2,355 research outputs found
Copper processing in the oases of northwest Arabia: technology, alloys and provenance
Very little is known about early metallurgical activity in the north-western part of the Arabian Peninsula, despite the region’s cultural importance. To begin to address this research lacuna, metallurgical remains including crucible fragments, metal dross and a copper artefact were sampled from two oases in northwest Arabia, Qurayyah and Tayma. The metallurgical activity in Qurayyah is dated to the Late Bronze Age, and in Tayma to the Roman/Late Roman period. At both sites we identified evidence for copper alloying and refining. Small scale copper smelting might also have been practiced in Qurayyah. Arsenical copper was processed at both sites, but in Tayma tin bronze and leaded tin bronze dominated. The chemical analysis of metal prills in crucible linings showed that fresh copper and tin instead of scrap metal were employed in these processes. Lead isotope analysis indicates that at least some of the Tayma metal was imported. Access to raw materials from remote areas is consistent with the importance of Tayma in the trading network of northwest Arabia
Stationkeeping of an L₂ Libration Point Satellite with θ-D Technique
A new method for L2 libration-point orbit stationkeeping is proposed in this paper using continuous thrust. The circular restricted three-body problem with Sun and Earth as the two primaries is considered. The unstable orbit about the L2 libration-point requires stationkeeping maneuvers to maintain the nominal path. In this study, an approach, called the θ-D technique, based on optimal control theory gives a closed-form suboptimal feedback solution to solve this nonlinear control problem. In this approach the Hamiltonian-Jacobi-Bellman (HJB) equation is solved approximately by adding some perturbations to the cost function. The controller is designed such that the actual trajectory tracks a predetermined reference orbit with good accuracy. Numerical results employing this method demonstrate the potential of this method
Repealing the Çatalhöyük extractive metallurgy: The green, the fire and the ‘slag’
The scholarly quest for the origins of metallurgy has focused on a broad region from the Balkans to Central Asia, with different scholars advocating a single origin and multiple origins, respectively. One particular find has been controversially discussed as the potentially earliest known example of copper smelting in western Eurasia, a copper ‘slag’ piece from the Late Neolithic to Chalcolithic site of Çatalhöyük in central Turkey. Here we present a new assessment of metal making at Çatalhöyük based on the re-analysis of minerals, mineral artefacts and high-temperature materials excavated in the 1960s by J. Mellaart and first analysed by Neuninger, Pittioni and Siegl in 1964. This paper focuses on copper-based minerals, the alleged piece of metallurgical slag, and copper metal beads, and their contextual relationship to each other. It is based on new microstructural, compositional and isotopic analyses, and a careful re-examination of the fieldwork documentation and analytical data related to the c. 8500 years old high-temperature debris at Çatalhöyük. We re-interpret the sample identified earlier as metallurgical slag as incidentally fired green pigment, which was originally deposited in a burial and later affected by a destructive fire that also charred the bones of the interred body. We also re-confirm the contemporary metal beads as made from native metal. Our results provide a new and conclusive explanation of the previously contentious find, and reposition Çatalhöyük in a new narrative of the multiple origins of metallurgy in the Old World.Qatar Foundation enabled the new study of this material through its generous funding of UCL Qatar as a joint centre of excellence for Museology, Conservation and Archaeolog
Challenging the Boom and Bust models? The 4th millennium BC copper mine of Curak in southwest Serbia
This paper presents groundbreaking evidence of the first copper mining in
the Balkans that occurred during the apparent metal production ‘bust’
and societal collapse in the 4th millennium BC. The copper mine at Curak
in southwest Serbia was exploited from c. 3800 cal BC and an integrated
approach encompassing a detailed survey of the area, field excavations
and a suite of provenance analyses was applied in identification of its
activities. The paper then evaluates the results against the recently
published and now extensive data surrounding early copper mining across
Europe to explore models of technological transmission and metal
production
The changing nature of labour regulation: the distinctiveness of the National Agreement for the Engineering Construction Industry
The article addresses the changing nature of labour regulation through analysis of the National Agreement for the Engineering Construction Industry, originating in 1981. It shows how multiple spatial regulatory scales, the changing coalitions of actors involved, employer and client engagement and labour agency have been critical to National Agreement for the Engineering Construction Industry's survival
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Search for physics beyond the standard model in events with τ leptons, jets, and large transverse momentum imbalance in pp collisions at [Formula: see text].
