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1

Digitale Medien

Effects of ammonium ions on the depolarization-induced and direct activation of the contractile apparatus in mechanically skinned fast-twitch skeletal muscle fibres of the rat (1996)

Stephenson, Gabriela M. M. ; Stephenson, D. George

Springer

Journal of muscle research and cell motility 17 (1996), S. 611-616

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ISSN: 1573-2657

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Medizin

Notizen: Summary Mechanically skinned fibre preparations from the extensor digitorum longus muscle of the rat were used to test whether a rise in myoplasmic [NH4 +] in the range 2–10 mm interferes with the mechanism of excitation-contraction coupling in fast-twitch mammalian muscle. Under our conditions (pH 7.10, Mg2+ 1 mm, temperature 23° C), [NH4 +] up to 10 mm had little effect on the Ca+-activated force and on the peak of the t-system depolarization-induced force response. However, the duration of the depolarization-induced force response was decreased significantly at [NH4 +] ≥2 mm. From these data we conclude that the intracellular accumulation of NH4 + is not likely to play a major role in fatigue. Nevertheless, the build up of NH4 + during fatigue, may have a significant inhibitory effect on the force output by decreasing the duration of the t-system depolarization-induced activation of the contractile apparatus.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00154055

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2

Digitale Medien

Managing workforce diversity: macro and micro level HR implications of network analysis (1996)

Stephenson, Karen ; Lewin, David

Bingley : Emerald

International journal of manpower 17 (1996), S. 168-196

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ISSN: 0143-7720

Quelle: Emerald Fulltext Archive Database 1994-2005

Thema: Wirtschaftswissenschaften

Notizen: Public policy which controls and seeks to correct employment discrimination is now in its fourth decade in the USA. Organizations have made strides in complying with such policies through their hiring practices and in employee development and training programmes. While laws such as the Civil Rights Act and programmes such as EEO and AA have high aims and lofty claims, in practice they miss the mark in organizations. Research indicates that the nature of the work relationship is constrained by both network and hierarchical forms of organization. Suggests that policy is predicated only on the latter and that innovation may lie in the former. Finds that understanding and managing the networks in organizations may be used to augment existing programmes in achieving non-discriminatory or "fair" employment practices.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1108/01437729610127587

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3

Digitale Medien

Coring artifacts and contaminant inventories in lake sediment (1996)

Stephenson, M. ; Klaverkamp, J. ; Motycka, M. ; [weitere]

Springer

Journal of paleolimnology 15 (1996), S. 99-106

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ISSN: 1573-0417

Schlagwort(e): lake sediments ; gravity core ; freeze core ; coring artifacts ; contaminant concentration ; contaminant inventory

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie , Geologie und Paläontologie

Notizen: Abstract Sediments of Lake 382, Experimental Lakes Area, Canada, were sampled at six sites using a 5-cm Wildco KB core sampler (KB), a similar device incorporating a ball check valve (BC), and a 0.2 m by 1.2 m flat-faced aluminum freeze core sampler (FC). Cores were sectioned at 1-cm intervals to a depth of 15 cm. Contaminant (210Pb and 137Cs) concentrations (Bq g-1) were measured by gamma spectroscopy, and inventories (Bq cm-2) were calculated following standard methods. Sediments collected using FC, BC and KB had similar contaminant concentrations, however, cores collected by FC and BC had lower estimated inventories than KB cores. Differences between estimates appear to be caused by differences in the water content (WC) of core material. Laboratory studies confirm that FC sediments have higher WC than tube-cored sediment. We hypothesize that ice crystal formation increases the WC of freeze cores, resulting in lower contaminant inventories. Loss of surficial sediment caused by a ‘bow wave’ may have a similar effect on BC samples. We conclude that KB core gear is appropriate for sampling sediments to measure contaminant concentrations and inventories in recently deposited sediments.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00176992

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4

Digitale Medien

Building-in reliability - implementation and benefits (1996)

