Animal-sediment interactions: the effect of ingestion and excretion by worms on mineralogy

International audienceBy controlled experiments that simulate marine depositional environments, it is shown that accelerated weathering and clay mineral authigenesis occur during the combined process of ingestion, digestion and excretion of fine-grained sediment by two species of annelid worms. Previously characterized synthetic mud was created using finely ground, low-grade metamorphic slate (temperature approximately 300°C) containing highly crystalline chlorite and muscovite. This was added to experiment and control tanks along with clean, wind-blown sand. Faecal casts were collected at regular intervals from the experimental tanks and, less frequently, from the control tanks. Over a period of many months the synthetic mud (slate) proved to be unchanged in the control tanks, but was significantly different in faecal casts from the experimental tanks that contained the worms Arenicola marina and Lumbricus terrestris. Chlorite was preferentially destroyed during digestion in the gut of A. marina. Both chlorite and muscovite underwent XRD peak broadening with a skew developing towards higher lattice spacing, characteristic of smectite formation. A neoformed Fe-Mg-rich clay mineral (possibly berthierine) and as-yet undefined clay minerals with very high d-spacing were detected in both A. marina and L. terrestris cast samples. We postulate that a combination of the low pH and bacteria-rich microenvironment in the guts of annelid worms may radically accelerate mineral dissolution and clay mineral precipitation processes during digestion. These results show that macrobiotic activity significantly accelerates weathering and mineral degradation as well as mineral authigenesis. The combined processes of sediment ingestion and digestion thus lead to early diagenetic growth of clay minerals in clastic sediments

Torsion-induced persistent current in a twisted quantum ring

We describe the effects of geometric torsion on the coherent motion of electrons along a thin twisted quantum ring. The geometric torsion inherent in the quantum ring triggers a quantum phase shift in the electrons' eigenstates, thereby resulting in a torsion-induced persistent current that flows along the twisted quantum ring. The physical conditions required for detecting the current flow are discussed.Comment: 9 pages, 3 figure

Reevaluación crítica del holotipo de Beothukis mistakensis, único organismo rangeomorfo excepcionalmente preservado en Mistaken Point, Terranova, Canadá

The holotype of Beothukis mistakensis in Mistaken Point, Newfoundland, is the only currently known specimen that can be definitely placed within the species. Morphological differences between the holotype of B. mistakensis and the well-constrained species plumosa suggest that the two are not congeneric and Culmofrons plumosa should be retained as a valid taxon as originally established.El holotipo de Beothukis mistakensis en Mistaken Point, Terranova, es el único ejemplar actualmente conocido que puede ser colocado definitivamente dentro de la especie. Las diferencias morfológicas entre el holotipo de B. mistakensis y la especie plumosa sugieren que ambas no son congéneres y que Culmofrons plumosa debería conservarse como un taxón válido tal como se estableció originalmente

Even faster sorting of (not only) integers

In this paper we introduce RADULS2, the fastest parallel sorter based on radix algorithm. It is optimized to process huge amounts of data making use of modern multicore CPUs. The main novelties include: extremely optimized algorithm for handling tiny arrays (up to about a hundred of records) that could appear even billions times as subproblems to handle and improved processing of larger subarrays with better use of non-temporal memory stores

Secondary Level Achievement Non-Intellective Factors Implicated in the Process and Product of Performance

The study was developed in the context of Personality and Social Cognitive Theory with constructs that encapsulate non-intellective processes of academic achievement. The goal was to explore the role of the Five Factor Model (FFM) of personality in academic performance and to use this model as a reference point to test the incremental validity of two measures of Self-efficacy (Academic and Emotional) and an indicator of Absenteeism. Participants (N = 120) were comprised of 17-year-old male (n = 47) and female (n = 73) opportunistically sampled secondary level college students. A cross-sectional design was used to examine the relationship between the independent variables (FFM, Academic Self-efficacy, Emotional Self-efficacy, and Absenteeism) and the outcome variable, Grade Points Average (GPA). Correlation analysis found that four FFM factors and the two Self-efficacy measures were associated with GPA. In a hierarchical regression analysis, the FFM explained 22% variance on performance and the two Self-efficacy measures added 9% incremental variance followed by 3% for Absenteeism. Overall, the non-intellective constructs explain a substantial 34% variance on achievement and provide focal points for theoretical, empirical, and pedagogical evaluation. Moreover, they are suggestive of the pathways and processes that support learning, augment ability, and enhance achievement

