Chemistry and meteorology, 1700–1825

In 1639–1640 Benedetto Castelli (1577–1643) wrote a treatise on the loadstone which is quite unlike any of its contemporaries. In it are the origins of the notion of elementary magnets sharing a common alignment, the idea that all materials are magnetic in different ways, and the first intimation of the conception of magnetic domains. Castelli did not publish his treatise. Nevertheless his work was noted during his life-time, and may have exerted an influence on the development of magnetic theory in the 17th century. The treatise was published in 1883. Since then, however, it has either been neglected or not appreciated. It deserves being rescued from the neglect of more than three centuries.     

Jean Méry (1645–1722) and his ideas on the foetal blood flow

We present an analysis, and first full English translation, of a paper by Kant entitled ‘Über die Vulcane im Monde’ (1785). Kant became interested in the question of whether the mountains of the Moon were extinct volcanoes. Stimulated by the work of Herschel, Aepinus, and others, he considered the appearance of the Moon's surface and the possibility of lunar vulcanism. From this, he was led to consider the structures of mountain ranges on the Earth, which he decided were non-volcanic in origin, being produced by eruptions of vapours from the interior of the Earth soon after it formed from an original ‘chaos’. Kant developed his ideas in such a way as to yield a characteristic eighteenth-century ‘theory of the Earth’. We argue that the empirical base of his theory was provided by knowledge of the mountain ranges of Bohemia and Moravia. Analogies based on observations of the Moon further assisted in the construction of the theory. But the reasoning ran in two directions: what was seen on the Moon was construed in terms of what Kant knew of the Earth's topography; and the Earth's topography was presumed to be analogous to that of the Moon, for both the Earth and the Moon (and indeed all heavenly bodies) supposedly had essentially similar origins. Kant's ideas of 1785 are related to his earlier writings of 1754, 1755, and 1756, and also to the lectures on physical geography that he presented at Königsberg.     

A bibliographical study of the introduction of Lavoisier's Traité élémentaire de chimie into Great Britain and America

As the most famous woman scientist of the twentieth century, there has been no shortage of books and articles on the life and career of Marie Curie (1867–1934). Her role as a director of a laboratory-based research school in the new scientific field of radioactivity, a field which embraced both chemistry and physics, however, has never been examined. In recent years, there has been a growing interest in the question of research schools, and Morrell, Ravetz, Geison, and Klosterman, amongst others, have written on this subject. Using, in part, the methodology of Morrell, this paper investigates the role of Marie Curie as a school director in the Paris Faculty in the years 1907–14, examining the work and characteristics of her school and assessing her effectiveness as a director.     

基于MDA机制的跨洋航空网时隙分配方法

考虑到飞机跨洋飞行的限制性条件,提出了一种改进的多单元双向拍卖机制来满足跨洋航空主干网的时隙分配的需要。该机制将VCG双向拍卖和传统的多单元双向拍卖进行结合和改进,并从激励相容、预算平衡、个人理性和机制效率等方面证明了该双向拍卖机制的性质。最后的仿真结果表明,该双向拍卖机制具有较高的效率。     

一种基于重复博弈的频谱分配策略

针对动态频谱接入,提出了一种基于重复博弈的频谱共享分配策略。通过基于惩罚的防欺骗策略,参与用户将约束自己的行为以合作方式共享频谱、实现频谱分配,保证合作竞争的诚实性。仿真结果显示,该合作规则方法能够很好地降低用户间的干扰,防欺骗方式也能很好地约束参与人保持合作。     

The unconventional secretion of stress-inducible protein 1 by a heterogeneous population of extracellular vesicles

