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  • 2000-2004  (124)
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  • 1
    Electronic Resource
    Electronic Resource
    Dielectric control of electrostatic barriers for molecular electronics (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 114-116 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We describe an approach for controlling electrostatic barriers in molecular electronics devices which uses anisotropic dielectric material to modify the analytic form of the effective electrostatic interactions within the device. We study the one-dimensional geometry relevant to interfaces between carbon nanotubes and find that the bound charge induced in a uniaxial dielectric can replace the bare electrostatic interaction between charges with separation z by an effective −log(z) interaction or a confining |z| interaction. We use these models to study the depletion region formed at heterojunctions between segments of doped carbon nanotubes. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1336162
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  • 2
    Electronic Resource
    Electronic Resource
    THE ROLE OF KNOX GENES IN PLANT DEVELOPMENT# (2004)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Cell and Developmental Biology 20 (2004), S. 125-151 
    Details
    ISSN: 1081-0706
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: knox genes encode homeodomain-containing transcription factors that are required for meristem maintenance and proper patterning of organ initiation. In plants with simple leaves, knox genes are expressed exclusively in the meristem and stem, but in dissected leaves, they are also expressed in leaf primordia, suggesting that they may play a role in the diversity of leaf form. This hypothesis is supported by the intriguing phenotypes found in gain-of-function mutations where knox gene misexpression affects leaf and petal shape. Similar phenotypes are also found in recessive mutations of genes that function to negatively regulate knox genes. KNOX proteins function as heterodimers with other homeodomains in the TALE superclass. The gibberellin and lignin biosynthetic pathways are known to be negatively regulated by KNOX proteins, which results in indeterminate cell fates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.cellbio.20.031803.093824
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  • 3
    Electronic Resource
    Electronic Resource
    European vs. American approaches to institutionalisation of business ethics: the Spanish case (2002)
    Oxford, UK and Boston, USA : Blackwell Publishers Ltd
    Business ethics 11 (2002), S. 0 
    Details
    ISSN: 1467-8608
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Philosophy , Economics
    Notes: This paper reports on a study of the largest Spanish corporations concerning the status of corporate ethics policies. The research project, the first of its kind in Spain, has two parts. First, the types of formal documents the companies use are analysed, including those dealing with ethical values or norms. Three groups of companies are distinguished: the first group has no formal documents dealing with ethical values, and the reasons given for not having any ethical statement are discussed. A second group has one document mentioning ethical values (generally the vision and/or mission statement), and a third group has in place two or more documents (one generic and the other more detailed, such as a code of conduct). The findings show that the latter group is more proactive than the former in implementing measures for promoting business ethics throughout the organisation. In the second part of the research, the study analyses the differences between companies whose headquarters are in Spain, Europe and USA regarding the arguments, the focus and the practices used to formalise business ethics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/1467-8608.00273
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  • 4
    Electronic Resource
    Electronic Resource
    Chemical stability of doped ZnO thin films (2000)
    Springer
    Journal of materials science 11 (2000), S. 1-5 
    Details
    ISSN: 1573-482X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We present the results of a chemical etching stability study carried out on ZnO thin films doped with several elements deposited by spray pyrolysis. Prior to the etching, a structural study was done by X-ray diffraction and the texture of the samples was obtained by scanning electron microscopy. The samples were etched employing a solution of dilute hydrochloric acid. The etching rates obtained for the different samples depend on the dopant element and our results confirm that films doped with Cr present the highest stability against chemical etching.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1008973800554
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  • 5
    Electronic Resource
    Electronic Resource
    Isolation and molecular characterisation of the gene encoding the cytoplasmic ribosomal protein S28 in Prunus persica [L.] Batsch (2000)
    Springer
    Molecular genetics and genomics 263 (2000), S. 201-212 
    Details
    ISSN: 1617-4623
