14,141 research outputs found
Direct Dating Indicates a Mid-Holocene Age for Archaic Rock Engravings in Arid Central Australia
Archaic rock engravings are found widely across the arid interior of Australia and are thought to represent an early pan-continental tradition. A late Pleistocene age is assumed because of extensive weathering, but attempts to test this by direct dating have been unsuccessful. We use AMS 14C dating of calcium oxalate skins covering archaic engravings at two rock shelter sites in Central Australia (Wanga East and Puritjarra), constrained by 14C dates of charcoal in sedimentary layers beneath the same engraved slabs, to show this rock art is mid-Holocene in age. Despite a limited range of simple geometric designs and uniformity across the arid interior, this corpus of rock art is not associated with the initial peopling of the Australian desert, but is a later development reflecting the dynamics of established desert societies
Apparent Violation of the Wiedemann-Franz law near a magnetic field tuned metal-antiferromagnetic quantum critical point
The temperature dependence of the interlayer electrical and thermal
resistivity in a layered metal are calculated for Fermi liquid quasiparticles
which are scattered inelastically by two-dimensional antiferromagnetic spin
fluctuations. Both resistivities have a linear temperature dependence over a
broad temperature range. Extrapolations to zero temperature made from this
linear- range give values that appear to violate the Wiedemann-Franz law.
However, below a low-temperature scale, which becomes small close to the
critical point, a recovery of this law occurs. Our results describe recent
measurements on CeCoIn near a magnetic field-induced quantum phase
transition. Hence, the experiments do not necessarily imply a non-Fermi liquid
ground state.Comment: 4 pages, 2 figures; accepted to Phys. Rev. Let
Understanding knowledge transfer in web-based B2B IT support
In managed information technology (IT) support environments, transferring solution-oriented knowledge from an IT service provider to an enterprise customer offers benefits to both firms. However, the process of inter-organisational knowledge transfer is not well understood in such complex settings where Web-based Self-service Systems (WSSs) are increasingly employed. This paper draws on findings from an interpretive study of six large multinational IT service providers to provide a staged model of after-sales knowledge transfer from an IT service provider to an enterprise customer when a WSS is used. The paper also identifies and discusses the key challenges involved at each stage.<br /
Incontinence-specific quality of life measures used in trials of treatments for female urinary incontinence: a systematic review.
This systematic review examined the use of incontinence-specific QOL measures in clinical trials of female incontinence treatments, and systematically evaluated their quality using a standard checklist.
Of 61 trials included in the review, 58 (95.1%) used an incontinence-specific QOL measure. The most commonly used were IIQ (19 papers), I-QoL (12 papers) and UDI (9 papers). Eleven papers (18.0%) used measures which were not referenced or were developed specifically for the study. The eight QOL measures identified had good clinical face validity and measurement properties.
We advise researchers to evaluate carefully the needs of their specific study, and select the QOL measure that is most appropriate in terms of validity, utility and relevance, and discourage the development of new measures. Until better evidence is available on the validity and comparability of measures, we recommend that researchers consider using IIQ or I-QOL with or without UDI in trials of incontinence treatments
Impact of the Texas Leaf-Cutting Ant (Atta texana (Buckley) (Order Hymenoptera, Family Formicidae) on a Forested Landscape
Atta texana (Buckley), the Texas leaf-cutting ant, rapidly expanded in a harvested forested landscape on sandhills characterized by droughty soils, causing mortality of planted loblolly pine (Pinus taeda (L.)). The site, composed primarily of Quartzipsamments soils classified as thermic coated Typic Quartzipsamments in the Tonkawa soil series, accounts for approximately 5,000 ha in Nacogdoches, Rusk, Panola, and San Augustine Counties in eastern Texas, USA (Dolezel 1980). These soils are characterized by low fertility, rapid permeability, and extreme acid reaction. These sandhills are resistant to erosion and are considered important ground water recharge areas. The distribution of A. texana central nest mounds and foraging areas was examined using aerial photography, digital orthophotographic quarter quadrangles (DOQQ) (scale 1:6000), and global positioning satellite (GPS) data. Plant nutrition of A. texana nesting areas was examined. Previous soil texture analysis of the central nest mound and adjacent landscapes is presented
Tectonic structure of the Mid-Atlantic Ridge near 16°30′N
Author Posting. © American Geophysical Union, 2016. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 17 (2016): 3993–4010, doi:10.1002/2016GC006514.The 16°30'N area of the Mid-Atlantic Ridge represents an area of present-day detachment faulting. Here we present shipboard bathymetric, magnetic and gravity data acquired up to 65 km from the ridge axis that reveal a varied tectonic history of this region. Magnetic data are used to calculate spreading rates and examine spreading rate variability along and across the axis. Bathymetric and gravity data are used to infer the crustal structure. A central magnetic anomaly 40% narrower than expected is observed along much of the study area. Misalignment between modern-day spreading center and magnetic anomalies indicates tectonic reorganization of the axis within the past 780 ka. Observed magnetic anomalies show a pattern of anomalous skewness consistent with rotation of magnetic vectors probably associated with detachment faulting. Relatively thin crust north of a small (∼7 km) nontransform offset coincides with a weakly magmatic spreading axis. In contrast, to the south a robust axial volcanic ridge is underlain by thicker crust. Variations in crustal structure perpendicular to the axis occur over tens of kilometers, indicating processes which occur over timescales of 1–2 Ma.National Science Foundation Grant Number: OCE-11556502017-04-2
TRYMS : the ethical and practical considerations of a double-blind placebo controlled randomised clinical trial
Chapter 8 Preparing grant applications
Before new interventions can be used in disease control programmes, it is essential that they are carefully evaluated in “field trials”, which may be complex and expensive undertakings. Descriptions of the detailed procedures and methods used in trials that have been conducted in the past have generally not been published. As a consequence, those planning such trials have few guidelines available and little access to previously accumulated knowledge. In this book the practical issues of trial design and conduct are discussed fully and in sufficient detail for the text to be used as a “toolbox” by field investigators. The toolbox has now been extensively tested through use of the first two editions and this third edition is a comprehensive revision, incorporating the many developments that have taken place with respect to trials since 1996 and involving more than 30 contributors. Most of the chapters have been extensively revised and 7 new chapters have been added
Chapter Foreword to the third edition
Before new interventions can be used in disease control programmes, it is essential that they are carefully evaluated in “field trials”, which may be complex and expensive undertakings. Descriptions of the detailed procedures and methods used in trials that have been conducted in the past have generally not been published. As a consequence, those planning such trials have few guidelines available and little access to previously accumulated knowledge. In this book the practical issues of trial design and conduct are discussed fully and in sufficient detail for the text to be used as a “toolbox” by field investigators. The toolbox has now been extensively tested through use of the first two editions and this third edition is a comprehensive revision, incorporating the many developments that have taken place with respect to trials since 1996 and involving more than 30 contributors. Most of the chapters have been extensively revised and 7 new chapters have been added
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