ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Tree leaf control on low flow water quality in a small Virginia stream (1968)

Slack, K. V. ; Feltz, H. R.

s.l. : American Chemical Society

Environmental science & technology 2 (1968), S. 126-131

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ISSN: 1520-5851

Source: ACS Legacy Archives

Topics: Chemistry and Pharmacology , Energy, Environment Protection, Nuclear Power Engineering

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1021/es60014a005

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2

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EFFECTS OF SPATIAL ORIENTATION OF MULTIPLE PLATE ARTIFICIAL SUBSTRATES ON INVERTEBRATE COLONIZATION (1988)

Slack, K. V. ; Ferreira, R. F. ; Averert, R. C. ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Journal of the American Water Resources Association 24 (1988), S. 0

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ISSN: 1752-1688

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Architecture, Civil Engineering, Surveying , Geography

Notes: : Jumbo multiple plate samplers were suspended in a river at 0.3 and 1 m depth in one of three orientations: interplate spaces closed to downwelling light and open to flow, open to light and flow, or open to light and closed to flow. Mean numbers of colonizing taxa and individuals were not significantly different among orientations after eight weeks of submergence. All variables tested decreased significantly with depth. Mean number of taxa, number of individuals (1 m only), and insect diversity decreased between samplings at four and eight weeks for samplers that were closed to light and open to flow. All orientations, depths, and durations had one-half to two-thirds of the total taxa. Colonization was affected by location in the river and position on sampler suspension equipment. The results indicate lack of orientation effects on colonization or high variability that obscured such effects. The sampler suspension equipment possibly increased among-sampler variability by forming artificial snag habitats, and interplate light and flow conditions at different orientations may not have been sufficiently distinct to elicit different biological responses. Individual samplers provided diverse microhabitats regardless of orientation, but it would be prudent to include orientation among the variables considered in use of multiple plate samplers.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1752-1688.1988.tb00929.x

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3

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Leaf number as a criterion for determining defoliation time for Lolium perenne, 1. Effect of water-soluble carbohydrates and senescence (1994)

FULKERSON, W. J. ; SLACK, K.

Oxford, UK : Blackwell Publishing Ltd

Grass and forage science 49 (1994), S. 0

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ISSN: 1365-2494

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: This study sought to define the optimum defoliation interval for Lolium perenne, with the maximum interval being determined by the onset of senescence, as reflected by the number of fully expanded leaves, and the minimum interval set by the replenishment of water-soluble carbohydrates (WSCs).In a glasshouse set at 13°C/23°C night/day temperature and at a plant spacing of 94 m−2 (3290 tillers m−2), the accumulation of dry matter against leaf number and days was exponential to the four-leaf stage of the regrowth cycle. Senescence commenced at the 3·5-leaf stage.WSCs in roots, stubble and leaf showed a very significant linear relationship with leaf number. Levels of WSCs in leaves were restored to predefoliation values by the one-leaf stage, after which WSCs accumulated preferentially in the stubble, rising to 22% at the four-leaf stage.Regrowth after 6 d was significantly greater for plants defoliated at the three-leaf stage than at the one-leaf stage, but this difference disappeared at the end of the regrowth cycle. This questions the importance of WSCs in determining the yield of ryegrass under normal rotational grazing management.Regrowth at 6 d was related positively to stubble WSCs (r2= 0·66) and to stubble DM per tiller(r2=0·71)

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1365-2494.1994.tb02013.x

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4

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Leaf number as a criterion for determining defoliation time for Lolium perenne: 2. Effect of defoliation frequency and height (1995)

FULKERSON, W.J. ; SLACK, K.

Oxford, UK : Blackwell Publishing Ltd

Grass and forage science 50 (1995), S. 0

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ISSN: 1365-2494

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: The object of this study was to determine the importance of frequency and height of defoliation on regrowth potential of Lolium perenne. Defoliation interval was based on stage of the regrowth cycle, as indicated by leaves per tiller.Simulated swards of Lolium perenne cv Yatsyn were grown as individual plants in a glasshouse kept at a day/night temperature of 25°C/15°C.Treatments imposed were defoliation at 2, 5 or 12 cm residual height, and low and high water soluble carbohydrate (WSC) level obtained by varying defoliation interval, i.e. defoliating at the 1-leaf or 3-leaf stage of the regrowth cycle. Regrowth after frequent short defoliations was only 65% of the less frequently defoliated plants taken over the full regrowth cycle. This was associated with a lower stubble WSC content (2·15 vs 17·5% in stubble) and a twenty-seven-fold difference in the amount of WSC in the stubble per plant. This difference in total WSC was a combined effect of more and heavier tillers and higher WSC content in stubble of plants defoliated less frequently at the end of the regrowth cycle. The regrowth of plants with WSC levels depleted by frequent defoliation when defoliated at 2 cm was significantly below that of those defoliated at 5 and 12 cm.The results indicate the desirability of defoliating plants at the 3-leaf stage of the regrowth cycle. This not only allows the full regrowth potential to be expressed in that growth cycle, but also in the next cycle, by allowing the replenishment of WSC reserves and optimizing tiller status. The potential to regrow appears then to be based more on the total amount of WSC than the proportion of WSC in stubble.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1365-2494.1995.tb02289.x

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5

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BENTHIC INVERTEBRATES IN A NORTH-FLOWING STREAM AND A SOUTH-FLOWING STREAM, BROOKS RANGE, ALASKA (1979)

Slack, K. V. ; Nauman, J. W. ; Tilley, L.J.

