Disc formation in turbulent cloud cores: Circumventing the magnetic braking catastrophe

We present collapse simulations of strongly magnetised, 100 M_sun, turbulent cloud cores. Around the protostars formed during the collapse Keplerian discs with typical sizes of up to 100 AU build up in contrast to previous simulations neglecting turbulence. Analysing the condensations in which the discs form, we show that the magnetic flux loss is not sufficient to explain the build-up of Keplerian discs. The average magnetic field is strongly inclined to the disc which might reduce the magnetic braking efficiency. However, the main reason for the reduced magnetic braking efficiency is the highly disordered magnetic field in the surroundings of the discs. Furthermore, due to the lack of a coherently rotating structure in the turbulent environment of the disc no toroidal magnetic field necessary for angular momentum extraction can build up. Simultaneously the angular momentum inflow remains high due to local shear flows created by the turbulent motions. We suggest that the "magnetic braking catastrophe" is an artefact of the idealised non-turbulent initial conditions and that turbulence provides a natural mechanism to circumvent this problem.Comment: 4 pages, 2 figures. To appear in the proceedings of 'The Labyrinth of Star Formation' (18-22 June 2012, Chania, Greece), published by Springe

An Exploratory Spatial Analysis of the Churches in the Southern Mani Peninsula, Greece

The Mani Peninsula is home to hundreds of Orthodox Christian churches that were built within the last millennium. As in other parts of the Eastern Mediterranean countryside, the topological relationship between churches and settlements is a critical factor in understanding the significance of the sacred landscape. Many churches are situated in the central part of a village or on its very edge, but others – what are referred to as “outlying churches” or exokklisia – are built at great distances away. In this paper, we make the first attempt to assess the spatial relationship between the spaces where people worshipped (the churches) and the spaces where they lived (the settlements) at a regional scale, focused specifically on the Middle Byzantine period and later (mid-9th century CE to the present day). Comparing these patterns across the Byzantine, Ottoman, and Modern periods allows us to frame Mani’s sacred infrastructure within a changing, diachronic perspective. The results point to a change in the topological relationship between church and settlement that is best described as the “nucleation of the sacred landscape.

The Stone-Built Palaiomaniatika of the Mani Peninsula, Greece

There are over 170 stone-built settlements in the Mani Peninsula that scholars believe were inhabited from the Middle Byzantine period (eighth to thirteenth centuries AD) up until the sixteenth to seventeenth centuries. These enigmatic sites are known as palaiomaniatika, and roughly half of them are abandoned today, their massive stone walls in various stages of collapse and overgrown by olive trees and unchecked brush. This paper reviews the state of scholarship on the sites, outlining the typical characteristics of the vernacular architecture and discussing variations in settlement size and layout. A case study of the abandoned village of Koulouvades is offered to illustrate how targeted archaeological sampling and archival analysis can be fruitfully combined to illuminate the timeline of village abandonment. The final part of this paper is a call to action to archaeologists of the medieval and post-medieval eastern Mediterranean to adopt the theoretical lens of household archaeology. Through excavations of rural villages, data can be gathered that can answer questions about social process from a “bottom-up” perspective. Despite the body of art historical and architectural studies that have been carried out at the palaiomaniatika over the past 40 years, the lack of archaeological excavations limits the questions we can ask about daily life in these villages, as well as about the factors that contributed to their abandonment. Yet, they are an ideal candidate for household-scale excavations that would contribute to a wider understanding of social process in rural landscapes, not only in the Peloponnese but across the eastern Mediterranean as a whole

Review of Digital Historical Research on Southeast Europe and the Ottoman Space, edited by Dino Mujadžević (post-print)

Review of Dino Mujadžević (ed.), Digital Historical Research on Southeast Europe and the Ottoman Space, Studies on Language and Culture in Central and Eastern Europe Volume 35 (Berlin: Peter Lang, 2021). https://doi.org/10.3726/b1712

Seascapes and Fresh Water Management in Rural Greece: The Case of the Mani Peninsula, 1261–1821 CE

