Acoustic positioning for space processing experiments

An acoustic positioning system is described that is adaptable to a range of processing chambers and furnace systems. Operation at temperatures exceeding 1000 C is demonstrated in experiments involving the levitation of liquid and solid glass materials up to several ounces in weight. The system consists of a single source of sound that is beamed at a reflecting surface placed a distance away. Stable levitation is achieved at a succession of discrete energy minima contained throughout the volume between the reflector and the sound source. Several specimens can be handled at one time. Metal discs up to 3 inches in diameter can be levitated, solid spheres of dense material up to 0.75 inches diameter, and liquids can be freely suspended in l-g in the form of near-spherical droplets up to 0.25 inch diameter, or flattened liquid discs up to 0.6 inches diameter. Larger specimens may be handled by increasing the size of the sound source or by reducing the sound frequency

Levitation of objects using acoustic energy

Activated sound source establishes standing-wave pattern in gap between source and acoustic reflector. Solid or liquid material introduced in region will move to one of the low pressure areas produced at antinodes and remain suspended as long as acoustic signal is present

Building Knowledge from Experience: Reflective Thinking as a Mediating Process for Collaborative Knowledge Building

This paper describes a model for analysing collaborative knowledge building (CKB) process during a group activity. Singh et al’s (2007) model of CKB process is used for analysing the process using data from an educational case. The concept of CKB activity system is developed based on the constructs of activity theory for analysing the case. The analysis of the case used constructs from reflective thinking to highlight the processes used by participants to collaboratively build knowledge. The findings of the study identified four additional cycles of reflective thinking activities that have been used to modify the CKB process model. The four additional cycles represent the mediating processes and tools used by the participants to build knowledge. The modified model of a CKB process together with the CKB activity system can be used as the unit of analysis for developing a cohesive theory for understanding and analysing CKB

Late Quaternary (Upper Palaeolithic, Mesolithic and Later Prehistoric) Human Activity in the Darent Valley at Lullingstone Country Park, Eynsford, Kent

Between 2009 and 2011, Archaeology South-East carried out a series of excavations and watching briefs in advance of development at the Lullingstone Country Park, near Eynsford, Kent. The work, commissioned by Kent County Council, revealed a deep sequence of Pleistocene and Holocene slope deposits in the Darent river valley. In the upper part of this sequence high-resolution and apparently in situ stone artefacts were recovered which spanned the end of the last glacial period and into the Early Holocene. Key findings include a rich cluster of refitting Terminal Upper Palaeolithic flint artefacts characteristic of Lateglacial hunter-gatherer 'longblade'cultures and a more diffuse spread of Early Mesolithic flintwork, including microliths, as part of a preserved land surface. In addition later Neolithic and Bronze Age flintwork was found within and on the surface of Holocene colluvial deposits. Deeper geoarchaeological survey revealed these archaeologically-rich surface deposits were only the upper part of a deep sequence of sediments which spanned a period in excess of 100,000 years. At the base of this sequence, at 4m depth, organic deposits likely to date to the last interglacial period were recovered. These were overlain by cold climate solifluction deposits and in turn Holocene deposits which include Bronze Age bank and ditch features. Stone artefact refitting was targeted at the Terminal Upper Palaeolithic and Mesolithic material, giving insights into the technology and behaviour of hunter-gatherers occupying southern Britain at the transition between the last ice age and the emerging world of the Holocene

Postflight analysis of the single-axis acoustic system on SPAR VI and recommendations for future flights

The single axis acoustic levitator that was flown on SPAR VI malfunctioned. The results of a series of tests, analyses, and investigation of hypotheses that were undertaken to determine the probable cause of failure are presented, together with recommendations for future flights of the apparatus. The most probable causes of the SPAR VI failure were lower than expected sound intensity due to mechanical degradation of the sound source, and an unexpected external force that caused the experiment sample to move radially and eventually be lost from the acoustic energy well

CSCW: The development of a taxonomy

Computer supported cooperative work (CSCW) is a research field that studies the use of computer technology for group work. A review of the CSCW literature found that the use of terminology and definitions were inconsistent. This paper reports on the process of development of an holistic taxonomy of terminology and related definitions used in the CSCW literature from 1996 to 2003. The taxonomic structure will provide a framework for classifying the terminology and defining each concept to improve communication in this field. The completed structure will be presented to other researchers to determine implications for research practice

Stepping stones to the Neolithic? Radiocarbon dating the Early Neolithic on islands within the ‘western seaways’ of Britain

The western seaways – an arc of sea stretching from the Channel Islands in the south, up through the Isles of Scilly, the Isle of Man and the Outer Hebrides to Orkney in the north – have long been seen as crucial to our understanding of the processes which led to the arrival of the Neolithic in Britain and Ireland in the centuries around 4000 BC. The western seaways have not, however, been considered in detail within any of the recent studies addressing the radiocarbon chronology of the Earliest Neolithic in that wider region. This paper presents a synthesis of all existing 5th and 4th millennia cal BC radiocarbon dates from islands within the western seaways, including 50 new results obtained specifically for this study. While the focus here is insular in a literal sense, the project’s results have far reaching implications for our understanding of the Mesolithic-Neolithic transition across Britain and Ireland and beyond. The findings broadly fit well with Whittle et al.’s (2011) Gathering Time model, suggesting that the earliest dated Neolithic in this zone falls into the c. 3900-3700 cal BC bracket. However, it is also noted that our current chronological understanding is based on comparatively few dates spread across a large area. Consequently, it is suggested that both further targeted work and an approach that incorporates an element of typo-chronology (as well as absolute dating) is necessary if we are to move our understanding of the process of transition in this key region forward

Mesolithic and late neolithic/Bronze Age activity on the site of the American Express Community Stadium, Falmer, East Sussex

Excavations on the site of the American Express Community Stadium, Falmer, East Sussex have revealed evidence for over 7,000 years of human activity. The earliest occupation was a mesolithic camp, where the production of flint tools (microliths) was carried out, on a scale unprecedented in East Sussex. There was little recognisable human activity in the early and middle neolithic but geoarchaeological investigations have shown that the landscape continued to change, with probable deforestation causing colluvial deposition within the river valley to the west. In the late neolithic/Early Bronze Age, a series of three ring ditches were dug, close to the location of the mesolithic pits. There are a number of possibilities as to what these ring ditches represent, but the most likely explanation is a group of barrows or other type of ceremonial ring ditch. Whatever their function, the structures were re-visited later in prehistory, a testament to the continued topographic importance of the site. Finally the site became the focus of Anglo-Saxon habitation, including a sunken-featured building, perhaps an outlying part of the precursor to Falmer village

Microliths and maritime mobility: a continental European-style Late Mesolithic flint from the Isles of Scilly

Once Britain had become separated from the European mainland in the seventh millennium BC, Mesolithic stone tool traditions on opposite sides of the newly formed Channel embarked upon different directions of development. Patterns of cross-Channel contact have been difficult to decipher in this material, prior to the expansion of farming (and possibly farmers) from northern France at the beginning of the fourth millennium BC. Hence the discovery of Late Mesolithic microliths of apparently Belgian affinity at the western extremity of southern Britain in the Isles of Scilly comes as something of a surprise. The find is described here in detail, along with alternative scenarios that might explain it. The article is followed by a series of comments, with a closing reply from the authors