bluuebunny/crossref_metadata_2025 huggingface dataset:
Voltage-dependent Dynamic FRET Signals from the Transverse Tubules in Mammalian Skeletal Muscle Fibers
Authors: DiFranco Marino , Capote Joana , Quiñonez Marbella , Vergara Julio L.
Published: November 2007

Two hybrid voltage-sensing systems based on fluorescence resonance energy transfer (FRET) were used to record membrane potential changes in the transverse tubular system (TTS) and surface membranes of adult mice skeletal muscle fibers. Farnesylated EGFP or ECFP (EGFP-F and ECFP-F) were used as immobile FRET donors, and either non-fluorescent (dipicrylamine [DPA]) or fluorescent (oxonol dye DiBAC4(5)) lipophilic anions were used as mobile energy acceptors. Flexor digitorum brevis (FDB) muscles were transfected by in vivo electroporation with pEGFP-F and pECFP-F. Farnesylated fluorescent proteins were efficiently expressed in the TTS and surface membranes. Voltage-dependent optical signals resulting from resonance energy transfer from fluorescent proteins to DPA were named QRET transients, to distinguish them from FRET transients recorded using DiBAC4(5). The peak ΔF/F of QRET transients elicited by action potential stimulation is twice larger in fibers expressing ECFP-F as those with EGFP-F (7.1% vs. 3.6%). These data provide a unique experimental demonstration of the importance of the spectral overlap in FRET. The voltage sensitivity of QRET and FRET signals was demonstrated to correspond to the voltage-dependent translocation of the charged acceptors, which manifest as nonlinear components in current records. For DPA, both electrical and QRET data were predicted by radial cable model simulations in which the maximal time constant of charge translocation was 0.6 ms. FRET signals recorded in response to action potentials in fibers stained with DiBAC4(5) exhibit ΔF/F amplitudes as large as 28%, but their rising phase was slower than those of QRET signals. Model simulations require a time constant for charge translocation of 1.6 ms in order to predict current and FRET data. Our results provide the basis for the potential use of lipophilic ions as tools to test for fast voltage-dependent conformational changes of membrane proteins in the TTS.
Acetylcholine Receptor Gating: Movement in the α-Subunit Extracellular Domain
Authors: Purohit Prasad , Auerbach Anthony
Published: November 2007

Acetylcholine receptor channel gating is a brownian conformational cascade in which nanometer-sized domains (“Φ blocks”) move in staggering sequence to link an affinity change at the transmitter binding sites with a conductance change in the pore. In the α-subunit, the first Φ-block to move during channel opening is comprised of residues near the transmitter binding site and the second is comprised of residues near the base of the extracellular domain. We used the rate constants estimated from single-channel currents to infer the gating dynamics of Y127 and K145, in the inner and outer sheet of the β-core of the α-subunit. Y127 is at the boundary between the first and second Φ blocks, at a subunit interface. αY127 mutations cause large changes in the gating equilibrium constant and with a characteristic Φ-value (Φ = 0.77) that places this residue in the second Φ-block. We also examined the effect on gating of mutations in neighboring residues δI43 (Φ = 0.86), εN39 (complex kinetics), αI49 (no effect) and in residues that are homologous to αY127 on the ε, β, and δ subunits (no effect). The extent to which αY127 gating motions are coupled to its neighbors was estimated by measuring the kinetic and equilibrium constants of constructs having mutations in αY127 (in both α subunits) plus residues αD97 or δI43. The magnitude of the coupling between αD97 and αY127 depended on the αY127 side chain and was small for both H (0.53 kcal/mol) and C (−0.37 kcal/mol) substitutions. The coupling across the single α–δ subunit boundary was larger (0.84 kcal/mol). The Φ-value for K145 (0.96) indicates that its gating motion is correlated temporally with the motions of residues in the first Φ-block and is not synchronous with those of αY127. This suggests that the inner and outer sheets of the α-subunit β-core do not rotate as a rigid body.
Giant claw reveals the largest ever arthropod
Authors: Braddy Simon J , Poschmann Markus , Tetlie O. Erik
Published: November 2007