    Keywords: Key wordsPrunus persica ; Ribosomal proteins ; Gene expression ; Gene regulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract RT-PCR was performed on peach (Prunus persica [L.] Batsch) RNA to isolate cDNAs corresponding to transcripts which are differentially expressed in leaves borne on basal and apical shoots. A gene was identified which was more highly expressed in the leaves of basal shoots, and codes for the cytoplasmic protein S28 present in the small ribosomal subunit. The 5′ leader regions of RPS28 mRNAs were found to harbour 8–11 pyrimidine tracts, which suggested similarities to regulatory stretches that control the translation of mRNAs for ribosomal proteins in animals. The peach S28 is encoded by two intron-containing genes, which are both transcribed in mitotically active tissues such as developing leaves and roots. In situ hybridisation to shoot vegetative apices and the measurement of nucleus/nucleolus ratios indicated that RPS28 expression was confined to areas undergoing active cell division. The mature RPS28 mRNA was detected as a single species in actively dividing tissues such as apical tips, developing leaves, vegetative buds, stamens, developing fruits and roots. In contrast, accumulation of a precursor RNA, in the presence of the mature product, was found in fully expanded leaves and subtending stems, while only the precursor species was detected in several late-stage tissues. This phenomenon suggested that expression of the mature RNA is controlled at the level of splicing and turnover of the precursor RNA. This is similar to the mode of regulation of ribosomal protein genes in animals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004380051161
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  • 6
    Electronic Resource
    Electronic Resource
    Regeneration and genetic transformation of Spanish rice cultivars using mature embryos (2000)
    Springer
    Euphytica 114 (2000), S. 117-122 
    Details
    ISSN: 1573-5060
    Keywords: genetic transformation ; japonica rice cultivar ; mature embryo ; Oryza sativa ; plant regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract To establish a plant regeneration system from embryogenic callus derived from mature rice embryos, the addition of aminoacids and the effect of two macronutrient solutions MSD and N6D to the basal callus induction medium was tested in three Spanish varieties, Senia, Tebre and Bahia. Aminoacids enhanced the production of embryogenic callus in Tebre and Senia whereas in the case of Bahia, embryogenic callus, which gave rise to a high rate of differentiated shoots, was induced without aminoacids. The macronutrient solution had also to be adjusted for each variety. Pre-regeneration treatment with ABA significantly improved the regeneration rate in all media tested, independently of the media in which the embryogenic callus were induced. In a comparison of growth regulators, BA yielded more shoots than Kin in all varieties whereas the effect of the auxins NAA or IAA was dependent on the variety. Transgenic plants from the three varieties were obtained via an Agrobacterium tumefaciens transformation system, using the optimised culture media.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1003941913609
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  • 7
    Electronic Resource
    Electronic Resource
    Spatio-temporal distribution of seismic activity during the Umbria-Marche crisis, 1997 (2000)
    Springer
    Journal of seismology 4 (2000), S. 377-386 
    Details
    ISSN: 1573-157X
    Keywords: Seismicity ; Central Italy ; Umbria-Marche ; Aftershock sequence ; seismic crisis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract We present the spatio-temporal distribution of more than 2000 earthquakesthat occurred during the Umbria-Marche seismic crisis, between September 26and November 3, 1997. This distribution was obtained from recordings of atemporary network that was installed after the occurrence of the first two largest shocks (Mw =, 5.7, Mw = 6.0) of September 26. This network wascomposed of 27 digital 3-components stations densely distributed in theepicentral area. The aftershock distribution covers a region of about 40 km long and about2 km wide along the NW-SE central Apennines chain. The activity is shallow,mostly located at less than 9 km depth. We distinguished three main zonesof different seismic activity from NW to SE. The central zone, that containsthe hypocenter of four earthquakes of magnitude larger than 5, was the moreactive and the more complex one. Sections at depth identify 40–50°dipping structures that agree well with the moment tensor focalmechanisms results. The clustering and the migration of seismicity from NW to SE and the generalfeatures are imaged by aftershock distribution both horizontally and at depth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026568419411
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  • 8
    Electronic Resource
    Electronic Resource
    Study of site effects in the area of Nocera Umbra (Central Italy) during the 1997 Umbria-Marche seismic sequence (2000)
    Springer
    Journal of seismology 4 (2000), S. 555-565 
    Details
    ISSN: 1573-157X
