On the inclusive gluon jet production from the triple pomeron vertex in the perturbative QCD

Single and double inclusive cross-sections for gluon jet production from within the triple pomeron vertex are studied in the reggeized gluon technique. It is shown that to satisfy the AGK rules the vertex has to be fully symmetric in all four reggeized gluons which form the two final pomerons. The single inclusive cross-sections are found for different cuttings of the triple pomeron vertex. They sum into the expression obtained by Yu.Kovchegov and K.Tuchin in the colour dipole picture. The found double inclusive cross-sections satisfy the AGK rules.Comment: 17 pages in LaTex, 6 figures, revised version with partially changed rsult

Planktonic communities and chaotic advection in dynamical models of Langmuir circulation

A deterministic mechanism for the production of plankton patches within a typical medium scale oceanic structure is proposed and investigated. By direct numerical simulation of a simple model of Langmuir circulation we quantify the effects of unsteady flows on planktonic communities and demonstrate their importance. Two qualitatively different zones within the flow are identified: chaotic regions that help to spread plankton and locally coherent regions, that do not mix with the chaotic regions and which persist for long periods of time. The relative importance of these regions to both phytoplankton and zooplankton is investigated, taking into account variations in plankton buoyancy. In particular, species-specific retention zone structure is discussed in relation to variations in environmental forcing

Effects of elevated temperature on physical and mechanical properties of carbonate rocks in South-Southern Nigeria

Purpose. Limestone and marble are carbonate rocks with several structural and engineering applications. The physical and mechanical properties of the rocks are fundamental as they determine their suitability for various use. Temperature is one of the critical factors that could affect the properties of the rocks and consequently their engineering application. Therefore, a better understanding of how the temperature, especially when it is higher than ambient, will affect the properties of the rocks is essential. In this work, the effects of the elevated temperature on some physical and mechanical properties of the carbonate rocks have been studied. Methods. Cubic samples of the rocks were prepared and heated in a furnace to different temperatures up to 900°C at an interval of 100°C and then cooled to the room temperature for testing. Porosity, dry density and uniaxial compressive strength (UCS) of the samples were determined under the effect of the elevated temperature. The porosity and dry density were determined using the saturation and buoyancy method while the UCS was estimated from the point load index tests performed on the samples. Findings. The results of this work indicate that the elevated temperature has significant effects on the physical and mechanical properties of the rocks. The porosity of the rocks showed an increasing trend as the temperature was increased while the density steadily decreased especially at the temperature above 300°C. The UCS of the rocks also declines with increased temperature but with an intermittent increase in their strength at a specific heating temperature. Originality. Most of the available studies on Nigerian carbonate rocks are focused on the estimation of physical and mechanical properties of the rocks without considering changes in these properties when the rocks are subjected to high temperatures. This study therefore aims to fill the gap by investigating the effects of the elevated temperatures on the physical and mechanical properties of some of the Nigerian carbonate rocks. Practical implications. The results of this study further increase understanding of the effect of high temperature on carbonate rocks, and also help to identify the critical temperature at which the properties of carbonate rocks undergo significant and irreversible changes. This information is very important for restoration of valuable fire-damaged structures made of carbonate rocks.Мета. Вивчення впливу високих температур на фізико-механічні властивості карбонатних порід на основі експериментальних термічних досліджень їх зразків для проектування будівель і споруд, стійких до руйнувань від пожеж. Методика. Кубічні зразки порід нагрівалися в печі до 900°C з інтервалом у 100°C, а потім охолоджувалися до кімнатної температури. Пористість, об’ємна маса в сухому стані, міцність на одноосьовий стиск (МОС) зразків визначалися при різних високих температурах. Пористість та об’ємна маса в сухому стані вимірювалися шляхом визначення насичення й плавучості зразків, у той час як МОС оцінювалася при випробуванні зразків на зосереджене навантаження. Результати. Результати дослідження свідчать про те, що високі температури чинять суттєвий вплив на фізико-механічні властивості карбонатних порід. З підвищенням температури пористість порід має стійку тенденцію до збільшення, а об’ємна маса – до зменшення, особливо при температурах вище 300°C. МОС також в цілому знижується при підвищенні температури, однак при деяких температурах спостерігається тимчасове збільшення міцності. Наукова новизна. Вперше для карбонатних порід Нігерії встановлено характер впливу високих температур на їх фізико-механічні властивості, що раніше не досліджувалось. Дане дослідження проведено з метою заповнення прогалини у вивченні цього питання. Практична значимість. Розширено уявлення щодо впливу високих температур на карбонатні породи та визначено критичні значення температури, при яких їх властивості зазнають суттєвих і незворотніх змін. Ці дані є досить важливими для відновлення значущих споруд із карбонатних порід, які піддалися руйнуванню під час пожежі.Цель. Изучение влияния высоких температур на физико-механические свойства карбонатных пород на основе экспериментальных термических исследований их образцов для проектирования зданий и сооружений, устойчивых к разрушениям от пожаров. Методика. Кубические образцы пород нагревались в печи до 900°C с интервалом в 100°C, а затем охлаждались до комнатной температуры. Пористость, объемная масса в сухом состоянии, прочность на одноосное сжатие (ПОС) образцов определялись при различных высоких температурах. Пористость и объемная масса в сухом состоянии измерялись путем определения насыщения и плавучести образцов, в то время как ПОС оценивалась при испытании образцов на сосредоточенную нагрузку. Результаты. Результаты исследования свидетельствуют о том, что высокие температуры оказывают значительное влияние на физико-механические свойства карбонатных пород. С возрастанием температуры пористость пород имеет устойчивую тенденцию к увеличению, а объемная масса – к уменьшению, особенно при температурах выше 300°C. ПОС также в целом снижается при повышении температуры, однако при некоторых температурах наблюдается временное увеличение прочности. Научная новизна. Впервые для карбонатных пород Нигерии установлен характер влияния высоких температур на их физико-механические свойства, что ранее не исследовалось. Данное исследование проведено для заполнения пробела в изучении этого вопроса. Практическая значимость. Расширены представления о влиянии высоких температур на карбонатные породы и определены критические значения температуры, при которых их свойства претерпевают существенные и необратимые изменения. Эти данные очень важны для восстановления значимых сооружений из карбонатных пород, которые подверглись разрушению при пожаре.The author wish to express his appreciation to Mr. J.O. Ayeni, Mr. M.B. Jamiu, Mr. I.O. Olanrewaju and Mr. T.V. Oluwafemi for their contribution in acquiring the data used for this study

