Publications by authors named "W J Rink"

26 Publications

  • Page 1 of 1

Decoration of Coiled-Coil Peptides with N-Cysteine Peptide Thioesters As Cyclic Peptide Precursors Using Copper-Catalyzed Azide-Alkyne Cycloaddition (CuAAC) Click Reaction.

Org Lett 2018 12 8;20(23):7493-7497. Epub 2018 Nov 8.

Institute of Organic and Biomolecular Chemistry, Georg-August Universität Göttingen , Tammannstraße 2 , 37077 Göttingen , Germany.

The development of a copper-catalyzed azide-alkyne cycloaddition (CuAAC) protocol for the decoration of coiled coils with N-cysteine peptide thioesters as cyclic peptide precursors is presented. The reaction conditions include tert-butanol/PBS as the solvent and CuSO/THPTA/ascorbate as the catalytic system. During these studies, partial formylation of N-terminal cysteine peptides is observed. Mechanistic analysis leads to identification of the formyl source and, hence, to the development of reaction conditions, under which the undesired side reaction was suppressed.
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http://dx.doi.org/10.1021/acs.orglett.8b03261DOI Listing
December 2018

De Novo Designed α-Helical Coiled-Coil Peptides as Scaffolds for Chemical Reactions.

Chemistry 2019 Feb 28;25(7):1665-1677. Epub 2018 Nov 28.

Institute of Organic and Biomolecular Chemistry, Georg-August-Universität Göttingen, Tammannstraße 2, 37077, Göttingen, Germany.

Coiled coils (CCs) are well-understood protein-folding motifs. They appear in a variety of oligomer states and as homo- and heteromeric assemblies. This versatility and the general accessibility by de novo design makes them ideal building blocks for synthetic biology. This Minireview highlights the efforts being made in designing small peptide catalysts or reaction templates based on the CC scaffold. The first reports described autocatalysis or mediation of peptide ligation based on CC recognition. Over the years, the designs became more advanced, catalyzing ester hydrolysis, acyl transfer and redox reactions with partial enzyme-like reactivity. Due to the ability to control CC assembly, and, in heterodimeric systems, the association and dissociation, the CC motif has become a common peptide tag in chemical biology.
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http://dx.doi.org/10.1002/chem.201802849DOI Listing
February 2019

Evidence of an early projectile point technology in North America at the Gault Site, Texas, USA.

Sci Adv 2018 07 11;4(7):eaar5954. Epub 2018 Jul 11.

Texas Archaeological Research Laboratory, The University of Texas at Austin, 1 University Station, R7500, Austin, TX 78712, USA.

American archeology has long been polarized over the issue of a human presence in the Western Hemisphere earlier than Clovis. As evidence of early sites across North and South America continues to emerge, stone tool assemblages appear more geographically and temporally diverse than traditionally assumed. Within this new framework, the prevailing models of Clovis origins and the peopling of the Americas are being reevaluated. This paper presents age estimates from a series of alluvial sedimentary samples from the earliest cultural assemblage at the Gault Site, Central Texas. The optically stimulated luminescence age estimates (~16 to 20 thousand years ago) indicate an early human occupation in North America before at least ~16 thousand years ago. Significantly, this assemblage exhibits a previously unknown, early projectile point technology unrelated to Clovis. Within a wider context, this evidence suggests that Clovis technology spread across an already regionalized, indigenous population.
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http://dx.doi.org/10.1126/sciadv.aar5954DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6040843PMC
July 2018

Kinetic studies on strand displacement in designed parallel heterodimeric coiled coils.

Chem Sci 2018 May 17;9(18):4308-4316. Epub 2018 Apr 17.

