Interannual climate variability seen in the Pliocene Model Intercomparison Project

Following reconstructions suggesting weakened temperature gradients along the Equator in the early Pliocene, there has been much speculation about Pliocene climate variability. A major advance for our knowledge about the later Pliocene has been the coordination of modelling efforts through the Pliocene Model Intercomparison Project (PlioMIP). Here the changes in interannual modes of sea surface temperature variability will be presented across PlioMIP. Previously, model ensembles have shown little consensus in the response of the El Niño–Southern Oscillation (ENSO) to imposed forcings – either for the past or future. The PlioMIP ensemble, however, shows surprising agreement, with eight models simulating reduced variability and only one model indicating no change. The Pliocene's robustly weaker ENSO also saw a shift to lower frequencies. Model ensembles focussed on a wide variety of forcing scenarios have not yet shown this level of coherency. Nonetheless, the PlioMIP ensemble does not show a robust response of either ENSO flavour or sea surface temperature variability in the tropical Indian and North Pacific oceans. Existing suggestions linking ENSO properties to to changes in zonal temperature gradient, seasonal cycle and the elevation of the Andes Mountains are investigated, yet prove insufficient to explain the consistent response. The reason for this surprisingly coherent signal warrants further investigation

Mutually Unbiased Bases and Semi-definite Programming

A complex Hilbert space of dimension six supports at least three but not more than seven mutually unbiased bases. Two computer-aided analytical methods to tighten these bounds are reviewed, based on a discretization of parameter space and on Grobner bases. A third algorithmic approach is presented: the non-existence of more than three mutually unbiased bases in composite dimensions can be decided by a global optimization method known as semidefinite programming. The method is used to confirm that the spectral matrix cannot be part of a complete set of seven mutually unbiased bases in dimension six.Comment: 11 pages

An examination of the use of profitability analysis in manufacturing industry

Although profitability analysis has been identified as a useful technique, it is an under-researched area. This paper extends the limited research into profitability analysis by using research interviews to examine the circumstances when profitability analysis is or is not prepared, why various types of profitability analysis are prepared and the how it is used in decision making. Some notable results indicate that operating units prepare profitability analysis when there is an interest in preparing it and the resources exist to prepare it. Operating units prepare both product profitability analysis (PPA) and customer profitability analysis (CPA) to assist with increasing profits through managing low profit or loss making customers. The aim is to identify those products that contribute to the low profit or loss of a customer. In those operating units preparing only PPA, its function is to identify low profit or unprofitable products. This information is used to assist in determining what action should be take to increase the profits of those products. In contrast, customer focused operating units produce only CPA

Non-classicality of temporal correlations

The results of space-like separated measurements are independent of distant measurement settings, a property one might call two-way no-signalling. In contrast, time-like separated measurements are only one-way no-signalling since the past is independent of the future but not vice-versa. For this reason temporal correlations that are formally identical to non-classical spatial correlations can still be modelled classically. We define non-classical temporal correlations as the ones which cannot be simulated by propagating in time a classical information content of a quantum system. We first show that temporal correlations between results of any projective quantum measurements on a qubit can be simulated classically. Then we present a sequence of POVM measurements on a single $m$-level quantum system that cannot be explained by propagating in time $m$-level classical system and using classical computers with unlimited memory.Comment: 6 pages, 1 figur