Environmental impacts of grazed clover/grass pastures

peer-reviwedGrazed clover/grass pastures are important for animal production systems and the clover component is critical for its contribution to N inputs via biological fixation of atmospheric N2. The resource efficiency and environmental emissions for clover/grass pastures can differ from that of N-fertilised grass-only pastures. Fixation of N2 by clover uses photosynthetically- fixed carbon, whereas fertiliser N production consumes fossil fuels and has net greenhouse gas (GHG) emissions. Clover has a higher phosphorus (P) requirement than grass and where extra P fertiliser is used for clover/grass pastures the risk of P loss to waterways is greater than for grass-only pastures. Nitrogen leaching from grazed pasture increases exponentially with increased N inputs and urinary-N contributes 70 to 90% of total N leaching. However, the few studies comparing clover/grass and N-fertilised grass-only pastures at similar total N inputs indicated similar N leaching losses. Nitrous oxide emissions from grazed pastures due to N-cycling of excreta are similar for clover/grass and N-fertilised grass-only pastures at similar total N inputs. However, grass-only pasture requires the application of N fertiliser, which will result in additional specific losses that don’t occur from clover-fixed N. Thus, total N2O emissions are generally higher for N-fertilised grass pastures than for clover/grass pastures. A summary of various whole-system and life cycle assessment analyses for dairy farms from various countries indicated that at similar total N inputs, clover/grass pasture systems can be more efficient than N-fertilised grass systems per kilogram of milk produced from an energy use and GHG perspective whereas results for nutrient losses to waterways were mixed and appear to be similar for both pasture types. In practice, other management practices on farm, such as crop integration, supplementary feeding strategy and winter management, can have a larger overall effect on environmental emissions than whether the N input is derived from fertiliser N or from N2 fixation

Early campaign economic perceptions can help to predict the national verdict on Election Day

It is well known that elections are determined by certain fundamental variables: internal factors that reflect voters’ long-term political predispositions and external factors that are unique to each campaign. Robert S. Erikson and Christopher Wlezien examine how one external factor, the state of the economy, compares to how voters’ internal factors evolve over the final 200 days of presidential campaigns. They find that while noneconomic factors dominate at the outset of the campaign, the economic component increases in salience as Election Day draws nearer and offers greater electoral predictability overall

The Spending Game: Money, Votes, and Incumbency in Congressional Elections

This paper takes a game-theoretic approach to the analysis of the spending-votes relationship in Congressional elections to reinvestigate the surprisingly weak effects of incumbent spending measured in previous studies. Rather than focusing narrowly on the impact of spending on electoral outcomes, we attempt to take account of the reciprocal effect of (anticipated) closeness on spending using several statistical approaches. We also offer improvements in the specification and measurement of the vote equation, by using a better measure of district party strength adjusted for year-effects, and by including a variable that measures the heat of the campaign in terms of total spending by the incumbents and challengers. The latter measure partially corrects for the simultaneously determined (and highly positively correlated) levels of incumbent and challenger spending. A more rigorous multiequation simultaneous equations model, identified by uncorrelated errors, provides even more leverage for sorting out the effects of incumbent and challenger spending on votes. That analysis indicates (in a complete turnaround from findings reported elsewhere) that incumbent spending effects are highly significant and of a magnitude that is, if anything, greater than challenger spending effects. The paper concludes by using a game theoretic model to estimate the effect of anticipated closeness on spending and to estimate differences in campaign financing costs between incumbents and challengers

Equilibria in Campaign Spending Games: Theory and Data

This paper presents a formal game-theoretic model to explain the simultaneity problem that has made it difficult to obtain unbiased estimates of the effects of both incumbent and challenger spending in U.S. House elections. The model predicts a particular form of correlation between the expected closeness of the race and the level of spending by both candidates, which implies that the simultaneity problem should not be present in close races, and should be progressively more severe in range of safe races that are empirically observed. This is confirmed by comparing simple OLS regression of races that are expected to be close with races that are expected not to be close, using House incumbent races spanning two decades. The theory also implies that inclusion of a variable controlling for total spending should successfully produce reliable estimates using OLS. This is confirmed

Forecasting House Seats from General Congressional Polls

According to the frequent polling on the generic ballot for Congress, the Democrats hold a large advantage leading up to the vote on November 7. But does this Democratic edge mean that the Democrats will win a majority of House seats? Doubts are often expressed about the accuracy of the generic ballot polls. And even if the polls are correct in indicating a majority of votes going to Democratic candidates, further doubts are expressed about whether the Democrats' vote margin will be sufficient to win the most seats. This paper is intended to provide some guidance for translating the results of generic congressional polls into the election outcome

National polls and district information point to a 10 seat GOP midterm swing in the House to 244 seats

This midterm cycle, much commentary has been focused on Senate races, given that the Republican Party looks very likely to hold and increase its seats in the House of Representatives. But how many House seats should the GOP expect to win? With a week to go, Joseph Bafumi, Robert S. Erikson, and Christopher Wlezien give an updated House forecast. They write that a combination of the GOP’s incumbency advantage, their domination of state legislatures (and thus, redistricting) since 2010, and U.S. internal migration, mean that the Republican Party are likely to win about 244 seats on November 4th

Structure and dynamics of a model glass: influence of long-range forces

We vary the amplitude of the long-range Coulomb forces within a classical potential describing a model silica glass and study the consequences on the structure and dynamics of the glass, via molecular dynamics simulations. This model allows us to follow the variation of specific features such as the First Sharp Diffraction Peak and the Boson Peak in a system going continuously from a fragile (no Coulomb forces) to a strong (with Coulomb forces) glass. In particular we show that the characteristic features of a strong glass (existence of medium range order, bell-shaped ring size distribution, sharp Boson peak) appear as soon as tetrahedral units are formed.Comment: 5 pages, 4 figures. To be published in J.Phys.: C

A Self-Propelled Biological Process Plk1-Dependent Product-Activated, Feed-Forward Mechanism

Comment on: Park JE, et al. Proc Natl Acad Sci USA 2011; 108:8200-05.Molecular and Cellular Biolog

Forecasting House Seats from General Congressional Polls

According to the frequent polling on the generic ballot for Congress, the Democrats hold a large advantage leading up to the vote on November 7. But does this Democratic edge mean that the Democrats will win a majority of House seats? Doubts are often expressed about the accuracy of the generic ballot polls. And even if the polls are correct in indicating a majority of votes going to Democratic candidates, further doubts are expressed about whether the Democrats' vote margin will be sufficient to win the most seats. This paper is intended to provide some guidance for translating the results of generic congressional polls into the election outcome