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Experiments showed that multiwalled carbon nanotubes (MWCNT) can be used as masks against irradiation to create metallic nanowires in a substrate. In order to understand the limitations of this application, it is interesting to know the energy and number of carbon atoms emerging from the MWCNT after the irradiation and how the structure of the MWCNT is modified. Using a molecular dynamics code that we have previously developed, we have simulated the continuous irradiation of MWCNT with carbon and argon projectiles. We have obtained that the use of carbon instead of argon to irradiate the MWCNT increases de effectiveness of the MWCNTs as masks, due to the ability of the carbon projectiles to be part of the MWCNT structure and partially mend the damage produced during irradiation. We have analyzed the number, energy, and spatial distribution of the recoils generated during irradiation and the change of the MWCNT structure as a function of the incident energy (100 and 500 eV), fluence (up to 4.5 · 10 15 ions / cm 2 ), and number of shells (up to 5-shells) of the MWCNT. These results determine the effectiveness of MWCNT as a mask, being useful to understand whether the atoms emerging from the MWCNT produce damage in the substrate or not. We find that for carbon projectiles the efficiency of MWCNT as masks does not depend much on the fluence, but on the number of nanotube shells and projectile incident energy. On the other hand, for a given nanotube and fluence, we observe a threshold incident energy below which the nanotube acts as a perfect mask. [ABSTRACT FROM AUTHOR]

The idea of using carbon nanotubes (CNTs) as masks against irradiation has recently emerged, because of the region of a given material covered by a CNT can be protected from the effects of irradiation, creating nanowires. In this case, it is interesting to know in detail the number of generated recoils and their energy. In order to obtain these data, we simulate the irradiation of CNTs with carbon ions using a molecular dynamics code. To describe the interaction between carbon ions we use the Brenner potential joined smoothly to the Universal ZBL potential at short distances. We have analyzed the energy distributions of the carbon atoms emerging from the CNT for single projectile irradiation with incident energies from 30 eV to 5 keV. Our results show that the number and the energy of the recoil carbon atoms emerging from the CNT increases with the projectile incident energy. In average, each projectile with incident energy of 1 keV produces ∼3.6 recoils, which have a mean energy of 150 eV, while projectiles with 5 keV produce ∼7 recoils with a mean energy of 400 eV. [ABSTRACT FROM AUTHOR]

Abstract: We simulate the irradiation of carbon nanotubes (CNT) with carbon ions using a molecular dynamics code. In order to describe the interaction between carbon ions we use the Tersoff or Brenner potential, both joined smoothly to the Universal ZBL potential at short distances. We have analyzed the defects produced after irradiation, the subsequent modification of the CNT structure, and their dependence on the used interatomic potential, the projectile energy (from 10 eV to 5keV) and the dose. For single projectile irradiation, we have obtained that the coordination defect number increases with the projectile energy, although a saturation value is achieved at high projectile energies (∼3keV). For continuous projectile irradiation, we have observed that for low energies (∼10eV) the accumulation of adatoms produces a bump in the irradiated region. However, at intermediate energies (∼100eV) the irradiation produces vacancies which are healed through non-hexagonal rings. This gives rise to a shrinking of the CNT diameter in the irradiated region. Finally, if the projectile energy is high enough (∼1keV) the continuous irradiation produces the breaking of the CNT. [Copyright &y& Elsevier]

Abstract: The electronic energy loss of swift H and He ions in solid Ag is studied theoretically within the dielectric formalism, considering the different equilibrium charge states of the projectile inside the target. Excitation of the weakly-bound (outer) electrons is described by a superposition of Mermin-type energy-loss functions, whereas the contribution to the projectile energy loss due to the ionization of the K, L and M shells of the Ag atoms is included through hydrogenic or numerical generalized oscillator strengths. This method is used to evaluate the stopping power and the energy-loss straggling parameter of H and He ions in Ag as a function of the projectile energy, showing a good agreement with available experimental data. The contribution of the target inner-shells to the energy loss begins to be appreciable at projectile energies larger than a few hundred keV/u, being more important for the energy-loss straggling parameter than for the stopping cross section. [Copyright &y& Elsevier]