The fossil record has yielded various gigantic arthropods, in contrast to their diminutive proportions today. The recent discovery of a 46 cm long claw (chelicera) of the pterygotid eurypterid (‘sea scorpion’)
Jaekelopterus rhenaniae
, from the Early Devonian Willwerath Lagerstätte of Germany, reveals that this form attained a body length of approximately 2.5 m—almost half a metre longer than previous estimates of the group, and the largest arthropod ever to have evolved. Gigantism in Late Palaeozoic arthropods is generally attributed to elevated atmospheric oxygen levels, but while this may be applicable to Carboniferous terrestrial taxa, gigantism among aquatic taxa is much more widespread and may be attributed to other extrinsic factors, including environmental resources, predation and competition. A phylogenetic analysis of the pterygotid clade reveals that
Jaekelopterus
is sister-taxon to the genus
Acutiramus
, and is among the most derived members of the pterygotids, in contrast to earlier suggestions.
Nest-mate recognition in
Manuelia postica
(Apidae: Xylocopinae): an eusocial trait is present in a solitary bee
Authors: Flores-Prado Luis , Aguilera-Olivares Daniel , Niemeyer Hermann M
Published: November 2007

In eusocial Hymenoptera, females are more tolerant towards nest-mate than towards non-nest-mate females. In solitary Hymenoptera, females are generally aggressive towards any conspecific female. Field observations of the nest biology of
Manuelia postica
suggested nest-mate recognition. Experiments were performed involving two live interacting females or one live female interacting with a dead female. Live females from different nests were more intolerant to each other than females from the same nest. Females were more intolerant towards non-nest-mate than towards nest-mate dead females. When dead females were washed with pentane, no differences in tolerant and intolerant behaviours were detected between non-nest-mate and nest-mate females. Females were more intolerant towards nest-mate female carcasses coated with the cuticular extract from a non-nest-mate than towards non-nest-mate female carcasses coated with the cuticular extract from a nest-mate. The compositions of the cuticular extracts was more similar between females from the same nest than between females from different nests. The results demonstrate for the first time nest-mate recognition mediated by cuticular chemicals in a largely solitary species of Apidae. The position of
Manuelia
at the base of the Apidae phylogeny suggests that nest-mate recognition in eusocial species apical to
Manuelia
represents the retention of a primitive capacity in Apidae.
Conspicuous impacts of inconspicuous hosts on the Lyme disease epidemic
Authors: Brisson Dustin , Dykhuizen Daniel E , Ostfeld Richard S
Published: November 2007

Emerging zoonotic pathogens are a constant threat to human health throughout the world. Control strategies to protect public health regularly fail, due in part to the tendency to focus on a single host species assumed to be the primary reservoir for a pathogen. Here, we present evidence that a diverse set of species can play an important role in determining disease risk to humans using Lyme disease as a model. Host-targeted public health strategies to control the Lyme disease epidemic in North America have focused on interruptingBorrelia burgdorferi sensu stricto(ss) transmission between blacklegged ticks and the putative dominant reservoir species, white-footed mice. However,B. burgdorferi ssinfects more than a dozen vertebrate species, any of which could transmit the pathogen to feeding ticks and increase the density of infected ticks and Lyme disease risk. Using genetic and ecological data, we demonstrate that mice are neither the primary host for ticks nor the primary reservoir forB. burgdorferi ss, feeding 10% of all ticks and 25% ofB. burgdorferi-infected ticks. Inconspicuous shrews feed 35% of all ticks and 55% of infected ticks. Because several important host species influence Lyme disease risk, interventions directed at a multiple host species will be required to control this epidemic.
The genetic basis of parallel and divergent phenotypic responses in evolving populations ofEscherichia coli
Authors: Ostrowski Elizabeth A , Woods Robert J , Lenski Richard E
Published: November 2007

