Recovering Plant Microfossils from Archaeological and other Palaeoenvironmental Deposits: A Practical Guide Developed from Pacific Region Experience

Presented are revised procedures for recovering pollen and spores, phytoliths, and starch and other plant material from archaeological and other palaeoenvironmental deposits for microscopic analysis. The procedures are based on lengthy experience of preparing numerous samples of deposits from Malesia, Melanesia, Micronesia, and Polynesia. The procedures are designed as a simple laboratory guide, outlined in detail and summarized to provide a practical, time-efficient, step-by-step method. The method has been carried out successfully on many types of soils and other deposits from Pacific Islands, including: clays, silts, and sands; waterlogged, porous, peaty, volcanic, and coralline soils; and sediment cores, tools, pot sherds, dental calculus, and coprolites from a range of environmental settings in tropical, sub-tropical, and temperate climates. Also included in the procedures are mounting recovered microfossils on microscope slides and preparing and mounting modern reference samples

Introduced Dioscorea spp. starch in Lapita and later deposits, Vao Island, Vanuatu

Analysis of deposits at a Lapita site in Vanuatu revealed putative starch grains of Dioscorea nummularia in ∼2800-3100 cal. BP layers and of Dioscorea pentaphylla in a ∼2000 cal. BP layer, suggesting local cultivation of these tuberous crops. The Dio

Stream Reasoning in Temporal Datalog

In recent years, there has been an increasing interest in extending traditional stream processing engines with logical, rule-based, reasoning capabilities. This poses significant theoretical and practical challenges since rules can derive new information and propagate it both towards past and future time points; as a result, streamed query answers can depend on data that has not yet been received, as well as on data that arrived far in the past. Stream reasoning algorithms, however, must be able to stream out query answers as soon as possible, and can only keep a limited number of previous input facts in memory. In this paper, we propose novel reasoning problems to deal with these challenges, and study their computational properties on Datalog extended with a temporal sort and the successor function (a core rule-based language for stream reasoning applications)

Stratified Negation in Limit Datalog Programs

There has recently been an increasing interest in declarative data analysis, where analytic tasks are specified using a logical language, and their implementation and optimisation are delegated to a general-purpose query engine. Existing declarative languages for data analysis can be formalised as variants of logic programming equipped with arithmetic function symbols and/or aggregation, and are typically undecidable. In prior work, the language of $\mathit{limit\ programs}$ was proposed, which is sufficiently powerful to capture many analysis tasks and has decidable entailment problem. Rules in this language, however, do not allow for negation. In this paper, we study an extension of limit programs with stratified negation-as-failure. We show that the additional expressive power makes reasoning computationally more demanding, and provide tight data complexity bounds. We also identify a fragment with tractable data complexity and sufficient expressivity to capture many relevant tasks.Comment: 14 pages; full version of a paper accepted at IJCAI-1

Foundations of Declarative Data Analysis Using Limit Datalog Programs

Motivated by applications in declarative data analysis, we study $\mathit{Datalog}_{\mathbb{Z}}$---an extension of positive Datalog with arithmetic functions over integers. This language is known to be undecidable, so we propose two fragments. In $\mathit{limit}~\mathit{Datalog}_{\mathbb{Z}}$ predicates are axiomatised to keep minimal/maximal numeric values, allowing us to show that fact entailment is coNExpTime-complete in combined, and coNP-complete in data complexity. Moreover, an additional $\mathit{stability}$ requirement causes the complexity to drop to ExpTime and PTime, respectively. Finally, we show that stable $\mathit{Datalog}_{\mathbb{Z}}$ can express many useful data analysis tasks, and so our results provide a sound foundation for the development of advanced information systems.Comment: 23 pages; full version of a paper accepted at IJCAI-17; v2 fixes some typos and improves the acknowledgment

The Bag Semantics of Ontology-Based Data Access

Ontology-based data access (OBDA) is a popular approach for integrating and querying multiple data sources by means of a shared ontology. The ontology is linked to the sources using mappings, which assign views over the data to ontology predicates. Motivated by the need for OBDA systems supporting database-style aggregate queries, we propose a bag semantics for OBDA, where duplicate tuples in the views defined by the mappings are retained, as is the case in standard databases. We show that bag semantics makes conjunctive query answering in OBDA coNP-hard in data complexity. To regain tractability, we consider a rather general class of queries and show its rewritability to a generalisation of the relational calculus to bags

