Relative Mass Difference Research Articles

The maximum oxygen consumption and aerobic scope of birds and mammals: getting to the heart of the matter.

Resting or basal metabolic rates, compared across a wide range of organisms, scale with respect to body mass as approximately the 0.75 power. This relationship has recently been linked to the fractal geometry of the appropriate transport system or, in the case of birds and mammals, the blood vascular system. However, the structural features of the blood vascular system should more closely reflect maximal aerobic metabolic rates rather than submaximal function. Thus, the maximal aerobic metabolic rates of birds and mammals should also scale as approximately the 0.75 power. A review of the literature on maximal oxygen consumption and factorial aerobic scope (maximum oxygen consumption divided by basal metabolic rate) suggests that body mass influences the capacity of the cardiovascular system to raise metabolic rates above those at rest. The results show that the maximum sustainable metabolic rates of both birds and mammals are similar and scale as approximately the 0.88 +/- 0.02 power of body mass (and aerobic scope as approximately the 0.15 +/- 0.05 power), when the measurements are standardized with respect to the differences in relative heart mass and haemoglobin concentration between species. The maximum heart beat frequency of birds and mammals is predicted to scale as the -0.12 +/- 0.02 power of body mass, while that at rest should scale as -0.27 +/- 0.04.

Experimental Manipulation of Egg Size and Hatchling Size in the Cobra, Naja Naja Atra (Elapidae)

We experimentally manipulated eggs of Naja naja atra by partially removing yolk (approximately 15% of the total egg wet mass) from the freshly laid eggs to test the effect of such a manipulation on hatchling traits. Hatchlings from treated and control eggs took nearly the same time to complete embryonic development. Experimentally treated eggs produced size-reduced hatchlings. However, when shell excluded egg mass is statistically kept constant miniaturized hatchlings had slightly but significantly larger total dry body mass than did their control sibs. Relatively more yolk remained unutilized at the time of hatching in miniaturized hatchlings. Since no significant difference in body size or carcass size was found between miniaturized and control hatchlings when shell-excluded egg mass is kept constant, the difference in residual yolk dry mass explained much of their difference in dry body mass. The relative difference in residual yolk dry mass also explained much of the difference in lipid mass, energy contents and residual yolk ash mass between miniaturized and control hatchlings.

Space-time description of neutrino flavor oscillations

Recently the issue of EPR-like correlations in the mutual probability of detecting a neutrino together with an accompanying charged lepton has received a new impetus. In this paper we describe this effect using the propagators of the particles involved in Schwinger's parametric integral representation. We find this description more simple and more suitable to the purpose than the usual momentum-space analysis. We consider the cases of a monochromatic neutrino source, wave packet source, and neutrino creation in a localized space-time region. In the latter case we note that the space-time oscillation amplitude depends on the values of the neutrino masses, and becomes rather small for large relative mass differences (mass hierarchy). We obtain the expressions for the oscillation and coherence lengths in various circumstances. In the region of overlap our results confirm those of Dolgov et al.

Production of highly enriched isotopes at the electromagnetic plants with high dispersion

An electromagnetic isotope separator complex is operated at the Institute of Nuclear Fusion, Russian Research Center, “Kurchatov Institute”. The high dispersion (up to 40 mm per 1% relative difference in mass) and other parameters of these units allow the production of isotopes with very high enrichment. Several investigations related to achieving maximum enrichment of isotopes are reported, along with studies on maximizing both enrichment and production yields.

Isotopic Approximation to Ordinary Diffusion Coefficients in Multi-component Mixture

By making use of the isotope approximation; neglecting squares of relative mass differences among the isotopes, the authors derived analytically approximations to ordinary diffusion coefficients in a 3- and 4- component isotope mixture. Moreover, approximations to multi-component diffusion coefficients were given on the analogy of those to the 3- and 4-component coefficients, and these approximations were verified to satisfy constrains on the exact ordinary diffusion coefficients.For 4-component mixture of uranium hexafluoride isotopes, 234UF6- 235UF6- 236UF6- 238UF6, composition dependences of the approximation were equal to those of the exact diffusion coefficients. In addition, relative errors between the exact and the approximations were less than 0.2% for 5-component mixture of krypton 80–82-83-84-86 isotopes.

