The preferential binding of anions and cations in aqueous solutions of the ionic liquids (ILs) 1-butyl- 3-methylimidazolium ([C₄mim]⁺) and 1-ethyl-3-methylimidazolium ([C₂mim]⁺) chloride and dicyanamide (dca^-) with the small alpha-helical protein Im7 was investigated using a combination of differential scanning calorimetry, NMR spectroscopy and molecular dynamics (MD) simulations. Our results show that direct ion interactions are crucial to understand the effects of ILs on the stability of proteins and that an anion effect is dominant. We show that the binding of weakly hydrated anions to positively charged or polar residues leads to the partial dehydration of the backbone groups, and is critical to control stability, explaining why dca^- is more denaturing than Cl^-. Direct cation–protein interactions also mediate stability; cation size and hydrophobicity are relevant to account for destabilisation as shown by the effect of [C₄mim]⁺ compared to [C₂mim]⁺. The specificity in the interaction of IL ions with protein residues established by weak favourable interactions is confirmed by NMR chemical shift perturbation, amide hydrogen exchange data and MD simulations. Differences in specificity are due to the balance of interaction established between ion pairs and ion-solvent that determine the type of residues affected. When the interaction of both cation and anion with the protein is strong the net result is similar to a non-specific interaction, leading ultimately to unfolding. Since the nature of the ions is a determinant of the level of interaction with the protein towards denaturation or stabilisation, ILs offer a unique possibility to modulate protein stabilisation or even folding events.

Let \(\mathcal{M}(\mathbb{R}^n)\) be the class of bounded away from one and infinity functions \(p:\mathbb{R}^n\to[1,\infty]\) such that the Hardy-Littlewood maximal operator is bounded on the variable Lebesgue space \(L^{p(\cdot)}(\mathbb{R}^n)\). We show that if \(a\) belongs to the Hörmander class \(S_{\rho,\delta}^{n(\rho-1)}\) with \(0<\rho\le 1\), \(0\le\delta<1\), then the pseudodifferential operator \(\operatorname{Op}(a)\) is bounded on the variable Lebesgue space \(L^{p(\cdot)}(\mathbb{R}^n)\) provided that \(p\in\mathcal{M}(\mathbb{R}^n)\). Let \(\mathcal{M}^*(\mathbb{R}^n)\) be the class of variable exponents \(p\in\mathcal{M}(\mathbb{R}^n)\) represented as \(1/p(x)=\theta/p_0+(1-\theta)/p_1(x)\) where \(p_0\in(1,\infty)\), \(\theta\in(0,1)\), and \(p_1\in\mathcal{M}(\mathbb{R}^n)\). We prove that if \(a\in S_{1,0}^0\) slowly oscillates at infinity in the first variable, then the condition \[ \lim_{R\to\infty}\inf_{|x|+|\xi|\ge R}|a(x,\xi)|>0 \] is sufficient for the Fredholmness of \(\operatorname{Op}(a)\) on \(L^{p(\cdot)}(\mathbb{R}^n)\) whenever \(p\in\mathcal{M}^*(\mathbb{R}^n)\). Both theorems generalize pioneering results by Rabinovich and Samko [RS08] obtained for globally log-Hölder continuous exponents \(p\), constituting a proper subset of \(\mathcal{M}^*(\mathbb{R}^n)\).

n/a

n/a

n/a

n/a

Spreadsheets are being used with many different purposes that range from toy applications to complete information systems. In any of these cases, they are often used as data repositories that can grow significantly. As the amount of data grows, it also becomes more difficult to extract concrete information out of them. This paper focuses on the problem of spreadsheet querying. In particular, we propose an expressive and composable technique where intuitive queries can be defined. Our approach builds on a model-driven spreadsheet development environment, and queries are expressed referencing entities in the model of a spreadsheet instead of in its actual data. Finally, the system that we have implemented relies on Google's query function for spreadsheets.

