bluuebunny/crossref_metadata_2025_split huggingface dataset:
The hyperbolicity constant of infinite circulant graphs
Authors: Rodríguez José M. , Sigarreta José M. 
Published: June 2017

Abstract
If X is a geodesic metric space and x1, x2, x3 ∈ X, a geodesic triangle T = {x1, x2, x3} is the union of the three geodesics [x1x2], [x2x3] and [x3x1] in X. The space X is δ-hyperbolic (in the Gromov sense) if any side of T is contained in a δ-neighborhood of the union of the two other sides, for every geodesic triangle T in X. Deciding whether or not a graph is hyperbolic is usually very difficult; therefore, it is interesting to find classes of graphs which are hyperbolic. A graph is circulant if it has a cyclic group of automorphisms that includes an automorphism taking any vertex to any other vertex. In this paper we prove that infinite circulant graphs and their complements are hyperbolic. Furthermore, we obtain several sharp inequalities for the hyperbolicity constant of a large class of infinite circulant graphs and the precise value of the hyperbolicity constant of many circulant graphs. Besides, we give sharp bounds for the hyperbolicity constant of the complement of every infinite circulant graph.
Coupled fixed point theorems in complete metric spaces endowed with a directed graph and application
Authors: Kir Mehmet , Yolacan Esra , Kiziltunc Hukmi 
Published: June 2017

Abstract
The purpose of this paper is to present some existence results for coupled fixed point of a (φ,ψ) —contractive condition for mixed monotone operators in metric spaces endowed with a directed graph. Our results generalize the results obtained by Jain et al. in (International Journal of Analysis, Volume 2014, Article ID 586096, 9 pages). Moreover, we have an application to some integral system to support the results.
Existence of entropy solutions for nonlinear elliptic degenerate anisotropic equations
Authors: Gorban Yuliya 
Published: June 2017

Abstract
In the present article we deal with the Dirichlet problem for a class of degenerate anisotropic elliptic second-order equations with L1-right-hand sides in a bounded domain of ℝn(n ⩾ 2) . This class is described by the presence of a set of exponents q1,…, qn and a set of weighted functions ν1,…, νn in growth and coercitivity conditions on coefficients of the equations. The exponents qi characterize the rates of growth of the coefficients with respect to the corresponding derivatives of unknown function, and the functions νi characterize degeneration or singularity of the coefficients with respect to independent variables. Our aim is to investigate the existence of entropy solutions of the problem under consideration.
Linear dynamics of semigroups generated by differential operators
Authors: Alberto Conejero J. , Lizama Carlos , Murillo-Arcila Marina , Peris Alfredo 
Published: June 2017

Abstract
During the last years, several notions have been introduced for describing the dynamical behavior of linear operators on infinite-dimensional spaces, such as hypercyclicity, chaos in the sense of Devaney, chaos in the sense of Li-Yorke, subchaos, mixing and weakly mixing properties, and frequent hypercyclicity, among others. These notions have been extended, as far as possible, to the setting of C0-semigroups of linear and continuous operators.
We will review some of these notions and we will discuss basic properties of the dynamics of C0-semigroups. We will also study in detail the dynamics of the translation C0-semigroup on weighted spaces of integrable functions and of continuous functions vanishing at infinity. Using the comparison lemma, these results can be transferred to the solution C0-semigroups of some partial differential equations. Additionally, we will also visit the chaos for infinite systems of ordinary differential equations, that can be of interest for representing birth-and-death process or car-following traffic models.
Features of the structural and magnetic properties of Pb(TixZr1–xO3)-NiFe1.98Co0.02O4 in the polarized state
Authors: Baev Vadim , Budzyński Mieczysław , Laletin Vladimir , Mitsiuk Victor , Poddubnaya Natali , Surowiec Zbigniew , Yanushkevich Kazimir 
Published: June 2017