Explicit Approximation to Thermal Diffusion Factor in Isotopic 3-component Mixture

When a gas mixture consists of isotopes and squares of relative mass differences among the isotopes are small enough to be negligible, an approximation to a thermal diffusion factor in a 3-component mixture was derived analytically and was found to be the same as the binary thermal diffusion factor. Relative errors between exact and the approximation of the thermal diffusion factor in a 3-component argon 36–38-40 isotope mixture were less than −0.01.

Menopause-associated differences in female fat patterning estimated by dual-energy X-ray absorptiometry

SummaryThe aim of the present study was to describe and quantify the typical changes in fat patterning from premenopause to postmenopause. The absolute and relative fat and lean body mass were estimated using dual-energy X-ray absorptiometry in 461 healthy non-obese females between the ages of 18 and 64 years (x = 43·2). Significant differences (p < 0·001) in absolute and relative fat mass, body weight and body mass index between pre-, peri- and postmenopausal females were observed. Postmenopausal women were significantly heavier (BMI, x = 26·8) than perimenopausal (BMI, x = 24·4) and younger and older premenopausal women (BMI, x = 22·8) and showed significantly higher fat percentages (fat% x = 38·1) in comparison to perimenopausal (x = 36·8) and premenopausal females (x = 31·4). Three indices, upper body composition index, lower body composition index and fat distribution index were calculated. Typical differences in fat distribution patterns between females of differential menopausal status were found. During the premenopausal phase a more gynoid type of fat distribution prevailed, during the postmenopausal phase a more android kind of fat distribution occurred predominantly. The fat distribution during the perimenopause can be interpreted as less gynoid than during the premenopause.

Explicit Approximation to Thermal Diffusion Factor in Isotopic 3-component Mixture.

When a gas mixture consists of isotopes and squares of relative mass differences among the isotopes are small enough to be negligible, an approximation to a thermal diffusion factor in a 3-component mixture was derived analytically and was found to be the same as the binary thermal diffusion factor. Relative errors between exact and the approximation of the thermal diffusion factor in a 3-component argon 36–38-40 isotope mixture were less than −0.01.

Maximal sprint speeds and muscle fiber composition of wild and laboratory house mice

We compared males from four groups of house mice (Mus domesticus), all bred and raised under common conditions in the laboratory: randombred Hsd:ICR; a wild population from Wisconsin; hybrids from lab dams; hybrids from wild dams. Wild mice were much faster sprinters (maximal forced sprint speeds over 1.0 m ranged from 2.38 to 3.34 m/s) than were lab mice (range = 0.89–1.68 m/s). Hybrids exhibited intermediate speeds (range = 1.54–2.70 m/s) and body masses, indicating largely additive inheritance. Type-specific mean muscle fiber cross-sectional areas of the gastrocnemius muscle did not differ significantly among groups. Percentage cross-sectional areas occupied by each of the three identified fiber types also did not differ significantly among groups, nor did they covary with body mass. For their body mass, however, lab mice had smaller gastrocnemius muscles than did wild and hybrid mice, which had muscles of similar size. Although we cannot rule out the possibility that smaller gastrocnemius muscles or slight differences in fiber composition account for the lower sprint speeds of the lab mice, we suggest that differences in unmeasured physiological, behavioral or motivational factors are probably the primary cause. This interpretation is supported by a lack of correlation between individual differences in sprint speed and either relative gastrocnemius muscle mass or muscle fiber type composition.

Identification of a new genetic variant of bovine beta-casein using reversed-phase high-performance liquid chromatography and mass spectrometric analysis.

