9,379 research outputs found

    The relationship between dental status, food selection, nutrient intake, nutritional status, and body mass index in older people

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    This paper reviewed the findings from a national survey in Great Britain which assessed whether dental status affected older people's food selection, nutrient intake, and nutritional status. The survey analyzed national random samples of free-living and institution subjects for dental examination, interview, and four-day food diary as well as blood and urine tests In the free-living sample, intakes of non-starch polysaccharides, protein, calcium, non-heme iron, niacin, and vitamin C were significantly lower in edentulous as compared to dentate subjects. People with 21 or more teeth consumed more of most nutrients, particularly non-starch polysaccharides. This relationship in intake was not apparent in the hematological analysis. Plasma ascorbate and retinol were the only analytes significantly associated with dental status. Having 21 or more teeth increased the likelihood of having an acceptable body mass index (BMI). Thus, maintaining a natural and functional dentition defined as having more than twenty teeth into old age plays an important role in having a healthy diet rich in fruits and vegetables, a satisfactory nutritional status, and an acceptable BMI

    Close-packed structures and phase diagram of soft spheres in cylindrical pores

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    It is shown for a model system consisting of spherical particles confined in cylindrical pores that the first ten close-packed phases are in one-to-one correspondence with the first ten ways of folding a triangular lattice, each being characterized by a roll-up vector like the single-walled carbon nanotube. Phase diagrams in pressure-diameter and temperature-diameter planes are obtained by inherent-structure calculation and molecular dynamics simulation. The phase boundaries dividing two adjacent phases are infinitely sharp in the low-temperature limit but are blurred as temperature is increased. Existence of such phase boundaries explains rich, diameter-sensitive phase behavior unique for cylindrically confined systems

    Extended Water Quality Monitoring of the Lincoln Lake Watershed

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    For seven years, the Lincoln Lake (Moores Creek and Beatty Branch) watershed was monitored for improvements in water quality resulting from agricultural best management practices (BMP) implemented to reduce nutrient transport. During the first three years of monitoring (1991 to 1994), nitrogen transport declined significantly (Edwards et al., 1994, 1996, and 1997) under both base and storm flow conditions. This decline in nitrogen transport was again observed in the three-year period following 1994 (Vendrell et al. 1998). This monitoring effort has demonstrated that water quality bas improved in the Lincoln Lake watershed. However, since the nitrogen transport continued to decline and there was some indication that phosphorus may begin to decline, monitoring was extended for another year (1998)

    Effective potentials and electrostatic interactions in self-assembled molecular bilayers II: the case of biological membranes

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    We propose a very simple but realistic enough model which allows to include a large number of molecules in molecular dynamics MD simulations of these bilayers, but nevertheless taking into account molecular charge distributions, flexible amphiphilic molecules and a reliable model of water. All these parameters are essential in a nanoscopic scale study of intermolecular and long range electrostatic interactions. This model was previously used by us to simulate a Newton black film and in this paper we extend our investigation to bilayers of the biological membrane type. The electrostatic interactions are calculated using Ewald sums and, for the macroscopic long range electrostatic interactions, we use our previously proposed coarsed fit of the (perpendicular to the bilayer plane) molecular charge distributions with gaussian distributions. To study an unique biological membrane (not an stack of bilayers), we propose a simple effective external potential that takes into account the microscopic pair distribution functions of water and is used to simulate the interaction with the surrounding water. The method of effective macroscopic and external potentials is extremely simple to implement in numerical simulations, and the spatial and temporal charge inhomogeneities are then roughly taken into account. Molecular dynamics simulations of several models of a single biological membrane, of neutral or charged polar amphiphilics, with or without water (using the TIP5P intermolecular potential for water) are included

    A split-cavity design for the incorporation of a DC bias in a 3D microwave cavity

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    We report on a technique for applying a DC bias in a 3D microwave cavity. We achieve this by isolating the two halves of the cavity with a dielectric and directly using them as DC electrodes. As a proof of concept, we embed a variable capacitance diode in the cavity and tune the resonant frequency with a DC voltage, demonstrating the incorporation of a DC bias into the 3D cavity with no measurable change in its quality factor at room temperature. We also characterize the architecture at millikelvin temperatures and show that the split cavity design maintains a quality factor Qi8.8×105Q_\text{i} \sim 8.8 \times 10^5, making it promising for future quantum applications

    Imaging Transport Resonances in the Quantum Hall Effect

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    We use a scanning capacitance probe to image transport in the quantum Hall system. Applying a DC bias voltage to the tip induces a ring-shaped incompressible strip (IS) in the 2D electron system (2DES) that moves with the tip. At certain tip positions, short-range disorder in the 2DES creates a quantum dot island in the IS. These islands enable resonant tunneling across the IS, enhancing its conductance by more than four orders of magnitude. The images provide a quantitative measure of disorder and suggest resonant tunneling as the primary mechanism for transport across ISs.Comment: 4 pages, 4 figures, submitted to PRL. For movies and additional infomation, see http://electron.mit.edu/scanning/; Added scale bars to images, revised discussion of figure 3, other minor change

    Adsorption of Xe and Ar on Quasicrystalline Al-Ni-Co

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    An interaction potential energy between and adsorbate (Xe and Ar) and the 10-fold Al-Ni-Co quasicrystal is computed by summing over all adsorbate-substrate interatomic interactions. The quasicrystal atoms' coordinates are obtained from LEED experiments and the Lennard-Jones parameters of Xe-Al, Xe-Ni and Xe-Co are found using semiempirical combining rules. The resulting potential energy function of position is highly corrugated. Monolayer adsorption of Xe and Ar on the quasicrystal surface is investigated in two cases: 1) in the limit of low coverage (Henry's law regime), and 2) at somewhat larger coverage, when interactions between adatoms are considered through the second virial coefficient, C_{AAS}. A comparison with adsorption on a flat surface indicates that the corrugation enhances the effect on Xe-Xe (Ar-Ar) interactions. The theoretical results for the low coverage adsorption regime are compared to experimental (LEED isobar) data.Comment: 12 pages, 8figure

    Bacterial meningitis in older neonates

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    During a five-year period, 24 patients' conditions (age range, 2 to 6 weeks) were diagnosed, and they were treated for bacterial meningitis. Organisms recovered from the CSF included group B Streptococcus (n = 6), Escherichia coli (n = 5), Listeria monocytogenes (n = 5), Hemophilus influenzae (n = 4), Streptococcus pneumoniae (n = 2), and group D and group A Streptococcus (one each). Initial antimicrobial therapy must include antibiotics that are effective across this spectrum of potential pathogens. Symptoms and signs were often subtle. Six children (25%) experienced major neurologic residua, including five patients (21%) in whom hydrocephalus developed. Ultrasound examination of the head at the end of therapy was an effective technique for early assessment of neurologic sequelae
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