An ignition key for atomic-scale engines

A current-carrying resonant nanoscale device, simulated by non-adiabatic molecular dynamics, exhibits sharp activation of non-conservative current-induced forces with bias. The result, above the critical bias, is generalized rotational atomic motion with a large gain in kinetic energy. The activation exploits sharp features in the electronic structure, and constitutes, in effect, an ignition key for atomic-scale motors. A controlling factor for the effect is the non-equilibrium dynamical response matrix for small-amplitude atomic motion under current. This matrix can be found from the steady-state electronic structure by a simpler static calculation, providing a way to detect the likely appearance, or otherwise, of non-conservative dynamics, in advance of real-time modelling.

The Bright Side of Manufacturing–Remanufacturing Conflict in a Decentralised Closed-Loop Supply Chain

Researchers and managers broadly agree that original equipment manufacturers (OEMs), which have opportunities to produce both new and remanufactured products, are better off by centrally controlling their manufacturing and remanufacturing activities. Thus, OEMs should not remanufacture used products until the remanufacturing cost is sufficiently low to overcome the negative impact of new product cannibalisation. In this paper, we present a contrasting view of the manufacturing–remanufacturing conflict: OEMs sometimes benefit from the decentralised control mode under which they ignore the internal cannibalisation rather than the remanufacturing option. We consider a decentralised closed-loop supply chain in which one OEM can purchase new components from one supplier to produce new products and collect used products from consumers to produce remanufactured products. The key feature of our model is that the OEM can select a centralised or decentralised control mode to manage its manufacturing and remanufacturing activities before the supplier prices the new component. In a steady state period setting, we analyse the players’ optimal decisions and compare the OEM's profits under centralised and decentralised control modes. Our analytic results reveal that the decentralised control within the OEM can outperform the centralised control when the cost structure of producing new and remanufactured products satisfies certain conditions. Finally, the key findings are distilled in a conceptual framework and its managerial implications are discussed.

A complete analytic theory for structure and dynamics of populations and communities spanning wide ranges in body size

The prediction and management of ecosystem responses to global environmental change would profit from a clearer understanding of the mechanisms determining the structure and dynamics of ecological communities. The analytic theory presented here develops a causally closed picture for the mechanisms controlling community and population size structure, in particular community size spectra, and their dynamic responses to perturbations, with emphasis on marine ecosystems. Important implications are summarised in non-technical form. These include the identification of three different responses of community size spectra to size-specific pressures (of which one is the classical trophic cascade), an explanation for the observed slow recovery of fish communities from exploitation, and clarification of the mechanism controlling predation mortality rates. The theory builds on a community model that describes trophic interactions among size-structured populations and explicitly represents the full life cycles of species. An approximate time-dependent analytic solution of the model is obtained by coarse graining over maturation body sizes to obtain a simple description of the model steady state, linearising near the steady state, and then eliminating intraspecific size structure by means of the quasi-neutral approximation. The result is a convolution equation for trophic interactions among species of different maturation body sizes, which is solved analytically using a novel technique based on a multiscale expansion.

High-performance FPGA implementation of DES using a novel method for implementing the key schedule

A generic, parameterisable key scheduling core is presented, which can be utilised in pipelinable private-key encryption algorithms. The data encryption standard (DES) algorithm, which lends itself readily to pipelining, is utilised to exemplify this novel key scheduling method and the broader applicability of the method to other encryption algorithms is illustrated. The DES design is implemented on Xilinx Virtex FPGA technology. Utilising the novel method, a 16-stage pipelined DES design is achieved, which can run at an encryption rate of 3.87 Gbit/s. This result is among the fastest hardware implementations and is a factor 28 times faster than software implementations.

The Evil Key

A new original poem

The social construction of illness:Key insights and policy implications.

The social construction of illness is a major research perspective in medical sociology. This article traces the roots of this perspective and presents three overarching constructionist findings. First, some illnesses are particularly embedded with cultural meaning--which is not directly derived from the nature of the condition--that shapes how society responds to those afflicted and influences the experience of that illness. Second, all illnesses are socially constructed at the experiential level, based on how individuals come to understand and live with their illness. Third, medical knowledge about illness and disease is not necessarily given by nature but is constructed and developed by claims-makers and interested parties. We address central policy implications of each of these findings and discuss fruitful directions for policy-relevant research in a social constructionist tradition. Social constructionism provides an important counterpoint to medicine's largely deterministic approaches to disease and illness, and it can help us broaden policy deliberations and decisions.

A revised age for the Kawakawa/Oruanui tephra, a key marker for the Last Glacial Maximum in New Zealand

The Kawakawa/Oruanui tephra (KOT) is a key chronostratigraphic marker in terrestrial and marine deposits of the New Zealand (NZ) sector of the southwest Pacific. Erupted early during the Last Glacial Maximum (LGM), the wide distribution of the KOT enables inter-regional alignment of proxy records and facilitates comparison between NZ climatic variations and those from well-dated records elsewhere. We present 22 new radiocarbon ages for the KOT from sites and materials considered optimal for dating, and apply Bayesian statistical methods via OxCal4.1.7 that incorporate stratigraphic information to develop a new age probability model for KOT. The revised calibrated age, ±2 standard deviations, for the eruption of the KOT is 25,360 ± 160 cal yr BP. The age revision provides a basis for refining marine reservoir ages for the LGM in the southwest Pacific.