Various components of the beta-casein fraction from bovine milk were separated by preparative reversed-phase high-performance liquid chromatography (RP-HPLC). They included the genetic variants beta A1, beta A2, beta A3, and an unknown component previously denoted beta X [S. Visser et al., J. Chromatogr. 548 (1991) 361-370]. Tryptic digests of these components were compared by RP-HPLC and most peaks were analysed by mass spectrometry (MS). The tryptic map of beta X was closest to that of beta A1, but with a few mutually different peak components. Electrospray ionisation MS revealed that in the beta X map these components had relative molecular masses of 16 higher than the corresponding ones in the beta A1 map. The main differential peaks represented the 114-169 fragments of beta A1 and beta X, respectively, which were both purified and then cleaved with cyanogen bromide. In the resulting mixtures, each of which contained three fragments, the corresponding peptides representing the 145-156 sequence showed the 16 relative molecular mass difference. In beta X this sequence contained a Leu residue at position 152 instead of the Pro-152 in beta A1, as established by fast-atom bombardment MS-MS. The Leu could be discriminated from an Ile residue by the presence of a side-chain-specific, D-type fragment ion in the MS-MS spectrum of the beta X CNBr peptide. The sequence of the two homologous 145-156 fragments was confirmed by regular amino acid sequence analysis. In accordance with internationally accepted guidelines for the nomenclature of milk proteins, the new genetic variant has been named beta-casein F-5P.

Intestine length in the fishes of a tropical stream: 1. Ontogenetic allometry

We examined the ontogenetic allometry of intestine length in relation to body length and body mass in 21 species of fish from forest streams in Panama. The relationships between log10 intestine length and log10 body length and mass were well described by linear regressions, although some species showed slight curvilinearity. Slopes and intercepts of the linear regressions varied considerably among species. Intestine length was positively allometric in most species, with slopes of the intestine length:body length relationship ranging from 1.09 to 2.11. Relative intestine lengths (intestine length/body length) varied by two orders of magnitude (0.39–38.44) in the data set as a whole, but the variation was about one order of magnitude when species were compared at a common body size. Species in which body mass increased more rapidly with body length had more rapid increases in intestine length with body length. Among omnivorous and carnivorous species compared at the same body length, heavier species had longer intestines. Interspecific comparisons of relative intestine length may produce misleading conclusions unless comparisons are made at a common size and account for differences in relative mass.

Boron isotope variations in nature: a synthesis

The large relative mass difference between the two stable isotopes of boron, 10B and 11B, and the high geochemical reactivity of boron lead to significant isotope fractionation by natural processes. Published δ11B values (relative to the NBS SRM-951 standard) span a wide range of ≈ 90‰. The lowest δ11B values around — 30‰ are reported for non-marine evaporite minerals and certain tourmalines. The most 11B-enriched reservoir known to date are brines from Australian salt lakes and the Dead Sea of Israel with δ11B values up to +59‰. Dissolved boron in present-day seawater has a constant world-wide δ11B value of + 39.5‰. In this paper, available δ11B data of a variety of natural fluid and solid samples from different geological environments are compiled and some of the most relevant aspects, including possible tracer applications of boron-isotope geochemistry, are summarized.

Isotopic mass effects in sputtering: Dependence on fluence and emission angle

The isotopic composition of the flux of sputtered neutrals was measured for low primary-beam fluence increments (< 1 × 1015 Ar-ions/cm2) and different emission angles (0 ° to 80 °) by means of sputtered-neutral mass spectrometry. For germanium and molybdenum, the sputtered flux is initially enriched in the lighter isotopes by a factor of about 1.05 for two isotopes with a relative difference in mass of 8%. This initial enrichment gradually decreases during sample erosion and a steady-state value is reached upon sputter removal of a layer of 10–15 nm. The light-isotope enrichment is independent of the emission angle from 0° to about 60°, but is slightly smaller for larger angles.

