Neanderthal Use of Animal Bones as Retouchers at the Level XV of the Sopeña Rock Shelter (Asturias, Northern Spain)

[Abstract] Bone retouchers are a technological appliance used to perfect lithic tools efficiently. They are most frequently found in Middle Palaeolithic contexts. In this paper, we present a group of bone retouchers from the Mousterian Level XV of the Sopeña rock shelter (Asturias, Spain). The bone part preferred was the middle part of the shaft of long bones: Most of them are on metacarpals, followed by metatarsals, femurs, and tibias. The most used animal species is adult red deer. These retouchers have either one, two, or three active areas, with a central disposition. The impact marks are close together; oval pits are common, as well as straight, sinuous, and irregular grooves. The surfaces on these marks appear pitted and scaled. There are indications that the bones employed were relatively fresh. The length, width, and thickness of those bone fragments seem to be the determining factor when choosing them to be used as retouchers in the process of finishing lithic tools. The formats documented in Sopeña Level XV are similar to those found in other Mousterian sites in Iberia, although there is a certain variability regarding their width. The Neanderthals of Sopeña acquired the raw material for these retouchers from the faunal remains generated in the process of butchering and eating the animals. These retouchers were used as implements to perfect lithic tools made mainly on quartzite, and they were used repeatedly and maybe for a long time.AJR has a Postdoctoral Contract for Access to the Spanish System of Science, Technology and Innovation (Margarita Salas Grants) (MARSA 21/16) at the University of the Basque Country (UPV/EHU). The present article is part of the project “PALEOCROSS: Territorio y movilidad durante el Paleolítico superior en la Encrucijada vasca” (PID2021-126937NB-I00) (Spanish Ministry of Science). AJR is part of the Prehistory research group at the University of the Basque Country (UPV/EHU) (IT-622-13). Excavations at Sopeña were made possible by several grants to ACPLL by the following and all are gratefully acknowledged: Spanish Ramón y Cajal Program, National Geographic Society (CRE), Wenner-Gren Foundation, Institute of Human Origins (ASU), and Wings World Quest Foundatio

Raman scattering by longitudinal optical phonons in InN nanocolumns grown on Si(111) and Si(001) substrates

Raman measurements in high-quality InN nanocolumns and thin films grown on both Si(1 1 1) and Si(1 0 0) substrates display a low-energy coupled LO phonon–plasmon mode together with uncoupled longitudinal optical (LO) phonons. The coupled mode is attributed to the spontaneous accumulation of electrons on the lateral surfaces of the nanocolumns, while the uncoupled ones originates from the inner part of the nanocolumns. The LO mode in the columnar samples appears close to the E1(LO) frequency. This indicates that most of the incident light is entering through the lateral surfaces of the nanocolumns, resulting in pure longitudinal–optical mode with quasi-E1 symmetry. For increasing growth temperature, the electron density decreases as the growth rate increases. The present results indicate that electron accumulation layers do not only form on polar surfaces of InN, but also occur on non-polar ones. According to recent calculations, we attribute the electron surface accumulation to the temperature dependent In-rich surface reconstruction on the nanocolumns sidewalls

GaN and InN nanowires grown by MBE: a comparison

Morphological, optical and transport properties of GaN and InN nanowires grown by molecular beam epitaxy (MBE) have been studied. The differences between the two materials in respect to growth parameters and optimization procedure was stressed. The nanowires crystalline quality has been investigated by means of their optical properties. A comparison of the transport characteristics was given. For each material a band schema was shown, which takes into account transport and optical features and is based on Fermi level pinning at the surface.Comment: 5 pages, 5 figure

Plasma mitochondrial DNA levels are inversely associated with HIV-RNA levels and directly with CD4 counts: potential role as a biomarker of HIV replication

