Ingestion of Domoic Acid and Its Impact on King Scallop（Pecten maximus,Linnaeus 1758）

A simple method for spiking formulated feed with domoic acid （DA） was developed in this study. DA feed was prepared by mixing 0.15 mL 100 μg mL-1 DA with 0.1 g formulated feed, and drying the mixture at room temperature for 2 h. The prepared DA feed contained 0.19 pg DA per particle. Of the added DA, 46.72% was retained in the feed. Relatively high DA retention （about 50%） was recorded after DA feed was soaked in water for 2h. Exposure to DA feed for 7d did not cause the increase of tissue DA level of adult king scallop （Pecten maximus） significantly in 60 d. The increase of their gonad index after DA exposure was not significantly different from the control. No significant change in DA level was found in spermary, ovary or fertilized eggs after DA exposure. These results indicated that DA excretion may be more efficient than DA accumulation under the current experimental conditions, and the mechanism of domoic acid incorporation in P. maximus may involve intracellular biotransformation.     

Milankovitch cyclicity recorded from Devonian non-marine sediments

Hydrographically closed basins are sensitive to environmental change at all scales, the influence of climate being particularly strong. Some Devonian basins contain non-marine successions which appear to represent the deposits of such basins. Climatic fluctuations may be recorded by sediments in the form of Milankovitch band cyclicity. Two novel records of climatically related cyclicity are discussed. Well 12/13-1 in the North Sea penetrates a fine-grained Old Red Sandstone succession which is thought to be comparable to the largely lacustrine Middle Devonian deposits of the Orcadian Basin which outcrop onshore. The gamma ray log through the Devonian interval reveals periodic large peaks which correlate with U-rich, fine-grained intervals deposited during periods of greatest lake expansion. The peaks are cyclical; power spectrum of the gamma ray data reveal periodicities of c. 8 and 40 m, which are thought to correlate with the 21,000 yr (precession) and 100,000 yr (eccentricity) Milankovitch cycles. The Sherkin Sandstone Formation of the Munster Basin, SW Ireland, is a thick (> 1000 m) succession of largely alluvial deposits which were deposited by a terminal fan network. Detailed analysis of channel body sandstones and sedimentary structures contained within them reveals a cyclical variation in the dimensions of the bedforms camed by the channels. The same cyclicity is evident in the proportion of channel deposits. This variation reflects fluctuations in palaeodischarge, probably related to climatic variation. The main cycles are approximately 130 m thick; spectral analysis reveals two further strong periodicities at approximately 36 and 55 m. Estimated sediment accumulation rates suggest that the cycles represent periods of the order of lo⁴ years. It is proposed that the longer cycles reflect the 412,000 yr orbital eccentricity cycle and that the shorter cycles are either harmonics or components of the 100,000 yr eccentricity cycle.     

Comparison of laplace transform and finite difference solutions for an evolving permafrost region

Laplace transform solutions are derived for an evolving permafrost region in saturated ground when the freezing interface moves with constant speed. The solution is inverse in the sense that the melting temperature at the interface and the groud surface temperature are prescribed functions of time. The solution procedure incorporates an initial temperature distribution in a domain extended above the ground surface. This allows, by asymptotic analysis, the construction of initially continuous melting and surface temperatures with bounded first and second derivatives. Solutions for two classes of initial conditions are determined by numerical inversion of the transforms. These solutions are used to test the corresponding solutions obtained by a direct finite difference algorithm developed earlier.¹ Good agreements for both interface path and temperature profiles are obtained in both classes.     