High-precision measurements of isotopic fractionation in palladium

The uncertainties that are associated with atomic weights may be constrained by natural variations in the isotopic abundances of the element as well as by the accuracy of the experimental measurements. Isotopic fractionation is dependent on the relative mass difference between the isotopes, and therefore is likely to be more important in elements of low atomic number. However, an isotopically fractionated sample of palladium from a precious metal concentrate from the Bushveld Igneous Complex in South Africa has been reported in the literature. The sample was isotopically fractionated by 3.8% per mass unit, with the enrichment occurring in the heavier isotopes. The source of the fractionation was unknown although the sample had undergone extensive processing. The fractionation of the original sample from the Bushveld Igneous Complex has now been redetermined by the double spiking method using a 104Pd— 108Pd double spike. A fractionation of 3.6 ± 0.1% per mass unit was measured, which confirmed the limitation of 1 part in 10 4 on the accuracy with which the atomic weight of palladium can be stated. Another six palladium samples taken from different locations and representing different stages of industrial purification were also analysed, but their isotopic composition was identical to the terrestrial standard. Thus at this time only one sample of isotopically fractionated palladium has been identified, and this is probably a result of natural processes rather than industrial purification.

Saturniid and Sphingid Caterpillars: Two Ways to Eat Leaves

We demonstrated allometric differences in relative head mass in different instars of 12 species of Saturniidae and 14 species of Sphingidae. The differences were related to the different ways in which individuals from the two families ate their respective host plants and to the different properties of the hosts that tended to be favored by each lepidopteran family. The saturniids tended to have various simple cutting methods, while the sphingids tore and crushed the food, so that in the former, ingested food was in the form of relatively large uniformly sized pieces, and in the latter it was apparently well masticated. Saturniid mandibles were short and simple, while sphingid mandibles were long, toothed, and ridged in a variety of complex ways. The food of saturniids tended to consist of old, tough, tannin—rich leaves, while that of sphingids was softer, younger, and contained small toxic molecules. The generalists within each group tended to be similar to one another, while the specialists (which occurred more frequently among the sphingids) had very characteristic mandibles, each of unique design. One sphingid species feeding on a vine with characteristically very tough leaves had the "saturniid" design of mandibles. The features typically of the two groups of caterpillar are discussed in relation to feeding strategy, digestion, avoidance of plant "defenses," and rapidity of ingestion.

Contribution of internal and external carotid beds to common carotid artery input impedance in the dog.

The input impedance of the canine common carotid artery has been obtained using high fidelity pressure and flow recordings at the level of the superior thyroid artery. From the impedance spectra initially, and following internal and external carotid artery occlusion, separate estimations of internal carotid, external carotid and external/internal collateral bed impedances were derived by the use of network theory. Studies were carried out on six dogs. The common carotid input resistance was 10.98 +/- 1.42 (S.E.M.) X 10(6) kN.m-5.s, while those for the internal, external and collateral beds were 48.80 +/- 7.12, 14.94 +/- 2.37 and 171.42 +/- 46.83 X 10(6) kN.m-5.s respectively. The impedance spectrum of the common carotid, external carotid and collateral beds were of a high impedance type with major reflexions, while that for the internal carotid bed was of low impedance type with much less reflexion. On standardization of impedance for tissue mass the resistance levels became 17.44 +/- 2.91 X 10(6) kN.m-5.s. 100 g-1 for internal and 85.41 +/- 4.75 X 10(6) kN.m-5.s. 100 g-1 for external carotid beds. Thus, common carotid input impedance differences between dog and man are due to differences in relative mass of tissue perfused by internal and external carotid arteries, rather than to different peripheral-bed characteristics in the two species.

Contribution of Tissues to Body Mass in Elk

A model for Reference Man has been developed to express the relative contribution of tissues and organs to total body mass in humans. The objectives of this study are to (1) develop a Reference Elk model for the Rocky Mountain elk (Cervus elophus nelsoni) and (2) compare the model developed with similar data for Reference Man and mule deer. Five female elk were collected from the eastern slope of the Jemez Mountains of New Mexico. Relative weights of tissue and organs were determined. Relative amounts of skeletal muscle, bone, and lung tissues are similar between the three species. Tissues showing the greatest differences in relative mass were the adrenals and brain. The brain of man contributed 13 times more to total body mass than did the brain of elk. Percentages for most other tissues and organs varied by a factor of about 2 to 3 between species. (RJC)

