming explained by the direct impact of changes in GHGs and AAer. Results further indicate that the direct impact of the reduction of AAer precursor emissions over Europe, mainly through aerosol-radiation interaction with additional contributions from aerosol-cloud interaction and coupled atmosphere-land surface feedbacks, is a key factor for increases in annual hottest day temperature and in frequency of summer days. It explains 45.5% ± 17.6% and 40.9% ± 18.4% of area averaged signals for these temperature extremes. The direct impact of the reduction of AAer precursor emissions over Europe acts to increase DTR locally, but the change in DTR is countered by the direct impact of GHGs forcing. In the next few decades, greenhouse gas concentrations will continue to rise and AAer precursor emissions over Europe and North America will continue to decline. Our results suggest that the changes in summer seasonal mean SAT and temperature extremes over Western Europe since the mid-1990s are most likely to be sustained or amplified in the near term, unless other factors intervene

Transient anhedonia phenotype and altered circadian timing of behaviour during night-time dim light exposure in Per3(-/-) mice, but not wildtype mice.

Industrialisation greatly increased human night-time exposure to artificial light, which in animal models is a known cause of depressive phenotypes. Whilst many of these phenotypes are 'direct' effects of light on affect, an 'indirect' pathway via altered sleep-wake timing has been suggested. We have previously shown that the Period3 gene, which forms part of the biological clock, is associated with altered sleep-wake patterns in response to light. Here, we show that both wild-type and Per3(-/-) mice showed elevated levels of circulating corticosterone and increased hippocampal Bdnf expression after 3 weeks of exposure to dim light at night, but only mice deficient for the PERIOD3 protein (Per3(-/-)) exhibited a transient anhedonia-like phenotype, observed as reduced sucrose preference, in weeks 2-3 of dim light at night, whereas WT mice did not. Per3(-/-) mice also exhibited a significantly smaller delay in behavioural timing than WT mice during weeks 1, 2 and 4 of dim light at night exposure. When treated with imipramine, neither Per3(-/-) nor WT mice exhibited an anhedonia-like phenotype, and neither genotypes exhibited a delay in behavioural timing in responses to dLAN. While the association between both Per3(-/-) phenotypes remains unclear, both are alleviated by imipramine treatment during dim night-time light

Evapotranspiration model comparison and an estimate of field scale Miscanthus canopy precipitation interception

The bioenergy crop Miscanthus x giganteus has a high water demand to quickly increase biomass with rapid canopy closure and effective rainfall interception, traits that are likely to impact on hydrology in land use change. Evapotranspiration (ET, the combination of plant and ground surface transpiration and evaporation) forms an important part of the water balance and few ET models have been tested with Miscanthus. Therefore this study uses field measurements to determine the most accurate ET model and to establish the interception of precipitation by the canopy (Ci). Daily ET estimates from 2012 to 2016 using the Hargreaves-Samani, Priestley-Taylor, Granger-Gray and Penman-Monteith (short grass) models were calculated using data from a weather station situated in a 6 ha Miscanthus crop. Results from these models were compared to data from on-site eddy covariance (EC) instrumentation to determine accuracy and calculate the crop coefficient (Kc) model parameter. Ci was measured from June 2016 to March 2017 using stem-flow and through-flow gauges within the crop and rain gauges outside the crop. The closest estimated ET to the EC data was the Penman-Monteith (short grass) model. The Kc values proposed are 0.63 for the early season (March and April), 0.85 for the main growing season (May to September), 1.57 for the late growing season (October and November), and 1.12 over the winter (December to February). These more accurate Kc values will enable better ET estimates with the use of the Penman-Monteith (short grass) model improving estimates of potential yields and hydrological impacts of land use change. Ci was 24 % and remained high during the autumn and winter thereby sustaining significant levels of canopy evaporation and suggesting benefits for winter flood mitigation.publishersversionPeer reviewe

Non-linear Autoregressive Neural Networks to Forecast Short-Term Solar Radiation for Photovoltaic Energy Predictions

