Hesperornithiformes (Aves: Ornithurae) from the Upper Cretaceous Pierre Shale,Southern Manitoba,Canada

A historical collection of hesperornithiform fossils from the Gammon Ferruginous, Pembina, and Millwood members of the Pierre Shale (Campanian, Upper Cretaceous) in southern Manitoba, Canada, was examined to revise their taxonomy. Only two species of Hesperornis have been recognized in previous studies on the Pierre Shale in Manitoba, but our study recognizes six species of two genera, including H. lumgairi sp. nov. H. regalis is the most common species but absent in the uppermost unit within the studied sequence. The result of this study supports the paleobiogeographic subdivision of the Campanian vertebrate fauna within the Western Interior Seaway, but not the faunal boundary that distinguishes the avian fauna of Manitoba from that of South Dakota and Kansas.     

Geochemistry of tin in rivers and estuaries

On the basis of measurements from a large number of rivers from pristine and polluted regions, we estimate the riverine fluxes of tin to the oceans to be 0.76 × 10⁶molyr⁻¹ for the dissolved fraction and 300–600 × 10⁶ mol yr⁻¹ for the paniculate fraction. The paniculate flux agrees with the flux calculated from denudation rates. Estuaries were found not to have a large effect upon the transport of tin to the oceans. Evidence for the remobilization of tin was found in an estuary that is highly polluted with tin from mining and smelting activities. Monobutyltin was found to be present in polluted estuaries and is presumed to be a degradation product of tributyltin additives to antifouling paint.     

Stellar subsystems of the galaxy NGC 2366

Hubble Space Telescope archive data are used to perform photometry of stars in seven fields at the center and periphery of the galaxy NGC 2366. The variation of the number density of stars of various ages with galactocentric radius and along the minor axis of the galaxy are determined. The boundaries of the thin and thick disks of the galaxy are found. The inferred sizes of the subsystems of NGC 2366 (Z _thin = 4 kpc and Z _thick = 8 kpc for the thin and thick disks, respectively) are more typical for spiral galaxies. Evidence for a stellar halo is found at the periphery of NGC 2366 beyond the thick disk of the galaxy.     

Diarrhetic shellfish poisoning in Narragansett Bay

A two-year survey for diarrhetic shellfish poisoning (DSP) was conducted in Narragansett Bay using the mouse assay method. The suspected causative organisms,Dinophysis spp., were monitored at the same time. Only one shellfish sample, in September 1984, yielded an unequivocal positive result at a time when the dinoflagellate population was dominated byD. acuminata. False positive results were suspected in May, when the mussels appeared sexually matured, and in, the summer of 1985, at the time of an unusual massive picoplanktonic bloom. Evidence of toxin production byD. acuminata was obtained from an almost monospecific sample; we calculated that over 5.4×10⁵ cells would be necessary to produce one mouse unit. The specificity and sensitivity of the assay method are questioned and improvements for DSP detection are suggested.     

The structure of the <Emphasis Type="Italic">AD</Emphasis> diagram for the hyades cluster

The Hyades Cluster is used to analyze details of the AD-diagram method developed in our earlier works and applied to the corona of the Ursa Major stream. Hipparcos data are used to analyze the kinematics of the Hyades Cluster and determine its apex. Evidence for rotation of the cluster is presented.     

The eclipsing variable CM Dra: Surface activity and orbital elements

A long series of observations of the low-mass eclipsing system CM Dra (M ₁, M _⊙<0.25M _⊙, dM4.5e, V=12.9^m, P _orb=1.27^d) was obtained in 1996–1997 as part of the international TEP (Search for Transits of Extrasolar Planets) project. The observations were obtained on the 70-cm telescope of the Astronomical Observatory of Ural State University with an automatic two-star photometer. The total duration of the data series was 155 h. We construct and analyze a master light curve, including calculation of the photometric and absolute orbital elements. Evidence for surface activity was detected. The light curve of CM Dra outside eclipses shows low-amplitude (0.024^m) brightness variations, suggesting the presence of a starspot on one of the components. The amplitude of these variations stayed the same over 20 years, but the phase of the brightness maximum shifted by one-third of the orbital period, possibly reflecting changes in the longitude or asymmetry of a single large polar spot. We detected four flares whose energies were factors of several hundred higher than those of solar flares. The derived flare rate agrees with data for CM Dra in the literature but is much lower than is typical for Population I stars in our Galaxy.     

