Hasil untuk "Prehistoric archaeology"

Francesca Matteucci

The time-delay model is the way we interpret the diagram [X/Fe] vs. [Fe/H], where X is the abundance of a generic element from carbon to uranium. This interpretation is based on the lifetimes of stars of different masses producing different elements. The abundance of Fe ([Fe/H]) traces the "stellar metallicity" and is due to supernovae Type Ia, which are believed to be the major producers of Fe, and in part to supernovae core-collapse. In particular, if X is an alpha-element, produced on short timescales from massive stars, the ratio [alpha/Fe] will show an overabundance of the alpha-elements relative to Fe at low metallicity. In fact, the bulk of Fe is produced with a time delay relative to alpha-elements, since Type Ia supernovae are white dwarfs in binary systems and they can have lifetimes as long as the age of the Universe. In this paper, I will show how powerful is the time-delay model in order to interpret the abundance patterns observed in stars and interstellar gas, since it allows us to put constraints on stellar nucleosynthesis as well as on the star formation histories of galaxies. I will present some applications of the time-delay model, in particular to the chemical evolution of the Milky Way and galaxies of different morphological type as well as to the identification of high redshift objects by means of their abundances.

Rositsa Manova, Stefan Alexandrov, Daniela Kovacheva et al.

This paper discusses the interdisciplinary analyses of an Early Bronze Age secondary barrow grave related to the Yamnaya culture in northeast Bulgaria. The analytical results produced firm evidence of ritual practices in Yamnaya communities aiming at the preservation of skeletons by coating them with CaCO3 and/or by additionally painting certain skeletal elements with hematite. This practice could have been related to the preservation of ancestral memory associated with social power.

Patrice Labedan, Nicolas Drougard, Alexandre Berezin et al.

The analyses of ancient coins, and especially the identification of those struck with the same die, provides invaluable information for archaeologists and historians. Nowadays, these die links are identified manually, which makes the process laborious, if not impossible when big treasures are discovered as the number of comparisons is too large. This study introduces advances that promise to streamline and enhance archaeological coin analysis. Our contributions include: 1) First publicly accessible labeled dataset of coin pictures (329 images) for die link detection, facilitating method benchmarking; 2) Novel SSIM-based scoring method for rapid and accurate discrimination of coin pairs, outperforming current techniques used in this research field; 3) Evaluation of clustering techniques using our score, demonstrating near-perfect die link identification. We provide datasets, to foster future research and the development of even more powerful tools for archaeology, and more particularly for numismatics.

Sophia Grusnis, Jamie Tayar, Diego Godoy-Rivera

Asteroseismology, the study of stellar oscillations, and stellar modeling both offer profound insights into the fundamental properties and evolution of stars. With pySYD, a new open-source Python package, we were able to constrain the asteroseismic global parameters, $ν_{max}$ and $Δν$, for 82 solar-like oscillating subgiant and lower red giant stars, filling in the region between the Kepler dwarfs and giants. Using asteroseismic scaling relations, we were able to compute seismic masses, radii, and surface gravities for our entire sample with average errors of 0.21 $M_{\bigodot}$, 0.27 $R_{\bigodot}$, and 0.06 dex respectively. Using 4 stellar modeling grids we determine and compare stellar ages for our sample. We find that our age distribution from stellar modeling is consistent with other local star samples. We find small consistent offsets from model predictions across our regime, but offsets were worse at higher gravities (log(g) $\geq$ 3.5 dex), suggesting the need for better calibration. Finally, we discuss our sample in the context of galactic archaeology and show how ages like these could be used to identify and study binary system evolution and galactic evolution in the future. All in all, we show that asteroseismology can be successfully performed with TESS data and can continue to make an impact on our understanding of stellar physics and galactic archaeology.

