764 research outputs found
Mobility of daughter elements of U-238 decay chain during leaching by In Situ Recovery (ISR) : New insights from digital autoradiography
In highly permeable sedimentary rock formations, U extraction by in-situ leaching techniques (ISR - In-Situ Recovery) is generally considered to have a limited environmental impact at ground level. Significantly, this method of extraction produces neither mill tailings nor waste rocks. Underground, however, the outcome for U-238 daughter elements in aquifers is not well known because of their trace concentrations in the host rocks. Thus, understanding the in-situ mobility of these elements remains a challenge. Two samples collected before and after six months of ISR experiments (Dulaan Uul, Mongolia) were studied with the help of a digital autoradiography technique (DA) of alpha particles, bulk alpha spectrometry, and complementary petrographic observation methods. These techniques demonstrate that before and after leaching, the radioactivity is concentrated in altered and microporous Fe-Ti oxides. Most of the daughter elements of U remain trapped in the rock after the leaching process. DA confirms that the alpha activity of the Fe-Ti oxides remains high after uranium leaching, and the initial secular equilibrium of the U-238 series for Th-230 to Po-210 daughter elements (including Ra-226) of the fresh rocks is maintained after leaching. While these findings should be confirmed by more systematic studies, they already identify potential mechanisms explaining why the U-daughter concentrations in leaching water are low.Peer reviewe
Assessment of pain symptoms and quality of life using the International Spinal Cord Injury Data Sets in persons with chronic spinal cord injury
Introduction: Traumatic spinal cord injury (SCI) triggers complex changes that can negatively impact health and quality of life. The International SCI Data Sets were developed to enable more comparable data collection on the complex sequelae of SCI across studies. This should facilitate progress in mechanistic understanding and improving treatments of SCI. Study design: Prospective observational pilot study. Objectives: To collect data on pain symptoms and quality of life (QoL) in adults living with chronic SCI. Setting: Academic medical center, New York, USA. Methods: The International SCI Basic Pain and Qol Data Sets were used to collect data from participants with chronic SCI (N = 31) at 2 study visits held 6 months apart. The QoL Data Set was also used to collect data from able-bodied persons of similar age and gender distribution (N = 28). Results: Most participants with SCI had multiple types and locations of pain problems at both study visits, despite reported being treated for pain. At both visits, the worst pain problem type was nociceptive, followed by neuropathic, which was typically rated of higher intensity. QoL scores were significantly lower across all domains of the data set in persons with SCI than able-bodied persons. Persons with pain tended to have lower QoL scores, although this trend was not significant. Conclusions: This study demonstrates the presence, complexity and stability of pain symptoms refractory to treatment and lower quality of life ratings in persons with chronic SCI. Sponsorship: Grants from the Craig H. Neilsen Foundation, New York Empire Clinical Research Program, New York State Spinal Cord Injury Research Board
Historia de los Papas desde San Pedro hasta nuestros días
Contiene: T. I, II, III y VDonación J. L. Estrada (Biblioteca General)Digitalizada en formato pdf tomos 1, 2 y 5
Taxonomic and nomenclatural notes on the coccolithophore Gephyrocapsa huxleyi (Noelaerhabdaceae, Haptophyta) and related species
Illite-smectite mixed-layer minerals in hydrothermal alteration of volcanic rocks: I. One-dimensional XRD structure analysis and characterisation of component layers.
International audienceFor a series of mixed-layer illite-smectite (I-S) minerals from a drill hole near the Kakkonda geothermal field, one-dimensional structure analysis by X-ray diffraction (XRD) was performed using Ca-saturated specimens at both air-dried and ethylene glycol solvated states. The expandability characteristics of component layers were also examined by means of alkylammonium exchange and Li-saturation. The K content in illite layer was almost constant at 1.5-1.7/O20(OH)4 in the I-S series from 3% to 85% of I-layer content (% I). The layer charge of smectite layer varied slightly within the ranges of R1 I-S samples showed complicated expandability with alkylammonium exchange. The XRD patterns of dodecylammonium exchanged I-S samples can be interpreted by random interstratification of several types of sub-units such as layer-doublets, layer-triplets and layer-quarutets present in the crystallites. This interpretation is consistent with the variation in the occurrence probabilities of layer-multiplets calculated from the junction probabilities and the proportions of layers. Because the interpretation indicates that I-S is a stack of various types of the sub-units, the smectite illitization can be described by a systematic change in the type and proportion of the sub-units constituting crystallites
Schaapjes en grassprietjes tellen
Samenwerking tussen Zeeuwse waterschappen en de Animal Sciences Group Wageningen inzake het grasbeheer op dijken
Why NIPT should be publicly funded
Asking pregnant women to (co)pay for non-invasive prenatal testing (NIPT) out of pocket leads to unequal access across socioeconomic strata. To avoid these social justice issues, first-trimester prenatal screening should be publicly funded in countries such as the Netherlands, with universal coverage healthcare systems that offer all other antenatal care
Roman mystique, mystiques romanesques aux XXe et XXIe siècles
The French novel from the past century is filled with desire aroused by mysticism ; this desire simultaneously stretches the novel’s boundaries. The way this desire is expressed reflects contemporary forms of the search for meaning, literature’s way of looking at its own powers and its confrontation with the limits of languag
Directional detection of meV dark photons with Dandelion
This paper presents Dandelion, a new dish antenna experiment searching for
dark photons (DPs) with masses around the meV that will start acquiring data by
the end of 2023. A spherical mirror acts as a conversion surface between DPs
and standard photons that converge to a matrix of 418 Kinetic Inductance
Detectors cooled down to 150 mK. A tilt of the mirror at 1 Hz moves the
expected signal over the pixels thus enabling a continuous background
measurement. The expected signal has two modulations: a spatial modulation
providing a directional signature for the unambiguous discovery of a DP, and an
intensity modulation allowing the determination of the polarization of the DP.
For masses near the meV, the inflationary production of longitudinal and
transverse DPs are mutually excluded, thus the polarization determination by
Dandelion could shed a new light on the inflation phase of the early universe.
A first Dandelion prototype operating for 30 days would improve by more than
one order of magnitude the current exclusion limits on DPs at the meV mass
scale and would probe this region with an unprecedented discovery potential
based on directional detection.Comment: 17 pages, 7 figure
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