Biomarkers: Molecular Fossils

1988 ◽  
Vol 1 ◽  
pp. 98-113 ◽  
Author(s):  
Roger E. Summons
Keyword(s):  
Organic Matter ◽  
Organic Compounds ◽  
Recent Progress ◽  
Organic Geochemistry ◽  
New Developments ◽  
Molecular Fossils ◽  
Primary Literature ◽  
History Of ◽  
Biomarker Research ◽  
Made In

Curiosity about the history of life on our planet is a major motivational force for earth scientists. Fossil organic compounds, the components of petroleum and sedimentary organic matter, record aspects of the evolution of the biosphere from as far back as 1.8 billion years and perhaps longer. Elucidation of this record is continually advancing as a result of the concerted interests and efforts of geologists, biologists and chemists. It is also aided by advances in technique and instrumentation. Fascinating new developments and insights abound. In this paper I review some early landmarks and discuss the recent progress made in organic geochemistry, particularly as it applies to biomarker research. The examples of recent work are heavily biased toward my own interests and are not intended to be comprehensive. Because the literature citations are also selective and rely heavily on reviews, readers are advised to seek out the primary literature for accurate detail of specific subjects.

scholarly journals XXIII.—Some Account of the Recent Progress of Sanskrit Studies

1863 ◽  
Vol 23 (2) ◽  
pp. 253-283
Author(s):  
J. Muir
Keyword(s):  
Present State ◽  
Recent Progress ◽  
Indian Literature ◽  
History Of ◽  
The Subject ◽  
Made In

In compliance with the desire which the Council have done me the honour to express, I have drawn up the following account of the recent progress and present state of Sanskrit studies, prefixing such an outline of the earlier history of these researches as may serve to complete the review, and render it more easily intelligible.In this sketch I do not profess to communicate anything new, but merely seek to present such a summary of the results already obtained, as may convey to those who have not bestowed any special attention on the subject some idea of the character and affinities of the Sanskrit language, and of the nature and contents of Indian literature, as well as of the advances which have of late years been made in the principal branches of the study.

Thrombolytic Therapy for Acute Ischemic Stroke: Past and Future

2019 ◽  
Vol 25 (3) ◽  
pp. 242-250 ◽  
Author(s):  
Keita Shibata ◽  
Terumasa Hashimoto ◽  
Takuro Miyazaki ◽  
Akira Miyazaki ◽  
Koji Nobe
Keyword(s):  
Clinical Trials ◽  
Ischemic Stroke ◽  
Thrombolytic Therapy ◽  
Clinical Studies ◽  
Recent Progress ◽  
Time Window ◽  
The Us ◽  
History Of ◽  
Ongoing Development ◽  
Made In

Background: Thromboembolic ischemic stroke, which is mainly caused by hypertension, as well as plasma dyslipidemia, arterial fibrillation and diabetes, is a leading cause of death in the US and other countries. Numerous clinical trials for thrombolytic drugs, which aimed to pharmacologically dissolve thrombi, were conducted in the 1950s, when the first thrombolytic therapy was performed. Methods: In this study, we summarize the pathophysiologic features of ischemic stroke, and the history of thrombolytic therapy, and discuss the recent progress that has been made in the ongoing development of thrombolytic drugs. Conclusion: Thrombolytic therapy is sometimes accompanied by harmful hemorrhagic insults; accordingly, a window of time wherein therapy can safely be performed has been established for this approach. Several basic and clinical studies are ongoing to develop next-generation thrombolytic drugs to expand the time window

Late Glacial and Holocene 14 C-Dated Fossil Soils in the Middle Vistula Valley

2012 ◽  
Vol 63 (4) ◽  
pp. 50-60 ◽  
Author(s):  
Krystyna Konecka-Betley
Keyword(s):  
Organic Matter ◽  
Radiocarbon Dating ◽  
Late Glacial ◽  
Organic Soils ◽  
Vistula River ◽  
Organic Horizons ◽  
History Of ◽  
Late Glacial And Holocene ◽  
Peat Horizon ◽  
Made In

