Nanoscale assembly processes revealed in the nacroprismatic transition zone of Pinna nobilis mollusc shells

Intricate biomineralization processes in molluscs engineer hierarchical structures with meso-, nano-, and atomic architectures that give the final composite material exceptional mechanical strength and optical iridescence on the macroscale. This multiscale biological assembly inspires new synthetic routes to complex materials. Our investigation of the prism-nacre interface reveals nanoscale details governing the onset of nacre formation using high-resolution scanning transmission electron microscopy. A wedge polishing technique provides unprecedented, large-area specimens required to span the entire interface. Within this region, we find a transition from nanofibrillar aggregation to irregular early-nacre layers, to well-ordered mature nacre suggesting the assembly process is driven by aggregation of nanoparticles (~50-80 nm) within an organic matrix that arrange in fiber-like polycrystalline configurations. The particle number increases successively and, when critical packing is reached, they merge into early-nacre platelets. These results give new insights into nacre formation and particle-accretion mechanisms that may be common to many calcareous biominerals.Comment: 5 Figure

Transposable elements and the dynamic somatic genome

Although alterations in the genomes of somatic cells cannot be passed on to future generations, they can have beneficial or detrimental effects on the host organism, depending on the context in which they occur. This review outlines the ways in which transposable elements have important consequences for somatic cell genomes

Cerebral Microbleeds in a Stroke Prevention Clinic.

The objective of this study is to assess the effectiveness of a stroke clinic in stroke prevention and progression of cerebral microbleeds (CMB). We conducted a retrospective observational study of patients who visited a stroke clinic between January 2011 and March 2017. Susceptibility-weighted imaging (SWI) MRI studies were obtained at baseline and follow-up visits to identify new infarctions and CMB progression. Patients with CMB who also underwent brain computed tomography (CT) imaging were identified and their cerebral arterial calcification was quantified to evaluate the relationship between the extent of intracranial calcification and CMB burden. A total of 64 stroke patients (mean age 73.1 ± 11.0, 47% males) had CMB on baseline and follow-up MRI studies. During a mean follow-up period of 22.6 months, four strokes occurred (4/64, 6%; 3 ischemic, 1 hemorrhagic), producing mild neurological deficit. Progression of CMB was observed in 54% of patients with two MRIs and was significantly associated with length of follow-up. Subjects with intracranial calcification score > 300 cm3 had higher CMB count than those with scores <300 cm3 at both baseline (12.6 ± 11.7 vs. 4.9 ± 2.2, p = 0.02) and follow-up (14.1 ± 11.8 vs. 5.6 ± 2.4, p = 0.03) MRI evaluations. Patients with CMB had a relatively benign overall clinical course. The association between CMB burden and intracranial calcification warrants further study

Analytical Modelling of the Spread of Disease in Confined and Crowded Spaces

Since 1927, until recently, models describing the spread of disease have mostly been of the SIR-compartmental type, based on the assumption that populations are homogeneous and well-mixed. The focus of these models have typically been on large-scale analysis of scenarios such as cities, nations or even world scale. SIR models are appealing because of their simplicity, but their parameters, especially the transmission rate, are complex and depend on a number of factors, which makes it hard to predict how a change of a single environmental, demographic, or epidemiological factor will affect the population. Therefore, in this contribution we start to unpick the transmission-rate parameter. Analysing the implications that arise when taking crowd behaviour explicitly into account, we show how both the rate of infection as well as the walking speed depend on the local crowd density around an infected individual. The combined effect is that the rate of infection at a population scale has an analytically tractable non-linear dependency on crowd density. We model the spread of a hypothetical disease in a corridor and compare our new model with a typical compartmental model, which highlights the regime in which current models may not produce credible results

Tundra landform and vegetation productivity trend maps for the Arctic Coastal Plain of northern Alaska

Arctic tundra landscapes are composed of a complex mosaic of patterned ground features, varying in soil moisture, vegetation composition, and surface hydrology over small spatial scales (10–100 m). The importance of microtopography and associated geomorphic landforms in influencing ecosystem structure and function is well founded, however, spatial data products describing local to regional scale distribution of patterned ground or polygonal tundra geomorphology are largely unavailable. Thus, our understanding of local impacts on regional scale processes (e.g., carbon dynamics) may be limited. We produced two key spatiotemporal datasets spanning the Arctic Coastal Plain of northern Alaska (~60,000 km2) to evaluate climate-geomorphological controls on arctic tundra productivity change, using (1) a novel 30m classification of polygonal tundra geomorphology and (2) decadal-trends in surface greenness using the Landsat archive (1999–2014). These datasets can be easily integrated and adapted in an array of local to regional applications such as (1) upscaling plot-level measurements (e.g., carbon/energy fluxes), (2) mapping of soils, vegetation, or permafrost, and/or (3) initializing ecosystem biogeochemistry, hydrology, and/or habitat modeling

Who discovered the binary system and arithmetic? Did Leibniz plagiarize Caramuel?

Gottfried Wilhelm Leibniz (1646–1716) is the self-proclaimed inventor of the binary system and is considered as such by most historians of mathematics and/or mathematicians. Really though, we owe the groundwork of today’s computing not to Leibniz but to the Englishman Thomas Harriot and the Spaniard Juan Caramuel de Lobkowitz (1606–1682), whom Leibniz plagiarized. This plagiarism has been identified on the basis of several facts: Caramuel’s work on the binary system is earlier than Leibniz’s, Leibniz was acquainted—both directly and indirectly—with Caramuel’s work and Leibniz had a natural tendency to plagiarize scientific works.2017-1

Firearm-Related Pediatric Head Trauma: A Scoping Review.

BACKGROUND: Firearm-related injury is a significant cause of morbidity and mortality in pediatric populations. Despite a disproportionate role in the most morbid outcomes in both traumatic brain injury and firearm-related injury populations, firearm-related traumatic brain injury (frTBI) is an understudied epidemiological entity. There is need to increase understanding and promote interventions that reduce this burden of disease. OBJECTIVE: To assess the evidence characterizing pediatric frTBI to highlight trends and gaps regarding burden of disease and interventions to reduce frTBI. METHODS: We conducted a scoping review under Preferred Reporting Items for Systematic Reviews and Meta-Analyses-Scoping Review (PRISMA-ScR) guidelines on peer-reviewed studies across 5 databases (Medline OVID, EMBASE, Web of Science Legal Collection, PsychINFO, and Academic Search Complete). English studies examining pediatric frTBI epidemiology, prevention, and/or social or legal policy advocacy were included. Articles were excluded if they more generally discussed pediatric firearm-related injury without specific analysis of frTBI. RESULTS: Six studies satisfied inclusion criteria after screening and full-text assessment. Limited studies specifically addressed the burden of disease caused by frTBI. There was an increased risk for both injury and death from frTBI in men, preteenage and teenage youths, minorities, and individuals in firearm-owning households. Further study is required to ascertain if suggested methods of targeted patient screening, firearm-injury prevention counseling, and advocacy of safety-oriented policy tangibly affect rates or outcomes of pediatric frTBI. CONCLUSION: By understanding published epidemiological data and areas of intervention shown to reduce frTBIs, neurosurgeons can become further engaged in public health and prevention rather than strictly treatment after injury