Control of corn diseases in Illinois

"In cooperation with Office of Cereal Crops and Diseases, Bureau of Plant Industry, U.S. Department of Agriculture.

Well-posedness for the diffusive 3D Burgers equations with initial data in H1/2H^{1/2}

In this note we discuss the diffusive, vector-valued Burgers equations in a three-dimensional domain with periodic boundary conditions. We prove that given initial data in $H^{1/2}$ these equations admit a unique global solution that becomes classical immediately after the initial time. To prove local existence, we follow as closely as possible an argument giving local existence for the Navier--Stokes equations. The existence of global classical solutions is then a consequence of the maximum principle for the Burgers equations due to Kiselev and Ladyzhenskaya (1957). In several places we encounter difficulties that are not present in the corresponding analysis of the Navier--Stokes equations. These are essentially due to the absence of any of the cancellations afforded by incompressibility, and the lack of conservation of mass. Indeed, standard means of obtaining estimates in $L^2$ fail and we are forced to start with more regular data. Furthermore, we must control the total momentum and carefully check how it impacts on various standard estimates.Comment: 15 pages, to appear in "Recent Progress in the Theory of the Euler and Navier--Stokes Equations", eds. J.C. Robinson, J.L. Rodrigo, W. Sadowski and A. Vidal-L\'opez, Cambridge University Press, 201

'Descended from immigrants and revolutionists': how family immigration history shapes representation in Congress

Does recent immigrant lineage influence the legislative behavior of members of Congress on immigration policy? We examine the relationship between the immigrant background of legislators (i.e., their generational distance from immigration) and legislative behavior, focusing on roll-call votes for landmark immigration legislation and congressional speech on the floor. Legislators more proximate to the immigrant experience tend to support more permissive immigration legislation. Legislators with recent immigration backgrounds also speak more often about immigration in Congress, though the size of immigrant constituencies in their districts accounts for a larger share of this effect. A regression discontinuity design on close elections, which addresses selection bias concerns and holds district composition constant, confirms that legislators with recent immigrant backgrounds tend to support pro-immigration legislation. Finally, we demonstrate how a common immigrant identity can break down along narrower ethnic lines in cases where restrictive legislation targets specific places of origin. Our findings illustrate the important role of immigrant identity in legislative behavior and help illuminate the legislative dynamics of present-day immigration policy.Accepted manuscrip

The Emperor Has No Clothes: Confronting the DC Circuit’s Usurpation of SEC Rulemaking Authority

In The Emperor Has No Clothes: Confronting the D.C. Circuit’s Usurpation of SEC Rulemaking Authority, Professor James D. Cox of Duke University School of Law & Benjamin J.C. Baucom, recent law clerk to Justice Don R. Willett of the Supreme Court of Texas, argue “that the level of review invoked by the D.C. Circuit in Business Roundtable and its earlier decisions is dramatically inconsistent with the standard enacted by Congress.” They conclude “that the D.C. Circuit has assumed for itself a role opposed to the one Congress prescribed for courts reviewing SEC rules.

Supersymmetry and the AdS Higgs Phenomenon

We examine the AdS Higgs phenomenon for spin-1 fields, and demonstrate that graviphotons pick up a dynamically generated mass in AdS_4, once matter boundary conditions are relaxed. We perform an explicit one-loop calculation of the graviphoton mass, and compare this result with the mass generated for the graviton in AdS. In this manner, we obtain a condition for unbroken supersymmetry. With this condition, we examine both N=2 and N=4 gauged supergravities coupled to matter multiplets, and find that for both cases the ratio between dynamically generated graviton and graviphoton masses is consistent with unbroken supersymmetry.Comment: 12 pages, JHEP forma

A Sufficient Condition for Nilpotency in a Finite Group

It is shown that finite groups in which the order of the product of every pair of elements of co-prime order is the product of the orders, is nilpotent

The highly conserved Escherichia coli transcription factor YhaJ regulates aromatic compound degradation

The aromatic compound 2,4-dinitrotoluene (DNT), a common impurity in 2,4,6-trinitrotoluene (TNT) production, has been suggested as a tracer for the presence of TNT-based landmines due to its stability and high volatility. We have previously described an Escherichia coli bioreporter capable of detecting the presence of DNT vapors, harboring a fusion of the yqjF gene promoter to a reporter element. However, the DNT metabolite which is the direct inducer of yqjF, has not yet been identified, nor has the regulatory mechanism of the induction been clarified. We demonstrate here that the YhaJ protein, a member of the LysR type family, acts as a transcriptional regulator of yqjF activation, as well as of a panel of additional E. coli genes. This group of genes share a common sequence motif in their promoters, which is suggested here as a putative YhaJ-box. In addition, we have linked YhaJ to the regulation of quinol-like compound degradation in the cell, and identified yhaK as playing a role in the degradation of DNT

Odors: from chemical structures to gaseous plumes

We are immersed within an odorous sea of chemical currents that we parse into individual odors with complex structures. Odors have been posited as determined by the structural relation between the molecules that compose the chemical compounds and their interactions with the receptor site. But, naturally occurring smells are parsed from gaseous odor plumes. To give a comprehensive account of the nature of odors the chemosciences must account for these large distributed entities as well. We offer a focused review of what is known about the perception of odor plumes for olfactory navigation and tracking, which we then connect to what is known about the role odorants play as properties of the plume in determining odor identity with respect to odor quality. We end by motivating our central claim that more research needs to be conducted on the role that odorants play within the odor plume in determining odor identity