Abstract Transformations of the natural environment in the area surrounding and encompassing the Vistula River valley during the last 20 000 years BP should be discussed with regard to radiocarbon dating of the organic matter in the documented fossil soils. Part of the 14C dates from horizons A of pedosols in the valley have already been published, for the upper part of the valley by Balwierz & Nalepka [1992], and for the lower part - by Turkowska [1992]. Palynologic analysis was also made in many of the documented sites. The most important events in the history of the valley have been supplemented by radiocarbon dating by Starkel [2001]. This report presents 14C dates measured in the buried organic horizons of fossil soils in the Middle Vistula valley between Stężyca (Dęblin area) to Liszyno (Płock area). Most datings were made in the Kampinos Forest. For mineral-organic soils the dates lie between 1080 ± 90 Gd. 19S, Laski [Urbaniak-Biernacka 1973] and 12 160 ± 260 [Gd. 4391, Mariew [Konecka-Betley 1991]. In turn, the base of the oldest peat horizon in the Kampinos Forest supplied a date of 10 S90 ± 340 Gd. 2260, Wilków [Konecka-Betley et al. 1991].

scholarly journals Molecular fossils within bitumens and kerogens from the ~ 1 Ga Lakhanda Lagerstätte (Siberia, Russia) and their significance for understanding early eukaryote evolution

PalZ ◽  
2021 ◽  
Author(s):  
Jan-Peter Duda ◽  
Hannah König ◽  
Manuel Reinhardt ◽  
Julia Shuvalova ◽  
Pavel Parkhaev
Keyword(s):  
Organic Matter ◽  
Organic Geochemistry ◽  
Anaerobic Bacteria ◽  
Peak Oil ◽  
Molecular Fossil ◽  
Molecular Fossils ◽  
Eukaryote Evolution ◽  
Organic Biomarkers ◽  
Major Emphasis ◽  
Maturity Parameters

AbstractThe emergence and diversification of eukaryotes during the Proterozoic is one of the most fundamental evolutionary developments in Earth’s history. The ca. 1-billion-year-old Lakhanda Lagerstätte (Siberia, Russia) contains a wealth of eukaryotic body fossils and offers an important glimpse into their ecosystem. Seeking to complement the paleontological record of this remarkable lagerstätte, we here explored information encoded within sedimentary organic matter (total organic carbon = 0.01–1.27 wt.%). Major emphasis was placed on sedimentary hydrocarbons preserved within bitumens and kerogens, including molecular fossils (or organic biomarkers) that are specific to bacteria and eukaryotes (i.e. hopanes and regular steranes, respectively). Programmed pyrolysis and molecular organic geochemistry suggest that the organic matter in the analyzed samples is about peak oil window maturity and thus sufficiently well preserved for detailed molecular fossil studies that include hopanes and steranes. Together with petrographic evidence as well as compositional similarities of the bitumens and corresponding kerogens, the consistency of different independent maturity parameters establishes that sedimentary hydrocarbons are indigenous and syngenetic to the host rock. The possible presence of trace amounts of hopanes and absence of steranes in samples that are sufficiently well preserved to retain both types of compounds evidences an environment dominated by anaerobic bacteria with no or very little inputs by eukaryotes. In concert with the paleontological record of the Lakhanda Lagerstätte, our study adds to the view that eukaryotes were present but not significant in Mesoproterozoic ecosystems.

The Tempo and mode(S) of Prebiotic Evolution

1997 ◽  
Vol 161 ◽  
pp. 419-429 ◽  
Author(s):  
Antonio Lazcano
Keyword(s):  
Origin Of Life ◽  
Organic Compounds ◽  
Biological Evolution ◽  
Current Evidence ◽  
Early Diversification ◽  
Time Period ◽  
The Galaxy ◽  
History Of ◽  
Widespread Phenomenon ◽  
The Origin Of Life

AbstractDifferent current ideas on the origin of life are critically examined. Comparison of the now fashionable FeS/H2S pyrite-based autotrophic theory of the origin of life with the heterotrophic viewpoint suggest that the later is still the most fertile explanation for the emergence of life. However, the theory of chemical evolution and heterotrophic origins of life requires major updating, which should include the abandonment of the idea that the appearance of life was a slow process involving billions of years. Stability of organic compounds and the genetics of bacteria suggest that the origin and early diversification of life took place in a time period of the order of 10 million years. Current evidence suggest that the abiotic synthesis of organic compounds may be a widespread phenomenon in the Galaxy and may have a deterministic nature. However, the history of the biosphere does not exhibits any obvious trend towards greater complexity or «higher» forms of life. Therefore, the role of contingency in biological evolution should not be understimated in the discussions of the possibilities of life in the Universe.

