The Jets of AGN as giant co-axial cables

The currents carried by the jets of active galactic nuclei (AGNs) can be probed using maps of the Faraday rotation measure (RM), since a jet current will be accompanied by a toroidal magnetic (B) field, which will give rise to a systematic change in the RM across the jet. The aim of this study is to identify new AGNs displaying statistically significant transverse RM gradients across their parsec-scale jets, and to look for overall patterns in the implied directions for the toroidal B-field components and jet currents. We have carried out new analyses of Faraday RM maps derived from previously published 8.1, 8.4, 12.1 and 15.3 GHz data obtained in 2006 on the NRAO VLBA. In a number of important ways, our procedures were identical to those of the original authors, but several other key aspects of the new imaging and analysis differ from the original methods. Our new analysis has substantially increased the number of AGNs known to display transverse RM gradients. The collected data on parsec and kiloparsec scales indicate that the current typically flows inward along the jet axis and outward in a more extended region surrounding the jet, typical to the current structure of a coaxial cable, accompanied by a self-consistent system of nested helical B fields, whose toroidal components give rise to the observed transverse RM gradients. These new results make it possible for the first time to conclusively demonstrate the existence of a preferred direction for the toroidal B-field components - and therefore of the currents - of AGN jets. Discerning the origin of this current-field system is of cardinal importance for understanding the physical mechanisms leading to the formation of the intrinsic jet B field, which likely plays an important role in the propagation and collimation of the jets; one possibility is the action of a "cosmic battery".Comment: 12 pages, 2 figures, 3 tables; accepted for publication in Astronomy & Astrophysic

Two techniques for digital filter design

Digital controllers, one using a special-purpose computer and the other using a combination of digital and analog techniques, are designed around /1/ computers that simulate the transfer function and interface with the system, and /2/ analog and digital circuits, converters, amplifiers, constant multipliers, and delay lines that form a digital filter

Observational and theoretical studies of the evolving structure of baroclinic waves

Dynamical processes involved in comma cloud formation, and passive tracer evolution in a baroclinic wave are discussed. An analytical solution was obtained demonstrating the complex nongeostrophic flow pattern involved in the redistribution of low level constituents in a finite amplitude baroclinic wave, and in the formation of the typical humidity and cloud distributions in such a wave. Observational and theoretical studies of blocking weather patterns in middle latitude flows were studied. The differences in the energy and enstrophy cascades in blocking and nonblocking situations were shown. It was established that pronounced upscale flow of both of these quantities, from intermediate to planetary scales, occurs during blocking episodes. The upscale flux of enstrophy, in particular, suggests that the persistence of blocking periods may be due to reduced dissipation of the large scale circulation and therefore entail some above normal predictability

How Much Should China Pollute?

The debate concerning how much China should pollute is at the heart of international negotiations regarding climate change and environmental protection more generally. China is the world’s leading polluter and leading emitter of greenhouse gases. It insists that it has a right to emit as much as it wants in the future. China interprets the principle of “common but differentiated responsibilities” to mean that China has a responsibility to help avoid the harmful consequences associated with climate change, but that its responsibility is different from that imposed on the United States and the rest of the developed world. In fact, there is no basis in environmental law for a right to pollute as much as someone else has already polluted. To the contrary, American law specifically rejects the idea that clean air or water can be polluted until the pollution actually causes harm. Despite its rhetoric, China has done much more to reduce its greenhouse gas emissions than it is legally obligated to do. It has acted from a variety of motivations, including a desire for global leadership, genuine environmental concern, fear of domestic instability, and the opportunity for economic growth. These gains are checked, though, by China’s unwillingness to constrain its unprecedented economic growth and its inability to employ the law to actually control emissions.This article concludes by trying to reconcile China’s rhetoric and China’s actions in an effort to solve the problems that China’s pollution poses for China, the United States, and the rest of the world. China should ensure that its pollution does not harm its own people or the rest of the world. China should commit to abiding by the rule of law to actually enforce the environmental regulations that it has enacted, and the United States can help China in that regard. The United States and China should also collaborate, compete, and commit in an effort to address the problems caused by China’s pollution

Voluntary Campaign Finance Reform

Any effort to achieve voluntary campaign finance reform raises two questions: Is it really voluntary, and does it really work? In Part I of this Essay, I examine the voluntariness of voluntary campaign finance reform. Agreements like that reached by Clinton and Lazio last year—what I term purely voluntary agreements —satisfy most legal tests for voluntariness. By contrast, the voluntariness of spending limits and other campaign restrictions that are imposed as a condition for receiving government funding of a political campaign—what I term governmentally induced agreements —is more doubtful. The extant jurisprudence recognizes that Buckley prohibits governmental actions that are more coercive than inducing, yet that jurisprudence does not go far enough in identifying coercive governmental spending. Part II examines the efficacy of voluntary campaign finance reform. Here the tables are turned. Governmentally induced agreements have generally been successful in achieving the results sought by campaign finance reformers. Purely voluntary agreements, by contrast, present serious questions about their efficacy. To date, the voluntary agreements demonstrate a surprising level of success, but the number of such agreements remains very small. The continued success of governmentally induced agreements depends upon adherence to the fine line of providing enough governmental funding to induce candidates to accept the conditions without becoming coercive. The election of the first presidential candidate to reject government funding since it was offered in 1976 demonstrates the fragility of the government funding system. Yet the ability of Clinton and Lazio to defy the pundits and persuade a disparate group of supporters to abide by their preferred restrictions suggests that purely voluntary campaign finance reform holds more promise than commonly expected. In the end, though, achievement of both types of voluntary campaign finance reform depends on whether the People really want it

CERCLA\u27s Mistakes

The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) confounds every theory of statutory interpretation. Congress hurriedly enacted CERCLA during the lame-duck period following the election of President Reagan and a Republican Senate majority in November 1980 but before they took office in January 1981. The resulting statute has been criticized for its apparently textual mistakes, sparse legislative history, conflicting purposes, and questionable public policy. Courts routinely complain about the difficulty of interpreting CERCLA under those circumstances. This article reviews several of the interpretive challenges presented by CERCLA, and suggests some broader implications for statutory interpretation more generally. CERCLA, hazardous waste, interpretation, legislative histor

How Not to Count Votes

Rutherford B. Hayes defeated Samuel Tilden by one electoral vote in the presidential election of 1876. In Fraud of the Century: Rutherford B. Hayes, Samuel Tilden, and the Stolen Election of 1876, Roy Morris, Jr. concludes that the election was stolen from Tilden by Republican partisans serving on the canvassing boards in the three Southern states - Florida, Louisiana, and South Carolina - that were still under the control of Republican governments backed by the federal army. But in Centennial Crisis: The Disputed Election of 1876, Chief Justice William H. Rehnquist defends the integrity and the actions of the Supreme Court Justices who served on the special Electoral Commission that Congress established to resolve the disputed claims about the election. The 1876 election, and the analogous difficulties attending the 2000 election, demonstrate the need to consider who counts votes in contested elections, and how to best balance the sometimes competing needs of independence, expertise, and timeliness