The presence of webbing affects the oviposition rate of two-spotted spider mites, Tetranychus urticae (Acari: Tetranychidae)

Several species of tetranychid mites including Tetranychus urticae Koch (Acari: Tetranychidae) construct complicated three-dimensional webs on plant leaves. These webs provide protection against biotic and abiotic stress. As producing web is likely to entail a cost, mites that arrive on a leaf with web are expected to refrain from producing it, because they will gain the benefit of protection from the existing web. Mites that produce less web may then allocate resources that are not spent on web construction to other fitness-enhancing activities, such as laying eggs. To test this, the oviposition rate of T. urticae adult females was examined on leaves with web. As a control, we used leaves where the web had been removed, hence both types of leaves had been exposed to conspecifics previously and were thus damaged. On leaves with web, the oviposition rate of T. urticae females was higher than on leaves where the web had been removed. Therefore, the presence of web constructed by conspecifics enhanced the oviposition rate of T. urticae females. This provides indirect evidence that mites use the web constructed by conspecifics and thereby save resources that can be allocated to other traits that enhance reproductive succes

Political Parties and the Tax Level in the American states: Two Regression Discontinuity Designs

Do parties matter? Yes, but not in the usual way we tend to think of them: big government Democrats and small government Republicans. Our first regression discontinuity design shows that whether the majority in the House of Representatives is Republican or Democratic does not affect the tax level. This surprising result goes against the recent literature in political economy. We then perform another regression discontinuity design in which we find that whether a government is aligned (both the Governor and the majority in the state House belong to the same party) or divided (they belong to different parties) does have an effect on the tax level. Taxes are higher when the government is aligned.Regression discontinuity design, Democrats, Republicans, divided government, line item veto, tax level.

Budgetary Separation of Powers in the American States and the Tax Level: A Regression Discontinuity Design

Should the Federal government and the remaining American states adopt the line item veto? What are its effects? We use regression discontinuity design to claim that in states with the line item veto, divided government has a causal negative effect on the tax level. By investigating a panel of 38 American states from 1960 to 2006, we estimate a significant discontinuous increase of 13% in the tax level as the party affiliated with the Governor in the state Legislature switches from being the minority party to being the majority. In the nine states that have block veto, we find no significant discontinuity in the tax level. We also find little evidence to suggest that the partisan identity of the majority party in the Legislature has a causal effect on the state tax level.Separation of powers, line item veto, tax level, regression discontinuity, nonparametric

Separation of Powers or Ideology? What Determines the Tax Level? Theory and Evidence from the US States.

We find the surprising result that the tax level is negatively correlated with the size of the Democratic majority in the interval in which the Democrats hold between 50 and 66% of the seats in the state Legislatures. This negative relationship suggests the failure of a simple ideological model that had found some support in the literature, that the main determinant of the tax level is the extent of partisan control over the Legislature. We compare this model with an alternative: a separation-of-powers model in which ideology plays no role in determining the tax level. The driving force of our model is the overlap between the supporters of the Governor and the supporters of the legislative majority. The tax level at first rises and then decreases as the size of the ruling majority increases above 50% of the seats, whether the legislative majority is of the same party as the Governor or from the opposition. This non-monotonic relationship is observed in the data and explained by our model.Separation of powers, divided government, line-item veto, tax level, semiparametric.

Inversion of spinning sound fields

A method is presented for the reconstruction of rotating monopole source distributions using acoustic pressures measured on a sideline parallel to the source axis. The method requires no \textit{a priori} assumptions about the source other than that its strength at the frequency of interest vary sinusoidally in azimuth on the source disc so that the radiated acoustic field is composed of a single circumferential mode. When multiple azimuthal modes are present, the acoustic field can be decomposed into azimuthal modes and the method applied to each mode in sequence. The method proceeds in two stages, first finding an intermediate line source derived from the source distribution and then inverting this line source to find the radial variation of source strength. A far-field form of the radiation integrals is derived, showing that the far field pressure is a band-limited Fourier transform of the line source, establishing a limit on the quality of source reconstruction which can be achieved using far-field measurements. The method is applied to simulated data representing wind-tunnel testing of a ducted rotor system (tip Mach number~0.74) and to control of noise from an automotive cooling fan (tip Mach number~0.14), studies which have appeared in the literature of source identification.Comment: Revised version of paper submitted to JASA; five more figures; expanded content with more discussion of error behaviour and relation to Nearfield Acoustical Holograph