Georg-August-Universität Göttingen , Institute of Organic and Biomolecular Chemistry , Tammannstraße 2 , 37077 Göttingen , Germany . Email:

Among the protein folding motifs, which are accessible by design, the parallel heterodimeric coiled coil is most frequently used in bioinspired applications and chemical biology in general. This is due to the straightforward sequence-to-structure relationships, which it has in common with all coiled-coil motifs, and the heterospecificity, which allows control of association. Whereas much focus was laid on designing orthogonal coiled coils, systematic studies on controlling association, for instance by strand displacement, are rare. As a contribution to the design of dynamic coiled-coil-based systems, we studied the strand-displacement mechanism in obligate heterodimeric coiled coils to investigate the suitability of the dissociation constants () as parameters for the prediction of the outcome of strand-displacement reactions. We use two sets of heterodimeric coiled coils, the previously reported N-A B and the newly characterized C-A B . Both comprise values in the μM to sub-nM regime. Strand displacement is explored by CD titration and a FRET-based kinetic assay and is proved to be an equilibrium reaction with half-lifes from a few seconds up to minutes. We could fit the displacement data by a competitive binding model, giving rate constants and overall affinities of the underlying association and dissociation reactions. The overall affinities correlate well with the ratios of values determined by CD-thermal denaturation experiments and, hence, support the dissociative mechanism of strand displacement in heterodimeric coiled coils. From the results of more than 100 different displacement reactions we are able to classify three categories of overall affinities, which allow for easy prediction of the equilibrium of strand displacement in two competing heterodimeric coiled coils.
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http://dx.doi.org/10.1039/c7sc05342hDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5944379PMC
May 2018

Sequential Subterranean Transport of Excavated Sand and Foraged Seeds in Nests of the Harvester Ant, Pogonomyrmex badius.

PLoS One 2015 28;10(10):e0139922. Epub 2015 Oct 28.

Department of Biological Science, Florida State University, Tallahassee, Florida, United States of America.

During their approximately annual nest relocations, Florida harvester ants (Pogonomyrmex badius) excavate large and architecturally-distinct subterranean nests. Aspects of this process were studied by planting a harvester ant colony in the field in a soil column composed of layers of 12 different colors of sand. Quantifying the colors of excavated sand dumped on the surface by the ants revealed the progress of nest deepening to 2 m and enlargement to 8 L in volume. Most of the excavation was completed within about 2 weeks, but the nest was doubled in volume after a winter lull. After 7 months, we excavated the nest and mapped its structure, revealing colored sand deposited in non-host colored layers, especially in the upper 30 to 40 cm of the nest. In all, about 2.5% of the excavated sediment was deposited below ground, a fact of importance to sediment dating by optically-stimulated luminescence (OSL). Upward transport of excavated sand is carried out in stages, probably by different groups of ants, through deposition, re-transport, incorporation into the nest walls and floors and remobilization from these. This results in considerable mixing of sand from different depths, as indicated in the multiple sand colors even within single sand pellets brought to the surface. Just as sand is transported upward by stages, incoming seeds are transported downward to seed chambers. Foragers collect seeds and deposit them only in the topmost nest chambers from which a separate group of workers rapidly transports them downward in increments detectable as a "wave" of seeds that eventually ends in the seed chambers, 20 to 80 cm below the surface. The upward and downward transport is an example of task-partitioning in a series-parallel organization of work carried out by a highly redundant work force in which each worker usually completes only part of a multi-step process.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0139922PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4624972PMC
June 2016

New radiometric ages for the BH-1 hominin from Balanica (Serbia): implications for understanding the role of the Balkans in Middle Pleistocene human evolution.

PLoS One 2013 6;8(2):e54608. Epub 2013 Feb 6.

School of Geography and Earth Sciences, McMaster University, Hamilton, Ontario, Canada.

Newly obtained ages, based on electron spin resonance combined with uranium series isotopic analysis, and infrared/post-infrared luminescence dating, provide a minimum age that lies between 397 and 525 ka for the hominin mandible BH-1 from Mala Balanica cave, Serbia. This confirms it as the easternmost hominin specimen in Europe dated to the Middle Pleistocene. Inferences drawn from the morphology of the mandible BH-1 place it outside currently observed variation of European Homo heidelbergensis. The lack of derived Neandertal traits in BH-1 and its contemporary specimens in Southeast Europe, such as Kocabaş, Vasogliano and Ceprano, coupled with Middle Pleistocene synapomorphies, suggests different evolutionary forces acting in the east of the continent where isolation did not play such an important role during glaciations.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0054608PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3566111PMC
December 2013

Single-aliquot EPR dosimetry of wallboard (drywall).

