Variety Of Physical Measurements Research Articles

Defining periodontal health.

Assessment of the periodontium has relied exclusively on a variety of physical measurements (e.g., attachment level, probing depth, bone loss, mobility, recession, degree of inflammation, etc.) in relation to various case definitions of periodontal disease. Periodontal health was often an afterthought and was simply defined as the absence of the signs and symptoms of a periodontal disease. Accordingly, these strict and sometimes disparate definitions of periodontal disease have resulted in an idealistic requirement of a pristine periodontium for periodontal health, which makes us all diseased in one way or another. Furthermore, the consequence of not having a realistic definition of health has resulted in potentially questionable recommendations. The aim of this manuscript was to assess the biological, environmental, sociological, economic, educational and psychological relationships that are germane to constructing a paradigm that defines periodontal health using a modified wellness model. The paradigm includes four cardinal characteristics, i.e., 1) a functional dentition, 2) the painless function of a dentition, 3) the stability of the periodontal attachment apparatus, and 4) the psychological and social well-being of the individual. Finally, strategies and policies that advocate periodontal health were appraised.I'm not sick but I'm not well,and it's a sin to live so well.Flagpole Sitta, Harvey Danger

Acoustic measurements of rock formations in oilfield boreholes

Once a borehole is drilled into a rock formation as a potential oil or gas well the environment needs to be characterized by a variety of physical measurements so that e.g. one may know at what depths the hydrocarbon, if any, is located. In this talk I will outline some techniques for measuring, in situ, the compressional and shear speeds of sound in a rock formation as a function of depth. Here the “difficult and challenging conditions” are that the measuring instrument is inside the sample (rather than the other way around), the temperatures may reach 175 °C, and the pressure in the borehole may reach as high as 1000 atmospheres.

Carbide-Derived Nanoporous Carbon and Novel Core−Shell Nanowires

Carbide-derived carbon (CDC) nanowires (NWs) have been synthesized by the high-temperature treatment of small-diameter β-SiC whiskers with Cl2/H2. A variety of physical measurements indicate that Si was extracted by exposure to Cl2 and that the C in the carbon nanowires is primarily sp2-bonded. From BET measurements, the specific surface area of these carbon nanowires is 1.3 × 103 m2/g and they contain a network of nanopores. Nanoindentation measurements indicate that the SiC-derived C is not a stiff material, the elastic modulus being 5.0 ± 1.2 GPa. High-temperature treatment of the CDC nanowires under an inert gas significantly increases the degree of graphitization. In addition, partial extraction was used to obtain core−shell structures having a thin and also very high surface area CDC shell; further treatment at high temperature was used to produce graphitized carbon shell−crystalline SiC core NWs.

New mesogens with cubic phases: hydrogen-bonded bipyridines and siloxane-containing benzoic acids I. Preparation and phase behaviour

Several 4-(oligodimethylsiloxyl)alkoxybenzoic acids and their hydrogen-bonded complexes with 4,4-dipyridyl or 1,2-bis(4-pyridyl)ethane were prepared and their phase behaviour studied by DSC and polarized optical microscopy. The neat acids showed no liquid crystalline phases. The 4,4-dipyridyl complex of 4-(n-heptamethyltrisiloxyl)hexyloxybenzoic acid (Si3C6BA) exhibits an optically isotropic, highly viscous liquid crystalline phase below a smectic A phase. The 1,2-bis(4-pyridyl)ethane complex of Si3C6BA also shows an optically isotropic liquid crystalline phase above its smectic C phase. Its behaviour is similar to that of the well known cubic D phase found in 4-n-alkoxy-3-nitrobiphenyl-4-carboxylic acids. In the hydrogenbonded mesogens studied herein, the cubic phase appears to assemble spontaneously in order to take account of the chemical incompatibility between the siloxane moiety terminating the H-bonded complex and the stiff aromatic cores. The transition temperatures of the cubic phases in these materials is around 100oC, hence they are amenable to a variety of physical measurements.

