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Francesco d'Errico

Publications and source records attributed to Francesco d'Errico.

16 recordsLinked to original sources

Denisovans from southwestern China and their subsistence strategies.

Growing fossil and genomic evidence has substantially advanced our understanding of Denisovans' evolutionary history1-9, yet their technological behaviours and subsistence strategies remain poorly documented. Here we present a comprehensive analysis of hominin fossils and associated archaeological remains from Bianfu Cave, Yunnan Province, southwestern China. The hominin fossils are dated to about 167-134 thousand years ago (ka), whereas the cultural sequence spanned from about 190 ka to 70 ka, representing one of the longest cultural records most parsimoniously attributed to Denisovans-identified through enamel-dentine junction morphology and palaeoproteomic analyses10. The new fossils include four teeth that expand the known dental variation of this group, two cranial fragments and a radius. Faunal and pollen records indicate a conifer-dominated forest or forest-steppe environment across Marine Isotope Stages 6 to 4. The inhabitants of Bianfu Cave practised specialized hunting of medium- to large-bodied prey and used a technological strategy characterized by expedient core reduction and tool production, alongside pervasive use of unmodified bones. This pattern suggests an adaptive system prioritizing the exploitation of object affordance over intensive tool manufacture. Bianfu Cave provides unprecedented insights into Denisovan biology, behaviour and ecology in eastern Asia and points to a substantial genetic and cultural legacy in later populations in Southeast Asia and Oceania.

Journal Article↗

Additional evidence for bone technology in the southern African Middle Stone Age.

Few Middle Stone Age sites have yielded convincing evidence for a complex bone technology, a behavior often associated with the emergence of modern cultures. Here, we review the published evidence for Middle Stone Age bone tools from southern Africa, analyze an additional nine bone artifacts recently recovered from Middle Stone Age levels at Blombos Cave, describe an unpublished bone tool from probable Middle Stone Age levels at Peers Cave, examine a single bone awl found at Blombosch Sands (an open site near Blombos Cave), and reappraise marked bone artifacts and a bone point recovered from Klasies River. To determine the chronological and cultural attribution of these artifacts, document bone-manufacturing techniques associated with the southern African MSA, and discuss the symbolic significance of the markings present on some of these objects we use (1) available contextual information; (2) morphometric comparison of Later Stone Age, Modern San, and purported Middle Stone Age projectile points; (3) analysis of the carbon/nitrogen content of bone tools and faunal remains from Peers and Blombos caves; and (4) microscopic analysis of traces of manufacture and use. Previously undescribed bone artifacts from Blombos Cave include a massive point manufactured on weathered bone, two complete awls and two awl tips manufactured on small-sized mammal and bird bone, a probable projectile point with a tang manufactured by knapping and scraping, a shaft fragment modified by percussion, used as retoucher and bearing a set of incised lines on the middle of the periosteal surface, and two fragments with possible engravings. The point from Peers Cave can be assigned to the Middle Stone Age and bears tiny markings reminiscent of those recorded on projectile points from Blombos and used as marks of ownership on San arrow points. The awl from Blombosch Sands and the bone point from Klasies River can be attributed to the Later Stone Age. Two notched objects from Klasies are attributed to the Middle Stone Age and interpreted as tools used on soft material; a third object bears possible deliberate symbolic engravings. Although low in number, the instances of bone artifacts attributable to the Middle Stone Age is increasing and demonstrates that the bone tools from Blombos Cave are not isolated instances. New discoveries of bone tools dating to this time period can be expected.

Africa, Southern↗

Analysis of Aurignacian interstratification at the Chatelperronian-type site and implications for the behavioral modernity of Neandertals.

The Châtelperronian is a Neandertal-associated archeological culture featuring ornaments and decorated bone tools. It is often suggested that such symbolic items do not imply that Neandertals had modern cognition and stand instead for influences received from coeval, nearby early modern humans represented by the Aurignacian culture, whose precocity would be proven by stratigraphy and radiocarbon dates. The Grotte des Fées at Châtelperron (France) is the remaining case of such a potential Châtelperronian-Aurignacian contemporaneity, but reanalysis shows that its stratification is poor and unclear, the bone assemblage is carnivore-accumulated, the putative interstratified Aurignacian lens in level B4 is made up for the most part of Châtelperronian material, the upper part of the sequence is entirely disturbed, and the few Aurignacian items in levels B4-5 represent isolated intrusions into otherwise in situ Châtelperronian deposits. As elsewhere in southwestern Europe, this evidence confirms that the Aurignacian postdates the Châtelperronian and that the latter's cultural innovations are better explained as the Neandertals' independent development of behavioral modernity.