Confirming the metazoan character of a 565Ma trace-fossil assemblage from Mistaken Point, Newfoundland

Surface locomotory trace fossils from the Mistaken Point Formation of Newfoundland, dated at ∼ 565 Ma, suggest that organisms capable of controlled locomotion and possessing muscular tissue may have existed among Avalonian Ediacaran macrofossil assemblages. Here we describe the Mistaken Point trace-fossil assemblage in full, discuss its stratigraphic context within the Mistaken Point Formation, and explore the competing hypotheses for the formation of the traces. We find that the trace fossils, preserved within a turbidite succession in a deep-marine depositional environment, are not attributable to abiogenic structures, to Ediacaran tubular or filamentous body fossils, to rangeomorph stems, or to a host of late Ediacaran and early Phanerozoic ichnofossils. Specimens within the assemblage show some similarities to the ichnogenera Helminthoidichnites and Archaeonassa, but discrepancies in certain aspects of their structure mean that we do not formally attribute them to these ichnotaxa at this time. The Mistaken Point ichnofossils possess morphological characteristics indicative of formation by an organism with a round base. Comparison with traces formed by modern organisms of such character appears to rule out formation by protistan, echinoderm, or annelid styles of movement, but is consistent with organisms moving via muscular controlled locomotion in a similar way to some modern mollusks and actinian cnidarians. We suggest therefore that the Mistaken Point trace-fossil assemblage reveals the presence of muscular metazoans in late Ediacaran deep-marine ecosystems. Such organisms cannot yet be attributed to specific phyla, but their inferred locomotory mechanisms share closest similarities with those utilized by extant actinians

High-efficiency, high-power difference-frequency generation of 0.9–1.5 μm light in BBO

An efficient method for generation of high energy pulsed ir light between 0.9 and 1.5 μm is described. The technique uses difference frequency mixing of pulsed, visible dye and Nd:YAG laser light in a 10 mm long BBO crystal. Quantum efficiencies of up to 23% and ir pulse energies up to 4.5 mJ are demonstrated. The low shot-to-shot fluctuations of difference frequency generation in BBO make this technique an attractive alternative to the conventional optical parametric oscillator or Raman shifting methods that are currently used to access this spectral region

The Unique Impact of COVID-19 on Human Gut Microbiome Research

The coronavirus (COVID-19) pandemic has disrupted clinical trials globally, with unique implications for research into the human gut microbiome. In this mini-review, we explore the direct and indirect influences of the pandemic on the gut microbiome and how these can affect research and clinical trials. We explore the direct bidirectional relationships between the COVID-19 virus and the gut and lung microbiomes. We then consider the significant indirect effects of the pandemic, such as repeated lockdowns, increased hand hygiene, and changes to mood and diet, that could all lead to longstanding changes to the gut microbiome at an individual and a population level. Together, these changes may affect long term microbiome research, both in observational as well as in population studies, requiring urgent attention. Finally, we explore the unique implications for clinical trials using faecal microbiota transplants (FMT), which are increasingly investigated as potential treatments for a range of diseases. The pandemic introduces new barriers to participation in trials, while the direct and indirect effects laid out above can present a confounding factor. This affects recruitment and sample size, as well as study design and statistical analyses. Therefore, the potential impact of the pandemic on gut microbiome research is significant and needs to be specifically addressed by the research community and funders