Detecting travelling ionospheric disturbances in incoherent scatter data using the maximum entropy method

Two different methods of determining autoregressive coefficients in Maximum Entropy Method (MEM) were compared, investigating power spectra of synthetic signals consisting of three sinusoids and white noise of relatively high level. Spectral line shifts due to the initial phases changes were evaluated. Burg's method was chosen for determining power spectra of experimental signals. Simulating the incoherent scatter data obtained with EISCAT, it was shown that the increasing noise and wave attenuation effects are difficult to separate. Integrating the ME spectral density it was found that, in many cases, it is impossible to reproduce the true power of each harmonic of the signal.     

A comparison of ionization densities determined from spacecraft and incoherent scatter radar data

By comparing direct measurements taken from onboard Atmosphere Explorer spacecraft (AE), in eccentric orbit, with incoherent scatter radar (ISR) measurements taken from the ground, we illustrate both the merits and the difficulties involved in such comparisons. Five altitude profiles of ionization determined from AE, in near coincidence with ground stations making ISR measurements, compared favorably with the ISR data so long as the AE measurements were properly analyzed for the effects of variations in latitude and solar zenith angle along the spacecraft orbit.     

Studies of the cusp and auroral zone with incoherent scatter radar: the scientific and technical case for a polar-cap radar

A combined scientific and technical case is presented for the establishment of a new incoherent scatter radar facility on the archipelago of Svalbard. The scientific case rests principally on the ability of such a system to contribute significantly to the elucidation of the chain of physical processes involved in solar wind-magnetosphere-ionosphere-thermosphere coupling, particularly those processes associated with the dayside cusp and auroral zone. These latter regions map magnetically to the vicinity of the dayside magnetopause, and the consequent prospect of conducting co-ordinated observations with the ESA Cluster spacecraft at high altitudes provides strong motivation for ensuring that the radar facility becomes operational no later than 1995. Important features of the Svalbard site include its relatively high geographic latitude, which allows cusp aurorae to be observed under winter solstice conditions, and its proximity to the existing EISCAT incoherent scatter system, with the possibility of joint operations. The latter possibility is not only important for studies of the structure and motion of the high-latitude ionosphere, but is also particularly significant for plasma-physics investigations, which form another major topic of study. It is possible that the facility will be able to contribute significantly to polar stratospheric-tropospheric circulation studies relevant to the ozone-depletion problem. To accomplish these objectives, a tristatic radar system, capable of making full velocity vector measurements, would be ideal. However, the realization of such a system on the islands of Svalbard would present formidable logistic difficulties and an adequate alternative would be a system with three co-located fully steerable parabolic antennae, which could be operated either independently or together, in any combination. This configuration lends itself to a construction scheme that would allow significant observations to be made at an early stage with a partial radar system. The proposed construction scheme could be implemented by 1995 and would have sufficient flexibility to incorporate possible enhancements to the radar system in the future.     

Detection of chloride from pottery as a marker for salt: A new analytical method validated using simulated salt-making pottery and applied to Japanese ceramics

Salt is an essential mineral in the human diet, and ancient peoples obtained salt either directly from rock salt, from salt lakes, or by concentrating saline waters from salt springs or seawater in pottery vessels. However, because sodium chloride, the major component of salt, is soluble in water, it has been thought unlikely that any trace of salt would remain in the pottery after a long period of time. A new methodology for retrieval of water-insoluble (retainable) chloride ion trapped within a pottery matrix is presented as a method for detecting previous use of the pottery for salt making. Simulated salt-making pottery was used to make salt by repeatedly boiling seawater over a fire. After chloride had been extracted with distilled water, to mimic the removal of chloride by natural waters such as rainwater and groundwater, an aqueous ammonium fluoride solution was shown to be capable of extracting chloride ions remaining in the pottery. A chloride-selective electrode was used to quantify the amount of extracted chloride in the presence of fluoride. This method was then successfully applied to excavated Japanese pottery vessels suspected of having been used for making salt. Identification of retainable chloride in pottery can offer insights into salt trading networks, which reflect the growth and affluence of an ancient society.     