Synthesis and characterization of high-pressure and high-temperature sphene (CaTiSiO5)

Sphene (CaTiSiO₅), a calcium titanosilicate ceramic has been prepared from a powder mixture of CaCO₃, TiO₂ and SiO₂ using vibro-milling for homogenization and activation of precursors. During the high-pressure and high-temperature synthesis (HPS) process at 4 GPa and 1,200 °C, sphene undergoes into phase transition, from room-temperature phase P2₁ /a to high-temperature phase A2/a. Evidence of that structural phase transition is given in this paper using infrared, Raman spectroscopy and X-ray powder diffraction. Rietveld refinement was employed to get the structural information of the synthesized powder. The most important structural change due to phase transition, the disappearance of the characteristic out-of-center distortion of the Ti atom and moving to the center of octahedra, was confirmed. HPS is an effective method for producing full-dense ceramics without any additives. Reduction of particle size occurred during high-pressure compaction. Microstructure and particle size of both phases were analyzed by scanning electron microscopy.     

Habitat requirements for submerged aquatic vegetation in Chesapeake Bay: Water quality, light regime, and physical-chemical factors

We developed an algorithm for calculating habitat suitability for seagrasses and related submerged aquatic vegetation (SAV) at coastal sites where monitoring data are available for five water quality variables that govern light availability at the leaf surface. We developed independent estimates of the minimum light required for SAV survival both as a percentage of surface light passing though the water column to the depth of SAV growth (PLW _min) and as a percentage of light reaching reaching leaves through the epiphyte layer (PLL _min). Value were computed by applying, as inputs to this algorithm, statistically dervived values for water quality variables that correspond to thresholds for SAV presence in Chesapeake Bay. These estimates ofPLW _min andPLL _min compared well with the values established from a literature review. Calcultations account for tidal range, and total light attenuation is partitioned into water column and epiphyte contributions. Water column attenuation is further partitioned into effects of chlorophylla (chla), total suspended solids (TSS) and other substances. We used this algorithm to predict potential SAV presence throughout the Bay where calculated light available at plant leaves exceededPLL _min. Predictions closely matched results of aerial photographic monitoring surveys of SAV distribution. Correspondence between predictions and observations was particularly strong in the mesohaline and polythaline regions, which contain 75–80% of all potential SAV sites in this estuary. The method also allows for independent assessment of effects of physical and chemical factors other than light in limiting SAV growth and survival. Although this algorithm was developed with data from Chesapeake Bay, its general structure allows it to be calibrated and used as a quantitative tool for applying water quality data to define suitability of specific sites as habitats for SAV survival in diverse coastal environments worldwide.     

Microvariability of line profiles in the spectrum of the star ι Her

We present the results of a search for and analysis of line-profile variations in the spectrum of the star ι Her. The observations were acquired with the 1.8 m telescope of the Bohyunsan Optical Astronomy Observatory (Republic of Korea) in May–June 2004. We obtained 69 spectra of the star with signal-to-noise ratios ≈300 and a time resolution of 5–7 min. Profile variability was revealed for six lines of HI, HeI, and SiIII, in the central parts of the lines. The variability amplitude is ≈(1–2)% in units of the intensity of the adjacent continuum. Evidence was found for cyclic variations of the lines, with periods from ≈7^h to ≈2.9^d. We conclude that ι Her belongs to the group of slowly pulsating stars.     

Hydrogen concentration profiles in quartz determined by a nuclear reaction technique

The nuclear reaction ¹⁹F(¹H, αγ) ¹⁶O has been used to determine the hydrogen concentration in natural and synthetic quartz samples. The depth-profile of the hydrogen concentration in these samples has been determined in detail for the smoky and X _o quartzes. These profiles exhibit a region of high hydrogen concentration in the near surface region (down to a depth of ～2000Å), with a lower concentration in the bulk of the sample. The results provide a plausible explanation for the substantial disagreement between previous hydrogen analysis in these quartzes by other techniques. Evidence for hydrogen mobility in crystalline quartz under ion beam bombardment is presented and discussed.     