Anthropology, Physical↗

An acoustical bubble counter for superheated drop detectors.

A new bubble counter has been developed based on the well-established approach of detecting vaporization events acoustically in superheated drop detectors (SDDs). This counter is called the Framework Scientific ABC 1260, and it represents a major improvement over prior versions of this technology. By utilizing advanced acoustic pattern recognition software, the bubble formation event can be differentiated from ambient background noise, as well as from other acoustic signatures. Additional structural design enhancements include a relocation of the electronic components to the bottom of the device; thus allowing for greater stability, easier access to vial SDDs without exposure to system electronics. Upgrades in the electronics permit an increase in the speed of bubble detection by almost 50%, compared with earlier versions of the counters. By positioning the vial on top of the device, temperature and sound insulation can be accommodated for extreme environments. Lead shells can also be utilized for an enhanced response to high-energy neutrons.

Acoustics↗

Status of radiation detection with superheated emulsions.

The introduction of new approaches for neutron detection and measurements is very rare. A similar breakthrough occurred in 1979 when Robert Apfel redefined the bubble chamber concept with his invention of the superheated drop detector. Twenty-five years after the introduction of these devices, the field of radiation detection with superheated liquids is thriving. A large variety of halocarbons are employed in the formulation of detectors, and this permits a broad range of applications. These are literally pushing the superheated emulsions to their ultimate limits and they require refinements in our understanding of the detector physics. This paper reviews the physics of superheated emulsions, the related instrumentation and their applications in radiation measurements.

Dose-Response Relationship, Radiation↗

Middle Paleolithic shell beads in Israel and Algeria.

Perforated marine gastropod shells at the western Asian site of Skhul and the North African site of Oued Djebbana indicate the early use of beads by modern humans in these regions. The remoteness of these sites from the seashore and a comparison of the shells to natural shell assemblages indicate deliberate selection and transport by humans for symbolic use. Elemental and chemical analyses of sediment matrix adhered to one Nassarius gibbosulus from Skhul indicate that the shell bead comes from a layer containing 10 human fossils and dating to 100,000 to 135,000 years ago, about 25,000 years earlier than previous evidence for personal decoration by modern humans in South Africa.

Algeria↗

Dosimetric issues in radiation protection of radiotherapy patients.

As life expectancy increases, thanks to improving general medical practices, cancer treatments for the ageing population become evermore necessary. Radiation therapy is increasingly a treatment of choice, promoted by continuing improvements in dose delivery technologies. Some techniques, collectively referred to as intensity-modulated radiation therapy, are encountering widespread acceptance and implementation, promoted by reports of superior tumour control and reduced toxicity. However, these new techniques pose new challenges in terms of radiation protection of patients, as they cause a more extensive low-dose exposure of normal tissues compared with conventional radiation therapy. The related dosimetric challenges and the methods available to tackle them are reviewed in this paper, which also emphasises the need for standard radiation protection dosimetry procedures so that information may be consistently gathered for a comparative evaluation of the different treatment modalities.

Adolescent↗

Some developments in neutron and charged particle dosimetry.

There is an increasing need for dosimetry of neutrons and charged particles. Increasing exposure levels are reported in the nuclear industry, deriving from more frequent in-service entries at commercial nuclear power plants, and from increased plant decommissioning and refurbishment activities. Another need stems from the compliance with requirements of the regulations and standards. The European Council directive 96/29 requires dosimetric precautions if the effective dose exceeds 1 mSv a(-1). On average, aircrew members exceed this value. Further, there is a trend of increasing use of charged particles in radiotherapy. The present situation is that we have reasonably good photon dosemeters, but neutron and charged particle dosemeters are still in need of improvements. This work highlights some of the developments in this field. It is mainly concentrated on some developments in passive dosimetry, in particular thermally and optically stimulated luminescent detectors, indicating the direction of ongoing research. It shows that passive dosemeters are still a very active field. Active dosemeters will not be discussed with the exception of new developments in microdosimetric measurements [new types of tissue equivalent proportional counters (TEPCs)]. The TEPC is unique in its ability to provide a simultaneous determination of neutron / charged particle / gamma ray doses, or dose equivalents using a single detector.