Prendergast, James ; Murphy, Eammon ; Stephenson, Malcom

Bingley : Emerald

International journal of quality & reliability management 13 (1996), S. 77-90

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ISSN: 0265-671X

Quelle: Emerald Fulltext Archive Database 1994-2005

Thema: Wirtschaftswissenschaften

Notizen: Argues that in the coming years the present methods of demonstrating reliability will no longer be feasible and alternative methods must be found. Deals with building-in reliability (BIR) and the necessity to change from the standard end-of-line-measurement technique of life test to a more proactive in-line approach, where reliability can be measured by process parameters and reaction time is immediate, resulting in a continuous flow of reliable product to the end user. This approach will not eliminate the use of end-of-line monitoring, but will reduce the amount which needs to be carried out. Suggests that it will only be done to demonstrate that processes are operating to certain maximum failure rates, where the online controls will in fact guarantee that the reliability is much greater than that being demonstrated. Examines the customers' attitude towards reliability, and points out that sharing of data will be essential if the BIR approach is to be successful. Outllines two examples which demonstrate the effectiveness of a BIR program and explains how, if implemented, it can be used to prevent the manufacture of potentially unreliable product.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1108/02656719610118115

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5

Digitale Medien

UV spectroscopy of metal volatilization during thermal plasma processing of waste glass melts (1996)

Wood, Jeffrey W. ; Cortez, Rebecca ; Cahill, David G. ; [weitere]

Springer

Plasma chemistry and plasma processing 16 (1996), S. 449-460

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ISSN: 1572-8986

Schlagwort(e): Spectroscopy ; volatilization ; iron ; nickel ; chromium ; waste vitrification

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie , Maschinenbau , Technik allgemein

Notizen: Abstract Atomic emission spectroscopy (AES) is used to monitor volatilization during waste vitrification with thermal plasmas. Model baste specimens consist of am alumino-silicate clay spiked with 10 wt. % Fe, Ni, or Cr. Specimens are vitrified in processing atmospheres with 0, 8.5, and 17 vol. % oxygen/argon concentrations. Particulate generated from condensation of the volatilized materials is collected following each specimen run and analyzed by energy dispersive X-ray analysis to determine composition. Spectra are collected from the ultraviolet range 240–380 nm in where the presence of metal vapor is readily detected. Correlation between line emission intensities and volatilization rates allows the establishment of provisional detection limits for the volatilization of Ni, Cr, Si, and Fe, of 1 × 103 g/s, 4 × 104 g/s, 2 × 104 g/s, and 5 × 105 g/s, respectively. The results of this investigation support the concept of using AES as an in-situ process monitor for feedback to optimize plasma processing of hazardous metal-containing waste.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF01447155

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6

Digitale Medien

Metal co-injection moulding (1996)

Alcock, J. R. ; Logan, P. M. ; Stephenson, D. J.

Springer

Journal of materials science 15 (1996), S. 2033-2035

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ISSN: 1573-4811

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00278613

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7

Digitale Medien

Effects of pollen selection on progeny vigor in a Cucurbita pepo × C. texana hybrid (1996)

Quesada, M. ; Winsor, J. A. ; Stephenson, A. G.

Springer

Theoretical and applied genetics 92 (1996), S. 885-890

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ISSN: 1432-2242

Schlagwort(e): Key words Microgametophyte selection ; Pollen selection ; Pollen competition ; Cucurbita texana ; Cucurbita pepo

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract We examined the effects of pollen selection for rapid pollen-tube growth on progeny vigor. First, we crossed a wild gourd (Cucurbita texana) to a cultivated zucchini (Cucurbita pepo cv `Black Beauty') to produce an F1 and then an F2 generation. Half of the F1 seeds were produced by depositing small loads of C. texana pollen onto the stigmas of C. pepo. These small pollen loads were insufficient to produce a full complement of seeds and, consequently, both the fast- and the slow-growing pollen tubes were permitted to achieve fertilization. An F2 generation was then produced by depositing small loads of F1 pollen onto stigmas of F1 plants. The F2 seeds resulting from two generations of small pollen loads are termed 'the non-selected line' because there was little or no selection for pollen-tube growth rate on these plants. The other half of the F1 and F2 seeds were produced by depositing large pollen loads (〉10000 pollen grains) onto stigmas and then allowing only the first 1% or so of the pollen tubes that entered the ovary to fertilize the ovules. We did this by excising the styles at the ovary at 12–15 h after pollination. The resulting F2 seeds are termed `the selected line' because they were produced by two generations of selection for only the fastest growing pollen tubes. Small pollen loads from the F2 plants, both the selected and the non-selected lines, were then deposited onto stigmas of different C. pepo flowers, and the vigor of the resulting seeds was compared under greenhouse and field conditions. The results showed that the seeds fertilized by pollen from the selected line had greater vegetative vigor as seedlings and greater flower and fruit production as mature plants than the seeds fertilized by pollen from the non-selected line. This study demonstrates that selection for fast pollen-tube growth (selection on the microgametophyte) leads to a correlated increase in sporophyte (progeny) vigor.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/s001220050207

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8

Digitale Medien

Effects of pollen selection on progeny vigor in a Cucurbita pepo x C. texana hybrid (1996)

Quesada, M. ; Winsor, J. A. ; Stephenson, A. G.

