Multilayer Networks

In most natural and engineered systems, a set of entities interact with each other in complicated patterns that can encompass multiple types of relationships, change in time, and include other types of complications. Such systems include multiple subsystems and layers of connectivity, and it is important to take such "multilayer" features into account to try to improve our understanding of complex systems. Consequently, it is necessary to generalize "traditional" network theory by developing (and validating) a framework and associated tools to study multilayer systems in a comprehensive fashion. The origins of such efforts date back several decades and arose in multiple disciplines, and now the study of multilayer networks has become one of the most important directions in network science. In this paper, we discuss the history of multilayer networks (and related concepts) and review the exploding body of work on such networks. To unify the disparate terminology in the large body of recent work, we discuss a general framework for multilayer networks, construct a dictionary of terminology to relate the numerous existing concepts to each other, and provide a thorough discussion that compares, contrasts, and translates between related notions such as multilayer networks, multiplex networks, interdependent networks, networks of networks, and many others. We also survey and discuss existing data sets that can be represented as multilayer networks. We review attempts to generalize single-layer-network diagnostics to multilayer networks. We also discuss the rapidly expanding research on multilayer-network models and notions like community structure, connected components, tensor decompositions, and various types of dynamical processes on multilayer networks. We conclude with a summary and an outlook.Comment: Working paper; 59 pages, 8 figure

Towards a Middle Pleistocene terrestrial climate reconstruction based on herpetofaunal assemblages from the Iberian Peninsula : state of the art and perspectives

This paper has been mainly funded by the University of Reading and also by projects CGL2016-80000-P (Spanish Ministry of Economy and Competitiveness) and 2017SGR-859 (Generalitat de Catalunya).The pattern of the varying climatic conditions in southern Europe over the last million years is well known from isotope studies on deep-ocean sediment cores and the long pollen records that have been produced for lacustrine and marine sedimentary sequences from Greece, Italy and the Iberian margin. However, although relative glacial and interglacial intensities are well studied, there are still few proxies that permit quantitative terrestrial temperature and precipitation reconstruction. In this context, fauna-based climate reconstructions based on evidence preserved in archaeological or palaeontological sites are of great interest, even if they only document short windows of that climate variability, because (a) they provide a range of temperature and precipitation estimates that are understandable in comparison with present climate; (b) they may allow the testing of predicted temperature changes under scenarios of future climate change; and (c) quantitative temperature and precipitation estimates for past glacials and interglacials for specific regions/latitudes can help to understand their effects on flora, fauna and hominids, as they are directly associated with those cultural and/or biological events. Moreover such reconstructions can bring further arguments to the discussion about important climatic events like the Mid-Bruhnes Event, a climatic transition between moderate warmths and greater warmths during interglacials. In this paper we review a decade of amphibian- and reptile-based climate reconstructions carried out for the Iberian Peninsula using the Mutual Ecogeographic Range method in order to present a regional synthesis from MIS 22 to MIS 6, discuss the climate pattern in relation to the Mid-Bruhnes Event and the thermal amplitude suggested by these estimates and finally to identify the chronological gaps that have still to be investigated.PostprintPeer reviewe

Palynological investigations in the Orce Archaeological Zone, Early Pleistocene of Southern Spain

Palynological investigations in the Orce Archaeological Zone (OAZ) (Guadix-Baza Basin, Granada, Spain), Venta Micena 1 (VM1), Barranco Leon (BL) and Fuente Nueva 3 (FN3) are presented. This archaeological region is con-nected with the first Homo populations in Western Eurasia during the Early Pleistocene. The VM1 pollen record is characterized by Ephedra, and to a lesser extent, Pinus, Juniperus and evergreen Quercus, occassionally accompa-nied by Olea, Genisteae, Erica, deciduous Quercus, Alnus, Castanea, Fraxinus, Salix and Phillyrea. BL is dominated by Juniperus, Olea, Pinus, Poaceae, and evergreen Quercus. FN3 is characterized by an open Mediterranean woodland dominated by evergreen Quercus, Pinus, Juniperus and Olea, accompanied by deciduous Quercus, Castanea, Populus, Salix, Ulmus, Fraxinus, Pistacia, Phillyrea, Genisteae, Erica, Cistus, and Ephedra fragilis. Relic Tertiary taxa in OAZ include Carya, Pterocarya, Eucommia, Zelkova, and Juglans. The Early Pleistocene OAZ vegetation is a mosaic of different landscapes embracing mesophytes, thermophytes, xerophytes, xerothermophytes, and Mediterra-nean elements. These finds are compared with former pollen analyses in the region and beyond within the Ibe-rian Peninsula. (c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).Peer reviewe

New stratigraphically constrained palaeoenvironmental reconstructions for the first human settlement in Western Europe : The Early Pleistocene herpetofaunal assemblages from Barranco Leon and Fuente Nueva 3 (Granada, SE Spain)