Radiat Prot Dosimetry 2011 Nov 11;147(4):512-6. Epub 2011 Jan 11.

Atomic Energy of Canada Limited, Chalk River Laboratories, Chalk River, ON, Canada.

Electron paramagnetic resonance spectra and dose-response curves are presented for a variety of wallboard samples obtained from different manufacturing facilities, as well as for source gypsum and anhydrite. The intensity of the CO(3)(-) paramagnetic centre (G2) is enhanced with gamma radiation. Isothermal decay curves are used to propose annealing methods for the removal of the radiosensitive CO(3)(-) radical without affecting the unirradiated baseline. Post-irradiation annealing of wallboard prevents recuperation of the radiosensitive CO(3)(-) radical with additional irradiation. A single-aliquot additive dose procedure is developed that successfully measures test doses as low as 0.76 Gy.
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http://dx.doi.org/10.1093/rpd/ncq581DOI Listing
November 2011

Optically stimulated luminescence dosimetry with gypsum wallboard (drywall).

Radiat Prot Dosimetry 2010 Sep 6;141(1):1-9. Epub 2010 May 6.

Department of Medical Physics and Applied Radiation Sciences, McMaster University, 1280 Main St West, Hamilton, ON, Canada L9H 6L6.

Gypsum wallboard (drywall) represents an attractive target for retrospective dosimetry by optically stimulated luminescence (OSL) in the event of a radiological accident or malicious use of nuclear material. In this study, wallboard is shown to display a radiation-induced luminescence signal (RIS) as well as a natural background signal (NS), which is comparable in intensity to the RIS. Excitation and emission spectra show that maximum luminescence intensity is obtained for stimulation with blue light-emitting diodes (470 nm) and for detection in the ultraviolet region (290-370 nm). It is necessary to decrease the optical stimulation power dramatically in order to adequately separate the RIS from the interfering background signal. The necessary protocols are developed for accurately measuring the absorbed dose as low as 500 mGy and demonstrate that the RIS decays logarithmically with storage time, with complete erasure expected within 1-4 d.
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http://dx.doi.org/10.1093/rpd/ncq143DOI Listing
September 2010

Geochronology of cave deposits at Liang Bua and of adjacent river terraces in the Wae Racang valley, western Flores, Indonesia: a synthesis of age estimates for the type locality of Homo floresiensis.

J Hum Evol 2009 Nov 28;57(5):484-502. Epub 2009 Feb 28.

GeoQuEST Research Centre, University of Wollongong, NSW, Australia.

A robust timeframe for the extant cave deposits at Liang Bua, and for the river terraces in the adjoining Wae Racang valley, is essential to constrain the period of existence and time of extinction of Homo floresiensis and other biota that have been excavated at this hominin type locality. Reliable age control is also required for the variety of artifacts excavated from these deposits, and to assist in environmental reconstructions for this river valley and for the region more broadly. In this paper, we summarize the available geochronological information for Liang Bua and its immediate environs, obtained using seven numerical-age methods: radiocarbon, thermoluminescence, optically- and infrared-stimulated luminescence (collectively known as optical dating), uranium-series, electron spin resonance, and coupled electron spin resonance/uranium-series. We synthesize the large number of numerical age determinations reported previously and present additional age estimates germane to questions of hominin evolution and extinction.
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http://dx.doi.org/10.1016/j.jhevol.2009.01.003DOI Listing
November 2009

Dating the demise: neandertal extinction and the establishment of modern humans in the southern Caucasus.

J Hum Evol 2008 Nov 18;55(5):817-33. Epub 2008 Oct 18.

Department of Anthropology, 354 Mansfield Road, Unit 2176, University of Connecticut, Storrs, CT 06269-2176, USA.