Computed tomographic study of lumbar (L3–4) epidural depth and its relationship to physical measurements in young adult men

Background and Objectives. This study was performed to devise a method for predicting epidural depth more accurately with a variety of physical measurements not previously studied. Methods. Computed tomography was used to accurately measure the L3–4 epidural depth. The inclusion criteria were restricted to healthy men, 20–25 years of age, in order to rule out the influences of age and sex. Results. Significant correlations with depth from skin to the center of the “triangular” posterior epidural space (Sk-Ep) were found for waist circumference, waist circumference/height ratio, body mass index (BMI), weight/height ratio, weight/neck circumference ratio, and weight. The depth from the supraspinous ligament to the center of the posterior epidural space (Sl-Ep) did not correlate with any physical measurements. However, Sk-Sl, which equals Sk-Ep minus Sl-Ep (ie, the depth from the skin to the supraspinous ligament) correlated with waist circumference/height ratio, waist circumference, BMI, and weight/height ratio. Conclusion. Addition of the physical parameters such as waist circumference/neck circumference ratio or BMI results in a higher predictive value for epidural depth than use of more traditional physical parameters such as weight/height ratio and/or weight only. The value of Sl-Ep is independent of any physical parameters. Thus, the significant correlation between the physical measurements and the epidural depth seems to be due only to obesity-related factors.

Hydrologic issues in arid, unsaturated systems and implications for contaminant transport

Analysis of unsaturated flow and transport in arid regions is important, not only in water resource evaluation but in contaminant transport as well, particularly in siting waste disposal facilities and in remediating contaminated sites. The water fluxes under consideration have a magnitude close to the errors inherent in measuring or in calculating these water fluxes, which makes it difficult to resolve basic issues such as direction and rate of water movement and controls on unsaturated flow. The purpose of this paper is to review these issues on the basis of unsaturated zone studies in arid settings. Because individual techniques for estimating water fluxes in the unsaturated zone have limitations, a variety of physical measurements and environmental tracers should be used to provide multiple, independent lines of evidence to quantify flow and transport in arid regions. The direction and rate of water flow are affected not only by hydraulic head gradients but also by temperature and air pressure gradients. The similarity of water fluxes in a variety of settings in the southwestern United States indicates that vegetative cover may be one of the primary controls on the magnitude of water flow in the unsaturated zone; however, our understanding of the role of plants is limited. Most unsaturated flow in arid systems is focused beneath topographic depressions, and diffuse flow is limited. Thick unsaturated sections and low water fluxes typical of many arid regions result in preservation of paleoclimatic variations in water flux and suggest that deep vadose zones may be out of equilibrium with current climate. Whereas water movement along preferred pathways is common in humid sites, field studies that demonstrate preferential flow are restricted mostly to fractured rocks and root zones in arid regions. Results of field studies of preferential flow in humid sites, generally restricted to the upper 1–2 m because of shallow water tables, cannot be applied readily to thick vadose zones in arid regions.

Carcass composition of “bob” and “special-fed” veal and its prediction

Percentage of lean, fat, and bone were determined in 18 bob veal (BV) and 28 special-fed veal (SFV) carcasses. Carcasses were subjected to a set of visual conformation scores and a variety of physical measurements. No significant differences were found regarding carcass percentage of lean, fat, and bone within the three BV weight groups (P > .05). On average, SFV were 12% fatter than BV and did not have a greater percentage of lean (P > .05), except for SFV carcasses weighing 88.2 to 97.7 kg. Bob veal had less fat (internal, external, and intermuscular) and a higher bone percentage than SFV (P < .05). The round and shoulder primals had the greatest proportion of lean in both the BV and SFV carcasses. Bob veal carcasses had an average conformation score of average Good and SFV carcasses had an average conformation score of average Choice. In addition, a parsimonious subset of variables was identified for predicting total percentage of lean (TPLEAN) for both BV and SFV separately, using "stepwise" regression model building procedures. For BV, all four identified predictor variables were subjective conformation scores (i.e., muscling, appearance, leg thickness, loin-back plumpness) (R = .73, P < .03). For SFV, four predictor variables were also identified: kidney and pelvic fat, fat thickness, carcass length, and lateral thickness (R = .61, P < .03). Although both regression equations were significant predictors of TPLEAN, confidence limits for predicting future TPLEAN value were wide relative to the variation in the actual TPLEAN values. Thus, the practical utility of the regression equations is limited.