Abstract
Composites with a 90%Pb(TixZr1-xO3)-10%NiFe1.98Co0.02O4 composition have been synthesized. It has been established that the polarization of samples resulting from exposure to an electric field for 1 hour of 4 kV/mm in strength at a temperature of 400 K leads to crystal structure deformation. The compression of elementary crystal cells in some areas during polarization of the sample creates conditions suitable for the enhancement of magnetic exchange interactions. It has been found that the polarization process of such compositions leads to increases in specific magnetization and magnetic susceptibility. The analysis of Mössbauer spectra has shown that the polarization of the 90%Pb(TixZr1-xO3)-10%NiFe1.98Co0.02O4 composite leads to significant changes in the effective magnetic fields of iron subspectra in various positions.
Thermodynamic properties of dilute Co-Fe solid solutions studied by 57Fe Mössbauer spectroscopy
Authors: Konieczny Robert , Idczak Rafał 
Published: June 2017

Abstract
The Co1-xFex alloys where x ranges from 0.01 to 0.06 were measured at room temperature using transmission Mössbauer spectroscopy (TMS). The analysis of the obtained data allowed the determination of the short-range order (SRO), the binding energy Eb between two iron atoms in the studied materials using the extended Hrynkiewicz-Królas idea and the enthalpy of solution HCo-Fe of Fe in Co. The results showed that the Fe atoms dissolved in a Co matrix interact repulsively and the estimated value of HCo-Fe = -0.166(33) eV/atom. Finally, values of the enthalpy of solution were used to predict the enthalpy of mixing for the Co-Fe system. These findings were compared with corresponding data given in the literature, which were derived from calorimetric experiments and from the cellular atomic model of alloys described by Miedema.
Mössbauer and heat capacity studies of ErZnSn2
Authors: Łątka Kazimierz , Przewoźnik Janusz , Żukrowski Jan , Verbovytskyy Yuriy , Gonçalves Antonio Pereira 
Published: June 2017

Abstract
Heat capacity results obtained for the intermetallic compound ErZnSn2 were re-analysed to also consider, apart from the classical Debye model, the anharmonicity of the crystal lattice and the proper set of Einstein modes. The 119mSn Mössbauer technique was applied to derive the hyperfine interaction parameters characteristic of the two inequivalent crystallographic Sn sites in the compound studied. Quadrupole interaction constants, as measured by 119mSn Mössbauer spectroscopy, allowed for estimations of Vzz components of the electric field gradient tensor that exist at both Sn sites in the discussed compound.
A comparative study of hyperfine interactions in Aurivillius compounds prepared by mechanical activation and solid-state sintering
Authors: Mazurek Mariusz , Jartych Elżbieta 
Published: June 2017

Abstract
X-ray diffraction and Mössbauer spectroscopy techniques were used to study the structure and hyperfine interactions of multiferroic Aurivillius compounds Bim+1Ti3Fem-3O3m+3. Samples were synthesized by two methods, that is, the solid-state sintering at various temperatures and mechanical activation in a high-energy ball mill. The compounds were obtained from a mixture of three polycrystalline powder oxides, that is, TiO2, Fe2O3 and Bi2O3. At room temperature, the Aurivillius compounds are paramagnetic materials with orthorhombic crystal structure. The c lattice parameter of the unit cell depends linearly on the m − number of layers with perovskite-like structure. Based on the Mössbauer studies, it is concluded that the hyperfine interactions parameters do not change with m number.
Crystal structure and Mössbauer effect in multiferroic 0.5BiFeO3-0.5Pb(Fe0.5Ta0.5)O3 solid solution
Authors: Stoch Agata , Maurin Jan , Stoch Paweł , Kulawik Jan , Szwagierczak Dorota 
Published: June 2017

Abstract
Multiferroic 0.5BiFeO3-0.5Pb(Fe0.5Ta0.5)O3 solid solution is a material that exhibits ferroelectric and antiferromagnetic orderings in ambient temperature. The solid solution was obtained as a result of a conventional reaction in a solid state. The obtained material is a dense, fine-grained sinter whose surface was observed by scanning electron microscopy (SEM) and stoichiometry was confirmed by energy dispersive X-ray spectroscopic (EDS) analysis. According to the X-ray powder diffraction (XRD) measurements, the main phase is R3c space group with admixture of Pm-3m regular phase. Small contribution of pyrochlore-like phase was also observed. Mössbauer spectroscopy suggested random distribution of Fe3+/Ta5+ cations in the B sites of ABO3 compound. Reduction of the magnetic hyperfine field with an increase in the substitution of Ta5+ in Fe3+ neighbourhood was also observed.
Investigation of magnetite Fe3O4 nanoparticles for magnetic hyperthermia
Authors: Surowiec Zbigniew , Miaskowski Arkadiusz , Budzyński Mieczysław 
Published: June 2017

