The vector innovation structural time series framework: a simple approach to multivariate forecasting

The vector innovation structural time series framework is proposed as a way of modelling a set of related time series. Like all multi-series approaches, the aim is to exploit potential inter-series dependencies to improve the fit and forecasts. A key feature of the framework is that the series are decomposed into common components such as trend and seasonal effects. Equations that describe the evolution of these components through time are used as the sole way of representing the inter-temporal dependencies. The approach is illustrated on a bivariate data set comprising Australian exchange rates of the UK pound and US dollar. Its forecasting capacity is compared to other common single- and multi-series approaches in an experiment using time series from a large macroeconomic database.Vector innovation structural time series, state space model, multivariate time series, exponential smoothing, forecast comparison, vector autoregression.

Why Is There So Little Money in Politics?

In this paper, we argue that campaign contributions are not a form of policy-buying, but are rather a form of political participation and consumption. We summarize the data on campaign spending, and show through our descriptive statistics and our econometric analysis that individuals, not special interests, are the main source of campaign contributions. Moreover, we demonstrate that campaign giving is a normal good, dependent upon income, and campaign contributions as a percent of GDP have not risen appreciably in over 100 years: if anything, they have probably fallen. We then show that only one in four studies from the previous literature support the popular notion that contributions buy legislators' votes. Finally, we illustrate that when one controls for unobserved constituent and legislator effects, there is little relationship between money and legislator votes. Thus, the question is not why there is so little money politics, but rather why organized interests give at all. We conclude by offering potential answers to this question.

Predicted Electronic and Thermodynamic Properties of a Newly Discovered Zn_8Sb_7 Phase

A new binary compound, Zn_8Sb_7, has recently been prepared in nanoparticulate form via solution synthesis. No such phase is known in the bulk phase diagram; instead, one would expect phase separation to the good thermoelectric semiconductors ZnSb and Zn_4Sb_3. Here, density functional calculations are employed to determine the free energies of formation, including effects from vibrations and configurational disorder, of the relevant phases, yielding insight into the phase stability of Zn_8Sb_7. Band structure calculations predict Zn_8Sb_7, much like ZnSb and Zn_4Sb_3, to be an intermetallic semiconductor with similar thermoelectric properties. If sufficient entropy or surface energy exists to stabilize the bulk material, it would be stable in a limited temperature window at high temperature

Tensor extension of the Poincar\'e algebra

A tensor extension of the Poincar\'e algebra is proposed for the arbitrary dimensions. Casimir operators of the extension are constructed. A possible supersymmetric generalization of this extension is also found in the dimensions $D=2,3,4$.Comment: 1+7 pages, LaTe

Apple orchard frost protection with wind machine operation

Research has shown that wind machines are more effective under conditions of strong thermal inversions. Quantitative relationships between the level of protection and inversion strength, however, are not well known, and there are few reports on the effect of fan operation on energy balance. Whether the wind machines should be started before surface cooling causes turbulence damping and atmospheric stratification or if it is possible to delay starting until just before the critical temperature occurs remains a matter of discussion. Therefore, experiments were conducted on 11 spring frost nights during the 1999 and 2000 to assess the effectiveness of a fan operation on frost protection of an apple orchard under different microclimatic conditions. The 11 frost events were characterized by light winds (0.58–1.92 m s−1) and clear skies for most of the night, resulting in an average accumulated radiative loss of 2.67 ± 0.38 MJ m−2. The air temperature increased immediately after the wind machines were started and the temperature rise depended on inversion strength. For each 1 °C increase in temperature inversion strength between 1.5 and 15 m height, wind machine operation caused a 0.3 °C increase of air temperature at a 1.5 m height within the main area affected by the fan operation. Using multiple regression, the area protected was significantly related to the temperature increase and the inversion strength. Wind machine operation reduced flower damage by 60% in 1999 and 37% in 2000. Distribution of flower damage varied spatially, and it was related to wind drift