Meridional transport of HCN from SL9 impacts on Jupiter

In July 1994, the Shoemaker-Levy 9 (SL9) impacts introduced hydrogen cyanide (HCN) to Jupiter at a well confined latitude band around −44°, over a range of specific longitudes corresponding to each of the 21 fragments (Bézard et al. 1997, Icarus 125, 94-120). This newcomer to Jupiter's stratosphere traces jovian dynamics. HCN rapidly mixed with longitude, so that observations recorded later than several months after impact witnessed primarily the meridional transport of HCN north and south of the impact latitude band. We report spatially resolved spectroscopy of HCN emission 10 months and 6 years following the impacts. We detect a total mass of HCN in Jupiter's stratosphere of 1.5±0.7×10¹³ g in 1995 and 1.7±0.4×10¹³ g in 2000, comparable to that observed several days following the impacts (Bézard et al. 1997, Icarus 125, 94-120). In 1995, 10 months after impact, HCN spread to −30° and −65° latitude (half column masses), consistent with a horizontal eddy diffusion coefficient of K_yy=2-3×10¹⁰ cm² s⁻¹. Six years following impact HCN is observed in the northern hemisphere, while still being concentrated at 44° south latitude. Our meridional distribution of HCN suggests that mixing occurred rapidly north of the equator, with K_yy=2-5×10¹¹ cm² s⁻¹, consistent with the findings of Moreno et al. (2003, Planet. Space Sci. 51, 591-611) and Lellouch et al. (2002, Icarus 159, 112-131). These inferred eddy diffusion coefficients for Jupiter's stratosphere at 0.1-0.5 mbar generally exceed those that characterize transport on Earth. The low abundance of HCN detected at high latitudes suggests that, like on Earth, polar regions are dynamically isolated from lower latitudes.     

Hydrogen atom in intense magnetic field

The structure of a hydrogen atom situated in an intense magnetic field is investigated. Three approaches are employed. An elementary Bohr picture establishes a crucial magnetic field strength,H _a ?5×10⁹G. Fields in excess ofH _a are intense in that they are able to modify the characteristic atomic scales of length and binding energy. A second approach solves the Schrödinger equation by a combination of variational methods and perturbation theory. It yields analytic expressions for the wave functions and energy eigenvalues. A third approach determines the energy eigenvalues by reducing the Schrödinger equation to a one-dimensional wave equation, which is then solved numerically. Energy eigenvalues are tabulated for field strengths of 2×10¹⁰G and 2×10¹² G. It is found that at 2×10¹² G the lowest energy eigenvalue is changed from ?13.6 eV to about ?180 eV in agreement with previous variational computations.     

Solar flares in the EUV observed from OSO-5

Solar flares in three broad EUV spectral bands have been observed from OSO-5 with a grating spectrophotometer. Results are given for three large flares of March 12, March 21 and April 21, 1969. In general the time dependence of flare intensity in each band is characterized by a slowly varying component with impulsive bursts superimposed. Bands 2 (465–630 Å) and 3 (760–1030 Å) are quite similar in their time variations, but band 1 (280–370 Å) shows less impulsive structure, and declines more slowly. Absolute EUV intensities for the flares are estimated, and a comparison made with the 2800 mc s^–1 radio emission. A flare model is proposed to account for the EUV time variations during a large flare.     

Integrated measurements of acoustical and optical thin layers II: Horizontal length scales

The degree of layered organization of planktonic organisms in coastal systems impacts trophic interactions, the vertical availability of nutrients, and many biological rate processes. While there is reasonable characterization of the vertical structure of these phenomena, the extent and horizontal length scale of variation has rarely been addressed. Here we extend the examination of the vertical scale in the first paper of the series to the horizontal scale with combined shipboard acoustic measurements and bio-optic measurements taken on an autonomous underwater vehicle. Measurements were made in Monterey Bay, CA from 2002 to 2008 for the bio-optical parameters and during 2006 for acoustic scattering measurements. The combined data set was used to evaluate the horizontal decorrelation length scales of the bio-optical and acoustic scattering layers themselves. Because biological layers are often decoupled from the physical structure of the water column, assessment of the variance within identified layers was appropriate. This differs from other studies in that physical parameters were not used as a basis for the layer definition. There was a significant diel pattern to the decorrelation length scale for acoustic layers with the more abundant nighttime layers showing less horizontal variability despite their smaller horizontal extent. A significant decrease in the decorrelation length scale was found in bio-optical parameters over six years of study, coinciding with a documented shift in the plankton community. Results highlight the importance of considering plankton behavior and time of day with respect to scale when studying layers, and the challenges of sampling these phenomena.     

