Magnetic polarity stratigraphy of the Upper Siwalik deposits,Pabbi Hills,Pakistan

Over 1000 m of fluvial molasse, exhibiting a stable detrital remanent magnetization, is exposed in a mammal-bearing sequence in the Upper Siwalik Group of the Pabbi Hills, Pakistan. The magnetic polarity chronology reveals that the sequence records a time period of 2.6 m.y., extending from the early Gauss Normal Epoch into the Brunhes Normal Epoch. During this period, sedimentation rates increased upward in time from 0.25 m/1000 yr to 0.45 m/1000 yr. The sudden disappearance of red beds and a change in the lithoclastic composition of basal channel sands suggests that about 800,000 years ago the primary source area began shifting from the metamorphic terrane of the Himalayan Orogen to a more local sedimentary terrane on the folded margins of the Himalayan foredeep. About 500,000 years ago the anticlinal Pabbi Hills attained surface expression. Uplift continued at a minimum rate of 1 m/1000 yr.A local Pliocene/Pleistocene boundary based on the Olduvai Normal Event is clearly recognized. Local fossil finds reveal thatEquus, diagnostic element of the Pinjor faunal zone, appeared locally about 1.8 m.y. ago and thatHipparion, a faunal element of the Tatrot and earlier faunal zones, persisted locally until at least 3.0 m.y. ago.     

Die Matrix der Fische XVI Zweidimensionale papierchromatographische Analyse von Fischschuppenhydrolysaten und Hydrolysaten einiger weiterer Fischorgane

Summary The aminoacids in hydrolysates (HCl) of the scales of six different fish-species have been determined by partition paper chromatography (Consden andDent). The scales contain considerable amounts of protein besides hydroxyl apatit and guanin, but none or only minute quantities of carbohydrates. Some of the aminoacids in the liver, air-bladder, kidney and the body muscles of two fish species were investigated.      

Monitoring persistent organic pollutants in leatherback turtles (Dermochelys coriacea) confirms maternal transfer

To assess threats to endangered species, it is critical to establish baselines for contaminant concentrations that may have detrimental consequences to individuals or populations. We measured contaminants in blubber and fat from dead leatherback turtles and established baselines in blood and eggs in nesting turtles. In fat, blubber, blood and eggs, the predominant PCBs were 153 + 132, 187 + 182, 138 + 163, 118, and 180 + 193. Total PCBs, 4,4′-DDE, total PBDEs and total chlordanes were significantly and positively correlated between blood and eggs, suggesting maternal transfer. Significant positive relationships also existed between fat and blubber in stranded leatherbacks. Less lipophilic PCBs appeared to more readily transfer from females to their eggs. PBDE profiles in the four tissues were similar to other wildlife populations but different from some turtle studies. Concentrations were lower than those shown to have acute toxic effects in other aquatic reptiles, but may have sub-lethal effects on hatchling body condition and health.     

Variation of sediment geotechnical properties between the greater antilles outer ridge and the nares abyssal plain

Abstract

It is clear from morphology alone that distinctly different dynamic and sedimentary processes can be expected to be associated with the Greater Antilles Outer Ridge relative to those of the adjacent Nares Abyssal Plain. This difference is further substantiated by seismic reflection data which show the ridge to be a very large prism of acoustically transparent sediment in contrast to the stratified deposits of the abyssal plain. An examination of the geotechnical properties of the near‐surface (0 to 2.4m) deposits of the two areas also reveals distinct differences in their sedimentological characteristics. The outer ridge sediments, of more or less homogenous clay‐size material, display much higher water contents, porosities, sensitivities, plasticity, and organic carbon contents in contrast to the abyssal plain deposits which are much less homogenous owing to the presence of turbidite sequences. The turbidites themselves are uniquely contrasted to the other abyssal plain sediments by their higher silt content, wet bulk density, shear strength, and sensitivity.     

The cratering history of asteroid (2867) Steins

The cratering history of main belt asteroid (2867) Steins has been investigated using OSIRIS imagery acquired during the Rosetta flyby that took place on the 5th of September 2008. For this purpose, we applied current models describing the formation and evolution of main belt asteroids, that provide the rate and velocity distributions of impactors. These models coupled with appropriate crater scaling laws, allow the cratering history to be estimated. Hence, we derive Steins’ cratering retention age, namely the time lapsed since its formation or global surface reset. We also investigate the influence of various factors—like bulk structure and crater erasing—on the estimated age, which spans from a few hundred Myrs to more than 1 Gyr, depending on the adopted scaling law and asteroid physical parameters. Moreover, a marked lack of craters smaller than about 0.6 km has been found and interpreted as a result of a peculiar evolution of Steins cratering record, possibly related either to the formation of the 2.1 km wide impact crater near the south pole or to YORP reshaping.     