The Early Pleistocene sites of Barranco Leon and Fuente Nueva 3 (Guadix-Baza Basin, SE Spain) have yielded abundant Oldowan lithic artifacts and one hominin tooth (Homo sp. in level D1 or D2 of Barranco Leon), today considered to be among the earliest evidence for a hominin presence in Western Europe, at ca. 1.4-1.2 Ma. Here, for the first time, the stratigraphic succession of these two sites are studied more precisely from a palaeoenvironmental point of view, taking into account the different levels of the depositional sequences to analyze the successive fossil assemblages of amphibians and reptiles. Palaeoenvironmental reconstructions are carried out by applying the "habitat weighting" method, which uses the modern distribution by habitat of amphibian and reptile species in order to interpret past landscapes. The successive herpetofaunal assemblages from Barranco Leon show a certain tendency towards more arid conditions from level D1 to level E, whereas in Fuente Nueva 3 environmental reconstructions reveal oscillating conditions, with a tendency towards more arid conditions in the basal part of the sequence, up to level 5, where the tendency shifts back to more humid conditions. Our results show that the layers included in this study with the highest density of anthropic evidence (such as level 5 in FN 3 and levels D1 and D2 in BL) are situated within the late Early Pleistocene climatic and environmental cyclicity, yielding different environmental conditions: a humid, wooded biotope for BL, and a more open and drier biotope in FN 3. This suggests that the hominins of the late Early Pleistocene, although conditioned to some extent by climatic factors, were able to cope with changing environmental conditions, both "interglacial" and "glacial", in the southwestern extremity of the European continent. (C) 2020 Elsevier Ltd. All rights reserved.Peer reviewe

Taphonomic and spatial analyses from the Early Pleistocene site of Venta Micena 4 (Orce, Guadix-Baza Basin, southern Spain)

Venta Micena is an area containing several palaeontological sites marking the beginning of the Calabrian stage (Early Pleistocene). The richness of the fossil accumulation including species of Asian, African and European origin, makes Venta Micena a key site for the the palaeoecological and palaeoenvironmental study of southern Europe during the Early Pleistocene. Thus, research has been focused on Venta Micena 3, which was originally interpreted as a single palaeosurface associated with a marshy context, in which most of the fauna was accumulated by Pachycrocuta brevirostris. Recent excavations have unearthed a new site, Venta Micena 4, located in the same stratigraphic unit (Unit C) and in close proximity to Venta Micena 3. Here we show the first analyses regarding the taphonomic and spatial nature of this new site, defining two stratigraphic boundaries corresponding to two different depositional events. Furthermore, the taphonomic analyses of fossil remains seem to indicate a different accumulative agent than Pachycrocuta, thus adding more complexity to the palaeobiological interpretation of the Venta Micena area. These results contribute to the discussion of traditional interpretations made from Venta Micena 3.Peer reviewe

To den or not to den. Contributions to the taphonomic history of the Early Pleistocene site of Venta Micena 4 (Orce, Guadix-Baza Basin)

Venta Micena (Orce, Guadix-Baza Basin, Spain) is an Early Pleistocene locality renowned for the richness and quality of its palaeontological record. VM is spread over an area of 2.5 km2, where several exposed fossil outcrops are visible amidst its gorges and ravines. The best known of these sites, VM3, has been interpreted as a hyaena den. In addition, a new site, named VM4, has recently been the focus of fieldwork and taphonomic studies. The publication by Luzón et al. (2021) pointed out that VM4 presents a more complex history than VM3. First, two different sub-levels were identified: VM4-I and VM4-II. Secondly, the preliminary taphonomic analysis showed conspicuous differences with regard to VM3. Nevertheless, such interpretation has been challenged by Palmqvist et al. (2022) who proposed that VM3 and VM4 are both the result of a single depositional process, entailing the selective transport of skeletal parts by the giant extinct hyaena Pachycrocuta brevirostris back to its den. Using well-preserved faunal elements whose depositional context and provenance are reliable, in this paper we show that: 1) there are two clearly defined sub-levels in VM4 with some shared taphonomic characteristics as well as some notable differences; 2) VM3 and VM4 exhibit enough divergence to support differences in site formation processes; 3) The interpretation of both VM4-I and VM4-II is more consistent with their characterisation as open-air sites in which multiple agents and depositional processes contributed to its formation, rather than with hyaena dens. Nevertheless, excavations are still in progress at VM4 and therefore any results and interpretations ought to be considered as provisional

Use of meat resources in the Early Pleistocene assemblages from Fuente Nueva 3 (Orce, Granada, Spain) (vol 13, 213, 2021)

Correction to: Archaeological and Anthropological Sciences (2021) 13: 213Peer reviewe

Unravelling Hominin Activities in the Zooarchaeological Assemblage of Barranco Leon (Orce, Granada, Spain)

