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  • 1
    Electronic Resource
    Electronic Resource
    Molecular Clock Calibrations and Metazoan Divergence Dates (1999)
    Springer
    Journal of molecular evolution 49 (1999), S. 385-391 
    Details
    ISSN: 1432-1432
    Keywords: Key words: Molecular clock — Divergence times — Calibration — Fossils — Metazoans — Cambrian explosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. It has recently been argued that living metazoans diverged over 800 million years ago, based on evidence from 22 nuclear genes for such a deep divergence between vertebrates and arthropods (Gu 1998). Two ``internal'' calibration points were used. However, only one fossil divergence date (the mammal–bird split) was directly used to calibrate the molecular clock. The second calibration point (the primate–rodent split) was based on molecular estimates that were ultimately also calibrated by the same mammal–bird split. However, the first tetrapods that can be assigned with confidence to either the mammal (synapsid) lineage or the bird (diapsid) lineage are approximately 288 million years old, while the first mammals that can be assigned with confidence to either the primate or the rodent lineages are 65 million years old, or 85 million years old if ferungulates are part of the primate lineage and zhelestids are accepted as ferungulate relatives. Recalibration of the protein data using these fossil dates indicates that metazoans diverged between 791 and 528 million years ago, a result broadly consistent with the palaeontological documentation of the ``Cambrian explosion.'' The third, ``external'' calibration point (the metazoan–fungal divergence) was similarly problematic, since it was based on a controversial molecular study (which in turn used fossil dates including the mammal–bird split); direct use of fossils for this calibration point gives the absurd dating of 455 million years for metazoan divergences. Similar calibration problems affect another recent study (Wang et al. 1999), which proposes divergences for metazoans of 1000 million years or more: recalibrations of their clock again yields much more recent dates, some consistent with a ``Cambrian explosion'' scenario. Molecular clock studies have persuasively argued for the imperfection of the fossil record but have rarely acknowledged that their inferences are also directly based on this same record.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/PL00006562
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  • 2
    Electronic Resource
    Electronic Resource
    Fast Photonic Switches with Ferroelectric Films (2006)
    s.l. ; Stafa-Zurich, Switzerland
    Advances in science and technology Vol. 45 (Oct. 2006), p. 2640-2647 
    Details
    ISSN: 1662-0356
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Natural Sciences in General , Technology
    Notes: Fir st prototypes of electrooptic (EO) planar deflector switches (PDS) are fabricatedwith hybrid integration on Si substrates. Planar optical modules, made in silica-on-silicontechnology, consist of input and output waveguide microlenses facing each other and slabwaveguides in between. The modules interconnect the input and output fibers with laterallycollimated light beams less than 400 [removed info]m in width at distances up to 100 mm with losses lower than3 dB. Thin lead lanthanum zirconium titanate (PLZT) films with prism-shaped electrodes grown onSrTiO3 substrates form the deflector elements. The PLZT films are more than 10 [removed info]m thick with EOcoefficients about 40 pm/V. The deflector assembly technology provides chip vertical positioningaccuracy better than 1 [removed info]m. The deflector chips are attached to the optical substrates with thermocompressionflip-chip bonding. The optical power losses of the modules with test silica chips can beas low as 3.6 dB. However, the lowest module losses achieved with PLZT are about 10 dB. Thechannel-to-channel switching operations are demonstrated at about 40 V and switching times lessthan 300 ns
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/42/transtech_doi~10.4028%252Fwww.scientific.net%252FAST.45.2640.pdf
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  • 3
    Electronic Resource
    Electronic Resource
    Closely approximating second-order Møller–Plesset perturbation theory with a local triatomics in molecules model (2000)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 112 (2000), S. 3592-3601 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A new ansatz for local electron correlation is introduced, which truncates double substitutions subject to a triatomics in molecules (TRIM) criterion. TRIM includes all double substitutions in which one occupied-virtual substitution is atomic while the other substitution can be nonlocal (a cubic number, before cutoffs). With an additional approximation, the TRIM second-order Møller–Plesset perturbation theory (MP2) model can be noniteratively solved; this is the model that is implemented. Results are shown for absolute energies of alkane and polyene chains, rotational barriers of substituted ethylenes and benzenes, and association energies of the water and neon dimers. Over 99.7% of the untruncated MP2 energy is recovered for the test cases, and the relative energies of small systems are in error by less than 0.1 kcal/mol. By contrast, a diatomics in molecules (DIM) truncation recovers about 95% of the full MP2 energy, and yields errors several times larger for relative energies. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.480512