This paper considers the recent radiometric dating (14C-AMS, TL, ESR) of 76 late Middle and early Upper Paleolithic samples from Ortvale Klde Rockshelter, located in the Republic of Georgia. We present a critical evaluation of each date based on its stratigraphic and archaeological context, its pretreatment and contamination history, and its resulting accuracy and precision, the goal being to establish a sound chronology for the site. Only by systematically identifying aberrant dates within a data set and isolating them from further analysis can we hope to understand cultural and biological phenomena on an accurate temporal scale. Based on the strict discard protocol outlined here, we omit 25% of the dated samples from the analysis. The remaining data speak to the lengthy tenure of Neandertals in the region, but also to their relatively rapid demise and the establishment of modern human populations approximately 38-34 ka 14C BP (42-39 kacalBP(Hulu)). We compare these chronometric data with those from the neighboring sites of Bronze and Dzudzuana caves, as well as Mezmaiskaya Cave, located in the northern Caucasus. While the lack of key contextual information limit our ability to subject these other data sets to the same critical evaluation procedure, they provide the first interregional temporal assessment of the Middle to Upper Paleolithic "transition," the results of which suggest an initial expansion of modern humans into the southern Caucasus followed by expansion along the Black Sea coast and into the northern Caucasus.
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http://dx.doi.org/10.1016/j.jhevol.2008.08.010DOI Listing
November 2008

The Pech-de-l'Azé I Neandertal child: ESR, uranium-series, and AMS 14C dating of its MTA type B context.

J Hum Evol 2007 Apr 10;52(4):455-66. Epub 2006 Dec 10.

Max Planck Institute for Evolutionary Anthropology, Dept. of Human Evolution, Deutscher Platz 6, D-04103 Leipzig, Germany.

The Pech-de-l'Azé I skull and mandible are included in the juvenile Neandertal remains from Europe. However, some preserved features in the cranial skeleton seem to distinguish the specimen from other Neandertal children. Unfortunately, the stratigraphic position and dating of this child has never been clear. Our recent work on unpublished archives show that the Pech-de-l'Azé I Neandertal child was discovered at the bottom of layer 6, attributed to the Mousterian of Acheulean tradition type B. These skull and mandible are the first diagnostic human remains (aside from an isolated tooth) attributed to the Mousterian of Acheulian tradition (MTA) type B. Consequently, we confirm that Neandertals were the makers of this Mousterian industry, which is characterized by unusual high frequencies of Upper Paleolithic type tools, elongated blanks and blades. We were able to date the context of the hominid remains by dating layer 6 and the layers above and beneath it using ESR, coupled ESR/(230)Th/(234)U (coupled ESR/U-series), and AMS (14)C. Coupled ESR/U-series results on 16 mammalian teeth constrain the age of the uppermost layer 7 to 41-58ka, and layer 6 to 37-51ka. The wide spread in each age estimate results mainly from uncertainties in the gamma-dose rate. These ages are concordant with AMS (14)C ages of two bones coming from the top of layer 6, which provide dates of about 41.7-43.6ka cal BP. A combination of stratigraphic arguments and dating results for layers 6 and 7 show that the Neandertal child cannot be older than 51ka or younger than 41ka. The lowermost layer 4 is shown to be older than 43ka by the principle of superposition and ESR dating in the immediately overlying layer 5. This study shows that the MTA type B had been manufactured by Neandertals before the arrival of anatomically modern humans in the local region. Additionally, by providing a firm chronological framework for the specific morphometric the features of Pech-de-l'Azé I Neandertal child, this study is a new step toward the understanding of temporal and spatial changes in the ontogenesis of Neandertals in south-western Europe during oxygen isotope stages 5-3.
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http://dx.doi.org/10.1016/j.jhevol.2006.11.006DOI Listing
April 2007

Retrospective radiation dosimetry using electron paramagnetic resonance in canine dental enamel.

Appl Radiat Isot 2005 Feb;62(2):173-9

Medical Physics & Applied Radiation Sciences, McMaster University, 1280 Main Street West, Hamilton, ON, Canada, L8S 4M1.

