Laudatio für Prof. Schreyer zur Verleihung der Steinmann-Medaille,Bochum, September 2003     

Friedrich?SeifertEmail author 《International Journal of Earth Sciences》2004,93(2):169-171

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APEX and ATCA observations of the southern hot core G327.3-0.6 and its environs     

Friedrich Wyrowski  Per Bergman  Karl Menten  Jürgen Ott  Peter Schilke  Sven Thorwirth 《Astrophysics and Space Science》2008,313(1-3):69-72

There is no generally accepted evolutionary scheme for high mass star formation yet. A simple approach to address this problem is to cover several of the known stages during the formation of massive stars in the same cloud and then investigate their properties trying to construct an evolutionary sequence. Here we present such a project conducted with complementary APEX and ATCA observations. These observations show a compact and bright single hot core in the G327.3-0.6 region on a 0.03 pc scale with a mass of 500 M_⊙ and 0.5–1.5 10⁵ L_⊙. Additionally a clumpy filament is seen in N₂H⁺. Together with cm continuum observations, the data reveal like pearls on a string several stages of massive star formation, with likely the youngest stages hiding in the cold N₂H⁺ cores analysed with a multilevel study of the APEX and ATCA observations.  相似文献   

Experimental impacts into chondritic targets,part I: Disruption of an L6 chondrite by multiple impacts     

Mark J. CINTALA  Friedrich HöRZ 《Meteoritics & planetary science》2008,43(4):771-803

Abstract— A fragment of an L6 chondrite (Allan Hills [ALH] 85017,13) with an initial mass (M₀) of 464.1 g was the target in a series of experimental impacts in which the largest remaining fragment (M_R) after each shot was impacted by a 3.18 mm ceramic sphere at a nominal speed of 2 km s^?1. This continued until the mass of the largest remaining piece was less than half the mass of the target presented to that shot (M_S). Two chunks of Bushveldt gabbro with similar initial masses were also impacted under the same conditions until M_R was less than half M₀. The two gabbro targets required a total of 1.51 × 10⁷ and 1.75 × 10⁷ erg g^?1 to attain 0.27 and 0.33 M_R/M₀, respectively; the chondrite, however, was considerably tougher, reaching 0.40 and 0.21 M_R/M₀ only after receiving 2.37 × 10⁷ and 3.10 × 10⁷ erg g^?1, respectively. The combined ejecta and spallation products from the gabbro impacts were coarser than those from the chondrite and in sufficient quantities that the new surface areas exceeded those from the meteorite until the fifth shot in the chondrite series, which was the number of impacts required to disrupt each gabbro target (i.e., M_R/M₀ ≤ 0.5). Unlike the behavior shown in previous regolith‐evolution series, neither gabbro target produced an enhancement in the size fraction reflecting the mean size of the crystals composing the rock (about 3 mm), an effect possibly related to the width of the shock pulse. The original chondrite was so fine‐grained and fractured, and the variance in its grain‐size distribution so large, that effects related to grain size were relegated to the<63 μm fraction. Impacts into ALH 85017 produced abundant, fine‐grained debris, but otherwise the slopes of its size distributions were comparable to those from other experiments involving natural and fabricated terrestrial targets. The characteristic slopes of the chondrite's size distributions, however, were notably more constant over the entire nine‐impact series than those from any of the terrestrial targets, a testament to the control over comminution apparently exerted by pre‐existing fractures and other, microscopic damage in the meteorite. The enhancement in the finer fraction of debris from ALH 85017 indicates that ordinary chondrites in solar orbit would be very efficient contributors to the cosmic‐dust complex. At the same time, the greater resistance to disruption displayed by ordinary chondrites relative to that exhibited by igneous rocks indicates that a selection effect could be operative between the annealed, ordinary‐chondritic breccias and relatively weaker, differentiated meteorites. Preferential survival from their time in the regoliths of their parent bodies through their transit to Earth and passage through the atmosphere suggests that meteorite collections could be biased in favor of the ordinary chondrites.  相似文献   

Effect of polychromatic X‐ray microtomography imaging on the amino acid content of the Murchison CM chondrite     

Jon M. Friedrich  Hannah L. McLain  Jason P. Dworkin  Daniel P. Glavin  W. Henry Towbin  Morgan Hill  Denton S. Ebel 《Meteoritics & planetary science》2019,54(1):220-228

