Brans-Dicke cosmology,II

We discuss the implications of the Brans-Dicke scalar-tensor theory for cosmology with particular emphasis on the primordial element abundances that would obtain. Two general classes of models are found. Models of one class expand through the nuclear burning stage slightly more rapidly than the general relativistic case: models of the other class may expand at any rate whatsoever. The first class of models yeilds primordial abundances of D, He³ and He⁴ in agreement with their general relativistic values if the present mass density is low. High-density cosmologies, however, would produce too much He⁴. The second class of models yields element abundances which are far too high unless the expansion rate was quite large: in this case no He⁴ at all is produced. Finally, we determine the rate of change of the constant of gravitationG at the present epoch. For all but a very small class of models is negative at the present epoch. Models with positive values of at the present epoch produce no primordial He⁴ whatsoever, and have ages significantly lower than the corresponding general relativistic ages.     

Contrasting interactions of sodium and potassium with H<Subscript>2</Subscript>O in haplogranitic liquids and glasses at 200 MPa from hydration–diffusion experiments

This study examines hydration–diffusion in the metaluminous haplogranite system at 200 MPa H₂O and 800–300°C. At 800°C hydration is accompanied by melting and uphill diffusion of sodium from anhydrous glass toward the region of hydration and melting, whereas potassium diffuses away from the hydration front and into anhydrous glass. Silicon and aluminum are simply diluted upon hydration. There is no change in molecular Al/(Na + K) throughout the entire hydration-diffusion aureole and, therefore, (1) there is no loss of alkalis to the vapor, and (2) K migrates to replace Na in order to maintain local charge balance required by ^IVAl. Alkali diffusion occurs over a viscosity contrast from 10^4.1 Pa s in hydrous liquid to 10^11.8–10^13.5 Pa s in anhydrous glass. From these results, we interpret that: (1) Na is structurally or energetically favored over K as a charge-balancing cation for ^IVAl in hydrous granitic liquids, whereas the opposite behavior has been observed for anhydrous melts, and (2) the diffusion of alkalis through silicate melts is largely independent of viscosity. Results from 600°C are similar to those at 800°C, but hydration at 300°C involves a loss of Na and concomitant increase in molar Al/(Na + K) in the hydration zone due to hydrogen-alkali exchange between fluid and glass. Hydration behavior at 400°C is transitional between those at 300°C and 600°C, suggesting that the change in hydration mechanism occurs near the glass transition.     

Airborne imagery of ocean mixed-layer convective patterns

Airborne infrared and synthetic aperture radar imagery collected over the Gulf Stream are used to examine the surface patterns of small-scale thermal convection and wind-driven Langmuir circulation. These patterns have a thermal contrast of ～0.25 °C, which is roughly an order of magnitude larger than predicted by large-eddy simulations but consistent with the effect on surface temperature of surfactant accumulations induced by mixed-layer eddies.     

An analysis of the distribution of boulders in the vicinity of small lunar craters

Nine Orbiter 3 high-resolution photographs were examined at three sites for distributions of boulders around craters 110 m in diameter; three kinds of distributions were noted. Some had boulders inside and far outside (designated), others had boulders only inside or on their ramparts (), and some had no detectable boulders (). Additionally, shapes or morphologies of craters were classified according to their resemblance to one of three Jaffe models (1965); a third classification involved the depth of particulate overlay (Jaffe, 1965). Crater morphologies were classified (A) if they were relatively shallow with sharp, raised rims, (B) if they were rimless and shallow, and (C) if they were relatively deep and had low, broad rims. The data suggested that there were strong relationships between crater types and boulder distributions in which, generally, A-type was related to the-distribution, B-type to-distribution, and C-type to-distribution. Plots of numbers of craters of each crater type and each kind of boulder distribution versus steps of overlay for each site and for the totality of craters considered indicated that neither boulder distribution nor crater type represented orderly progression of age or erosional evolution. The apparent overlays for the A's and C's and for the's and's were similar, implying similar ages or stages of erosion. It is suggested that they represent two kinds of primary craters and that the A's are of impact origin while the C's are of volcanic origin. The B's probably represent later stages of erosion of the C's and possibly of some A's.Now at the University of Maryland.Receipt delayed by postal strike in Great Britain.     

