Hydrogen safety Progress report no. 7 1 Jul. - 30 Sep. 1965

Performance characteristics of two console-type hydrogen gas detectors sampling by diffusion and convectio

Carbonate Sedimentation Rates Today and in the Past: Holocene of Florida Bay, Bahamas, and Bermuda vs. Upper Jurassic and Lower Cretaceous of the Jura Mountains (Switzerland and France)

Lagoonal to intertidal sediments from the Holocene in Florida Bay, on the Bahamas, and in Bermuda are compared to similar facies in the Kimmeridgian and Berriasian of the Swiss and French Jura Mountains. Dating by 14C permits the estimation of sediment accumulation rates in the Holocene. In the ancient outcrops, the timing is given by cyclostratigraphic analysis. Elementary depositional sequences formed in tune with the 20-ka precession cycle, although much of this time may have been spent in non-deposition and/or erosion. After decompaction of the ancient sequences, their accumulation rates can be evaluated. It is suggested that the studied Holocene sediments accumulated over the past 6000 years with rates of 0.3 to 3 mm/a, whereas the Kimmeridgian and Berriasian facies show somewhat lower rates of 0.07 to 0.6 mm/a. This difference may be due to metho­dological errors, but also to variable carbonate production. In shallow carbonate systems, much of the sediment produced may be redistributed over the platform or exported. Furthermore, basin morpho­logy and currents can strongly influence facies and thickness of the accumulated sediment. Finally, the accumulated sediment may suffer further erosion before it is preserved in the sedimentary record. Consequently, when estimating sedimentation rates in ancient sequences, it is important to do this with the highest time resolution possible, and only after having decompacted the sediment and evaluated the time lost in hiatuses or condensed intervals

The Uniform Environmental Covenants Act: Why, How, and Whether

With contaminated land, it sometimes makes sense to do a partial cleanup, rather than a complete one, and combine the cleanup with land use restrictions and continuing obligations to monitor the land. The Uniform Environmental Covenants Act creates a new state law property interest to make these restrictions and obligations permanent and enforceable. It addresses issues created by traditional common law doctrines that were hostile to permanent land restrictions, as well as more contemporary problems presented by tax liens, eminent domain, and adverse possession. This Article reviews the Act’s legal infrastructure for creating, enforcing, and modifying the terms of the land use restrictions and monitoring obligations. The Article argues that the Act’s legal infrastructure provides parties with the legal certainty needed to encourage future cleanups, while also protecting against environmental risks that the residual contamination could otherwise pose. These cleanups, often financed as part of the property’s redevelopment, are particularly useful because they are a way to return blighted properties to the stream of commerce. The Act has drawn some criticism, primarily for not going further with its protections, and these are reviewed at the end of the Article

Hydrogen safety Progress report no. 6, 1 Apr. - 30 Jun. 1965

Hydrogen safety hazards, storage, and handling - Hydrogen plume studies to determine quantity-distance criteria and guidelines for optimum placement of hydrogen detector

Overexpression of Mcl-1 exacerbates lymphocyte accumulation and autoimmune kidney disease in lpr mice

Cell death by apoptosis has a critical role during embryonic development and in maintaining tissue homeostasis. In mammals, there are two converging apoptosis pathways: the ‘extrinsic’ pathway, which is triggered by engagement of cell surface ‘death receptors’ such as Fas/APO-1; and the ‘intrinsic’ pathway, which is triggered by diverse cellular stresses, and is regulated by prosurvival and pro-apoptotic members of the Bcl-2 family of proteins. Pro-survival Mcl-1, which can block activation of the proapoptotic proteins, Bax and Bak, appears critical for the survival and maintenance of multiple haemopoietic cell types. To investigate the impact on haemopoiesis of simultaneously inhibiting both apoptosis pathways, we introduced the vavP-Mcl-1 transgene, which causes overexpression of Mcl-1 protein in all haemopoietic lineages, into Faslpr/lpr mice, which lack functional Fas and are prone to autoimmunity. The combined mutations had a modest impact on myelopoiesis, primarily an increase in the macrophage/monocyte population in Mcl-1tg/lpr mice compared with lpr or Mcl-1tg mice. The impact on lymphopoiesis was striking, with a marked elevation in all major lymphoid subsets, including the non-conventional double-negative (DN) T cells (TCRβ+ CD4– CD8– B220+ ) characteristic of Faslpr/lpr mice. Of note, the onset of autoimmunity was markedly accelerated in Mcl-1tg/lpr mice compared with lpr mice, and this was preceded by an increase in immunoglobulin (Ig)-producing cells and circulating autoantibodies. This degree of impact was surprising, given the relatively mild phenotype conferred by the vavP-Mcl-1 transgene by itself: a two- to threefold elevation of peripheral B and T cells, no significant increase in the non-conventional DN T-cell population and no autoimmune disease. Comparison of the phenotype with that of other susceptible mice suggests that the development of autoimmune disease in Mcl-1tg/lpr mice may be influenced not only by Ig-producing cells but also other haemopoietic cell types

A mapping approach to synchronization in the "Zajfman trap": stability conditions and the synchronization mechanism

We present a two particle model to explain the mechanism that stabilizes a bunch of positively charged ions in an "ion trap resonator" [Pedersen etal, Phys. Rev. Lett. 87 (2001) 055001]. The model decomposes the motion of the two ions into two mappings for the free motion in different parts of the trap and one for a compressing momentum kick. The ions' interaction is modelled by a time delay, which then changes the balance between adjacent momentum kicks. Through these mappings we identify the microscopic process that is responsible for synchronization and give the conditions for that regime.Comment: 12 pages, 9 figures; submitted to Phys Rev

Gain and Loss in Quantum Cascade Lasers

We report gain calculations for a quantum cascade laser using a fully self-consistent quantum mechanical approach based on the theory of nonequilibrium Green functions. Both the absolute value of the gain as well as the spectral position at threshold are in excellent agreement with experimental findings for T=77 K. The gain strongly decreases with temperature.Comment: 7 pages, 3 figures directly include