The Mani peninsula is a semi-arid landscape with few natural sources of fresh water, yet it supported a dense population during the Late Byzantine and Ottoman periods. This paper reviews the archaeological and historical evidence for water-management practices in Mani, concentrating on its domestic-scale hydraulic infrastructure (cisterns and saltpans) and the ports and harbours along its coasts. The data point to a critical shift in household-level social organization at the turn of the 18th century, underscoring the fact that people living in supposedly ‘peripheral’ regions like Mani nevertheless engaged in far-reaching networks of contact and exchange

The Legacy of Byzantine Christianity in the Southern Mani Peninsula, Greece, after Imperial Collapse

Religion is one of the many potential mediums for emphasizing ethnic difference and highlighting group membership. Particularly in mountainous landscapes, which are difficult for imperial or state powers to control, religion may be a key means of asserting peripherality. The residents of the Mani Peninsula, Greece, converted to Orthodox Christianity during the reign of the Byzantine Empire and maintained this religious affiliation even after Byzantine collapse in 1463 CE, when the region came under Ottoman and, later, Venetian rule. This study reviews the research on Mani’s Byzantine churches to date – much of which is published in Greek – and presents new interpretations of the religious practices of the Byzantine and post-Byzantine communities of Mani. This case study sheds light on the role of religion in rural communities and the potential reasons for religious continuity in peripheral landscapes during periods of social transformation. In particular, the firm adherence of Mani’s residents to Orthodox Christianity emphasized their ethnic difference from the ruling authorities and simultaneously undermined these authorities’ ability to assert hegemonic power in the region

Observation of Andreev bound states in bicrystal grain-boundary Josephson junctions of the electron doped superconductor LaCeCuO

We observe a zero-bias conductance peak (ZBCP) in the ab-plane quasiparticle tunneling spectra of thin film grain-boundary Josephson junctions made of the electron doped cuprate superconductor LaCeCuO. An applied magnetic field reduces the spectral weight around zero energy and shifts it non-linearly to higher energies consistent with a Doppler shift of the Andreev bound states (ABS) energy. For all magnetic fields the ZBCP appears simultaneously with the onset of superconductivity. These observations strongly suggest that the ZBCP results from the formation of ABS at the junction interfaces, and, consequently, that there is a sign change in the symmetry of the superconducting order parameter of this compound consistent with a d-wave symmetry.Comment: 9 pages, 7 figures; December 2004, accepted for publication in Phys. Rev.

Introduction

Deserted Villages: Perspectives from the Eastern Mediterranean is a collection of case studies examining the abandonment of rural settlements over the past millennium and a half, focusing on modern-day Greece with contributions from Turkey and the United States. Unlike other parts of the world, where deserted villages have benefited from decades of meticulous archaeological research, in the eastern Mediterranean better-known ancient sites have often overshadowed the nearby remains of more recently abandoned settlements. Yet as the papers in this volume show, the tide is finally turning toward a more engaged, multidisciplinary, and anthropologically informed archaeology of medieval and post-medieval rural landscapes. The inspiration for this volume was a two-part colloquium organized for the 2016 Annual Meeting of the Archaeological Institute of America in San Francisco. The sessions were sponsored by the Medieval and Post-Medieval Archaeology Interest Group, a rag-tag team of archaeologists who set out in 2005 with the dual goals of promoting the study of later material and cultural heritage and opening publication venues to the fruits of this research. The introduction to the volume reviews the state of the field and contextualizes the archaeological understanding of abandonment and post-abandonment as ongoing processes. The nine, peer reviewed chapters, which have been substantially revised and expanded since the colloquium, offer unparalleled glimpses into how this process has played out in different places. In the first half, the studies focus on long-abandoned sites that have now entered the archaeological record. In the second half, the studies incorporate archival analysis and ethnographic interviews—alongside the archaeologists’ hyper-attention to material culture—to examine the processes of abandonment and post-abandonment in real time