The co-chaperone stress-inducible protein 1 (STI1) is released by astrocytes, and has important neurotrophic properties upon binding to prion protein (PrP^C). However, STI1 lacks a signal peptide and pharmacological approaches pointed that it does not follow a classical secretion mechanism. Ultracentrifugation, size exclusion chromatography, electron microscopy, vesicle labeling, and particle tracking analysis were used to identify three major types of extracellular vesicles (EVs) released from astrocytes with sizes ranging from 20–50, 100–200, and 300–400 nm. These EVs carry STI1 and present many exosomal markers, even though only a subpopulation had the typical exosomal morphology. The only protein, from those evaluated here, present exclusively in vesicles that have exosomal morphology was PrP^C. STI1 partially co-localized with Rab5 and Rab7 in endosomal compartments, and a dominant-negative for vacuolar protein sorting 4A (VPS4A), required for formation of multivesicular bodies (MVBs), impaired EV and STI1 release. Flow cytometry and PK digestion demonstrated that STI1 localized to the outer leaflet of EVs, and its association with EVs greatly increased STI1 activity upon PrP^C-dependent neuronal signaling. These results indicate that astrocytes secrete a diverse population of EVs derived from MVBs that contain STI1 and suggest that the interaction between EVs and neuronal surface components enhances STI1–PrP^C signaling.     

The insecticidal potential of venom peptides

Pest insect species are a burden to humans as they destroy crops and serve as vectors for a wide range of diseases including malaria and dengue. Chemical insecticides are currently the dominant approach for combating these pests. However, the de-registration of key classes of chemical insecticides due to their perceived ecological and human health risks in combination with the development of insecticide resistance in many pest insect populations has created an urgent need for improved methods of insect pest control. The venoms of arthropod predators such as spiders and scorpions are a promising source of novel insecticidal peptides that often have different modes of action to extant chemical insecticides. These peptides have been optimized via a prey–predator arms race spanning hundreds of millions of years to target specific types of insect ion channels and receptors. Here we review the current literature on insecticidal venom peptides, with a particular focus on their structural and pharmacological diversity, and discuss their potential for deployment as insecticides.     

Overactive bone morphogenetic protein signaling in heterotopic ossification and Duchenne muscular dystrophy

Bone morphogenetic proteins (BMPs) are important extracellular cytokines that play critical roles in embryogenesis and tissue homeostasis. BMPs signal via transmembrane type I and type II serine/threonine kinase receptors and intracellular Smad effector proteins. BMP signaling is precisely regulated and perturbation of BMP signaling is connected to multiple diseases, including musculoskeletal diseases. In this review, we will summarize the recent progress in elucidation of BMP signal transduction, how overactive BMP signaling is involved in the pathogenesis of heterotopic ossification and Duchenne muscular dystrophy, and discuss possible therapeutic strategies for treatment of these diseases.     

Diet composition of an invasive population of Lithobates catesbeianus (American Bullfrog) from Argentina

The American bullfrog Lithobates catesbeianus has been introduced around the world, with invasive populations reported from almost all South American countries. A population of this species was introduced in the Calingasta department of San Juan province, which is an arid environment in western Argentina. This work provides information on the dietary composition of an invasive population of L. catesbeianus, and compares the degree of dietary overlap between adults and juveniles. Stomach contents of 169 bullfrogs (82 adults and 87 juveniles) were analysed. Adults consumed 40 prey taxa and Hymenoptera (Insecta) was the most numerous prey item (41.8%), followed by Araneae (13.6%) and Aeglidae (13.4%). Juveniles consumed 29 prey taxa and Hymenoptera constituted the highest percentage in prey number (77.2%). The trophic overlap niche index at the same level shows a value of 0.64 overlap in dietary community between adults and juveniles of this bullfrog. Aeglidae was volumetrically the most important trophic item (25.4%), followed by Anura (25.02%). Our results showed that cannibalism in bullfrogs is more common than the consumption of native anurans, coinciding with that reported in other populations of introduced bullfrogs. The high similarity in the diets of both size classes and the association between the size of the predator and prey suggest that the impact caused by bullfrogs throughout their ontogeny is high and probably has an impact on their prey. Freshwater crabs are the main items in the diet of Lithobates catesbeianus in other introduced populations and are usually the most conspicuous at our study site. The crabs in freshwater ecosystems are part of the lowest trophic level in the food chain. The major threats to the southern region’s freshwater crabs include deforestation, farming and exotic species. Lithobates catesbeianus has a generalist diet and high overlap between adults and juveniles.