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  • 1
    Electronic Resource
    Electronic Resource
    The one-dimensional Coulomb potential as a generalized function and the hidden O(2) symmetry (1990)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 31 (1990), S. 1441-1444 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: The one-dimensional hydrogen atom treating the potential, –λ /||x||, is solved as a generalized function. The solutions (although nondegenerate) are nonunique unless fixed by some physical constraint. It is also shown that the hidden O(2) symmetry is a consequence of using solutions that are eigenfunctions of the operator sgn x≡x/||x||.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.528734
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  • 2
    Electronic Resource
    Electronic Resource
    MeV ion irradiation-induced creation and relaxation of mechanical stress in silica (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 4723-4732 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: In situ wafer curvature measurements were performed to study mechanical stress in amorphous SiO2 during Xe, Ne, and Er ion irradiation at energies in the 0.27–4.0 MeV range. Three phenomena are observed: network compaction, radiation-induced viscous flow, and a nonsaturating anisotropic deformation phenomenon. The radiation-induced viscosity is shown to be inversely proportional to the energy density deposited into atomic displacements. The relation between radiation-induced flow and diffusion is discussed in the context of the Stokes–Einstein relation. Viscous flow serves to relax stress, yet a continuous nonsaturating anisotropic deformation effect causes the stress in the irradiated layer to saturate at nonzero values: Xe irradiation at an energy below 3.6 MeV results in a tensile saturation stress; for higher energies a compressive stress builds up. These effects are explained in terms of competing bulk and surface deformation processes resulting from local heating of the SiO2 around the ion tracks. The macroscopic effect of deformation phenomena is illustrated by showing the surface morphology after 4.9 MeV Er irradiation of silica through a contact implantation mask. Finally, an in situ stress study of an alkali borosilicate glass is presented. In this case a fourth radiation induced effect is observed, namely, the generation and annihilation of volume occupying point defects. These defects are shown to anneal out at room temperature, following a broad spectrum of activation energies. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.359820
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  • 3
    Electronic Resource
    Electronic Resource
    Nonlocal potentials, isolated states, and Levinson's theorem (1999)
    College Park, Md. : American Institute of Physics (AIP)
    Journal of Mathematical Physics 40 (1999), S. 140-149 
    Details
    ISSN: 1089-7658
    Source: AIP Digital Archive
    Topics: Mathematics , Physics
    Notes: A compact expression for the calculation of phase shifts is derived for a potential which is the sum of local and nonlocal parts. Nonlocal potentials can support positive energy bound states, that is, states embedded in the continuous energy spectrum. These states, sometimes referred to as "isolated" states, are not associated with any poles of the S matrix. Some controversy exists in the literature on how such bound states are included in Levinson's theorem; it is found that the phase shift should be taken continuous at the energy of the bound state rather than taken to have a discontinuity of π. For simplicity, the analysis is restricted to the radial s wave Schrödinger equation and separable nonlocal potentials. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.532764
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  • 4
    Electronic Resource
    Electronic Resource
    Low energy ion beam mixing as a tool for multilayer x-ray mirror fabrication (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 2948-2950 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present low energy ion beam mixing as a tool for the fabrication of composite layers with smooth interfaces. Using this tool we make a stack of alternating layers of Si and MoxSiy. We measure composition and interfacial roughness (σ) and find x/y≈5/3 and σ≈4 A(ring). The method can be applied to reduce absorption losses in x-ray multilayer mirrors for high-resolution dispersive purposes, and to increase thermal stability of multilayers. The thickness of the mixed layers is found to be equal to the ion range. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.116364
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  • 5
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    Plasma-gun-assisted field-reversed configuration formation in a conical θ-pinch (2015)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2015-04-30
    Description: Injection of plasma via an annular array of coaxial plasma guns during the pre-ionization phase of field-reversed configuration (FRC) formation is shown to catalyze the bulk ionization of a neutral gas prefill in the presence of a strong axial magnetic field and change the character of outward flux flow during field-reversal from a convective process to a much slower resistive diffusion process. This approach has been found to significantly improve FRC formation in a conical θ -pinch, resulting in a ∼350% increase in trapped flux at typical operating conditions, an expansion of accessible formation parameter space to lower densities and higher temperatures, and a reduction or elimination of several deleterious effects associated with the pre-ionization phase.
