Karst unit mapping using geographic information system technology,Mower County,Minnesota, USA

Mower County is in southeastern Minnesota in an area underlain by sedimentary bedrock. These rocks are karsted Middle Devonian and Middle Ordovician limestone and dolomite. The karst features of the county were inventoried. These features include sinkholes, disappearing streams, caves, dry valleys, and springs. Previous karst mapping efforts for other counties in Minnesota have produced sinkhole probability maps and a springshed map. In Mower County, we have developed a new type of karst map using a geographic information system (GIS) to produce a karst unit map. Karst units are discrete three-dimensional bodies in which solution of the bedrock has resulted in the integration of surface water and groundwater. The field mapping and hydrologic investigations were done with conventional methods. The karst unit delineation was done using GIS technology, which allowed us to examine the county's karst using two-dimensional and three-dimensional views. Many different overlays of the karst elements were combined to better understand the landscape dynamics. Ultimately, it was the overlay of the karst features, hydrologic information, and depth-to-bedrock mapping on a shaded relief landscape morphology map which allowed us to best delineate the individual karst units.     

Scots Pine Growth Trends in Northwestern Kola Peninsula as an Indicator of Positive Changes in the Carbon Cycle

Growth trends of Scots pine (Pinus sylvestris) at its northernmost extent may be an indicator of changes in the carbon cycle of terrestrial forest ecosystems. Using a method which removed age trends from the data, a time-series analysis of annual radial increment in wood over the last few decades compared with the period of the last registered warming (maximum around 1930–40), revealed elevated growth of 78% for trees 0–20 years old, 56% for trees 21–40 years old, 21% for trees 41–60 years old, and 10% for trees more than 101 years old. Increments of trees in the61–80 and 81–100 years old age classes from the two periods were similar. The higher rate of growth in recent times occurred despite a decrease in temperature after about 1940 and significant air pollution. During the last century growth of Scots pine increased for trees in all age groups, except for trees in the 81–100 year old age class for which it was constant. The average rates of growth were estimated at 0.016 mm/year for trees in the 0–20 year age class, 0.012 mm/year for the 21–40 year age class, 0.005 mm/year for the 41–60 year age class, 0.008 mm/year for the 61–80 year age class and 0.006 mm/year for trees in the greater than 101 year age class. The growth trends were unstable over time and took place concurrent with increasing oscillations in radial increment. The most probable reasons for the marked increase in radial increment growth of Scots pine in this region are climate warming and higher levels of carbon dioxide. Together these may produce a synergistic effect on growth.     

Pyroclastic surges and flows from the 8–10 May 1997 explosive eruption of Bezymianny volcano, Kamchatka, Russia

The 8-10 May 1997 eruption of Bezymianny volcano began with extrusion of a crystallized plug from the vent in the upper part of the dome. Progressive gravitational collapses of the plug caused decompression of highly crystalline magma in the upper conduit, leading at 13:12 local time on 9 May to a powerful, vertical Vulcanian explosion. The dense pyroclastic mixture collapsed in boil-over style to generate a pyroclastic surge which was focused toward the southeast by the steep-walled, 1956 horseshoe-shaped crater. This surge, with a temperature <200 °C, covered an elliptical area >30 km² with deposits as much as 30 cm thick and extending 7 km from the vent. The surge deposits comprised massive to vaguely laminated, gravelly sand (Md -1.2 to 3.7J sorting 1.2 to 3J) of poorly vesiculated andesite (mean density 1.82 g cm^-3; vesicularity 30 vol%; SiO₂ content ~58.0 wt%). The deposits, with a volume of 5-15᎒⁶ m³, became finer grained and better sorted with distance; the maximal diameter of juvenile clasts decreased from 46 to 4 cm. The transport and deposition of the surge over a snowy landscape generated extensive lahars which traveled >30 km. Immediately following the surge, semi-vesiculated block-and-ash flows were emplaced as far as 4.7 km from the vent. Over time the juvenile lava in clasts of these flows became progressively less crystallized, apparently more silicic (59.0 to 59.9 wt% SiO₂) and more vesiculated (density 1.64 to 1.12 g cm^-3; vesicularity 37 to 57 vol%). At this stage the eruption showed transitional behavior, with mass divided between collapsing fountain and buoyant column. The youngest pumice-and-ash flows were accompanied by a sustained sub-Plinian eruption column ~14 km high, from which platy fallout clasts were deposited (~59.7% SiO₂; density 1.09 g cm^-3; vesicularity 58 vol%). The explosive activity lasted about 37 min and produced a total of ~0.026 km³ dense rock equivalent of magma, with an average discharge of ~1.2᎒⁴ m³ s^-1. A lava flow ~200 m long terminated the eruption. The evolutionary succession of different eruptive styles during the explosive eruption was caused by vertical gradients in crystallization and volatile content of the conduit magma, which produced significant changes in the properties of the erupting mixture.     