Prey density requirements of the striped bass,Morone saxatilis (Walbaum), larvae

Striped bass,Morone saxatilis, larvae of 9 DAH (days after hatching) were fed for 16 d with five densities of adults (5–100 l^?1), copepodites (10–200 l^?1), and nauplii (50–1,000^?1) of the copepodEurytemora affinis, and 5-DAH and 10-DAH larvae were fed at seven densities (5–500 l^?1) of brine shrimp,Artemia salina, nauplii. The study determined the effects of prey types and densities on the survival and growth of the fish larvae, and the effects of delaying first feeding from 5 DAH to 10 DAH. The survival and grwoth of the larvae fedE. affinis adults was higher than those fedE. affinis copepodites.E. affinis nauplii were the poorest prey. OneE. affinis adult provided nutrition equivalent to 1.45 copepoditer or 11.12 nauplii. The percentage survival of the larvae was higher for those fedA. salina nauplii thanE. affinis adults at the densities below 67.25 l^?1, but there was no difference at this density or higher. Delaying first feeding from 5 DAH to 10 DAH did not affect percentage survival and size of larvae at the end of the experiments. Because the survival and growth of the larvae increased as the prey density increased, it was difficult to set a point along the regression line as the minimum density requirement level. It may be said that for striped bass larvae, the higher the prey density, the higher the survival and growth, and thus the greater the recruitment success.     

The ion-pair constant and other thermodynamic properties of HCl up to 350°C

Solubilities of silver chloride in aqueous hydrochloric acid solutions have been determined from 100 up to 350°C. From these measurements, the ionisation constant of HC1 has been evaluated up to 225°C. Evidence is presented to show that a protonated silver species, HAgCl₂⁰, exists at 275°C and above. Available experimental data up to 200°C have been firted to Pitzer's equation to generate an algorithm to calculate stoichiometric activity and osmotic coefficients of HCl up to 350°C and concentrations up to at least 3.0 m. Using the present results and those of Wrightet al. (1961), Pearsonet al. (1963) and Lukashowet al. (1976), the dissociation constant (K_d) of HCl as a function of temperature is described by the equation log₁₀K = 2136.898 + 1.020349T−4.5045 × 10⁻⁴T²−50396.40/T−901.770 10g₁₀T (Tin °K) which is valid in the range 25–350°C. Calculated enthalpy (ΔH⁰), entropy (ΔS⁰) and heat capacity change (ΔC_p⁰) functions for HCl dissociation have been rationalized in terms of changing solute and solvent characteristics as temperature is raised.     

Estuarine influence on survival rates of coho (Oncorhynchus kisutch) and chinook salmon (Oncorhynchus tshawytscha) released from hatcheries on the U.S. Pacific coast

While it has long been known that Pacific salmon use estuarine habitat, it has proven much harder to establish that the loss of estuarine habitat results in reduced survival. We used coded-wire tagging of hatchery fish to estimate the survival from release until maturity and related this survival to several indicators of estuarine condition. We found a significant relationship between the survival of chinook salmon (Oncorhynchus tshawytscha) and the percentage of the estuary that is in pristine condition, but no significant relationship for coho salmon (Oncorhynchus kisutch). This supports field observations that chinook salmon use estuarine habitat much more than coho salmon and confirms that the loss of estuarine habitat results in lower survival of chinook salmon.     

