Pattern-oriented modeling of agent-based complex systems: lessons from ecology

Agent-based complex systems are dynamic networks of many interacting agents; examples include ecosystems, financial markets, and cities. The search for general principles underlying the internal organization of such systems often uses bottom-up simulation models such as cellular automata and agent-based models. No general framework for designing, testing, and analyzing bottom-up models has yet been established, but recent advances in ecological modeling have come together in a general strategy we call pattern-oriented modeling. This strategy provides a unifying framework for decoding the internal organization of agent-based complex systems and may lead toward unifying algorithmic theories of the relation between adaptive behavior and system complexity.     

Detection of anti-Leishmania infantum antibodies in sylvatic lagomorphs from an epidemic area of Madrid using the indirect immunofluorescence antibody test

An outbreak of human leishmaniosis was confirmed in the southwest of the province of Madrid, Spain, between July 2009 and December 2012. Incidence of Leishmania infection in dogs was unchanged in this period, prompting a search for alternative sylvatic infection reservoirs. We evaluated exposure to Leishmania in serum samples from animals in the area with an indirect immunofluorescence test (IFAT). Using promastigotes from six culture passages and a 1/25 threshold titer, we found anti-Leishmania infantum seroreactivity in 9.3% of cats (4 of 43), 45.7% of rabbits (16/35) and 74.1% of hares (63/85). Use of promastigotes from >10 in vitro passages resulted in a notably IFAT lower titer, suggesting antigenic changes during extended culture. Postmortem inspection of seropositive animals showed no clinical signs of infection. The results clearly suggest that asymptomatic hares were the main reservoir in the outbreak, and corroborate IFAT as a sensitive serological surveillance method to detect such cryptic Leishmania infections.     

Fishery indicators during a predictable aggregation of Atlantic sharpnose sharks Rhizoprionodon terraenovae in the southern Gulf of Mexico: An alternative to assess a heterogeneous data‐poor fishery

Small‐scale fisheries in the southern Gulf of Mexico that catch Rhizoprionodon terraenovae (Richardson) are heterogeneous and data‐poor. Fishery‐dependent monitoring was conducted from 2010 to 2017, including a target season during an aggregation of this species to estimate data‐poor fishery indicators. During the target season, the average sizes for females and males (95.3 and 89.8 cm total length, respectively) were recorded, a global male sex bias (1:1.7), the highest percentage of mature sharks for all years (>89%), the highest values of CPUE (20.1 sharks/day) and size‐selectivity higher than the size at maturity. The spawning potential ratio was over 0.6 (reference point of 0.71) in the combined (target and non‐target) and target seasons for all years, which suggests that the fishery stock is not healthy. Annual assessment of this fishery can be carried out through monitoring during the target season, where management is more feasible to implement.     

Prenatal histomorphological development of the reticulum in fallow deer (Dama dama)

The histomorphological changes occurring in the Dama dama reticulum during prenatal development have been investigated. Twenty‐five Dama dama embryos were used, from the first stages of prenatal life until birth. Differentiation of the reticulum was observed at 23% gestation. By 25% gestation the reticular wall comprised three layers: an internal epithelial layer, a middle layer of pluripotential blastemic tissue and an external layer or serosa. Primary reticular crests were visible at 38% gestation. Secondary reticular crests were observed at 61% gestation. Neuroendocrine cells were detected by synaptophysin (SYP) at 35% gestation, in the lamina propria‐submucosa, tunica muscularis, and serosa. Epithelial Cytokeratin‐18 (CK‐18) cells were observed at 35% gestation extended throughout the epithelial layers. The glial cells (vimentin –VIM‐ and glial fibrillary acidic protein‐GFAP‐markers) were discerned at 25% and 43% gestation, respectively, in myenteric and submucosal plexuses, lamina propria, muscularis mucosae, tunica muscularis, and perivascular connective tissue. The neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) markers were immunodetected at 75% and 80 gestation, respectively, in the lamina propria‐submucosa, muscularis mucosae, tunica muscularis, serosa, and myenteric plexuses. The prenatal development of the fallow deer reticular mucosa evidenced a considerable precocity similar to that previously reported in goat and red deer.     

Effect of the Heavy Metals Cu,Ni, Cd and Zn on the Growth and Reproduction of Epigeic Earthworms (E. fetida) during the Vermistabilization of Municipal Sewage Sludge

In order to enhance the removal of heavy metals such as Ni, Cu, Zn and Cd from wastewater, different cow dung/sewage sludge ratios were tested to assess the effect of these metals on the adaptability of Eisenia fetida earthworms to the treatment process carried out in a typical plant located in Tamaulipas, Mexico. Two experimental water treatment setups were proposed. The first set of experiments was planned to determine the adequate sewage sludge/cow dung ratio(s), whereas the second arrangement was designed to evaluate the growth performance and fecundity of the earthworms under high heavy metal concentrations. To achieve the objectives, the experiments were conducted for 90 days under controlled environmental conditions. Maximum worm biomass and growth rates were attained in samples containing 25 wt.% of sewage sludge. Weight and mortality of worms were significantly affected by the high levels of heavy metals, making difficult the metal accumulation in the worm tissues.     

