54 research outputs found
A new device to mount portable energy-dispersive X-ray fluorescence spectrometers (p-ED-XRF) for semi-continuous analyses of split (sediment) cores and solid samples
Portable energy-dispersive X-ray fluorescence spectrometers (p-ED-XRF) have
become increasingly popular in sedimentary laboratories to quantify the
chemical composition of a range of materials such as sediments, soils, solid
samples, and artefacts. Here, we introduce a low-cost, clearly arranged unit
that functions as a sample chamber (German industrial property rights no. 20
2014 106 048.0) for p-ED-XRF devices to facilitate economic, non-destructive,
fast, and semi-continuous analysis of (sediment) cores or other solid samples.
The spatial resolution of the measurements is limited to the specifications of
the applied p-ED-XRF device – in our case a Thermo Scientific Niton XL3t p-ED-
XRF spectrometer with a maximum spatial resolution of 0.3 cm and equipped with
a charge-coupled device (CCD) camera to document the measurement spot. We
demonstrate the strength of combining p-ED-XRF analyses with this new sample
chamber to identify Holocene facies changes (e.g. marine vs. terrestrial
sedimentary facies) using a sediment core from an estuarine environment in the
context of a geoarchaeological investigation at the Atlantic coast of southern
Spain
On-Site VIS-NIR Spectral Reflectance and Colour Measurements - A Fast and Inexpensive Alternative for Delineating Sediment Layers Quantitatively? A Case Study from a Monumental Bronze Age Burial Mound (Seddin, Germany)
Quantitative sediment analyses performed in the laboratory are often used throughout archaeological excavations to critically reflect on-site stratigraphic delineation. Established methods are, however, often time-consuming and expensive. Recent studies suggest that systematic image analysis can objectivise the delineation of stratigraphic layers based on fast quantitative spectral measurements. The presented study examines how these assumptions prevail when compared to modern techniques of sediment analysis. We examine an archaeological cross-section at a Bronze Age burial mound near Seddin (administrative district Prignitz, Brandenburg, Germany), consisting of several layers of construction-related material. Using detailed on-site descriptions supported by quantitatively measured sediment properties as a measure of quality, we compare clustering results of (i) extensive colour measurements conducted with an RGB and a multispectral camera during fieldwork, as well as (ii) selectively sampled sedimentological data and (iii) visible and near infrared (VIS-NIR) hyperspectral data, both acquired in the laboratory. Furthermore, the influence of colour transformation to the CIELAB colour space (Commission Internationale de l’Eclairage) and the possibilities of predicting soil organic carbon (SOC) based on image data are examined. Our results indicate that quantitative spectral measurements, while still experimental, can be used to delineate stratigraphic layers in a similar manner to traditional sedimentological data. The proposed processing steps further improved our results. Quantitative colour measurements should therefore be included in the current workflow of archaeological excavations
Clinical Validation of a Digital Transcutaneous PCO2/SpO2 Ear Sensor in Adult Patients after Cardiac Surgery
Objective: The aim of this study was to validate the V-Sign digital sensor (SenTec AG, Therweil, Switzerland) for combined noninvasive assessment of pulse oxymetric oxygen saturation (SpO2) and transcutaneous carbon dioxide tension (PtcCO2) in adults after cardiac surgery. Methods: In twenty one patients, aged 51-86years, simultaneous measurements of blood gases with the V-Sign Sensor and with two Nellcor Durasensors (model DS-100A), one at the opposite earlobe and one with a finger clip, were compared first during hyper-, normo- and hypocapnia and at different pulse rates using a pacemaker, and then at 2-h intervals up to 8h. Agreement was assessed by Bland-Altman analysis. Results: PtcCO2 data of three patients were excluded because of calibration failure of the device. Median (range) PtcCO2 for the remaining patients was 5.49 (3.3-7.6) kPa and arterial carbon dioxide tension (PaCO2) was 5.43 (3.61-7.41) kPa. Corresponding mean bias was +0.05kPa and limits of agreement (LOA) were −1.2/+1.3kPa. During normo- and hypoventilation, mean bias was good at +0.02 and +0.04kPa respectively, but limits of agreement were poor at −0.67/+0.69 and −0.81/+0.88kPa. In 10 patients, an initial overshoot of PtcCO2 was observed. Mean bias of SpO2 and pulse rate was close to zero (−1.5% and +0.001bpm respectively), but limits of agreement were unacceptably high (−21.4/+18.4% and −22.3/+22.3bpm). Conclusions: In the present state of development the SenTeC Digital monitor V-Sign device has serious limitations. Additional efforts are necessary to eliminate calibration failures and the initial overshoot of PtcCO2 as well as to improve detection of SpO2 and pulse rat
Coupling spectral imaging and laboratory analyses to digitally map sediment parameters and stratigraphic layers in Yeha, Ethiopia
Quantitative analyses of soil and sediment samples are often used to complement stratigraphic interpretations in archaeological and geoscientific research. The outcome of such analyses often is confined to small parts of the examined profiles as only a limited number of samples can be extracted and processed. Recent laboratory studies show that such selectively measured soil and sediment characteristics can be spatially extrapolated using spectral image data, resulting in reliable maps of a variety of parameters. However, on-site usage of this method has not been examined. We therefore explore, whether image data (RGB data and visible and near infrared hyperspectral data), acquired under regular fieldwork conditions during an archaeological excavation, in combination with a sampling strategy that is close to common practice, can be used to produce maps of soil organic matter, hematite, calcite, several weathering indices and grain size characteristics throughout complex archaeological profiles. We examine two profiles from an archaeological trench in Yeha (Tigray, Ethiopia). Our findings show a promising performance of RGB data and its derivative CIELAB as well as hyperspectral data for the prediction of parameters via random forest regression. By including two individual profiles we are able to assess the accuracy and reproducibility of our results, and illustrate the advantages and drawbacks of a higher spectral resolution and the necessary additional effort during fieldwork. The produced maps of the parameters examined allow us to critically reflect on the stratigraphic interpretation and offer a more objective basis for layer delineation in general. Our study therefore promotes more transparent and reproducible documentation for often destructive archaeological fieldwork
Autonomous robotic nanofabrication with reinforcement learning
The ability to handle single molecules as effectively as macroscopic
building-blocks would enable the construction of complex supramolecular
structures inaccessible to self-assembly. The fundamental challenges
obstructing this goal are the uncontrolled variability and poor observability
of atomic-scale conformations. Here, we present a strategy to work around both
obstacles, and demonstrate autonomous robotic nanofabrication by manipulating
single molecules. Our approach employs reinforcement learning (RL), which finds
solution strategies even in the face of large uncertainty and sparse feedback.
