Science & Mathematics

We introduce a new jet substructure technique called Recursive Soft Drop, which generalizes the Soft Drop algorithm to have multiple grooming layers. Like the original Soft Drop method, this new recursive variant traverses a jet clustering tree to remove soft wide-angle contamination. By enforcing the Soft Drop condition N times, Recursive Soft Drop improves the jet mass resolution for boosted hadronic objects like W bosons, top quarks, and Higgs bosons. We further show that this improvement in mass resolution persists when including the effects of pileup, up to large pileup multiplicities. In the limit that N goes to infinity, the resulting groomed jets formally have zero catchment area. As an alternative approach, we present a bottom-up version of Recursive Soft Drop which, in its local form, is similar to Recursive Soft Drop and which, in its global form, can be used to perform event-wide grooming.

In the first part of the paper the relative stabilities of the different martensitic phases, mainly in Cu-Zn-Al, are compared. It is shown that the differences in enthalpy of formation between the fcc type 3R or 6R and the 9R, 18R or 2H structures are above all due to a lattice distortion which reduces the energy per stacking fault, considering 9R, 18R and 2H as a basic face centered lattice into which faults are introduced on each third or second plane. In the second part the factors are discussed which are important in the relative stabilities not only between the matrix and martensite phases, but also for the equilibrium phases in the noble metal alloys. These are : i) the vibrational entropy difference ΔS, which is a function mainly of electron concentration e/a. It depends little, if at all, on the special alloy system, on the degree of long range order, or on temperature ; ii) the stability of the average periodic lattice which is a smooth function of e/a, without any indication of nesting effects at intermediate e/a ; iii) the pair interchange energies which depend strongly on the alloy system. They are a function of the pair distance but otherwise are structure independent. They determine most of the enthalpy of formation and simultaneously account for the long range order contribution.

This article focuses on the presence of the Other in rituals among the Kulung, a small tibeto-burmese group living in the Nepalese Himalayas. These figures of the Other are those of errant and predatory spirits, emanations of the dangerous otherness of other groups. The presentation of these spirits reveal the existence of two sets: spirits from dead belonging to other Kirant groups, whose ritual is done in "ritual language", and spirits from Indo-Nepalese deaths, whose rituals are performed in Nepali. We show how the mode of pacification of these spirits betrays the relationship that the Kulung maintain with the groups of which these spirits are said to emanate. In conclusion, attention is paid to the importance of diviners, another form of presence of others in the ritual, since they can belong to any group, in the emergence of a form of regional religiosity.

This note investigates the trade-off arising in disturbance attenuation for nonlinear feedback systems in the framework of integral input-to-state stability. Similarly to the linear case, we show that if a gain tuning on one subsystem is used to drastically reduce the effect of its exogenous disturbances, then the other subsystem's disturbance attenuation is qualitatively the same as in open loop.

A workshop has explored interactions of materials science, applied mechanics, physics and mathematics in understanding fundamentals of martensitic transformations. System theory offers a framework for addressing realistic complexity. Theory of invariant-plane kinematics has been extended to multivariant plate groups and hierarchical structures. Electronic total energy calculations explore the origins of martensitic phase stability, and Landau-Ginzberg models for transformations with and without shuffles provide nonlocal continuum theories for treatment of interfacial structure and mobility as well as the competition between classical and nonclassical transformation mechanisms. Quantitative kinetic theory incorporates defect distributions, but requires further analysis of the evolution of mean particle volume. Kinetic theory provides the basis for constitutive relations for transformation plasticity.