Population-based reference values for lecithin-cholesterol acyltransferase (LCAT)

Plasma unesterified cholesterol is converted to cholesteryl ester by the enzyme lecithin-cholesterol acyltransferase (LCAT). Plasma levels of LCAT were measured by a sensitive double antibody radioimmunoassay in a sample from an adult employee population, ages 20–59 years, in the Pacific Northwest. After adjusting for differences in relative body mass, women had significantly higher LCAT levels (5.90 ± 1.06, n = 154) than men (5.49 ± 0.89, n = 83). For ages 20–59 years, LCAT levels showed a slight association with age: r = 0.13 for men and 0.29 for women. LCAT was positively correlated with relative body mass, total cholesterol, and LDL cholesterol. Men who smoked cigarettes had significantly lower LCAT mass than men who did not smoke cigarettes. No statistical differences in mean LCAT values were found between drinkers and nondrinkers. The 5th percentile LCAT value was 4.3 μg/ml for both men and women not using hormones. The 95th percentile value was 7.3 μg/ml for men and 7.8 μg/ml for women regardless of hormone use. Subjects phenotypically LCAT-deficient by clinical criteria and by the absence or near absence of LCAT activity had levels of LCAT mass well below the reference values: 0.73 ± 0.70, range 0.10 μg/ml to 2.65 μg/ml, n = 20. Parents or children of LCAT-deficient subjects, i.e., obligate heterozygotes for familial LCAT deficiency, had reduced levels: 3.59 ± 0.69, range 2.59–4.61 μg/ml, n = 19.

Separation and detection of lipoproteins in human serum by use of size-exclusion liquid chromatography: a preliminary report.

Components of human serum can be separated on the basis of differences in relative molecular mass by using size-exclusion "high-performance" liquid chromatography. Lipoproteins in fractions of the eluate can be quantitated by conventional chemical and enzymatic methods. Alternatively, if lipoproteins in the serum are selectively prestained with diformazan dye, the column effluent can be monitored spectrophotometrically at 580 nm, so that only the lipoprotein components of serum are detected. Samples of purified low-density lipoproteins, so stained and analyzed, provide peak-area values that are proportional to their concentration as evaluated by chemical methods. With this technique, the various lipoprotein classes can be quickly separated and their concentration estimated. These techniques should prove useful in clinical and research laboratories.

Molecular diffusivities of H2 16O, HD16O, and H2 18O in gases

Isotopic effects on the molecular diffusion coefficients of H2 16O, HD16O, and H2 18O have been determined by two independent methods. In the first one, the evaporation of liquid water under controlled laminar flow conditions was investigated. In the second one, the transport of water vapor through a diffusion tube was measured. The molecular diffusion coefficient of natural water vapor in nitrogen was redetermined. At 21 °C and P=760 Hg mm, D=0.244±0.004 cm2/sec. For the isotopic molecules we have DHD16O/DH216O=0.9757±0.0009 and DH218O/DH216O=0.9727±0.0007. Agreement between the data obtained in the pure gas phase experiment and the two-phase experiment shows that the condensation coefficients of the isotopically substituted molecules are identical. Interpretation of the isotopic effects on molecule diffusivities indicates that the relative mass differences between H2 16O, HD16O, and H2 18O alone cannot account for the experimental results. This is more important for the D–H substitution in which the asymetric molecule HD16O is formed. Qualitatively, the displacement of the center of gravity of the molecules H2 16O and HD16O in this substitution can explain the observed effect. Interpretation of these isotopic effects in terms of simple kinetic theory of gases indicates that for rigid spherical molecule models with diameters Γ we have the relation ΓH218O&amp;lt;ΓH216O&amp;lt;ΓHD16O. We calculate from the experimental data ratio of the coefficients of diffusion of the three isotopic molecules in air DHD16O/DH216O=0.9757±0.0009 and DH218O/DH216O=0.9727±0.0007.