GARSTEC—the Garching Stellar Evolution Code     

Achim Weiss  Helmut Schlattl 《Astrophysics and Space Science》2008,316(1-4):99-106

We describe the Garching Stellar Evolution Code. General features, treatment of the microphysics, details of the numerical solution, handling and particularities are discussed. The standard solar model serves as the most basic benchmark to test the accurateness of the code and is presented, too.  相似文献   

Some observations on diamondiferous bedrock gully trapsites on Late Cainozoic, marine-cut platforms of the Sperrgebiet, Namibia     

J. Jacob  J.D. Ward  B.J. Bluck  R.A. Scholz  H.E. Frimmel 《Ore Geology Reviews》2006,28(4):493

Namibia's southwestern coast, the Sperrgebiet, hosts one of the world's largest gem diamond placer deposits consisting of fluvial, marine and desert deflation/aeolian placer types. To date, the richest onshore placer discovered in the Sperrgebiet comprises several, Plio-Pleistocene to Holocene, littoral marine packages distributed northwards from the Orange River mouth for some 120 km to Chameis Bay. In this zone, known as Mining Area No. 1 (MA1), these Quaternary marine deposits are floored predominantly by siliciclastic rocks of the Late Proterozoic Gariep Belt that have been bevelled into a number of marine-cut platforms during the different Quaternary high sea level stands (notably, at + 30 m, + 8 m, + 4 m and + 2 m). In many places, these bedrock platforms are extensively gullied and potholed, forming abundant fixed trapsites that promote diamond concentration in the Late Cainozoic littoral sediments. Some observations on the distribution, orientation and incision of bedrock gullies in MA1 are presented here.Three principal bedrock gully types, all of which constitute good diamond trapsites, have been identified in the bedrock footwall between the Orange River mouth northwards to Chameis Bay, a distance of some 120 km: (i) swash-parallel gullies in the southern, proximal sector where the bedrock s₂ dips 45°W and the abrasive gravels are most abundant, thus overriding lithological and structural controls in the footwall; (ii) strike-parallel gullies in the central reach where the bedrock s₂ dips between 80° and 85°W and the abrasive bedload is reduced, resistant lithological units promote the formation of such features along the orientation of the metsediments; and (iii) joint gullies in the northern, distal portion where the bedrock s₂ dips 45–60° to the E and coarse abrasive bedload is virtually absent, the structural pattern in the bedrock is exploited by marine erosion.In these Late Cainozoic placers, diamond concentration is further linked to the depth of the gullies incised into the marine-cut platforms. Maximum incision is noted on the seaward margins of the marine-cut platforms where high-energy littoral processes, acting in a micro-tidal range of ca. 1.8 m under strong prevailing southerly wind and South Atlantic derived southwesterly swell regimes, promote marine erosion and deep gully formation.Therefore, the most favourable diamondiferous trapsites in the Late Cainozoic marine packages of the southwestern Sperrgebiet are those developed in deep bedrock gullies of either swash-parallel, strike-parallel or joint pattern origin on the seaward margins of marine-cut platforms that represent discrete high sea level stands during the Quaternary.  相似文献   

A large skull of Ichthyosaurus (Reptilia: Ichthyosauria) from the Lower Sinemurian (Lower Jurassic) of Frick (NW Switzerland)     

Michael W. Maisch  Achim G. Reisdorf  Rudolf Schlatter  Andreas Wetzel 《Swiss Journal of Geoscience》2008,101(3):617-627

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The bridgman ring paradox revisited     

C. H. Scholz  G. Boitnott  S. Nemat-Nasser 《Pure and Applied Geophysics》1986,124(3):587-599

The Bridgman ring experiment, in which a hard rubber ring slipped over a steel rod was observed to split when subjected to a hydrostatic confining pressure, was repeated with Pyrex glass rings. Three cases were studied, in which (a) both ring and rod were unjacketed, (b) the inner wall of the ring was sealed from the pressure medium and (c) both rod and ring were completely jacketed. In the first two cases the ring was observed to split abruptly, with a single axial crack when confining pressure reached a critical level. In the third case no abrupt failure occurred, but a number of axial cracks were found to have formed, grown stably, but not penetrated the outer wall of the ring. The first two cases are explained by hydraulic fracturing of the ring. Observations and analysis indicate that in the third case the cracks started at flaws on the inner surface of the ring and propagated outwards in a stable manner. This case, in which a tensile crack propagates in an all-around compressive stress field, provides some insight into axial cracking of rock in triaxial compression and tensile failure of rock under radial shock loading.  相似文献   

Recent ecological responses to climate variability and human impacts in the Nianbaoyeze Mountains (eastern Tibetan Plateau) inferred from pollen,diatom and tree-ring data   总被引：1，自引：0，他引：1  

Juliane Wischnewski  Ulrike Herzschuh  Kathleen M. Rühland  Achim Bräuning  Steffen Mischke  John P. Smol  Lily Wang 《Journal of Paleolimnology》2014,51(2):287-302