Atomic displacements in the normal-incommensurate phase transition in Co-åkermanite (Ca2CoSi2O7)

New in-situ high-temperature X-ray powder diffraction data on the normal-incommensurate phase transition in Co-åkermanite (Ca₂CoSi₂O₇) are presented. Evidence for the phase transition is found in the abrupt change in the thermal expansivity of the c lattice parameter at 220° C. In addition, the c lattice parameter exhibits premonitory effects of the phase transition through the leveling out of the thermal expansivity at temperatures from 87 to 220° C. The c/a ratio for X₂ZSi₂O₇ incommensurate melilites is shown to be constant for a wide variety of compositions. Correlation of the trends in mean atomic positions with c/a ratio and the sigmoidal variation in the c/a ratio for Ca₂CoSi₂O₇ provide insight into the atomic displacements occurring in the melilite structure as a function of temperature. Three temperature regimes are discussed in detail (i.e. temperatures well above T _c, temperatures just above T _c, and temperatures below T _c). The atomic displacements occurring in each temperature regime are correlated with the changes in anisotropy and orientation of the atomic displacement ellipsoids for each site, as well as spectroscopic evidence for the increasing number of Z- and T-site environments.     

The effect of temperature and food density on survival and growth of Menidia peninsulae larvae (Pisces: Atherinidae)

Day of hatch tidewater silversides, Menidia peninsulae, were stocked at 5 fish per liter in 3 1 of seawater at 30‰ and raised for 16 days at 20°, 25° and 30 °C. Food organisms (Brachionus sp. or Artemia nauplii) were maintained at 500, 1,000, 5,000 or 10,000 organisms per 1. The influence of food density on growth of larval M. peninsulae was temperature dependent. At 20 °C, there was no difference in final size of fish based on food densities. But at 25° and 30 °C there was an increase in final body size as food density increased. There were no significant differences in survival among food densities in tests at 20°, 25° or 30 °C. However, for any given temperature and food density, the number of survivors in a replicate affected the final size attained. Optimal culture condition for larval M. peninsulae, considering both survival and growth was determined to be 5,000 food organisms per 1 at 25 °C.     

Frequency dependence of equatorial ionospheric scintillations

Simultaneous observations of amplitude scintillations at 40 MHz, 140 MHz and 360 MHz radiated from ATS-6 satellite at 34° E longitude were made at Ootacamund near the magnetic equator in India. It has been found that the frequency variation of scintillation index (S ₄) isS ₄ ∞f ^?n , withn being about 1·2 only for weak scintillations, i.e., so long as the scintillation index does not exceed 0·6 at the lower frequency. For strong scintillations (S ₄>0·6) where multiple scattering may be present, the exponentn itself is a function of the intensity of scintillation, the scintillation indices at two frequencies are related by:S ₄(f ₁)=S ₄(f ₂) exp [1·3 log(f ₂/f ₁)(1?S ₄(f ₂)] so long asf ₂/f ₁≤3. Thus knowing scintillation index at a given frequency one can estimate the scintillation index at another frequency. This will be of significant importance for communication problems. Evidence is also shown for the reversal of the frequency law in cases of intense scintillations.     

Bedding-parallel shear,thrusting and quartz vein formation in witwatersrand quartzites

Evidence is presented which clearly demonstrates the presence of thrust faults in the gold-bearing sedimentary rocks of the Witwatersrand Supergroup. A package of these rocks subjected to shear strain allowed overlying beds on the northern margin of the Witwatersrand Basin to move outwards in a N-NW direction. Movement took place on ductile shear zones which were parallel to the bedding and often reveal excellent examples of ramp and duplex structures. It has also been established that syntectonic foliation planes were utilized as planes of shear in certain circumstances. Quantitative estimates of strain for the pile, which are of necessity minimum values, give γ ≈ 1. Fluids, from which vein quartz formed, played a critical role in the shear plane movement and may have relieved a portion of the overburden load during deformation.     

