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Showing papers by "University of Maine published in 1986"


Journal ArticleDOI
01 Nov 1986-Nature
TL;DR: In this article, a two-component equilibrium model involving a solid-phase humic adsorbent and an aluminium trihydroxide mineral phase is proposed to account for the spatial and temporal variability in aqueous aluminium chemistry.
Abstract: Aluminium is a pH-sensitive element that can cause acute toxicity symptoms in some organisms at aqueous activities of 10 µM or less1–3. Scientists working on agricultural systems have long been concerned with the deleterious effects of aluminium on crop roots4,5. More recently, environmental scientists have reported a potentially harmful biogeochemical link between acidic deposition onto forest soils and aluminium toxicity in forest and aquatic communities of northeastern North America and northern Europe6–8. Because of this general interest in aluminium toxicity as an environmental threat, there have been renewed efforts to model the chemistry and transport of aqueous aluminium in soils and surface waters. Here we propose that much of the spatial and temporal variability in aqueous aluminium chemistry can be accounted for by a two-component equilibrium model involving a solid-phase humic adsorbent and an aluminium trihydroxide mineral phase. Inputs for the model are solution pH, copper-extractable organic aluminium and the titratable carboxyl content of soil humus.

316 citations


Journal ArticleDOI
TL;DR: This review describes several distinct lines of evidence which converge on the general hypothesis that circadian timing systems consist of multiple circadian oscillators, coordinated by both hierarchical and non-hierarchical coupling relationships.

175 citations


Journal ArticleDOI
TL;DR: The radiometric results on the Anakapalle rocks are the first evidence in South India for sapphirine formation during the late Proterozoic; other South Indian localities appear to be Archaean in age.

158 citations


Journal ArticleDOI
01 Oct 1986-Nature
TL;DR: In this paper, the authors present an alternative model, in which low-P/high-T metamorphism (prograde reactions at pressures near or below the Al2SiO5 triple point) results from contact effects near sill-like igneous intrusions at intermediate crustal levels.
Abstract: Wickham and Oxburgh1 recently proposed that low-pressure/high-temperature (low-P/high-T) metamorphism in the eastern Pyrenees, and possibly all low-P/high-T metamorphic belts, resulted from anomalously high mantle heat flow brought about by rifting. Their model is largely constrained by the presence of nearby synmetamorphic rift-related sedimentary rocks and the interpretation that the migmatites and granites are the product of in situ melting in the presence of an anomalously steep geotherm. Here we present an alternative model, in which low-P/high-T metamorphism (pro-grade reactions at pressures near or below the Al2SiO5 triple point) results from contact effects near sill-like igneous intrusions at intermediate crustal levels. Low-P/high-T conditions can be achieved through this process in regions of continent–continent collision with normal mantle heat flux as well as in zones of extension. Our model is based on studies of the low-P/high-T metamorphic terrane in the New England Appalachians.

156 citations


Journal ArticleDOI
TL;DR: Carrots, beet greens, spinach, swiss chard and sweet potatoes had the most vitamin A activity and beta-Carotene was the most prevalent carotenoid.
Abstract: A study was conducted to determine alpha- and beta-carotene and beta-cryptoxanthin in twenty-two fruits and vegetables. Foods were obtained from wholesale distributors from five locations throughout the United States (Los Angeles, Dallas, Chicago, Miami, and Boston) three times during a year (November, March, and July). Mean vitamin A activity in retinol equivalents (RE) of each food along with average values for the individual carotenoids (μg/100g) are given. beta-Carotene was the most prevalent carotenoid. Carrots, beet greens, spinach, swiss chard and sweet potatoes had the most vitamin A activity. Analysis of variance indicated that there were no significant differences among either locations or time of analysis. A comparison was made between the new values and the ones listed in USDA Handbook No. 8 and revised Handbook No. 8–9. There were differences between the old and new values in 14 of the 22 fruits and vegetables analyzed.