Huan Liu, Shashank Priya, Richard D. James

Scaling laws illuminate Nature's fundamental biological principles and guide bioinspired materials and structural designs. In simple cases they are based on the fundamental principle that all laws of nature remain unchanged (i.e., invariant) under a change of units. A more general framework is a change of variables for the governing laws that takes all equations, boundary, and interaction conditions into themselves. We consider an accepted macroscale system of partial differential equations including coupled fluid dynamics, nonlinear elasticity, and rigid body mechanics for a complex organism. We show that there is a set of scaling laws where length, time, density, elastic modulus, viscosity, and gravitational constant undergo nontrivial scaling (Table 1). We compare these results to extensive data sets mined from the literature on beating frequency of flying, swimming, and running animals, speed of bacteria, insects, fish, mammals and reptiles, leg stiffness of mammals, and modulus of elasticity of plants. The uniform agreement of the scaling laws with the dynamics of fauna, flora, and microorganisms supports the dominating role of coupled nonlinear elasticity and fluid dynamics in evolutionary development. We conclude with predictions for some prehistoric cases for which observations are unavailable.

M. McCarthy, D. P. Curley

The inspiration behind this paper came from both authors' long-term collaboration with our friend and colleague, Professor Ralph Kenna. This connection emerged initially through his interest in Rathcroghan and in our paper, `Exploring the Nature of the Fráoch Saga', which we concluded with the statement that we believed it `presents a case that will hopefully ignite conversation between disciplines'. This led us to consider the potential value for researchers of compiling a template list of useful and reliable sources and resources to consult, in other words a type of starter toolkit or guide for any individual from an alternative discipline or background, who might possess, or, in time, develop a personal or professional interest in Early Ireland and Early Irish literature. In doing this, we decided for ease of illustration, to take the example of the location name Rathcroghan/Cruachan Aí, (the prehistoric Royal Site of Connacht in the west of Ireland and the place that we both work in and interact with on a daily basis), as a case study in order to demonstrate an initial methodological approach to not only the types of resources and information available, but also to highlight some potential pitfalls that may arise in the course of an investigation.

L. Mashonkina, Yu. Pakhomov, T. Sitnova et al.

Detailed chemical abundances of very metal-poor (VMP, [Fe/H] < -2) stars are important for better understanding the First Stars, early star formation and chemical enrichment of galaxies. Big on-going and coming high-resolution spectroscopic surveys provide a wealth of material that needs to be carefully analysed. For VMP stars, their elemental abundances should be derived based on the non-local thermodynamic equilibrium (non-LTE = NLTE) line formation because low metal abundances and low electron number density in the atmosphere produce the physical conditions favorable for the departures from LTE. The galactic archaeology research requires homogeneous determinations of chemical abundances. For this purpose, we present grids of the 1D-NLTE abundance corrections for the Na I, Mg I, Ca I, Ca II, Ti II, Fe I, Zn I, Zn II, Sr II, and Ba II lines, which are used in the galactic archaeology research. The range of atmospheric parameters represents VMP stars on various evolutionary stages and covers effective temperatures from 4000 to 6500~K, surface gravities from log g = 0.5 to log g = 5.0, and metallicities $-5.0 \le$ [Fe/H] $\le -2.0$. The data is publicly available, and we provide the tools for interpolating in the grids online.

Simon Briend, Francisco Calvillo, Gábor Lugosi

We study the problem of finding the root vertex in large growing networks. We prove that it is possible to construct confidence sets of size independent of the number of vertices in the network that contain the root vertex with high probability in various models of random networks. The models include uniform random recursive dags and uniform Cooper-Frieze random graphs.

Claudia Reyes, Dennis Stello, Marc Hon et al.

Precise asteroseismic parameters allow one to quickly estimate radius and mass distributions for large samples of stars. A number of automated methods are available to calculate the frequency of maximum acoustic power ($ν_{\mathrm{max}}$) and the frequency separation between overtone modes ($Δν$) from the power spectra of red giants. However, filtering through the results requires either manual vetting, elaborate averaging across multiple methods, or sharp cuts in certain parameters to ensure robust samples of stars free of outliers. Given the importance of ensemble studies for Galactic archaeology and the surge in data availability, faster methods for obtaining reliable asteroseismic parameters are desirable. We present a neural network classifier that vets $Δν$ by combining multiple features from the visual $Δν$ vetting process. Our classifier is able to analyse large numbers of stars determining whether their measured $Δν$ are reliable thus delivering clean samples of oscillating stars with minimal effort. Our classifier is independent of the method used to obtain $ν_{\mathrm{max}}$ and $Δν$, and therefore can be applied as a final step to any such method. Tests of our classifier's performance on manually vetted $Δν$ measurements reach an accuracy of 95%. We apply the method to giants observed by K2 Galactic Archaeology Program and find that our results retain stars with astrophysical oscillation parameters consistent with the parameter distributions already defined by well-characterised Kepler red giants.

