19,010 research outputs found
Luminescence dating of wind-blown sands from the Broo Peninsula, Shetland
This report provides a temporal framework to support University of Stirling geo-archaeological investigations near Huesbreck, Broo Pennisula (Shetland), examining how the early modern population there, adapted to harsh climate conditions in the 18-19th centuries, when enhanced aeolian activity led to an influx of sand to the area, leading to adaptionâs in farming practices, and abandonment of several sites. Five sediment samples were submitted to the luminescence laboratories at SUERC for dating.
All samples were subjected to laboratory preparation of sand-sized quartz, and purity checked using scanning electron microscopy. Dose rates for the bulk sediment were evaluated using analyses of the uranium, thorium and potassium concentrations obtained by high resolution gamma spectrometry coupled with beta dose rate measurement using thick source beta counting, and in situ field gamma spectroscopy. Equivalent doses were determined by OSL from 32 aliquots of quartz per sample using the quartz single-aliquot-regenerative (SAR) procedure. The material exhibited good OSL sensitivity and produced acceptable SAR internal quality control performance. Radial plotting methods revealed good internal homogeneity in the dose distributions obtained for each sample.
The chronology established for the sampled sands on the site spans from the mid 16th century (AD 1540 ± 40; SUTL2441) through to the early 19th century (AD 1810 ± 25), with the dates falling within three clusters - the waning stages of the Little Ice Age, the mid 18th century (AD 1730 ± 25 to 1760 ± 25) and the early 19th century (AD 1810 ± 25). In the wider region, periods of sand movement and deposition in the mid 18th century, and early to late 18th century, are documented in sediment statigraphies sectioned at the Old Scatness Broch, Scatness
mizar-items: Exploring fine-grained dependencies in the Mizar Mathematical Library
The Mizar Mathematical Library (MML) is a rich database of formalized
mathematical proofs (see http://mizar.org). Owing to its large size (it
contains more than 1100 "articles" summing to nearly 2.5 million lines of text,
expressing more than 50000 theorems and 10000 definitions using more than 7000
symbols), the nature of its contents (the MML is slanted toward pure
mathematics), and its classical foundations (first-order logic, set theory,
natural deduction), the MML is an especially attractive target for research on
foundations of mathematics. We have implemented a system, mizar-items, on which
a variety of such foundational experiements can be based. The heart of
mizar-items is a method for decomposing the contents of the MML into
fine-grained "items" (e.g., theorem, definition, notation, etc.) and computing
dependency relations among these items. mizar-items also comes equipped with a
website for exploring these dependencies and interacting with them.Comment: Accepted at CICM 2011: Conferences in Intelligent Computer
Mathematics, Track C: Systems and Project
Near-infrared and X-ray obscuration to the nucleus of the Seyfert 2 galaxy NGC 3281
We present the results of a near-infrared and X-ray study of the Seyfert 2
galaxy NGC 3281. Emission from the Seyfert nucleus is detected in both regions
of the electromagnetic spectrum, allowing us to infer both the equivalent line
of sight hydrogen column density, N_H = 71.0(+11.3,-12.3)e26/m^2 and the
extinction due to dust, A_V = 22+/-11 magnitudes (90% confidence intervals). We
infer a ratio of N_H/A_V which is an order of magnitude larger than that
determined along lines of sight in the Milky Way and discuss possible
interpretations. We consider the most plausible explanation to be a dense cloud
in the foreground of both the X-ray and infrared emitting regions which
obscures the entire X-ray source but only a fraction of the much larger
infrared source.Comment: 23 pages including 9 figure
Linking specification to differentiation:From proneural genes to the regulation of ciliogenesis
Much of developmental biology is concerned with the processes by which cells become committed to particular fates in a regulated fashion, whereas cell biology addresses, among other things, the variety of differentiated forms and functions that cells can acquire. One open question is how the regulators of the former process lead to attainment of the latter. âHigh-levelâ regulators of cell fate specification include the proneural factors, which drive cells to commit as precursors in the sensory nervous system. Recent research has concentrated on the gene expression events downstream of proneural factor function. Here we summarize this research and describe our own research that has provided clear links between a proneural factor, atonal and the cell biological program of ciliogenesis, which is a central aspect of sensory neuron differentiation
Transcutaneous electrical nerve stimulation for cancer pain in adults.
