The chemical potential for the inhomogeneous electron liquid in terms of its kinetic and potential parts with special consideration of the surface pote ntial step and BCS-BEC crossover

The chemical potential $\mu$ of a many-body system is valuable since it carries fingerprints of phase changes. Here, we summarize results for $\mu$ for a thre e-dimensional electron liquid in terms of average kinetic and potential energie s per particle. The difference between $\mu$ and the energy per particle is fou nd to be exactly the electrostatic potential step at the surface. We also prese nt calculations for an integrable one-dimensional many-body system with delta f unction interactions, exhibiting a BCS-BEC crossover. It is shown that in the B CS regime the chemical potential can be expressed solely in terms of the ground -state energy per particle. A brief discussion is also included of the strong c oupling BEC limit.Comment: 4 pages 3 figure

A simple interpretation of quantum mirages

In an interesting new experiment the electronic structure of a magnetic atom adsorbed on the surface of Cu(111), observed by STM, was projected into a remote location on the same surface. The purpose of the present paper is to interpret this experiment with a model Hamiltonian, using ellipses of the size of the experimental ones, containing about 2300 atoms. The charge distribution for the different wavefunctions is analyzed, in particular, for those with energy close to the Fermi energy of copper Ef. Some of them show two symmetric maxima located on the principal axis of the ellipse but not necessarily at the foci. If a Co atom is adsorbed at the site where the wavefunction with energy $E_F$ has a maximum and the interaction is small, the main effect of the adsorbed atom will be to split this particular wavefunction in two. The total charge density will remain the same but the local density of states will present a dip at Ef at any site where the charge density is large enough. We relate the presence of this dip to the observation of quantum mirages. Our interpretation suggests that other sites, apart from the foci of the ellipses, can be used for projecting atomic images and also indicates the conditions for other non magnetic adsorbates to produce mirages.Comment: 3 pages, 3 Fig

Knowledge sharing in project-based supply networks

Purpose: Project-based supply networks are an emerging form of organizing used to meet a buying organization's operational and innovation goals. Knowledge sharing among suppliers in the network plays a key role in successful project delivery but is challenging to achieve in practice. The authors draw on self-determination theory (SDT) to examine the interactive effect of incentive provisions (penalties and bonuses) and network governance (lead or shared) on knowledge sharing motivation by individual boundary-spanners within project-based supply networks. Design/methodology/approach: A scenario-based behavioral experiment of 217 professionals within the UK using the online platform, Prolific, was conducted. A Hayes Macro PROCESS model was used to analyze the data. The authors pilot-tested the scenario with project management experts, senior managers, and directors. Findings: The findings highlighted that the effectiveness of incentive provisions on knowledge sharing may be dependent on the mode of network governance. Where suppliers have shared responsibility for managing the network (shared governance), bonuses were more effective than penalties in motivating knowledge sharing through support of boundary-spanners’ autonomy needs. However, where the buying organization has transferred responsibility for managing the network to an external third-party organization (lead governance), the authors found no significant difference between the effectiveness of penalty versus bonus provisions in motivating knowledge sharing. Originality/value: Prior research in operations and supply chain management (OSCM) has shown the positive effect of incentive provisions on knowledge sharing motivation, but largely overlooked the effectiveness of such incentives when nested within broader governance mechanisms used in projects and their networks. Moreover, while scholars have started to highlight the importance of governance mechanisms in knowledge sharing at the dyadic level, the authors know very little about the impact of network governance

Converging and diverging governance mechanisms:the role of (dys) function in long-term inter-organizational relationships

This paper explores the dynamic interplay of formal/informal governance mechanisms, in terms of functional and dysfunctional consequences for both sides of the dyad, in long-term inter-organizational relationships. Using two longitudinal cases of UK defence sector procurement (warship commissioning) we move beyond notions of complementarity and substitution in governance towards a more nuanced view where the governance mix of inter-organizational relationships can be convergent or divergent. Our findings, showing that relationships can exhibit functional and dysfunctional behaviour simultaneously, lead us to conclude that mismatches in governance mechanisms can be positive as well as negative. In building a context-dependent understanding of governance we both summarize the (dys)functions associated with formal and informal governance mechanisms and explore their impact on relationship exchange performance over time.</p

Cause and Consequences of Genetic and Epigenetic Alterations in Human Cancer

Both genetic and epigenetic changes contribute to development of human cancer. Oncogenomics has primarily focused on understanding the genetic basis of neoplasia, with less emphasis being placed on the role of epigenetics in tumourigenesis. Genomic alterations in cancer vary between the different types and stages, tissues and individuals. Moreover, genomic change ranges from single nucleotide mutations to gross chromosomal aneuploidy; which may or may not be associated with underlying genomic instability. Collectively, genomic alterations result in widespread deregulation of gene expression profiles and the disruption of signalling networks that control proliferation and cellular functions. In addition to changes in DNA and chromosomes, it has become evident that oncogenomic processes can be profoundly influenced by epigenetic mechanisms. DNA methylation is one of the key epigenetic factors involved in regulation of gene expression and genomic stability, and is biologically necessary for the maintenance of many cellular functions. While there has been considerable progress in understanding the impact of genetic and epigenetic mechanisms in tumourigenesis, there has been little consideration of the importance of the interplay between these two processes. In this review we summarize current understanding of the role of genetic and epigenetic alterations in human cancer. In addition we consider the associated interactions of genetic and epigenetic processes in tumour onset and progression. Furthermore, we provide a model of tumourigenesis that addresses the combined impact of both epigenetic and genetic alterations in cancer cells

A Multicenter Study Of Students Sensitivity To Screen-Update Delay

In a climate of shrinking educational budgets, online learning courses offer many advantages; however there are several possible problems associated with electronic learning. There may be problems associated with learning style preferences, student apathy, instructional support, accessibility, and problems with technology. This paper examines a technological problem associated with the effects of screen-update-delay and student enjoyment, student self-reported comprehension, and student objective comprehension. In particular, this paper attempts to identify the point at which longer screen updates will be detrimental to the students enjoyment and/or have a significant negative impact on the students self-reported comprehension and retention of material

Switcher-random-walks: a cognitive-inspired mechanism for network exploration

Semantic memory is the subsystem of human memory that stores knowledge of concepts or meanings, as opposed to life specific experiences. The organization of concepts within semantic memory can be understood as a semantic network, where the concepts (nodes) are associated (linked) to others depending on perceptions, similarities, etc. Lexical access is the complementary part of this system and allows the retrieval of such organized knowledge. While conceptual information is stored under certain underlying organization (and thus gives rise to a specific topology), it is crucial to have an accurate access to any of the information units, e.g. the concepts, for efficiently retrieving semantic information for real-time needings. An example of an information retrieval process occurs in verbal fluency tasks, and it is known to involve two different mechanisms: -clustering-, or generating words within a subcategory, and, when a subcategory is exhausted, -switching- to a new subcategory. We extended this approach to random-walking on a network (clustering) in combination to jumping (switching) to any node with certain probability and derived its analytical expression based on Markov chains. Results show that this dual mechanism contributes to optimize the exploration of different network models in terms of the mean first passage time. Additionally, this cognitive inspired dual mechanism opens a new framework to better understand and evaluate exploration, propagation and transport phenomena in other complex systems where switching-like phenomena are feasible.Comment: 9 pages, 3 figures. Accepted in "International Journal of Bifurcations and Chaos": Special issue on "Modelling and Computation on Complex Networks