On the mechanical properties and auxetic potential of various organic networked polymers

We simulate and analyse three types of two-dimensional networked polymers which have been predicted to exhibit on-axis auxetic behaviour (negative Poisson's ratio), namely (1) polyphenylacetylene networks that behave like flexing re-entrant honeycombs, commonly referred to as ‘reflexynes’, (2) polyphenylacetylene networks that mimic the behaviour of rotating triangles, commonly referred to as ‘polytriangles’ and (3) networked polymers built from calix[4]arene units. More specifically, we compute and compare their in-plane off-axis mechanical behaviour, in particular their off-axis Poisson's ratios and show that in some cases, the sign and magnitude of the Poisson's ratio are dependent on the direction of loading. We propose two functions that can provide a measure for the extent of auxeticity for such anisotropic materials and show that the polytriangles are predicted as the most auxetic when compared with the other networks with the reflexyne re-entrant networks being the least auxetic.peer-reviewe

Investigating a method to limit damage in Globigerina Limestone, a soft porous stone widely used in historic buildings

A programme of studies is ongoing to investigate the action of environmentally-friendly functionalized polycarboxylates as organic crystallization modifiers on salts on two types of Globigerina Limestone of Malta, to compare their action and behaviour. This was mainly done to verify the potential of such compounds to control, and therefore, limit damage on this locally unexplored territory. The main thrust of the research, at this stage, was to observe modifications to solution transport and salt crystal growth induced in two varieties of the stone by treating under controlled laboratory conditions; work under uncontrolled conditions has also commenced, but will not be discussed here. In this paper, indications of the modifications obtained are discussed, in the context of former trials, the fact that they are still under investigation and with a view on way forward. A discussion establishing a classification for damage limitation is postulated.peer-reviewe

A Search for Technosignatures Around 11,680 Stars with the Green Bank Telescope at 1.15-1.73 GHz

We conducted a search for narrowband radio signals over four observing sessions in 2020-2023 with the L-band receiver (1.15-1.73 GHz) of the 100 m diameter Green Bank Telescope. We pointed the telescope in the directions of 62 TESS Objects of Interest, capturing radio emissions from a total of ~11,680 stars and planetary systems in the ~9 arcminute beam of the telescope. All detections were either automatically rejected or visually inspected and confirmed to be of anthropogenic nature. In this work, we also quantified the end-to-end efficiency of radio SETI pipelines with a signal injection and recovery analysis. The UCLA SETI pipeline recovers 94.0% of the injected signals over the usable frequency range of the receiver and 98.7% of the injections when regions of dense RFI are excluded. In another pipeline that uses incoherent sums of 51 consecutive spectra, the recovery rate is ~15 times smaller at ~6%. The pipeline efficiency affects calculations of transmitter prevalence and SETI search volume. Accordingly, we developed an improved Drake Figure of Merit and a formalism to place upper limits on transmitter prevalence that take the pipeline efficiency and transmitter duty cycle into account. Based on our observations, we can state at the 95% confidence level that fewer than 6.6% of stars within 100 pc host a transmitter that is detectable in our search (EIRP > 1e13 W). For stars within 20,000 ly, the fraction of stars with detectable transmitters (EIRP > 5e16 W) is at most 3e-4. Finally, we showed that the UCLA SETI pipeline natively detects the signals detected with AI techniques by Ma et al. (2023).Comment: 22 pages, 9 figures, submitted to AJ, revise

Two doses of SARS-CoV-2 vaccination induce robust immune responses to emerging SARS-CoV-2 variants of concern

The extent to which immune responses to natural infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and immunization with vaccines protect against variants of concern (VOC) is of increasing importance. Accordingly, here we analyse antibodies and T cells of a recently vaccinated, UK cohort, alongside those recovering from natural infection in early 2020. We show that neutralization of the VOC compared to a reference isolate of the original circulating lineage, B, is reduced: more profoundly against B.1.351 than for B.1.1.7, and in responses to infection or a single dose of vaccine than to a second dose of vaccine. Importantly, high magnitude T cell responses are generated after two vaccine doses, with the majority of the T cell response directed against epitopes that are conserved between the prototype isolate B and the VOC. Vaccination is required to generate high potency immune responses to protect against these and other emergent variants

The genomic landscape of contemporary western Remote Oceanians

International audienceThe Vanuatu archipelago served as a gateway to Remote Oceania during one of the most extensive human migrations to uninhabited lands 3,000 years ago. Ancient DNA studies suggest an initial settlement by East Asian-related peoples that was quickly followed by the arrival of Papuan-related populations, leading to a major population turnover. Yet there is uncertainty over the population processes and the sociocultural factors that have shaped the genomic diversity of ni-Vanuatu, who present nowadays among the world's highest linguistic and cultural diversity. Here, we report new genome-wide data for 1,433 contemporary ni-Vanuatu from 29 different islands, including 287 couples. We find that ni-Vanuatu derive their East Asian-and Papuanrelated ancestry from the same source populations and descend from relatively synchronous, sex-biased admixture events that occurred 1,700-2,300 years ago, indicating a peopling history common to the whole archipelago. However, East Asian-related ancestry proportions differ markedly across islands, suggesting that the Papuan-related population turnover was geographically uneven. Furthermore, we detect Polynesian ancestry arriving 600-1,000 years ago to Central and South Vanuatu in both Polynesian-speaking and non-Polynesian-speaking populations. Last, we provide evidence for a tendency of spouses to carry similar genetic ancestry, when accounting for relatedness avoidance. The signal is not driven by strong genetic effects of specific loci or trait-associated variants, suggesting that it results instead from social assortative mating. Altogether, our findings provide an insight into both the genetic history of ni-Vanuatu populations and how sociocultural processes have shaped the diversity of their genomes