Abstract: We calculate the electronic energy loss of swift H+ and He+ ion beams in several solids with applications in material science and microelectronics, namely Ti, Fe, Ge, Pd, LiF and Si3N4. Our calculations are based on the dielectric formalism, where the charge density of the projectile is described by the Brandt–Kitagawa model, with the addition of projectile polarization. We take into account the different charge states of the projectile inside the target and the energy loss due to electron capture and loss processes. Using a realistic description of the target energy loss function, we obtain results that show a good agreement with available experimental data in a wide range of projectile energies. [Copyright &y& Elsevier]

Abstract: We have theoretically studied the electronic stopping cross section and the energy loss straggling of swift light ions (H+ and He+) moving through several compound semiconductors (GaAs, ZnSe, InP and SiC) as a function of the incident projectile energy. The calculations have been done using the dielectric formalism, in which the electronic structure of the projectile is described by the modified Brandt–Kitagawa model and the energy loss function (ELF) of the semiconductors is obtained using a linear combination of Mermin-type ELF to describe the outer electron excitations and generalized oscillator strengths to take into account the excitations of the inner-shell electrons. The different charge states that the projectile can acquire during its travel through the solid, as a result of electronic capture and loss processes, has been also considered. The contributions to the projectile energy loss from both the outer- and the inner-shell electron excitations are analyzed. The comparison of our calculated stopping cross sections with available experimental data shows a good agreement in a wide range of incident projectile energies. [Copyright &y& Elsevier]

The increased availability of quality genomic data has greatly improved the scope and resolution of our understanding of the recent evolutionary history of wild species adapted to extreme environments and their susceptibility to anthropogenic impacts. The guanaco (Lama guanicoe), the largest wild ungulate in South America, is a good example. The guanaco is well adapted to a wide range of habitats, including the Sechura Desert, the high Andes Mountains to the north, and the extreme temperatures and conditions of Navarino Island to the south. Guanacos also have a long history of overexploitation by humans. To assess the evolutionary impact of these challenging habitats on the genomic diversity, we analyzed 38 genomes (∼10 to 16×) throughout their extensive latitudinal distribution from the Sechura and Atacama Desert to southward into Tierra del Fuego Island. These included analyses of patterns of unique differentiation in the north and geographic region further south with admixture among L. g. cacsilensis and L. g. guanicoe. Our findings provide new insights on the divergence of the subspecies ∼800,000 yr BP and document two divergent demographic trajectories and to the initial expansion of guanaco into the more southern portions of the Atacama Desert. Patagonian guanacos have experienced contemporary reductions in effective population sizes, likely the consequence of anthropogenic impacts. The lowest levels of genetic diversity corresponded to their northern and western limits of distribution and some varying degrees of genetic differentiation. Adaptive genomic diversity was strongly linked with environmental variables and was linked with colonization toward the south followed by adaptation. [ABSTRACT FROM AUTHOR]

The article reports that forensic techniques for the investigation of crime scenes involved in the poaching of vicuña Vicugna vicugna species will be developed in Chile as a result of increase in hunting occuring on the Andean altiplano. Topics discussed include confiscation of ivory such as furs from smugglers in Chile and the training provided to several officials such as Chilean Police officers in crime scene investigation at the U.S National Fish and Wildlife Forensic Laboratory.

