Fine-tuning of age integrating magnetostratigraphy, radiocarbon dating, and carbonate cyclicity: Example of lacustrine sediments from Heqing basin (Yunnan, China) covering the past 1Myr

2007 ◽  
Vol 30 (3-4) ◽  
pp. 423-432 ◽  
Author(s):  
Shouyun Hu ◽  
Srinivasa Rao Goddu ◽  
Erwin Appel ◽  
Ken Verosub
2005 ◽  
Vol 136 (1) ◽  
pp. 123-129 ◽  
Author(s):  
Shouyun Hu ◽  
Srinivasa Rao Goddu ◽  
Erwin Appel ◽  
Ken Verosub ◽  
Yang Xiangdong ◽  
...  

Cells ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 113 ◽  
Author(s):  
Stephanie Maia Acuña ◽  
Lucile Maria Floeter-Winter ◽  
Sandra Marcia Muxel

An inflammatory response is essential for combating invading pathogens. Several effector components, as well as immune cell populations, are involved in mounting an immune response, thereby destroying pathogenic organisms such as bacteria, fungi, viruses, and parasites. In the past decade, microRNAs (miRNAs), a group of noncoding small RNAs, have emerged as functionally significant regulatory molecules with the significant capability of fine-tuning biological processes. The important role of miRNAs in inflammation and immune responses is highlighted by studies in which the regulation of miRNAs in the host was shown to be related to infectious diseases and associated with the eradication or susceptibility of the infection. Here, we review the biological aspects of microRNAs, focusing on their roles as regulators of gene expression during pathogen–host interactions and their implications in the immune response against Leishmania, Trypanosoma, Toxoplasma, and Plasmodium infectious diseases.


Radiocarbon ◽  
2020 ◽  
pp. 1-8
Author(s):  
Alyssa M Tate ◽  
Brittany Hundman ◽  
Jonathan Heile

ABSTRACT Leather has been produced by a variety of methods throughout human history, providing researchers unique insight into multiple facets of social and economic life in the past. Archaeologically recovered leather is often fragile and poorly preserved, leading to the use of various conservation and restoration efforts that may include the application of fats, oils, or waxes. Such additives introduce exogenous carbon to the leather, contaminating the specimen. These contaminants, in addition to those accumulated during interment, must be removed through chemical pretreatment prior to radiocarbon (14C) dating to ensure accurate dating. DirectAMS utilizes organic solvents, acid-base-acid (ABA) and gelatinization for all leather samples. Collagen yield from leather samples is variable due to the method of production and the quality of preservation. However, evaluating the acid-soluble collagen fraction, when available, provides the most accurate 14C dates for leather samples. In instances where gelatinization does not yield sufficient material, the resulting acid-insoluble fraction may be dated. Here we examine the effectiveness of the combined organic solvent and ABA pretreatment with gelatinization for leather samples, as well as the suitability of the acid-insoluble fraction for 14C dating.


Radiocarbon ◽  
2009 ◽  
Vol 51 (2) ◽  
pp. 601-611 ◽  
Author(s):  
A Zazzo ◽  
J-F Saliège ◽  
A Person ◽  
H Boucher

Over the past decade, radiocarbon dating of the carbonate contained in the mineral fraction of calcined bones has emerged as a viable alternative to dating skeletal remains in situations where collagen is no longer present. However, anomalously low δ13C values have been reported for calcined bones, suggesting that the mineral fraction of bone is altered. Therefore, exchange with other sources of carbon during heating cannot be excluded. Here, we report new results from analyses on cremated bones found in archaeological sites in Africa and the Near East, as well as the results of several experiments aiming at improving our understanding of the fate of mineral and organic carbon of bone during heating. Heating of modern bone was carried out at different temperatures, for different durations, and under natural and controlled conditions, and the evolution of several parameters (weight, color, %C, %N, δ13C value, carbonate content, crystallinity indexes measured by XRD and FTIR) was monitored. Results from archaeological sites confirm that calcined bones are unreliable for paleoenvironmental and paleodietary reconstruction using stable isotopes. Experimental results suggest that the carbon remaining in bone after cremation likely comes from the original inorganic pool, highly fractionated due to rapid recrystallization. Therefore, its reliability for 14C dating should be seen as close to that of tooth enamel, due to crystallographic properties of calcined bones.