Nowadays, green energy is considered as a viable solution to hinder CO2 emissions and greenhouse effects. Indeed, it is expected that Renewable Energy Sources (RES) will cover 40% of the total energy request by 2040. This will move forward decentralized and cooperative power distribution systems also called smart grids. Among RES, solar energy will play a crucial role. However, reliable models and tools are needed to forecast and estimate with a good accuracy the renewable energy production in short-term time periods. These tools will unlock new services for smart grid management. In this paper, we propose an innovative methodology for implementing two different non-linear autoregressive neural networks to forecast Global Horizontal Solar Irradiance (GHI) in short-term time periods (i.e. from future 15 to 120min). Both neural networks have been implemented, trained and validated exploiting a dataset consisting of four years of solar radiation values collected by a real weather station. We also present the experimental results discussing and comparing the accuracy of both neural networks. Then, the resulting GHI forecast is given as input to a Photovoltaic simulator to predict energy production in short-term time periods. Finally, we present the results of this Photovoltaic energy estimation discussing also their accuracy

Rapid interhemispheric climate links via the Australasian monsoon during the last deglaciation

Recent studies have proposed that millennial-scale reorganization of the ocean-atmosphere circulation drives increased upwelling in the Southern Ocean, leading to rising atmospheric carbon dioxide levels and ice age terminations. Southward migration of the global monsoon is thought to link the hemispheres during deglaciation, but vital evidence from the southern sector of the vast Australasian monsoon system is yet to emerge. Here we present a 230thorium-dated stalagmite oxygen isotope record of millennial-scale changes in Australian–Indonesian monsoon rainfall over the last 31,000 years. The record shows that abrupt southward shifts of the Australian–Indonesian monsoon were synchronous with North Atlantic cold intervals 17,600–11,500 years ago. The most prominent southward shift occurred in lock-step with Heinrich Stadial 1 (17,600–14,600 years ago), and rising atmospheric carbon dioxide. Our findings show that millennial-scale climate change was transmitted rapidly across Australasia and lend support to the idea that the 3,000-year-long Heinrich 1 interval could have been critical in driving the last deglaciation

Formation of a morphine-conditioned place preference does not change the size of evoked potentials in the ventral hippocampus–nucleus accumbens projection

Abstract In opioid addiction, cues and contexts associated with drug reward can be powerful triggers for drug craving and relapse. The synapses linking ventral hippocampal outputs to medium spiny neurons of the accumbens may be key sites for the formation and storage of associations between place or context and reward, both drug-related and natural. To assess this, we implanted rats with electrodes in the accumbens shell to record synaptic potentials evoked by electrical stimulation of the ventral hippocampus, as well as continuous local-field-potential activity. Rats then underwent morphine-induced (10 mg/kg) conditioned-place-preference training, followed by extinction. Morphine caused an acute increase in the slope and amplitude of accumbens evoked responses, but no long-term changes were evident after conditioning or extinction of the place preference, suggesting that the formation of this type of memory does not lead to a net change in synaptic strength in the ventral hippocampal output to the accumbens. However, analysis of the local field potential revealed a marked sensitization of theta- and high-gamma-frequency activity with repeated morphine administration. This phenomenon may be linked to the behavioral changes—such as psychomotor sensitization and the development of drug craving—that are associated with chronic use of addictive drugs

The sperm factor: paternal impact beyond genes

The fact that sperm carry more than the paternal DNA has only been discovered just over a decade ago. With this discovery, the idea that the paternal condition may have direct implications for the fitness of the offspring had to be revisited. While this idea is still highly debated, empirical evidence for paternal effects is accumulating. Male condition not only affects male fertility but also offspring early development and performance later in life. Several factors have been identified as possible carriers of non-genetic information, but we still know little about their origin and function and even less about their causation. I consider four possible non-mutually exclusive adaptive and non-adaptive explanations for the existence of paternal effects in an evolutionary context. In addition, I provide a brief overview of the main non-genetic components found in sperm including DNA methylation, chromatin modifications, RNAs and proteins. I discuss their putative functions and present currently available examples for their role in transferring non-genetic information from the father to the offspring. Finally, I identify some of the most important open questions and present possible future research avenues