Cardiovascular effects of calcium supplementation

Peer reviewedPostprin

Exploration of the solar system

A sourcebook of information on the solar system and the technology used for its exploration is presented. An outline of the potential achievements of solar system exploration is given along with a course of action which maximizes the rewards to mankind

Effect of calcium supplements on risk of myocardial infarction and cardiovascular events : meta-analysis

Peer reviewedPublisher PD

Invasive crayfish impacts on native fish diet and growth vary with fish life stage

Assessing the impacts of invasive organisms is a major challenge in ecology. Some widespread invasive species such as crayfish are potential competitors and reciprocal predators of ecologically and recreationally important native fish species. Here, we examine the effects of signal crayfish (Pacifastacus leniusculus) on the growth, diet, and trophic position of the chub (Squalius cephalus) in four rivers in Britain. Growth rates of 0+ chub were typically lower in sympatric populations with signal crayfish compared with allopatric populations, and this effect could be traced through to 2+ chub in one river. However, growth rates of older chub (5+ to 6+) were typically higher in the presence of crayfish. Sympatry with crayfish resulted in lower chub length-at-age and mass-at-age in half of the rivers sampled, with no change detected in the other rivers. Stable isotope analyses (δ13C and δ15N) revealed that both chub and crayfish were omnivorous, feeding at multiple trophic levels and occupying similar trophic positions. We found some evidence that chub trophic position was greater at invaded sites on one river, with no difference detected on a second river. Mixing models suggested crayfish were important food items for both small and large chub at invaded sites. This study provides evidence that invasive species can have both positive and negative effects on different life stages of a native species, with the net impact likely to depend on responses at the population level

Identifying the causal mechanisms of the quiet eye

Scientists who have examined the gaze strategies employed by athletes have determined that longer quiet eye (QE) durations (QED) are characteristic of skilled compared to less-skilled performers. However, the cognitive mechanisms of the QE and, specifically, how the QED affects performance are not yet fully understood. We review research that has examined the functional mechanism underlying QE and discuss the neural networks that may be involved. We also highlight the limitations surrounding QE measurement and its definition and propose future research directions to address these shortcomings. Investigations into the behavioural and neural mechanisms of QE will aid the understanding of the perceptual and cognitive processes underlying expert performance and the factors that change as expertise develops

Reversible Capacity of Conductive Carbon Additives at Low Potentials: Caveats for Testing Alternative Anode Materials for Li-Ion Batteries

The electrochemical performance of alternative anode materials for Li-ion batteries is often measured using composite electrodes consisting of active material and conductive carbon additives. Cycling of these composite electrodes at low voltages demonstrates charge storage at the operating potentials of viable anodes, however, the conductive carbon additive is also able to store charge in the low potential regime. The contribution of the conductive carbon additives to the observed capacity is often neglected when interpreting the electrochemical performance of electrodes. To provide a reference for the contribution of the carbons to the observed capacity, we report the charge storage behavior of two common conductive carbon additives Super P and Ketjenblack as a function of voltage, rate, and electrolyte composition. Both carbons exhibit substantial capacities after 100 cycles, up to 150 mAh g^(−1), when cycled to 10 mV. The capacity is dependent on the discharge cutoff voltage and cycling rate with some dependence on electrolyte composition. The first few cycles are dominated by the formation of the SEI followed by a fade to a steady, reversible capacity thereafter. Neglecting the capacity of the carbon additive can lead to significant errors in the estimation of charge storage capabilities of the active material

Modeling the human bone marrow niche in mice: From host bone marrow engraftment to bioengineering approaches

Xenotransplantation of patient-derived samples in mouse models has been instrumental in depicting the role of hematopoietic stem and progenitor cells in the establishment as well as progression of hematological malignancies. The foundations for this field of research have been based on the development of immunodeficient mouse models, which provide normal and malignant human hematopoietic cells with a supportive microenvironment. Immunosuppressed and genetically modified mice expressing human growth factors were key milestones in patient-derived xenograft (PDX) models, highlighting the importance of developing humanized microenvironments. The latest major improvement has been the use of human bone marrow (BM) niche-forming cells to generate human-mouse chimeric BM tissues in PDXs, which can shed light on the interactions between human stroma and hematopoietic cells. Here, we summarize the methods used for human hematopoietic cell xenotransplantation and their milestones and review the latest approaches in generating humanized BM tissues in mice to study human normal and malignant hematopoiesis

Octahedral Tilt Instability of ReO_3-type Crystals

The octahedron tilt transitions of ABX_3 perovskite-structure materials lead to an anti-polar (or antiferroelectric) arrangement of dipoles, with the low temperature structure having six sublattices polarized along various crystallographic directions. It is shown that an important mechanism driving the transition is long range dipole-dipole forces acting on both displacive and induced parts of the anion dipole. This acts in concert with short range repulsion, allowing a gain of electrostatic (Madelung) energy, both dipole-dipole and charge-charge, because the unit cell shrinks when the hard ionic spheres of the rigid octahedron tilt out of linear alignment.Comment: 4 page with 3 figures included; new version updates references and clarifies the argument