We demonstrate the potential of our RL approach by removing molecules
autonomously with a scanning probe microscope from a supramolecular structure
-- an exemplary task of subtractive manufacturing at the nanoscale. Our RL
agent reaches an excellent performance, enabling us to automate a task which
previously had to be performed by a human. We anticipate that our work opens
the way towards autonomous agents for the robotic construction of functional
supramolecular structures with speed, precision and perseverance beyond our
current capabilities.Comment: 3 figure
A Comparative Analysis of Case Studies from the Old World
The present contribution deals with the concepts of marginal habitats in
selected regions of the ancient world, ranging from modern Spain to the
Jordanian desert and from Turkey to the Ethiopian highlands. Central to this
research is the hypothesis that the occupation of areas beyond the ‘normal’
settlement patterns corresponds to colonization processes which reflect
specific social strategies and may have stimulated the development of new
technological skills. A review of ‘marginality’ research in various
disciplines indicates that there is no comprehensive definition of the
concept, which can be approached from a multitude of perspectives and with
manifold objectives. A survey of the eight case studies and two more in-depth
discussions of the sites of Musawwarat (Sudan) and Ayamonte (Spain) highlight
the potentials as well as the limits of the archaeological investigation into
past marginalities. Patterns of spatial marginalization are the easiest to
detect. The studies also show that we must not limit our analysis to the
adverse factors connected to different kinds of marginalities. Instead, our
analyses suggest that spatially marginal areas were deliberately chosen for
settlement – an integration with core-periphery approaches may help us to
understand these scenarios, which have received little attention in
‘marginality’ research in archaeology or elsewhere so far
Pemetrexed with or without Matuzumab as Second-Line Treatment for Patients with Stage IIIB/IV Non-small Cell Lung Cancer
INTRODUCTION: This randomized phase II study investigated pemetrexed in combination with the epidermal growth factor receptor (EGFR)-targeting monoclonal antibody matuzumab compared with pemetrexed alone as second-line therapy for patients with advanced non-small cell lung cancer.
METHODS: Patients received pemetrexed 500 mg/m every 3 weeks either alone (n = 50) or in combination with matuzumab at either 800 mg weekly (n = 51) or 1600 mg every 3 weeks (n = 47). The primary end point was objective response, as assessed by an independent review committee.
RESULTS: Tumor EGFR expression was detected in 87% of randomized patients. The objective response rate for the pooled matuzumab-treated arms was 11% compared with 5% for pemetrexed alone (p = 0.332). Apart from one patient in the pemetrexed alone group, all responses occurred in patients whose tumors expressed EGFR. The objective response rate for patients receiving weekly matuzumab was 16% compared with 2% for those receiving matuzumab every 3 weeks. There was also a trend for improved overall survival in patients receiving matuzumab weekly versus every 3 weeks (12.4 months versus 5.9 months, respectively, versus 7.9 months for pemetrexed alone). The combination of pemetrexed and matuzumab demonstrated an acceptable safety profile, with the most common grade 3/4 adverse event being neutropenia.
CONCLUSION: Although the analysis on the pooled matuzumab-treated arms did not demonstrate a statistically significant improvement in objective response for the addition of matuzumab to pemetrexed compared with pemetrexed alone, the trends for improvement in objective response and overall survival for pemetrexed plus weekly matuzumab compared with pemetrexed alone warrant confirmation in additional clinical trials
Mouse mutant phenotyping at scale reveals novel genes controlling bone mineral density.
The genetic landscape of diseases associated with changes in bone mineral density (BMD), such as osteoporosis, is only partially understood. Here, we explored data from 3,823 mutant mouse strains for BMD, a measure that is frequently altered in a range of bone pathologies, including osteoporosis. A total of 200 genes were found to significantly affect BMD. This pool of BMD genes comprised 141 genes with previously unknown functions in bone biology and was complementary to pools derived from recent human studies. Nineteen of the 141 genes also caused skeletal abnormalities. Examination of the BMD genes in osteoclasts and osteoblasts underscored BMD pathways, including vesicle transport, in these cells and together with in silico bone turnover studies resulted in the prioritization of candidate genes for further investigation. Overall, the results add novel pathophysiological and molecular insight into bone health and disease
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