Field investigation of dried lakes in western United States as an analogue to desiccation fractures on Mars

Potential Desiccation Polygons (PDPs), tens to hundreds of meters in size, have been observed in numerous regions on Mars, particularly in ancient (>3Gyr old) terrains of inferred paleolacustrine/playa geologic setting, and in association with hydrous minerals such as smectites. Therefore, a better understanding of the conditions in which large desiccation polygons form could yield unique insight into the ancient climate on Mars. Many dried lakebeds/playas in western United States display large (>50m wide) desiccation polygons, which we consider to be analogues for PDPs on Mars. Therefore, we have carried out fieldwork in seven of these dried lakes in San Bernardino and the Death Valley National Park regions complemented with laboratory and spectral analysis of collected samples. Our study shows that the investigated lacustrine/playa sediments have (a) a soil matrix containing 40-75% clays and fine silt (by volume) where the clay minerals are dominated by illite/muscovite followed by smectite, (b) carbonaceous mineralogy with variable amounts of chloride and sulfate salts, and significantly, (c) roughly similar spectral signatures in the visible-near-infrared (VIS-NIR) range. We conclude that the development of large desiccation fractures is consistent with water table retreat. In addition, the comparison of the mineralogical to the spectral observations further suggests that remote sensing VIS-NIR spectroscopy has its limitations for detailed characterization of lacustrine/playa deposits. Finally, our results imply that the widespread distribution of PDPs on Mars indicates global or regional climatic transitions from wet conditions to more arid ones making them important candidate sites for future in situ missions.

Einzelbemerkungen zur Lieferung 3 - 6 der Holtzmannschen Mischna-Ausgabe [Rezension] : (Fortsetzung von Jahrg. 1918, S. 70-75)

Viktor Aptowitzer

Figuren zwischen den Zeiten : Zu Scholem Alejchems 75. Geburtstag

Leo Hirsch

Na 50 Nachlass Arthur Schopenhauer - 'Schopenhauer-Archiv', 75 - Antwortschreiben mit Angaben über Blésimaires Tanzfähigkeiten

u.a.: Ortsbeschreibungen; Beschäftigung mit der Mathematik;

Na 1 Nachlass Max Horkheimer, 75 - Korrespondenzen u.a. mit Armin Hodler (p. II 9, 1-88b)

37 Briefe und Beilage zwischen Armin Hodler und Max Horkheimer, 1935-1948; 14 Briefe und Beilage zwischen Hans Honegger und Max Horkheimer, 1941-1946; 1 Brief und Beilage von Max Horkheimer an Paul Honigsheim, 1943; 9 Briefe zwischen Hans Horkheimer und Max Horkheimer, 1945-1948 sowie 1 Reisebericht, Peru, 1939; 2 Briefe zwischen Susanna Huber-Weisser und Max Horkheimer, 1949; 5 Briefe zwischen Helen MacGill-Hughes vom The American Journal of Sociology und Max Horkheimer, 1949; 1 Briefabschrift von Max Horkheimer an Edmund Husserl, 28.10.1931; 1 Brief von Elizabeth Husserl-Rosenberg, 06.01.1948;

Ms. Praed. 75 - Flores ex libris Bernhardi Claraevallensis

Vorbesitzer: Dominikanerkloster Frankfurt am Main

Na 50 Nachlass Arthur Schopenhauer - 'Schopenhauer-Archiv', 530 - Konzeptschreiben wegen angeblich falscher Berechnung des Bankguthabens

veröffentlicht in: Arthur Hübscher (Hrsg), Arthur Schopenhauer Gesammelte Briefe, Bonn 1978, Nr. 129

Ms.Ff.F.Stoltze 3. 75 - Brief von Wilhelm Jordan und Eugen Gantter von Frankfurter Journalisten- und Schriftsteller-Verein an Friedrich Stoltze

Glückwünsche zum 70. Geburtstag

Ms. lat. qu. 75 - Biblia sacra ex vulgata editione

Vorbesitzer: Johann Hartmann Beyer

Ms.Ff.F.Stoltze 3. 530 - Brief von Friedrich Stoltze an Unbekannt

Beerdigung Georg Herweghs, Verhinderung durch Krankheit und Arbeit

Erasmus Gruberus Pastor et Superintendens Ratisponensis An. Aet. 75. Minist. 46. Pastorat 17. 1684

Signatur des Originals: S 36/G03103

Ms. lat. oct. 75 - Dubia contra quatuor partes logicae

Vorbesitzer: Philipp Konrad Loskandt

INFANT MORTALITY IN THE MEXICAN AMERICAN COMMUNITY: AN ANALYSIS OF DIFFERENTIALS IN INFANT, NEONATAL, AND POSTNEONATAL MORTALITY BY ETHNICITY AND PARENTAL NATIVITY, 1974-75 SINGLE LIVE BIRTH COHORT, HARRIS COUNTY, TEXAS

The paradoxically low infant mortality rates for Mexican Americans in Texas have been attributed to inaccuracies in vital registration and idiosyncracies in Mexican migration in rural areas along the U.S.-Mexico border. This study examined infant (IMR), neonatal (NMR), and postneonatal (PNMR) mortality rates of Mexican Americans in an urban, non-border setting, using linked birth and death records of the 1974-75 single live birth cohort (N = 68,584) in Harris County, Texas, which includes the city of Houston and is reported to have nearly complete birth and death registration. The use of parental nativity with the traditional Spanish surname criterion made it possible to distinguish infants of Mexican-born immigrants from those of Blacks, Anglos, other Hispanics, and later-generation, more Anglicized Mexican Americans. Mortality rates were analyzed by ethnicity, parental nativity, and cause of death, with respect to birth weight, birth order, maternal age, legitimacy status, and time of first prenatal care.^ While overall IMRs showed Spanish surname rates slightly higher than Anglo rates, infants of Mexican-born immigrants had much lower NMRs than did Anglos, even for moderately low birth weight infants. However, among infants under 1500 grams, presumably unable to be discharged home in the neonatal period, Mexican Americans had the highest NMR. The inconsistency suggested unreported deaths for Mexican American low birth weight infants after hospital discharge. The PNMR of infants of Mexican immigrants was also lower than for Anglos, and the usual mortality differentials were reversed: high-risk categories of high birth order, high maternal age, and late/no prenatal care had the lowest PNMRs. Since these groups' characteristics are congruent with those of low-income migrants, the data suggested the possibility of migration losses. Cause of death analysis suggested that prematurity and birth injuries are greater problems than heretofore recognized among Mexican Americans, and that home births and "shoebox burials" may be unrecorded even in an urban setting.^ Caution is advised in the interpretation of infant mortality rates for a Spanish surname population of Mexican origin, even in an urban, non-border area with reportedly excellent birth and death registration. ^