Bow shocks, nova shells, disc winds and tilted discs: the nova-like V341 Ara has it all

V341 Ara was recently recognized as one of the closest (d ≃ 150 pc) and brightest (V ≃ 10) nova-like cataclysmic variables. This unique system is surrounded by a bright emission nebula, likely to be the remnant of a recent nova eruption. Embedded within this nebula is a prominent bow shock, where the system’s accretion disc wind runs into its own nova shell. In order to establish its fundamental properties, we present the first comprehensive multiwavelength study of the system. Long-term photometry reveals quasi-periodic, super-orbital variations with a characteristic time-scale of 10–16 d and typical amplitude of ≃1 mag. High-cadence photometry from theTransiting Exoplanet Survey Satellite (TESS) reveals for the first time both the orbital period and a ‘negative superhump’ period. The latter is usually interpreted as the signature of a tilted accretion disc. We propose a recently developed disc instability model as a plausible explanation for the photometric behaviour. In our spectroscopic data, we clearly detect antiphased absorption and emission-line components. Their radial velocities suggest a high mass ratio, which in turn implies an unusually low white-dwarf mass. We also constrain the wind mass-loss rate of the system from the spatially resolved [O III] emission produced in the bow shock; this can be used to test and calibrate accretion disc wind models. We suggest a possible association between V341 Ara and a ‘guest star’ mentioned in Chinese historical records in AD 1240. If this marks the date of the system’s nova eruption, V341 Ara would be the oldest recovered nova of its class and an excellent laboratory for testing nova theory

High rate of in-stent restenosis after coronary intervention in carriers of the mutant mannose-binding lectin allele

BACKGROUND: In-stent restenosis occurs in 10-30% of patients following bare metal stent (BMS) implantation and has various risk factors. Mannose-binding lectin (MBL) is known to have effect on the progression of atherosclerosis. Single nucleotide polymorphisms (SNP) of the MBL2 gene intron 1 (codon 52, 54, 57) are known to modulate the bioavailability of the MBL protein. Our aim was to identify the association of these polymorphisms of the MBL gene in the occurrence of in-stent restenosis after coronary artery bare metal stent implantation. METHODS: In a non-randomized prospective study venous blood samples were collected after recoronarography from 225 patients with prior BMS implantation. Patients were assigned to diffuse restenosis group and control group based on the result of the coronarography. MBL genotypes were determined using quantitative real-time PCR. Proportion of different genotypes was compared and adjusted with traditional risk factors using multivariate logistic regression. RESULTS: Average follow-up time was 1.0 (+ - 1.4) year in the diffuse restenosis group (N = 117) and 2.7 (+ - 2.5) years in the control group (N = 108). The age, gender distribution and risk status was not different between study groups. Proportion of the MBL variant genotype was 26.8% (29 vs. 79 normal homozygous) in the control group and 39.3% (46 vs. 71 normal homozygous) in the restenosis group (p = 0.04). In multivariate analysis the mutant allele was an independent risk factor (OR = 1.96, p = 0.03) of in-stent restenosis. CONCLUSIONS: MBL polymorphisms are associated with higher incidence of development of coronary in-stent restenosis. The attenuated protein function in the mutant allelic genotype may represent the underlying mechanism

Longer and less overlapping food webs in anthropogenically disturbed marine ecosystems: confirmations from the past

The human exploitation of marine resources is characterised by the preferential removal of the largest species. Although this is expected to modify the structure of food webs, we have a relatively poor understanding of the potential consequences of such alteration. Here, we take advantage of a collection of ancient consumer tissues, using stable isotope analysis and SIBER to assess changes in the structure of coastal marine food webs in the South-western Atlantic through the second half of the Holocene as a result of the sequential exploitation of marine resources by hunter-gatherers, western sealers and modern fishermen. Samples were collected from shell middens and museums. Shells of both modern and archaeological intertidal herbivorous molluscs were used to reconstruct changes in the stable isotopic baseline, while modern and archaeological bones of the South American sea lion Otaria flavescens, South American fur seal Arctocephalus australis and Magellanic penguin Spheniscus magellanicus were used to analyse changes in the structure of the community of top predators. We found that ancient food webs were shorter, more redundant and more overlapping than current ones, both in northern-central Patagonia and southern Patagonia. These surprising results may be best explained by the huge impact of western sealing on pinnipeds during the fur trade period, rather than the impact of fishing on fish populations. As a consequence, the populations of pinnipeds at the end of the sealing period were likely well below the ecosystem's carrying capacity, which resulted in a release of intraspecific competition and a shift towards larger and higher trophic level prey. This in turn led to longer and less overlapping food webs

Hunting Landscapes in the North Margin of Lake Viedma (Southern Patagonia, Argentina): Preys, Strategies and Technology

The aim of this paper is to describe and discuss the strategies and technology implemented by Late Holocene hunter-gatherers to hunt their most prominent animal resources, guanaco (Lama guanicoe) and choique (Rhea pennata pennata), in different settings in the north margin of Lake Viedma (Santa Cruz province, Argentina). In order to do that, we use archaeological distributional data from different altitudinal levels, namely lakeshore dunes (255–275 m.a.s.l), mid-altitude plains or pampas (276–900 m.a.s.l.), and Del Tobiano basaltic plateau (≥900 m a.s.l.). The pampas, particularly the grounds below 400 m.a.s.l., may have been used by both species as their wintering grounds (although their permanence in this environment could have occurred throughout the year), while the mid-altitude plains and the plateau seem to have been primarily used by the guanaco as grazing and calving grounds from late spring to early fall, the months in which most of its surface is free of snow. Likely, differences in seasonality, topography and use of these environments by the guanaco and choique social groups may have forced people to adopt different hunting strategies, tactics and weaponry. Frequency variations in the presence of projectile points and bolas at different altitudinal levels have been observed. In the pampas, evidence suggests that guanaco hunting was aided by the use of bow and arrows and/or throwing weapons, such as spears and bolas, the latter likely also used in the hunting of choique. In the plateau, on the other hand, guanaco hunting tactics involved the use of blinds either by individuals or small groups of hunters who were mainly equipped with throwing weapons and/or bow and arrows. The archeological record of the plateau shows a logistic hunting-oriented strategy as well as a residential use during summer months. Artifact density and variety at lakeshore dunes suggest a greater intensity of occupation of these grounds, probably linked to a more residential use—either seasonal (fall/winter) or year-round—made possible by the availability, although in variable density throughout the year, of guanaco and choique. Consequently, the regional archeological landscape exhibits evidence of integration and complementarity of the different altitudinal levels in the northern margin of the Lake Viedma, at least during the Late Holocene.Fil: Belardi, Juan Bautista. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de la Patagonia Austral; ArgentinaFil: Carballo Marina, Flavia Elena. Universidad Nacional de la Patagonia Austral; ArgentinaFil: Barrientos, Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentin