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This research investigates two factors influencing the ability of tree-ring data to provide accurate 14C calibration information: the fitness and rigor of the statistical model used to combine the data into a curve; and the accuracy, precision and reproducibility of the component 14C data sets. It presents a new Bayesian spline method for calibration curve construction and tests it on extant and new Southern Hemisphere (SH) data sets (also examining their dendrochronology and pretreatment) for the post-Little Ice Age (LIA) interval AD 1500–1950. The new method of construction allows calculation of component data offsets, permitting identification of laboratory and geographic biases. Application of the new method to the 10 suitable SH 14C data sets suggests that individual offset ranges for component data sets appear to be in the region of ± 10 yr. Data sets with individual offsets larger than this need to be carefully assessed before selection for calibration purposes. We identify a potential geographical offset associated with the Southern Ocean (high latitude) Campbell Island data. We test the new methodology for wiggle-matching short tree-ring sequences and use an OxCal simulation to assess the likely precision obtainable by wiggle-matching in the post-LIA interval.
Breastfeeding may reduce obesity risk, but this association could be confounded by breastfeeding families’ characteristics. We investigated if body composition differs at birth among infants who were either exclusively breast- or formula-fed. We hypothesized the two groups would differ in body composition, even at birth, prior to their post-natal feeding experience. Healthy primiparous carrying singleton pregnancy were recruited at 15 weeks’ gestation. PEA POD® measured body composition within 72 hours of delivery and infant feeding was prospectively captured. Out of the 1,152 infants recruited, 117 (10.2%) and 239 (20.7%) went on to be either exclusively breast- or formula-fed, respectively. Breastfed infants were heavier at birth, but their percentage fat mass (FM) was lower than that of exclusively formula-fed infants (covariate adjusted β = −1.91 percentage points of FM; 95% CI −2.82 to −1.01). Differences in intra-uterine exposures, irrespective of early diet, may partly explain an infant’s obesity risk.
The novel Volumetric Image Matching Environment for Radiotherapy (VIMER) was
developed to allow users to view both computed tomography (CT) and cone-beam
CT (CBCT) datasets within the same 3D model in virtual reality (VR) space.
Stereoscopic visualisation of both datasets combined with custom slicing
tools and complete freedom in motion enables alternative inspection and
matching of the datasets for image-guided radiotherapy (IGRT).
Material and methods:
A qualitative study was conducted to explore the challenges and benefits of
VIMER with respect to image registration. Following training and use of the
software, an interview session was conducted with a sample group of six
university staff members with clinical experience in image matching.
User discomfort and frustration stemmed from unfamiliarity with the
drastically different input tools and matching interface. As the primary
advantage, the users reported match inspection efficiency when presented
with the 3D volumetric renderings of the planning and secondary CBCT
This study provided initial evidence for the achievable benefits and
limitations to consider when implementing a 3D voxel-based dataset
comparison VR tool including a need for extensive training and the minimal
interruption to IGRT workflow. Key advantages include efficient 3D
anatomical interpretation and the capability for volumetric matching.
The rapid, quantitative and qualitative analysis of particulates on air filter samples is becoming increasingly important as more air pollution sampling stations are set up throughout the countiy. Although atomic absorption provides a sensitive technique for the analysis of many elements, the disadvantages of complex sample preparation, sample destruction and the necessity to analyze one element at a time make this technique unsuitable for a large volume of samples. X-ray energy spectroscopy when combined with automated sample handling and the latest dedicated data reduction systems provides a technique which enables the analyst to process large numbers of samples and obtain precise quantitative and qualitative data rapidly. This paper will describe the preparation and analysis of typical air filter type samples, and the steps taken to identify the elements in the samples and obtain computerized reduction of the data in μg/cm2, ppm or percent.
Current developments in the recently introduced method of HgI2 crystal platelet growth by polymer assisted vapor transport are described. Crystal parameters are evaluated by making electrical measurements on x-ray detectors fabricated from HgI2 platelets, Selection for detector fabrication is on the basis of size and apparent crystalline perfection. Detectors have been fabricated with active areas averaging 2 to 3 mm2 and thicknesses ranging from 20 to 400 µm. Values of electron mobility and mobility-lifetime product measured for HgI2 platelet material are among the highest ever observed for HgI2.
The combination of low leakage current and good electron transport makes HgI2 platelets suitable for room-temperature x-ray spectrometry. An energy resolution of 370 eV (FWHM) for the 5.9 KeV Mn Kα line has been obtained, and representative low-energy x-ray fluorescence spectra are presented.
