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  • 1
    Electronic Resource
    Electronic Resource
    Expression of pharyngeal gill-specific genes in the ascidian Halocynthia roretzi (1996)
    Springer
    Development genes and evolution 206 (1996), S. 218-226 
    Details
    ISSN: 1432-041X
    Keywords: Key words Ascidians ; Pharyngeal gill ; Specific gene expression ; Origin of chordates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The most primitive chordates may have arisen with a shift to internal feeding through the use of the pharyngeal gill slits and endostyle for extracting suspended food from the water. Therefore, the pharyngeal gill and endostyle, in addition to notochord and nerve cord, are structures key to an understanding of the molecular developmental mechanisms underlying the origin and evolution of chordates. In this and a following study, isolation of cDNA clones for genes that are specifically expressed in the pharyngeal gill or endostyle in the ascidian Halocynthia roretzi was attempted. Differential screening of a pharyngeal gill cDNA library and an endostyle cDNA library with total pharyngeal-gill cDNA probes yielded cDNA clones for two pharyngeal gill-specific genes, HrPhG1 and HrPhG2. Northern blot analysis showed a 3.0-kb transcript of HrPhG1 and a 2.0-kb transcript of HrPhG2. Predicted amino acid sequences of the gene products suggested that both genes encode secretory proteins with no significant match to known proteins. In adults, both HrPhG1 and HrPhG2 genes were only expressed in the pharyngeal gill and not in other tissues including the endostyle, body-wall muscle, gonad, gut and digestive gland. HrPhG1 and HrPhG2 transcripts were undetectable in embryos and larvae, and were first detected in juveniles 3 days after initiation of metamorphosis. In situ hybridization revealed that the expression of HrPhG1 and HrPhG2 was restricted to differentiating pharyngeal-wall epithelium, with intense signals in the area surrounding the stigma or gill slit. These genes may serve as probes for further analyses of molecular mechanisms underlying the occurrence of pharyngeal gill and formation of gill slits during chordate evolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004270050047
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  • 2
    Electronic Resource
    Electronic Resource
    Expression of endostyle-specific genes in the ascidian Halocynthia roretzi (1996)
    Springer
    Development genes and evolution 206 (1996), S. 227-235 
    Details
    ISSN: 1432-041X
    Keywords: Key words Ascidians ; Endostyle ; Specific gene expression ; Origin of chordates
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The endostyle is a special organ in the pharynx of Urochordata, Cephalochordata and Cyclostomata. This organ may have arisen in their common ancestor with a shift to internal feeding for extracting suspended food from the water. In addition, the endostyle has functional homology to the vertebrate thyroid gland. The endostyle is therefore another key structure in the understanding of the origin and evolution of chordates. Following a previous report of the pharyngeal gill-specific genes, we report here the isolation and characterization of cDNA clones for endostyle-specific genes HrEnds1 and HrEnds2 of the ascidian Halocynthia roretzi. These cDNA clones were obtained by differential screening of an endostyle cDNA library and a pharyngeal gill cDNA library with total endostyle cDNA probes. Both transcripts were abundant in the library; each represented about 10% of the cDNA clones of the library. The HrEnds1 transcript was small in size, about 600 bp in length. Although the predicted amino acid sequence of the gene product showed no similarity to known proteins, mean hydropathy profiles suggested that HrENDS1 is a type Ib protein or secreted protein. The HrEnds2 transcript was about 2.5 kb in length. Although the HrEnds2 gene product showed no sequence similarity to known proteins, mean hydropathy profiles suggested that HrENDS2 is a secreted protein. The transcripts of both genes were not detected in embryos, larvae and early juveniles but were evident in 1-month-old young adult after several compositional zones were organized in the endostyle. In situ hybridization revealed that distribution of transcripts of both genes was restricted to zone 6, the protein-secreting glandular element of the endostyle. These genes may be useful for further analysis of molecular mechanisms involved in endostyle development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004270050048
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  • 3
    Electronic Resource
    Electronic Resource
    Expression patterns of musashi homologs of the ascidians, Halocynthia roretzi and Ciona intestinalis (2000)
    Springer
    Development genes and evolution 210 (2000), S. 162-165 
    Details
    ISSN: 1432-041X
    Keywords: Key words Ascidian ; Musashi ; RNA-binding protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The gene family encoding RNA-binding proteins includes important regulators involved in the neurogenesis in both protostomes and deuterostomes. We isolated cDNAs of the ascidian homolog of one of the RNA-binding proteins, MUSASHI, from Halocynthia roretzi and Ciona intestinalis. The predicted amino acid sequences contained two RNA-recognition and RNA-binding motifs in the N-terminus and an ascidian-specific YG-rich domain in the C-terminus. Maternal transcripts of musashi were ubiquitous in early cleavage-stage embryos. Ascidian musashi had three domains of zygotic expression: the brain, nerve cord, and mesenchyma. The temporal order of the onset in these domains was highly divergent between the two species of ascidian examined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004270050024
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  • 4
    Electronic Resource
    Electronic Resource
    Further Characterisation of the 91500 Zircon Crystal (2004)
    Oxford, UK : Blackwell Publishing Ltd
    Geostandards and geoanalytical research 28 (2004), S. 0 
    Details
    ISSN: 1751-908X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: This paper reports the results from a second characterisation of the 91500 zircon, including data from electron probe microanalysis, laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS), secondary ion mass spectrometry (SIMS) and laser fluorination analyses. The focus of this initiative was to establish the suitability of this large single zircon crystal for calibrating in situ analyses of the rare earth elements and oxygen isotopes, as well as to provide working values for key geochemical systems. In addition to extensive testing of the chemical and structural homogeneity of this sample, the occurrence of banding in 91500 in both backscattered electron and cathodoluminescence images is described in detail. Blind intercomparison data reported by both LA-ICP-MS and SIMS laboratories indicate that only small systematic differences exist between the data sets provided by these two techniques. Furthermore, the use of NIST SRM 610 glass as the calibrant for SIMS analyses was found to introduce little or no systematic error into the results for zircon. Based on both laser fluorination and SIMS data, zircon 91500 seems to be very well suited for calibrating in situ oxygen isotopic analyses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1751-908X.2004.tb01041.x
