Lattice Green Functions: the seven-dimensional face-centred cubic lattice

We present a recursive method to generate the expansion of the lattice Green function of the d-dimensional face-centred cubic (fcc) lattice. We produce a long series for d =7. Then we show (and recall) that, in order to obtain the linear differential equation annihilating such a long power series, the most economic way amounts to producing the non-minimal order differential equations. We use the method to obtain the minimal order linear differential equation of the lattice Green function of the seven-dimensional face-centred cubic (fcc) lattice. We give some properties of this irreducible order-eleven differential equation. We show that the differential Galois group of the corresponding operator is included in $SO(11, \mathbb{C})$. This order-eleven operator is non-trivially homomorphic to its adjoint, and we give a "decomposition" of this order-eleven operator in terms of four order-one self-adjoint operators and one order-seven self-adjoint operator. Furthermore, using the Landau conditions on the integral, we forward the regular singularities of the differential equation of the d-dimensional lattice and show that they are all rational numbers. We evaluate the return probability in random walks in the seven-dimensional fcc lattice. We show that the return probability in the d-dimensional fcc lattice decreases as $d^{-2}$ as the dimension d goes to infinity.Comment: 19 page

Les recherches cliniques Nord/Sud : des recherches équitables ?

Section des étudiants / Student's sectionLe but de cet article est de revoir les principaux règlements, scandales et questions posés par les recherches cliniques Nord/Sud à la lumière de 2 principes fondamentaux d’éthique de la recherche : ceux de l’autonomie et de la justice. Aujourd’hui, le débat sur les standards de soins à appliquer dans le cadre des recherches cliniques exportées du Nord vers le Sud, alimente la discussion. Par ailleurs, le paragraphe 30 de la Déclaration d’Helsinki, version 2000, fait l’objet de différentes propositions d’amendement. Il stipule que « tous les patients ayant participé à une étude doivent être assurés de bénéficier à son terme des moyens diagnostiques, thérapeutiques et de prévention dont l’étude aura démontré la supériorité ». Une note explicative y a été ajoutée par l’Association Médicale Mondiale (AMM) en 2004 : les sujets d’étude bénéficieront dans la mesure du possible, des avantages qui en découleraient et qu’ils auraient accès à toute thérapie possible disponible. Pour certains, cela a affaibli le sens de justice que ce paragraphe amenait aux recherches. Plusieurs sont en quête d’un moyen pour établir plus d’équité dans les recherches médicales Nord/Sud. L’un des principes du Commerce équitable est de vendre les produits à un prix plus juste, fixé après dialogue et discussion avec les communautés régionales et locales. Peut-on trouver dans le modèle du commerce équitable des idées applicables aux recherches cliniques Nord/Sud ?The goal of this article is to review the principal regulations, scandals and questions raised by North/South clinical research in the light of 2 fundamental principles of research ethics: Autonomy and Justice. The debate on the standards of care to apply when clinical studies are exported from North to South currently rages. The 30th paragraph of the 2000 Helsinki Declaration is the object of numerous amendment proposals. It stipulates that “at the conclusion of the study, every patient entered into the study should be assured of access to the best proven prophylactic, diagnostic and therapeutic methods identified by the study”. In response to the debate, the World Medical Association (WMA) added an explanatory footnote in 2004, explaining that post trial arrangements must be made for study participants to have access to procedures as beneficial as the study or to other appropriate care. For some, this affected the sense of justice and equity this paragraph had before. Many are trying to think of a good way to organize more fair North/South clinical researches. One of the Fair-trade model principles is to seek equity by paying producers fair prices that have been determined through dialogue and participation of regional or local communities. Can Fair-Trade provide ideas to apply to North/South clinical researches

Conjunction Search Onset Following Single-Feature Preview: Equating Visual Transients

