A Practitioner’s Approach to Drucker’s Knowledge - Worker Productivity in the 21st Century: A New Model (Part One)

This article examines productivity in the context of the 21st century, focusing on Drucker’s prophecy of knowledge-worker productivity, the power of ‘unified strategy’, organisational interdependence and a practitioner’s approach to knowledge-worker productivity based on Drucker’s six determining factors. From these six factors, a nine building-block based questionnaire survey is developed to establish knowledge-worker productivity readiness status; a knowledge-worker review session to plan towards organisational interdependence and a Drucker-based knowledge-worker productivity implementation framework to manage organisational change. This proposal, intended for business organisations, should also accommodate non-business organisations. Knowledge-worker productivity practice is designed to improve productivity, the quality of work, empowers knowledge workers to accomplish their ‘tasks’ and, consequently, the ‘organisation tasks’ by following an organisational ‘unified strategy’ in an interdependent way that brings about a doing the right thing, the right way approach. This article provides answers to ‘what and how organisations can do to enhance productivity’ from their knowledge-workers, to embrace creativity and develop innovation to provide strategic advantage in sustaining growth in the current new economy of global competition. Team commitment is envisaged through the concept of organisational interdependence. In conclusion, a Drucker-based knowledge-worker productivity implementation framework is proposed, as a management practice to enhance knowledge worker productivity for creativity and commitment. It further demonstrates its competitive power by achieving a unified strategy with implication for organisational change and future applications.knowledge worker; creativity; commitment; productivity; change management; organisational interdependence; unified strategy.

A primal-dual semidefinite programming algorithm tailored to the variational determination of the two-body density matrix

The quantum many-body problem can be rephrased as a variational determination of the two-body reduced density matrix, subject to a set of N-representability constraints. The mathematical problem has the form of a semidefinite program. We adapt a standard primal-dual interior point algorithm in order to exploit the specific structure of the physical problem. In particular the matrix-vector product can be calculated very efficiently. We have applied the proposed algorithm to a pairing-type Hamiltonian and studied the computational aspects of the method. The standard N-representability conditions perform very well for this problem.Comment: 24 pages, 5 figures, submitted to the Journal of Computational Physic

Improved lower bounds for the ground-state energy of many-body systems

New lower bounds for the binding energy of a quantum-mechanical system of interacting particles are presented. The new bounds are expressed in terms of two-particle quantities and improve the conventional bounds of the Hall-Post type. They are constructed by considering not only the energy in the two-particle system, but also the structure of the pair wave function. We apply the formal results to various numerical examples, and show that in some cases dramatic improvement over the existing bounds is reached.Comment: 29 pages, 5 figures, to be published in Phys. Rev.

Correlation effects in single-particle overlap functions and one-nucleon removal reactions

Single-particle overlap functions and spectroscopic factors are calculated on the basis of the one-body density matrices (ODM) obtained for the nucleus $^{16}O$ employing different approaches to account for the effects of correlations. The calculations use the relationship between the overlap functions related to bound states of the (A-1)-particle system and the ODM for the ground state of the A-particle system. The resulting bound-state overlap functions are compared and tested in the description of the experimental data from (p,d) reactions for which the shape of the overlap function is important.Comment: 11 pages, 4 figures include

Solving the Richardson equations for Fermions

Forty years ago Richardson showed that the eigenstates of the pairing Hamiltonian with constant interaction strength can be calculated by solving a set of non-linear coupled equations. However, in the case of Fermions these equations lead to singularities which made them very hard to solve. This letter explains how these singularities can be avoided through a change of variables making the Fermionic pairing problem numerically solvable for arbitrary single particle energies and degeneracies.Comment: 5 pages, 4 figures, submitted to Phys.Rev.

