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  • Springer  (116)
  • Wiley-Blackwell  (13)
  • Washington, DC : United States Gov. Print. Off.
  • 1995-1999  (71)
  • 1985-1989  (58)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 12 (1999), S. 135-146 
    ISSN: 1434-6036
    Keywords: PACS. 73.40.Gk Tunneling - 03.65.Bz Foundations, theory of measurement, miscellaneous theories (including Aharonov Bohm effect, Bell inequalities, Berry's phase) - 05.60.Gg Quantum transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: This paper is concerned with the transmission time of an incident Gaussian wave packet through a symmetric rectangular barrier. Following Hartman (J. Appl. Phys. 33, 3427 (1962)), the transmission time is usually taken as the difference between the time at which the peak of the transmitted packet leaves the barrier of thickness and the time at which the peak of the incident Gaussian wave packet arrives at the barrier. This yields a corresponding transmission velocity which appears under certain conditions as a supervelocity, i.e. becomes larger than the corresponding propagation velocity in free space which is the group velocity for electrons or the velocity of light for photons, respectively. By analysing the propagation of a broadband wave packet (which leads in free space to an extremely concentrated wave packet at a certain time) we obtain the pulse response function of the barrier and show that the insertion of the barrier is physically unable to produce a supervelocity. Therefore, the peak of an incident Gaussian wave packet and the peak of the transmitted wave packet are in no causal relationship. The shape of the transmitted wave packet is produced from the incident wave by convolution with the pulse response of the barrier. This yields a distortion of the shape of the wave packet which includes also the observed negative time shift of the peak. We demonstrate further that the phenomenon of Hartman's supervelocities is not restricted to barriers with their exponentially decaying fields but occurs for instance also in transmission lines with an inserted LCR circuit.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 17 (1988), S. 355-363 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Tolerance to mercury in two populations of the grass shrimpPalaemonetes pugio was examined at different stages of this animal's life cycle. One population came from a mercury-contaminated creek, Piles Creek (PC), near industrialized Linden, New Jersey. The other population came from a relatively clean area, Big Sheepshead Creek (BSC), near non-industrialized Tuckerton, New Jersey. Larval grass shrimp showed no significant difference between populations in terms of mortality in 0.01 mg/L HgCl2, although treated BSC larvae metamorphosed significantly (P 〈 0.05) more slowly than their respective control group. While no BSC larvae survived the 0.0125 mg/L methylmercuric chloride (meHg) treatment, PC larvae exposed to 0.0125 mg/L meHg survived as well as their controls, indicating enhanced tolerance to meHg in this population. Adult shrimp were exposed for 14 days to control, 0.025 mg/L meHg, 0.025 mg/L HgCl2, 0.05 mg/L meHg, or 0.05 mg/L HgCl2 PC shrimp were significantly (P 〈 0.05) more tolerant to both 0.025 mg/L meHg, and 0.025 mg/L HgCl2 than were the BSC adults. Polyacrylamide gel electrophoresis suggests that both populations of shrimp are capable of producing a metallothionein like protein (MT) in response to treatment with HgCl2; MT is found in higher levels in field-caught PC shrimp than in field-caught BSC shrimp. MT was not present in field-collected, viable eggs from either population.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 34 (1998), S. 313-322 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract. To ascertain the extent of impacts from CCA-treated wood bulkheads, we sampled sediments along 10-m transects from these bulkheads and from reference sites (either bulkheads made of other materials or unbulkheaded areas nearby) and analyzed the fine fraction for metals. We ascertained metal content in resident biota, and analyzed species richness, Shannon-Wiener diversity index, and biomass of the benthic community. We found accumulation of metals in the fine-grained portion of nearby sediments and reduction in the biotic community nearby (generally at 0 and 1 m); such gradients were generally not seen in reference transects. At two of the sites there was evidence for secondary reduction of the community out further to 3 or 10 m, where the metals in the fines were lower but the percent fines was greatly increased. At all the other sites, impacts were generally limited to 0 and 1 m. The lack of reduction at further distances at the other sites is attributed to factors such as the age of the bulkheads, high energy of the environment, or nature of the sediments at those sites.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Archives of environmental contamination and toxicology 17 (1988), S. 569-574 