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  • 5
    Electronic Resource
    Electronic Resource
    Numerical simulation of cesium cooling effects in H− ion source : The 8th international conference on ion sources (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 880-882 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Cesium volume reactions are included in a two-point model numerical code for a high power hydrogen negative ion source. The energy balance equation for the electron temperature and rate equations of Cs and Cs+ are included in our code to investigate the electron cooling and volume effects by cesium seeding. Cesium density in the ion source is taken as a variable for the calculation. Cesium is ionized over 95% in the driver region of the ion source. The electron temperature begins to decrease at cesium density 1011 cm−3 and the electron density increases because of the ionization of cesium. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1150320
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  • 6
    Electronic Resource
    Electronic Resource
    Relation between vapor Cs and adsorbed Cs in H− ion source : The 8th international conference on ion sources (2000)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 877-879 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The relation between gaseous Cs density and the coverage of Cs on the plasma grid surface is determined in the existence of the effect of Cs deposit on the cold surface. An equation for the deposit of Cs on the cold surface in the ion source is obtained by considering the saturation of the deposit. The Cs coverage is expressed as a function of gaseous Cs density in the volume of the ion source by considering the relation τθ(very-much-less-than)τa, where τθ is the time scale of the Cs adsorption to the plasma grid surface and τa is that of the Cs adsorption to the cold surface. The coverage varies with the slow time scale through the variation of the gaseous density related to the deposit of Cs on the cold surface. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1150319
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  • 7
    Electronic Resource
    Electronic Resource
    Numerical simulation of the effect of Cs volume reaction in an H− ion source : Proceedings of the 7th international conference on ion sources (1998)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 1132-1134 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Effects of cesium related reactions are investigated using a simulation code for H− ion sources. Effects begin to appear when cesium density is 1011 cm−3, but are still small and become large when the cesium density is greater than 1012 cm−3. The H− density decreases due to electron detachment. Decreasing the plasma potential by cesium seeding results in 12% smaller H− density. The minimum of the plasma potential shown experimentally by Bacal is found to correspond to a cesium coverage of 50% with the use of Langmuir adsorption isotherm. Surface production is effective only when the cesium density is around 1011 cm−3. For cesium density greater than 1012 cm−3, the effect of the cesium related volume reaction becomes larger. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1148646
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  • 8
    Electronic Resource
    Electronic Resource
    Estimate of cusp loss width in multicusp negative ion source : Proceedings of the 7th international conference on ion sources (1998)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 69 (1998), S. 968-970 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Expression of cusp loss width derived by Bosch and Merlino is applied to JAERI's Kamaboko source. The width is related to the ambipolar diffusion coefficient across the cusp magnetic field. Electron–ion collision is found 1.2–7.4 times larger as compared with electron-neutral collision. Averaged cusp magnetic field in the diffusion coefficient is taken as a parameter in the simulation code for Kamaboko source. When the averaged magnetic field is 48 G, simulation results agree well with JAERI's experiment in a wide range of pressure and arc power variation. The value of 48 G is reasonable from the consideration of confining the equation of ion source plasma. The obtained width is about 10 times the value evaluated by two times ion Larmor radius on the surface of cusp magnet. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1148603
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  • 9
    Electronic Resource
    Electronic Resource
    Importance of Cs adsorption on the cold surface in H− ion source : Papers from the Ninth International Conference on Ion Sources (2002)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 73 (2002), S. 943-945 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A model for the time variation of the Cs coverage on the plasma grid (PG) surface is made and confirmed theoretically. Final coverage is determined by the sum of gaseous and adsorbed Cs on the PG surface. The sum is equal to the Cs not yet adsorbed on the cold surface. The sum decreases on account of the adsorption on the cold surface with time of order of hours. The time of the decrease of the sum is related to the quantity of the seeded Cs. For the case of 600 mg Cs seeding, the sum relaxes to some nonzero value, which gives the optimum coverage on the PG surface. The optimum coverage lasts long. For less than 600 mg Cs seeding the sum relaxes to zero and it makes the coverage go to zero with time of order of hours. The mechanism is shown and an illustrative model calculation is given of the hysteresis in the negative ion current seen when PG temperature is increased and decreased. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1431407
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  • 10
    Electronic Resource
    Electronic Resource
    Statistical modeling of dynamic random access memory data retention characteristics (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 80 (1996), S. 3091-3099 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A statistical model to investigate the distribution of dynamic random access memory data retention times is proposed. The model assumes that the retention time is determined by a junction leakage current generated at carrier traps by a Shockley–Read–Hall process, and that the trap levels are randomly distributed not only among the memory cells but also within a cell. Monte Carlo results based on the model were in excellent agreement with experimental results, which confirmed the validity of the model. An analytical expression of the retention time distribution was also derived, and proved a good approximation near the 50% cumulative probability. Based on the model, variation in the retention time distributions among samples was found to be related to different trap-level distributions at the SiO2/Si interface. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363119
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