Dead shrub patches as ecosystem engineers in degraded drylands

A long-term drought has led to the mass mortality of shrubs in the semi-arid Israeli Negev.The most impacted shrub species is the Noaea mucronata (Forssk.) Asch.and Schweinf.In a four-year study,we found that herbaceous vegetation growth was greater in the dead shrub patches than in the surrounding inter-patch biocrusted spaces,suggesting that the dead shrub patches encompass improved micro-habitats.However,unexpectedly,the soil moisture in the dead shrub patches was consistently lower than that of the inter-patch biocrusted spaces.At the same time,soil quality in the dead shrub patches was higher than that in the inter-patch spaces.Therefore,it seems that the overall better soil conditions in the dead patches overcome the scarcity of soil-water,supporting increased herbaceous produc-tivity.For explaining the discrepancy between herbaceous vegetation and soil-water,we formulated a conceptual framework,which highlights the key factors that regulate soil-water dynamics in this dryland ecosystem.We demonstrate that herbaceous vegetation is facilitated in the dead shrub patches by a legacy effect that takes place long after the shrubs have died.The dead shrub patches encompass a unique form of ecosystem engineering.The study high-lights the complex and unpredicted impacts of prolonged droughts on dryland ecosystems.     

Use of non-linear localization for isolating structures from earthquake-induced motions

The dynamic response due to earthquake-induced excitations of multi-storey buildings simulated by a cantilever (with attached concentrated masses) supported on a flexible foundation, is reconsidered when stiffness non-linearities are included. To this end, a suitable non-linear spring-mass device is placed between the ground and the mass of the foundation, which under certain conditions can absorb a significant amount of seismic energy over a large frequency range, thus drastically reducing the seismic response of the foundation. This is achieved by the stiffness non-linearity that gives rise to a localization phenomenon, according to which motions generated by external disturbances remain passively localized close to the point of seismic excitation instead of ‘spreading’ to the entire structure. The implications of these findings to the design of earthquake-resistant structures are discusssed. Copyright © 1999 John Wiley & Sons, Ltd.     

Analytical prediction of seismic behaviour for concentrically-braced steel systems

This paper presents an analytical model for the inelastic response analysis of braced steel structures. A model is first presented for the behaviour of steel struts subjected to cyclic axial load, which combines the analytical formulation of plastic hinge behaviour with empirical formulas developed on the basis of experimental data. The brace is modelled as a pin-ended member, with a plastic hinge located at the midspan. Braces, with other end conditions, are handled using the effective length concept. Step-wise regression analysis is employed, to approximate the plastic conditions for the steel UC section. Verification of the brace model is performed on the basis of quasi-static analyses of individual struts and a one-bay one-storey X-braced steel frame. The comparison of analytical and experimental data has confirmed that the proposed brace model is able to accurately simulate the cyclic inelastic behaviour of steel braces and braced systems. A series of dynamic analyses has been performed on two-storey V- and X-braced frames to study the influence of brace slenderness ratio on the inelastic response, and to look at the redistribution of forces in the post-buckling range of behaviour of CBFs. Recommendations have been made as to the estimation of maximum storey drifts for concentrically-braced steel frames in major seismic event. © 1997 John Wiley & Sons, Ltd.     

Vitellogenin in the blood plasma of male cod (Gadus morhua): a sign of oestrogenic endocrine disruption in the open sea?

