Theory of freezing in simple systems

The transition parameters for the freezing of two one-component liquids into crystalline solids are evaluated by two theoretical approaches. The first system considered is liquid sodium which crystallizes into a body-centered-cubic (bcc) lattice; the second system is the freezing of adhesive hard spheres into a face-centered-cubic (fcc) lattice. Two related theoretical techniques are used in this evaluation: One is based upon a recently developed bifurcation analysis; the other is based upon the theory of freezing developed by Ramakrishnan and Yussouff. For liquid sodium, where experimental information is available, the predictions of the two theories agree well with experiment and each other. The adhesive-hard-sphere system, which displays a triple point and can be used to fit some liquids accurately, shows a temperature dependence of the freezing parameters which is similar to Lennard-Jones systems. At very low temperature, the fractional density change on freezing shows a dramatic increase as a function of temperature indicating the importance of all the contributions due to the triplet direction correlation function. Also, we consider the freezing of a one-component liquid into a simple-cubic (sc) lattice by bifurcation analysis and show that this transition is highly unfavorable, independent of interatomic potential choice. The bifurcation diagrams for the three lattices considered are compared and found to be strikingly different. Finally, a new stability analysis of the bifurcation diagrams is presented.

Perturbation expansions and series acceleration procedures: Part-II. Extrapolation techniques

Three new procedures for the extrapolation of series coefficients from a given power series expansion are proposed. They are based on (i) a novel resummation identity, (ii) parametrised Euler transformation (pet) and (iii) a modifiedpet. Several examples taken from the Ising model series expansions, ferrimagnetic systems, etc., are illustrated. Apart from these applications, the higher order virial coefficients for hard spheres and hard discs have also been evaluated using the new techniques and these are compared with the estimates obtained by other methods. A satisfactory agreement is revealed between the two.

Dynamics of dense sheared granular flows. Part 1. Structure and diffusion

Shear flows of inelastic spheres in three dimensions in the Volume fraction range 0.4-0.64 are analysed using event-driven simulations.Particle interactions are considered to be due to instantaneous binary collisions, and the collision model has a normal coefficient of restitution e(n) (negative of the ratio of the post- and pre-collisional relative velocities of the particles along the line joining the centres) and a tangential coefficient of restitution e(t) (negative of the ratio of post- and pre-collisional velocities perpendicular to the line Joining the centres). Here, we have considered both e(t) = +1 and e(t) = e(n) (rough particles) and e(t) =-1 (smooth particles), and the normal coefficient of restitution e(n) was varied in the range 0.6-0.98. Care was taken to avoid inelastic collapse and ensure there are no particle overlaps during the simulation. First, we studied the ordering in the system by examining the icosahedral order parameter Q(6) in three dimensions and the planar order parameter q(6) in the plane perpendicular to the gradient direction. It was found that for shear flows of sufficiently large size, the system Continues to be in the random state, with Q(6) and q(6) close to 0, even for volume fractions between phi = 0.5 and phi = 0.6; in contrast, for a system of elastic particles in the absence of shear, the system orders (crystallizes) at phi = 0.49. This indicates that the shear flow prevents ordering in a system of sufficiently large size. In a shear flow of inelastic particles, the strain rate and the temperature are related through the energy balance equation, and all time scales can be non-dimensionalized by the inverse of the strain rate. Therefore, the dynamics of the system are determined only by the volume fraction and the coefficients of restitution. The variation of the collision frequency with volume fraction and coefficient of estitution was examined. It was found, by plotting the inverse of the collision frequency as a function of volume fraction, that the collision frequency at constant strain rate diverges at a volume fraction phi(ad) (volume fraction for arrested dynamics) which is lower than the random close-packing Volume fraction 0.64 in the absence of shear. The volume fraction phi(ad) decreases as the coefficient of restitution is decreased from e(n) = 1; phi(ad) has a minimum of about 0.585 for coefficient of restitution e(n) in the range 0.6-0.8 for rough particles and is slightly larger for smooth particles. It is found that the dissipation rate and all components of the stress diverge proportional to the collision frequency in the close-packing limit. The qualitative behaviour of the increase in the stress and dissipation rate are well Captured by results derived from kinetic theory, but the quantitative agreement is lacking even if the collision frequency obtained from simulations is used to calculate the pair correlation function used In the theory.