The Tibetan Plateau is a region that is highly sensitive to recent global warming, but the complexity and heterogeneity of its mountainous landscape can result in variable responses. In addition, the scarcity and brevity of regional instrumental and palaeoecological records still hamper our understanding of past and present patterns of environmental change. To investigate how the remote, high-alpine environments of the Nianbaoyeze Mountains, eastern Tibetan Plateau, are affected by climate change and human activity over the last ~600 years, we compared regional tree-ring studies with pollen and diatom remains archived in the dated sediments of Dongerwuka Lake (33.22°N, 101.12°E, 4,307 m a.s.l.). In agreement with previous studies from the eastern Tibetan Plateau, a strong coherence between our two juniper-based tree-ring chronologies from the Nianbaoyeze and the Anemaqin Mountains was observed, with pronounced cyclical variations in summer temperature reconstructions. A positive directional trend to warmer summer temperatures in the most recent decades, was, however, not observed in the tree-ring record. Likewise, our pollen and diatom spectra showed minimal change over the investigated time period. Although modest, the most notable change in the diatom relative abundances was a subtle decrease in the dominant planktonic Cyclotella ocellata and a concurrent increase in small, benthic fragilarioid taxa in the ~1820s, suggesting higher ecosystem variability. The pollen record subtly indicates three periods of increased cattle grazing activity (~1400–1480 AD, ~1630–1760 AD, after 1850 AD), but shows generally no significant vegetation changes during past ~600 years. The minimal changes observed in the tree-ring, diatom and pollen records are consistent with the presence of localised cooling centres that are evident in instrumental and tree-ring data within the southeastern and eastern Tibetan Plateau. Given the minor changes in regional temperature records, our complacent palaeoecological profiles suggest that climatically induced ecological thresholds have not yet been crossed in the Nianbaoyeze Mountains region.  相似文献   

Astrometrische Verwendung der zweiten kurzen Exposition auf Tautenburger Pilotprogrammplatten     

R.-D. Scholz 《Astronomische Nachrichten》1987,308(6):375-378

To overcome a possible magnitude equation the Tautenburg Schmidt plates of the Lohrmann programme were taken with a long 20-minute exposure (System A) and a short 20-second exposure (System C) displaced about 0·5 minute of arc in declination from the long exposure. The distance between the two images in dependence on the magnitude of a star and its position on the plate was analysed. The transformation of coordinates from system C to A can be performed by using first order polynomials. No higher order terms were found to be necessary. The coefficients of the polynomials can not be assumed as constant for all plates but must be computed from least squares solutions involving a sufficient number of stars on each plate. For three of four plates investigated significant orthogonal linear terms were detected.  相似文献   

Insights into Holocene relative sea-level changes in the southern North Sea using an improved microfauna-based transfer function     

Juliane Scheder  Friederike Bungenstock  Kristin Haynert  Anna Pint  Frank Schlütz  Peter Frenzel  Achim Wehrmann  Helmut Brückner  Max Engel 《第四纪科学杂志》2022,37(1):71-85

In light of global warming and rising relative sea level (RSL), detailed reconstructions of RSL histories and their controlling processes are essential in order to manage coastal-protection challenges. This study contributes to unravelling Holocene RSL change on the East Frisian North Sea coast in high resolution and with a new approach for the German Bight. For the first time, a transfer function (vertical error: 29.7 cm ? ~11% of the mean tidal range) for RSL change based on a combined training set of benthic foraminifers and ostracods from the back-barrier tidal basin of Spiekeroog is applied to the Holocene record of the back-barrier tidal basin of Norderney. The resulting RSL curve for the Norderney tidal basin is corrected for decompaction and shows a deceleration in RSL rise between 6000 and 5000 cal bp. The smallest possible error envelope (~1 m) results from the good suitability of salt-marsh layers between 5000 and 4000 cal bp. The RSL curve provides an approach towards the closure of the common data gap of peat-based curves for the southern North Sea related to a lack of basal peats in the youngest age range, and verifies regional differences in glacial isostatic adjustment.  相似文献   

Astrophysical supplements to the ASCC‐2.5. II. Membership probabilities in 520 Galactic open cluster sky areas     

N. V. Kharchenko  A. E. Piskunov  S. Rser  E. Schilbach  R.‐D. Scholz 《Astronomische Nachrichten》2004,325(9):740-748

We present a catalogue (CSOCA) of stars residing in 520 Galactic open cluster sky areas which is the result of the kinematic (proper motion) and photometric member selection of stars listed in the homogeneous All‐sky Compiled Catalogue of 2.5Million Stars (ASCC‐2.5).We describe the structure and contents of the catalogue, the selection procedure applied, and the proper motion and photometric membership constraints adopted. In every cluster area the CSOCA contains the complete list of the ASCC‐2.5 stars regardless of their membership probability. For every star the CSOCA includes accurate J2000 equatorial coordinates, proper motions in the Hipparcos system, BV photometric data in the Johnson system, proper motion and photometric membership probabilities, as well as angular distances from the cluster centers for about 166 000 ASCC‐2.5 stars. If available, trigonometric parallaxes, spectral types, multiplicity and variability flags from the ASCC‐2.5, and radial velocities with their errors from the Catalogue of Radial Velocities of Galactic Stars with high precision Astrometric Data (CRVAD) are also given. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

K. SCHAIFEKS und H. H. VOIGT (Hrsg.) : Landolt-Bornstein. Zahlenwerte und Funktionen aus Naturwissenschaften und Technik,Neue Serie,Gruppe VI : Astronomie,Astrophysik und Weltraumforschung; Band 2, Astronomic und Astrophysik,Tcilband b: Sterne und Sternhaufcn,Springer-Vcrlag Berlin/Heidelberg/New York 1981. 456 Scitcn, 750,- DM     

E. A. Gußmann  G. Scholz 《Astronomische Nachrichten》1983,304(4):194-195

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High Effective Magnetic Field Strengths of the Magnetic Star 53 Camelopardalis     

G. Scholz 《Astronomische Nachrichten》1970,292(5):279-280

New measurements of the effective magnetic field strengths of 53 Cam yield essentially higher values than formerly published measurements. Three ZEEMAN -spectrograms yielded for the magnetic field +6800, – 11400 and – 7500 Gauß at the phases 0.17, 0.75 and 0.87 cycles after the positive crossover.  相似文献