Comparative phylogeography describes the patterns of evolutionary divergence and whether or not they are congruent, in co-distributed populations of different taxa. If the populations of these taxa have been co-distributed for a prolonged time, and if the times between processes of perturbation or vicariance have been more or less stable, it is expected that patterns of divergence will be congruent in closely related species, for example because of similar biological and demographic characteristics. Liolaemus pictus and L. cyanogaster are widely co-distributed lizard species in southern Chile, occurring in a region with a complex topology. We analyzed the phylogeographic structure of the two lizard species using Cytochrome b DNA sequences to estimate their genetic structure in response to historical events. Our results suggest an evolutionary pattern of genetic diversity for each species that is consistent with the geomorphological history of the region, suggesting a complex phylogeographic history in Liolaemus species. Also, the high levels of divergence among haplotypes in several populations suggest the possibility that their origin might predate the middle Pleistocene in both species. Finally, our results are consistent with our hypothesis that two species have responded to historical events in parallel, where historical process have been sufficient to influence their phylogeographical structure (0.80 congruency between topologies). [ABSTRACT FROM AUTHOR]

Niche description and differentiation at broad geographic scales have been recent major topics in ecology and evolution. Describing the environmental niche structure of sister taxa with known evolutionary trajectories stands out as a useful exercise in understanding niche requirements. Here we model the environmental niche structure and distribution of the recently resolved phylogeography of guanaco (Lama guanicoe) lineages on the western slope of the southern Andes. Using a maximum entropy framework, field data, and information on climate, topography, human density, and vegetation cover, we identify differences between the two subspecies (L.g.cacsilensis, L.g.guanicoe) and their intermediate-hybrid lineage, that most likely determine the distribution of this species. While aridity seems to be a major factor influencing the distribution at the species-level (annual precipitation <900 mm), we also document important differences in niche specificity for each subspecies, where distribution of Northern lineage is explained mainly by elevation (mean = 3,413 m) and precipitation seasonality (mean = 161 mm), hybrid lineage by annual precipitation (mean = 139 mm), and Southern subspecies by annual precipitation (mean = 553 mm), precipitation seasonality (mean = 21 mm) and grass cover (mean = 8.2%). Among lineages, we detected low levels of niche overlap: I (Similarity Index) = 0.06 and D (Schoener’s Similarity Index) = 0.01; and higher levels when comparing Northern and Southern subspecies with hybrids lineage (I = 0.32-0.10 and D = 0.12-0.03, respectively). This suggests that important ecological and/or evolutionary processes are shaping the niche of guanacos in Chile, producing discrepancies when comparing range distribution at the species-level (81,756 km2) with lineages-level (65,321 km2). The subspecies-specific description of niche structure is provided here based upon detailed spatial distribution of the lineages of guanacos in Chile. Such description provides a scientific tool to further develop large scale plans for habitat conservation and preservation of intraspecific genetic variability for this far ranging South American camelid, which inhabits a diversity of ecoregion types from Andean puna to subpolar forests. [ABSTRACT FROM AUTHOR]

The irradiation of carbon based nanostructures with ions and electrons has been shown to be an appropriate tool to tailor their properties. The defects induced in the nanostructures during irradiation are able to modify their mechanical and electronic properties. Here we simulate the irradiation of carbon nanotubes with carbon ions using a molecular dynamics code. We use the Tersoff potential joined smoothly to the Universal Ziegler-Biersack-Littmark potential at short distances. We study the number of defects produced after irradiation with a single carbon ion finding a saturation with its energy at ∼ 3 keV. We observe, after continuum irradiation with low energy ions, the formation of bumps in the irradiated region. For larger energy ions we find that the diameter of the nanotube shrinks as shown in previous works. (© 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

Comparative phylogeography describes the patterns of evolutionary divergence and whether or not they are congruent, in co-distributed populations of different taxa. If the populations of these taxa have been co-distributed for a prolonged time, and if the times between processes of perturbation or vicariance have been more or less stable, it is expected that patterns of divergence will be congruent in closely related species, for example because of similar biological and demographic characteristics. Liolaemus pictus and L. cyanogaster are widely co-distributed lizard species in southern Chile, occurring in a region with a complex topology. We analyzed the phylogeographic structure of the two lizard species using Cytochrome b DNA sequences to estimate their genetic structure in response to historical events. Our results suggest an evolutionary pattern of genetic diversity for each species that is consistent with the geomorphological history of the region, suggesting a complex phylogeographic history in Liolaemus species. Also, the high levels of divergence among haplotypes in several populations suggest the possibility that their origin might predate the middle Pleistocene in both species. Finally, our results are consistent with our hypothesis that two species have responded to historical events in parallel, where historical process have been sufficient to influence their phylogeographical structure (0.80 congruency between topologies). [ABSTRACT FROM AUTHOR]