A search for physics beyond the standard model is performed with events having one or more hadronically decaying τ leptons, highly energetic jets, and large transverse momentum imbalance. The data sample corresponds to an integrated luminosity of 4.98 fb-1 of proton-proton collisions at [Formula: see text] collected with the CMS detector at the LHC in 2011. The number of observed events is consistent with predictions for standard model processes. Lower limits on the mass of the gluino in supersymmetric models are determined
Evidence for Direct CP Violation in B0 -> K+- pi-+ Decays
We report evidence for direct CP violation in the decay B0 -> K+-pi-+ with
253/fb of data collected with the Belle detector at the KEKB e+e- collider.
Using 275 million B B_bar pairs we observe a B -> K+-pi-+ signal with 2140+-53
events. The measured CP violating asymmetry is Acp(K+-pi-+) = -0.101+-0.025
(stat)+-0.005 (syst), corresponding to a significance of 3.9 sigma including
systematics. We also search for CP violation in the decays B+- -> K+-pi0 and
B+- -> pi+-pi0. The measured CP violating asymmetries are Acp(K+-pi0) =
0.04+-0.05(stat)+-0.02(syst) and Acp(pi+-pi0) = -0.02+-0.10(stat)+-0.01(syst),
corresponding to the intervals -0.05 < Acp(K+-pi0) < 0.13 and
-0.18<Acp(pi+-pi0)<0.14 at 90% confidence level.Comment: 9 pages, 3 figures. submitted to Physical Review Letter
Impacts of the First Year of COVID-19 on Food Security in the New York’s Capital Region
The COVID-19 pandemic has disrupted people\u27s lives and food systems in the United States and worldwide, resulting in impacts on different aspects of food security. To understand how this has affected households in New York’s Capital Region, we conducted two concurrent anonymous online surveys between October 2020 and February 2021. Combined, 1049 people responded to these surveys.
We report on respondents\u27 food security experiences since the COVID-19 pandemic started in New York State (March 7, 2020) compared to the prior year. We further explore the differential impacts of the pandemic on food security experiences by race and ethnicity, household income, job disruptions, and households with and without children
Measurement of the branching ratios of the decays Xi0 --> Sigma+ e- nubar and anti-Xi0 --> anti-Sigma+ e+ nu
From 56 days of data taking in 2002, the NA48/1 experiment observed 6316 Xi0
--> Sigma+ e- nubar candidates (with the subsequent Sigma+ --> p pi0 decay) and
555 anti-Xi0 --> anti-Sigma+ e+ nu candidates with background contamination of
215+-44 and 136+-8 events, respectively. From these samples, the branching
ratios BR(Xi0 --> Sigma+ e- nubar)= (2.51+-0.03stat+-0.09syst)E(-4) and
BR(anti-Xi0 --> anti-Sigma+ e+ nu)= (2.55+-0.14stat+-0.10syst)E(-4) were
measured allowing the determination of the CKM matrix element |Vus| =
0.209+0.023-0.028. Using the Particle Data Group average for |Vus| obtained in
semileptonic kaon decays, we measured the ratio g1/f1 = 1.20+-0.05 of the
axial-vector to vector form factors.Comment: 16 pages, 11 figures Submitted to Phys.Lett.
Belle II Technical Design Report
The Belle detector at the KEKB electron-positron collider has collected
almost 1 billion Y(4S) events in its decade of operation. Super-KEKB, an
upgrade of KEKB is under construction, to increase the luminosity by two orders
of magnitude during a three-year shutdown, with an ultimate goal of 8E35 /cm^2
/s luminosity. To exploit the increased luminosity, an upgrade of the Belle
detector has been proposed. A new international collaboration Belle-II, is
being formed. The Technical Design Report presents physics motivation, basic
methods of the accelerator upgrade, as well as key improvements of the
detector.Comment: Edited by: Z. Dole\v{z}al and S. Un
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