    Print ISSN: 1070-664X
    Electronic ISSN: 1089-7674
    Topics: Physics
    Published by American Institute of Physics (AIP)
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  • 6
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    antiSMASH 3.0--a comprehensive resource for the genome mining of biosynthetic gene clusters (2015)
    Oxford University Press
    Details
    Publication Date: 2015-07-02
    Description: Microbial secondary metabolism constitutes a rich source of antibiotics, chemotherapeutics, insecticides and other high-value chemicals. Genome mining of gene clusters that encode the biosynthetic pathways for these metabolites has become a key methodology for novel compound discovery. In 2011, we introduced antiSMASH, a web server and stand-alone tool for the automatic genomic identification and analysis of biosynthetic gene clusters, available at http://antismash.secondarymetabolites.org . Here, we present version 3.0 of antiSMASH, which has undergone major improvements. A full integration of the recently published ClusterFinder algorithm now allows using this probabilistic algorithm to detect putative gene clusters of unknown types. Also, a new dereplication variant of the ClusterBlast module now identifies similarities of identified clusters to any of 1172 clusters with known end products. At the enzyme level, active sites of key biosynthetic enzymes are now pinpointed through a curated pattern-matching procedure and Enzyme Commission numbers are assigned to functionally classify all enzyme-coding genes. Additionally, chemical structure prediction has been improved by incorporating polyketide reduction states. Finally, in order for users to be able to organize and analyze multiple antiSMASH outputs in a private setting, a new XML output module allows offline editing of antiSMASH annotations within the Geneious software.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
    Published by Oxford University Press
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  • 7
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    On the use of omnidirectional sonars and downwards-looking echosounders to assess pelagic fish distributions during and after midwater trawling (2012)
    Oxford University Press
    Details
    Publication Date: 2012-12-12
    Description: Stockwell, J. D., Weber, T. C., Baukus, A. J., and Jech, J. M. 2013. On the use of omnidirectional sonars and downwards-looking echosounders to assess pelagic fish distributions during and after midwater trawling. – ICES Journal of Marine Science, 70:196–203. Small pelagic fish can play an important role in the structure and function of ecosystems, and there is increasing interest in their non-market value. At the scale of fish aggregations, however, the impact of fishing has received relatively little attention, with most effort devoted to impacts of vessel and gear avoidance on stock size estimates. We used concurrent deployment of a downwards-looking echosounder (Simrad ES60 system) and an omnidirectional sonar (Simrad SP90 system) during commercial pairtrawling operations for Atlantic herring ( Clupea harengus ) in the Gulf of Maine to examine their potential for studying the impacts of fishing on herring aggregations. We compared a number of aggregation metrics to illustrate similarities and differences between the two systems, and then qualitatively examined their properties during and after pairtrawling events to illustrate potential applications. Our results suggest that using both downwards-looking and omnidirectional systems provides complementary information on fish aggregation metrics. Future applications of these systems in before–after–control-impact (BACI) designs may help inform management agencies when evaluating potential impacts of fishing at the time and space scales of pelagic fish aggregations.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
    Published by Oxford University Press
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  • 8
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    antiSMASH 2.0--a versatile platform for genome mining of secondary metabolite producers (2013)
    Oxford University Press
    Details
    Publication Date: 2013-06-23
    Description: Microbial secondary metabolites are a potent source of antibiotics and other pharmaceuticals. Genome mining of their biosynthetic gene clusters has become a key method to accelerate their identification and characterization. In 2011, we developed antiSMASH, a web-based analysis platform that automates this process. Here, we present the highly improved antiSMASH 2.0 release, available at http://antismash.secondarymetabolites.org/ . For the new version, antiSMASH was entirely re-designed using a plug-and-play concept that allows easy integration of novel predictor or output modules. antiSMASH 2.0 now supports input of multiple related sequences simultaneously (multi-FASTA/GenBank/EMBL), which allows the analysis of draft genomes comprising multiple contigs. Moreover, direct analysis of protein sequences is now possible. antiSMASH 2.0 has also been equipped with the capacity to detect additional classes of secondary metabolites, including oligosaccharide antibiotics, phenazines, thiopeptides, homo-serine lactones, phosphonates and furans. The algorithm for predicting the core structure of the cluster end product is now also covering lantipeptides, in addition to polyketides and non-ribosomal peptides. The antiSMASH ClusterBlast functionality has been extended to identify sub-clusters involved in the biosynthesis of specific chemical building blocks. The new features currently make antiSMASH 2.0 the most comprehensive resource for identifying and analyzing novel secondary metabolite biosynthetic pathways in microorganisms.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
    Published by Oxford University Press
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  • 9
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    Heat accumulation effects in short-pulse multi-pass cutting of carbon fiber reinforced plastics (2015)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2015-09-10
    Description: The formation of a matrix evaporation zone (MEZ) in carbon fiber reinforced plastics during multi-pass laser cutting with picosecond laser pulses is studied for a wide range of pulse frequencies ( f p  = 10–800 kHz) and feed rates ( v f  = 0.002–10 m/s). Three regimes of the formation of the MEZ are found and related with different heat accumulation effects: (i) small MEZ (
    Print ISSN: 0021-8979
    Electronic ISSN: 1089-7550
    Topics: Physics
    Published by American Institute of Physics (AIP)
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  • 10
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    Observing the ocean interior in support of integrated management (2016)
    Oxford University Press
    Details
    Publication Date: 2016-09-24
    Description: Active- and passive-acoustic methods are widely used tools for observing, monitoring, and understanding marine ecosystems. From 25 to 28 May 2015, 214 scientists from 31 nations gathered for an ICES symposium on Marine Ecosystem Acoustics (SoME Acoustics) to discuss three major themes related to acoustic observations of marine ecosystems: (i) recent developments in acoustic and platform technologies; (ii) acoustic characterisation of aquatic organisms, ecosystem structure, and ecosystem processes; and (iii) contribution of acoustics to integrated ecosystem assessments and management. The development of, and access to new instruments, such as broad bandwidth systems, enables insightful ecological studies and innovative management approaches. Unresolved ecological questions and the increasing move towards ecosystem based management pose further challenges to scientists and instrument developers. Considering the SoME Acoustics presentations in the context of three previous ICES symposia on fisheries acoustics, topics increasingly emphasize ecosystem studies and management. The continued expansion of work and progress in marine ecosystem acoustics is due to the cross-disciplinary work of fisheries acousticians, engineers, ecologists, modellers, and others. An analysis of the symposium co-authorship network reveals a highly connected acoustic science community collaborating around the globe.
    Print ISSN: 1054-3139
    Electronic ISSN: 1095-9289
    Topics: Biology , Geosciences , Physics
    Published by Oxford University Press
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