Once on a plane to New Orleans I chanced to half overhear a conversation between two passengers who shared the same row of seats with me. Somewhere between wakefulness and drowsiness, my ear caught a telltale accent that betrayed one of my seatmates as an Orleanian as they chatted animatedly about the Crescent City, Louisiana, and the ways that both diverged from the rest of the country. The native noted reverently the influence of the Roman Catholic Church, he remarked grandly on the extraordinary cuisine, he waxed pridefully about the city as the birthplace of jazz, and he spoke warmly about the manifold ethnic origins of his fellow Louisianians. Then, as if to fortify his contention that he hailed from a truly unusual place, he pointedly observed that Louisiana was the only state in the nation whose legal system rested upon the Napoleonic Code, even as he confessed to an uncertainty about why that difference existed or what it meant precisely.
We compared sepsis “time zero” and Centers for Medicare and Medicaid Services (CMS) SEP-1 pass rates among 3 abstractors in 3 hospitals. Abstractors agreed on time zero in 29 of 80 (36%) cases. Perceived pass rates ranged from 9 of 80 cases (11%) to 19 of 80 cases (23%). Variability in time zero and perceived pass rates limits the utility of SEP-1 for measuring quality.
Although generally considered rare in gastropods, septation has long been noted in turritellids, but functional hypotheses do not survive strong scrutiny. Here we outline a methodology for testing spandrel hypotheses and apply it to the problem of turritellid septa. We follow Gould in using “spandrel” as a term for all features that are nonadaptive sequelae of adaptive features of organisms, including those that are structurally necessary, those that are developmentally correlated, and nondeterministic by-products that are correlated to features under selection.
In turritellids, septa are constructed in microstructural continuity with secondary internal thickening of the shell, are highly variable features infraspecifically, and are strongly associated with degree of shell thickening. We therefore conclude that rather than being themselves adaptive, turritellid septa are spandrels of shell thickening. Turritellid septa are composed of crossed lamellar aragonite, which appears to be constructed by mantle epithelium over the visceral mass. Septation was also found in 22 of 24 gastropod families examined from a broad phylogenetic distribution. Septa thus appear to be a widespread feature of caenogastropods, in strong contrast to previous assertions that septa are less common in modern or high-spired shells.
Mentorship is perceived to be an important component of residency education. However, evidence of the impact of mentorship on professional development in Emergency Medicine (EM) is lacking.
Online survey distributed to attending physician members of the Canadian Association of Emergency Physicians (CAEP), using a modified Dillman method. Survey contained questions about mentorship during residency training, and perceptions of the impact of mentorship on career development.
The response rate was 23.5% (309/1314). 63.6% reported having at least one mentor during residency. The proportion of participants with a formal mentorship component during residency was higher among those with mentors (44.5%) compared to those without any formal mentorship component during residency (8.0%, p<0.001). The most common topics discussed with mentors were career planning and work-life balance. The least common topics included research and finances. While many participants consulted their mentor regarding their first job (56.5%), fewer consulted their mentor regarding subspecialty training (45.1%) and research (41.1%). 71.8% chose to work in a similar centre as their mentor, but few completed the same subspecialty (24.8%), or performed similar research (30.4%). 94.1% stated that mentorship was important to success during residency. Participants in a formal mentorship program did not rate their experience of mentorship higher than those without a formal program.
Among academic EM physicians with an interest in mentorship, mentorship during EM residency may have a greater association with location of practice than academic scholarship or subspecialty choice. Formal mentorship programs increase the likelihood of obtaining a mentor, but do not appear to improve reported mentorship experiences.
The changes in the payment scheme proposed by the Milk Marketing Board from 1 April 1984 cover a number of issues relating to compositional quality, seasonality of pricing and the monthly distribution of production. Although the changes in total must be financially self-balancing on a national basis, the effect on individual farms may be significant.
A computer program has been used on the records from a number of farms to investigate the effect of the changes, separately and together, on annual and monthly income from milk. The effects on three herds were as follows.
Herd 1 was a Jersey herd that showed an overall increase in income per cow, due mainly to the higher price of protein. Herds with a high protein to lactose ratio in the milk will stand to gain from the new price of protein.
Herd 2 was a Friesian/Holstein herd with a low protein and low milk fat content in the milk. The herd was also calving seasonally and had a low output of milk during August and September. A substantial decrease in income of approximately £29 per cow was due principally to the low protein to lactose ratio but also to the low fat content and the seasonal pattern of milk production on the farm.
Farm management is the meeting-point of science, economics, man-management, marketing, planning and decision-making on the farm. From such a diverse background and because of the variable nature of farming itself, the supply of management information to the farmer is a subject which merits considerable attention.
To identify the importance of management, it is worth considering the range in performance between farms, as measured by dairy herd gross margin per hectare. The average for 1979/80 of Farm Management Services (FMS) fully costed herds (MMB, 1980) was £546/ha, while the result for the ‘top 25%” was £809/ha, a difference of £263/ha. It is exceedingly difficult to define precisely the part which management plays in this difference. However, through its effect on feeding, breeding, grassland management, fertility and health, it is probably the dominant factor. If the range in FMS results were to be taken as the normal distribution for the national herd, one could postulate that bringing up the national average gross margin to that of the “top 25%” would add a further £127m to the national dairy herd gross margin. This would be equivalent to slightly in excess of £4 000 in the average 60 cow herd. Whilst admitting that not every farmer nor every farm can achieve the level of performance of the “top 25%”, such calculations do indicate the extent over which management has an influence.
