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The main objective of this report is to present the dating process routinely applied to different types of samples at the Laboratoire de Mesure du Carbone 14 (LMC14). All the results and protocols refer to our procedures over the last 5 years. A description of the sorting and chemical pretreatments of the samples as well as the extraction and graphitization of CO2 are reported. Our last study concerning the degradation of the blank level according to the storage time of the targets between graphitization and accelerator mass spectrometry (AMS) measurement is also presented. This article also provides information on how to submit a valid laboratory sample. We give details relating to sampling procedures on site as well as contamination issues relative to the 14C dating methodology.
Experiments on the National Ignition Facility show that multi-dimensional effects currently dominate the implosion performance. Low mode implosion symmetry and hydrodynamic instabilities seeded by capsule mounting features appear to be two key limiting factors for implosion performance. One reason these factors have a large impact on the performance of inertial confinement fusion implosions is the high convergence required to achieve high fusion gains. To tackle these problems, a predictable implosion platform is needed meaning experiments must trade-off high gain for performance. LANL has adopted three main approaches to develop a one-dimensional (1D) implosion platform where 1D means measured yield over the 1D clean calculation. A high adiabat, low convergence platform is being developed using beryllium capsules enabling larger case-to-capsule ratios to improve symmetry. The second approach is liquid fuel layers using wetted foam targets. With liquid fuel layers, the implosion convergence can be controlled via the initial vapor pressure set by the target fielding temperature. The last method is double shell targets. For double shells, the smaller inner shell houses the DT fuel and the convergence of this cavity is relatively small compared to hot spot ignition. However, double shell targets have a different set of trade-off versus advantages. Details for each of these approaches are described.
The new facility Artemis was installed in 2003 in Saclay, France. This 3MV NEC Pelletron is dedicated to high-precision radiocarbon measurements for French 14C laboratories. We will present information on Artemis along with our sample preparation methods. Results from measurements on some intercalibration samples will be given along with the values of measured blanks. Finally, we report on some problems we have encountered when measuring sputter cathodes with high CH− outputs.
The Artemis accelerator mass spectrometry (AMS) facility is dedicated to high-precision radiocarbon measurements. It routinely measures over 4500 samples a year for French laboratories. This paper is a status report, showing the measurements of standard, blank, and FIRI intercomparison samples. Since 2008, research and development programs have been established by the Artemis team. During the collaborations with other research laboratories, intercomparisons on archaeological samples were performed and are listed here to show the quality of the Artemis measurements. Three areas of specific research and development are investigated: technical development, beam optic simulations, and specific archaeological studies. The technical developments of the facility are based on the setup of a new bench for water sample preparation and routine microsample preparation and measurement. Beam optic simulations are carried out to control the quality of the measurement related to the tuning of the facility. International collaborations are always in progress. In 2012, the programs include improving the accuracy of reigns for the dynastic Egypt period and the 14C dating of ancient iron.
We present here the new line installed at the LMC14 laboratory (Saclay, France) for dissolved inorganic carbon (DIC) extraction from marine and freshwater samples. The operating system and extraction process are described. The efficiency of the line design was checked, and the background (0.42 ± 0.11 pMC) and the reproducibility on artificial samples obtained by dissolution of IAEA-C1, IAEA-C2, and commercial bicarbonate in water were evaluated. An intercomparison with an independent lab (IDES) was also carried out on a natural sample. The line processes 3 samples a day under a helium flow and is able to run samples up to 40,000 ka.
The Artemis accelerator mass spectrometry (AMS) facility, installed in 2003 in Saclay, France, is devoted to radiocarbon measurements. Samples are submitted by scientists in the fields of Quaternary geology, environmental sciences, and archaeology. The entire preparation process, originally optimized for samples with about 1 mg of carbon, has been tested in recent years for samples with a lower carbon content. In particular, we prepared and measured carbonate and organic background and reference samples ranging in mass from 0.01 to 1 mg C. These tests helped define our protocol's practical limits and determine necessary improvements. Furthermore, our experiments demonstrated that satisfactory graphitization yields (80% and higher) and low background values can be obtained with samples down to 0.2 mg of carbon. For handling smaller samples, we developed a specific process. We tested smaller reactors (5 mL in volume) and adapted the reduction parameters (H2 pressure and temperature) accordingly. We also tested the effect of a chemical water trap on graphitization yields and 14C results. This paper presents in detail the aforementioned developments and reports the 14C results obtained for background and standard small samples prepared with the modified reactors.
Background and aims: For patients with a severe brain injury there is no objective physiotherapy assessment tool that is responsive to the incremental changes in motor recovery in the acute stage. The aims of this study were to identify the items of neuro-motor recovery and scoring criteria for the Acute Brain Injury Physiotherapy Assessment (ABIPA) and determine responsiveness to change and concurrent validity against accepted standard measures of consciousness and physical function in the severe brain injury population.