151 citations


Journal ArticleDOI
Gary M. King1
TL;DR: Glycoside derivatives of 4-methylumbelliferone (MUF) provided a convenlent tool for initial analyses of the dynamics and controls of polymer hydrolysis in marine sediments.
Abstract: Glycoside derivatives of 4-methylumbelliferone (MUF) were used to characterize the polysaccharidase enzyme systems present in sediments from an intertidal mud flat. The formation of highly fluorescent MUF on hydrolysis of the various glycosides was determined at low substrate concentrations ( 5 min). The hydrolysis of MUF-β-d-glucose in sediments from depth intervals of 0 to 2 cm was insensitive to the presence of oxygen, dissolved sulfide, and iron; magnesium and calcium were stimulatory, however. A pronounced temperature optimum was observed at 40°C, a salinity optimum at 30‰, and a pH optimum at 8.5. Rates of hydrolysis were completely inhibited by the addition of mercuric chloride and sodium azide, but only partially inhibited by toluene and the specific β-glucosidase inhibitor δ-1,5-gluconolactone. The response to δ-1,5-gluconolactone suggested that about 50% of the observed hydrolysis of MUF-β-d-glucoside was due to exo- and endoglucanases. A wide variety of hydrolytic activities was observed, with at least some nonspecificity occurring in the case of MUF-β-d-fucoside. Depth profiles indicated maximal activity in surface sediments with a rapid decline below 2 cm. MUF-glycosides provided a convenlent tool for initial analyses of the dynamics and controls of polymer hydrolysis in marine sediments.

146 citations


Book ChapterDOI
TL;DR: The chapter considers several aspects of this phenomenon as the species involved, factors associated with its induction as well as those influencing a resumption of development, implications of the phenomenon for understanding the epidemiology of these conditions, and its adaptive and population regulatory significance.
Abstract: Publisher Summary This chapter reviews the role of hypobiosis in the biology of nematodes. Successful transfer from an infected host to a susceptible one represents a most important achievement in the parasitic way of life. Any developmental adaptation that serves to facilitate this process is, therefore, extremely important in the epidemiology of these infections. Hypobiosis or facultative arrested development represents such an adaptation which, by facilitating the persistence of the larval forms for prolonged periods in the host, enables the parasite to capitalize on optimal opportunities for transfer. The phenomenon appears to be widespread among parasitic organisms. The chapter considers several aspects of this phenomenon as the species involved, factors associated with its induction as well as those influencing a resumption of development, implications of the phenomenon for understanding the epidemiology of these conditions, and its adaptive and population regulatory significance. Host resistance causes the arrested development and that resumption of development is a result of the relaxation of immunity. It is considered to be a host-regulated phenomenon that served to limit the size and pathogenicity of the population of worms, which is accumulating during the season of increasing larval availability. The chapter describes the types of hypobiosis, which include immune-mediated arrest and seasonally induced arrest.

133 citations


Book ChapterDOI
TL;DR: A view consistent with the present evidence is to regard the Turbellaria (and hence the Platyhelminthes) as polyphyletic, consisting of three separate and unrelatable groups.
Abstract: Within the last two decades, syntheses of both light-microscopic and ultrastructural characters have shown that there are three well-defined monophyletic groups within the Platyhelminthes: 1) the Catenulidale, 2) the Nemertodermatida-Acoela, and 3) the Haplopharyngida-Macrostomida-Polycladida-Neoophora (+ parasitic platyhelminth classes). However, the relationships among these three groups are problematic. The possible apomorphies that would unite them are either not true homologues (i.e. frontal organ), are mutually conflicting (i.e. 9+1 axoneme in spermatozoa vs. biflagellate spermatozoa, epidermal ciliary rootlet structure, and protonephridia), or are unrooted with any outgroup and hence untestable or uncertain as apomorphies (pro- tonephridia, mode of epidermal replacement, absence of accessory centrioles on cilia). The chief obstacle to deciphering the relationships of these groups is the lack of information on them; presently available information is insufficient to test potential synapomorphies and insufficient also to allow agreement upon a narrowly defined outgroup for the Turbellaria.

