Comparison of exergy found by a classical thermodynamic approach and by the use of the information stored in the genome

It is possible to calculate the exergy for organisms based on classic thermodynamics as already demonstrated by Mejer and Jorgensen [Mejer, H., Jorgensen, S.E., 1979. Exergy and ecological buffer capacity. State-of-the-art in Ecol. Model. 7, 829–846]. The calculation of exergy as eco-exergy, which is based on the information stored in the genome, has lately been proposed by Jørgensen and co-workers. Recently, Ludovisi [Ludovisi, A., 2009. Exergy vs information in ecological successions: interpreting community changes by a classical thermodynamic approach. Ecol. Model. 220, 1566–1577] has put forward a method based on classical thermodynamics, which leads to the calculation of “virtual” values of concentration at equilibrium for a number of organic compounds (VEC) and freshwater organisms (VECE). This paper compares the two approaches by analysing the correlation existing between the VECE- and the β-values derived by Jørgensen et al. [Jørgensen, S.E., Ladegaard, N., Debeljak, M., Marques, J.C., 2005. Calculations of exergy for organisms. Ecol. Model. 185, 165–175]. It was found that there was a good correlation, which can be useful for estimating β-values for organisms whose genome is not known in a sufficient detail. The relationship between VECE- and β-values suggests that two proposed thermodynamic orientors based on these quantities – the eco-exergy index and the structural information – should lead to coherent results when applied to the evaluation of the development state of ecosystems. A numerical simulation shows that this expectation is verified in a major case, but also that different, even opposite, responses can arise, depending on the biological composition of the biocoenosis investigated.     

Stormwater treatment: examples of computational fluid dynamics modeling

Control of rainfall-runoff particulate matter (PM) and PM-bound chemical loads is challenging; in part due to the wide gradation of PM complex geometries of many unit operations and variable flow rates. Such challenges and the expense associated with resolving such challenges have led to the relatively common examination of a spectrum of unit operations and processes. This study applies the principles of computational fluid dynamics (CFD) to predict the particle and pollutant clarification behavior of these systems subject to dilute multiphase flows, typical of rainfall-runoff, within computationally reasonable limits, to a scientifically acceptable degree of accuracy. The Navier-Stokes (NS) system of nonlinear partial differential equations for multiphase hydrodynamics and separation of entrained particles are solved numerically over the unit operation control volume with the boundary and initial conditions defined and then solved numerically until the desired convergence criteria are met. Flow rates examined are scaled based on sizing of common unit operations such as hydrodynamic separators (HS), wet basins, or filters, and are examined from 1 to 100 percent of the system maximum hydraulic operating flow rate. A standard turbulence model is used to resolve flow, and a discrete phase model (DPM) is utilized to examine the particle clarification response. CFD results closely follow physical model results across the entire range of flow rates. Post-processing the CFD predictions provides an in-depth insight into the mechanistic behavior of unit operations by means of three dimensional (3-D) hydraulic profiles and particle trajectories. Results demonstrate the role of scour in the rapid degradation of unit operations that are not maintained. Comparisons are provided between measured and CFD modeled results and a mass balance error is identified. CFD is arguably the most powerful tool available for our profession since continuous simulation modeling.     

Almost royal: incomplete suppression of host worker ovarian development by a social parasite wasp

Insect social parasites, like other parasites, may benefit from inhibiting their host from reproducing (complete or partial parasitic castration) because they can then exploit more of the host’s resources for their own reproduction. In particular, social parasites that kill or expel the host queen need to prevent host workers from reproducing; this is a common worker response to the absence of their queen. Indeed, host workers would benefit from detecting the presence of the parasite and investing in direct and indirect fitness. Studying whether and how social parasites control host worker reproduction can provide information about the degree of integration of the parasite in the host colony and help identify factors regulating workers’ reproductive decisions in social insects. We investigated whether the paper wasp social parasite, Polistes sulcifer, suppresses Polistes dominula (host) worker reproduction as efficiently as the dominant host female does in queen-right colonies by comparing worker reproductive efforts in parasitized and non-parasitized (control) colonies. Our results show that 6 weeks after usurpation of their colony by the social parasite, parasitized workers (1) had more developed ovaries than control workers and (2) laid more eggs as soon as the opportunity arose. This reproductive readiness of parasitized workers was not apparent 2 weeks after colony usurpation. This suggests that P. dominula workers have evolved means to react to social parasitism, as occurs in some ants, and that the parasite has only limited control over host reproduction.     

Setting up an early warning system for epidemic-prone diseases in Darfur: a participative approach

In April-May 2004, the World Health Organization (WHO) implemented, with local authorities, United Nations (UN) agencies and non-governmental organisations (NGOs), an early warning system (EWS) in Darfur, West Sudan, for internally displaced persons (IDPs). The number of consultations and deaths per week for 12 health events is recorded for two age groups (less than five years and five years and above). Thresholds are used to detect potential outbreaks. Ten weeks after the introduction of the system, NGOs were covering 54 camps, and 924,281 people (IDPs and the host population). Of these 54 camps, 41 (76%) were reporting regularly under the EWS. Between 22 May and 30 July, 179,795 consultations were reported: 18.7% for acute respiratory infections; 15% for malaria; 8.4% for bloody diarrhoea; and 1% for severe acute malnutrition. The EWS is useful for detecting outbreaks and monitoring the number of consultations required to trigger actions, but not for estimating mortality.     