Method: The literature was searched and an expert consensus panel of experienced clinical physiotherapists informed item selection and developed practical assessment guidelines. The ABIPA was investigated for responsiveness to change and concurrent validity against the Glasgow Coma Scale (GCS), Clinical Outcome Variable Scale (COVS) and Motor Assessment Scale (MAS). Eleven patients (9 males; cohort 41 ± 18 years) with moderate/severe brain injury were recruited, and assessed on days 1, 3, 7 and then weekly until discharge.
Results: The ABIPA demonstrated good to excellent correlations overall with the GCS (rho > .76, p ≤ .001), COVS (rho > .82, p ≤ .001) and MAS (rho > 0.66, p ≤ .001). On day 3, the ABIPA showed the greatest responsiveness to change (standardised response means (SRM) > .83) compared to other measures (SRMs < .77). At discharge all tools demonstrated change in neuro-motor recovery.
Conclusions: The ABIPA is a promising tool for detecting incremental changes in neuro-motor recovery early after severe brain injury.
Imidazoles present a tunable, versatile and economical platform for the development of novel liquid solvents and polymer membranes for CO2 capture. An overview of our studies in this area is presented, with emphasis on characterization of structure-property relationships in imidazole-based materials through both experimental and computational studies. To this end, a growing library of systematically varied imidazole compounds has been synthesized using only commercial available starting materials and straightforward reactions. Using this library of compounds, we have sought to understand and develop predictive models for thermophysical properties relating to process design, including: density, viscosity, vapor pressure, pKa and CO2 absorption capacity. Furthermore, we have discovered that imidazoles are stable in the presence of SO2 and can form reversible 1:1 adducts, which can be beneficial as SO2 is typically present at ppm levels alongside CO2 in flue gas from coal-fired power plants.
Knowledge of the relationship between depressive symptoms and cognition in older adults has primarily come from studies of clinically depressed, functionally impaired or cognitively impaired individuals, and in predominately White samples. Limited minority representation in depression research exposes the need to examine these associations in more ethnic/racially diverse populations. We sought to examine the relationship between depressive symptoms and cognition in a sample of non-demented older African Americans recruited from surrounding U.S. cities of New York, Greensboro, Miami, and Nashville (N=944). Depressive symptoms were evaluated with the Geriatric Depression Scale (GDS). Cognition was evaluated with a comprehensive neuropsychological battery. Test scores were summarized into attention, executive function, memory, language, and processing speed composites. Controlling for age, education, reading level, and sex, African American older adults who endorsed more symptoms obtained significantly lower scores on measures of memory, language, processing speed, and executive functioning. Further investigation of the causal pathway underlying this association, as well as potential mediators of the relationship between depressive symptoms and cognitive test performance among older African Americans, such as cardiovascular and cerebrovascular disease, may offer potential avenues for intervention. (JINS, 2014, 20, 1–8)
We are developing a purely commensal survey experiment for fast (<5 s) transient radio sources. Short-timescale transients are associated with the most energetic and brightest single events in the Universe. Our objective is to cover the enormous volume of transients parameter space made available by ASKAP, with an unprecedented combination of sensitivity and field of view. Fast timescale transients open new vistas on the physics of high brightness temperature emission, extreme states of matter and the physics of strong gravitational fields. In addition, the detection of extragalactic objects affords us an entirely new and extremely sensitive probe on the huge reservoir of baryons present in the IGM. We outline here our approach to the considerable challenge involved in detecting fast transients, particularly the development of hardware fast enough to dedisperse and search the ASKAP data stream at or near real-time rates. Through CRAFT, ASKAP will provide the testbed of many of the key technologies and survey modes proposed for high time resolution science with the SKA.
We measured the spatial and temporal properties of GABAergic and glycinergic inhibition to amacrine cells in the whole-mount rabbit retina. The amacrine cells were parsed into two morphological classes: narrow-field cells with processes spreading less than 200 μm and wide-field cells with processes extending more than 300 μm. The inhibition was also parsed into two types: sustained glycine and transient GABA. Narrow-field amacrine cells receive 1) very transient GABAergic inhibition with a fast onset latency of 140 ± 16 ms decaying to 30% of the peak level within 208 ± 27 ms elicited broadly over a lateral distance of up to 1500 μm and 2) sustained glycinergic inhibition with a medium onset latency of 286 ± 23 ms that was elicited over a spatial area often broader than the processes of the narrow-field amacrine cells. Wide-field amacrine cells received sustained glycinergic inhibition but no broad transient GABAergic inhibition. Surprisingly, neither of these amacrine cell classes received sustained local GABAergic inhibition, commonly found in an earlier study of ganglion cells.
Thermophotovoltaic generation of electricity is attracting renewed attention due to recent advances in low bandgap (0.5–0.7 eV) III-V semiconductors. The use of mixed pseudo-binary compounds allows for the tailoring of the lattice parameter and the bandgap of the material. Conventional deposition techniques (i.e., epitaxy) for producing such ternary or quaternary materials are typically slow and expensive. Production of bulk single crystals of ternary materials, for example Gal-xlnxSb, is expected to dramatically reduce such material costs. Bulk single crystals of Ga1−xInxSb have been prepared using a Bridgman technique in a two-zone furnace. These crystals are 19 mm in diameter by approximately 50 mm long and were produced using seeds of the same diameter. The effects of growth rate and starting materials on the composition and quality of these crystals will be discussed and compared with other attempts to produce single crystals of this material.