Eleanor M. L. Scerri, Marine Frouin, Paul S. Breeze et al.

Abstract The Arabian Peninsula is a critical geographic landmass situated between Africa and the rest of Eurasia. Climatic shifts across the Pleistocene periodically produced wetter conditions in Arabia, dramatically altering the spatial distribution of hominins both within and between continents. This is particularly true of Acheulean hominins, who appear to have been more tethered to water sources than Middle Palaeolithic hominins. However, until recently, chrono-cultural knowledge of the Acheulean of Arabia has been limited to one dated site, which indicated a hominin presence in Marine Isotope Stages (MIS) 7–6. Here, we report the first dated Acheulean site from the Nefud Desert of northern Saudi Arabia, together with palaeoecological evidence for an associated deep, probably fresh-water, lake. The site of An Nasim features varied and often finely flaked façonnage handaxes. Luminescence ages together with geomorphological and palaeoecological evidence indicates that the associated artefacts date to MIS 9. At present, An Nasim represents the oldest yet documented Acheulean sites in Arabia, and adds to a growing picture of regionally diverse stone tool assemblages used by Middle Pleistocene hominins, and likely indicative of repeated population re-entry into the peninsula in wet ‘Green Arabia’ phases.

Stefan Chohadzhiev

The article presents the results of a receintly excavated site near the village of Orlovets in the eastern part of present-day central north Bulgaria. The trenches had a total area of 77 sq. m, and the archaeological excavations were carried out in 2003 and 2004. The seven trenches revealed that 2-4 houses were situated on an occupied area of ca. 300-400 sq. m. Sectors of three houses related to two preserved Chalcolithic construction levels were unearthed. Artefacts dated back to the Chalcolithic, Late Antiquity (6th century) and the medieval period (13th century) were yielded by the plough soil. This paper provides a description of construction techniques, “bloodless offering”, construction of ovens and platforms, floors and wall paintings. Attention is given to various tools made from stone, bone and antler as well as to several small ceramic artefacts. Archaeozological studies reveal that the layer has yielded bones of wild boar, deer, badger and wild horse. The domestic animals are represented by cattle, sheep and goat. The focus is on the pottery comprising more than 60 complete and fragmented ceramic vessels, most found in “closed contexts”. The manufacturing techniques, the shapes and the decorative patterns as well as their parallels in Ruse, Radingrad, Ovcharovo and Vinitsa sites are described. The paper also discusses the place of the pottery assemblage from Orlovets-Erendzhika in the chronological chart within the context of the Chalcolithic in the Yantra River basin.

Jiachen Xu, Junlin Guo, James Zimmer-Dauphinee et al.

Archaeology has long faced fundamental issues of sampling and scalar representation. Traditionally, the local-to-regional-scale views of settlement patterns are produced through systematic pedestrian surveys. Recently, systematic manual survey of satellite and aerial imagery has enabled continuous distributional views of archaeological phenomena at interregional scales. However, such 'brute force' manual imagery survey methods are both time- and labor-intensive, as well as prone to inter-observer differences in sensitivity and specificity. The development of self-supervised learning methods offers a scalable learning scheme for locating archaeological features using unlabeled satellite and historical aerial images. However, archaeological features are generally only visible in a very small proportion relative to the landscape, while the modern contrastive-supervised learning approach typically yields an inferior performance on highly imbalanced datasets. In this work, we propose a framework to address this long-tail problem. As opposed to the existing contrastive learning approaches that treat the labelled and unlabeled data separately, our proposed method reforms the learning paradigm under a semi-supervised setting in order to utilize the precious annotated data (<7% in our setting). Specifically, the highly unbalanced nature of the data is employed as the prior knowledge in order to form pseudo negative pairs by ranking the similarities between unannotated image patches and annotated anchor images. In this study, we used 95,358 unlabeled images and 5,830 labelled images in order to solve the issues associated with detecting ancient buildings from a long-tailed satellite image dataset. From the results, our semi-supervised contrastive learning model achieved a promising testing balanced accuracy of 79.0%, which is a 3.8% improvement as compared to other state-of-the-art approaches.