Oxford, UK : Blackwell Publishing Ltd

Journal of the American Water Resources Association 15 (1979), S. 0

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ISSN: 1752-1688

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Architecture, Civil Engineering, Surveying , Geography

Notes: : Benthic invertebrate faunas were compared to two fifth-order streams, the Atigun River flowing northward and the Dietrich River flowing southward. Sixty-eight taxa were collected, forty-nine from each stream. Aquatic insects comprised 88% of the taxa and 97% of the individuals from the Dietrich River and 73% of the taxa and 97% of the individuals from the Atigun River. Diptera, especially Chironomidae, were most abundant. Plecoptera, Ephemeroptera, Oligochaeta, Acarina, and Collembola were significant. In both streams the headwaters were dominated by the subfamily Diamesinae which was replaced by Orthocladiinae downstream. Diversity seemed to increase with stream order. Cluster analysis showed a high degree of resemblance between the benthic faunas of the rivers. Faunal resemblance decreased with increasing distance between stations, both within and between the streams. Although some taxa may occur in only one stream, the evidence for faunal resemblance is stronger than for faunal differences. Other studies have shown that differences in total radiation associated with valley aspect affect local climate, hydrology, and distribution of terrestrial plants and animals. However, the benthic faunas of Atigun and Dietrich Rivers were remarkably similar. Factors which operate independently of aspect, possibly freezing solid in winter, may control the occurrence of species in these streams.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1752-1688.1979.tb00293.x

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6

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Mesh-size effects on drift sample composition as determined with a triple net sampler (1991)

Slack, K. V. ; Tilley, L. J. ; Kennelly, S. S.

Springer

Hydrobiologia 209 (1991), S. 215-226

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ISSN: 1573-5117

Keywords: Invertebrate drift ; drift sampling ; mesh size effects

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Nested nets of three different mesh apertures were used to study mesh-size effects on drift collected in a small mountain stream. The innermost, middle, and outermost nets had, respectively, 425 µm, 209 µm and 106 µm openings, a design that reduced clogging while partitioning collections into three size groups. The open area of mesh in each net, from largest to smallest mesh opening, was 3.7, 5.7 and 8.0 times the area of the net mouth. Volumes of filtered water were determined with a flowmeter. The results are expressed as (1) drift retained by each net, (2) drift that would have been collected by a single net of given mesh size, and (3) the percentage of total drift (the sum of the catches from all three nets) that passed through the 425 µm and 209 µm nets. During a two day period in August 1986, Chironomidae larvae were dominant numerically in all 209 µm and 106 µm samples and midday 425 µm samples. Large drifters (Ephemerellidae) occurred only in 425 µm or 209 µm nets, but the general pattern was an increase in abundance and number of taxa with decreasing mesh size. Relatively more individuals occurred in the larger mesh nets at night than during the day. The two larger mesh sizes retained 70% of the total sediment/detritus in the drift collections, and this decreased the rate of clogging of the 106 µm net. If an objective of a sampling program is to compare drift density or drift rate between areas or sampling dates, the same mesh size should be used for all sample collection and processing. The mesh aperture used for drift collection should retain all species and life stages of significance in a study. The nested net design enables an investigator to test the adequacy of drift samples.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00015344

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7

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Coating of a semi-conducting polymer for use in electrorheological fluids (2001)

Akhavan, J ; Slack, K

Elsevier

In: Synthetic Metals. 2001; 124(2-3): 363-371. Published 2001 Oct 01. doi: 10.1016/s0379-6779(01)00375-7.

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Publication Date: 2001-10-01

Print ISSN: 0379-6779

Electronic ISSN: 1879-3290

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Published by Elsevier

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Ionospheric structures correlated with Anatolian surface features (2011)

T. W. Garner, C. M. Slack, K. Mehta, A. Scholze and A. M. Mahrous

Wiley

In: Radio Science

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Publication Date: 2011-08-16

Description: A UHF/VHF beacon receiver located in Helwan, Egypt, frequently observes structures in ΔTEC/Δt measurements (where TEC is total electron count), where the F region (300 km) intercept of the radio rays crosses the steep topographic gradients associated with the Anatolian Plateau. There are three classes of structures: bumps, ripples and waves. A bump is defines as a single spatial ΔTEC/Δt peak with a peak-to-trough amplitude of at least 0.01 TECU/s (1 TEC unit (TECU) = 1016 electrons/m2) that is at least 1° wide in F region latitude. A ripple is a bump with smaller structures on either side of the central bump. Finally, waves have amplitudes ≥0.01 TECU/s with several roughly equal peaks. These features were observed repeatedly in a number passes from 31 August to 30 November 2008. Over half of passes had either a bump (34.6%), a ripple (18.2%) or a wave (6.3%). Most of these structures occur near areas with large orographic gradients. The prevailing surface wind blows across the mountains when bumps and ripples are observed. These correlations suggest that the local ionosphere is affected by the ground topography, most likely through the orographic lifting and the associated gravity waves.

Print ISSN: 0048-6604

Electronic ISSN: 1944-799X

Topics: Geosciences , Physics