Electron paramagnetic resonance (EPR) biodosimetry of human tooth enamel has been widely used for measuring radiation doses in various scenarios. We have now developed EPR dosimetry in tooth enamel extracted from canines. Molars and incisors from canines were cleaned by processing in supersaturated aqueous potassium hydroxide solution. The dosimetric signal in canine tooth enamel was found to increase linearly as a function of laboratory added dose from 0.44+/-0.02 to 4.42+/-0.22 Gy. The gamma radiation sensitivity of the canine molar enamel was found to be comparable to that of human tooth enamel. The dosimetric signal in canine enamel has been found to be stable up to at least 6 weeks after in vitro irradiation. A dosimetric signal variation of 10-25% was observed for canines ranging from in age 3 years to 16 year old.
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http://dx.doi.org/10.1016/j.apradiso.2004.08.031DOI Listing
February 2005

Archaeology and age of a new hominin from Flores in eastern Indonesia.

Nature 2004 Oct;431(7012):1087-91

Archaeology and Palaeoanthropology, School of Human and Environmental Studies, University of New England, Armidale, New South Wales 2351, Australia.

Excavations at Liang Bua, a large limestone cave on the island of Flores in eastern Indonesia, have yielded evidence for a population of tiny hominins, sufficiently distinct anatomically to be assigned to a new species, Homo floresiensis. The finds comprise the cranial and some post-cranial remains of one individual, as well as a premolar from another individual in older deposits. Here we describe their context, implications and the remaining archaeological uncertainties. Dating by radiocarbon (14C), luminescence, uranium-series and electron spin resonance (ESR) methods indicates that H. floresiensis existed from before 38,000 years ago (kyr) until at least 18 kyr. Associated deposits contain stone artefacts and animal remains, including Komodo dragon and an endemic, dwarfed species of Stegodon. H. floresiensis originated from an early dispersal of Homo erectus (including specimens referred to as Homo ergaster and Homo georgicus) that reached Flores, and then survived on this island refuge until relatively recently. It overlapped significantly in time with Homo sapiens in the region, but we do not know if or how the two species interacted.
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http://dx.doi.org/10.1038/nature02956DOI Listing
October 2004

Later Middle Pleistocene human remains from the Almonda Karstic system, Torres Novas, Portugal.

J Hum Evol 2003 Sep;45(3):219-26

Department of Anthropology, Campus Box 1114, Washington University, St. Louis, MO 63130, USA.

Later Middle Pleistocene archeological deposits of the Galeria Pesada (Gruta da Aroeira), Almonda Karstic System, Torres Novas, Portugal, yielded two archaic human teeth, a mandibular canine and a maxillary third molar. The C(1)presents moderate and asymmetrical shoveling with a stout root. The slightly worn M(3)exhibits at least four cusps with a large hypocone, three roots with large radicular plates, and an absence of taurodontism. They are moderately large for later Middle Pleistocene humans in their buccolingual crown diameters, although the M(3)mesiodistal diameter is modest. The C(1)exhibits labial calculus and multiple linear hypoplastic defects, but the M(3)is lesion free. Both teeth are morphologically similar to those of other Middle Pleistocene European humans and reinforce a pattern of dental hypertrophy among these archaic Homo.
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http://dx.doi.org/10.1016/j.jhevol.2003.07.001DOI Listing
September 2003

Biophysical dose measurement using electron paramagnetic resonance in rodent teeth.

Appl Radiat Isot 2003 Aug-Sep;59(2-3):189-96

Medical Physics and Applied Radiation Sciences, McMaster University, 1280 Main Street West, Hamilton, Ont., Canada L8S 4M1.