Dynamics of dense sheared granular flows. Part II. The relative velocity distributions

The distribution of relative velocities between colliding particles in shear flows of inelastic spheres is analysed in the Volume fraction range 0.4-0.64. Particle interactions are considered to be due to instantaneous binary collisions, and the collision model has a normal coefficient of restitution e(n) (negative of the ratio of the post- and pre-collisional relative velocities of the particles along the line joining the centres) and a tangential coefficient of restitution e(t) (negative of the ratio of post- and pre-collisional velocities perpendicular to line joining the centres). The distribution or pre-collisional normal relative velocities (along the line Joining the centres of the particles) is Found to be an exponential distribution for particles with low normal coefficient of restitution in the range 0.6-0.7. This is in contrast to the Gaussian distribution for the normal relative velocity in all elastic fluid in the absence of shear. A composite distribution function, which consists of an exponential and a Gaussian component, is proposed to span the range of inelasticities considered here. In the case of roughd particles, the relative velocity tangential to the surfaces at contact is also evaluated, and it is found to be close to a Gaussian distribution even for highly inelastic particles.Empirical relations are formulated for the relative velocity distribution. These are used to calculate the collisional contributions to the pressure, shear stress and the energy dissipation rate in a shear flow. The results of the calculation were round to be in quantitative agreement with simulation results, even for low coefficients of restitution for which the predictions obtained using the Enskog approximation are in error by an order of magnitude. The results are also applied to the flow down an inclined plane, to predict the angle of repose and the variation of the volume fraction with angle of inclination. These results are also found to be in quantitative agreement with previous simulations.

Adsopption isotherms-A critique

The possibility or the impossibility of separating the particle and the electrode interactions is discussed in a wider context of the effects due to any two interaction potentials on the equation of state. The involved nature of the pressure dependence on two individually definable forces is illustrated through the Percus Yevick results for the adhesive hard spheres. An alternative form of the adsorption isotherm is given to bring home the intimate relationship between the actual equation of state and the free energy of adsorption. Thermodynamic consequences of congruence with respect to E (or q) as reflected through the linear plots of q (or E) vs. θ are well known. Mathematical consequences of simultaneous congruence have been pointed out recently. In this paper, the physical nature of congruence hypothesis is revealed. In passing "the pseudo-congruence" is also discussed. It is emphasised that the problem is no less ambiguous with regard to modelling the particle/particle interaction. The ad hoc nature of our dependence of the available equations of state is emphasised through a discussion on the HFL theory. Finally, a heuristic method for modelling ΔG mathematically-incorporating its behaviour at saturation coverages-is advanced. The more interesting aspects of this approach, which generalises almost all isotherms hitherto known, are sketched.

Distortion of Dimension under Quasiconformal Mappings

Quasiconformal mappings are natural generalizations of conformal mappings. They are homeomorphisms with 'bounded distortion' of which there exist several approaches. In this work we study dimension distortion properties of quasiconformal mappings both in the plane and in higher dimensional Euclidean setting. The thesis consists of a summary and three research articles. A basic property of quasiconformal mappings is the local Hölder continuity. It has long been conjectured that this regularity holds at the Sobolev level (Gehring's higher integrabilty conjecture). Optimal regularity would also provide sharp bounds for the distortion of Hausdorff dimension. The higher integrability conjecture was solved in the plane by Astala in 1994 and it is still open in higher dimensions. Thus in the plane we have a precise description how Hausdorff dimension changes under quasiconformal deformations for general sets. The first two articles contribute to two remaining issues in the planar theory. The first one concerns distortion of more special sets, for rectifiable sets we expect improved bounds to hold. The second issue consists of understanding distortion of dimension on a finer level, namely on the level of Hausdorff measures. In the third article we study flatness properties of quasiconformal images of spheres in a quantitative way. These also lead to nontrivial bounds for their Hausdorff dimension even in the n-dimensional case.

Ammatti, ihminen ja maailmankuva murroksessa : Tutkimus yliopistokirjastoista ja kirjastonhoitajista tietoyhteiskuntakaudella 1970-2005

