A modular approach to Integrated Assessment modeling

In this paper, we present a new approach to model coupling that probably forms the methodological basis of a new generation of Integrated Assessment models. This approach respects the knowledge and expertise that is embodied in existing models and encourages their gradual evolution. Modularity is the guiding principle. Our approach is distinguished by the way modules are coupled which is based on an interplay of a job control module, a numerical coupling module, and a couple of stand-alone functional modules. The numerical coupling module - the core component - serves to treat the feedbacks between the functional modules. A first implemented example that couples an economic and a climate module by means of a two-phase meta-optimization is presented here. The algorithm and mathematical structure behind are discussed as well as important features such as convergence behavior and reliability.     

First Castorid (Mammalia,Rodentia) from the Middle Miocene of Southeast Asia

Today and in the Tertiary, the geographical distribution of castorids is limited throughout all of the northern continents. Fossils of the Castoridae genus Steneofiber are abundant in many localities of Eurasia from the late Oligocene to Pliocene period. Recently, Steneofiber fossils were discovered in two localities of northern Thailand, Mae Moh and Chiang Muan coal mines, in layers of late middle Miocene age. These discoveries represent the first records of castorids from Southeast Asia and correspond to their southernmost known range. The focus of this study is to describe this new Thai species of Steneofiber and to define its wear stages from the molar occlusal surfaces by using micro-CT scan analysis. The CT scan technique permits the analysis of the virtual occlusal surface changes from wear, allowing easier comparison to related species of Steneofiber cheek teeth without destroying the teeth. The new species, Steneofiber siamensis n. sp., can be distinguished from the other species of Steneofiber by several distinct characters, longer mesostriid on p4, presence of premesostria and metastria on P4, which are smaller than most of the other known species. The occurrence of this new castorid also supports a subtropical to tropical paleoclimate for these two localities of northern Thailand.     

Stable carbon isotope reconstructions of diet and paleoenvironment from the late Middle Pleistocene Snake Cave in Northeastern Thailand

Thailand’s geographical location in the tropics and almost complete, relatively uninterrupted forest cover makes it valuable for paleodiet and paleoclimate research. We present the first dietary and environmental reconstructions in Northeastern Thailand, using stable isotope abundances in mammalian tooth enamel from the late Middle Pleistocene locality, Tham Wiman Nakin (Snake Cave), which reflect a much higher (over 70%) than modern (13%) occurrence of C4 plants. Bovids and cervids appear to have had almost entirely a C4 plant diet. Carnivores consumed a mixture of C3 (suids) and C4 (bovids, cervids) consumers. Rhinoceroses and orangutan appear to have maintained their preference through time for forested or open C3 environment, respectively. ¹³C/¹²C from bone bioapatite, horn and hair of modern Southeast Asian mammals almost exclusively demonstrate C3 vegetation dominance. C4 consumption is rare in analysed modern species and it could be related to anthropogenic influences such as ingestion of domestic crops or livestock. Interesting implications emerge in the C4 vegetation distribution in southern Eurasian ecosystems, indicating that Southeast Asia, south of the Tibet, could be part of the global C4 vegetation spread, which occurred around 7 Ma. However, the C4 percentage in ecosystems varied geographically. Despite modern reversal towards C3 habitats due to factors such as increasing CO₂, we think that anthropological influences may be responsible for habitat and dietary changes in extant species. Bovids demonstrate the most significant shift in diet and habitat through time, from C4-dominated open habitats to C3-dominated habitats indicative of dense forest understory.     

Dietary characterization of the hominoid Khoratpithecus (Miocene of Thailand): evidence from dental topographic and microwear texture analyses

The genus Khoratpithecus, a hominoid thought to be related to the orangutan lineage, is represented by two known fossil species K. chiangmuanensis and K. piriyai. Both were discovered in Southeast Asia (Thailand) and are dated to the Middle and Late Miocene, respectively. In this study, dental topographic and microwear texture analyses were used to examine molars from both of these species, with the goal of understanding their dietary preferences. Although sample sizes are small for Khoratpithecus, available data are compared to that collected for extant apes. Environmental evidence, such as botanical remains and sedimentological data, is also considered for comparisons with dietary reconstruction. Results from dental topographic analysis suggest that the two fossil species were better adapted to a diet of fruits than to one of leaves, much like the living orangutan or chimpanzee. Results from microwear texture analysis further support this, suggesting that Khoratpithecus preferred soft fruits to hard fruits or seeds. And finally, the botanical and sedimentological evidence point to environments for Khoratpithecus that would have been compatible with a fruit-eating species. Given the small sample sizes available for analysis, however, definitive judgments are not yet possible at this time.     

