Aperiodic tilings of manifolds of intermediate growth

We give a homological construction of aperiodic tiles for certain open Riemannian surfaces admitting actions of Grigorchuk groups of intermediate growth.Comment: Accepted for publication in Groups, Geometry and Dynamic

Strong chromatic index of sparse graphs

A coloring of the edges of a graph $G$ is strong if each color class is an induced matching of $G$. The strong chromatic index of $G$, denoted by $\chi_{s}^{\prime}(G)$, is the least number of colors in a strong edge coloring of $G$. In this note we prove that $\chi_{s}^{\prime}(G)\leq (4k-1)\Delta (G)-k(2k+1)+1$ for every $k$-degenerate graph $G$. This confirms the strong version of conjecture stated recently by Chang and Narayanan [3]. Our approach allows also to improve the upper bound from [3] for chordless graphs. We get that $$ for any chordless graph $G$. Both bounds remain valid for the list version of the strong edge coloring of these graphs

Security in HPC Centres

Securing the HPC infrastructure is an important task. The level of awareness regarding the importance of this topic is high, but the level of investments and skills required to organise a proper protection make it a difficult task, with contrasted levels of solutions and practices observed. There are a huge number of security threats coming from both the Internet and internal networks and, despite the fact that it may seem as a high cost, it is crucial to introduce an adequate level of security to the infrastructure, because the costs of losing data are usually much higher. Based on a survey of the PRACE community, this paper describes security technologies used in data centres and especially its subset, i.e. HPC centres. It gives a set of general recommendations concerning how to enhance security of the HPC infrastructure

Taming L\'evy flights in confined crowded geometries

We study a two-dimensional diffusive motion of a tracer particle in restricted, crowded anisotropic geometries. The underlying medium is the same as in our previous work [J. Chem. Phys. 140, 044706 (2014)] in which standard, gaussian diffusion was studied. Here, a tracer is allowed to perform Cauchy random walk with uncorrelated steps. Our analysis shows that presence of obstacles significantly influences motion, which in an obstacle-free space would be of a superdiffusive type. At the same time, the selfdiffusive process reveals different anomalous properties, both at the level of a single trajectory realization and after the ensemble averaging. In particular, due to obstacles, the sample mean squared displacement asymptotically grows sublinearly in time, suggesting non-Markov character of motion. Closer inspection of survival probabilities indicates however that underlying diffusion is memoryless over long time scales despite strong inhomogeneity of motion induced by orientational ordering.Comment: 9 pages, 10 figure

Word associations of bilingual speakers of the languages: Polish and Italian

This article is an attempt to explain the basic rules of word associacions of bilingual speakers as well as the matter of the second language acquisition with its cultural implications. The paper deals also with the matter of lexical access with particular stress put on the theory of connectionism. The study is based on the free word association test and was conducted with cooperation with a group of Polish students of the Italian language. The results show a significant correlation between learning a second language and acquiring the culture of its geographic area. This article is an attempt to explain the basic rules of word associacions of bilingual speakers as well as the matter of the second language acquisition with its cultural implications. The paper deals also with the matter of lexical access with particular stress put on the theory of connectionism. The study is based on the free word association test and was conducted with cooperation with a group of Polish students of the Italian language. The results show a significant correlation between learning a second language and acquiring the culture of its geographic area.

Effective interaction scale of large pTp_{T} hadron production beyond leading order in QCD

The scale dependance of large $p_{T}$ hadron production is investigated and analyzed in terms of double moments for qq $\to$ qX and qq $\to$ gX partonic subprocesses in the next-to-leading order. Calculated here qq $\to$ gX cross-section turns out to be small in comparison with quark fragmentation contribution and is shown not to influence the interaction scale extracted according to the fastest apparent convergence criterio

How to measure greenness? : metrics in green chemistry

The presentation delves into the metrics used to assess the "greenness" of chemical procedures and processes, categorizing them into two primary segments. The first, "Simple Greenness Indicators", are quantitative parameters derived from empirical or estimated data, offering insights into environmental impacts such as waste generation, energy consumption, or hazardous substance involvement. Especially, the Chlortox scale is introduced as a significant metric to gauge the toxicity of substances. The second segment encompasses "Models", intricate tools providing a holistic view of greenness by considering multiple criteria. Notable models include the Green Analytical Procedures Index (GAPI), its complex variant ComplexGAPI, the Analytical GREEnness metric approach (AGREE), and AGREEprep, which focuses on sample preparation. The RGB model stands out, with Red representing performance, Green symbolizing sustainability, and Blue indicating practical and economic criteria. This presentation serves as a valuable resource for academic teachers, offering a structured approach to seamlessly integrate the metrics of green chemistry into the curriculum, thereby fostering a deeper understanding and commitment to sustainable practices in the next generation of chemists

Delineating elastic properties of kinesin linker and their sensitivity to point mutations

We analyze free energy estimators from simulation trials mimicking single-molecule pulling experiments on a neck linker of a kinesin motor. For that purpose, we have performed a version of steered molecular dynamics (SMD) calculations. The sample trajectories have been analyzed to derive distribution of work done on the system. In order to induce stretching of the linker, we have applied a constant pulling force to the molecule and allowed for a subsequent relaxation of its structure. The use of fluctuation relations (FR) relevant to non-equilibrium systems subject to thermal fluctuations allows us to assess the difference in free energy between stretched and relaxed conformations. To further understand effects of potential mutations on elastic properties of the linker, we have performed similar in silico studies on a structure formed of a polyalanine sequence (Ala-only) and on three other structures, created by substituting selected types of amino acid residues in the linker’s sequence with alanine (Ala) ones. The results of SMD simulations indicate a crucial role played by the Asparagine (Asn) and Lysine (Lys) residues in controlling stretching and relaxation properties of the linker domain of the motor

The effect of a water dam on Lake Powidzkie and its vicinity

The paper presents an attempt of assessment of the effect of damming of lakes on water resources based on the example of Lake Powidzkie (Central Poland) and its catchment. The analysed object is located in a region with the greatest water deficits in Poland. A co-occurrence of unfavourable natural and anthropogenic factors contributed to a considerable reduction of water resources retained in the discussed lake. Particularly low water levels were recorded in the 1990's and in the first decade of the 21st century. The situation was not improved by a water dam constructed on the outflow from the lake in the 1960's, among others due to neglect in its exploitation. Owing to the modernisation of the dam in 2010 and favourable hydrological situation in winter 2011, it was possible to retain excess water and substantially reduce its outflow. The restoration of the lost water resources, and hydrological benefits resulting from the fact were still observed several years later. Problems related to water deficits are becoming increasingly common in many regions of the world. A solution mitigating such a situation can be among others damming natural lakes. It is simpler, cheaper, and less invasive for the environment than the construction of new water reservoirs