What happens to visual selection if the features of objects in a scene are viewed incrementally rather than simultaneously? According to Olds et al. (2009), it depends upon which feature is presented first. Olds et al. (2009) used the feature-preview search paradigm to cue conjunction search items by presenting observers with a preview display that contained 1 of 2 features for all of the search items. Prior exposure to some features facilitated subsequent visual selection more than prior exposure to others; overall, size-preview offered the greatest search facilitation, followed by color-preview, and lastly, orientation-preview. Some feature-preview conditions, however, contained luminance transients, while others did not. In the present study, we equated relative differences in luminance onsets, across the different feature-preview conditions in order to determine whether or not feature-preview effects are mediated by luminance transients. The general pattern of results obtained by Olds et al. (2009) was replicated and different featurepreviews continued to have differential effects on subsequent search; relative differences in luminance transients did not mediate feature-preview effects. Alternative theories are proposed and discussed

The epistemological beliefs of undergraduates towards Information Science

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonIn the past four decades considerable efforts have been taken by higher education to understand learner’s differences and learning. Learners have different levels of learning ability associated with their different learning motivations, attitudes and thoughts which are built through years of studying at university. The more the researchers understand the learner's differences the better results they will achieve in covering all levels of learning abilities providing the effective learning for learners. The focus of this study is about studying learning thoughts of academic learners which are scientifically called as the epistemological beliefs. Studying the epistemological beliefs from different angles is important to explore its vital role in learning development. The main aim of this study is to investigate the general and specific epistemological beliefs of undergraduates who study information literacy modules as part of information science. The study focuses on the influence of the independent variables (gender, major and academic level) and the interactions between the independent variables and information literacy on undergraduates’ epistemological beliefs. Two questionnaires are used to measure the general and specific epistemological beliefs of the undergraduates; the Schommer Epistemological-Beliefs Questionnaire (SEQ) and the Discipline-Focused Epistemological Belief Questionnaire (DFEBQ). The participants in the study are undergraduates from the College of Education at Kuwait University. SPSS is used to test the internal consistency of the data against the questionnaires. Analysis of variance (ANOVA) is used in order to analyse the data. The study confirms that undergraduates hold both general and specific-domain beliefs while they hold more general beliefs in their first year in the college they develop toward more specific domain beliefs in the fourth year. A final result shows that the undergraduates specific domain beliefs – rather than their general beliefs – are more affected by the variable of previous knowledge of information literacy, as well as a clear impact of the interaction between the independent variables but is not so clear on the general beliefs

Continuous-Variable Quantum Key Distribution

Continuous-Variable Quantum Key Distribution is an alternative to the usual discrete variable quantum key distribution schemes, such as BB84, based on quantum states of light. Optical quantum states are defined in an infinite dimensional Hilbert space hence the "continuous" prefix. Compared to DV-QKD, CVQKD has several advantages such as being compatible with existing telecommunications equipment as one only needs to modulate coherent states of light and perform homodyne/heterodyne detections, but suffers from a lower range, and security proofs are somewhat harder

Engineering a 3D Novel in vitro Perfusion System for Pancreatic Cancer Research

The Pancreatic Ductal Adenocarcinoma is a malignant aggressive disease corresponding to a low survival rate of 5 years, only between 5 to 7%. This is mainly due to the high complexity and density of the malignant tumour microenvironment which difficult the efficiency of potential treatments and furthermore, to the disease’s progression and inhibition of apoptotic pathways. Over the last years, Tissue Engineering has been gaining an even more prominent role regarding the construction of tri-dimensional (3D) in vitro culture systems that enable a better comprehension of the physicochemical properties and a more realistic recapitulation of the structure of tumoural tissues. In this study, it is described for the first time, the use of a perfusion bioreactor for the culture of pancreatic cancer cells in 3D porous polyurethane scaffolds previously coated with one of the most abundant proteins in the extracellular matrix, the fibronectin. This dynamic culture system allowed a higher proliferation of the tumoural cells as well as a greater cell viability when compared to static culture systems. The addition of a chemotherapy agent also showed a higher resistance by the cells cultured in the bioreactor in addition to a lower percentage of cells in apoptosis. The results obtained suggest the great potentiality of perfusion bioreactors in high throughput studies regarding the in vitro culture of cancer cells for the vascularization mimicry of in vivo systems, including drug and treatment screening for patients detected with pancreatic cancer