Neutron Stars with a Quark Core. II. Basic Integral and Structural Parameters

A broad sample of computed realistic equations of state of superdense matter with a quark phase transition is used to construct a series of models of neutron stars with a strange quark core. The integral characteristics of the stellar configurations are obtained: gravitational mass, rest mass, radius, relativistic moment of inertia, and red shift from the star's surface, as well as the mass and radius of the quark core within the allowable range of values for the central pressure. The parameters of some of the characteristic configurations of the calculated series are also given and these are studied in detail. It is found that a new additional region of stability for neutron stars with strange quark cores may exist for some models of the equation of state.     

Stochastic variability in the atmospheric activity of Jupiter

The atmospheric activity of Jupiter exhibits quasi-periodic character attributed to the stochastic nature of the involved mechanisms. Periodicities between 4–33 years are obtained employing four spectrum analysis methods, (power spectrum employing the Blackman-Tukey window, maximum entropy, Fourier, autocorrelation), whilst, their significance and their stationarity has been established with the application of general statistical tests (Kolmogorov-Smirnov, one sample and two sample test, randomness test, chi-square, various orders of autoregressive process, analysis of truncated records).Deceased.     

Theoretical Modeling of the Regular Olivine Intergrowths in Mimetic Paramorphs from Ringwoodite and Wadsleyite

This work presents the results of theoretical modeling of regular misorientations of olivine grains in mimetic paramorphs from ringwoodite and wadsleyite, whose formation is expected during the rise of material from the mantle transition zone. The coordinates of the axes and angles of misorientation, which characterize ten operations of alignment in the pair intergrowths of olivine grains, eight of which are twins, are calculated. Possible conditions for the formation of the predicted mimetic paramorphs and the chances of their preservation are discussed. The calculated orientations are compared with the known olivine twin laws.     

Hydrodynamics and sediment dynamics of The Wash embayment, eastern England

Water and sediment movement in The Wash embayment has been determined from an extensive set of data, consisting of tidal current readings and suspended sediment concentration measurements. Instantaneous and residual currents in the embayment show a distinct lateral inhomogeneity, whereas vertically the water column is almost homogenous. The central deep water area (30–40 m) of the embayment is dominated by a residual landward water movement, whilst on the margins, the residual movement is seaward. Sediment is supplied predominantly in suspension from the north, through the northern extremity of Boston Deep. Suspended sediment pathways are coincident with the spring tide water movements and the subtidal channels act as the main conduits. Approximately 6·8 × 10⁶ tonnes yr^?1 of suspended sediments are supplied to the embayment from offshore areas. Bedload sediment supply is of lesser importance, ～ 1·4 × 10⁴ tonnes yr^?1. Whereas suspended sediment movement appears to be the dominant mode of transport throughout the embayment, bedload transport is important in reforming the sea bed into a variety of bedforms which are particularly well developed on the margins of channels and shoals.     

Toxic chemicals in Canadian fish-eating birds

Cross-country comparison of DDE and PCB residue levels in cormorant, gull and tern eggs in Canada reveal that bird populations at the Great Lakes are most contaminated with those pollutants. DDE levels have been correlated with reproductive failure in Double-crested Cormorants in the Great Lakes with eggshell thinning as a major factor. Low reproductive success in Herring Gull colonies at Lake Ontario is associated with high chlorinated hydrocarbon levels in eggs. Fish-eating birds in the Wabigoon River system, northwestern Ontario, are among the most known mercury contaminated birds. It is suggested that the effects of mercury on the reproduction of fish-eating birds should be further examined there.Fish-eating birds occupy the highest levels of the food web and magnification of toxic chemicals through prey organisms in this web makes those birds vulnerable to the effects of environmental contaminants. Since fish-eating birds are present everywhere in Canada's freshwater and marine habitats and occupy various niches there, they may serve as pollution indicators in various food chains of our aquatic environment. Colonial birds are especially valuable indicators as pollution effects on total bird populations can be studied. Baseline information on fish-eating bird populations should now be collected everywhere in Canada for measuring present and future effects of environmental pollutants, as well as other man-made disturbances on their populations.     

Ar–Ar age determinations of eclogitic clinopyroxene and garnet inclusions in diamonds from the Venetia and Orapa kimberlites

Ar–Ar age measurements are reported for selected eclogitic clinopyroxene and garnet inclusions in Orapa diamonds and clinopyroxene inclusions in Venetia diamonds. Laser drilling of encapsulated clinopyroxene inclusions within Venetia diamonds released a maximum of 3% of the total ⁴⁰Ar, indicating little diffusive transfer and storage of radiogenic ⁴⁰Ar at the diamond–inclusion boundary. Apparent ages obtained during stepped heating of three diamonds are consistent with diamond crystallisation occurring just prior to the kimberlite eruption 520 Ma ago. Stepped heating of three clinopyroxene-bearing Orapa diamonds gave ages of 906–1032 Ma, significantly above the eruption age, but consistent with previously determined isotopic ages. A few higher apparent ages hint at the presence an older generation of Orapa diamonds that formed >2500 Ma ago. Orapa garnets also contain measurable K contents, and record a range of ages between 1000 and 2500 Ma. The old apparent ages and lack of significant interface ⁴⁰Ar released by the laser probe, suggests that pre-eruption radiogenic ⁴⁰Ar and mantle-derived ⁴⁰Ar components are trapped in microinclusions within the pyroxene and garnet inclusions.     

Post-breakup basaltic magmatism along the East Greenland Tertiary rifted margin

Mafic and ultramafic intrusions in East Greenland adjacent to the offshore Greenland–Iceland ridge were emplaced 5–9 My after continental breakup at 55 Ma [1]. Rare earth element (REE) concentrations determined by secondary ion mass spectrometry are reported for cumulus clinopyroxene from these intrusions, and the data are used to estimate REE abundance in equilibrium melts using available partitioning data. Estimated equilibrium melts from intrusions have strongly fractionated REE patterns with Nd/Dy(N) in the range 2 to 5.6 and Yb/Dy(N) 0.55 to 0.92, similar to values for coeval basalts. These melts have markedly higher Nd/Dy(N) than earlier breakup related flood basalts. The moderately low Yb/Dy(N) for the post-breakup volcanism is indicative of residual garnet in the source, while their high Nd/Dy(N) ratios can best be explained by aggregating low degree melts from a light-REE-enriched garnet- and spinel-bearing mantle source. We also report He, Sr, and Nd isotopic data for the intrusions. The highest ³He/⁴He ratios (>10 R/R_a) are found in the samples whose REE data reflect the largest proportion of melts from a garnet-bearing source, and having Sr and Nd isotopic compositions identical with the radiogenic Sr and unradiogenic Nd isotope end of the Iceland compositional field. There is no indication of a MORB-type mantle in the source of the intrusions. We postulate that post-breakup volcanism along the East Greenland coastline reflects the increasing proximity of the mantle plume to the East Greenland continental margin. The low degree of melting at high mean pressure inferred for the parental melts for the intrusions may reflect re-thickening of the lithosphere, which in turn was caused by the vigorous volcanism during breakup, with accompanying depletion of upper mantle and underplating of the crust at the continental margin.     

Lettau’s Contribution to the Obukhov Length Scale: A Scientific Historical Study

Boundary-Layer Meteorology - It has been repeatedly assumed that Heinz Lettau found the Obukhov length in 1949 independently of Obukhov in 1946. However, it was not the characteristic length scale,...