Pleiotropy plays a central role in theories of adaptation, but little is known about the distribution of pleiotropic effects associated with different adaptive mutations. Previously, we described the phenotypic effects of a collection of independently arising beneficial mutations inEscherichia coli. We quantified their fitness effects in the glucose environment in which they evolved and their pleiotropic effects in five novel resource environments. Here we use a candidate gene approach to associate the phenotypic effects of the mutations with the underlying genetic changes. Among our collection of 27 adaptive mutants, we identified a total of 21 mutations (18 of which were unique) encompassing five different loci or gene regions. There was limited resolution to distinguish among loci based on their fitness effects in the glucose environment, demonstrating widespread parallelism in the direct response to selection. However, substantial heterogeneity in mutant effects was revealed when we examined their pleiotropic effects on fitness in the five novel environments. Substitutions in the same locus clustered together phenotypically, indicating concordance between molecular and phenotypic measures of divergence.
Can arable field margins be managed to enhance their biodiversity, conservation and functional value for soil macrofauna?
Authors: Smith J. , Potts S. G. , Woodcock B. A. , Eggleton P.
Published: November 2007

The establishment of grassy strips at the margins of arable fields is an agri‐environment scheme that aims to provide resources for native flora and fauna and thus increase farmland biodiversity. These margins can be managed to target certain groups, such as farmland birds and pollinators, but the impact of such management on the soil fauna has been poorly studied. This study assessed the effect of seed mix and management on the biodiversity, conservation and functional value of field margins for soil macrofauna.

Experimental margin plots were established in 2001 in a winter wheat field in Cambridgeshire, UK, using a factorial design of three seed mixes and three management practices [spring cut, herbicide application and soil disturbance (scarification)]. In spring and autumn 2005, soil cores taken from the margin plots and the crop were hand‐sorted for soil macrofauna. The Lumbricidae, Isopoda, Chilopoda, Diplopoda, Carabidae and Staphylinidae were identified to species and classified according to feeding type.

Diversity in the field margins was generally higher than in the crop, with the Lumbricidae, Isopoda and Coleoptera having significantly more species and/or higher abundances in the margins. Within the margins, management had a significant effect on the soil macrofauna, with scarified plots containing lower abundances and fewer species of Isopods. The species composition of the scarified plots was similar to that of the crop.

Scarification also reduced soil‐ and litter‐feeder abundances and predator species densities, although populations appeared to recover by the autumn, probably as a result of dispersal from neighbouring plots and boundary features. The implications of the responses of these feeding groups for ecosystem services are discussed.

Synthesis and applications. This study shows that the management of agri‐environment schemes can significantly influence their value for soil macrofauna. In order to encourage the litter‐dwelling invertebrates that tend to be missing from arable systems, agri‐environment schemes should aim to minimize soil cultivation and develop a substantial surface litter layer. However, this may conflict with other aims of these schemes, such as enhancing floristic and pollinator diversity.
As the raven flies: using genetic data to infer the history of invasive common raven (Corvus corax) populations in the Mojave Desert
Authors: FLEISCHER ROBERT C. , BOARMAN WILLIAM I. , GONZALEZ ELENA G. , GODINEZ ALVARO , OMLAND KEVIN E. , YOUNG SARAH , HELGEN LAUREN , SYED GRACIA , MCINTOSH CARL E.
Published: November 2007

Common raven (Corvus corax) populations in Mojave Desert regions of southern California and Nevada have increased dramatically over the past five decades. This growth has been attributed to increased human development in the region, as ravens have a commensal relationship with humans and feed extensively at landfills and on road‐killed wildlife. Ravens, as a partially subsidized predator, also represent a problem for native desert wildlife, in particular threatened desert tortoises (Gopherus agassizii). However, it is unclear whether the more than 15‐fold population increase is due to in situ population growth or to immigration from adjacent regions where ravens have been historically common. Ravens were sampled for genetic analysis at several local sites within five major areas: the West Mojave Desert (California), East Mojave Desert (southern Nevada), southern coastal California, northern coastal California (Bay Area), and northern Nevada (Great Basin). Analyses of mtDNA control region sequences reveal an increased frequency of raven ‘Holarctic clade’ haplotypes from south to north inland, with ‘California clade’ haplotypes nearly fixed in the California populations. There was significant structuring among regions for mtDNA, with high FST values among sampling regions, especially between the Nevada and California samples. Analyses of eight microsatellite loci reveal a mostly similar pattern of regional population structure, with considerably smaller, but mostly significant, values. The greater mtDNA divergences may be due to lower female dispersal relative to males, lower Ne, or effects of high mutation rates on maximal values of FST. Analyses indicate recent population growth in the West Mojave Desert and a bottleneck in the northern California populations. While we cannot rule out in situ population growth as a factor, patterns of movement inferred from our data suggest that the increase in raven populations in the West Mojave Desert resulted from movements from southern California and the Central Valley. Ravens in the East Mojave Desert are more similar to ones from northern Nevada, indicating movement between those regions. If this interpretation of high gene flow into the Mojave Desert is correct, then efforts to manage raven numbers by local control may not be optimally effective.
Statistical issues on the analysis of change in follow‐up studies in dental research
Authors: Blance Andrew , Tu Yu‐Kang , Baelum Vibeke , Gilthorpe Mark S.
Published: November 2007