Springer

Theoretical and applied genetics 92 (1996), S. 885-890

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ISSN: 1432-2242

Schlagwort(e): Microgametophyte selection ; Pollen selection ; Pollen competition ; Cucurbita texana ; Cucurbita pepo

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract We examined the effects of pollen selection for rapid pollen-tube growth on progeny vigor. First, we crossed a wild gourd (Cucurbita texana) to a cultivated zucchini (Cucurbita pepo cv ‘Black Beauty’) to produce an F1 and then an F2 generation. Half of the F1 seeds were produced by depositing small loads of C. texana pollen onto the stigmas of C. pepo. These small pollen loads were insufficient to produce a full complement of seeds and, consequently, both the fast- and the slow-growing pollen tubes were permitted to achieve fertilization. An F2 generation was then produced by depositing small loads of F1 pollen onto stigmas of F1 plants. The F2 seeds resulting from two generations of small pollen loads are termed the non-selected line because there was little or no selection for pollen-tube growth rate on these plants. The other half of the F1 and F2 seeds were produced by depositing large pollen loads (〉10 000 pollen grains) onto stigmas and then allowing only the first 1% or so of the pollen tubes that entered the ovary to fertilize the ovules. We did this by excising the styles at the ovary at 12–15 h after pollination. The resulting F2 seeds are termed ‘the selected line’ because they were produced by two generations of selection for only the fastest growing pollen tubes. Small pollen loads from the F2plants, both the selected and the non-selected lines, were then deposited onto stigmas of different C. pepo flowers, and the vigor of the resulting seeds was compared under greenhouse and field conditions. The results showed that the seeds fertilized by pollen from the selected line had greater vegetative vigor as seedlings and greater flower and fruit production as mature plants than the seeds fertilized by pollen from the non-selected line. This study demonstrates that selection for fast pollen-tube growth (selection on the microgametophyte) leads to a correlated increase in sporophyte (progeny) vigor.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00221902

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9

Digitale Medien

Comparison of five media for the axenic culture of Myriophyllum sibiricum Komarov (1996)

Roshon, R. D. ; Stephenson, G. R. ; Horton, R. F.

Springer

Hydrobiologia 340 (1996), S. 17-22

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ISSN: 1573-5117

Schlagwort(e): aquatic plant media ; Myriophyllum sibiricum ; axenic culture ; pesticide bioassay

Quelle: Springer Online Journal Archives 1860-2000

Thema: Biologie

Notizen: Abstract Myriophyllum sibiricum Komarov, an aquatic dicotyledonous macrophyte with a north temperate distribution, was assessed for use in a new bioassay to determine the effect of pesticides, agricultural runoff and municipal waste upon non-target aquatic macrophytes. An axenic culturing system was developed for which an optimal growth medium is required before a bioassay will be reliable. Five media (Murashige and Skoog, Hoagland's, Gaudet's, modified Andrew's, and Hard Water media), commonly used for aquatic plant culturing, were compared to determine the effect on M. sibiricum growth and development. Morphological endpoints for the assay included shoot length, total root length and number, fresh weight and plant area. Membrane integrity, chlorophyll a, chlorophyll b and carotenoid content were the physiological endpoints examined. Based upon these criteria, the modified Andrew's medium at a pH of 5.8, without the addition of a buffer was chosen as a medium which supported rapid and consistent development of M. sibiricum during the two week assay period.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00012728

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10

Digitale Medien

Insider trading during bankruptcy: Do insiders trade on private knowledge? (1996)

Stephenson, Kevin

Springer

International advances in economic research 2 (1996), S. 196-196

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ISSN: 1573-966X

Quelle: Springer Online Journal Archives 1860-2000

Thema: Wirtschaftswissenschaften

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02295064

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