An ELISA for cod vitellogenin (VTG) has been set up using cod lipovitellin for plate coating and standardisation. The assay has been applied to plasma samples collected from male and female cod caught in three distinct areas around the UK, three areas off the Norwegian coast and also to cod reared initially at an aquaculture site and subsequently maintained at a research station. The aim of the study was to determine whether there were any signs of oestrogenic endocrine disruption in a fish species living offshore. VTG induction was found in male cod caught in the North Sea, the Shetland Box area, in Oslofjord and also in cultivated fish. There was a strong relationship between concentrations of VTG and fish size. There was no evidence that the presence of VTG in the plasma of males is a natural part of their life cycle. On the other hand, the size of fish at which these elevated VTG concentrations appear (ca. 5 kg) is about the size that cod change from feeding primarily on benthic invertebrates to mainly other fish, both benthic and pelagic. The possibility is suggested that large cod pick up oestrogenic endocrine disrupters through the food chain.     

Automated placement of supplementary contour lines

Supplementary contour lines are placed between regular contour lines to visualize small but important forms that regular contour lines are unable to show. On topographic maps, typical forms are hillcrests, depressions, saddles, terraces, banks, and levees. No automated method for the selection of supplementary contour lines has been described so far. We document cartographic design principles for the selection of supplementary contour lines for topographic maps, and present an automated method for their placement. Results of the automated method are similar to manually placed supplementary contour lines. Our method helps map authors to create contour line maps that more effectively illustrate relevant small details in maps showing terrain elevation or other scalar fields.     

Carbonaceous matter in the Sariçiçek meteorite

As of today, the Sariçiçek (SC) meteorite is the newest howardite and the only confirmed fall among the 17 known howardites. In this study, we present isotopic, infrared, and Raman data on three distinct pieces of the SC meteorite. Our oxygen isotopic measurements show that Δ¹⁷O values of the pieces are close to each other, and are in good agreement with other howardites, eucrites, and diogenites. The carbon isotopic measurements, which were conducted by combusting terrestrial contamination selectively at temperatures lower than 500–600 °C, show the presence of indigenous carbon in the SC specimens. The matrix of these specimens, investigated via infrared microspectroscopy, appears to be dominated by clinopyroxene/orthopyroxene, forsterite, and fayalite, with minor contributions from ilmenite, plagioclase, and enstatite. Carbon‐rich regions were mapped and studied via Raman imaging microspectroscopy, which reveals that both amorphous and graphitic carbon exist in these samples. Synchrotron‐based infrared microspectroscopy data show the presence of very little aliphatic and aromatic hydrocarbons. The SC meteorite is suggested to be originating from the Antonia impact crater in the Rheasilvia impact basin on 4 Vesta (Unsalan et al. 2019). If this is in fact the case, then the carbon phases present in the SC samples might provide clues regarding the impactor material (e.g., carbonaceous chondrites).     

The CM carbonaceous chondrite regolith Diepenveen

A carbonaceous chondrite was recovered immediately after the fall near the village of Diepenveen in the Netherlands on October 27, 1873, but came to light only in 2012. Analysis of sodium and poly‐aromatic hydrocarbon content suggests little contamination from handling. Diepenveen is a regolith breccia with an overall petrology consistent with a CM classification. Unlike most other CM chondrites, the bulk oxygen isotopes are extremely ¹⁶O rich, apparently dominated by the signature of anhydrous minerals, distributed on a steep slope pointing to the domain of intrinsic CM water. A small subset plots closer to the normal CM regime, on a parallel line 2 ‰ lower in δ¹⁷O. Different lithologies in Diepenveen experienced varying levels of aqueous alteration processing, being less aqueously altered at places rather than more heated. The presence of an agglutinate grain and the properties of methanol‐soluble organic compounds point to active impact processing of some of the clasts. Diepenveen belongs to a CM clan with ~5 Ma CRE age, longer than most other CM chondrites, and has a relatively young K‐Ar resetting age of ~1.5 Ga. As a CM chondrite, Diepenveen may be representative of samples soon to be returned from the surface of asteroid (162173) Ryugu by the Hayabusa2 spacecraft.