Prominence and flare fine structure from cross-field thermal conduction

Thermal conduction across a magnetic field is strongly suppressed compared with conduction along the field. However, if a flare is heated by a highly filamented beam directed along the field, then the array of heated cells in a cross-section of the flare will result in both small spatial scales (with consequently large temperature gradients) and a large surface area for the heated volume, providing a geometrical enhancement of the total cross-field energy flux. To investigate the importance of this filamentary geometry, we present a simple model of a single heated filament surrounded by an optically thin radiating shell, obtain an analytical expression for the stable equilibrium temperature profile within the shell, and use this to impose limits on the size of filament for which this model is appropriate. We find that this mechanism by itself is capable of transporting a power of the same order as a large flare, with a moderate range of filament sizes. The length scales are substantially smaller than can be resolved at present, although they should be regarded as underestimates.Comment: 7 pages, LaTeX, 4 figures. Source, figures and PS at http://www.astro.gla.ac.uk/preprints/95-05.html . To appear in A&

The Law and Politics of the Enforcement of Federal Standards for the Administration of the Unemployment Insurance Program

Abstract for a piece in the 1995 Unemployment Compensation: Continuity and Change symposium presented by the Advisory Council on Unemployment Compensation and the University of Michigan Journal of Law Reform

Exploring Linkages Among Agriculture, Trade, and the Environment: Issues for the Next Century

Many trade and environment issues will confront agriculture over the next several years. This report provides an economic framework to better understand these issues and discusses prior empirical inquiries and findings. Four primary issues are addressed: (1) how will environmental policies affect agricultural trade?; (2) how will agricultural trade liberalization affect environmental quality?; (3) to what extent should there be international harmonization of environmental policies and product standards?; and (4) is there economic justification for using trade measures to protect the environment? This report demonstrates that basic economic paradigms can provide a basis for understanding how trade and the environment interact. The few empirical studies based on these concepts have found many of the linkages between trade and the environment to be weak or the effects small. Trade and environment issues remain important to monitor, however, because economic and environmental relationships and domestic and international policies are continually evolving, and decision-makers need good information to confirm or disprove the numerous hypotheses that have surfaced in international discussions.environmental policy, agricultural policy, trade policy, trade, environment, harmonization, Agricultural and Food Policy, Environmental Economics and Policy, International Relations/Trade,

Groups 5 and 6 Terminal Hydrazido(2−) Complexes: N_β Substituent Effects on Ligand-to-Metal Charge-Transfer Energies and Oxidation States

Brightly colored terminal hydrazido(2−) (dme)MCl_3(NNR_2) (dme = 1,2-dimethoxyethane; M = Nb, Ta; R = alkyl, aryl) or (MeCN)WCl_4(NNR_2) complexes have been synthesized and characterized. Perturbing the electronic environment of the β (NR_2) nitrogen affects the energy of the lowest-energy charge-transfer (CT) transition in these complexes. For group 5 complexes, increasing the energy of the N_β lone pair decreases the ligand-to-metal CT (LMCT) energy, except for electron-rich niobium dialkylhydrazides, which pyramidalize N_β in order to reduce the overlap between the Nb═Nα π bond and the Nβ lone pair. For W complexes, increasing the energy of N_β eventually leads to reduction from formally [W^(VI)≡N–NR_2] with a hydrazido(2−) ligand to [W^(IV)═N═NR_2] with a neutral 1,1-diazene ligand. The photophysical properties of these complexes highlight the potential redox noninnocence of hydrazido ligands, which could lead to ligand- and/or metal-based redox chemistry in early transition metal derivatives