Abstract
The paper presents the investigation of magnetic nanoparticles (MNPs) dedicated to hyperthermia application. The crystal structure and size distributions have been determined by means of transmission electron microscope (TEM) and X-ray diffraction (XRD). Magnetic properties of the nanoparticles were tested by Mössbauer spectroscopy together with calorimetric experiments. The Mössbauer spectroscopic study of MNPs revealed the existence of a superparamagnetic phase. The relative contribution of the relaxing component to the total spectrum at room temperature was about 10%. The heating effect of these MNPs under alternating magnetic field was examined. The temperature increase has reached 5°C in 10 min. The preliminary temperature rise suggests that the investigated materials are applicable for hyperthermia.
Iron-containing phases in metallurgical and coke dusts as well as in bog iron ore
Authors: Szumiata Tadeusz , Rachwał Marzena , Magiera Tadeusz , Brzózka Katarzyna , Gzik-Szumiata Małgorzata , Gawroński Michał , Górka Bogumił , Kyzioł-Komosińska Joanna 
Published: June 2017

Abstract
Several samples of dusts from steel and coke plants (collected mostly with electro filters) were subjected to the investigation of content of mineral phases in their particles. Additionally, sample of bog iron ore and metallurgical slurry was studied. Next, the magnetic susceptibility of all the samples was determined, and investigations of iron-containing phases were performed using transmission Mössbauer spectrometry. The values of mass-specific magnetic susceptibility χ varied in a wide range: from 59 to above 7000 × 10−8 m-3·kg−1. The low values are determined for bog iron ore, metallurgical slurry, and coke dusts. The extremely high χ was obtained for metallurgical dusts. The Mössbauer spectra and X-ray diffraction patterns point to the presence of the following phases containing iron: hematite and oxidized magnetite (in coke and metallurgical dusts as well as metallurgical slurry), traces of magnetite fine grains fraction (in metallurgical dusts), amorphous glassy silicates with paramagnetic Fe3+ and Fe2+ ions, traces of pyrrhotite (in coke dusts), α-Fe and nonstoichiometric wüstite (in metallurgical slurry), as well as ferrihydrite nanoparticles (in bog iron ore). For individual samples of metallurgical dusts, the relative contributions of Fe2+/3+ ions in octahedral B sites and Fe2+ ions in tetrahedral A sites in magnetite spinel structure differs considerably.
Abiotic stress tolerance of microorganisms associated with oregano (Origanum vulgare L.) in the Yaqui Valley, Sonora
Authors: Meléndez Mariel García , Camargo Geovanna Zárate , Meza Contreras Jenny Jocabet , Sepúlveda Angélica Herrera , Santos Villalobos Sergio de los , Parra Cota Fannie Isela 
Published: June 2017

Abstract
The impact of agricultural activities on microbial communities and environmental parameters was evaluated in two different soil samples. One sample corresponded to soil designated to oregano cultivation and the other one to native soil, both located in the Yaqui Valley, Sonora. The objective of this study was to estimate the microbial diversity in both soil samples, evaluating isolates obtained under three stress conditions: temperature, salinity and pesticide resistance, as well as using metabolic tests to evaluate their potential capabilities as plant growth promoting bacteria. The bacterial population was 5.9×106 and 3.8×106 CFU/g dry soil, in the native and oregano-designated soil, respectively. A total of twenty-four bacteria and one actinobacterium were isolated. Native soil microorganisms presented higher values for fungicide tolerance and indoleacetic acid production; however, temperature stress, salinity resistance, siderophore production and phosphate solubilization were higher for microorganisms isolated from the agricultural soil. These results demonstrate the impact of land use on microbial communities and their potential eco-functional roles.
Generating Questions: Processing Time Changes Between Early Adolescence and Young Adulthood
Authors: Drumm Patrick , Jackson Dorothy W. 
Published: June 2017