Ruminant products are considered as a major source of saturated fatty acids (SFA) in the human diet and a reduction in the intake of SFA along with a concomitant increase in the intake of n-3 series PUFA is recommended by nutritionists (Department of Health, 1994). The major fatty acid classes in beef are the saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) and beef is a nutritionally important source of the beneficial n-3 series PUFA. Experiments investigating the effects of age on lipid composition in beef muscle have, in the main, used short time periods and also been subject to confounding effects of differences in growth rate (Rule et al., 1997). This study is part of a larger investigation into the effects of breed and diet, as well as age, on muscle lipids (Warren et al., 2003). This paper will focus on the effect of age.
Some studies with beef cattle have shown that breed and diet affect tissue fatty acid composition and meat quality (Choi et al., 2000; Scollan et al., 2001). However, the effects of breed are often confounded with differences in growth rate and body composition. Diet also affects fatty acid composition, however, feed composition studies are often confounded by the use of mixed diets and few have compared all-forage with all-concentrate diets. This study, therefore, was designed to compare Aberdeen Angus and Holstein-Friesian breeds growing at similar rates and fed either all-forage or a high concentrate diet.
Data relating to calving dynamics in fresh water are scarce, especially for deep-water sites. A linear dependence of calving velocity (Vc) on water depth (Hw) is commonly accepted for both tidewater and fresh-water calving glaciers. Here we use recent data from temperate Patagonian glaciers to propose a revised relationship for calving in fresh water. The new ratio is derived from glaciers calving rapidly into deep water, documented using sequential satellite images and depth soundings. The main data source is a detailed remotely sensed dataset of the rapidly retreating Glaciar Upsala, complemented with global positioning system field surveys and precise ice-proximal bathymetric surveys. The area-integrated mean water depth between glacier positions in 1996 and 2000 is 490 m, with a maximum recorded depth of >700m. In the same period, image analysis reveals surface area loss of 1.37 km2 a–1 (4.8 km2) and an average calving rate of 1880ma–1. The resulting Vc/Hw ratio is of a similar order of magnitude to that recently derived for nearby Glaciar Moreno, but is well above the range of values commonly reported for lacustrine calving.
Chemical constituents trapped within glacial ice provide a unique record of climate, as well as repositories for biological material such as pollen grains, fungal spores, viruses, bacteria and dissolved organic carbon. Past research suggests that the veins of polycrystalline ice may provide a liquid microenvironment for active microbial metabolism fueled by concentrated impurities in the veins. Despite these claims, no direct measurements of impurity concentration in ice veins have been made. Using micro-Raman spectroscopy, we show that sulfate and nitrate concentrations in the veins of glacial ice from Greenland (Greenland Ice Sheet Project 2) and Antarctic (Newall Glacier and a Dominion Range glacier) core samples were 104 and 105 times greater than the concentrations measured in melted (bulk) core water. Methanesulfonate was not found in the veins, consistent with its presence as particulate matter within the ice. The measured vein concentration of molecular anions implies a highly acidic (pH < 3) vein environment with high ionic strength (mM-M). We estimate that the vein volume provides 16.7 and 576 km3 of habitable space within the Greenland and Antarctic ice sheets, respectively, which could support the metabolism of organisms that are capable of growing in cold, high ionic strength solutions with low pH.
The northern New England region includes the states of Vermont, New Hampshire, and Maine and encompasses a large degree of climate and edaphic variation across a relatively small spatial area, making it ideal for studying climate change impacts on agricultural weed communities. We sampled weed seedbanks and measured soil physical and chemical characteristics on 77 organic farms across the region and analyzed the relationships between weed community parameters and select geographic, climatic, and edaphic variables using multivariate procedures. Temperature-related variables (latitude, longitude, mean maximum and minimum temperature) were the strongest and most consistent correlates with weed seedbank composition. Edaphic variables were, for the most part, relatively weaker and inconsistent correlates with weed seedbanks. Our analyses also indicate that a number of agriculturally important weed species are associated with specific U.S. Department of Agriculture plant hardiness zones, implying that future changes in climate factors that result in geographic shifts in these zones will likely be accompanied by changes in the composition of weed communities and therefore new management challenges for farmers.
Deep CCD imaging of the Serpens bipolar nebula shows it to be surrounded by molecular cloud material having spiral density structure. Polarization mapping indicates that the magnetic field in this material also exhibits spiral structure and we interpret this as the remains of the magnetically-braked collapse of a protostellar cloud. A binary star system has formed in the cloud core.