Water interactions with varying molecular states of bovine casein: 2H NMR relaxation studies

The caseins occur in milk as spherical colloidal complexes of protein and salts with an average diameter of 1200 Å, the casein micelles. Removal of Ca 2+ is thought to result in their dissociation into smaller protein complexes stabilized by hydrophobic interactions and called submicelles. Whether these submicelles actually occur within the micelles as discrete particles interconnected by calcium phosphate salt bridges has been the subject of much controversy. A variety of physical measurements have shown that casein micelles contain an inordinately high amount of trapped water (2 to 7 g H 2O/g protein). With this in mind it was of interest to determine if NMR relaxation measurements could detect the presence of this trapped water within the micelles, and to evaluate whether it is a continuum with picosecond correlation times or is associated in part with discrete submicellar structures with nanosecond motions. For this purpose the variations in 2H NMR longitudinal and transverse relaxation rates of water with protein concentration were determined for bovine casein at various temperatures, under both submicellar and micellar conditions. D 2O was used instead of H 2O to eliminate cross-relaxation effects. From the protein concentration dependence of the relaxation rates, the second virial coefficient of the protein was obtained by nonlinear regression analysis. Using either an isotropic tumbling or an intermediate asymmetry model, degrees of hydration, ν , and correlation times, τ c , were calculated for the caseins; from the latter parameter the Stokes radius, r, was obtained. Next, estimates of molecular weights were obtained from r and the partial specific volume. Values were in the range of those published from other methodologies for the submicelles. Temperature dependences of the hydration and Stokes radius of the casein submicelles were consistent with the hypothesis that hydrophobic interactions represent the predominant forces responsible for the aggregation leading to a submicellar structure. The same temperature dependence of r and ν was found for casein under micellar conditions; here, the absolute values of both the Stokes radii and hydrations were significantly greater than those obtained under submicellar conditions, even though τ c values corresponding to the great size of the entire micelle would result in relaxation rates too fast to be observed by these NMR measurements. The existence of a substantial amount of trapped water within the casein micelle is, therefore, corroborated, and the concept that this water is in part associated with submicelles of nanosecond motion is supported by the results of this study.

An Instrument for Continuously Measuring Capacitance Changes

A method of measurement which can be applied to resolve small capacitance changes and yet can respond linearly to large capacitance changes was described by us previously. In the present paper this method is discussed further, and it is shown how it can be used to develop a versatile instrument which finds important applications in variety of physical measurements. The general features of the instrument are considered with suggestions of further improvement.

Gradients of U, Pu and O at surfaces of

Abstract Due to slow metal atom diffusion, non-congruent evaporation of (U, Pu)O 2 ± x may lead to pronounced gradients of U and Pu at the surfaces of preannealed or as-sintered specimens. The Pu content at the surface can easily decrease (for reduced oxides) or increase (for near stoichiometric or oxidized specimens) by a factor of 2. The metal atom gradient thus formed causes an oxygen gradient. Such gradients frequently remain undetected by chemical analysis since normally they only extend to a depth of about 0.1 to 5 μm. Yet, they can drastically affect (and probably have done) quite a variety of physical measurements reported in the literature. The errors involved can easily be larger than an order of magnitude.

New method of continuously measuring differential capacitance changes

A new instrument has been developed which can resolve small capacitance changes and yet can respond to large capacitance changes linearly. Such a versatile instrument has important applications in a variety of physical measurements.

The resolution of some discrepancies concerning the molecular weight and subunit structure of succinate dehydrogenase

Values in the literature for the molecular weight of mammalian succinate dehydrogenase, based on a variety of physical and chemical measurements, range from 100,000 to 200,000 and the enzyme has been generally assumed to exist as a monomer in solution. Recent reports indicate the presence of two subunits of 70,000 and 30,000 molecular weight, which have been assumed (but not proven) to be present in a 1:1 ratio. It has been shown in the present study for two types of soluble preparations that analysis for histidyl flavin indicates a minimum molecular weight of 10 5 ± 5,000, but a variety of physical measurements (chromatography on Agarose and Sephadex, density gradient centrifugation, and sedimentation-diffusion) indicate a molecular weight of 175,000 ± 10,000. The reason for this discrepancy appears to be that the enzyme exists in solution in a dynamic monomer-dimer equilibrium. This interpretation is supported by the concentration dependence of the apparent molecular weight and the broadness of the peaks in gel elution and in density gradient profiles. The subunit molecular weights have been confirmed but the ratio of the 30,000 to 70,000 subunits appears to be considerably greater than 1. This is because even the purest preparations available appear to contain a 30,000 molecular weight impurity, which is not separated from the subunit of the dehydrogenase on Sephadex or on acrylamide gels.

Micro-Evaluation

Abstract The work at RAPRA has shown that it is perfectly possible to mix 1 g batches of compound and obtain a variety of physical measurements on the products. This especially of value when only a small amount of the polymer is available as in studies on experimental materials, where the polymer itself is costly, or where it is required to investigate the effect of costly additives. For a number of years, work of this nature has been continued in the authors' laboratories, continually perfecting the apparatus and techniques, and the results quoted above are typical of those obtained on a range of experimental polymers and additives.