PROFESSION, PERSON AND WORLDVIEW AT A TURNING POINT A Study of University Libraries and Library Staff in the Information Age 1970 - 2005 The incongruity between commonly held ideas of libraries and librarians and the changes that have occurred in libraries since 2000 provided the impulse for this work. The object is to find out if the changes of the last few decades have penetrated to a deeper level, that is, if they have caused changes in the values and world views of library staff and management. The study focuses on Finnish university libraries and the people who work in them. The theoretical framework is provided by the concepts of world view (values, the concept of time, man and self, the experience of the supernatural and the holy, community and leadership). The viewpoint, framework and methods of the study place it in the area of Comparative Religion by applying the world view framework. The time frame is the information age, which has deeply affected Finnish society and scholarly communication from 1970 to 2005. The source material of the study comprises 30 life stories; somewhat more than half of the stories come from the University of Helsinki, and the rest from the other eight universities. Written sources include library journals, planning documents and historical accounts of libraries. The experiences and research diaries of the research worker are also used as source material. The world view questions are discussed on different levels: 1) recognition of the differences and similarities in the values of the library sphere and the university sphere, 2) examination of the world view elements, community and leadership based on the life stories, and 3) the three phases of the effects of information technology on the university libraries and those who work in them. In comparing the values of the library sphere and the university sphere, the appreciation of creative work and culture as well as the founding principles of science and research are jointly held values. The main difference between the values in the university and library spheres concerns competition and service. Competition is part of the university as an institution of research work. The core value of the library sphere is service, which creates the essential ethos of library work. The ethical principles of the library sphere also include the values of democracy and equality as well as the value of intellectual freedom. There is also a difference between an essential value in the university sphere, the value of autonomy and academic freedom on the one hand, and the global value of the library sphere - organizing operations in a practical and efficient way on the other hand. Implementing this value can also create tension between the research community and the library. Based on the life stories, similarities can be found in the values of the library staff members. The value of service seems to be of primary importance for all who are committed to library work and who find it interesting and rewarding. The service role of the library staff can be extended from information services provider to include the roles of teacher, listener and even therapist, all needed in a competitive research community. The values of democracy and equality also emerge fairly strongly. The information age development has progressed in three phases in the libraries from the 1960s onward. In the third phase beginning in the mid 1990s, the increased usage of electronic resources has set fundamental changes in motion. The changes have affected basic values and the concept of time as well as the hierarchies and valuations within the library community. In addition to and as a replacement for the library possessing a local identity and operational model, a networked, global library is emerging. The changes have brought tension both to the library communities and to the relationship between the university community and the library. Future orientation can be said to be the key concept for change; it affects where the ideals and models for operations are taken from. Future orientation manifests itself as changes in metaphors, changes in the model of a good librarian and as communal valuations. Tension between the libraries and research communities can arise if the research community pictures the library primarily as a traditional library building with a local identity, whereas the 21st century library staff and directors are affected by future orientation and membership in a networked library sphere, working proactively to develop their libraries.

The Restless Love of Thinking : The Concept Liebe in Hegel's Philosophy

The German philosopher G.W.F.Hegel (1770–1831) is best known for his idealistic system philosophy, his concept of spirit [Geist] and for his dictum that the existing and the rational overlap. This thesis offers a new perspective: it examines the working of the concept ‘love’ in Hegel’s philosophy by looking at the contexts and function he puts it to, from his earliest writings to the very last lectures he gave. The starting point of the inquiry is that he applied the concept Liebe to different contexts for different purposes, but each time to provide an answer to a specific philosophical problem. His formulation, reformulation and use of ‘love’ give possible solutions to problems the solving of which was crucial to the development of his thought as a whole. The study is divided into three parts, each analysing the different problems and solutions to which Hegel applied the concept of love. The first part, "Love, morality and ethical life", examines these interconnected themes in Hegel’s early work. The main questions he addressed during this period concerned how to unite Kant’s philosophy and the Greek ideal of the good life. In this context, the concept ‘love’ did three things. First, it served to formulate his grounding idea of the relation between unity and difference, or the manifold. Secondly, it was the key to his attempt to base an ideal folk religion on Christianity interpreted as a religion of love. Finally, it provided the means to criticise Kant’s moral philosophy. The question of the moral value of love helped Hegel to break away from Kant’s thought and develop his own theory about love and ethical life. The second part of the study, "Love and the political realm", considers the way 'Liebe' functions in connection with questions concerning the community and political life in Hegel’s work. In addition to questioning the universal applicability of the concept of recognition as a key to his theory of social relations, the chapters focus on gender politics and the way he conceptualised the gender category ‘woman’ through the concept ‘love’. Another line of inquiry is the way the figure of Antigone was used to conceptualise the differentiated spheres of action for men and women, and the part ‘love’ played in Hegel’s description of Antigone’s motives. Thirdly, Hegel’s analogy of the family and the state and the way ‘love’ functions in an attempt to promote understanding of the relation between citizens and the state are examined. The third and final part of the study, "Love as absolute spirit", focuses on ‘love’ within Hegel’s systemic thought and the way he continued to characterise Geist through the language of Liebe up until and including his very last works. It is shown how Liebe functions in his hierarchical organisation of the domains of art, religion and philosophy, and how both art and religion end up in similar structural positions with regard to philosophy. One recurrent theme in the third part is Hegel’s complex relation to Romantic thought. Another line of investigation is how he reconstructed Christianity as a religion of love in his mature work. In striking contrast to his early thought, in his last works Hegel introduced a new concept of love that incorporated negativity, and that could also function as the root of political action.