Cartilage status in FAI patients – results from the Danish Hip Arthroscopy Registry (DHAR)

Introduction: The femoroacetabular impingement (FAI) morphology is associated with specific cartilage lesions, which are suspected to be early stages of the osteoarthritic development, which can be the end result of FAI. The cartilage status of FAI afflicted hip joints at the time of arthroscopic management is not fully elucidated. This study from the Danish Hip Arthroscopy Registry (DHAR) will try to show data on the cartilage status from a large cohort. Data from a national registry potentially represent large amounts of population-based epidemiological information from multiple centres and surgeons. Therefore, outcome data might be more reliable for a specific surgical intervention. Methods: This study includes patients operated for symptomatic FAI from January 2012 until December 31st 2013, with a minimum of two-year follow-up and being registered in DHAR. The extent of cartilage damage at the time of surgery is reported and the Patient Related Outcome Measures (PROM) outcome data are presented. Results: Data from a total of 686 FAI procedures in 1082 patients from January 2012 until December 31st 2013 were extracted from DHAR. Cartilage injuries were found in 88% of cases, mainly on the acetabular side. Overall PROM including pain scores improved significantly from preoperative status to follow-up one and two years postoperatively. The Copenhagen Hip and Groin Outcome Score (HAGOS), Hip Sports Activity Scale (HSAS) and global hip function showed less improvements in patients with more severe acetabular cartilage injury. Discussion: The majority of patients with femoroacetabular impingement (FAI) undergoing hip arthroscopy have significant cartilage changes at the time of surgery primarily at the acetabulum and to a lesser degree at the femoral head. During FAI surgery the majority of patients have cartilage debridement performed but rarely cartilage repair. The presence of severe cartilage injury at the time of arthroscopic FAI surgery results in reduced subjective outcome and hip function

Stable isotopes reveal linkages between ocean climate, plankton community dynamics, and survival of two populations of Atlantic salmon (Salmo salar)

An 18-year record of stable isotopes from Atlantic salmon (Salmo salar) migrating to two different regions of the North Atlantic reveals climate-driven subdecadal variations. Time-series of carbon isotopes in one salmon stock, thought to feed in the Faroes/Iceland Basin area, show Subpolar Gyre (SPG) modal variability, which is not seen in fish feeding in the Norwegian Sea. At times of weak SPG circulation, when waters in the Iceland Basin are relatively warm, carbon isotope values are somewhat negative, suggesting possible changes in phytoplankton community structure. The fluctuations in plankton community dynamics suggested by the stable isotope values are coincident with fluctuations in the estimates of marine mortality in one sea-winter fish feeding in the Norwegian Sea, but not in those feeding in the Iceland Basin. Marine mortality in salmon feeding in the Iceland Basin is therefore likely to be more strongly influenced by factors other than bottom–up control. Time-series analysis of stable isotopes in consumer tissues provides information on the interaction between climate and ecosystem dynamics on the scale of individual stocks and cohorts

Genomic insights into population history and biological adaptation in Oceania

The Pacific region is of major importance for addressing questions regarding human dispersals, interactions with archaic hominins and natural selection processes1. However, the demographic and adaptive history of Oceanian populations remains largely uncharacterized. Here we report high-coverage genomes of 317 individuals from 20 populations from the Pacific region. We find that the ancestors of Papuan-related (‘Near Oceanian’) groups underwent a strong bottleneck before the settlement of the region, and separated around 20,000–40,000 years ago. We infer that the East Asian ancestors of Pacific populations may have diverged from Taiwanese Indigenous peoples before the Neolithic expansion, which is thought to have started from Taiwan around 5,000 years ago2–4. Additionally, this dispersal was not followed by an immediate, single admixture event with Near Oceanian populations, but involved recurrent episodes of genetic interactions. Our analyses reveal marked differences in the proportion and nature of Denisovan heritage among Pacific groups, suggesting that independent interbreeding with highly structured archaic populations occurred. Furthermore, whereas introgression of Neanderthal genetic information facilitated the adaptation of modern humans related to multiple phenotypes (for example, metabolism, pigmentation and neuronal development), Denisovan introgression was primarily beneficial for immune-related functions. Finally, we report evidence of selective sweeps and polygenic adaptation associated with pathogen exposure and lipid metabolism in the Pacific region, increasing our understanding of the mechanisms of biological adaptation to island environments