Background: The endometrium is a dynamic tissue whose changes are driven by the ovarian steroidal hormones. Its main function is to provide an adequate substrate for embryo implantation. Using microarray technology, several reports have provided the gene expression patterns of human endometrial tissue during the window of implantation. However it is required that biological connections be made across these genomic datasets to take full advantage of them. The objective of this work was to perform a research synthesis of available gene expression profiles related to acquisition of endometrial receptivity for embryo implantation, in order to gain insights into its molecular basis and regulation. Methods: Gene expression datasets were intersected to determine a consensus endometrial receptivity transcript list (CERTL). For this cluster of genes we determined their functional annotations using available web-based databases. In addition, promoter sequences were analyzed to identify putative transcription factor binding sites using bioinformatics tools and determined over-represented features. Results: We found 40 up- and 21 down-regulated transcripts in the CERTL. Those more consistently increased were C4BPA, SPP1, APOD, CD55, CFD, CLDN4, DKK1, ID4, IL15 and MAP3K5 whereas the more consistently decreased were OLFM1, CCNB1, CRABP2, EDN3, FGFR1, MSX1 and MSX2. Functional annotation of CERTL showed it was enriched with transcripts related to the immune response, complement activation and cell cycle regulation. Promoter sequence analysis of genes revealed that DNA binding sites for E47, E2F1 and SREBP1 transcription factors were the most consistently over-represented and in both up- and down-regulated genes during the window of implantation. Conclusions: Our research synthesis allowed organizing and mining high throughput data to explore endometrial receptivity and focus future research efforts on specific genes and pathways. The discovery of possible new transcription factors orchestrating the CERTL opens new alternatives for understanding gene expression regulation in uterine function. [ABSTRACT FROM AUTHOR]

The aim of this study is to evaluate if screen time and parents' education levels are associated with adherence to a Mediterranean dietary pattern. This cross-sectional study analyzed a representative sample of 3333 children and adolescents (8 to 16 years) included in the Physical Activity, Sedentarism, lifestyles and Obesity in Spanish youth (PASOS) study in Spain (which ran from March 2019 to February 2020). Data on screen time (television, computer, video games, and mobile phone) per day, Mediterranean diet adherence, daily moderate or vigorous physical activity, and parents' education levels were gathered using questionnaires. A descriptive study of the variables according to sex and parents' education level was performed. Logistic regression models (adjusted by sex and weight status) were fitted to evaluate the independent association between screen time and Kids' level of adherence to the Mediterranean diet (KIDMED) index, as well as some of its items. A greater amount of screen time was associated with worse adherence to the Mediterranean diet; a lower consumption of fruit, vegetables, fish, legumes, and nuts; and a greater consumption of fast food, sweets, and candies. A lower parents' education level was associated with worse adherence to the Mediterranean diet. It is necessary to promote the responsible, limited use of screen time, especially in children with parents with a lower education level. [ABSTRACT FROM AUTHOR]