    ISSN: 1432-0703
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Notes: Abstract Fertilized eggs of the killifish,Fundulus heteroclitus, were exposed experimentally to methylmercury (MeHg) to evaluate whether this compound induced cytogenetic effects expressed in the embryos. An additional objective was to assess cytogenetically whetherFundulus embryos from groups that were determined to be more susceptible to the teratogenic effects of MeHg were also more susceptible to its mutagenic effects. Embryos exposed to 0.05 mg/L MeHg for 1 and 7 days post-fertilization were preserved in 10% formalin for cytological examination, while unfixed embryos from the same clutches were evaluated for teratogenic effects. Untreated embyros from each clutch served as controls. Cytogenetic-cytological analyses of fixed treated susceptible embryos that exhibited teratogenic effects revealed decreased mitotic counts (5.0-fold), and increased chromosomal aberrations (2.5-fold) when compared to their controls. There were also decreased mitotic counts (∼1.5-fold) and increased chromosomal aberrations (∼2-fold) in embryos from resistant groups when compared to their controls. Exposure to MeHg also retarded development. Forty to fifty percent of the susceptible and resistant control embryos reached the tail-bud stage, but only 28% of the treated resistant and none of the treated susceptible embryos reached this stage. There was also a significant correlation (P 〈 0.05) between teratogenic and mutagenic effects of MeHg in early stages ofFundulus.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1777
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. The Pactolus gene encodes a cell surface protein similar to that of the β integrin subunit family. The murine Pactolus gene is comprised of 16 exons that encompass 24 kb of the genome. The genomic organization of the Pactolus gene is very similar to that described for the human β2 integrin gene (and deduced for murine β2 integrin), including a separate exon containing only 5′ untranslated sequences. The Pactolus gene was mapped to a terminal region of murine Chromosome (Chr) 16, distinct from the previously mapped site of the β2 integrin gene on murine Chr 10. The Pactolus gene encodes three distinct transcripts via alternative splicing. The Pactolus A transcript encodes the full-length protein including transmembrane and cytoplasmic domains, while the Pactolus B transcript truncates translation before reaching these membrane-anchoring sequences. A newly discovered form, Pactolus C, is found in neonatal samples (along with Pactolus A) and would also encode a prematurely terminated protein. This form is derived from an alternative splicing event that skips part of exon 11, deletes exon 12, and uses an alternative acceptor site upstream of exon 13. The formation of the Pactolus B and C forms is thus governed by a complex alternative splicing mechanism that is affected by the developmental status of the animal.
    Type of Medium: Electronic Resource
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  • 6
    Publication Date: 1988-09-01
    Print ISSN: 0090-4341
    Electronic ISSN: 1432-0703
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by Springer
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  • 7
    Publication Date: 1988-05-01
    Print ISSN: 0090-4341
    Electronic ISSN: 1432-0703
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by Springer
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  • 8
    Publication Date: 1998-05-01
    Print ISSN: 0090-4341
    Electronic ISSN: 1432-0703
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Published by Springer
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  • 9
    Publication Date: 1999-10-01
    Print ISSN: 1434-6028
    Electronic ISSN: 1434-6036
    Topics: Physics
    Published by Springer
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 25 (1995), S. 569-571 
    ISSN: 1572-8854
    Keywords: PyrrolenineN-oxide ; hydrogen bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 2-Amino-5,5′-di(β-cyanoethyl)-1,2-pyrrolenineN-oxide monohydrate, C10H14N4O·H2O, crystallizes from MeCN in space group P212121 witha=7.0007(5),b=8.2998(6),c=20.8418(13) Å,V=1211.0(2) Å3,Z=4. The structure was refined toR=0.034 andR w=0.044 for 2325 observed reflections. The pyrrolenine ring adopts a nearly planar conformation, with maximum deviation from planarity 0.089(2) Å. The N−O distance is 1.345(2) Å. The water molecule bridges two pyrrolenine molecules via hydrogen bonds to theirN-oxide oxygen atoms, and also accepts a hydrogen bond from the NH2 group of another pyrrolenine molecule.
    Type of Medium: Electronic Resource
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