Electron paramagnetic resonance (EPR) dosimetry of human tooth enamel has been widely used in measuring radiation doses in various scenarios. However, there are situations that do not involve a human victim (e.g. tests for suspected environmental overexposures, measurements of doses to experimental animals in radiation biology research, or chronology of archaeological deposits). For such cases we have developed an EPR dosimetry technique making use of enamel of teeth extracted from mice. Tooth enamel from both previously irradiated and unirradiated mice was extracted and cleaned by processing in supersaturated KOH aqueous solution. Teeth from mice with no previous irradiation history exhibited a linear EPR response to the dose in the range from 0.8 to 5.5 Gy. The EPR dose reconstruction for a preliminarily irradiated batch resulted in the radiation dose of (1.4+/-0.2) Gy, which was in a good agreement with the estimated exposure of the teeth. The sensitivity of the EPR response of mouse enamel to gamma radiation was found to be half of that of human tooth enamel. The dosimetric EPR signal of mouse enamel is stable up at least to 42 days after exposure to radiation. Dose reconstruction was only possible with the enamel extracted from molars and premolars and could not be performed with incisors. Electron micrographs showed structural variations in the incisor enamel, possibly explaining the large interfering signal in the non-molar teeth.
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http://dx.doi.org/10.1016/s0969-8043(03)00166-0DOI Listing
November 2003

Quantification of low dose signal in EPR tooth dosimetry--a novel approach.

Radiat Prot Dosimetry 2003 ;103(4):359-62

Medical Physics & Applied Radiation Sciences, McMaster University, 1280 Main Street West, Hamilton, ON, Canada L8S 4M1.

For radiation exposures below 100 mGy, the dosimetric signal in tooth enamel is too small to be measured by using the traditional dose reconstruction procedure. This is because low amplitude zero-added-dose signal can not be identified in an EPR spectrometer. A technique is presented wherein, zero-added-dose signal. when amplified by a proper known dose, can be measured in the EPR spectrometer. Mathematically, the accidental dose x is modified by a known amount of exposure, y (large enough so that the signal is now visible), and total exposure becomes x' = x + y, which is the modified-zero-added dose. The exposure x' is then quantified using the conventional backward extrapolation method and the accidental dose can be measured. In a laboratory controlled experiment, the feasibility of dose reconstruction in the 100 mGy range has been demonstrated. This may enable measurements of dose even due to suspected low exposure in tooth enamel.
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http://dx.doi.org/10.1093/oxfordjournals.rpd.a006153DOI Listing
November 2003

ESR of E' centres in unstrained geological quartz grains.

Appl Radiat Isot 2002 Oct;57(4):491-6

School of Geography and Geology, McMaster University, Hamilton, Ont, Canada.

E1' centres are detectable by ESR spectroscopy in unstrained quartz extracted from weathered rock of Cretaceous age. These centres completely disappear when the samples are irradiated with an artificial gamma-dose of about 200 Gy. The concentration of E1' centres thermally (re)generated at 310 degrees C can be reduced drastically under the influence of gamma-quanta, too. The gamma-radiation induces thermally unstable components in the quartz matrices that start to decay at around 100 degrees C.
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http://dx.doi.org/10.1016/s0969-8043(01)00270-6DOI Listing
October 2002

ESR dating of the Die Kelders Cave 1 site, South Africa.

J Hum Evol 2000 Jan;38(1):121-8

School of Geography and Geology, McMaster University, Hamilton, Ontario, L8S 4M1, Canada.

ESR measurements were made on ten enamel subsamples from six teeth recovered in layers 4-5, 6, 10, and 12 in the site of Die Kelders Cave 1, South Africa. The teeth (enamel and dentine) contained significant concentrations of uranium and therefore the U uptake model has a large influence on the computed ages. Variations in moisture content in the sediment had a smaller effect on the dose rate and calculated ages. For any given model of U uptake and moisture content, all the teeth gave very similar ages, implying that the entire deposit was formed over a short interval (<10,000 y). Comparison with OSL ages for the sediments suggests that the teeth experienced early U uptake, in which case the average age of the deposit is 70+/-4 ka (assuming a moisture content of 10%). Agreement between replicate subsamples was excellent.
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http://dx.doi.org/10.1006/jhev.1999.0352DOI Listing
January 2000

Latest Homo erectus of Java: potential contemporaneity with Homo sapiens in southeast Asia.

Science 1996 Dec;274(5294):1870-4

Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, CA 94709 USA.