Residual, restarting and Richardson iteration for the matrix exponential

A well-known problem in computing some matrix functions iteratively is a lack of a clear, commonly accepted residual notion. An important matrix function for which this is the case is the matrix exponential. Assume, the matrix exponential of a given matrix times a given vector has to be computed. We interpret the sought after vector as a value of a vector function satisfying the linear system of ordinary differential equations (ODE), whose coefficients form the given matrix. The residual is then defined with respect to the initial-value problem for this ODE system. The residual introduced in this way can be seen as a backward error. We show how the residual can efficiently be computed within several iterative methods for the matrix exponential. This completely resolves the question of reliable stopping criteria for these methods. Furthermore, we show that the residual concept can be used to construct new residual-based iterative methods. In particular, a variant of the Richardson method for the new residual appears to provide an efficient way to restart Krylov subspace methods for evaluating the matrix exponential.\u

A block Krylov subspace time-exact solution method for linear ODE systems

We propose a time-exact Krylov-subspace-based method for solving linear ODE (ordinary differential equation) systems of the form $y'=-Ay + g(t)$ and $y''=-Ay + g(t)$, where $y(t)$ is the unknown function. The method consists of two stages. The first stage is an accurate piecewise polynomial approximation of the source term $g(t)$, constructed with the help of the truncated SVD (singular value decomposition). The second stage is a special residual-based block Krylov subspace method. The accuracy of the method is only restricted by the accuracy of the piecewise polynomial approximation and by the error of the block Krylov process. Since both errors can, in principle, be made arbitrarily small, this yields, at some costs, a time-exact method. Numerical experiments are presented to demonstrate efficiency of the new method, as compared to an exponential time integrator with Krylov subspace matrix function evaluations

E-commerce technology adoption framework by New Zealand small to medium size enterprises

This paper attempts to highlight a framework for the adoption of electronic commerce (EC) technologies in New Zealand with specific interest in the small to medium-size enterprise (SME) sector of the economy. The main thrust of the research was to develop the framework for EC adoption by the New Zealand SMEs and hence study the accelerators and impediments to the adoption and diffusion of EC technologies. The paper shows how IS/IT adoption and diffusion theories and practicalities can be explored for developing the proposed EC adoption framework. It is argued that results from research case studies based on the framework are able to identify the factors influencing and leading to the adoption of e-commerce technologies by the New Zealand SMEs

Higher Spin Fields in Siegel Space, Currents and Theta Functions

Dynamics of four-dimensional massless fields of all spins is formulated in the Siegel space of complex $4\times 4$ symmetric matrices. It is shown that the unfolded equations of free massless fields, that have a form of multidimensional Schrodinger equations, naturally distinguish between positive- and negative-frequency solutions of relativistic field equations, i.e. particles and antiparticles. Multidimensional Riemann theta functions are shown to solve massless field equations in the Siegel space. We establish the correspondence between conserved higher-spin currents in four-dimensional Minkowski space and those in the ten-dimensional matrix space. It is shown that global symmetry parameters of the current in the matrix space should be singular to reproduce a nonzero current in Minkowski space. The \D-function integral evolution formulae for 4d massless fields in the Fock-Siegel space are obtained. The generalization of the proposed scheme to higher dimensions and systems of higher ranks is considered.Comment: LaTeX, 38 pages, v.3: clarifications, acknowledgements and references added, typos corrected, v.4: more comments and references added, typos corrected, the version to appear in JHE

Women's attitudes toward menstruation : a quantitative survey and qualitative interview investigation : a thesis presented in partial fulfilment of the requirements for the degree of Master of Arts in Psychology at Massey University

Menstruation plays an important role in the psychology of women. There is, however, little information about the nature of women's attitudes toward menstruation. The present study used a quantitative survey followed by a series of qualitative interviews to explore these attitudes in a sample of University women in New Zealand. The Menstrual Attitude Questionnaire (MAO) was used to assess the attitudes and beliefs of 343 women. The psychometric properties of the MAO and its underlying factor structure were examined using a range of factor analytic models. Responses were then used to select a sample of 1O women for interview. Interviews were conducted in order to elaborate upon the attitudes identified by the MAO and to examine in more depth the nature of women's attitudes toward menstruation. Factor analysis of the MAO yielded five orthogonal factors. Results suggested that these university women perceived menstruation as: Marginally causing physical, emotional and intellectual changes, a natural event, an inconvenience and slightly disrupting their usual performance and activities. Subjects accepted the existence of premenstrual tension. Similarly, interviews revealed that attitudes were multidimensional with each subject having an individual configuration of positive, negative and neutral beliefs about menstruation. No consistent pattern among the different beliefs was established. Furthermore, it would appear that attitudes towards menstruation may not be acquired from direct experience but may be learned through social expectations. Directions for future research are indicated, particularly the importance of qualitative research