Post-liquefaction undrained monotonic behaviour of sands: experiments and DEM simulations

This paper presents the results of a series of servo-controlled cyclic triaxial tests and numerical simulations using the three- dimensional discrete element method (DEM) on post-liquefaction undrained monotonic strength of granular materials. In a first test series,undrained monotonic tests were carried out after dissipating the excess pore water pressure developed during liquefaction. The influence of different parameters such as amplitude of axial strain,relative density and confining pressure prior to liquefaction on the post-liquefaction undrained response have been investigated.The results obtained highlight an insignificant influence of amplitude of axial strain, confining pressure and a significant influence of relative density on the post-liquefaction undrained monotonic stress-strain response.In the second series, undrained monotonic tests were carried out on similar triaxial samples without dissipating the excess pore water pressure developed during liquefaction. The results highlight that the amplitude of axial strain prior to liquefaction has a significant influence on the post-liquefaction undrained monotonic response.In addition,DEM simulations have been carried out on an assembly of spheres to simulate post-liquefaction behaviour.The simulations were very similar to the experiments with an objective to understand the behaviour of monotonic strength of liquefied samples from the grain scale. The numerical simulations using DEM have captured qualitatively all the features of the post-liquefaction undrained monotonic response in a manner similar to that of the experiments.In addition,a detailed study on the evolution of micromechanical parameters such as the average coordination number and induced anisotropic coefficients has been reported during the post-liquefaction undrained monotonic loading.

Translink Public Art Installation

This project is a public art work commissioned by Harbinger Consultants and installed at Translink's North Lakes bus station. It comprises 4 reflective stainless steel spheres of various sizes, and 2 screens covering the bus drivers' tea room.

Phenotypic and Functional Characterization of Human Mammary Stem/Progenitor Cells in Long Term Culture

Background: Cancer stem cells exhibit close resemblance to normal stem cells in phenotype as well as function. Hence, studying normal stem cell behavior is important in understanding cancer pathogenesis. It has recently been shown that human breast stem cells can be enriched in suspension cultures as mammospheres. However, little is known about the behavior of these cells in long-term cultures. Since extensive self-renewal potential is the hallmark of stem cells, we undertook a detailed phenotypic and functional characterization of human mammospheres over long-term passages. Methodology: Single cell suspensions derived from human breast `organoids' were seeded in ultra low attachment plates in serum free media. Resulting primary mammospheres after a week (termed T1 mammospheres) were subjected to passaging every 7th day leading to the generation of T2, T3, and T4 mammospheres. Principal Findings: We show that primary mammospheres contain a distinct side-population (SP) that displays a CD24(low)/CD44(low) phenotype, but fails to generate mammospheres. Instead, the mammosphere-initiating potential rests within the CD44(high)/CD24(low) cells, in keeping with the phenotype of breast cancer-initiating cells. In serial sphere formation assays we find that even though primary (T1) mammospheres show telomerase activity and fourth passage T4 spheres contain label-retaining cells, they fail to initiate new mammospheres beyond T5. With increasing passages, mammospheres showed an increase in smaller sized spheres, reduction in proliferation potential and sphere forming efficiency, and increased differentiation towards the myoepithelial lineage. Significantly, staining for senescence-associated beta-galactosidase activity revealed a dramatic increase in the number of senescent cells with passage, which might in part explain the inability to continuously generate mammospheres in culture. Conclusions: Thus, the self-renewal potential of human breast stem cells is exhausted within five in vitro passages of mammospheres, suggesting the need for further improvisation in culture conditions for their long-term maintenance.

Modelling heterogeneity of concrete using 2D lattice network for concrete fracture and comparison with AE study

In this paper, numerical modelling of fracture in concrete using two-dimensional lattice model is presented and also a few issues related to lattice modelling technique applicable to concrete fracture are reviewed. A comparison is made with acoustic emission (AE) events with the number of fractured elements. To implement the heterogeneity of the plain concrete, two methods namely, by generating grain structure of the concrete using Fuller's distribution and the concrete material properties are randomly distributed following Gaussian distribution are used. In the first method, the modelling of the concrete at meso level is carried out following the existing methods available in literature. The shape of the aggregates present in the concrete are assumed as perfect spheres and shape of the same in two-dimensional lattice network is circular. A three-point bend (TPB) specimen is tested in the experiment under crack mouth opening displacement (CMOD) control at a rate of 0.0004 mm/sec and the fracture process in the same TPB specimen is modelled using regular triangular 2D lattice network. Load versus crack mouth opening isplacement (CMOD) plots thus obtained by using both the methods are compared with experimental results. It was observed that the number of fractured elements increases near the peak load and beyond the peak load. That is once the crack starts to propagate. AE hits also increase rapidly beyond the peak load. It is compulsory here to mention that although the lattice modelling of concrete fracture used in this present study is very similar to those already available in literature, the present work brings out certain finer details which are not available explicitly in the earlier works.