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  • 4
    Electronic Resource
    Electronic Resource
    Protein I of Neisseria gonorrhoeae outer membrane is a porin (1981)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 12 (1981), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1981.tb07663.x
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  • 5
    Electronic Resource
    Electronic Resource
    An applet-based anonymous distributed computing system (2001)
    Bingley : Emerald
    Internet research 11 (2001), S. 35-41 
    Details
    ISSN: 1066-2243
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Computer Science
    Notes: Anonymous distributed computing systems consist of potentially millions of heterogeneous processing nodes connected by the global Internet. These nodes can be administered by thousands of organizations and individuals, with no direct knowledge of each other. This work defines anonymous distributed computing systems in general then focuses on the specifics of an applet-based approach for large-scale, anonymous, distributed computing on the Internet. A user wishing to participate in a computation connects to a distribution server, which provides information about available computations, and then connects to a computation server with a computation to distribute. A Java class is downloaded, which communicates with the computation server to obtain data, performs the computation, and returns the result. Since any computer on the Internet can participate in these computations, potentially a large number of computers can participate in a single computation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/10662240110365698
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  • 6
    Electronic Resource
    Electronic Resource
    Internet shopping, consumer search and product branding (2000)
    Bingley : Emerald
    The @journal of product & brand management 9 (2000), S. 6-20 
    Details
    ISSN: 1061-0421
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Economics
    Notes: Recent interest in the Internet as a medium for commerce has raised questions about the usefulness of branding on the World Wide Web. Examines whether consumers use brands as sources of information when shopping on the Internet. Applying theory from the economics of information, predicts that recent adopters of the Internet will be less proficient at searching for product information and will rely more on brands. As they gather more experience on the Internet, their search proficiency should rise and their brand reliance should fall. These hypotheses are tested and confirmed using usage and opinion survey data from the Internet community. The results suggest that branding can facilitate consumers' acceptance of electronic commerce.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1108/10610420010316302
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  • 7
    Electronic Resource
    Electronic Resource
    In Situ Measurement and Numerical Simulation of Oxygen Limited Biotransformation (1989)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 9 (1989), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Enhanced subsurface biorestoration is rapidly becoming recognized as a valuable tool for the restoration of hydrocarbon-contaminated aquifers and sediments. Previous field and laboratory studies at a former wood creosoting facility near Conroe, Texas, have indicated that insufficient oxygen is the primary factor limiting the biotransformation of polynuclear aromatics (PNAs) in sediments and ground water at this site. A series of laboratory experiments and field push-pull injection tests were performed as part of this project to: (1) study the effect of low oxygen concentrations on the biotransformation of PNAs; (2) identify the minimum concentration of PNAs that could be achieved through the addition of oxygen alone; (3) confirm that enhanced subsurface biorestoration is feasible at this site; and (4) test an existing numerical model of the biotransformation process (BIOPLUME). The laboratory studies demonstrated that biotransformation of the PNAs was not inhibited at dissolved oxygen concentrations as low as 0.7 mg/L although this work did suggest that there may be a minimum PNA concentration of 30 to 70 μg/L total PNAs below which biotransformation was inhibited. The field push-pull tests confirmed that addition of oxygen was effective in enhancing the subsurface biodegradation of the PNAs. The minimum concentration achieved using oxygen alone was approximately 60 μg/L total PNAs. Minimal biotransformation of these compounds was observed without oxygen addition. The numerical model BIOPLUME was tested against monitoring data from the field experiments and appears to provide a good approximation of the biodegradation process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1989.tb01123.x
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  • 8