Rouhollah Rahimi, Mojtaba Ansari

Sense of place is the factor that transforms a space into a place with special sensory and behavioural characteristicsfor individuals. Place is a sensible and perceptible space associated with memory, of which part of meaning can betraced in human experience and emotions. The key questions addressed in this article are how human beings feelthe environment through form structures, and what physical components and formal factors affect human beings’perception of a place. Finding replies to these questions requires understanding the factors and physical componentscausing sense of place and the effects of such factors and components both on creating sense of place and on oneanother. The purpose of this paper was to evaluate the effects and roles of architectural forms and structures of anenvironment on creating positive and negative emotions toward a place. To this end, we mention the meanings of suchconcepts as place, sense of place, and physical components being effective in creating sense of place, followed by anelaboration of different types of factors and components as well as their effects on creating sense of place. The datarequired for this study was collected using a descriptive-analytical research method combined with a case study onHafez Garden-Tomb in the north of Shiraz and in the south of the gates of the Quran. The results indicated that boththe physical environment and forms play important roles in creating sense of place through specific mechanisms. Inaddition, the findings of the case study showed that the structural form of Hafez Garden-Tomb consists of componentshaving effects not only on the sense associated with the place but also on other factors creating sense of place.

Barbara Drobniewicz, Bolesław Ginter

In the 1970s, the authors of this paper explored the Site 21b, situated in the north-western fringe of the Deir el-Bahari Valley, in the Theban Massif (Upper Egypt). Based on the significant variability in the state of preservation of artefacts’ surfaces, six series of artefacts were identified, corresponding to the Middle Palaeolithic and Pre-Dynastic assemblages. The most detailed analysis was performed for the inventory of the series 2, which was ascribed to a previously unknown industry with the Levallois technique and Mousterian discoidal cores. This industry is also characterised by an occurrence of a specific manner of obtaining flakes from globular and thick, flattened, lens-like nodules, abundantly occurring in the local Lower Eocene limestone. This manner of flake production was called the Bahari technique. Due to the occurrence of sidescrapers, Mousterian points, denticulated and notched pieces, the chronology of this series was determined as Middle Palaeolithic.

Blaine W. Schubert, Joshua X. Samuels, James C. Chatters et al.

Ongoing investigation of peccary remains from fossiliferous deposits in the Yucatán resulted in re-examination of previously identified tayassuid fossils from the region. This included the recently described new genus and species of peccary, 'Muknalia minima', which is based on a dentary from Muknal Cave near Tulum, Quintana Roo, Mexico. Diagnostic characters of this taxon include a concave notch along the caudal edge of the ascending ramus and a ventrally directed angular process. Our assessment of the holotype indicates that these characteristics are not a reflection of the original morphology, but are instead the result of breakage and polishing of the posterior aspect of the dentary. Measurements and intact morphological features indicate the Muknal Cave specimen belongs to the extant collared peccary, 'Pecari tajacu'.

L. Graziani, R. Schneider, S. Marassi et al.

The existence of massive stellar black hole binaries (MBHBs), with primary black hole (BH) masses $\ge 31 \, M_\odot$, was proven by the detection of the gravitational wave (GW) event GW150914 during the first LIGO/Virgo observing run (O1), and successively confirmed by seven additional GW signals discovered in the O1 and O2 data. By adopting the galaxy formation model \texttt{GAMESH} coupled with binary population synthesis (BPS) calculations, here we investigate the origin of these MBHBs by selecting simulated binaries compatible in mass and coalescence redshifts. We find that their cosmic birth rates peak in the redshift range $6.5 \leq z \leq 10$, regardless of the adopted BPS. These MBHBs are then old systems forming in low-metallicity ($Z \sim [0.01-0.1] \, Z_{\odot}$), low-stellar-mass galaxies, before the end of cosmic reionization, i.e. significantly beyond the peak of cosmic star formation. GW signals generated by coalescing MBHBs open up new possibilities to probe the nature of stellar populations in remote galaxies, at present too faint to be detected by available electromagnetic facilities.

