Assessing Dynamic Efficiency: Theory and Evidence

The issue of dynamic efficiency is central to analyses of capital accumulation and economic growth. Yet the question of what operating characteristics of an economy subject to productivity shocks should be examined to determine whether or not it is efficient has not been resolved. This paper develops criterion based on observables for determining whether or not an economy is dynamically efficient. The criterion involves a comparison of the cash flows generated by capital with the volume of investment. Its application to the United States economy and the economies of other major OECD nations suggests that they are dynamically efficient.

Use of aerial thermography in Canadian energy conservation programs

Recent developments in the use of aerial thermography in energy conservation programs within Canada were summarized. Following a brief review of studies conducted during the last three years, methodologies of data acquisition, processing, analysis and interpretation was discussed. Examples of results from an industrial oriented project were presented and recommendations for future basic work were outlined

Size-Dependent Optical and Electrochemical Energy Gaps Comparison of CdSe Nanolusters

poster abstractThe size-dependent optical and electronic properties of semiconductor nanocrystals have made them the focus of much research including the designing of photovoltaic devices and photocatalysts. These properties occur as a result of the phenomenon called quantum confinement. To improve the device efficiency it is important to have a better understanding of their size dependent electrochemical properties. Herein we demonstrate for the first time, a comparison of the size dependent optical properties and electrochemical energy gaps of poly(ethylene glycol) thiolate-protected ultra-small CdSe nanoclusters. The electrochemical energy gaps for various sized nanoclusters were determined from cyclic and differential pulse voltammetry in organic solvent/electrolyte medium, where large, moleculelike HOMO-LUMO energy gaps were observed. It was also found that a significant amount of charging energy is involved in the electrochemical energy gap. The effect of the thickness of the surface-pasivating ligands on the HOMO-LUMO energy gap is demonstrated and a quantized double layer (QDL) charging model presented

Analysis of millimetre-wave polarization diverse multiple-input multiple-output capacity

Millimetre-waves offer the possibility of wide bandwidth and consequently high data rate for wireless communications. For both uni- and dual-polarized systems, signals sent over a link may suffer severe degradation due to antenna misalignment. Orientation robustness may be enhanced by the use of mutual orthogonality in three dimensions. Multiple-input multiple-output polarization diversity offers a way of improving signal reception without the limitations associated with spatial diversity. Scattering effects often assist propagation through multipath. However, high path loss at millimetre-wave frequencies may limit any reception enhancement through scattering. We show that the inclusion of a third orthogonal dipole provides orientation robustness in this setting, as well as in a rich scattering environment, by means of a Rician fading channel model covering all orientations for a millimetre-wave, tri-orthogonal, half-wave dipole transmitter and receiver employing polarization diversity. Our simulation extends the analysis into three dimensions, fully exploiting individual sub-channel paths. In both the presence and absence of multipath effects, capacity is observed to be higher than that of a dual-polarized system over the majority of a field of view.Nicholas P. Lawrence, Brian W.-H.Ng, Hedley J. Hansen, and Derek Abbot

Climatically driven loss of calcium in steppe soil as a sink for atmospheric carbon

During the last several thousand years the semi‐arid, cold climate of the Russian steppe formed highly fertile soils rich in organic carbon and calcium (classified as Chernozems in the Russian system). Analysis of archived soil samples collected in Kemannaya Steppe Preserve in 1920, 1947, 1970, and fresh samples collected in 1998 indicated that the native steppe Chernozems, however, lost 17–28 kg m−2 of calcium in the form of carbonates in 1970–1998. Here we demonstrate that the loss of calcium was caused by fundamental shift in the steppe hydrologic balance. Previously unleached soils where precipitation was less than potential evapotranspiration are now being leached due to increased precipitation and, possibly, due to decreased actual evapotranspiration. Because this region receives low levels of acidic deposition, the dissolution of carbonates involves the consumption of atmospheric CO2. Our estimates indicate that this climatically driven terrestrial sink of atmospheric CO2 is ∼2.1–7.4 g C m−2 a−1. In addition to the net sink of atmospheric carbon, leaching of pedogenic carbonates significantly amplified seasonal amplitude of CO2 exchange between atmosphere and steppe soil

Revising the role of the history of mathematics in post-pandemic world

In this short philosophical and discursive paper, the main objective is to reassess a new emergent role of the history of mathematics in order to bring about greater diversity and engagement in the mathematical sciences. The discussion is based around the project undertaken at a North London university and their partner pre-university college, which piloted the larger national project in the UK in the local context. The success of the project, it is further suggested, would greatly benefit from a framework in which the history of mathematics as a humanistic discipline is closely related to viewing mathematics as a virtuous practice. We also include a short summary about the lives and careers of two Serbian mathematicians, Judita Cofman, and Milica Ilić-Dajović, to showcase how learning about the ways in which marginalisation takes place can help students position themselves and contextualise their priorities as they enter the professional mathematics landscape

Searching for Dark Matter at the LHC with a Mono-Z

We investigate a mono-Z process as a potential dark matter search strategy at the LHC. In this channel a single Z boson recoils against missing transverse momentum, attributed to dark matter particles, $\chi$, which escape the detector. This search strategy is related, and complementary to, monojet and monophoton searches. For illustrative purposes we consider the process $q\bar{q} -> \chi\chi Z$ in a toy dark matter model, where the Z boson is emitted from either the initial state quarks, or from the internal propagator. Among the signatures of this process will be a pair of muons with high pT that reconstruct to the invariant mass of the Z, and large amounts of missing transverse energy. Being a purely electroweak signal, QCD and other Standard Model backgrounds are relatively easily removed with modest selection cuts. We compare the signal to Standard Model backgrounds and demonstrate that, even for conservative cuts, there exist regions of parameter space where the signal may be clearly visible above background in future LHC data, allowing either new discovery potential or the possibility of supplementing information about the dark sector beyond that available from other observable channels.Comment: 11 pages, 13 figure

Computational inference in systems biology

Parameter inference in mathematical models of biological pathways, expressed as coupled ordinary differential equations (ODEs), is a challenging problem. The computational costs associated with repeatedly solving the ODEs are often high. Aimed at reducing this cost, new concepts using gradient matching have been proposed. This paper combines current adaptive gradient matching approaches, using Gaussian processes, with a parallel tempering scheme, and conducts a comparative evaluation with current methods used for parameter inference in ODEs

Two energy scales and slow crossover in YbAl3

Experimental results for the susceptibility, specific heat, 4f occupation number, Hall effect and magnetoresistance for single crystals of YbAl$_{3}$ show that, in addition to the Kondo energy scale $k_{B}T_{K}$ $$ 670K, there is a low temperature scale $T_{coh}<50$K for the onset of coherence. Furthermore the crossover from the low temperature Fermi liquid regime to the high temperature local moment regime is slower than predicted by the Anderson impurity model. These effects may reflect the behavior of the Anderson Lattice in the limit of low conduction electron density.Comment: Ten pages, including three figure