Assessment of the Water Balance of European Forests: A Model Study

As part of the UN-ECE Intensive Monitoring Program, data on precipitation, throughfall and soil solution concentrations are measured on a regular basis in approximately 300 forest stands. These data were used to construct element budgets for European forests. To construct such budgets drainage fluxes have to be modeled. In this paper, the research chain from model selection to data derivation and application of the selected model to 245 of the 300 sites is described. To select a suitable hydrological model the Cl^- balance method, two capacity models (a multi and a single layer version) and a Darcy model have been applied to two forest sites. The results indicate that drainage fluxes calculated with the Darcy model are more accurate than fluxes derived with the capacity model, in particular in situations where water availability is limited. The Darcy model was applied to the sites using a mixture of generic data and site data. Despite the use of generic data, the calculated drainage fluxes appear feasible. Median transpiration fluxes were 350 mm and the lowest values are found in northern Europe and highest values are found in central Europe. Median drainage fluxes were 150 mm yr^-1 with the highest values in areas with high rainfall. Uncertainty analyses indicate that the use of local instead of interpolated meteorological data leads to lower drainage fluxes at 70% of the sites. The median deviation in calculated drainage fluxes is 20 mm yr^-1. The use of local soil data had little impact on the calculated fluxes.     

Partial amniotic carbon dioxide insufflation for fetal surgery

Partial amniotic carbon dioxide insufflation (PACI) involves insufflating the amniotic sac with carbon dioxide (CO₂) and, in some cases, draining some of the amniotic fluid. The creation of a gaseous intra-amniotic compartment improves visualization, even in the presence of limited bleeding, and creates the work space required for complex fetoscopic procedures. Clinically, PACI is mostly used to perform fetoscopic myelomeningocele (MMC) repair, enabling a minimally invasive alternative to open fetal surgery. However, evidence of the fetal safety of PACI is limited. Previous animal experiments in sheep demonstrate that PACI induces fetal hypercapnia and acidosis with largely unknown short and longer term implications. In this review, we examine the literature for the physiological effects of intrauterine insufflation pressure, duration, humidity, and the role of maternal hyperventilation on fetal physiology and well-being.     

Oxygen isotope fractionation between bird bone phosphate and drinking water

Oxygen isotope compositions of bone phosphate (δ¹⁸O_p) were measured in broiler chickens reared in 21 farms worldwide characterized by contrasted latitudes and local climates. These sedentary birds were raised during an approximately 3 to 4-month period, and local precipitation was the ultimate source of their drinking water. This sampling strategy allowed the relationship to be determined between the bone phosphate δ¹⁸O_p values (from 9.8 to 22.5‰ V-SMOW) and the local rainfall δ¹⁸O_w values estimated from nearby IAEA/WMO stations (from ?16.0 to ?1.0‰ V-SMOW). Linear least square fitting of data provided the following isotopic fractionation equation: δ¹⁸O_w = 1.119 (±0.040) δ¹⁸O_p ? 24.222 (±0.644); R ² = 0.98. The δ¹⁸O_p–δ¹⁸O_w couples of five extant mallard ducks, a common buzzard, a European herring gull, a common ostrich, and a greater rhea fall within the predicted range of the equation, indicating that the relationship established for extant chickens can also be applied to birds of various ecologies and body masses. Applied to published oxygen isotope compositions of Miocene and Pliocene penguins from Peru, this new equation computes estimates of local seawater similar to those previously calculated. Applied to the basal bird Confuciusornis from the Early Cretaceous of Northeastern China, our equation gives a slightly higher δ¹⁸O_w value compared to the previously estimated one, possibly as a result of lower body temperature. These data indicate that caution should be exercised when the relationship estimated for modern birds is applied to their basal counterparts that likely had a metabolism intermediate between that of their theropod dinosaur ancestors and that of advanced ornithurines.     

Was endothermy in amniotes induced by an early stop in growth during ontogeny?

