Semi-parametric statistical approaches for space-time process prediction

The problem of estimation and prediction of a spatial-temporal stochastic process, observed at regular times and irregularly in space, is considered. A mixed formulation involving a non- parametric component, accounting for a deterministic trend and the effect of exogenous variables, and a parametric component representing the purely spatio-temporal random variation is proposed. Correspondingly, a two-step procedure, first addressing the estimation of the non- parametric component, and then the estimation of the parametric component is developed from the residual series obtained, with spatial-temporal prediction being performed in terms of suitable spatial interpolation of the temporal variation structure. The proposed model formula-tion, together with the estimation and prediction procedure, are applied using a Gaussian ARMA structure for temporal modelling to space-time forecasting from real data of air pollution concentration levels in the region surrounding a power station in northwest Spain.     

Conservation resource allocation,small population resiliency,and the fallacy of conservation triage

Some conservation prioritization methods are based on the assumption that conservation needs overwhelm current resources and not all species can be conserved; therefore, a conservation triage scheme (i.e., when the system is overwhelmed, species should be divided into three groups based on likelihood of survival, and efforts should be focused on those species in the group with the best survival prospects and reduced or denied to those in the group with no survival prospects and to those in the group not needing special efforts for their conservation) is necessary to guide resource allocation. We argue that this decision-making strategy is not appropriate because resources are not as limited as often assumed, and it is not evident that there are species that cannot be conserved. Small population size alone, for example, does not doom a species to extinction; plants, reptiles, birds, and mammals offer examples. Although resources dedicated to conserving all threatened species are insufficient at present, the world's economic resources are vast, and greater resources could be dedicated toward species conservation. The political framework for species conservation has improved, with initiatives such as the UN Sustainable Development Goals and other international agreements, funding mechanisms such as The Global Environment Facility, and the rise of many nongovernmental organizations with nimble, rapid-response small grants programs. For a prioritization system to allow no extinctions, zero extinctions must be an explicit goal of the system. Extinction is not inevitable, and should not be acceptable. A goal of no human-induced extinctions is imperative given the irreversibility of species loss.     

Quantitative alterations in the structure of the digestive cell of Littorina littorea on exposure to cadmium

The effects of sublethal concentrations of cadmium (Cd) on the morphology of the digestive gland of the periwinkle Littorina littorea have been investigated using a planimetric procedure. Five planimetric parameters were recorded (mean epithelial thickness: MET; mean diverticular radius: MDR; mean luminal radius: MLR; MLR/MET and MET/MDR) and tested by diverse statistical methods. The results indicate that MET is depressed after long exposures at high Cd concentrations whilst MLR increases. Variations in MDR have been attributed to different conditions in the tissues surrounding digestive tubules, and are not-significant in relation to the treatment. However, certain increases might be significant due to the presence of parasites or hemocyte proliferation. The ratios MLR/MET and MET/MDR are highly sensitive, and can be expressed as statistical functions of metal concentration and exposure time. Combination of these five planimetric parameters is reliably indicative of the structural changes occurring in the digestive gland of molluscs under conditions of environmental stress.     

A state-space model approach to optimum spatial sampling design based on entropy

We consider the spatial sampling design problem for a random field X. This random field is in general assumed not to be directly observable, but sample information from a related variable Y is available. Our purpose in this paper is to present a state-space model approach to network design based on Shannon's definition of entropy, and describe its main points with regard to some of the most common practical problems in spatial sampling design. For applications, an adaptation of Ko et al.'s (1995) algorithm for maximum entropy sampling in this context is provided. We illustrate the methodology using piezometric data from the Velez aquifer (Malaga, Spain). © Rapid Science 1998     

Model-driven development of covariances for spatiotemporal environmental health assessment

Known conceptual and technical limitations of mainstream environmental health data analysis have directed research to new avenues. The goal is to deal more efficiently with the inherent uncertainty and composite space-time heterogeneity of key attributes, account for multi-sourced knowledge bases (health models, survey data, empirical relationships etc.), and generate more accurate predictions across space-time. Based on a versatile, knowledge synthesis methodological framework, we introduce new space-time covariance functions built by integrating epidemic propagation models and we apply them in the analysis of existing flu datasets. Within the knowledge synthesis framework, the Bayesian maximum entropy theory is our method of choice for the spatiotemporal prediction of the ratio of new infectives (RNI) for a case study of flu in France. The space-time analysis is based on observations during a period of 15 weeks in 1998–1999. We present general features of the proposed covariance functions, and use these functions to explore the composite space-time RNI dependency. We then implement the findings to generate sufficiently detailed and informative maps of the RNI patterns across space and time. The predicted distributions of RNI suggest substantive relationships in accordance with the typical physiographic and climatologic features of the country.     