Theoretical approach to evaluating plagioclase dissolution mechanisms

The more rapid dissolution of Ca-rich feldspars relative to Na, K-rich feldspars has been attributed to the preferential leaching of Al deep within the feldspar structure. Evidence from surface microanalysis (e.g., Hellmann et al., 2003), however, shows that preferential dissolution of Al is confined to the top layers of the feldspar lattice and that the amorphous surface layer most likely results from precipitation versus dissolution. It is thus critical to examine the extent of preferential Al removal. Here we present a theoretical study of plagioclase dissolution behavior using parameterized Monte Carlo simulations. Two different dissolution mechanisms, a mechanism involving preferential leaching of Al and an interfacial dissolution-reprecipitation mechanism, are tested using compositions representing the entire plagioclase solid solution series. Our modeling results indicate that under the control of the preferential Al leaching mechanism, the influence of (Al, Si) disorder on the dissolution rate is significant. At a fixed composition, an increase in the degree of (Al, Si) disorder yields an increased dissolution rate, with an 8-fold increase in dissolution rate observed for highly disordered albite (An₀) compared to low albite. Increasing anorthite content tends to decrease the variation in the dissolution rate due to disorder. The difference in the dissolution rate of 293 tested oligoclase configurations with a composition of An₂₀ is 3-fold, and the difference is reduced to 2-fold among 107 andesine configurations of An₃₀. Furthermore, feldspar configurations with completely disordered (Al, Si) distributions yield a consistent log-linear dependence of dissolution rate on the anorthite content (An), while other feldspar configurations with modest degrees of (Al, Si) disorder exhibit rates less than this trend. In contrast, when Al removal is confined to the top surface layers, a variety of feldspar configurations with different (Al, Si) disorder but a single fixed composition have similar dissolution rates; and the dissolution rate of Ca-rich feldspars departs positively from its log-linear relationship with anorthite content. This departure occurs around An₈₀ and is in good agreement with previous experimental studies. Subsequent modeling results of aluminum inhibition, ΔG dependence, and formation of altered surface layers in the framework of the interfacial dissolution-reprecipitation mechanism are all comparable with experimental investigations, and these results suggest that an interfacial dissolution-reprecipitation mechanism governs the dissolution of plagioclase feldspars.     

The microstructure of polar ice. Part II: State of the art

An important feature of natural ice, in addition to the obvious relevance of glaciers and ice sheets for climate-related issues, is its ability to creep on geological time scales and low deviatoric stresses at temperatures very close to its melting point, without losing its polycrystalline character. This fact, together with its strong mechanical anisotropy and other notable properties, makes natural ice an interesting model material for studying the high-temperature creep and recrystallization of rocks in Earth's interior. After having reviewed the major contributions of deep ice coring to the research on natural ice microstructures in Part I of this work (Faria et al., 2014), here in Part II we present an up-to-date view of the modern understanding of natural ice microstructures and the deformation processes that may produce them. In particular, we analyze a large body of evidence that reveals fundamental flaws in the widely accepted tripartite paradigm of polar ice microstructure (also known as the “three-stage model,” cf. Part I). These results prove that grain growth in ice sheets is dynamic, in the sense that it occurs during deformation and is markedly affected by the stored strain energy, as well as by air inclusions and other impurities. The strong plastic anisotropy of the ice lattice gives rise to high internal stresses and concentrated strain heterogeneities in the polycrystal, which demand large amounts of strain accommodation. From the microstructural analyses of ice cores, we conclude that the formation of many and diverse subgrain boundaries and the splitting of grains by rotation recrystallization are the most fundamental mechanisms of dynamic recovery and strain accommodation in polar ice. Additionally, in fine-grained, high-impurity ice layers (e.g. cloudy bands), strain may sometimes be accommodated by diffusional flow (at low temperatures and stresses) or microscopic grain boundary sliding via microshear (in anisotropic ice sheared at high temperatures). Grain boundaries bulged by migration recrystallization and subgrain boundaries are endemic and very frequent at almost all depths in ice sheets. Evidence of nucleation of new grains is also observed at various depths, provided that the local concentration of strain energy is high enough (which is not seldom the case). As a substitute for the tripartite paradigm, we propose a novel dynamic recrystallization diagram in the three-dimensional state space of strain rate, temperature, and mean grain size, which summarizes the various competing recrystallization processes that contribute to the evolution of the polar ice microstructure.     

Effects of the herbicide alachlor on larval development of the mud crab,Rhithropanopeus harrisii (Gould)

The effects of the herbicide alachlor, in both technical grade and commercial product form (Lasso), were tested for acute toxicity on larvae of the estuarine crabRhithropanopeus harrisii. The generalized effect is a reduction in survival and a lengthening of developmental time with an increase in concentration. The LC₅₀ values were inversely proportional to exposure time and ranged from 10 to 27 mg l^?1. Lasso was slightly more toxic than technical grade alachlor.