5,174 research outputs found

    A Guide to Monetary Sanctions for Environment Violations by Federal Facilities

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    Many federal environmental statutes require compliance by federal agencies by providing waivers of sovereign immunity. This Article explores the availability of civil penalties against the United States through an analysis of three United States Supreme Court decisions, encompassing the Clean Water Act, the Resource Conservation and Recovery Act, and the Comprehensive Environmental Response, Compensation, and Liability Act. It reviews the holdings in these cases to determine the efficacy of the waiver of federal sovereign immunity in each of these statutes, and develops a framework for analyzing the waiver available under the Clean Air Act. Ultimately, this Article concludes that the Clean Air Act\u27s citizen suit provision is a viable, yet unused, basis to impose civil penalties against federal facilities

    Magnetic-crystallographic phase diagram of superconducting parent compound Fe1+x_{1+x}Te

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    hrough neutron diffraction experiments, including spin-polarized measurements, we find a collinear incommensurate spin-density wave with propagation vector k= \mathbf k = (0.4481(4)0120.4481(4) \, \,0 \, \, \frac1 2) at base temperature in the superconducting parent compound Fe1+x_{1+x}Te. This critical concentration of interstitial iron corresponds to x12x \approx 12% and leads crystallographic phase separation at base temperature. The spin-density wave is short-range ordered with a correlation length of 22(3) \AA, and as the ordering temperature is approached its propagation vector decreases linearly in the H-direction and becomes long-range ordered. Upon further populating the interstitial iron site, the spin-density wave gives way to an incommensurate helical ordering with propagation vector k= \mathbf k = (0.3855(2)0120.3855(2) \, \,0 \, \, \frac1 2) at base temperature. For a sample with x9(1)x \approx 9(1) %, we also find an incommensurate spin-density wave that competes with the bicollinear commensurate ordering close to the N\'eel point. The shifting of spectral weight between competing magnetic orderings observed in several samples is supporting evidence for the phase separation being electronic in nature, and hence leads to crystallographic phase separation around the critical interstitial iron concentration of 12%. With results from both powder and single crystal samples, we construct a magnetic-crystallographic phase diagram of Fe1+x_{1+x}Te for $ 5% < x <17%

    String Bit Models for Superstring

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    We extend the model of string as a polymer of string bits to the case of superstring. We mainly concentrate on type II-B superstring, with some discussion of the obstacles presented by not II-B superstring, together with possible strategies for surmounting them. As with previous work on bosonic string we work within the light-cone gauge. The bit model possesses a good deal less symmetry than the continuous string theory. For one thing, the bit model is formulated as a Galilei invariant theory in (D2)+1(D-2)+1 dimensional space-time. This means that Poincar\'e invariance is reduced to the Galilei subgroup in D2D-2 space dimensions. Naturally the supersymmetry present in the bit model is likewise dramatically reduced. Continuous string can arise in the bit models with the formation of infinitely long polymers of string bits. Under the right circumstances (at the critical dimension) these polymers can behave as string moving in DD dimensional space-time enjoying the full N=2N=2 Poincar\'e supersymmetric dynamics of type II-B superstring.Comment: 43 pages, phyzzx require

    The promise and peril of intensive-site-based ecological research: insights from the Hubbard Brook ecosystem study

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    Abstract. Ecological research is increasingly concentrated at particular locations or sites. This trend reflects a variety of advantages of intensive, site-based research, but also raises important questions about the nature of such spatially delimited research: how well does site based research represent broader areas, and does it constrain scientific discovery?We provide an overview of these issues with a particular focus on one prominent intensive research site: the Hubbard Brook Experimental Forest (HBEF), New Hampshire, USA. Among the key features of intensive sites are: long-term, archived data sets that provide a context for new discoveries and the elucidation of ecological mechanisms; the capacity to constrain inputs and parameters, and to validate models of complex ecological processes; and the intellectual cross-fertilization among disciplines in ecological and environmental sciences. The feasibility of scaling up ecological observations from intensive sites depends upon both the phenomenon of interest and the characteristics of the site. An evaluation of deviation metrics for the HBEF illustrates that, in some respects, including sensitivity and recovery of streams and trees from acid deposition, this site is representative of the Northern Forest region, of which HBEF is a part. However, the mountainous terrain and lack of significant agricultural legacy make the HBEF among the least disturbed sites in the Northern Forest region. Its relatively cool, wet climate contributes to high stream flow compared to other sites. These similarities and differences between the HBEF and the region can profoundly influence ecological patterns and processes and potentially limit the generality of observations at this and other intensive sites. Indeed, the difficulty of scaling up may be greatest for ecological phenomena that are sensitive to historical disturbance and that exhibit the greatest spatiotemporal variation, such as denitrification in soils and the dynamics of bird communities. Our research shows that end member sites for some processes often provide important insights into the behavior of inherently heterogeneous ecological processes. In the current era of rapid environmental and biological change, key ecological responses at intensive sites will reflect both specific local drivers and regional trends