A history of botanical collections in the Luangwa Valley, Zambia

1998 ◽  
Vol 25 (2) ◽  
pp. 283-291
Author(s):  
P.S.M. PHIRI ◽  
D.M. MOORE
Keyword(s):  
Eighteenth Century ◽  
Environmental Impact ◽  
Impact Assessment ◽  
Vascular Plants ◽  
Central Africa ◽  
Peak Activity ◽  
Historical Account ◽  
History Of ◽  
The 1960S ◽  
Made In

Central Africa remained botanically unknown to the outside world up to the end of the eighteenth century. This paper provides a historical account of plant explorations in the Luangwa Valley. The first plant specimens were collected in 1897 and the last serious botanical explorations were made in 1993. During this period there have been 58 plant collectors in the Luangwa Valley with peak activity recorded in the 1960s. In 1989 1,348 species of vascular plants were described in the Luangwa Valley. More botanical collecting is needed with a view to finding new plant taxa, and also to provide a satisfactory basis for applied disciplines such as ecology, phytogeography, conservation and environmental impact assessment.

Elements for a General Organology

Derrida Today ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 72-94
Author(s):  
Bernard Stiegler
Keyword(s):  
Organic Matter ◽  
Planetary Scale ◽  
General Account ◽  
Inorganic Matter ◽  
History Of

These lectures outline the project of a general organology, which is to say an account of life when it is no longer just biological but technical, or when it involves not just organic matter but organized inorganic matter. This organology is also shown to require a modified Simondonian account of the shift from vital individuation to a three-stranded process of psychic, collective and technical individuation. Furthermore, such an approach involves extending the Derridean reading of Socrates's discussion of writing as a pharmakon, so that it becomes a more general account of the pharmacological character of retention and protention. By going back to Leroi-Gourhan, we can recognize that this also means pursuing the history of retentional modifications unfolding in the course of the history of what, with Lotka, can also be called exosomatization. It is thus a question of how exteriorization can, today, in an epoch when it becomes digital, and in an epoch that produces vast amounts of entropy at the thermodynamic, biological and noetic levels, still possibly produce new forms of interiorization, that is, new forms of thought, care and desire, amounting to so many chances to struggle against the planetary-scale pharmacological crisis with which we are currently afflicted.

Chasing Angels: The Sweet Wine Angelica

2008 ◽  
Vol 8 (3) ◽  
pp. 74-78
Author(s):  
hank shaw
Keyword(s):  
The State ◽  
The Real ◽  
Mission Period ◽  
History Of ◽  
Uncertain Future ◽  
Sweet Wine ◽  
Made In

Portugal has port, Spain has sherry, Sicily has Marsala –– and California has angelica. Angelica is California's original wine: The intensely sweet, fortified dessert cordial has been made in the state for more than two centuries –– primarily made from Mission grapes, first brought to California by the Spanish friars. Angelica was once drunk in vast quantities, but now fewer than a dozen vintners make angelica today. These holdouts from an earlier age are each following a personal quest for the real. For unlike port and sherry, which have strict rules about their production, angelica never gelled into something so distinct that connoisseurs can say, ““This is angelica. This is not.”” This piece looks at the history of the drink, its foggy origins in the Mission period and on through angelica's heyday and down to its degeneration into a staple of the back-alley wino set. Several current vintners are profiled, and they suggest an uncertain future for this cordial.

Not as It Is Written

2020 ◽  
Vol 42 (2) ◽  
pp. 78-100
Author(s):  
Benjamin Houston
Keyword(s):  
African American ◽  
Civil Rights ◽  
Oral History ◽  
Civil Rights Movement ◽  
International Exhibition ◽  
Black Experience ◽  
American Perspective ◽  
History Of ◽  
Black Life ◽  
Made In

This article discusses an international exhibition that detailed the recent history of African Americans in Pittsburgh. Methodologically, the exhibition paired oral history excerpts with selected historic photographs to evoke a sense of Black life during the twentieth century. Thematically, showcasing the Black experience in Pittsburgh provided a chance to provoke among a wider public more nuanced understandings of the civil rights movement, an era particularly prone to problematic and superficial misreadings, but also to interject an African American perspective into the scholarship on deindustrializing cities, a literature which treats racism mostly in white-centric terms. This essay focuses on the choices made in reconciling these thematic and methodological dimensions when designing this exhibition.

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