Abstract
Information seeking by asking questions is fundamental to solving some problems. How quickly it proceeds can be important, especially if stakes are high. This experiment compared the processing times of three question types generated by early adolescents, middle adolescents, and young adults who sought to identify unknown target exemplars in a series of test arrays. Category questions, which eliminate alternatives based on their membership in contrasting mutually exclusive sets, were of two types: conceptual and perceptual. Conceptual category questions took longer to generate than perceptual category questions for all age groups. Syncretic questions, which refer to more than one category, took longer to generate than perceptual category questions for early adolescents, although they did not take longer to generate than perceptual category questions for the two older groups. Age-related changes in cognitive processing, syncretic thinking, and experience with hypothesis testing provide a framework for interpreting these results.
Designing Peg Solitaire Puzzles
Authors: Bell George I. 
Published: June 2017

Abstract
Peg solitaire is an old puzzle with a 300 year history. We consider two ways a computer can be utilized to find interesting peg solitaire puzzles. It is common for a peg solitaire puzzle to begin from a symmetric board position, we have computed solvable symmetric board positions for four board shapes. A new idea is to search for board positions which have a unique starting jump leading to a solution. We show many challenging puzzles uncovered by this search technique. Clever solvers can take advantage of the uniqueness property to help solve these puzzles.
Exploring the “Rubik's Magic” Universe
Authors: Paolini Maurizio 
Published: June 2017

Abstract
By using two different invariants for the Rubik’s Magic puzzle, one of metric type, the other of topological type, we can dramatically reduce the universe of constructible configurations of the puzzle. Finding the set of actually constructible shapes remains however a challenging task, that we tackle by first reducing the target shapes to specific configurations: the octominoid 3D shapes, with all tiles parallel to one coordinate plane; and the planar “face-up” shapes, with all tiles (considered of infinitesimal width) lying in a common plane and without superposed consecutive tiles. There are still plenty of interesting configurations that do not belong to either of these two collections. The set of constructible configurations (those that can be obtained by manipulation of the undecorated puzzle from the starting situation) is a subset of the set of configurations with vanishing invariants. We were able to actually construct all octominoid shapes with vanishing invariants and most of the planar “face-up” configurations. Particularly important is the topological invariant, of which we recently found mention in [7] by Tom Verhoeff.
On a Mathematical Model for an Old Card Trick
Authors: Quintero Roy 
Published: June 2017

Abstract
The three-pile trick is a well-known card trick performed with a deck of 27 cards which dates back to the early seventeenth century at least and its objective is to uncover the card chosen by a volunteer. The main purpose of this research is to give a mathematical generalization of the three-pile trick for any deck of ab cards with a, b ≥ 2 any integers by means of a finite family of simple discrete functions. Then, it is proved each of these functions has just one or two stable fixed points. Based on this findings a list of 222 (three-pile trick)-type brand new card tricks was generated for either a package of 52 playing cards or any appropriate portion of it with a number of piles between 3 and 7. It is worth noting that all the card tricks on the list share the three main properties that have characterized the three-pile trick: simplicity, self-performing and infallibility. Finally, a general performing protocol, useful for magicians, is given for all the cases. All the employed math techniques involve naive theory of discrete functions, basic properties of the quotient and remainder of the division of integers and modular arithmetic.
Eternal Picaria
Authors: Larsson Urban , Rocha Israel 
Published: June 2017

Abstract
Picaria is a traditional board game, played by the Zuni tribe of the American Southwest and other parts of the world, such as a rural Southwest region in Sweden. It is related to the popular children’s game of Tic-tac-toe, but the 2 players have only 3 stones each, and in the second phase of the game, pieces are slided, along specified move edges, in attempts to create the three-in-a-row. We provide a rigorous solution, and prove that the game is a draw; moreover our solution gives insights to strategies that players can use.
Understanding Student Motivation: A Key to Retention in Higher Education
Authors: Rizkallah Elias G. , Seitz Victoria 
Published: June 2017