We demonstrate, both experimentally and by computer simulation, that while the metastable face-centered cubic (fcc) phase of Ge-Sb-Te becomes amorphous under hydrostatic compression at about 15 GPa, the stable trigonal phase remains crystalline. We present evidences that the pressure-induced amorphisation phenomenon strongly depends on the concentration of vacancies included in the Ge/Sb sublattice, but is thermally insensitive. Upon higher compression, a body-centered cubic phase is obtained in both cases at around 30 GPa. Upon decompression, the amorphous phase is retained when starting with the fcc phase while the initial structure is recovered when starting with the trigonal phase. We argue that the presence of vacancies and the associated subsequent large atomic displacements lead to nanoscale phase separation and the loss of the initial structure memory in the fcc staring phase of Ge-Sb-Te. We futher compare the amorphous phase obtained via the pressure route with the melt quenched amorphous phase.
We sought to determine and compare rates of pediatric mental health presentations and associated costs in emergency departments (EDs) in Alberta.
We examined 16 154 presentations by 12 589 patients (patient age ≤ 17 yr) between April 2002 and March 2006 using the Ambulatory Care Classification System, a province-wide database for Alberta. The following variables of interest were extracted: patient demographics, discharge diagnoses, triage level, disposition, recorded costs for ED care, and institutional classification and location (i.e., rural v. urban, pediatric v. general EDs).
A 15% increase in pediatric mental health presentations was observed during the study period. Youth aged 13-17 years consistently represented the most common age group for first presentation to the ED (83.3%). Of the 16 154 recorded presentations, 21.4% were related to mood disorders and 32.5% to anxiety disorders. Presentations for substance misuse or abuse were the most prevalent reasons for a mental health-related visit (41.3%). Multiple visits accounted for more than one-third of all presentations. Presentations for mood disorders were more common in patients with multiple compared with single visits (29.3% v. 16.9%), and substance abuse or misuse presentations were more common in patients with single compared with multiple visits (47.4% v. 30.5%). The total direct ED costs for mental health presentations during the study period was Can$3.5 million.
This study provides comprehensive data on trends of pediatric mental health presentation, and highlights the costs and return presentations in this population. Psychiatric and medical care provided in the ED for pediatric mental health emergencies should be evaluated to determine quality of care and its relationship with return visits and costs.
A study of the ideal magnetohydrodynamic linear eigenvalue spectrum for free-boundary modes in the Z-pinch is presented. The application of a variational method to estimate eigenvalues is described and limitations imposed by the nature of the spectrum are discussed. An analytic expression for the long-wavelength m = 0 growth rate is derived
Vertically transmitted parasites may have positive, neutral or negative effects on host fitness, and are also predicted to exhibit sex-specific virulence to increase the proportion or fitness of the transmitting sex. We investigated these predictions in a study on the survival and sex ratio of offspring of the amphipod Gammarus roeseli from females infected by the vertically transmitted microsporidia Nosema granulosis. We found, to our knowledge, the first evidence for a positive relationship between N. granulosis infection and host survival. Infection was associated with sex ratio distortion, not by male-killing, but probably by parasite-induced feminization of putative G. roeseli males. This microsporidia also feminizes another amphipod host, Gammarus duebeni, which is phylogenetically and biogeographically distant from G. roeseli. Our study suggests that the reproductive system of gammarids is easily exploited by these vertically-transmitted parasites, although the effects of infections on host fitness may depend on specific host-parasite species interactions.
Background: Studies indicate that diet may be related to the occurrence of brain lesions. The cross-sectional association between food intake and brain lesion volumes in late-life depression was examined in a cohort of elderly individuals with current or prior depression.
Methods: Food intake was assessed in 54 elderly vascular depression subjects (vascular depression defined by presence of hyperintensities on brain MRI) using a Block 1998 food frequency questionnaire. Food and kilocalorie intake were determined. Brain lesion volumes were calculated from MRI. Subjects were aged 60 or over and were participants in a longitudinal study of major depression. All subjects received psychiatric assessment and treatment, and medical comorbidity assessments.
Results: High-fat dairy and whole grains were significantly positively correlated with brain lesion volume, while other food groups were not significantly associated with lesion volume. In multivariable analyses, controlling for age, sex, hypertension, diabetes and total kilocalories, the positive association with lesion volume remained significant for both high-fat dairy and whole grains.
Conclusions: High fat dairy and whole grain consumption may be associated with brain lesions in elderly subjects with depression.
To assess the impact of particulate emissions from Port Talbot Works on local air
quality, a detailed mathematical analysis of ambient
particulate data collected in the
borough over several years has been completed, with a special focus on the period
following the stoppage of
n° 5 Blast Furnace in 2001. This work was done following
the declaration of an Air Quality Management Area (AQMA) adjacent to Port
Talbot Works, in order to tackle the high incidence of exceedances of the
24 h PM10 objective in this area.