The social and economic bases of network multiplexity: Exploring the emergence of multiplex ties

The goal of this article is to shed light on the role of tie content in the evolution of multiplex ties – i.e., ties featuring both an economic and a social component – in interorganizational networks. The authors clarify and extend the theoretical framework on network multiplexity by testing the extent to which two distinct tie content-related logics – social interaction and economic exchange – and their underlying mechanisms lead to the emergence of multiplex ties. Results from a longitudinal network analysis of firms located in an Italian multimedia cluster support the authors’ hypotheses, confirming that both social and economic drivers contribute to the emergence of network multiplexity, and that social ties have a stronger impact than economic ties on this process, thus providing further insight into the microdynamics of network evolution

Non-collinear magnetism in freestanding and supported monatomic Mn chains

Using first-principles calculations, we study the occurrence of non-collinear magnetic order in monatomic Mn chains. First, we focus on freestanding Mn chains and demonstrate that they exhibit a pronounced non-collinear ground state in a large range of interatomic distances between atoms in the chain. By artificially varying the atomic number of Mn we investigate how the magnetic ground state is influenced by alloying the Mn chains with Fe and Cr. With increasing number of 3d-electrons we find a smooth transition in the magnetic phase space starting from an antiferromagnetic state for pure Cr chains through a regime of non-collinear ground states for Mn-rich chains to a ferromagnetic solution approaching the limit of pure Fe chains. Second, we investigate the magnetism in supported Mn chains on the (110)-surfaces of Cu, Pd, and Ag. We show that even a weak chain-surface hybridization is sufficient to dramatically change the magnetic coupling in the chain. Nevertheless, while we observe that Mn chains are antiferromagnetic on Pd(110), a weak non-collinear magnetic order survives for Mn chains on Cu(110) and Ag(110) a few meV in energy below the antiferromagnetic solution. We explain the sensitive dependence of the exchange interaction in Mn chains on the interatomic distance, chemical composition, and their environment based on the competition between the ferromagnetic double exchange and the antiferromagnetic kinetic exchange mechanism. Finally, we perform simulations which predict that the non-collinear magnetic order of Mn chains on Cu(110) and Ag(110) could be experimentally verified by spin-polarized scanning tunneling microscopy.Comment: accepted for publication by Phys. Rev.

Network pathways of peripheral firm entry: Empirical evidence from the global airline industry

Previous research on interfirm collaboration indicates that networks tend to be structurally stable due to path dependence and embedded firms' incentives to preserve their positional advantages. As a result, industry networks often resemble a core-periphery structure where peripheral firms seem to have little or no opportunity to access the core. Yet, under certain conditions, peripheral firms do manage to cross over to the industry center. In this paper, we examine one such condition: a sudden and unexpected change in the external environment. More specifically, we examine the relationship between the occurrence of an industry-level disruptive event and the dynamics of tie formation/dissolution facilitating or inhibiting peripheral firms' progress toward the center of the industry network. We substantiate our investigation by using longitudinal data on the alliance activities of 258 airlines and applying Stochastic Actor-Oriented Models (SAOM). We integrate our statistical analysis with interview material and descriptive network analysis. The findings reveal a variety of patterns of network entry, contributing novel insights to theories on network dynamics, innovation, as well as policy and practice

Essential oil composition from hop cultivated at Southern Brazil.

Edition of Abstracts of the 48th International Symposium on Essential Oils, Pécs, Hungary, 2017. Abstracts. Babedio, 2017. ISEO 2017, 10 a 13 set. 2017. P-05

Dementia-related genetic variants in an Italian population of early-onset Alzheimer’s disease

Early-onset Alzheimer’s disease (EOAD) is the most common form of early-onset dementia. Although three major genes have been identified as causative, the genetic contribution to the disease remains unsolved in many patients. Recent studies have identified pathogenic variants in genes representing a risk factor for developing Alzheimer’s disease (AD) and in causative genes for other degenerative dementias as responsible for EOAD. To study them further, we investigated a panel of candidate genes in 102 Italian EOAD patients, 45.10% of whom had a positive family history and 21.74% with a strong family history of dementia. We found that 10.78% of patients carried pathogenic or likely pathogenic variants, including a novel variant, in PSEN1, PSEN2, or APP, and 7.84% showed homozygosity for the ε4 APOE allele. Additionally, 7.84% of patients had a moderate risk allele in PSEN1, PSEN2, or TREM2 genes. Besides, we observed that 12.75% of our patients carried only a variant in genes associated with other neurodegenerative diseases. The combination of these variants contributes to explain 46% of cases with a definite familiarity and 32% of sporadic forms. Our results confirm the importance of extensive genetic screening in EOAD for clinical purposes, to select patients for future treatments and to contribute to the definition of overlapping pathogenic mechanisms between AD and other forms of dementia

A saturação por bases dos solos da Província Patamarizada na Bacia Hidrográfica Paraná III - BHP III.

Dentro da BHP III a Província Patamarizada encontra-se representada nos vales dos subplanaltos Cascavel, Campo Mourão, Foz do Iguaçu e São Francisco, sobretudo, neste último onde perfaz a grande maioria das paisagens

Ferromagnetic behavior of ultrathin manganese nanosheets

Ferromagnetic behaviour has been observed experimentally for the first time in nanostructured Manganese. Ultrathin ($\sim$ 0.6 nm) Manganese nanosheets have been synthesized inside the two dimensional channels of sol-gel derived Na-4 mica. The magnetic properties of the confined system are measured within 2K-300K temperature range. The confined structure is found to show a ferromagnetic behaviour with a nonzero coercivity value. The coercivity value remains positive throughout the entire temperature range of measurement. The experimental variation of susceptibility as a function of temperature has been satisfactorily explained on the basis of a two dimensional system with a Heisenberg Hamiltonian involving direct exchange interaction.Comment: 13 pages, 9 figure