This paper presents a tool, named QUERYSHEET, to query spreadsheets. We defined a language to write the queries, which resembles SQL, the language to query databases. This allows to write queries which are more related to the spreadsheet content than with current approaches.

Let k be a positive integer and G be a k-connected graph. An edge-coloured path is rainbow if its edges have distinct colours. The rainbow k-connection number of G, denoted by rc_k(G), is the minimum number of colours required to colour the edges of G so that any two vertices of G are connected by k internally vertex-disjoint rainbow paths. The function rc_k(G) was first introduced by Chartrand, Johns, McKeon, and Zhang in 2009, and has since attracted considerable interest. In this paper, we consider a version of the function rc_k(G) which involves vertex-colourings. A vertex-coloured path is vertex-rainbow if its internal vertices have distinct colours. The rainbow vertex k-connection number of G, denoted by rvc_k(G), is the minimum number of colours required to colour the vertices of G so that any two vertices of G are connected by k internally vertex-disjoint vertex-rainbow paths. We shall study the function rvc_k(G) when G is a cycle, a wheel, and a complete multipartite graph. We also construct graphs G where rc_k(G) is much larger than rvc_k(G) and vice versa so that we cannot in general bound one of rc_k(G) and rvc_k(G) in terms of the other.

We introduce a class of finite semigroups obtained by considering Rees
quotients of numerical semigroups.
Several natural questions concerning this class, as well as particular
subclasses obtained by considering some special ideals, are answered while
others remain open. We exhibit nice presentations for these semigroups and
prove that the Rees quotients by ideals of N, the positive integers under
addition, constitute a set of generators for the pseudovariety of commutative
and nilpotent semigroups.

Os sistemas de memória transacional distribuída atuais recorrem essencialmente à distribuição ou à replicação total para distribuir os seus dados pelos múltiplos nós do sistema. No entanto, estas estratégias de replicação de dados apresentam limitações. A distribuição não oferece tolerância a falhas e a replicação total limita a capacidade de armazenamento do sistema. Nesse contexto, a replicação parcial de dados surge como uma solução intermédia, que combina o melhor das duas anteriores com o intuito de mitigar as suas desvantagens. Esta estratégia tem sido explorada no contexto das bases de dados distribuídas, mas tem sido pouco abordada no contexto da memória transacional e, tanto quanto sabemos, nunca antes tinha sido incorporada num sistema de memória transacional distribuída para uma linguagem de propósito geral. Assim, neste artigo propomos e avaliamos uma infraestrutura para replicação parcial de dados para programas Java bytecode, que foi desenvolvida com base num sistema já existente de memória transacional distribuída. A modularidade da infraestrutura que apresentamos permite a implementação de múltiplos algoritmos e, por conseguinte, avaliar em que contextos de utilização (workloads, número de nós, etc.) a replicação parcial se apresenta como uma alternativa viável a outras estratégias de replicação de dados.

The present paper presents a physical prototype that simulates the response of a single degree of freedom dynamic system, equipped with a novel semi-active vibration control device. This device comprises two superelastic NiTi elements working in phase opposition and aims to prevent deck unseating in simply supported bridges, during a seismic excitation. The special design of this device allows to avoid problems related to stress–relaxation phenomena and material degradation because of cyclic loading that have been observed in similar passive dissipation devices. The proposed design uses a strategy that permits the continuous adapting of the accumulated stress in the NiTi wires, on the basis of the response of the device to external excitations. Although unloaded, the NiTi elements remain strain/stress free, preventing stress–relaxation phenomena. With the occurrence of a dynamic excitation, a cumulative strain/stress process in the superelastic wires is initiated, enabling higher martensite transformation ratios and therefore increasing the damping capacities of the system while keeping the stresses in the wires inside a narrower superelastic window. The strain/stress accumulation in the superelastic wires is a direct result of the motion of the structure itself, with no need for external energy input.