124 citations


Journal ArticleDOI
TL;DR: In this paper, the authors examined some of the mechanisms contributing to aggregation behavior by experimentally manipulating sea urchins, purported predators and food during autumn 1983 and spring 1984 both in the laboratory and field.
Abstract: Defensive aggregation by Strongylocentrotus droebachiensis has been invoked as the fulcrum for the transformation of macroalgal beds into coralline barrens in the northwest Atlantic. We critically examined some of the mechanisms contributing to aggregation behavior by experimentally manipulating sea urchins, purported predators and food during autumn 1983 and spring 1984 both in the laboratory and field. We utilized several approaches to examine a range of sea urchin responses to the presence of food, tethered predators, caged predators, crushed con-specifics in the field and predators in laboratory tanks. Some of the field cages had the property of allowing free passage to sea urchins while retaining lobsters; this allowed distinctions to be made between artifacts caused by cage walls or topographic barriers and unrestricted behavioral responses of sea urchins. The results falsified the hypothesis that aggregations of S. droebachiensis are elicited by predators. Except in the presence of algae, sea urchins always avoided decapod predators (but not sea stars) and fled from the vicinity of injured conspecifics. However, avoidance behavior was subordinate to feeding responses, demonstrated by mass migrations of sea urchins into cages (with lobsters) to feed on algae. We reaffirmed by observation and manipulation previous studies which showed that sea urchins aggregate only in the presence of food. Two types of sea urchin groupings were delineated: (1) surficial two dimensional associations, often caused by topographic or other features which inhibited dispersal and (2) cohesive three-dimensional aggregations induced by food.

123 citations


Journal ArticleDOI
Gary M. King1
18 Sep 1986-Nature
TL;DR: It is suggested that secretion of DBP inhibits the aerobic microbial degradation of the burrow-wall mucous lining or alters local biogeochemistry, suggesting that bromophenols may be targeted against higher organisms with which S. kowalewskii competes as well as against microorganisms.
Abstract: Allelochemicals, a class of organic compounds, affect succession, competition, predation and other interactions between organisms1–3. Bromophenols, a member of this class, are found in marine algae and invertebrates, particularly annelids, phoronids and hemi-chordates4,5. Bromophenols are toxins with bacteriocidal properties6–9. Here I report inhibition of microbial activity in marine sediments by the common bromophenol, 2,4-dibromophenol (DBP), from the hemichordate Saccoglossus kowalewskii and demonstrate that anaerobic microbial metabolism in sediments is relatively unaffected by DBP whereas aerobic metabolism is particularly sensitive. These data, together with observations of the distributions of DBP and burrow-wall chemistry, suggest that secretion of DBP inhibits the aerobic microbial degradation of the burrow-wall mucous lining or alters local biogeochemistry. Thus, bromophenols may be targeted against higher organisms with which S. kowalewskii competes as well as against microorganisms.

118 citations


Journal ArticleDOI
01 Sep 1986-Botany
TL;DR: In this paper, the changing character of vegetation and the effects of disturbance on vegetation are inferred from pollen, plant macrofossils, charcoal, and microlepidopteran larvel head capsules in sediment core.
Abstract: The changing character of vegetation and the effects of disturbance on vegetation are inferred from pollen, plant macrofossils, charcoal, and microlepidopteran larvel head capsules in sediment core...