X‐ray microcomputed tomography (μCT) is a useful means of characterizing cosmochemical samples such as meteorites or robotically returned samples. However, there are occasional concerns that the use of μCT may be detrimental to the organic components of a chondrite. Small organic compounds such as amino acids comprise up to ~10% of the total solvent extractable carbon in CM carbonaceous chondrites. We irradiated three samples of the Murchison CM carbonaceous chondrite under conditions akin to and harsher than those typically used during typical benchtop X‐ray μCT imaging experiments to determine if detectable changes in the amino acid abundance and distribution relative to a nonexposed Murchison control sample occurred. After subjecting three meteorite samples to ionizing radiation dosages between ~300 Gray (Gy) and 3 kGy with bremstrahlung X‐rays, we analyzed the amino acid content of each sample. Within sampling and analytical errors, we cannot discern differences in the amino acid abundances and amino acid enantiomeric ratios when comparing the control samples (nonexposed Murchison) and the irradiated samples. We conclude that a polychromatic X‐ray μCT experiment does not alter the abundances of amino acids to a degree greater than how well those abundances are measured with our techniques and therefore any damage to amino acids is minimal.  相似文献   

Neuerscheinungen     

Bubnoff  Kienow  Friedrich Becker  Correns  Wilckens 《International Journal of Earth Sciences》1941,32(1-2):199-205

Ohne Zusammenfassung  相似文献   

Untersuchungen über die Mächtigkeit von Schlickschichten mit Hilfe des Echographen     

Friedrich Schüler 《Ocean Dynamics》1952,5(5-6):220-231

Zusammenfassung Es wird über eine Methode zur Feststellung von Schlickmächtigkeiten, von Bodenschichtungen in weichem Boden und zur Ermittlung des Tiefenprofils des harten Untergrundes berichtet. An Hand von Echogrammen und im Vergleich mit Bodenproben wird die Methode diskutiert.

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Investigations into the thickness of mud layers with the aid of ultra sound records

Summary A method is discussed allowing to make investigations into the thickness of mud layers and to ascertain the stratification in soft ground as well as to reveal the relief of the solid substratum of the sea bottom. The method is explained by the aid of ultra sound records which are compared with bottom samples.

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Recherches sur l'épaisseur des couches vaseuses au moyen d'enregistrements d'ondes ultrasonores

Résumé Une méthode est exposée qui permet de déterminer qualitativement l'épaisseur de couches vaseuses, d'explorer la stratification dans des fonds meubles et de découvrir le relief du substratum solide du fond de la mer. Ensuite, cette méthode est illustrée à l'aide d'enregistrements d'ondes ultrasonores qui sont comparés avec des échantillons du fond de la mer.

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Handlotungen und Echolotungen in der Seevermessung geringer Wassertiefen in strömenden Gewässern — eine kritische Betrachtung     

Friedrich Schüler 《Ocean Dynamics》1952,5(1):6-21

Zusammenfassung Vergleichslotungen zwischen Echolot und Handlot führen zu einer mathematischen Ableitung der Handlotleinen-Kurve in strömenden Gewässern. Durch Einführung von zwei Vereinfachungen — Vernachlässigung des Lotleinen-Gewichts und Annahme der Konstanz der Strömungsgeschwindigkeit nach der Tiefe — wird theoretisch die Kettenlinie, praktisch eine Parabel ermittelt. Als bestimmend für den Parameter der Kettenlinie ergeben sich das Lotgewicht und der Staudruck auf die Lotleine. Aus einem praktischen Beispiel wird der Parameter entnommen, und es werden für diese Verhältnisse die für die Tiefenwerte bis 26 m zu erwartenden Fehlmessungen des Handlotes sowie die Größe der Ablagen der Lotbirne vom Lotpunkt berechnet. Für andere Werte der Strömungsgeschwindigkeit werden die Veränderungen auf die Ausbuchtung der Lotleine ebenfalls rechnerisch bestimmt und in Kurven dargestellt. Aus diesen Kurven ergeben sich zwangsläufig die größten Tiefen, die man bei verschiedenen Strömungsgeschwindigkeiten mit dem schweren Handlot vermessen darf; sie liegen bei v=1 m/sec bei 8 m, bei v=0,7 m/sec bei 12 m und bei v=0,5 m/sec bei 20 m Wassertiefe.Praktische Beispiele der Seevermessung aus der jüngsten Zeit zeigen deutlich die Notwendigkeit, zukünftig nur noch mit dem Echolot zu vermessen.