VIBRANTe 2.0

ARTIST STATEMENT VIBRANTe 2.0 was inspired by a research project for Parkinson’s disease patients aimed at developing a wearable device to collect relevant data for patients and medical health professionals. Vibrante is a Spanish word that translates to vibrant; literally meaning shaking or vibrations. Vibrante also has a dual meaning including vibrancy, energy, activity, and liveliness. Parkinson’s can be a debilitating disease, but it does not mean the person has to lose energy, activeness or vibrancy. As technology moves from being worn to becoming implantable and completely hidden within the body, the very notion of its physicality becomes difficult to grasp. While the human body hides implantable technology, VIBRANTe 2.0 intentionally hides the human body by making it invisible to reveal the technology stitched within. Wires become veins, delivering lifeblood to the technology inside, allowing it to pulsate and exist, while motherboards become networked hubs by which information is transferred through and within the body, performing functions that mirror and often surpass human performance capabilities. Ultimately, VIBRANTe 2.0 seeks to prompt the viewer to reflect on the potential ramifications of the complete immersion of technology into the human body. CONTEXT Technology is increasingly penetrating all aspects of our environment, and the rapid uptake of devices that live near, on or in our bodies is facilitating radical new ways of working, relating and socialising. Such technology, with its capacity to generate previously unimaginable levels of data, offers the potential to provide life-augmenting levels of interactivity. However, the absorption of technology into the very fabric of clothes, accessories and even bodies begins to dilute boundaries between physical, technological and social spheres, generating genuine ethical and privacy concerns and potentially having implications for human evolution. Embedding technology into the fabric of our clothes, accessories, and even the body enable the acquisition of and the connection to vast amounts of data about people and environments in order to provide life-augmenting levels of interactivity. Wearable sensors for example, offer the potential for significant benefits in the future management of our wellbeing. Fitness trackers such as ‘Fitbit’ and ‘Garmen’ provide wearers with the ability to monitor their personal fitness indicators while other wearables provide healthcare professionals with information that improves diagnosis and observation of medical conditions. This exhibition aimed to illustrate this shifting landscape through a selection of experimental wearable and interactive works by local, national and international artists and designers. The exhibition will also provide a platform for broader debate around wearable technology, our mediated future-selves and human interactions in this future landscape. EXHIBITION As part of Artisan’s Wearnext exhibition, the work was on public display from 25 July to 7 November 2015 and received the following media coverage: [Please refer to Additional URLs]

High lithium storage in micrometre sized mesoporous spherical self-assembly of anatase titania nanospheres and carbon

Composite of anatase titania (TiO2) nanospheres and carbon grown and self-assembled into micron-sized mesoporous spheres via a solvothermal synthesis route are discussed here in the context of rechargeable lithium-ion battery. The morphology and carbon content and hence the electrochemical performance are observed to be significantly influenced by the synthesis parameters. Synthesis conditions resulting in a mesoporous arrangement of an optimized amount carbon and TiO2 exhibited the best lithium battery performance. The first discharge cycle capacity of carbon-titania mesoporous spheres (solvothermal reaction at 150 degrees C at 6 h, calcination at 500 degrees C under air, BET surface area 80 m(2)g(-1)) was 334 mAhg(-1) (approximately 1 Li) at current rate of 0.066 Ag-1. High storage capacity and good cyclability is attributed to the nanostructuring of TiO2 (mesoporosity) as well as due to formation of a percolation network of carbon around the TiO2 nanoparticles. The micron-sized mesoporous spheres of carbon-titania composite nanoparticles also show good rate cyclability in the range (0.066-6.67) Ag-1.

Spherical means with centers on a hyperplane in even dimensions

Given a real-valued function on R-n we study the problem of recovering the function from its spherical means over spheres centered on a hyperplane. An old paper of Bukhgeim and Kardakov derived an inversion formula for the odd n case with great simplicity and economy. We apply their method to derive an inversion formula for the even n case. A feature of our inversion formula, for the even n case, is that it does not require the Fourier transform of the mean values or the use of the Hilbert transform, unlike the previously known inversion formulas for the even n case. Along the way, we extend the isometry identity of Bukhgeim and Kardakov for odd n, for solutions of the wave equation, to the even n case.