Chemical-mineralogical characterization of C&D waste recycled aggregates from São Paulo, Brazil

This study presents a methodology for the characterization of construction and demolition (C&;D) waste recycled aggregates based on a combination of analytical techniques (X-ray fluorescence (XRF), soluble ions, semi-quantitative X-ray diffraction (XRD), thermogravimetric analysis (TGA-DTG) and hydrochloric acid (HCl) selective dissolution). These combined analytical techniques allow for the estimation of the amount of cement paste, its most important hydrated and carbonated phases, as well as the amount of clay and micas. Details of the methodology are presented here and the results of three representative C&;D samples taken from the São Paulo region in Brazil are discussed. Chemical compositions of mixed C&;D aggregate samples have mostly been influenced by particle size rather than the visual classification of C&;D into red or grey and geographical origin. The amount of measured soluble salts in C&;D aggregates (0.15–25.4 mm) is lower than the usual limits for mortar and concrete production. The content of porous cement paste in the C&;D aggregates is around 19.3% (w/w). However, this content is significantly lower than the 43% detected for the C&;D powders (<0.15 mm). The clay content of the powders was also high, potentially resulting from soil intermixed with the C&;D waste, as well as poorly burnt red ceramic. Since only about 50% of the measured CaO is combined with CO₂, the powders have potential use as raw materials for the cement industry.     

Economic costs of protecting islands from invasive alien species

Biological invasions represent a key threat to insular systems and have pronounced impacts across environments and economies. The ecological impacts have received substantial focus, but the socioeconomic impacts are poorly synthesized across spatial and temporal scales. We used the InvaCost database, the most comprehensive assessment of published economic costs of invasive species, to assess economic impacts on islands worldwide. We analyzed socioeconomic costs across differing expenditure types and examined temporal trends across islands that differ in their political geography—island nation states, overseas territories, and islands of continental countries. Over US$36 billion in total costs (including damages and management) has occurred on islands from 1965 to 2020 due to invasive species’ impacts. Nation states incurred the greatest total and management costs, and islands of continental countries incurred costs of similar magnitude, both far higher than those in overseas territories. Damage-loss costs were significantly lower, but with qualitatively similar patterns across differing political geographies. The predominance of management spending differs from the pattern found for most countries examined and suggests important knowledge gaps in the extent of many damage-related socioeconomic impacts. Nation states spent the greatest proportion of their gross domestic products countering these costs, at least 1 order of magnitude higher than other locations. Most costs were borne by authorities and stakeholders, demonstrating the key role of governmental and nongovernmental bodies in addressing island invasions. Temporal trends revealed cost increases across all island types, potentially reflecting efforts to tackle invasive species at larger, more socially complex scales. Nevertheless, the already high total economic costs of island invasions substantiate the role of biosecurity in reducing and preventing invasive species arrivals to reduce strains on limited financial resources and avoid threats to sustainable development goals.     

Individual and collective foraging decisions: a field study of worker recruitment in the gypsy ant <Emphasis Type="Italic">Aphaenogaster senilis</Emphasis>

In social insects, the decision to exploit a food source is made both at the individual (e.g., a worker collecting a food item) and colony level (e.g., several workers communicating the existence of a food patch). In group recruitment, the recruiter lays a temporary chemical trail while returning from the food source to the nest and returns to the food guiding a small group of nestmates. We studied how food characteristics influence the decision-making process of workers changing from individual retrieving to group recruitment in the gypsy ant Aphaenogaster senilis. We offered field colonies three types of prey: crickets (cooperatively transportable), shrimps (non-transportable), and different quantities of sesame seeds (individually transportable). Colonies used group recruitment to collect crickets and shrimps, as well as seeds when they were available in large piles, while small seed piles rarely led to recruitment. Foragers were able to “measure” food characteristics (quality, quantity, transportability), deciding whether or not to recruit, accordingly. Social integration of individual information about food emerged as a colony decision to initiate or to continue recruitment when the food patch was rich. In addition, group recruitment allowed a fast colony response over a wide thermal range (up to 45°C ground temperature). Therefore, by combining both advantages of social foraging (group recruitment) and thermal tolerance, A. senilis accurately exploited different types of food sources which procured an advantage against mass-recruiting and behaviorally dominant species such as Tapinoma nigerrimum and Lasius niger.     

Separability studies of construction and demolition waste recycled sand

The quality of recycled aggregates from construction and demolition waste (CDW) is strictly related to the content of porous and low strength phases, and specifically to the patches of cement that remain attached to the surface of natural aggregates. This phase increases water absorption and compromises the consistency and strength of concrete made from recycled aggregates. Mineral processing has been applied to CDW recycling to remove the patches of adhered cement paste on coarse recycled aggregates. The recycled fine fraction is usually disregarded due to its high content of porous phases despite representing around 50% of the total waste.This paper focus on laboratory mineral separability studies for removing particles with a high content of cement paste from natural fine aggregate particles (quartz/feldspars). The procedure achieved processing of CDW by tertiary impact crushing to produce sand, followed by sieving and density and magnetic separability studies. The attained results confirmed that both methods were effective in reducing cement paste content and producing significant mass recovery (80% for density concentration and 60% for magnetic separation). The production of recycled sand contributes to the sustainability of the construction environment by reducing both the consumption of raw materials and disposal of CDW, particularly in large Brazilian centers with a low quantity of sand and increasing costs of this material due to long transportation distances.