Little is known about the subsistence practices of the first European settlers, mainly due to the shortage of archaeological sites in Europe older than a million years. This article contributes to the knowledge of the subsistence of the first Europeans with new zooarchaeology and taphonomic data from the Palaeolithic site of Barranco Leon (Orce, Granada, Spain). We present the results of the analysis of the faunal assemblages retrieved in the context of new excavations undertaken between 2016 and 2020. We have followed a standard methodology for the identification and quantification of species, mortality profiles, skeletal representation and taphonomic analysis. With regard to the taphonomic evidence, we have documented the extent of rounding, abrasion and other alterations. Finally, we examined traces from the activities of carnivores and hominins that led to the accumulation and alteration of the bone assemblages. Results indicate that the archaeo-paleontological deposits from Barranco Leon present a dual-patterned mixed taphonomic origin. The first phase primarily involved waterborne processes (BL-D1), which led to the accumulation of lithic raw materials, a few archaeological stone tools, and some faunal remains with percussion and cutmarks. The second phase (BL-D2) contains several stone tools associated with faunal remains with more anthropogenic alterations, such as cutmarks and percussion marks. After analysing the Barranco Leon zooarchaeological assemblage, the present study concludes that hominins had access to the meat and within-bone nutrients of animals of diverse sizes. However, the specific carcass acquisition mechanisms that hominins followed are less certain because the presence of tooth marks suggests that carnivores also played a role in the accumulation and modification of the Barranco Leon faunal assemblage.Peer reviewe

Pliocene to Middle Pleistocene climate history in the Guadix-Baza Basin, and the environmental conditions of early Homo dispersal in Europe

The Guadix-Baza Basin (GBB) in Andalucia, Spain, comprises palaeontological and archaeological sites dating from the Early Pliocene to the Middle Pleistocene, including some of the earliest sites with evidence for the presence of early humans (Homo sp.) in Europe. Thus, the history of climate and environments in this basin contributes significantly to our understanding of the conditions under which early humans spread into Europe during the Early Pleistocene. Here we present estimates of precipitation and primary productivity in the GBB from the Pliocene to the Middle Pleistocene based on dental ecometrics in fossil communities of large herbivorous mammals, and perform an ecometrics-based distribution modelling to analyse the environmental conditions of Early and Middle Pleistocene human sites in Europe. Our results show that Early Pleistocene humans generally occupied on average relatively diverse habitats with ecotones, such as woodlands and savannas, but avoided very open and harsh (cool or dry) environments. During the Middle Pleistocene in Europe, humans occupied a comparatively much broader range of environments than during the Early Pleistocene, but were on average more concentrated in environments where the dental ecometric of mammals indicate wooded palaeoenvironments. In the earliest human occupation sites of the GBB, Barranco Leon and Fuente Nueva 3, the mean annual precipitation and net primary production estimates indicate climatic conditions close to modern Mediterranean sclerophyllous woodland environments, but with slightly higher primary productivity, indicating some similarity with East African woodlands. On the other hand, the environments did not resemble African grassland savannas. The browse-dominated diets of ungulates from Barranco Leon and Fuente Nueva 3 further suggest palaeoenvironments where grasses were a minor component of the vegetation. In the slightly older site of Venta Micena that has no evidence for the presence of hominins, dental ecometric estimates indicate climate and environments similar to Mediterranean "forest steppe" environments existing in the surroundings of Baza today. Grasses were prevalent in the diet of some taxa, especially equids, in Venta Micena, but most of the species show browse-dominated diets even there. (C) 2021 The Authors. Published by Elsevier Ltd.Peer reviewe

Rice Management Decisions Using Process-Based Models With Climate-Smart Indicators

Irrigation strategies are keys to fostering sustainable and climate-resilient rice production by increasing efficiency, building resilience and reducing Greenhouse Gas (GHG) emissions. These strategies are aligned with the Climate-Smart Agriculture (CSA) principles, which aim to maximize productivity whilst adapting to and mitigating climate change. Achieve such mitigation, adaptation, and productivity goals- to the extent possible- is described as climate smartness. Measuring climate smartness is challenging, with recent progress focusing on the use of agronomic indicators in a limited range of contexts. One way to broaden the ability to measure climate-smartness is to use modeling tools, expanding the scope of climate smartness assessments. Accordingly, and as a proof-of-concept, this study uses modeling tools with CSA indicators (i.e., Greenhouse Intensity and Water Productivity) to quantify the climate-smartness of irrigation management in rice and to assess sensitivity to climate. We focus on a field experiment that assessed four irrigation strategies in tropical conditions, Continuous Flooding (CF), Intermittent Irrigation (II), Intermittent Irrigation until Flowering (IIF), and Continuous soil saturation (CSS). The DNDC model was used to simulate rice yields, GHG emissions and water inputs. We used model outputs to calculate a previously developed Climate-Smartness Index (CSI) based on water productivity and greenhouse gas intensity, which score on a scale between−1 (lack of climate-smartness) to 1 (high climate smartness) the climate-smartness of irrigation strategies. The CSS exhibited the highest simulation-based CSI, and CF showed the lowest. A sensitivity analysis served to explore the impacts of climate on CSI. While higher temperatures reduced CSI, rainfall mostly showed no signal. The climate smartness decreasing in warmer temperatures was associated with increased GHG emissions and, to some extent, a reduction in Water Productivity (WP). Overall, CSI varied with the climate-management interaction, demonstrating that climate variability can influence the performance of CSA practices. We conclude that combining models with climate-smart indicators can broaden the CSA-based evidence and provide reproducible research findings. The methodological approach used in this study can be useful to fill gaps in observational evidence of climate-smartness and project the impact of future climates in regions where calibrated crop models perform well