Unraveling the sequence and structure of the protein osteocalcin from a 42 ka fossil horse

We report the first complete amino acid sequence and evidence of secondary structure for osteocalcin from a temperate fossil. The osteocalcin derives from a 42 ka equid bone excavated from Juniper Cave, Wyoming. Results were determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-MS) and Edman sequencing with independent confirmation of the sequence in two laboratories. The ancient sequence was compared to that of three modern taxa: horse (Equus caballus), zebra (Equus grevyi), and donkey (Equus asinus). Although there was no difference in sequence among modern taxa, MALDI-MS and Edman sequencing show that residues 48 and 49 of our modern horse are Thr, Ala rather than Pro, Val as previously reported (Carstanjen B., Wattiez, R., Armory, H., Lepage, O.M., Remy, B., 2002. Isolation and characterization of equine osteocalcin. Ann. Med. Vet.146(1), 31-38). MALDI-MS and Edman sequencing data indicate that the osteocalcin sequence of the 42 ka fossil is similar to that of modern horse. Previously inaccessible structural attributes for ancient osteocalcin were observed. Glu₃₉ rather than Gln₃₉ is consistent with deamidation, a process known to occur during fossilization and aging. Two post-translational modifications were documented: Hyp₉ and a disulfide bridge. The latter suggests at least partial retention of secondary structure. As has been done for ancient DNA research, we recommend standards for preparation and criteria for authenticating results of ancient protein sequencing.     

Fluctuations of local glaciers in Greenland during latest Pleistocene and Holocene time

This paper is the first to summarize research on fluctuations of local glaciers in Greenland (e.g. ice caps and mountain glaciers independent of the Greenland Ice Sheet) during latest Pleistocene and Holocene time. In contrast to the extensive data available for fluctuations of the Greenland Ice Sheet, surprisingly little data exist to constrain local glacier extents. Much of the available research was conducted prior to wide-spread use of AMS radiocarbon dating and the advent of surface-exposure and luminescence dating. Although there is a paucity of data, generally similar patterns of local glacier fluctuations are observed in all regions of Greenland and likely reflect changes in paleoclimate, which must have influenced at least the margins of the Inland Ice. Absolute-age data for late-glacial and early Holocene advances of local glaciers are reported from only two locations: Disko (island) and the Scoresby Sund region. Subsequent to late-glacial or early Holocene time, most local glaciers were smaller than at present or may have disappeared completely during the Holocene Thermal Maximum. In general, local glacier advances that occurred during Historical time (1200–1940 AD) are the most extensive since late-glacial or early Holocene time. Historical documents and more recent aerial photographs provide useful information about local glacier fluctuations during the last 100 yrs. In all but one area (North Greenland), local glaciers are currently receding from Historical extents.     

An X-ray absorption spectroscopy study of Cd binding onto bacterial consortia

In this study, we use extended X-ray absorption fine structure (EXAFS) spectroscopy measurements to examine the atomic environment of Cd bound onto two experimental bacterial consortia: one grown from river water, and one grown from a manufacturing gas plant site. The experiments were conducted as a function of pH and demonstrate that the complex mixtures of bacteria, containing both Gram-positive and Gram-negative species, yield relatively simple EXAFS spectra, a result which indicates that only a limited number of functional group types contribute to Cd binding for each bacterial consortium. The EXAFS spectra indicate that the average Cd binding environment in the river water consortium varies significantly with pH, but the manufacturing gas plant consortium exhibits a Cd binding environment that remains relatively constant over the pH range examined. The EXAFS data for the river water consortium were modeled using carboxyl, phosphoryl and sulfhydryl sites. However, only carboxyl and phosphoryl sites were required to model the manufacturing gas plant consortium data under similar experimental conditions. This is the first EXAFS study to identify and quantify the relative importance of metal binding sites in bacterial consortia. Although our results indicate differences in the binding environments of the two consortia, the data suggest that there are broad similarities in the binding environments present on a wide range of bacterial cell walls.