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A comment on the applicability of hand leads and echo sounders to surveying operations in flowing shallow waters

Summary From comparisons between hand-lead soundings and echo soundings in streaming waters the divergency of the lead line from the vertical is mathematically derived. In introducing two simplifications, i. e. in neglecting the weight of the lead line and in assuming the velocity of current to be constant at all depths, the catenary curve which practically speaking is a parabola, is theoretically ascertained. The weight of the lead and the dynamic pressuro of the water (the pressure as exerted on a jet and measured by it) are found to be decisive for the parameter of the catenary-curve. The parameter is derived from a practical example and, according to the conditions of same, the errors to be expected in sounding with the hand lead at depths up to 26 m (= 79 ft) as well as the divergency of the sounding lead from the vertical are calculated. The various degrees of the lead line's divergency caused by a greater or lesser intensity of the current are likewise calculated and represented by curves. These curves necessarily indicate the maximum depths that can be sounded with sufficient accuracy with the heavy hand lead (5 kilos) at different velocities of current; the approximate values are as follows: 8 m for 1,0 m/sec, 12 m for 0,7 m/sec, 20 m for 0,5 m/sec (or: 25 ft for 2,0 knots, 37 ft for 1,5 knots, 61 ft for 1,0 knot). As a result of practical experience in recent survey operations the echo sounder should be regarded as the only reliable instrument to be used in future surveying.

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Note critique sur l'applicabilité de la sonde au plomb-poisson et celle du sondeur acoustique aux levés hydrographiques effectués en faibles profondeurs dans les eaux courantes

Résumé Les comparaisons des sondages au plomb-poisson avec ceux effectués par écho permettent d'en dériver mathématiquement la courbe formée par la ligne de sonde dans des eaux courantes. En introduisant deux simplifications, c'est à dire en négligeant le poids de la ligne et en supposant que la vitesse de courant soit constante dans toutes les profondeurs on arrive à déterminer théoriquement la chaînette qui est en effet une parabole. Le paramètre est fonction du poids du plomb-poisson et celle de la poussée sensiblement horizontale sur le fil due au frottement du liquide. On se sert d'un exemple pratique pour en dériver le paramètre, pour calculer, dans les conditions de cet exemple, les sondages faux de la sonde au plomb-poisson dont il faut tenir compte dans les profondeurs jusqu'à 26 m, et pour déterminer la déviation entre le plomb au bout de la ligne et la verticale. Les diverses variations de la courbe, que la ligne subit et qui sont causées par d'autres valeurs de la vitesse de courant sont aussi calculées et représentées à l'aide des courbes. Ces courbes indiquent forcément les profondeurs permettant encore une précision suffisante du sondage au plombpoisson lourd (5 kg) aux différentes variations de la vitesse de courant. Ces maxima sont à peu près comme suit:v=1,0 m/sec à 8 m de profondeur,v=0,7 m/sec à 12 m de profondeur,v=0,5 m/sec à 20 m de profondeur. Des exemples pratiques offerts par des récentes levés hydrographiques prouvent que le sondeur acoustique doit être considéré comme le seul instrument assurant le précis levé hydrographique.

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Kurzer Bericht über die sedimentpetrographische Untersuchung zweier Lotkerne der Albatross-Expedition     

Dr. Friedrich Wilhelm Locher 《Contributions to Mineralogy and Petrology》1952,3(3):193-218

Ohne Zusammenfassung  相似文献   

Die Bedeutung der Atmosphärischen Wasserzirkulation für das Klima der Vorzeit     

Friedrich Schuh 《International Journal of Earth Sciences》1952,40(1):179-180

Ohne ZusammenfassungAuf der Heimfahrt von der Jahresversammlung der Geologischen Vereinigung in Köln, auf der das Thema Klima der Vorzeit behandelt wurde, drängte sich mir bei meinen rückschauenden Betrachtungen ein Klimafaktor auf, der bei der Tagung nicht erwähnt worden war und auch sonst wohl kaum in die Diskussion gezogen wurde, der mir aber doch beachtenswert scheint. So sollen die folgenden Zeilen gewissermaßen als nachträgliche Diskussionsbemerkung gewertet werden.  相似文献   

Stellenangebote und Stellengesuche     

Dr. Friedrich Schwarz 《International Journal of Earth Sciences》1931,22(5):352-352

Ohne Zusammenfassung  相似文献