Aspects of the earliest copper metalallurgy in the northern sub-alpine area in its cultural setting

The earliest copper-based objects in Switzerland, south Germany, and Austria, were studied in their cultural contexts. The chronological and spatial distributions of the relevant Late Neolithic cultures in this area, and all available material evidence were investigated, and their relationships with one another, and with neighbouring cultures, were examined.A first copper-using horizon was found to be followed by a discontinuity (second horizon) in which the use of copper was less frequent. This discontinuity was coeval with the considerable break in the pattern of copper-using cultures in northern Europe just before the beginning of the Corded Ware culture. The second horizon was succeeded by a third copper-using horizon which again used copper intensively. This latter horizon continued, particularly in Switzerland, without a break into the Bronze Age.About one hundred samples of metal objects from Swiss and Austrian museums were analysed for the first time for eleven elements, mainly by neutron activation analysis and atomic absorption spectroscopy. Some samples of objects which had been previously analysed elsewhere, and three international standards, were also analysed to establish comparability of results. In addition, 330 published analyses possibly pertaining to the Late Neolithic period were considered, chosen primarily because the artifacts concerned were of types occuring in secure Late Neolithic associations.The impurity patterns of objects containing less than 2% tin (about 360) and those containing more than 2% tin (the bronzes) were grouped separately by cluster analysis, using a computer program. Ten main copper groups, and six bronze groups, emerged, all coherent and sharply defined. They are discussed in terms of their composition, their archaeological, chronological and geographical significance. One of the three earliest coppers contained significant amounts of arsenic, and probably came from outside the region. By the third copper-using horizon there is strong evidence for mining and smelting in several areas within the Salzach region. This mined copper was mostly used in Switzerland, suggesting that Swiss groups or individuals procured their copper from Austria.It is concluded that the introduction of copper into the northern alpine region is due, not to a single culture, but to a complex net¬ work of multiple contacts and that this resulted not in one single culture which was the earliest to use copper, but in an entire early copper-using horizon. The start of the metal-using horizon was very soon followed by local smithing and also mining activities. The implications in terms of social structure, independent invention, and possible trade are briefly discussed

An all-optical trap for a gram-scale mirror

We report on a stable optical trap suitable for a macroscopic mirror, wherein the dynamics of the mirror are fully dominated by radiation pressure. The technique employs two frequency-offset laser fields to simultaneously create a stiff optical restoring force and a viscous optical damping force. We show how these forces may be used to optically trap a free mass without introducing thermal noise; and we demonstrate the technique experimentally with a 1 gram mirror. The observed optical spring has an inferred Young's modulus of 1.2 TPa, 20% stiffer than diamond. The trap is intrinsically cold and reaches an effective temperature of 0.8 K, limited by technical noise in our apparatus.Comment: Major revision. Replacement is version that appears in Phy. Rev. Lett. 98, 150802 (2007

Recent results of a seismically isolated optical table prototype designed for advanced LIGO

The Horizontal Access Module Seismic Attenuation System (HAM-SAS) is a mechanical device expressly designed to isolate a multipurpose optical table and fit in the tight space of the LIGO HAM Ultra-High-Vacuum chamber. Seismic attenuation in the detectors' sensitivity frequency band is achieved with state of the art passive mechanical attenuators. These devices should provide an attenuation factor of about 70dB above 10Hz at the suspension point of the Advanced LIGO triple pendulum suspension. Automatic control techniques are used to position the optical table and damp rigid body modes. Here, we report the main results obtained from the full scale prototype installed at the MIT LIGO Advanced System Test Interferometer (LASTI) facility. Seismic attenuation performance, control strategies, improvements and limitations are also discussed

Sea anemones may thrive in a high CO2 world

Increased seawater pCO 2, and in turn 'ocean acidification' (OA), is predicted to profoundly impact marine ecosystem diversity and function this century. Much research has already focussed on calcifying reef-forming corals (Class: Anthozoa) that appear particularly susceptible to OA via reduced net calcification. However, here we show that OA-like conditions can simultaneously enhance the ecological success of non-calcifying anthozoans, which not only play key ecological and biogeochemical roles in present day benthic ecosystems but also represent a model organism should calcifying anthozoans exist as less calcified (soft-bodied) forms in future oceans. Increased growth (abundance and size) of the sea anemone (Anemonia viridis) population was observed along a natural CO 2 gradient at Vulcano, Italy. Both gross photosynthesis (P G) and respiration (R) increased with pCO 2 indicating that the increased growth was, at least in part, fuelled by bottom up (CO 2 stimulation) of metabolism. The increase of P G outweighed that of R and the genetic identity of the symbiotic microalgae (Symbiodinium spp.) remained unchanged (type A19) suggesting proximity to the vent site relieved CO 2 limitation of the anemones' symbiotic microalgal population. Our observations of enhanced productivity with pCO 2, which are consistent with previous reports for some calcifying corals, convey an increase in fitness that may enable non-calcifying anthozoans to thrive in future environments, i.e. higher seawater pCO 2. Understanding how CO 2-enhanced productivity of non- (and less-) calcifying anthozoans applies more widely to tropical ecosystems is a priority where such organisms can dominate benthic ecosystems, in particular following localized anthropogenic stress. © 2012 Blackwell Publishing Ltd

In situ measurement of absorption in high-power interferometers by using beam diameter measurements

We present a simple technique to make in situ measurements of the absorption in the optics of high-power laser interferometers. The measurement is particularly useful to those commissioning large-scale high power optical systems.David Ottaway, Joseph Betzwieser, Stefan Ballmer, Sam Waldman and William Kell

Harnessing the power of complex light propagation in multimode fibers for spatially resolved sensing

The propagation of coherent light in multimode optical fibers results in a speckled output that is both complex and sensitive to environmental effects. These properties can be a powerful tool for sensing, as small perturbations lead to significant changes in the output of the fiber. However, the mechanism to encode spatially resolved sensing information into the speckle pattern and the ability to extract this information is thus far unclear. In this paper, we demonstrate that spatially dependent mode coupling is crucial to achieving spatially resolved measurements. We leverage machine learning to quantitatively extract this spatially resolved sensing information from three fiber types with dramatically different characteristics and demonstrate that the fiber with the highest degree of spatially dependent mode coupling provides the greatest accuracy.Comment: 17 pages and 7 figure

Air-clad holmium-doped silica fiber laser

Date of Publication : 10 December 2015We report the design, fabrication, and operation of an air-clad holmium-doped fiber laser that was manufactured by directly milling the rare-earth-doped preform. This silica fiber laser operates at 2.1 μm with a slope efficiency of 49.7%, and is in-band pumped with a 1.94-μm thulium fiber laser. To the best of our knowledge, this is the first demonstration of an air-clad holmium-doped fiber laser.Sebastian W. S. Ng, David G. Lancaster, Tanya M. Monro, Peter C. Henry, and David J. Ottawa