Journal ArticleDOI
TL;DR: Information and support by professionals, partners and/or fellow patients are related to positive rehabilitation outcomes such as the acquisition of speech, increases in constructive social functioning and decreases in depression.
Abstract: This study is a systematic analysis of the literature on psychosocial aspects in head and neck cancer patients. Patients with head and neck cancer experience a variety of physical as well as psychosocial problems. Physical problems include swallowing or chewing, speech and physical appearance. Psychosocial problems include anxiety, depression, loss of self-esteem and uncertainty about the future. Because of these problems, isolation from friends typically occurs, re-employment is difficult, and there are social and sexual tensions within families. Information and support by professionals, partners and/or fellow patients are related to positive rehabilitation outcomes such as the acquisition of speech, increases in constructive social functioning and decreases in depression.

Journal ArticleDOI
TL;DR: In this paper, the authors used 14C dates and amino acid racemization estimated (AARE) ages, borehole records and stratigraphic sections, shallow seismic profiles, and biostratigraphic analyses obtained since publication of summaries by Schafer and Hartshorn (1965), Muller (1965, and Pratt and Schlee (1969).

Journal ArticleDOI
TL;DR: Recently, Broecker et al. as mentioned in this paper showed that sea level is a major control of the areal extent of grounded portions of the Antarctic Ice Sheet, thus fitting the concept of a globally interlocked ice-sheet system.

Journal ArticleDOI
TL;DR: Resting salivation rate and volume produced while resting were greater at wk 8 than wk 4 of lactation even when corrected to constant dry matter intake, indicating that adaptation to diet postpartum involved increased basal resting salivation rates.

Journal ArticleDOI
TL;DR: In this paper, the effects of rootstock on mid-season water relations, under orchard conditions of non-limiting soil moisture, were determined for bearing ‘Empire’ apple trees (Malus domestica Borkh.) on the clonal rootstocks M9, M26, M7, MM106, and MM104 (most to least dwarfing) in their sixth and seventh growing seasons.
Abstract: The effects of rootstock on mid-season water relations, under orchard conditions of non-limiting soil moisture, were determined for bearing ‘Empire’ apple trees (Malus domestica Borkh.) on the clonal rootstocks M9, M26, M7, MM106, and MM104 (most to least dwarfing) in their sixth and seventh growing seasons. Stem water potentials (ψstem) of trees on M9 and M26 were more negative at midday, under warm, sunny conditions, than were the trees on the other three rootstocks. However, change in ψstem per change in stem distance through the canopy (water potential gradient) did not vary among rootstocks at midday. There was no rootstock effect on diurnal variation in transpiration or stomatal conductance. Differences in water storage capacitance, relative to tree size, were determined in a separate study but did not account for the differences observed in ψstem. Calculated hydraulic conductivities of xylem water transport suggest that rootstocks differ in their ability to conduct water to the scion, but hydraulic conductivity of the scion was not affected by rootstock. Root-stock differences in hydraulic conductivity were not accounted for by differences in tree size.

Journal ArticleDOI
TL;DR: The discovery of a unique organic deposit in a dry cave on the Colorado Plateau, southern Utah, permits the first comparison of the physical characteristics and the diet of the extinct mammoths of the arid Southwest, North America, with that of mammoths from Siberia and northern China, the only other known locations of such remains as mentioned in this paper.

Journal ArticleDOI
TL;DR: Donnees sur l'adsorption de N 2 sur Fe(III) et sur un nouvel effet observe lors de la coadsor adaptation de potassium, a 74 K, qui augmente fortement le coefficient de collage de N2 -α 1.
Abstract: The vibrational and thermal-desorption spectra of the terminal and $\ensuremath{\pi}$-bonded adsorption states of ${\mathrm{N}}_{2}$ on clean and potassium-promoted Fe(111) at 74 K are reported. Submonolayer precoverages of potassium dramatically enhance the sticking coefficient of ${\ensuremath{\alpha}}_{1}\ensuremath{-}{\mathrm{N}}_{2}$, the $\ensuremath{\pi}$-bonded precursor to dissociation. As potassium promotion of surface reactions has been previously attributed to bond weakening in the dissociation precursor, an increase of the precursor population, with no evident bond weakening, is an important new result.