Background: Endometrial function is essential for embryo implantation. The aim of this study was to analyze gene expression profiles from individual endometrial samples obtained from women with repeated implantation failure after IVF in oocyte donation programs. Methods: Seventeen volunteers were recruited: women who had previously participated as recipients in oocyte donation cycles and repeatedly exhibited implantation failure (Group A, study group, n = 5) or had at least one successful cycle (Group B, control group, n = 6) and spontaneously fertile women (Group C, normal fertility group, n = 6). An endometrial cycle was induced with exogenous estradiol (E2) and progesterone (P) and an endometrial sample was collected on the seventh day of P treatment. Results: Transcriptome analysis showed 82 genes with consistent differential gene expression when comparing A vs. B and A vs. C. One hundred transcripts differentially expressed in group A vs. B have been shown to be regulated by P, suggesting compromised P signaling in the endometrium. The P receptor (PR) mutation PROGINS was not detected in women from group A. Semi-quantitation of immunoreactive PRA/B, PRB and Sp1 (a transcription factor related to P signaling) in paraffin-embedded endometrial sections, did not show statistically significant differences amongst groups. However immunostaining glycodelin was significantly decreased in endometrial samples from group A Conclusions: We conclude that some cases of repeated implantation failure could be associated with an aberrant gene expression profile. Compromised P signaling might be the underlying mechanism for such endometrial gene expression deregulation in women with repeated implantation failure. [ABSTRACT FROM AUTHOR]

Abstract: We present the results of a palaeogenetic analysis of two Late Pleistocene camelids originating in southern Chile. Our analysis of two mitochondrial DNA fragments (control region and cytochrome b gene) reveals that these specimens do not belong to an extinct taxon, but rather to extant vicuña (Vicugna vicugna), whose modern distribution is restricted to the extreme elevations of the Andes, more than 3500km to the north of where these specimens originated. Our results also suggest fossil specimens from Patagonia that are currently assigned to the extinct taxon Lama gracilis, may actually belong to V. vicugna, implying a continuous distribution of the latter from the southern tip of South America to the Andes during the Final Pleistocene. The haplotypes of both specimens are not present in modern populations, suggesting a loss of genetic diversity concomitant with the contraction of the vicuña geographical distribution during the Final Pleistocene or early Holocene. [Copyright &y& Elsevier]

Self-perceived health has been used as a good estimator of health status and receiving affection can be a determining factor for good self-perceived health. The aim of the present study was to assess whether lack of social support (measured through Duke scale, which ranges from 11 to 55) was associated with poorer health status measured as self-perceived health, and whether that association was different between women and men. A cross-sectional study was conducted using data from the 2017 Spanish National Health Survey. A descriptive study was performed, and logistic regression models were applied using self-perceived health as a dependent variable. Mean Duke score was 47.6 for men and 47.9 for women (p = 0.016). Moreover, 36.3% of women and 27.6% of men reported poor self-perceived health (p < 0.001). The multivariate analysis revealed that lower scores in Duke-UNC social support scale were associated with poorer health status. That association was higher in women than in men. Poor self-perceived health was also associated with low level of education and obesity, especially among women. There was gender inequality as regards health status associated with lack of social support. These results can help design prevention strategies to improve health. [ABSTRACT FROM AUTHOR]

Selective breeding of the guanaco and vicuña indisputably led to the domestic llama and alpaca. However, the place, time and process of domestication remain poorly documented, exacerbated by increased evidence of historic and recent introgression among both domestic populations, especially those involving alpaca. Here, we report the first comprehensive assessment of patterns of microsatellite variation of 13 polymorphic microsatellites in 797 individuals representing 4 species and 2 subspecies to estimate historic and ongoing patterns of gene flow. Our results confirm that llamas were domesticated almost exclusively from the northern subspecies of guanaco (Lama guanicoe cacsilensis), but cluster analyses did not support previous findings that alpacas are solely derived from the northern subspecies of vicuña (Vicugna mensalis), with some more-recent admixture with southern populations. We also confirmed continued gene flow between llama and alpaca, and found evidence for crosses between presumably feral llamas and guanacos in northern Chile. Our results highlight the need to develop and test more-accurate markers and tools for assessing the genetic heritage of individuals, to link phenotypic variation with genetic ancestry, and to conserve historic patterns of unique variation among both the wild and domestic populations. • The dominant herbivores of the arid and semi-arid habitats of South America include wild and domestic species. • The genetic and phenotypic integrity of the domestic llama and alpaca are increasingly being threatened by interbreeding. • Loss of vicuña genetic signal in alpaca is due to hybridization and introgression among South American camelids. [ABSTRACT FROM AUTHOR]