Sex identification in female crayfish is bimodal

Sex identification has been studied in several species of crustacean decapods but only seldom was the role of multimodality investigated in a systematic fashion. Here, we analyse the effect of single/combined chemical and visual stimuli on the ability of the crayfish Procambarus clarkii to identify the sex of a conspecific during mating interactions. Our results show that crayfish respond to the offered stimuli depending on their sex. While males rely on olfaction alone for sex identification, females require the combination of olfaction and vision to do so. In the latter, chemical and visual stimuli act as non-redundant signal components that possibly enhance the female ability to discriminate potential mates in the crowded social context experienced during mating period. This is one of the few clear examples in invertebrates of non-redundancy in a bimodal communication system.     

Detectability of the Eurasian otter by standard surveys: an approach using marking intensity to estimate false negative rates

False negative detections may bias the surveys for rare species and reduce the reliability of models based on the proportion of occupied patches. We assessed the detectability of the Eurasian otter Lutra lutra through the standard survey method by analysing the detection history of 28 sampling stretches surveyed monthly between March 2001 and January 2003. Each survey negative for otter spraints was considered as a false negative if the otter had been recorded in the previous and/or following month (respectively, cFN and FN). Otter marking intensity (MI) (MI=N° of spraints per kilometre) was calculated and assumed to represent an index of its relative abundance. Spraints were found in 81.7% of all surveys. Yearly MI ranged from 1.02 to 101.4 spraints per kilometre. In 2002, mean MI was significantly lower than in the previous year, while no clear seasonal trend could be outlined. The minimum number of surveys required to establish the occurrence of the otter, as estimated by a probability model, was 2.6 and was inversely related to MI. For a sub-sample of 18 sampling stretches, the relation between the frequency of both cFN and FN and five variables of potential interest for otters was tested by means of stepwise linear multiple regressions, yielding two highly significant models, which both included only MI as the explanatory variable. The frequency of both FN and cFN was correlated to MI and the resulting equations used to assess the percentage of surveys positive for otters in both years. After the correction for non-detections, otter site occupancy did not vary between the 2 years, except for one river when applying the more conservative estimate of false negatives (cFN). Multiple visits and the assessing of MI should become standard components of otter surveys. This approach has broad applicability and may be applied to assess the large-scale distribution of other rare or elusive mammalian carnivores.     

Molecular signatures of organic particulates as tracers of emission sources

Chemical signature of airborne particulates and deposition dusts is subject of study since decades. Usually, three complementary composition markers are investigated, namely, (i) specific organic compounds; (ii) concentration ratios between congeners, and (iii) percent distributions of homologs. Due to its intrinsic limits (e.g., variability depending on decomposition and gas/particle equilibrium), the identification of pollution sources based on molecular signatures results overall restricted to qualitative purposes. Nevertheless, chemical fingerprints allow drawing preliminary information, suitable for successfully approaching multivariate analysis and valuing the relative importance of sources. Here, the state-of-the-art is presented about the molecular fingerprints of non-polar aliphatic, polyaromatic (PAHs, nitro-PAHs), and polar (fatty acids, organic halides, polysaccharides) compounds in emissions. Special concern was addressed to alkenes and alkanes with carbon numbers ranging from 12 to 23 and?≥?24, which displayed distinct relative abundances in petrol-derived spills and exhausts, emissions from microorganisms, high vegetation, and sediments. Long-chain alkanes associated with tobacco smoke were characterized by a peculiar iso/anteiso/normal homolog fingerprint and by n-hentriacontane percentages higher than elsewhere. Several concentration ratios of PAHs were identified as diagnostic of the type of emission, and the sources of uncertainty were elucidated. Despite extensive investigations conducted so far, the origin of uncommon molecular fingerprints, e.g., alkane/alkene relationships in deposition dusts and airborne particles, remains quite unclear. Polar organics resulted scarcely investigated for pollution apportioning purposes, though they looked as indicative of the nature of sources. Finally, the role of humans and living organisms as actual emitters of chemicals seems to need concern in the future.

     

Sources and trends of trace elements and polycyclic aromatic hydrocarbons in a shallow lake in the Mediterranean area from sediment archives of the Anthropocene

Environmental Science and Pollution Research - In this study, the anthropogenic contamination in Trasimeno lake (Central Italy) was investigated using three sediment cores spanning over the last...     

Modeling and forecasting daily maximum hourly ozone concentrations using the RegAR model with skewed and heavy-tailed innovations

This paper considers the modeling and forecasting of daily maximum hourly ozone concentrations in Laranjeiras, Serra, Brazil, through dynamic regression models. In order to take into account the natural skewness and heavy-tailness of the data, a linear regression model with autoregressive errors and innovations following a member of the family of scale mixture of skew-normal distributions was considered. Pollutants and meteorological variables were considered as predictors, along with some deterministic factors, namely week-days and seasons. The Oceanic Niño Index was also considered as a predictor. The estimated model was able to explain satisfactorily well the correlation structure of the ozone time series. An out-of-sample forecast study was also performed. The skew-normal and skew-t models displayed quite competitive point forecasts compared to the similar model with gaussian innovations. On the other hand, in terms of forecast intervals, the skewed models presented much better performance with more accurate prediction intervals. These findings were empirically corroborated by a forecast Monte Carlo experiment.