The estimation of body weight of the reindeer (Rangifer tarandus L.) from skeletal measurements: preliminary analyses and application to archaeological material from 17th- and 18th-century northern Finland

Abstract

In this study, a variety of postcranial skeletal measurements of reindeer (Rangifer tarandus L.) are used to predict the body mass. Regression equations for estimating the body weight of females as well as correction factors for estimating the weight of males are generated. These are applied to archaeological reindeer bones from 17th- and 18th-century Northern Finland. Predicted weights of archaeological reindeer correspond well with the weight of modern reindeer. Sexual dimorphism, however, caused problems in this analysis, since the criteria used for sex assessment affect the body weight prediction and thus the results of inter-assemblage comparisons.     

Dacura: A new solution to data harvesting and knowledge extraction for the historical sciences

New advances in computer science address problems historical scientists face in gathering and evaluating the now vast data sources available through the Internet. As an example we introduce Dacura, a dataset curation platform designed to assist historical researchers in harvesting, evaluating, and curating high-quality information sets from the Internet and other sources. Dacura uses semantic knowledge graph technology to represent data as complex, inter-related knowledge allowing rapid search and retrieval of highly specific data without the need of a lookup table. Dacura automates the generation of tools to help non-experts curate high quality knowledge bases over time and to integrate data from multiple sources into its curated knowledge model. Together these features allow rapid harvesting and automated evaluation of Internet resources. We provide an example of Dacura in practice as the software employed to populate and manage the Seshat databank.     

A volcanic inclusions based approach for provenance studies of archaeological ceramics: application to pottery from southern Italy

This work focuses on petro-chemical characterisation of the volcanic inclusions often found within the fabric of many ceramic remains from various archaeological sites in eastern Sicily. Petrographic observations and EMP analyses revealed that volcanic glass is strongly influenced by chemical modifications during the firing process, whereas clinopyroxenes keep their original composition unaltered thus constituting an effective tool for provenance attributions. Multivariate statistical analysis of the latter can in fact unambiguously discriminate between different productive areas by comparisons with pyroxenes from volcanics belonging to distinct magmatic provinces. The method proposed here was tested on ceramic remains of different ages and typologies found in southern Italy.     

Seismic refraction tomography surveys as a method for voids detection: an application to the archaeological park of Cava Ispica,Sicily, Italy

Geophysical surveys are commonly used in areas where the presence of ancient civilizations is historically documented. These investigations are able to detect through indirect methods the presence of bodies or structures in the subsoil measuring the variations of some physical parameters, obtaining information about archaeological remains without causing harm to them.

In the present study, we investigated the presence of anthropogenic buried cavities partially filled with rubble material, in an area located in the northern part of Cava Ispica, one of the most important archaeological sites located in south-eastern Sicily. The results of seismic refraction prospections, processed with tomographic methods, are presented and discussed. The entire valley contains prehistoric burial sites, Christian catacombs and residential units of various kinds. Despite the numerous searches made over past years, much still remains to be discovered.

The seismic refraction tomographic data, analyzed in 3D, revealed the presence of low velocity values (<400 m/s) areas that, considering the lithotypes locally present and the features of other archaeological structures discovered during previous surveys, can be ascribed to the presence of possible cavities. The obtained results show how such geophysical inspections represent an important preliminary tool for archaeological surveys.     

The ‘caries correction factor’: A new method of calibrating dental caries rates to compensate for antemortem loss of teeth

Dental caries rates are frequently based exclusively upon the number of carious teeth observed in a human skeletal series. However, a portion of the teeth lost antemortem will be lost because of severe carious decay, a factor not considered by many investigators. This paper reviews and critiques earlier attempts to adjust dental caries rates to account for antemortem loss of teeth, and proposes a new ‘caries correction factor’ that is population specific, requires no assumptions, and is sensitive to the temporal and ecogeographical context of a skeletal series. An example of how to apply this caries correction factor is provided using new data from the Bronze Age site of Harappa in northern Pakistan. Its value in dental palaeopathology is reviewed with two recent studies of dental caries in the Arabian Gulf, and concludes with a consideration of its possible application to non-human primates.