[Abstract] Objectives. To evaluate plasma mitochondrial DNA (mtDNA) levels among HIV-infected patients and its potential role as a biomarker of residual viral replication. Methods. HIV-infected patients on follow-up at a reference hospital in north-west Spain were selected. DNA was isolated from plasma samples and mtDNA levels were assessed using a quantitative real-time PCR assay. HIV-RNA levels and CD4+ cell counts were evaluated in the same blood samples used for plasma mtDNA quantification. Epidemiological and clinical variables were included for the analysis. Results. A total of 235 HIV-infected patients were included. Mean plasma mtDNA levels were 217 ± 656 copies/μL for naive (31.9%) and 364 ± 939 copies/μL for HIV-infected patients receiving ART and with suppressed viraemia (P = 0.043). Among the latter, mean plasma mtDNA levels were 149 ± 440 copies/μL for those with low-level viraemia (LLV; HIV-RNA 20–200 copies/mL), 265 ± 723 copies/μL for those with detected-not-quantified (DNQ) viraemia (HIV-RNA <20 copies/mL) and 644 ± 1310 copies/μL for those with not-detected (ND) viraemia. Of note, a linear trend (P = 0.006) was observed among virologically suppressed (LLV, DNQ and ND) patients. ND patients had higher mtDNA levels compared with LLV patients (P = 0.057). Moreover, mtDNA levels were inversely associated with HIV-RNA levels (Spearman’s rho −0.191, P = 0.003) and directly associated with CD4+ counts (Spearman’s rho 0.131, P = 0.046). Conclusions. Increased plasma mtDNA levels are associated with lower HIV-RNA levels and higher CD4+ cell counts. Among ART-suppressed patients, mtDNA levels were significantly higher in those with complete virological suppression (ND) than in those with LLV. These data suggest that plasma mtDNA levels might serve as a biomarker of residual HIV replication.Instituto de Salud Carlos III; CPII14/00014Instituto de Salud Carlos III; PI10/02166Instituto de Salud Carlos III; PI13/02266Instituto de Salud Carlos III; FI14/00557Instituto de Salud Carlos III; CM15/00233Instituto de Salud Carlos III; PI16/02159Instituto de Salud Carlos III; MV16/02159Instituto de Salud Carlos III; PTA2013-8277-

Quasiparticle tunnel electroresistance in superconducting junctions

The term tunnel electroresistance (TER) denotes a fast, non-volatile, reversible resistance switching triggered by voltage pulses in ferroelectric tunnel junctions. It is explained by subtle mechanisms connected to the voltage-induced reversal of the ferroelectric polarization. Here we demonstrate that effects functionally indistinguishable from the TER can be produced in a simpler junction scheme-a direct contact between a metal and an oxide-through a different mechanism: a reversible redox reaction that modifies the oxide's ground-state. This is shown in junctions based on a cuprate superconductor, whose ground-state is sensitive to the oxygen stoichiometry and can be tracked in operando via changes in the conductance spectra. Furthermore, we find that electrochemistry is the governing mechanism even if a ferroelectric is placed between the metal and the oxide. Finally, we extend the concept of electroresistance to the tunnelling of superconducting quasiparticles, for which the switching effects are much stronger than for normal electrons. Besides providing crucial understanding, our results provide a basis for non-volatile Josephson memory devices. The non-volatile switching of tunnel electroresistance in ferroelectric junctions provides the basis for memory and neuromorphic computing devices. Rouco et al. show tunnel electroresistance in superconductor-based junctions that arises from a redox rather than ferroelectric mechanism and is enhanced by superconductivity

Oxygen photo-adsorption related quenching of photoluminescence in group-III nitride nanocolumns

GaN and InGaN nanocolumns of various compositions are studied by room-temperature photoluminescence (PL) under different ambient conditions. GaN nanocolumns exhibit a reversible quenching upon exposure to air under constant UV excitation, following a t−1/2 time dependence and resulting in a total reduction of intensity by 85–90%, as compared to PL measured in vacuum, with no spectral change. This effect is not observed when exposing the samples to pure nitrogen. We attribute this effect to photoabsorption and photodesorption of oxygen that modifies the surface potential bending. InGaN nanocolumns, under the same experimental conditions do not show the same quenching features: The high-energy part of the broad PL line is not modified by exposure to air, whereas a lower-energy part, which does quench by 80–90%, can now be distinguished. We discuss the different behaviors in terms of carrier localization and possible composition or strain gradients in the InGaN nanocolumns

Understanding the selective area growth of GaN nanocolumns by MBE using Ti nanomasks

The influence of the substrate temperature, III/V flux ratio, and mask geometry on the selective area growth of GaN nanocolumns is investigated. For a given set of growth conditions, the mask design (diameter and pitch of the nanoholes) is found to be crucial to achieve selective growth within the nanoholes. The local III/V flux ratio within these nanoholes is a key factor that can be tuned, either by modifying the growth conditions or the mask geometry. On the other hand, some specific growth conditions may lead to selective growth but not be suitable for subsequent vertical growth. With optimized conditions, ordered GaN nanocolumns can be grown with a wide variety of diameters. In this work, ordered GaN nanocolumns with diameter as small as 50 nm are shown

Effect of different buffer layers on the quality of InGaN layers grown on Si

This work studies the effect of four different types of buffer layers on the structural and optical properties of InGaN layers grown on Si(111) substrates and their correlation with electrical characteristics. The vertical electrical conduction of n-InGaN/buffer-layer/p-Si heterostructures, with In composition near 46%, which theoretically produces an alignment of the bands, is analyzed. Droplet elimination by radical-beam irradiation was successfully applied to grow high quality InGaN films on Si substrates for the first time. Among several buffer choices, an AlN buffer layer with a thickness above 24 nm improves the structural and optical quality of the InGaN epilayer while keeping a top to bottom ohmic behavior. These results will allow fabricating double-junction InGaN/Si solar cells without the need of tunnel junctions between the two sub-cells, therefore simplifying the device design