Endothermy and its evolution are still an unresolved issue. Here, we present a model which transforms an ectothermic amniote (ancestor) into a derived amniote (descendant) showing many characteristics seen in extant endothermic birds and mammals. Consistent with the fossil record within the ancestral lineages of birds and mammals, the model assumes that mutations in genes which get active during ontogeny and affect body growth resulted in a reduced asymptotic body size and an early growth stop of the descendant. We show that such a postulated early growth stop in the descendant simultaneously increases the growth rate and metabolic rate, and also changes six life history traits (offspring mass, annual clutch/litter mass, number of offspring per year, age and mass at which sexual maturity is reached, age at which the individual is fully grown) of the descendant compared to a similar-sized ancestor. All these changes coincide with known differences between recent ectothermic and endothermic amniotes. We also elaborate many other differences and similarities in biological characteristics supporting the early growth stop. An early stop in growth during ontogeny thus could have played a key role in the evolution of endothermy within the reptilia and therapsids. It generated variability in characteristics of ancestral ectotherms, which was subject to natural selection in the past and resulted in many adaptations linked to endothermy in today’s birds and mammals.     

Multilevel learning from accidents – Case studies in transport

Substantial efforts have been devoted to accident investigations, but do we gain a reasonable benefit from these efforts? The current study explores multilevel (individual, company, sector/trade, authorities) learning from major accidents and serious incidents. Specifically, this involves identifying a set of learning criteria, i.e. factors or indicators that potentially support and contribute to multilevel learning processes. Identifying such criteria is based on: (i) the accident investigation process, (ii) the follow-up efforts, and (iii) contextual aspects. Three Norwegian accident investigations in transportation (aviation, marine, rail) represent the empirical foundation for the study. Learning criteria were derived by both document analyses from the accidents (e.g. investigation reports) and literature reviews on organizational learning. These were the basis for a workshop regarding learning from accidents, with participants from the aviation, marine, and rail sector. Key results from this workshop are presented and discussed. The study concludes by presenting a set of criteria for learning from accidents.     

Thermogravimetric pyrolysis of waste polyethylene-terephthalate and polystyrene: A critical assessment of kinetics modelling

Pyrolysis is considered as possible technique to thermally convert waste plastics into chemicals and energy. Literature on experimental findings is extensive, although experiments are mostly performed in a dynamic heating mode, using thermogravimetric analysis (TGA) and at low values of the heating rate (mostly below 30 K/min). The present research differs from literature through the application of far higher heating rates, up to 120 K/min. The use of these dynamic results to define the reaction kinetics necessitates the selection of an appropriate reaction mechanism, and 21 models have been proposed in literature considering the rate limiting step being diffusion, nucleation or the reaction itself.The current research studied the cracking of PET and PS by TGA at different heating rates (temperature ramps). Results were used to check the validity of the proposed mechanisms. Several conclusions are drawn: (i) to obtain fair results, the heating ramp should exceed a minimum value, calculated at 30 K/min for PET and 80 K/min for PS; (ii) application of the majority of the models to experimental findings demonstrated that they do not meet fundamental kinetic considerations and are questionable in their use; and (iii) simple models, with reaction order 1 or 2, provide similar results of the reaction activation energy.A further comparison with literature data for dynamic and isothermal experiments confirms the validity of these selected models. Since TGA results are obtained on a limited amount of sample, with results being a strong function of the applied heating rate, the authors believe that isothermal experiments, preferably on a large scale both towards equipment and/or sample size, are to be preferred.     

Stage-specific biomass overcompensation by juveniles in response to increased adult mortality in a wild fish population

Recently developed theoretical models of stage-structured consumer-resource systems have shown that stage-specific biomass overcompensation can arise in response to increased mortality rates. We parameterized a stage-structured population model to simulate the effects of increased adult mortality caused by a pathogen outbreak in the perch (Perca fluviatilis) population of Windermere (UK) in 1976. The model predicts biomass overcompensation by juveniles in response to increased adult mortality due to a shift in food-dependent growth and reproduction rates. Considering cannibalism between life stages in the model reinforces this compensatory response due to the release from predation on juveniles at high mortality rates. These model predictions are matched by our analysis of a 60-year time series of scientific monitoring of Windermere perch, which shows that the pathogen outbreak induced a strong decrease in adult biomass and a corresponding increase in juvenile biomass. Age-specific adult fecundity and size at age were higher after than before the disease outbreak, suggesting that the pathogen-induced mortality released adult perch from competition, thereby increasing somatic and reproductive growth. Higher juvenile survival after the pathogen outbreak due to a release from cannibalism likely contributed to the observed biomass overcompensation. Our findings have general implications for predicting population- and community-level responses to increased size-selective mortality caused by exploitation or disease outbreaks.