Heavy Ions↗

Application of Gafchromic film in the dosimetry of an intravascular brachytherapy source.

The methodology of brachytherapy source dosimetry with Gafchromic MD 55-2 film (ISP Technologies, Inc.) is examined with an emphasis on the nonlinearity of the optical density-dose relation within the dynamic dose range, the radial distance-dependent measurement uncertainty, and the format of data presentation. The specific source chosen for this study was a Checkmate (Cordis Corporation) intravascular brachytherapy system. The two-dimensional dose distribution around the source was characterized by a comprehensive analysis of measurement uncertainties. A comparative analysis of the dosimetric data from the vendor and from the scientific literature showed a substantial consistency of the information available for the Checkmate source. Our two-dimensional dosimetric data for the Checkmate source trains is presented in the form of measured along and away dose tables.

Blood Vessels↗

Nassarius kraussianus shell beads from Blombos Cave: evidence for symbolic behaviour in the Middle Stone Age.

Since 1991, excavations at Blombos Cave have yielded a well-preserved sample of faunal and cultural material in Middle Stone Age (MSA) levels. The uppermost MSA phase, M1, is dated to c. 75 ka by optically stimulated luminescence (OSL) and thermoluminescence, and the middle M2 phase to a provisional c. 78 ka. Artefacts unusual in a MSA context from these phases include bifacial points, bone tools, engraved ochre and engraved bone. In this paper, we describe forty-one marine tick shell beads recovered from these MSA phases and tick shell beads from Later Stone Age (LSA) levels at Blombos Cave and the Die Kelders site. Thirty-nine shell beads come from the upper M1 phase and two from M2. Morphometric, taphonomic and microscopic analysis of modern assemblages of living and dead tick shell demonstrate that the presence of perforated Nassarius kraussianus shells in the Blombos MSA levels cannot be due to natural processes or accidental transport by humans. The types of perforation seen on the MSA shells are absent on modern accumulations of dead shells and not attributable to post-depositional damage. Their location, size, and microscopic features are similar to those obtained experimentally by piercing the shell wall, through the aperture, with a sharp bone point. Use-wear, recorded on the perforation edge, the outer lip, and the parietal wall of the aperture indicates the shells having being strung and worn. MSA shell beads differ significantly in size, perforation type, wear pattern and shade compared to LSA beads and this eliminates the possibility of mixing across respective levels. Thirty-one beads were found in four groups of five to twelve beads, each group being recovered in a single square or in two adjacent sub-squares during a single excavation day. Within a group, shells display a similar shade, use-wear pattern and perforation size suggesting their provenance from the same beadwork item, lost or disposed during a single event. The likely symbolic significance of these finds suggests levels of cognitively modern behaviour not previously associated with MSA people.

Animals↗

The newsletter 'European Research in Radiological Sciences'.

The newsletter 'European Research in Radiological Sciences' is jointly published by the European Late Effects Project Group and the European Radiation Dosimetry Group to disseminate information about research projects and activities carried out under the EURATOM Framework Programme. Since May 2003, the Newsletter is operated interactively from the Internet. The new site uses a dedicated database that automatically generates HTML pages. This system developed at the University of Cambridge provides an innovative approach to improve the dissemination of project information.

European Union↗

Passive detectors for neutron personal dosimetry: state of the art.

Passive, solid-state detectors still dominate the field of neutron personal dosimetry, mainly thanks to their low cost, high reliability and elevated throughput. However, the recent appearance in the market of several electronic personal dosemeters for neutrons presents a challenge to the exclusive use of passive systems for primary or official dosimetry. This scenario drives research and development activities on passive dosemeters towards systems offering greater accuracy of response and lower detection limits. In addition, further applications and properties of the passive detectors, which are not met by the electronic devices, are also being explored. In particular, extensive investigations are in progress on the use of solid-state detectors for aviation and space dosimetry, where high-energy neutron fields are encountered. The present situation is also stimulating an acceleration in the development of international standards on performance and test requirements for passive dosimetry systems, which can expedite significantly the implementation of techniques in commercial personal dosimetry services. Upcoming standards will cover thermoluminescence albedo dosemeters, etched-track detectors, superheated emulsions and direct ion storage chambers, attesting to the level of maturity reached by these techniques. This work reviews the developments in the field of passive neutron dosimetry emerged since the previous Neutron Dosimetry Symposium, reporting on the current status of the subject and indicating the direction of ongoing research.