Journal ArticleDOI
TL;DR: It is suggested that the impairment of immunity to helminth infection seen in reproductive ewes may be more specific than was previously envisaged.


Journal ArticleDOI
TL;DR: In this article, the nitrogen budget of the northern Adriatic, one of the most productive subregions in the Mediterranean area, was estimated from data sets collected since 1966 and from results reported in the literature.

Journal ArticleDOI
TL;DR: In this article, the authors reexamined this coralline flora by comparing field and museum collections with type material in order to revise the taxonomy to conform with current concepts and provide new, species specific, ecological data.
Abstract: Encrusting coralline algae are a major component of the rocky intertidal and shallow subtidal zones of the boreal northeastern Pacific (the region from northern California to southeast Alaska). We reexamined this coralline flora by comparing field and museum collections with type material in order to revise the taxonomy to conform with current concepts and to provide new, species specific, ecological data. Of the eight species previously recognized for this region, only Pseudolithophyllum neofarlowii, and Lithothamnion (formerly Lithothamnium) phymatodeum were correctly placed as to genus. Phymatolithon muricatum and Mesophyllum whidbeyense are referred here to the genus Pseudolithophyllum. Lithothamnion pacificum is merged into L. phymatodeum and Lithophyllum lichenare is merged into Pseudolithophyllum muricatum. Lithothamnion californicum and Hydrolithon decipiens were shown not to occur in the study area. Plants in this study area formerly identified as H. decipiens were originally and correct...

Journal ArticleDOI
W. E. Zamer1
TL;DR: Higher growth rates in H anemones, which are supported by higher prey-capture rates, result in attainment of minimum body size for reproduction in a relatively short period of time despite reduction in time available for feeding, thus improving relative fitness of theseAnemones in the upper intertidal zone.
Abstract: Energy budgets were calculated for individuals of the sea anemone Anthopleura elegantissima (Brandt), collected in 1981 and 1982 from Bodega Harbor, California, USA. Rates of ammonium excretion were measured in high-and low-intertidal, symbiotic and aposymbiotic sea anemones within 24 h of collection. Among symbiotic and aposymbiotic individuals, no differences in excretion rate were found on the basis of intertidal height. However, rates of ammonium excretion in aposymbiotic anemones (2.14 μmol NH + 4 g-1 h-1) were significantly higher than in symbiotic ones (0.288 μmol NH + 4 g-1 h-1). Rates of excretion were used with estimated rates of oxygen uptake to calculate nitrogen quotients (NQ). NQ and RQ values from the literature were used to calculate an oxyenthalpic equivalent [501 kJ (mol O2)-1 for R+U], and mass proportions of protein (54%), carbohydrate (44%) and lipid (2%) catabolized during routine metabolism in this species 24 h after feeding. Integrated energy budgets of these experimental anemones were calculated from data on ingestion, absorption and growth, and estimates of translocated energy from the symbiotic algae. Contribution of zooxanthellae to animal respiration based on translocation=90% and RQ=0.97 are 41 and 79% in high-and low-intertidal anemones, respectively. Calculated scope for growth is greater than directly measured growth in both high-and low-intertidal individuals. The deficit, estimated as 30% of assimilated energy in high-intertidal anemones, is attributed to unmeasured costs (specific dynamic effect) or production (mucus). Low-intertidal anemones lost mass during the experiment, implying that the magnitude of the deficit was greater in these anemones than in upper intertidal individuals. Anemones from both shore levels lost zooxanthellae during the experiment, which contributed to energy loss since the contribution of the zooxanthellae is greater in low-intertidal anemones. Scope for growth is preserved in high-intertidal anemones (29% of assimilated energy) because metabolic demands are lower due to aerial exposure, and prey capture rate is higher compared to lowshore anemones. Although possibly underestimated, lower scope for growth in low-shore anemones may result from continuous feeding and digestion processes that are less efficient than those of periodically feeding high-intertidal anemones.