Multimodal signals,imperfect information,and identification of sex in red-backed salamanders (<Emphasis Type="Italic">Plethodon cinereus</Emphasis>)

Theoretical treatments and empirical studies both suggest that signals that occur in multiple sensory modes have superior detectabilities, discriminabilities, and memorabilities. There is also an intuitive link between signal detectability, discriminability, and memorability and the quality of information that is transferred via the signaler. We investigated the role of information quality and sensory modality in the sexual identification of intruding conspecifics by territorial male red-backed salamanders (Plethodon cinereus). Our results imply that these salamanders are able to discriminate between intruding male and female conspecifics (based on the allocation of aggression) in bimodal scenarios (vision and olfaction) even under situations in which the information available about the intruders sexual identities is reduced in quality. In unimodal scenarios (olfaction only), male residents exhibited heightened levels of aggression toward male secretions and reduced levels of aggression toward female secretions. In unimodal scenarios where information pertaining to the sex of the stimulus was reduced in quality, male residents displayed intermediate levels of aggression relative to the responses that male and female stimuli received respectively. Although resident males touched bimodal stimuli significantly more than they touched unimodal stimuli, we were unable to find support for the notion that sensory modality greatly influences how male resident red-backed salamanders allocate aggression toward intruding male versus female stimuli.Communicated by H. Kokko     

Invasive species impacts on ecosystem structure and function: A comparison of Oneida Lake, New York, USA, before and after zebra mussel invasion

Exotic species invasion is widely considered to affect ecosystem structure and function. Yet, few contemporary approaches can assess the effects of exotic species invasion at such an inclusive level. Our research presents one of the first attempts to examine the effects of an exotic species at the ecosystem level in a quantifiable manner. We used ecological network analysis (ENA) and a social network analysis (SNA) method called cohesion analysis to examine the effect of zebra mussel (Dreissena polymorpha) invasion on the Oneida Lake, New York, USA, food web. We used ENA to quantify ecosystem function through an analysis of food web carbon transfer that explicitly incorporated flow over all food web paths (direct and indirect). The cohesion analysis assessed ecosystem structure through an organization of food web members into subgroups of strongly interacting predators and prey. Our analysis detected effects of zebra mussel invasion throughout the entire Oneida Lake food web, including changes in trophic flow efficiency (i.e., carbon flow among trophic levels) and alterations of food web organization (i.e., paths of carbon flow) and ecosystem activity (i.e., total carbon flow). ENA indicated that zebra mussels altered food web function by shunting carbon from pelagic to benthic pathways, increasing dissipative flow loss, and decreasing ecosystem activity. SNA revealed the strength of zebra mussel perturbation as evidenced by a reorganization of food web subgroup structure, with a decrease in importance of pelagic pathways, a concomitant rise of benthic pathways, and a reorganization of interactions between top predator fish. Together, these analyses allowed for a holistic understanding of the effects of zebra mussel invasion on the Oneida Lake food web.     

Evaluating the efficiency of municipalities in collecting and processing municipal solid waste: A shared input DEA-model

This paper proposed an adjusted "shared-input" version of the popular efficiency measurement technique Data Envelopment Analysis (DEA) that enables evaluating municipality waste collection and processing performances in settings in which one input (waste costs) is shared among treatment efforts of multiple municipal solid waste fractions. The main advantage of this version of DEA is that it not only provides an estimate of the municipalities overall cost efficiency but also estimates of the municipalities' cost efficiency in the treatment of the different fractions of municipal solid waste (MSW). To illustrate the practical usefulness of the shared input DEA-model, we apply the model to data on 293 municipalities in Flanders, Belgium, for the year 2008.