Environmental Exposure↗

Dosimetric characteristics of the Novoste Beta-Cath 90Sr/Y source trains at submillimeter distances.

Measurements were performed on the 30, 40, and 60 mm 90Sr/Y beta-emitter source trains used in the Novoste Beta-Cath system to determine their dosimetric characteristics at submillimeter distances and provide the necessary TG-60 parameters for mapping their dose distributions. These measurements were carried out in a Solid Water phantom where MD55-2 Gafchromic films were placed in direct contact with a 5 French (F) catheter used for the 30 and 60 mm source trains and a 3.5F catheter used for thinner 30 and 40 mm source trains. A data set consisted of three pieces of Gafchromic film irradiated for periods of 1.5, 5, and 10 minutes, respectively. This 3-film irradiation technique provided reliable dose data at short, intermediate and long distances from a source train. Three data sets per source train were collected in this study. For the 30 mm source train with a 5F catheter, data were collected with the source axis at proximal (0.41 mm) and distal (1.19 mm) positions to the film surface in order to investigate dosimetric effects due to the off centering of the source train lumen within the catheter. Absolute doses were determined by calibrating the Gafchromic film in a high-energy electron beam from a radiotherapy accelerator. The absolute dose rates at a distance of 2 mm along the source trains transverse axis were found to be within 13.7% of the values provided by Novoste. Radial dose functions were within 13% compared to 90Sr/Y source train data constructed from Soares' 90Sr/Y single seed data and within 17% and 25% compared to Monte Carlo data by Ye et al., and Wang et al., respectively. Discrepancies of 33% and 19% were observed at short radial distances (< or = 1 mm) between the Novoste Monte Carlo and the 3.5F and 5F catheter measured data, respectively. The source off centering data showed higher dose contribution from the source train at its distal rather than proximal position. Radial dose function comparisons between the Novoste Monte Carlo and the measured data, calculated as a function of radial distance from the catheter's center showed good agreement (< or = 10%).

Brachytherapy↗

Fast high-resolution 3D segmented echo planar imaging for dose mapping using a superheated emulsion chamber.

The superheated emulsion chamber (SEC) consists of superheated droplets of halocarbons in an aqueous gel. The gel resides in a pressure chamber. Brachytherapy sources can be implanted in the SEC for radiation dosimetry studies. Upon irradiation by ionizing radiation, the metastable droplets vaporize to form microbubbles. MRI can be used to determine the distribution of bubbles following irradiation of the SEC. In order to generate sufficient statistical accuracy in the determination of dose distributions around brachytherapy sources, it is necessary to use hundreds of irradiation cycles. Susceptibility-weighted images provide contrast between the gel and the vapor microbubbles. This article describes a 3D, blipped, double-sampled, segmented echo-planar imaging technique for rapidly imaging the SEC at 650 microm isotropic 3D resolution in about 2 min. This method was used with a pressure cycling SEC to acquire hundreds of images in several hours. Results are presented showing the 2D dose distribution generated by an (125)I source as measured in the SEC using this new imaging method.

Brachytherapy↗

Emergence of modern human behavior: Middle Stone Age engravings from South Africa.

In the Eurasian Upper Paleolithic after about 35,000 years ago, abstract or depictional images provide evidence for cognitive abilities considered integral to modern human behavior. Here we report on two abstract representations engraved on pieces of red ochre recovered from the Middle Stone Age layers at Blombos Cave in South Africa. A mean date of 77,000 years was obtained for the layers containing the engraved ochres by thermoluminescence dating of burnt lithics, and the stratigraphic integrity was confirmed by an optically stimulated luminescence age of 70,000 years on an overlying dune. These engravings support the emergence of modern human behavior in Africa at least 35,000 years before the start of the Upper Paleolithic.

Aluminum Silicates↗