Radiocarbon ◽  
1983 ◽  
Vol 25 (2) ◽  
pp. 639-644 ◽  
Author(s):  
H T Waterbolk

In the past 30 years many hundreds of archaeologic samples have been dated by radiocarbon laboratories. Yet, one cannot say that 14C dating is fully integrated into archaeology. For many archaeologists, a 14C date is an outside expertise, for which they are grateful, when it provides the answer to an otherwise insoluble chronologic problem and when it falls within the expected time range. But if a 14C date contradicts other chronologic evidence, they often find the ‘solution’ inexplicable. Some archaeologists are so impressed by the new method, that they neglect the other evidence; others simply reject problematic 14C dates as archaeologically unacceptable. Frequently, excavation reports are provided with an appendix listing the relevant 14C dates with little or no discussion of their implication. It is rare, indeed, to see in archaeologic reports a careful weighing of the various types of chronologic evidence. Yet, this is precisely what the archaeologist is accustomed to do with the evidence from his traditional methods for building up a chronology: typology and stratigraphy. Why should he not be able to include radiocarbon dates in the same way in his considerations?


2021 ◽  
Vol 10 (2) ◽  
pp. 60
Author(s):  
Sylvia Frisancho-Kiss

During the past decades, populous expansion in mast cell scientific literature came forth with more, than forty-four thousand PubMed publications available to date. Such surge is due to the appreciation of the momentous role of mast cells in the evolution of species, in the development and maintenance of vital physiological functions, such as reproduction, homeostasis, and fluids, diverse immunological roles, and the potential of far-reaching effects despite minute numbers. While the emerging knowledge of the importance of mast cells in equilibrium comes of age when looking at the matter from an evolutionary perspective, the recognition of mast cells beyond detrimental performance in allergies and asthma, during protection against parasites, falters. Beyond well known classical functions, mast cells can process and present antigens,can serve as a viral reservoir, can respond to hormones and xenobiotics,initiate antiviral and antibacterial responses, phagocytosis, apoptosis, and participate in important developmental cornerstones. During evolution,upon the development of a sophisticated niche of innate and adaptive cell populations, certain mast cell functions became partially transmutable,yet the potency of mast cells remained considerable. Reviewing mast cells enables us to reflect on the certitude, that our sophisticated, complex physiology is rooted deeply in evolution, which we carry ancient remnants of, ones that may have decisive roles in our functioning. This communication sets out the goal of characterizing mast cells, particularly the aspects less in limelight yet of immense significance, without the aspiration exhaust it all.


Radiocarbon ◽  
2013 ◽  
Vol 55 (3) ◽  
pp. 1085-1101 ◽  
Author(s):  
Bente Philippsen ◽  
Jan Heinemeier

The freshwater reservoir effect is a potential problem when radiocarbon dating fish bones, shells, human bones, or food crusts on pottery from sites near rivers or lakes. The reservoir age in hardwater rivers can be up to several thousand years and may be highly variable. Accurate 14C dating of freshwater-based samples requires knowing the order of magnitude of the reservoir effect and its degree of variability. Measurements on modern riverine materials may not give a single reservoir age correction that can be applied to archaeological samples, but they show the order of magnitude and variability that can also be expected for the past. This knowledge will be applied to the dating of food crusts on pottery from the Mesolithic sites Kayhude at the Alster River and Schlamersdorf at the Trave River, both in Schleswig-Holstein, northern Germany.


2020 ◽  
Vol 21 (21) ◽  
pp. 8085
Author(s):  
Giacomo Forti ◽  
Andrea Nitti ◽  
Peshawa Osw ◽  
Gabriele Bianchi ◽  
Riccardo Po ◽  
...  

The introduction of the IDIC/ITIC families of non-fullerene acceptors has boosted the photovoltaic performances of bulk-heterojunction organic solar cells. The fine tuning of the photophysical, morphological and processability properties with the aim of reaching higher and higher photocurrent efficiencies has prompted uninterrupted worldwide research on these peculiar families of organic compounds. The main strategies for the modification of IDIC/ITIC compounds, described in several contributions published in the past few years, can be summarized and classified into core modification strategies and end-capping group modification strategies. In this review, we analyze the more recent advances in this field (last two years), and we focus our attention on the molecular design proposed to increase photovoltaic performance with the aim of rationalizing the general properties of these families of non-fullerene acceptors.


Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 983 ◽  
Author(s):  
Adrian Patrut ◽  
Stephan Woodborne ◽  
Roxana T. Patrut ◽  
Grant Hall ◽  
Laszlo Rakosy ◽  
...  

The year 2016 witnessed the fall of a symbol of the botanical world: the historic Chapman baobab of Botswana. This article presents the results of our investigation of the standing and fallen tree. The Chapman baobab had an open ring-shaped structure composed of six partially fused stems. Several wood samples collected from the stems prior and after their collapse were analysed by using radiocarbon dating. The radiocarbon date of the oldest sample was 1381 ± 22 BP, which corresponds to a calibrated age of 1345 (+10, −15) calendar years. The dating results show that the six stems of the Chapman baobab belonged to three different generations, which were 1350–1400, 800–1000 and 500–600 years old. The growth rate variation of the largest and oldest stem is presented and correlated with the climate evolution in the area over the past 1000 years. The factors that determined the sudden fall and death of the Chapman baobab are also presented and discussed.


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