Traditional Land Use and Resistance to Spanish Colonial Entanglement: Archaeological Evidence on Guam

Documenting the continuity of traditional land use practices on Guam, from before Spanish Contact in 1521 to after the Colonial La Reducción ca. 1700, is provocative. La Reducción refers to a period after Spanish settlement in 1668 when all indigenous inhabitants of northern Guam were removed from their traditional homes and sent to six southern villages under the watchful eye of administrative and religious authorities, except those residing on the island of Rota. Recent geoarchaeological excavations at Site 66-08-0141, located on the northern plateau in South Finegayan, have exposed at least two latte sets or pre-Contact habitations with traditional Micronesian earth ovens postdating Spanish settlement. Artifacts included Latte Period pottery, marine shell adzes, a limestone sling stone, and historic to modern refuse from WWII to the modern era. Microfossil evidence of pandanus, coconuts, and likely cultivation of rice and taro have expanded our understanding of subsistence farming in micro-environments within the tropical forest a generation or more after 1700 and La Reducción. This suggests that archaeological evidence of land use continuity and indigenous resistance and accommodation to Spanish Colonial entanglement exists, while challenging prior historiography across the Pacific; such sites hold much potential to bring native voices to early communities long disenfranchised by the colonization experience

Ages on weathered Plio-Pleistocene tephra sequences, western North Island, New Zealand

Using the zircon fission-track method, we have obtained five ages on members of two strongly-weathered silicic, Pliocene-Pleistocene tephra sequences, the Kauroa and Hamilton Ash formations, in western North Island, New Zealand. These are the first numerical ages to be obtained directly on these deposits. Of the Kauroa Ash sequence, member K1 (basal unit) was dated at 2.24 ± 0.29 Ma, confirming a previous age of c. 2.25 Ma obtained (via tephrochronology)from K/Ar ages on associated basalt lava. Members K2 and K3 gave indistinguishable ages between 1.68 ± 0.12 and 1.43 ± 0.17 Ma. Member K12, a correlative of Oparau Tephra and probably also Ongatiti Ignimbrite, was dated at 1.28 ± 0.11 Ma, consistent with an age of 1.23 ± 0.02 Ma obtained by various methods on Ongatiti Ignimbrite. Palaeomagnetic measurements indicated that members K13 to K15 (top unit, Waiterimu Ash) are aged between c. 1.2 Ma and 0.78 Ma. Possible sources of the Kauroa Ash Formation include younger volcanic centres in the southern Coromandel Volcanic Zone or older volcanic centres in the Taupo Volcanic Zone, or both. Of the Hamilton Ash sequence, the basal member Ohinewai Ash (HI) was dated at 0.38 ± 0.04 Ma. This age matches those obtained by various methods on Rangitawa Tephra of 0.34-0.35 Ma, supporting correlation with this Whakamaru-caldera derived deposit. The origin of the other Hamilton Ash beds is unknown but various younger volcanic centres in the Taupo Volcanic Zone are possible sources. The topmost member, Tikotiko Ash (H6-H7), is estimated to be aged between c. 0.18 and 0.08 Ma. Various silicic pyroclastic deposits documented in North Island and in marine cores may be co-eval with members of the Kauroa Ash and Hamilton Ash sequences on the basis of their age

The Window Validity Problem in Rule-Based Stream Reasoning

Rule-based temporal query languages provide the expressive power and flexibility required to capture in a natural way complex analysis tasks over streaming data. Stream processing applications, however, typically require near real-time response using limited resources. In particular, it becomes essential that the underpinning query language has favourable computational properties and that stream processing algorithms are able to keep only a small number of previously received facts in memory at any point in time without sacrificing correctness. In this paper, we propose a recursive fragment of temporal Datalog with tractable data complexity and study the properties of a generic stream reasoning algorithm for this fragment. We focus on the window validity problem as a way to minimise the number of time points for which the stream reasoning algorithm needs to keep data in memory at any point in time