    Keywords: Nocera Umbra ; site effects ; weak motions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract During the ML = 5.6 and 5.8 earthquakes occurredin central Italy on 26 September 1997 the historiccentre of Nocera Umbra, lying on top of a 120 m highhill, was diffusely damaged (VII-VIII degrees of MCSintensity). Some recently built houses in the modernpart of the town suffered an even higher level ofdamage. A temporary seismic array was deployed toinvestigate a possible correlation between localamplifications of ground motion in this area and theobserved pattern of damage. After a geologic andmacroseismic survey, eight sites were selected asrepresentative of different local conditions, such astopographic irregularities, sharp hard-to-softlithology transitions, alluvium-filled valleys, andboth undisturbed and deformed rocks.Horizontal-to-vertical spectral ratios for bothmicrotremor and earthquake recordings, as well asspectral ratios referred to undisturbed rock sites,were used to quantify local variations of groundmotion. In spite of the diffuse damage in the historiccentre of Nocera Umbra, a small amplification isobserved at the stations on the hill's top. Thissuggests that the higher vulnerability of the ancientbuildings mainly accounts for the diffuse damage inthat part of the town. In the frequency band ofengineering interest (1 to 10 Hz) the largestamplifications of ground motion are found at softsites: in the Topino river valley, where many episodesof severe structural damage occurred, spectralamplification is significant over a broad frequencyband ranging from 2 Hz to more than 20 Hz. Inparticular, in the central part of the valley highamplification (〉 4) is found from 3 to 10 Hz,reaching a maximum of 20 around 4 Hz. At the edge ofthe valley, close to the soil-to-rock transition,amplification is as large as 10 in a frequency bandranging from 4 to more than 20 Hz. A significantamplification (by a factor of 10 around 10 Hz) isobserved also at one of the rock sites, possibly dueto the presence of a cataclastic zone related to theactivity of a regional fault that altered themechanical properties of the rock.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026510300469
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  • 9
    Electronic Resource
    Electronic Resource
    Large amplification of ground motion at rock sites within a fault zone in Nocera Umbra (central Italy) (2000)
    Springer
    Journal of seismology 4 (2000), S. 543-554 
    Details
    ISSN: 1573-157X
    Keywords: fault zone ; ground motion ; Nocera Umbra ; site effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract During the two mainshocks of September 26, 1997 inthe Umbria-Marche border a strong-motion accelerographrecorded peak ground accelerations as large as 0.6 g,approximately, in the town of Nocera Umbra, atdistances of 10 to 15 km from the epicentres. Thisvalue is significantly larger than expected on thebasis of the usual regressions with magnitude anddistance. A broad-band amplification up to a factor of10 was consistently estimated in previous papers,using both weak and strong motion data recorded at theaccelerograph site during local moderate earthquakes.To study the cause of this amplification we deployedsix seismologic stations across the tectonic contactbetween the Ceno-Mesozoic limestone and the Mesozoicmarly sandstone where the accelerograph is installed.Seismograms of 21 shallow aftershocks in the magnituderange from 2.2 to 4.0 and a subcrustal Mw = 5.3event are analysed. Regardless of epicentre location,waveforms show a large complexity in an approximately200 m wide band adjacent to the tectonic contact. Thisis interpreted as the effect of trapped waves in thehighly fractured, lower velocity materials within thefault zone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1026559901378
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  • 10
    Electronic Resource
    Electronic Resource
    The Influence of Ag and Ag(In) Alloy on Y–Ba–Cu–O Equilibrium Diagram Around the Y-123 Superconducting Phase (2000)
    Springer
    Journal of thermal analysis and calorimetry 61 (2000), S. 539-549 
    Details
    ISSN: 1572-8943
    Keywords: alloy ; superconductor ; Y–Ba–Cu–O equilibrium diagram
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract We studied the chemical compatibility of Ag, Ag(In)alloy, Y2BaCuO5 (the so-called Y-211 green phase) and YBa2Cu3O7–δ (Y-123) phase in order to check if better grain growth and alignment with minimum contamination were possible during the Y-123melt texturing. We demonstrate that the addition of silver to Y-123 always led to an enhanced texture. The typical microstructure of the composite Y-123 plus Y-211 (that is believed essential for high critical currents in these High Tc superconductors) was not disturbed by addition of silver up to 7.5 wt%, while higher concentrations of metal led to a degradation of the texture. DTA–TG analysis was used to investigate the influence of Ag and Ag(In) alloy on the Y–Ba–Cu–O equilibria around the Y-123 phase. We found a very unexpected thermal behaviour, similar to an eutectic equilibrium, when the silver concentration was increased to35 wt%. We believe that this effect was essentially due to the increasingly higher concentration of silver that could react with the secondary phases present in the melt.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1010181820663
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