Learning and climate change

Abstract

Learning—i.e. the acquisition of new information that leads to changes in our assessment of uncertainty—plays a prominent role in the international climate policy debate. For example, the view that we should postpone actions until we know more continues to be influential. The latest work on learning and climate change includes new theoretical models, better informed simulations of how learning affects the optimal timing of emissions reductions, analyses of how new information could affect the prospects for reaching and maintaining political agreements and for adapting to climate change, and explorations of how learning could lead us astray rather than closer to the truth. Despite the diversity of this new work, a clear consensus on a central point is that the prospect of learning does not support the postponement of emissions reductions today.     

Semi-empirical solar line blanketing

Statistical data for line blanketing in the solar atmosphere have been extracted from the Revised Rowland Table. The data are corrected for apparent observational incompleteness due to line crowding and blending and are placed in a convenient form for calculations. An attempt is made to interpret the data in terms of schematic representations of the energy levels and distribution of gf-values for the important absorbers. The analysis leads to predictions in good agreement with the forms of the statistical data and substantiates the assumption of observational incompleteness in the original data. The analysis suggests that the solar data may provide useful guidance in the blanketing of stellar atmospheres sufficiently close to solar type.A blanketing method is presented which makes use of a uniformly-smeared-line (single picket) procedure and which assumes LTE and a weak-line curve of growth. The blanketing coefficient is obtained in a simple manner from the corrected statistical data and is both depth and wavelength dependent. An alternative method utilizing a four-picket scheme and average absorption coefficient profiles is suggested. Comparison of solar models computed by the two methods shows good agreement and gives support for the smeared-line procedure. Comparison of the solar model with a non-LTE blanketed model of Athay also shows reasonable agreement.Publications of the Goethe Link Observatory, Indiana University, No. 110.     

Seasonal Variability of Adsorption and Exchange Equilibria in Soil Waters

Chemical analyses for major ions have been conducted on waters,collected on an approximately weekly basis over the period April, 1993 toNovember, 1996, that drain three small experimental ecosystems(sandboxes) at Hubbard Brook, New Hampshire. One sandbox is planted withpine trees, another with grass, and the third is left bare (actually itis covered sporadically by bryophytes and lichens). Results show linearcorrelations, independent of discharge, between the concentrations ofdissolved Na⁺ and K⁺ on the one hand andCa⁺⁺ and Mg⁺⁺ on the other for all threesandboxes. No correlations between singly charged and doubly chargedcations were found. These correlations are interpreted to represent cationexchange equilibria between soil waters and clay minerals plus soil organicmatter. The correlation slope, representing the exchange constant, for Na vsK is different for the pine-covered sandbox than for the other two whereasfor Ca vs Mg the correlation is independent of the presence or absence oftrees. We interpret this as representing a shift of cation exchangeequilibria in the pine sandbox by the activities of growing trees.Concentrations of Na, K, Ca, Mg, and H₄SiO₄from the barren and grass-lined sandboxes were found to vary seasonally witha marked sinusoidal pattern which was independent of the discharge from eachsandbox. (The discernment of a similar pattern in the tree lined sandbox wasdifficult due to a lack of discharge over much of the year.) Concentrationmaxima occurred in August and minima in February, and there is a closeparallelism with soil temperature. We interpret this as representingtemperature induced variations in cation exchange equilibria and silicaadsorption. Independence from highly varying water discharge, e.g.,. thataccompanying severe rainstorms, indicates rapidly re-attained equilibrium.Variations in the concentrations of cations are likely due to exchange withunmeasured cations, probably H⁺ or dissolved Al species, as aresult of possible seasonal changes in internal acid production and externalinput of acid rain to the sandboxes. Internal production may represent aresponse to seasonal changes in respiration rate as it responds toseasonally varying temperature. Added to this is the effect of temperatureon exchange equilibrium. Seasonal variations in dissolved silica are mostlikely due to the dependence of adsorption/desorption equilibria ontemperature. The temperature dependence of a number of silica-consumingreactions are consistent with the measured values.