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  • 1
    Electronic Resource
    Electronic Resource
    Conditioning of hydrogenated amorphous carbon thin films for field emission via current stressing (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 347-349 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of electrical current stressing on the field emission characteristics of hydrogenated amorphous carbon (a-C:H) thin films are reported. In these a-C:H films an initial conditioning treatment of the film is often required before the onset of stable emission and only after several voltage cycles do the values of the threshold field tend to converge. By stressing of the film by applying a predetermined current through the film, the initial conditioning treatment can be removed and stable and reproducible emission observed. Retesting of the current stressed films shows that the films remain fully conditioned provided a sufficiently high stress current was initially used. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1339999
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  • 2
    Electronic Resource
    Electronic Resource
    Origin of electric field enhancement in field emission from amorphous carbon thin films (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 2339-2341 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The observation of electron emission from amorphous carbon thin films at low applied electric fields is explained in terms of an enhancement of the field brought about by dielectric inhomogeneities within the film. These inhomogeneities originate from the differences between conductive, spatially localized sp2 C clusters surrounded by a more insulating sp3 matrix. By a more complete understanding of the concentration and distribution of the clusters, a generic model for field emission from amorphous carbon thin films can be developed. Extensions of this model to explain the emission properties of carbon nanotubes and carbon nanocomposite materials are also presented. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1366369
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of sp2 clusters on the field emission properties of amorphous carbon thin films (2000)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 2006-2008 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The influence of the concentration and size of sp2 carbon clusters on the field emission properties of hydrogenated amorphous carbon thin films is investigated. In combination with electron paramagnetic resonance and optical measurements, it is shown that the trend in the threshold field for emission for films deposited under certain conditions can be explained in terms of improvements in the connectivity between sp2 clusters. These clusters are believed to be located near the Fermi level, and the connectivity is primarily determined by the cluster size and concentration, which in turn is determined by the choice of deposition conditions. Details of the appropriate emission mechanisms for different types of deposited carbon films are discussed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1312202
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  • 4
    Electronic Resource
    Electronic Resource
    Vaginal Infections and Prematurity (1987)
    Oxford, UK : Blackwell Publishing Ltd
    Birth 14 (1987), S. 0 
    Details
    ISSN: 1523-536X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: : This is a review of four vaginal and cervical infections that may be associated with prematurity, premature rupture of the membranes, or low birthweight. Urea-plasma urealyticum, group B streptococcus, Chlamydia trachomatis, and anaerobic vaginosis are discussed, along with other data regarding intrauterine infection as a cause of prematurity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1523-536X.1987.tb01460.x
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  • 5
    Electronic Resource
    Electronic Resource
    Silane triols of high stability in aqueous solution (1977)
    [s.l.] : Nature Publishing Group
    Nature 266 (1977), S. 154-156 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The rate of condensation and polymerisation of silicic acid and organo-silanol derivatives in aqueous solution can be reduced by the addition of polar molecules such as ethers, alcohols and amines and of polymers containing similar groups4. The retardation is believed to be due to association ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/266154a0
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  • 6
    Electronic Resource
    Electronic Resource
    Magnesium sulphate salts and the history of water on Mars (2004)
    [s.l.] : Macmillian Magazines Ltd.
    Nature 431 (2004), S. 663-665 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Recent reports of ∼30 wt% of sulphate within saline sediments on Mars—probably occurring in hydrated form—suggest a role for sulphates in accounting for equatorial H2O observed in a global survey by the Odyssey spacecraft. Among salt hydrates likely to be ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/nature02973
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  • 7
    Electronic Resource
    Electronic Resource
    Primary Culture of Mouse Endometrium on Floating Collagen Gels: A Potential in Vitro Model for Implantation (1986)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 476 (1986), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1986.tb20924.x
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  • 8
    Electronic Resource
    Electronic Resource
    Demography of a native strain of the melon fly, Dacus cucurbitae, from Hawaii (1985)
    Springer
    Entomologia experimentalis et applicata 38 (1985), S. 195-199 
    Details
    ISSN: 1570-7458
    Keywords: melon fly ; Dacus cucurbitae ; demography ; life tables ; host studies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Le développement préimaginal et les taux de survie d'une souche sauvage de D. cucurbitae de Hawaí sur six hôtes courants ont été examinés à 25°C. Ces résultats ont été combinés aux informations récoltées sur la survie des adultes, la fécondité et la fertilité pour réaliser des tables de vie. La durée du stade oeuf est légèrement supérieure à un jour pour cette espèce. La durée de développement de l'éclosion de l'oeuf à l'imago et les taux de survie ont été respectivement de 17 à 20 jours et de 35 à 85% suivant les hôtes. La fécondité brute (ponte totale) a été de 1293 oeufs par femelle, tandis qui ‘la fertilité’ (nombre total d'oeufs fertiles pondéré par les taux d'éclosion et de survie des adultes) était de 518 oeufs fertiles par femelle. Le taux d'accroissement (λ) variait de 1,08 à 1,12 suivant l'hôte sur lequel D. cucurbitae a été élevé. La proportion d'adultes dans une distribution en âge stable était d'environ 14% sur tous les hôtes.