Incidence of and yield loss caused by maize rayado fino virus in maize cultivars in Ecuador

Three sowing date trials, each planted with one cultivar, were performed to measure the natural incidence of the Maize rayado fino virus (MRFV). The lowest incidences (1–6%) were obtained at the sowing dates normally practised in the tested regions. Earlier or later sowing dates had higher to much higher incidences (up to 18 and 32%). Two cultivar trials, one with four cultivars and one with eight cultivars, showed significant differences in incidence, ranging from 14.0% in ‘Iniap-160’ to 2.0% in ‘Cadet-2’. In one trial with plots of 1000 m², the cultivar Iniap-122 was sown at three sowing dates. In each plot, plants that developed MRFV symptoms at the 8–10 leaf stage, at the 12–14 leaf stage and at the emergence of tassels were marked. Marked MRFV-affected plants were compared with non-MRFV-affected plants in their neighbourhood to estimate yield loss due to MRFV. The yield losses at the three sowing dates were 2.5, 1.6 and 4.8%, respectively. It was concluded that the yield loss due to MRFV is quite small provided sowing is restricted to the normal sowing period.     

Reattachment of tooth fragment: an in vitro study

Canine tooth fracture is common in dogs. Application of an esthetic and durable restoration may be challenging in veterinary dental practice. This study used traditional human dental laboratory methods to evaluate fracture strength of intact dog canine teeth and fractured teeth that had been restored by reattachment of the tooth fragment. The results showed that the teeth restored by reattachment of the tooth fragment supported a test load equal to 45.4 % of the load necessary to fracture intact canine teeth.     

Phenolics,Sugars, Antimicrobial and Free-Radical-Scavenging Activities of <Emphasis Type="Italic">Melicoccus bijugatus</Emphasis> Jacq. Fruits from the Dominican Republic and Florida

Edible fruits of the native South American tree Melicoccus bijugatus Jacq. are consumed fresh or in traditional food, drink and medicinal preparations. Some therapeutic effects of these fruits may be due to phenolics and sugars. Aqueous acetone, methanol or ethanol tissue extracts of different cultivars or collections of M. bijugatus fruits from the Dominican Republic and Florida were analyzed for total phenolics and free radical scavenging activity by UV-vis spectroscopy, sugars by gas chromatography, and antimicrobial activity by the disc diffusion assay. Total phenolics and free radical scavenging activities ranked: seed coat > embryo > pulp extracts. Montgomery cultivar fruits had the highest total phenolics. For sugars: pulp > embryo and highest in Punta Cana fruit pulp. In all extracts: sucrose > glucose and fructose. Glucose:fructose ratios were 1:1 (pulp) and 0.2:1 (embryo). Pulp extracts had dose-response antibacterial activity and pulp and embryo extracts had antifungal activity against one yeast species. Phenolics and sugars were confirmed with thin-layer chromatography and nuclear magnetic resonance. Sugar-free pulp fractions containing phenolics had slightly more antimicrobial activity than H₂O-soluble pulp fractions with sugars. Results indicate M. bijugatus fruits contain phenolics, sugars and other H₂O-soluble compounds consistent with therapeutic uses. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Plant‐associated invertebrates and ecological quality in some Mediterranean shallow lakes: implications for the application of the EC Water Framework Directive

• 1. The EC Water Framework Directive requires that Member States assess the ecological quality of their water bodies on the basis of a wide set of variables, including benthic invertebrates.
• 2. The aim of the study was to find one or more faunistic indices that could be related to ecological status of shallow lakes, independent of different macrophyte types.
• 3. Six invertebrate indices were calculated from abundance and biomass data in 10 Spanish shallow lakes: total abundance and biomass, Shannon's index, percentage of predators, percentage of Ephemeroptera, Plecoptera and Trichoptera, Orthocladiinae as a percentage of the total Chironomidae, and Chironominae as a percentage of the whole macroinvertebrate community. Taxon richness was also calculated.
• 4. Differences in the values of indices across different macrophyte types were explored by means of a one‐way analysis of variance. Significant differences were occasionally found when indices were calculated from biomass data. Total abundance was also significantly different across some architecture types.
• 5. No significant correlations were found between the overall values of the indices for each lake and the environmental variables measured (ecological status, total nitrogen, total phosphorus, chlorophyll a concentrations, dynamics of the water flow, and naturalness of the shore), except in the case of total biomass.
• 6. Values of indices were plotted (box plots) to detect potential differences between lakes of different ecological status. None of the index values was clearly related to ecological status. Thus, the approach used here, requiring relatively little sampling effort and taxonomic expertise, was of little use as a quality indicator for shallow lakes. The implementation of the Directive will therefore require different approaches to be developed and tested.

Copyright © 2004 John Wiley & Sons, Ltd.