Abstract
This paper explores what motivates college students at different stages of their academic studies. Using Herzberg’s two-factor theory, the researchers conducted a survey of 535 students in three south-western universities to determine if motivations changed throughout their academic careers. Results showed that students at different stages of their college careers have different concerns and, as such, different motivational strategies are needed to respond to their concerns. Implications are given to grow and retain enrolment.
The Effect of Credit Risk and Capital Adequacy on the Profitability of Rural Banks in the Philippines
Authors: Mendoza Rufo , Rivera John Paolo R. 
Published: June 2017

Abstract
This paper examines the credit risk and capital adequacy of the 567 rural banks in the Philippines to investigate how both variables affect bank profitability. Using the Arellano-Bond estimator, we found out that credit risk has a negative and statistically significant relationship with profitability. However, empirical analysis showed that capital adequacy has no significant impact on the profitability of rural banks in the Philippines. It is therefore necessary for the rural banks to examine more deeply if capital infusion would result in higher profitability than increasing debts. The study also implies that it is imperative for the banks to understand which risk factors have greater impact on their financial performance and use better risk-adjusted performance measurement to support their strategies. Rural banks should establish credit risk management that defines the process from initiation to approval of loans, taking into consideration the sound credit risk management practices issued by regulatory bodies. Moreover, rural banks need to enhance internal control measures to ensure the strict implementation of internal processes on lending operations.
Trade Credit Insurance and Asymmetric Information Problem
Authors: Sokolovska Olena 
Published: June 2017

Abstract
The presence of different risk factors in international trade gives evidence of the necessity of support in gaps that may affect exporters’ activity. To maximize the trade volumes and in the same time to minimize the exporters’ risks the stakeholders use trade credit insurance. The paper provides analysis of conceptual background of the trade credit insurance in the world. We analyzed briefly the problems, arising in insurance markets due to asymmetric information, such as adverse selection and moral hazard. Also we discuss the main stages of development of trade credit insurance in countries worldwide. Using comparative and graphical analysis we provide a brief evaluation of the dynamics of claims and recoveries for different forms of trade credit insurance. We found that the claims related to the commercial risk for medium and long trade credits in recent years exceed the recoveries, while with the political risk the reverse trend holds. And we originally consider these findings in terms of information asymmetry in the trade credit insurance differentiated by type of risk.
Impact of Entertainment Motivational Drivers on User Acceptance of Online Social Network Banner Advertising: A Gratification Perspective
Authors: Mir Imran Anwar 
Published: June 2017

AbstractSocial media has phenomenally changed the communication landscape. Particularly social network sites have received enormous popularity and user acceptance globally. The business model of many social network sites is based on advertising. The survival of these social network sites depends on the user acceptance of advertising appearing on these websites. Users usually accept the advertising which is consistent with their motivations for using social network sites. The current study examines the underlying dimensions of entertainment motivation for using social network sites and their impact on user acceptance of social network advertising. Analysis of data from 450 university students show entertainment motivation for using social network sites a multidimensional (SNSs) construct consisting of enjoyment, social escapism, relaxation and pass time factors. Furthermore, the results exhibit that SNSs entertainment motivation partially impacts user acceptance of social network advertising.
Emissions Trading for Cleaner Production in the Old and New EU Member States?
Authors: Krištić Irena Raguž 
Published: June 2017

AbstractThis paper examines the success of the European Union Emissions Trading System (EU ETS) in inducing cleaner production in the EU based on the first two trading periods. It fills a literature gap by constructing a measure of clean production and conducting an ex-post macro-level analysis of the EU ETS impacts in EU15 compared to EU12. Results of panel regression analysis robustly show that EU ETS in both EU12 and EU15 (i) has positive impact on clean production of regulated industries, (ii) does not induce spillovers of cleaner technologies and processes to non-regulated industries, and (iii) does not affect clean production at the national level. In addition, share of renewables in energy consumption has a positive and crisis a negative impact on the clean production. Results support further tightening and broader coverage of EU ETS regulation and provision of funds from the EU ETS for development of renewable energy technologies.