Sulfur flows of Ra Patera,Io

Voyager 1 imaging data have been used to investigate the color and morphology of several radial flow-like features at Ra Patera, a broad volcanic structure at approximately 8° latitude and 325° longitude on the Galilean satellite Io (J1). It was found that downstream progressions of flow color and morphology are consistent with lava of a predominately sulfur composition cooling radiatively and erupting in the range of 470 to 520°K at effusion rates at 10¹⁰ to 10¹¹ cm³/sec. This implies global resurfacing rates by volcanic flows on Io of the order of 1 cm/year. Calculated energy content and effusion rates for flows at Ra Patera, using the physical parameters of sulfur, are of the order of the largest known terrestial basaltic eruptions and are consistent with calculations of globally available energy.     

Spatial and temporal variations of EUV coronal bright points

This paper reports results of an analysis of Skylab observations of coronal bright points made in EUV spectral lines formed in the chromosphere, chromospheric-coronal transition region and corona. The most important result is that the observed bright points exhibited large variations in EUV emission over time scales as short as 5.5 min, the temporal resolution of the data. In most cases strong enhancements in the coronal line were accompanied by strong enhancements in the chromospheric and transition region lines. The intensity variations appear to take place within substructures of the bright points, which most likely consist of miniature loops evolving on time scales of a few minutes. Coronal cooling times derived from the data are consistent with an intermittent, impulsive coronal heating mechanism for bright points.     

THE BEAVER-HARRISON,BEAVER COUNTY,UTAH L6 CHONDRITE

The Beaver-Harrison, Utah chondrite (find July 24, 1979), a single, shock-veined stone of 925 grams, consists of major olivine (Fa_25.0), low-Ca pyroxene (En_77.3Fs_21.1Wo_1.6) and metallic nickel-iron; minor troilite and plagioclase (Ab_82.6An_11.1Or_6.3), accessory high-Ca pyroxene (En_47.0Fs_8.5Wo_44.5), chromite (Cm_8.7Sp_10.6Uv_9.4Pc_0.6Hc_0.7), chlorapatite and whitlockite; and hydrous ferric oxide of terrestrial weathering origin. Mineral compositions indicate L-group classification, and homogeneity of minerals, highly recrystallized texture and presence of clear plagioclase suggest that the meteorite belongs to petrologic type 6.     

Scattering in the Atmosphere of Venus. I. Line profiles and curves of growth for isotropic scattering

We have computed line profiles and curves of growth for both reflected and transmitted radiation for typical lines in CO₂ bands (in the photographic infrared) which occur in the spectrum of Venus. In our model the pressure variation with altitude was considered and the base of the cloud deck was set at the 2 bar level. The temperature was held constant at 250K and a Voigt profile was used for the lineshape. We also assumed that the scale height of the cloud particles was equal to the scale height of the gas. The calculations were made for four values of the scattering optical thickness (τ_c = 0.1, 1.0, 10, and 100) using a continuum single scattering albedo $\text{ω}{}_{\mathrm{<mtext>c</mtext>}}\text{= 0.9975}$ (which gives a Bond albedo of 0.896 for τ_c = 100, the value observed for Venus at these wavelengths). Curves of growth are also presented for reflected radiation which has been averaged over the visible disk for three values of the Venus phase angle (0, 86, and 166°).     

Zero velocity surfaces for the general planar three-body problem

The angular momentum and the energy integral of the planar three-body problem are used to establish regions of the physical space where motion is allowed to take place. Although forbidden regions exist for both negative and positive values of the energy of the system, the known integrals of the motion always allow for at least one of the three bodies to escape.     

Do 2006/7/EC European Union Bathing Water Standards exclude the risk of contact with Salmonella or Candida albicans?

The purpose of this study was to evaluate the efficiency of the recent (2006) European Union Directive concerning the management of bathing water quality to exclude the presence of pathogens from complying waters. Coastal water samples were classified according to the Directive. 2.5% of ‘excellent’ water contained Salmonella and 39.2% Candida albicans 11.8% of samples in category ‘good’ were Salmonella positive and 35.2% were C.albicans positive. When the USEPA criterion for marine waters was applied to the same dataset, fewer samples complied, however 6.0% of the complying samples contained Salmonella. The results suggest that the bacterial indicator threshold levels for marine recreational water quality of the 2006/7/EC European Union Directive do not fully exclude contact of bathers with dangerous pathogens. Enterococci, if used as the sole index, appear to form a more reliable proxy of the risk of contact with Salmonella.