    Notes: Abstract Preadult development and survival rates for a wild strain of melon fly in Hawaii were examined when reared on six common hosts at 25°C. These data were combined with information gathered on adult survival, fecundity and fertility in order to construct life tables. The duration of the egg stage was slightly over 1 day for this species. Depending on host, larval-to-adult development and survival rates were 17–20 days and 35–85%, respectively. Gross fecundity (total eggs) was 1293 eggs/♀ while net fertility (total fertile eggs weighted by hatch and adult survival) was 518 fertile eggs/♀. The finite rate of increase (λ) for the species was conditional on the host on which it was reared and ranged from 1.08 to 1.12. The percent of adults in the stable age distribution averaged around 14% over all hosts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00361932
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  • 9
    Electronic Resource
    Electronic Resource
    Reproductive limits and heterogeneity of male twospotted spider mites (1989)
    Springer
    Entomologia experimentalis et applicata 50 (1989), S. 209-214 
    Details
    ISSN: 1570-7458
    Keywords: Demography ; male population biology ; sex ratio ; Tetranychus urticae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé La reproduction est un processus qui nécessite généralement un mâle et une femelle. Cependant la biologie des populations ne s'est traditionnellement intéressée qu'à la contribution des femelles dans ce processus. Un effet de cet accent sur les femelles est que l'activité reproductrice des mâles a été très ignorée. Cet article examine, dans un contexte démographique, l'activité reproductrice des mâles de T. urticae, acarien arrhénotoque et phytophage. Trois séquences de l'activité reproductrice des mâles ont été examinées: 1) la copulation, 2) l'insémination, 3) la reproduction. En moyenne un mâle de 1 jour a copulé 15 fois, inséminé 15 femelles et a eu 336 filles. Pendant les 8 premiers jours, le mâle moyen a inséminé 70 femelles et a eu 1145 filles. Ces résultats suggèrent que le nombre de spermatozoïdes transférés à chaque insémination, plus que le nombre d'inséminations, est le facteur limitant d'une forte contribution du mâle à la reproduction.
    Notes: Abstract This paper determines reproductive limits and variation in performance of male twospotted spider mites Tetranychus urticae Koch when virgin females are provided ad libitum over the first eight days of adult life. Theree phases of male reproduction were studied: copulations, insemination and reproduction. An average one day old male copulated 15 times, inseminated 15 females, and contributed to 336 daughters. All parameters declined with age. The average male inseminated 70 females and contributed to 1145 daughters in the first days. Variability between males was small for all parameters considered. These data suggest that the number of sperm transferred at each insemination, rather than the number of inseminations, is the limiting step to higher male reproductive output.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00341169
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  • 10
    Electronic Resource
    Electronic Resource
    Life history response of female Mediterranean fruit flies, Ceratitis capitata, to periods of host deprivation (1986)
    Springer
    Entomologia experimentalis et applicata 42 (1986), S. 159-167 
    Details
    ISSN: 1570-7458
    Keywords: Mediterranean fruit fly ; Ceratitis capitata ; host deprivation ; senescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Les femelles de C. capitata ont été privées d'hôtes suivant 4 modalités pendant 3 durées (33, 50 et 67% de leur vie) par période de 24 heures. Les modalités se répartissaient de la privation pendant 8 jours après l'éclosion jusqu'à 1 jour sur 3. La survie a été notée chaque jour et la ponte pour tous les jours où il y avait des hôtes. L'effect direct de l'absence d'hôte est d'empêcher la femelle de pondre. Ceci interrompt leur cycle de ponte et réduit leur activité reproductrice totale. Un effort reproductif réduit des femelles jeunes augmente la survie (jusqu'à 2 fois) et la ponte quotidienne (jusqu'à 8 fois) chez les femelles plus âgées. Ainsi, l'effet à long terme de la privation d'hôtes est d'ajourner la sénescence. Les implications de ces observations sur la sénescence de C. capitata sont discutées quant à: (1) la réduction des taux d'extinction des populations pendant les périodes de rareté d'hôtes; et: (2) les stratégies d'obtention de pontes dan les élevages de masse de C. capitata.
    Notes: Abstract Female medflies were subjected to four different patterns of host deprivation at each of three levels for a 24-day period. Treatments ranged from host absence 8 days post-eclosion to host absence 2 out of 3 days. Survival was recorded daily and egg production was recorded on the days in which hosts were present. The direct effect of host deprivation is to deny females the opportunity to oviposit. This disrupts their reproductive cycle and reduces their overall reproductive effort. Reduced reproductive effort at young ages increases survival (up to 2-fold) and daily reproduction (up to 8-fold) at older ages. Therefore, the long term effect of host deprivation is to postpone senescence. The implications of these findings regarding medfly sensescence are discussed in relation to: (i) reduction in population extinction rates during periods of host scarcity and (ii) egging strategies in medfly mass-rearing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00343543
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