Effect of organic crop rotations on long-term development of the weed seedbank

Changes in the weed seedbank were monitored between 1991 and 1998 in two experiments that were established to compare organic crop rotations at two sites in NE Scotland. Two rotations, replicated twice at each site, were compared and all courses of both rotations were present every year. There were relatively minor changes in weed species diversity over time, but major changes in seedbank abundance. Weed seed numbers were relatively low in rotations with a high proportion of grass/clover ley. Differences in level of seedbank across the rotation were relatively predictable at Tulloch but much less so at Woodside where factors such as the effect of the grass/clover ley seemed to play a lesser role. Other factors, such as weather and its influence on the effectiveness of weed control operations, and higher populations of ground-living arthropods, may be affecting the Woodside seedbanks

Monotonicity Anomalies in Scottish Local Government Elections

The single transferable vote (STV) voting method is used to elect multiple candidates in ranked-choice elections. One weakness of STV is that it fails multiple fairness criteria related to monotonicity and no-show paradoxes. We analyze 1,079 local government STV elections in Scotland to estimate the frequency of such monotonicity anomalies in real-world elections, and compare our results with prior empirical and theoretical research about the rates at which such anomalies occur. In 41 of the 1079 elections we found some kind of monotonicity anomaly. We generally find that the rates of anomalies are similar to prior empirical research and much lower than what most theoretical research has found. Most of the STV anomalies we find are the first of their kind to be documented in real-world elections.Comment: 30 page

A Mathematical Analysis of the 2022 Alaska Special Election for US House

The August 2022 Alaska Special Election for US House contained many interesting features from the perspective of social choice theory. This election used instant runoff voting (often referred to as ranked choice voting) to elect a winner, and many of the weaknesses of this voting method were on display in this election. For example, the Condorcet winner is different from the instant runoff winner, and the election demonstrated a monotonicity paradox. The election also demonstrated a no show paradox; as far as we are aware, this election represents the first document American ranked choice election to demonstrate this paradox

Paradoxical Oddities in Two Multiwinner Elections from Scotland

Ranked-choice voting anomalies such as monotonicity paradoxes have been extensively studied through creating hypothetical examples and generating elections under various models of voter behavior. However, very few real-world examples of such voting paradoxes have been found and analyzed. We investigate two single-transferable vote elections from Scotland that demonstrate upward monotonicity, downward monotonicity, no-show, and committee size paradoxes. These paradoxes are rarely observed in real-world elections, and this article is the first case study of such paradoxes in multiwinner elections

African trypanosomiasis in travelers returning to the United Kingdom.

Two returning safari tourists with African trypanosomiasis were admitted to the Hospital for Tropical Diseases, London, in a 3-day period, compared with six cases in the previous 14 years. We describe the clinical features, diagnosis, and problems encountered in accessing appropriate therapy, and discuss the potential for emergence of this disease in increasingly adventurous international travelers

Eigenvalue assignments and the two largest multiplicities in a Hermitian matrix whose graph is a tree

Among the possible multiplicity lists for the eigenvalues of Hermitian matrices whose graph is a tree we focus upon M(2), the maximum value of the sum of the two largest multiplicities. The corresponding M(1) is already understood. The notion of assignment (of eigenvalues to subtrees) is formalized and applied. Using these ideas, simple upper and lower bounds are given for M(2) (in terms of simple graph theoretic parameters), cases of equality are indicated, and a combinatorial algorithm is given to compute M(2) precisely. In the process, several techniques are developed that likely have more general uses. (C) 2009 Elsevier B.V. All rights reserved