    Tapping Environmental History to Recreate America’s Colonial Hydrology

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    To properly remediate, improve, or predict how hydrological systems behave, it is vital to establish their histories. However, modern-style records, assembled from instrumental data and remote sensing platforms, hardly exist back more than a few decades. As centuries of data is preferable given multidecadal fluxes of both meteorology/climatology and demographics, building such a history requires resources traditionally considered only useful in the social sciences and humanities. In this Feature, Pastore et al. discuss how they have undertaken the synthesis of historical records and modern techniques to understand the hydrology of the Northeastern U.S. from Colonial times to modern day. Such approaches could aid studies in other regions that may require heavier reliance on qualitative narratives. Further, a better insight as to how historical changes unfolded could provide a “past is prologue” methodology to increase the accuracy of predictive environmental models

    HST STIS spectroscopy of the triple nucleus of M31: two nested disks in Keplerian rotation around a Supermassive Black Hole

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    We present HST spectroscopy of the nucleus of M31 obtained with STIS. Spectra taken around the CaT lines at 8500 see only the red giants in the double bright- ness peaks P1 and P2. In contrast, spectra taken at 3600-5100 A are sensitive to the tiny blue nucleus embedded in P2, the lower surface brightness red nucleus. P2 has a K-type spectrum, but the embedded blue nucleus has an A-type spectrum with strong Balmer absorption lines. Given the small likelihood for stellar collisions, a 200 Myr old starburst appears to be the most plausible origin of the blue nucleus. In stellar population, size, and velocity dispersion, the blue nucleus is so different from P1 and P2 that we call it P3. The line-of-sight velocity distributions of the red stars in P1+P2 strengthen the support for Tremaine s eccentric disk model. The kinematics of P3 is consistent with a circular stellar disk in Keplerian rotation around a super-massive black hole with M_bh = 1.4 x 10^8 M_sun. The P3 and the P1+P2 disks rotate in the same sense and are almost coplanar. The observed velocity dispersion of P3 is due to blurred rotation and has a maximum value of sigma = 1183+-201 km/s. The observed peak rotation velocity of P3 is V = 618+-81 km/s at radius 0.05" = 0.19 pc corresponding to a circular rotation velocity at this radius of ~1700 km/s. Any dark star cluster alternative to a black hole must have a half-mass radius <= 0.03" = 0.11 pc. We show that this excludes clusters of brown dwarfs or dead stars on astrophysical grounds.Comment: Astrophysical Journal, Sep 20, 2005, 21 pages including 20 figure

    Airborne Visible/Infrared Imaging Spectrometer (AVIRIS): Recent improvements to the sensor

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    AVIRIS is a NASA-sponsored Earth-looking imaging spectrometer designed, built and operated by the Jet Propulsion Laboratory. Spectral, radiometric and geometric characteristics of the data acquired by AVIRIS are given in Table 1. AVIRIS has been operational since 1989, however in each year since 1989 major improvements have been completed in most of the subsystems of the sensor. As a consequence of these efforts, the capabilities of AVIRIS to acquire and deliver calibrated imaging spectrometer data of high quality have improved significantly over those in 1989. Improvements to AVIRIS prior to 1992 have been described previously (Porter et al., 1990, Chrien et al., 1991, & Chrien et al., 1992). In the following sections of this paper we describe recent and planned improvements to AVIRIS in the sensor task

    Isolation, characterization and partial sequencing of cystine and thiol peptides of pig heart lipoamide dehydrogenase

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    Pig heart lipoamide dehydrogenase (EC 1.6.4.3) contains ten half-cystines (as cysteic acid) per mole of enzyme bound FAD. Two of these are linked in an intrachain cystine which acts in concert with the flavin during catalysis. A peptic peptide containing this active center disulfide has been isolated and shown to have the sequence: Glu-Thr-Leu-Gly-Gly-Thr-Cys-Leu-Asn-Val-Gly-Cys-Ile-Pro-Ser (Lys, Ala, Leu). The enzyme also contains seven titratable thiols when either 5,5'-dithiobis (2-nitrobenzoic acid) or iodoacetate is used as titrant. Tryptic peptides containing alkylated thiols have been isolated and characterized by amino acid composition and by their positions in two-dimensional chromatography-electrophoresis. On the basis of map position and composition, the peptides containing thiols can be distinguished from one another. The results are compared with recent data of Brown and Perham (Brown, J. P. and Perham, R. N. (1974) Biochem. J. 138, 505-512) on the compositions and partial sequences of tryptic chymotryptic peptides containing half-cystines. The combined data associate nine of the ten half-cystines with unique compositions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22230/1/0000664.pd
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