Hominid fossils from Ngandong and Sambungmacan, Central Java, are considered the most morphologically advanced representatives of Homo erectus. Electron spin resonance (ESR) and mass spectrometric U-series dating of fossil bovid teeth collected from the hominid-bearing levels at these sites gave mean ages of 27 +/- 2 to 53.3 +/- 4 thousand years ago; the range in ages reflects uncertainties in uranium migration histories. These ages are 20,000 to 400,000 years younger than previous age estimates for these hominids and indicate that H. erectus may have survived on Java at least 250,000 years longer than on the Asian mainland, and perhaps 1 million years longer than in Africa. The new ages raise the possibility that H. erectus overlapped in time with anatomically modern humans (H. sapiens) in Southeast Asia.
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http://dx.doi.org/10.1126/science.274.5294.1870DOI Listing
December 1996

Early Homo and associated artefacts from Asia.

Nature 1995 Nov;378(6554):275-8

Institute of Vertebrate Paleontology and Paleoanthropology, Academia Sinica, Beijing, China.

The site of Longgupo Cave was discovered in 1984 and excavated in 1985-1988 by the Institute of Vertebrate Paleontology and Paleoanthropology (Beijing) and the Chongqing National Museum (Sichuan Province). Important finds include very archaic hominid dental fragments, Gigantopithecus teeth and primitive stone tools. Palaeomagnetic analysis and the presence of Ailuropoda microta (pygmy giant panda) suggested that the hominid-bearing levels dated to the earliest Pleistocene. In 1992, joint Chinese-American-Canadian geochronological research corroborated the age using electron spin resonance (ESR) analysis. We report here that the hominid dentition and stone tools from Longgupo Cave are comparable in age and morphology with early representives of the genus Homo (H. habilis and H. ergaster) and the Oldowan technology in East Africa. The Longgupo dentition is demonstrably more primitive than that seen in Asian Homo erectus. Longgupo's diverse and well preserved Plio-Pleistocene fauna of 116 species provide a sensitive contextual base for interpreting the early arrival of the genus Homo in Asia.
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http://dx.doi.org/10.1038/378275a0DOI Listing
November 1995

ESR ages for Krapina hominids.

Nature 1995 Nov;378(6552):24

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http://dx.doi.org/10.1038/378024a0DOI Listing
November 1995

Dating and context of three middle stone age sites with bone points in the Upper Semliki Valley, Zaire.

Science 1995 Apr;268(5210):548-53

Department of Anthropology, George Washington University, Washington, DC 20052, USA.

The extent to which the earliest anatomically modern humans in Africa exhibited behavioral and cognitive traits typical of Homo sapiens sapiens is controversial. In eastern Zaire, archaeological sites with bone points have yielded dates older than 89(-15)+22 thousand years ago by several techniques. These include electron spin resonance, thermoluminescence, optically stimulated luminescence, uranium series, and amino acid racemization. Faunal and stratigraphic data are consistent with this age.
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http://dx.doi.org/10.1126/science.7725099DOI Listing
April 1995

Giant radiation-induced color halos in quartz: solution to a riddle.

Authors:
A L Odom W J Rink

Science 1989 Oct;246(4926):107-9

The radii of radiation-induced color halos(RICHs) surrounding radioactive mineral inclusions in mica generally correspond closely to the calculated range of common uranogenic and thorogenic alpha particles in mica. Many exceptions are known, however, and these variants have led investigators to some rather exotic interpretations. Three RICHs found in quartz are identified as aluminum hole-trapping centers. Whereas the inner radii of these RICHs closely match the predicted range of the most energetic common alphas(39 micrometers), the color centers observed extend to 100 micrometers. Migration of valence-band holes down a radiation-induced charge potential might account for enigmatic RICHs. Such RICHs provide natural experiments in ultraslow charge diffusion.
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http://dx.doi.org/10.1126/science.246.4926.107DOI Listing
October 1989

[Final remarks on the iris question].

Authors:
W RINK

Hippokrates 1951 Feb;22(3):77-8

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February 1951

[Possibilities and limitations of iridodiagnosis].

Authors:
W RINK

Hippokrates 1950 Sep;21(17):518-20

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September 1950