Background Cancer-related pain is complex and multi-dimensional but the mainstay of cancer pain management has predominately used a biomedical approach. There is a need for non-pharmacological and innovative approaches. Transcutaneous Electric Nerve Stimulation (TENS) may have a role for a significant number of patients but the effectiveness of TENS is currently unknown. Objectives The aim of this systematic review was to determine the effectiveness of TENS for cancer-related pain in adults. Search strategy We searched The Cochrane Library, MEDLINE, EMBASE, CINAHL, PsychINFO, AMED and PEDRO databases (11/04/08). Selection criteria Only randomised controlled trials (RCTS) investigating the use of TENS for the management of cancer-related pain in adults were included. Data collection and analysis The search strategy identified 37 possible published studies which were divided between two pairs of review authors that decided on study selection. A study eligibility form was used to screen each abstract and where study eligibility could not be determined from the abstract, the full paper was obtained and assessed by one pair of review authors. A standardised data extraction sheet was used to collect information on the studies and the quality of the studies was assessed independently by two review authors using the validated five-point Oxford Quality Scale. Final scores were discussed and agreed between all four review authors. The small sample sizes and differences in patient study populations of the two included studies prevented meta-analysis. Main results Only two RCTs met the eligibility criteria (64 participants). These studies were heterogenous with respect to study population, sample size, study design, methodological quality, mode of TENS, treatment duration, method of administration and outcome measures used. In one RCT, there were no significant differences between TENS and placebo in women with chronic pain secondary to breast cancer treatment. In the other RCT, there were no significant differences between acupuncture-type TENS and sham in palliative care patients; this study was underpowered. Authors' conclusions The results of this systematic review are inconclusive due to a lack of suitable RCTs. Large multi-centre RCTs are required to assess the value of TENS in the management of cancer-related pain in adults
Beta event-related desynchronization as an index of individual differences in processing human facial expression: further investigations of autistic traits in typically developing adults
The human mirror neuron system (hMNS) has been associated with various forms of social cognition and affective processing including vicarious experience. It has also been proposed that a faulty hMNS may underlie some of the deficits seen in the autism spectrum disorders (ASDs). In the present study we set out to investigate whether emotional facial expressions could modulate a putative EEG index of hMNS activation (mu suppression) and if so, would this differ according to the individual level of autistic traits [high versus low Autism Spectrum Quotient (AQ) score]. Participants were presented with 3 s films of actors opening and closing their hands (classic hMNS mu-suppression protocol) while simultaneously wearing happy, angry, or neutral expressions. Mu-suppression was measured in the alpha and low beta bands. The low AQ group displayed greater low beta event-related desynchronization (ERD) to both angry and neutral expressions. The high AQ group displayed greater low beta ERD to angry than to happy expressions. There was also significantly more low beta ERD to happy faces for the low than for the high AQ group. In conclusion, an interesting interaction between AQ group and emotional expression revealed that hMNS activation can be modulated by emotional facial expressions and that this is differentiated according to individual differences in the level of autistic traits. The EEG index of hMNS activation (mu suppression) seems to be a sensitive measure of the variability in facial processing in typically developing individuals with high and low self-reported traits of autism
Biochemical diagnosis of ventricular dysfunction in elderly patients in general practice: observational study
Objective: To investigate the usefulness of measuring plasma concentrations of B type natriuretic peptide in the diagnosis of left ventricular systolic dysfunction in an unselected group of elderly people.
Design: Observational study.
Setting: General practice with four centres in Poole, Dorset.
Participants: 155 elderly patients aged 70 to 84 years.
Main outcome measures: Diagnostic characteristics of plasma B type natriuretic peptide measured by radioimmunoassay as a test for left ventricular systolic dysfunction assessed by echocardiography.
Results: The median plasma concentration of B type natriuretic peptide was 39.3 pmol/l in patients with left ventricular systolic dysfunction and 15.8 pmol/l in those with normal function. The proportional area under the receiver operator curve was 0.85. At a cut-off point of 18.7 pmol/l the test sensitivity was 92% and the predictive value 18%.
Conclusions: Plasma concentration of B type natriuretic peptide could be used effectively as an initial test in a community screening programme and, possibly, using a low cut-off point, as a means of ruling out left ventricular systolic dysfunction. It is, however, not a good test to ârule inâ the diagnosis, and access to echocardiography remains essential for general practitioners to diagnose heart failure early
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