he history of the genus Pan is a topic of enduring interest. Chim- panzees (Pan troglodytes) are often divided into subspecies, but the population structure and genetic history of chimpanzees across Africa remain unclear. Some population genetics studies have led to speculation that, until recently, this species constituted a single population with ongoing gene flow across its range, which resulted in a continuous gradient of allele frequencies. Chimpanzees, desig- nated here as P. t. ellioti, occupy the Gulf of Guinea region that spans southern Nigeria and western Cameroon at the center of the distribution of this species. Remarkably, few studies have in- cluded individuals from this region, hindering the examination of chimpanzee population structure across Africa. Here, we analyzed microsatellite genotypes of 94 chimpanzees, including 32 desig- nated as P. t. ellioti. We find that chimpanzees fall into three major populations: (i) Upper Guinea in western Africa (P. t. verus); (ii) the Gulf of Guinea region (P. t. ellioti); and (iii) equatorial Africa (P. t. troglodytes and P. t. schweinfurthii). Importantly, the Gulf of Guinea population is significantly different genetically from the others, sharing a last common ancestor with the populations in Upper Guinea ∼0.46 million years ago (mya) and equatorial Africa ∼0.32 mya. Equatorial chimpanzees are subdivided into up to three populations occupying southern Cameroon, central Africa, and eastern Africa, which may have constituted a single population until ∼0.10–0.11 mya. Finally, occasional hybridization may be occurring between the Gulf of Guinea and southern Cameroon populations.

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Nature-derived or biologically encouraged hydrogels have attracted considerable interest in numerous biomedical applications owing to their multidimensional utility and effectiveness. The internal architecture of a hydrogel network, the chemistry of the raw materials involved, interaction across the interface of counter ions, and the ability to mimic the extracellular matrix (ECM) govern the clinical efficacy of the designed hydrogels. This review focuses on the mechanistic viewpoint of different biologically driven/inspired biomacromolecules that encourages the architectural development of hydrogel networks. In addition, the advantage of hydrogels by mimicking the ECM and the significance of the raw material selection as an indicator of bioinertness is deeply elaborated in the review. Furthermore, the article reviews and describes the application of polysaccharides, proteins, and synthetic polymer-based multimodal hydrogels inspired by or derived from nature in different biomedical areas. The review discusses the challenges and opportunities in biomaterials along with future prospects in terms of their applications in biodevices or functional components for human health issues. This review provides information on the strategy and inspiration from nature that can be used to develop a link between multimodal hydrogels as the main frame and its utility in biomedical applications as the primary target.

Piwi-interacting RNAs (piRNAs) are known to regulate transposon activity in germ cells of several animal models that propagate sexually. However, the role of piRNAs during asexual reproduction remains almost unknown. Aphids that can alternate sexual and asexual reproduction cycles in response to seasonal changes of photoperiod provide a unique opportunity to study piRNAs and the piRNA pathway in both reproductive modes. Taking advantage of the recently sequenced genome of the pea aphid Acyrthosiphon pisum, we found an unusually large lineage-specific expansion of genes encoding the Piwi sub-clade of Argonaute proteins. In situ hybridisation showed differential expressions between the duplicated piwi copies: while Api-piwi2 and Api-piwi6 are "specialised" in germ cells their most closely related copy, respectively Api-piwi5 and Api-piwi3, are expressed in the somatic cells. The differential expression was also identified in duplicated ago3: Api-ago3a in germ cells and Api-ago3b in somatic cells. Moreover, analyses of expression profiles of the expanded piwi and ago3 genes by semi-quantitative RT-PCR showed that expressions varied according to the reproductive types. These specific expression patterns suggest that expanded aphid piwi and ago3 genes have distinct roles in asexual and sexual reproduction.

The potential large applications of ceramic composites require the preservation of their thermomechanical properties for long duration, in oxidative environments, under high temperature fatigue conditions and/or thermal cycling. This implies that the fibers and matrix properties, cracks deviation and load transfer at the fiber-matrix interface must be maintained. Different possibilities to progress in that way, that is to reduce the oxidation penetration in the parts or to improve the oxidation resistance at the fiber-matrix interface are examined. They include the use of protective external coatings, the development of new matrices or more oxidation resistant interphases. All components of the composite are examined successively. It appears that they are often composed of silicon and boron compounds, but more complex ternary or quaternary systems which include these two elements as compositional gradient materials or multilayered materials are developing. All these systems lead to some limitations of particular deposition or infiltration processes from the gas phase that are pointed out in view to some examples on the CVD and ICVI of ternary solids and multilayered materials, and on a comparison between CVD and ICVI processes for interphase elaboration. For each component of the composite, examples showing the improvement of the final properties are given. Finally we point out the domains where further research on deposition from the gas phase are needed.

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En 2025, l'explosion de l'endettement des ménages chinois est-elle une source de vulnérabilité majeure ou une évolution comparable à d'autres pays ? Réponse en graphiques et en chiffres.