Maximum occupation number for composite boson states

One of the major differences between fermions and bosons is that fermionic states have a maximum occupation number of one, whereas the occupation number for bosonic states is in principle unlimited. For bosons that are made up of fermions, one could ask the question to what extent the Pauli principle for the constituent fermions would limit the boson occupation number. Intuitively one can expect the maximum occupation number to be proportional to the available volume for the bosons divided by the volume occupied by the fermions inside one boson, though a rigorous derivation of this result has not been given before. In this letter we show how the maximum occupation number can be calculated from the ground-state energy of a fermionic generalized pairing problem. A very accurate analytical estimate of this eigenvalue is derived. From that a general expression is obtained for the maximum occupation number of a composite boson state, based solely on the intrinsic fermionic structure of the bosons. The consequences for Bose-Einstein condensates of excitons in semiconductors and ultra cold trapped atoms are discussed.Comment: 4 pages, Revte

Variational determination of the second-order density matrix for the isoelectronic series of beryllium, neon and silicon

The isoelectronic series of Be, Ne and Si are investigated using a variational determination of the second-order density matrix. A semidefinite program was developed that exploits all rotational and spin symmetries in the atomic system. We find that the method is capable of describing the strong static electron correlations due to the incipient degeneracy in the hydrogenic spectrum for increasing central charge. Apart from the ground-state energy various other properties are extracted from the variationally determined second-order density matrix. The ionization energy is constructed using the extended Koopmans' theorem. The natural occupations are also studied, as well as the correlated Hartree-Fock-like single particle energies. The exploitation of symmetry allows to study the basis set dependence and results are presented for correlation-consistent polarized valence double, triple and quadruple zeta basis sets.Comment: 19 pages, 7 figures, 3 tables v2: corrected typo in Eq. (52

Paleoclimatic Reconstruction Based on Molluscan (Gastropoda, Pelecypoda) Environmental Indicators-Late Quaternary of Northwestern Texas

Paleoecologic interpretation of fossil molluscan faunas provides a basis for indirect reconstruction of paleoclimates. Terrestrial and aquatic mollusks are abundant in late Quaternary sedimentary deposits of the western Rolling Plains of Texas. These taxa compose a succession of distinct faunal assemblages. Most mollusks represented in late Pleistocene to middle Holocene assemblages of the region are absent from the modern fauna. However, none of the extirpated species are extinct; their distribution has merely been reduced such that at present, these taxa are found northeast or in montane areas west of the Southern High Plains and Rolling Plains. Because they are living species, their environmental requirements, habitat, and climate are relatively well known. Environments that sustain these mollusks today are presumed to have existed in northwestern Texas in the past. Ecological conditions throughout the Pleistocene and Holocene Epochs can be inferred by tracing the range of environmentally sensitive taxa through radiocarbon-dated stratigraphic sequences. Allowance is made for local variations owing to facies changes and temporary modifications of habitat. Conditions in this region during the late Pleistocene favored diverse molluscan faunas. By comparison, the living fauna is depauperate and virtually restricted to species with broad environmental tolerances; climatic and ecological change was gradual, affecting different species at different times. Regional extirpation of a number of species with comparable ecologic requirements indicates a profound change in environment probably related to climate. Data from three well-constrained stratigraphic sections permit refinement of existing paleoclimatic reconstructions. Climatic variations during the Holocene have taken two related but somewhat independent paths. A summer warming trend that began in the latest Pleistocene greatly increased temperatures by about 8,000 years before present. A similar trend toward desiccation was accelerated between 8,000 and 6,000 years before present until essentially modern conditions were attained 3,000 years before present. Other, comparatively minor fluctuations of the regional paleoclimate are evident as well.Bureau of Economic Geolog

Quasiparticle properties in a density functional framework

We propose a framework to construct the ground-state energy and density matrix of an N-electron system by solving selfconsistently a set of single-particle equations. The method can be viewed as a non-trivial extension of the Kohn-Sham scheme (which is embedded as a special case). It is based on separating the Green's function into a quasi-particle part and a background part, and expressing only the background part as a functional of the density matrix. The calculated single-particle energies and wave functions have a clear physical interpretation as quasiparticle energies and orbitals.Comment: 12 pages, 1 figure, to be published in Phys. Rev.