Journal ArticleDOI
TL;DR: The Jakobshavns effect as mentioned in this paper is a group of positive feedback mechanisms that allow the Greenland Ice Sheet to pull ice out at a rate exceeding 7 km/a across a floating terminus 800 m thick and 6 km wide.
Abstract: The Jakobshavns Effect may have been a significant factor in hastening the collapse of palaeo ice sheets with the advent of climatic warming after 18,000 years ago and may precipitate partial collapse of the present-day Greenland and Antarctic Ice Sheets following CO2-induced climatic warming in the decades ahead. The Jakobshavns Effect is observed today on Jakobshavns Glacier, which is located at 69°10′N on the west coast of Greenland. The Jakobshavns Effect is a group of positive feedback mechanisms which allow Jakobshavns Glacier to literally pull ice out of the Greenland Ice Sheet at a rate exceeding 7 km/a across a floating terminus 800 m thick and 6 km wide. The pulling power results from an imbalance of horizontal hydrostatic forces in ice and water columns at the grounding line of the floating terminus. Positive feedback mechanisms that sustain the rapid ice discharge rate are ubiquitous surface crevassing, high summer rates of surface melting, extending creep flow, progressive basal uncoupling, progressive lateral uncoupling, and rapid iceberg calving.


Book ChapterDOI
TL;DR: For example, the accumulation rates of Pb in lake sediments from profundal area cores in the Adirondack Mountains of New York and northern New England have been investigated in this paper.
Abstract: Inter-lake variation in accumulation rates of energy-related elements is a function of gross sedimentation rate (sediment focusing), position on pollution gradients, and water chemistry Accumulation rates of Pb in lake sediments from profundal area cores in the Adirondack Mountains of New York and northern New England2range from 01 to 02 ug/cm2 /y (pre-1800 AD) to as much as 2 ug/cm2/y (recent sediment) Rates increase from the late 1800’s to nearly the present, in parallel Accumulation) rates for V remain at background values which range up to 05 ug/cm2/y and increase 5 to 10 x background in Adirondack Mountain lakes Chronically acidic lakes have a subsurface maximum Of these three metals, only Pb has elevated deposition rates in high elevation lakes in the Rocky Mountains of Colorado Mining activity is believed responsible for the implied air polIution there

Journal ArticleDOI
TL;DR: The pollination process in loblolly pine has been examined over several years, both in the field (seed orchards) and experimentally on greenhouse-grown material.
Abstract: The pollination process in loblolly pine has been examined over several years, both in the field (seed orchards) and experimentally on greenhouse-grown material. Female strobili are receptive to pollination for periods of a wk or more. Initially, background pollen from outside the seed orchard is the main source of pollen but as peak receptivity approaches, pollen from the stand itself predominates especially in older orchards. Consequently, strobili can receive pollen both from outside the orchard as well as from within. The pollen lands on the micropylar horns where it is transferred through the micropyle onto the nucellus by either rainfall or the pollen drop, whichever comes first. Since the pollen drop does not occur until the latter part of the receptive period, rainfall is the most likely transfer agent and pollen flotation is vital if rain occurs. Early arriving pollen does not appear to have an advantage over later arriving pollen for uptake onto the nucellus, even if rain follows the first pollination immediately. Therefore, total pollination of the strobilus can result from both distant and nearby pollen sources.

Journal ArticleDOI
TL;DR: In this paper, a model for direct Auger neutralization of low energy ions near metal surfaces is outlined, and used to calculate the dependence of the transition rates for the H(ls)-Au and H(l)-Al interactions on ion-surface separation.


Journal ArticleDOI
TL;DR: In this paper, the probability of charge capture via the direct Auger process to slow ions scattering from simple metals is investigated. But the results are sensitively dependent on the surface electron density profile and atomic wavefunction distortion in the near surface region.