    Electronic Resource
    Electronic Resource
    Investigation and Remediation of a 1,2–Dichloroethane Spill Part I: Short and Long-Term Remediation Strategies (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 19 (1999), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: Release of an estimated 150,000 gallons (568,000 L).of 1.2–dichloroethane (EDC) from a buried pipeline into a ditch and surrounding soil resulted in shallow subsurface contamination of a Gulf Coast site. Short-term remediation included removal of EDC DNAPI. (dense nonaqueous phase liquid) by dredging and vacuuming the ditch, and by dredging the river where the ditch discharged. EDC saturation in shallow impacted sediments located beneath the ditch was at or below residual saturation and these sediments were therefore left in place. The ditch was lined, backfilled, and capped. Long-term remediation includes EDC DNAPL recovery and hydraulic containment from the shallow zone with long-term monitoring of the shallow, intermediate, and deep (200 foot) aquifers. Ground water, DNAPL., and dissolved phase models were used to guide field investigations and the selection of an effective remedial action strategy. The DNAPL. modeling was conducted for a two-dimensional vertical cross section of the site, and included the three aquifers separated by two aquitards with microfractures. These aquitards were modeled using a dual porosity approach. Matrix and fracture properties of the aquitards used for DNAPL modeling were determined from small-scale laboratory properties. These properties were consistent with effective hydraulic conductivity determined from ground water flow modeling. A sensitivity analysis demonstrated that the vertical migration of EDC was attenuated by dissolution of EDC into the matrix of the upper aquitard. When the organic/water entry pressure of the aquitard matrix, or the solubility of EDC were decreased to unrealislically low values. EDC DNAPL. accumulated in the aquifer below the upper aquitard.EDC DNALM, did not reach the regional (deepest) aquifer in any of the cases modeled. The limited extent of vertical EDC migration predicted is supported by ground water monitoring conducted over the four years since the spill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1999.tb00226.x
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  • 9
    Electronic Resource
    Electronic Resource
    Investigation and Remediation of a 1,2-Dichloroethane Spill Part II: Documentation of Natural Attenuation (1999)
    Oxford, UK : Blackwell Publishing Ltd
    Ground water monitoring & remediation 19 (1999), S. 0 
    Details
    ISSN: 1745-6592
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A release of 1,2-dichloroethane. also known as ethylene dichloride (EDC), resulted in shallow subsurface freephase contamination of a Gulf Coast site in the southern United States. The site stratigraphy consists primarily of a low permeability, surficial peat. silt, and clay zone underlain by fractured clay; a confined 12 in deep sand ground water flow zone; a confined 21 m deep fine sand zone of limited ground water flow, followed by a deep aquitard. The Gumbo clay and sandy clay aquitard below the release area overlies and protects the 61 m deep Upper Chicot Aquifer, which is a confined regional aquifer. An ongoing recovery and hydraulic containment program from the primary impacted and laterally and vertically restricted shallow 40-foot sand zone has effectively recovered dense nonaqueous phase liquid (DNAPL) and contained dissolved phase EDC.Natural attenuation of EDC was demonstrated through (1) a laboratory microcosm study substantiating the ability of the native microbial population in the deeper aquifer lo degrade EDC under anaerobic environmental conditions found at the site. (2) field investigations showing reductions in EDC concentrations over time in many of the wells on site, and (3) an evaluation of the ground water for EDC and its degradation products and oilier geo-chemical parameters such as dissolved oxygen, redox potential, and pH. Degradation products of EDC found in the field investigations included 2-chloroeihanol, ethanol. ethene, and ethane. Dissolved EDC concentrations in selected wells between the first recorded samples and the fourth quarter of 1997 ranged from greater than 4% to 99% reductions. First-order exponential decay half-lives ranged from 0.21 to 4.2 years for wells showing decreases in FDC concentrations over time. Elevated methane concentrations indicated carbon dioxide to be the major terminal electron acceptor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1745-6592.1999.tb00227.x
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  • 10
    Electronic Resource
    Electronic Resource
    Dermal cylindroma and eccrine spiradenoma (1996)
    Oxford, UK : Blackwell Publishing Ltd
    Australasian journal of dermatology 37 (1996), S. 0 
    Details
    ISSN: 1440-0960
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Multiple dermal cylindromas on the scalp and back and eccrine spiradenoma on the face of a 59 year old woman are described. A case for a common origin is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-0960.1996.tb00995.x
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