Efficiency of surface-driven motion: nano-swimmers beat micro-swimmers

Surface interactions provide a class of mechanisms which can be employed for propulsion of micro- and nanometer sized particles. We investigate the related efficiency of externally and self-propelled swimmers. A general scaling relation is derived showing that only swimmers whose size is comparable to, or smaller than, the interaction range can have appreciable efficiency. An upper bound for efficiency at maximum power is 1/2. Numerical calculations for the case of diffusiophoresis are found to be in good agreement with analytical expressions for the efficiency

Horizontal Equity and Progession when Equivalence Scales are not Constant.

Household needs must be taken into account when designing an equitable income tax. If the equivalence scale is income dependent it is not transparent how to achieve equity. In this paper we explore the question of horizontal equity and the implications for progression (vertical equity), when the equivalence scale depends on income level. In particular an 'equal progression among equals' criterion is articulated and shown to be achievable along with horizontal equity under specified conditions.

Efficiency of autonomous soft nano-machines at maximum power

We consider nano-sized artificial or biological machines working in steady state enforced by imposing non-equilibrium concentrations of solutes or by applying external forces, torques or electric fields. For unicyclic and strongly coupled multicyclic machines, efficiency at maximum power is not bounded by the linear response value 1/2. For strong driving, it can even approach the thermodynamic limit 1. Quite generally, such machines fall in three different classes characterized, respectively, as "strong and efficient", "strong and inefficient", and "balanced". For weakly coupled multicyclic machines, efficiency at maximum power has lost any universality even in the linear response regime

Orthogonal nets and Clifford algebras

A Clifford algebra model for M"obius geometry is presented. The notion of Ribaucour pairs of orthogonal systems in arbitrary dimensions is introduced, and the structure equations for adapted frames are derived. These equations are discretized and the geometry of the occuring discrete nets and sphere congruences is discussed in a conformal setting. This way, the notions of ``discrete Ribaucour congruences'' and ``discrete Ribaucour pairs of orthogonal systems'' are obtained --- the latter as a generalization of discrete orthogonal systems in Euclidean space. The relation of a Cauchy problem for discrete orthogonal nets and a permutability theorem for the Ribaucour transformation of smooth orthogonal systems is discussed.Comment: Plain TeX, 16 pages, 4 picture

Environmental governance in China

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Library Cooperation as a Precursor to Enhanced Library Services Provision in Academic Libraries in Imo State.

Purpose: The study investigated library cooperation and provision of library services in academic libraries in Imo State.Design/Methodology/Approach: Survey design was adopted in carrying out this study. The 180 professional and para-professional staff in the six (6) tertiary institutions’ libraries which include Imo State University library, Federal Polytechnic Nekede, Alvan Ikoku Federal College of Education, Imo Polytechnic, Federal College of Land Resources and Technology and Federal University of Technology, Owerri. Total enumeration sampling procedure was employed to take complete count of the population.Findings: Findings of the study revealed that interlibrary loan, exchange and joint publication constitute the few areas of library cooperation in the tertiary institutions studied; and there is significant relationship between library cooperation and provision of library services in the tertiary institutions studied whereas inadequate funding, outdated technology and fear of loss of resources are some of the challenges posed by library cooperation.Originality/Value: The study provides empirical justification for the effectiveness of library cooperation on quality service delivery