I. Minchev, G. Matijevic, D. W. Hogg et al.

Simpson's paradox, or Yule-Simpson effect, arises when a trend appears in different subsets of data but disappears or reverses when these subsets are combined. We describe here seven cases of this phenomenon for chemo-kinematical relations believed to constrain the Milky Way disk formation and evolution. We show that interpreting trends in relations, such as the radial and vertical chemical abundance gradients, the age-metallicity relation, and the metallicity-rotational velocity relation (MVR), can lead to conflicting conclusions about the Galaxy past if analyses marginalize over stellar age and/or birth radius. It is demonstrated that the MVR in RAVE giants is consistent with being always strongly negative, when narrow bins of [Mg/Fe] are considered. This is directly related to the negative radial metallicity gradients of stars grouped by common age (mono-age populations) due to the inside out disk formation. The effect of the asymmetric drift can then give rise to a positive MVR trend in high-[alpha/Fe] stars, with a slope dependent on a given survey's selection function and observational uncertainties. We also study the variation of lithium abundance, A(Li), with [Fe/H] of AMBRE:HARPS dwarfs. A strong reversal in the positive A(Li)-[Fe/H] trend of the total sample is found for mono-age populations, flattening for younger groups of stars. Dissecting by birth radius shows strengthening in the positive A(Li)-[Fe/H] trend, shifting to higher [Fe/H] with decreasing birth radius; these observational results suggest new constraints on chemical evolution models. This work highlights the necessity for precise age estimates for large stellar samples covering wide spatial regions.

Gonzalo Castillo Alcántara, Alicia Fernández Díaz

El presente estudio pretende abordar el análisis de un conjunto de fragmentos de terra sigillata itálica provenientes de diferentes campañas de excavación realizadas en los años 1977-1978, 1995 y 2004 en el Cerro del Molinete de Cartagena y en 2006-2007 en la Villa Romana de Portmán, a fin de determinar las formas y producciones de este tipo presentes en el territorium de Carthago Nova y conocer la articulación del comercio de estas producciones entre la ciudad y el campo.

Jean-Gabriel Young, Guillaume St-Onge, Edward Laurence et al.

Network growth processes can be understood as generative models of the structure and history of complex networks. This point of view naturally leads to the problem of network archaeology: reconstructing all the past states of a network from its structure---a difficult permutation inference problem. In this paper, we introduce a Bayesian formulation of network archaeology, with a generalization of preferential attachment as our generative mechanism. We develop a sequential Monte Carlo algorithm to evaluate the posterior averages of this model, as well as an efficient heuristic that uncovers a history well correlated with the true one, in polynomial time. We use these methods to identify and characterize a phase transition in the quality of the reconstructed history, when they are applied to artificial networks generated by the model itself. Despite the existence of a no-recovery phase, we find that nontrivial inference is possible in a large portion of the parameter space as well as on empirical data.

Fiorenzo Vincenzo, Chiaki Kobayashi

We predict how the C, N, and O abundances within the interstellar medium of galaxies evolve as functions of the galaxy star formation history (SFH). We adopt a hydrodynamical cosmological simulation, focusing on three star-forming disc galaxies with different SFHs. By assuming failed supernovae, we can predict an increasing trend of the gas-phase N/O--O/H abundance diagram, which was not produced in our previous simulations without failed supernovae. At high redshifts, contrary to the predictions of classical chemical evolution models with instantaneous mixing approximation, we find almost flat trends in the N/O--O/H diagram, which are due to the contribution of intermediate-mass stars together with an inhomogeneous chemical enrichment. Finally, we also predict that the average N/O and C/O steadily increase as functions of time, while the average C/N decreases, due to the mass and metallicity dependence of the yields of asymptotic giant branch stars; such variations are more marked during more intense star formation episodes. Our predictions on the CNO abundance evolution can be used to study the SFH of disc galaxies with the James Webb Space Telescope.