Objective:  To provide an overview to the problems in study design and associated analyses of follow‐up studies in dental research, particularly addressing three issues: treatment‐baselineinteractions; statistical power; and nonrandomization.

Background:  Our previous work has shown that many studies purport an interacion between change (from baseline) and baseline values, which is often based on inappropriate statistical analyses. A priori power calculations are essential for randomized controlled trials (RCTs), but in the pre‐test/post‐test RCT design it is not well known to dental researchers that the choice of statistical method affects power, and that power is affected by treatment‐baseline interactions. A common (good) practice in the analysis of RCT data is to adjust for baseline outcome values using ancova, thereby increasing statistical power. However, an important requirement for ancova is there to be no interaction between the groups and baseline outcome (i.e. effective randomization); the patient‐selection process should not cause differences in mean baseline values across groups. This assumption is often violated for nonrandomized (observational) studies and the use of ancova is thus problematic, potentially giving biased estimates, invoking Lord's paradox and leading to difficulties in the interpretation of results.

Methods:  Baseline interaction issues can be overcome by use of statistical methods; not widely practiced in dental research: Oldham's method and multilevel modelling; the latter is preferred for its greater flexibility to deal with more than one follow‐up occasion as well as additional covariates To illustrate these three key issues, hypothetical examples are considered from the fields of periodontology, orthodontics, and oral implantology.

Conclusion:  Caution needs to be exercised when considering the design and analysis of follow‐up studies. ancova is generally inappropriate for nonrandomized studies and causal inferences from observational data should be avoided.
Natural vegetation and ecology of abandoned coal-mined land, Rocky Mountain Foothills, Alberta, Canada
Authors: Russell W. B. , Roi G. H. La
Published: November 2007

The natural vegetation and spoils of two abandoned, unreclaimed coal mines in the Mountain Park area were studied quantitatively in 34 stands. After 26 years of abandonment the vegetation of both Townsite and West Mine was sparse. Total plant cover was usually < 10% and isolated plants were common. The communities were dominated by perennial grasses and forbs. Seven plant community types were recognized: (i) Festuca rubra – Epilobium angustifolium, (ii) Agropyron latiglume –Agropyron repens, and (iii) Agropyron spp. – Artemisia borealis on the Townsite; and (iv) Equisetum arvense – Potentilla fruticosa, (v) Agoseris glauca – Crepis nana, (vi) Agropyron latiglume – Crepis elegans, and (vii) Crepis nana – Eriogonum androsaceum on the West Mine. The spoil materials were generally coarse textured and structureless, consisting of rock fragments and loose single grains. Spoil samples were analysed for 20 physical and chemical properties. Variation in spoil properties appeared to strongly influence plant distribution and community development. Total plant cover and species richness were correlated with several spoil properties; highest correlations were with fine earth content (<2 mm) and clay content on the Townsite and West Mine sites, respectively. Slope position strongly influenced plant distribution on both study sites. Total plant cover, species richness, and the frequency of most species were highest at the slope base and lowest at the upper slope, midslope, and (or) crest positions. The sites were only 1.2 km apart, differed only 30 m in elevation, and were abandoned for the same length of time. Nevertheless, they differed edaphically and supported significantly different plant communities.
Detection of induced susceptibility in tomato using mutants of Cladosporium fulvum tolerant to cycloheximide or benomyl
Authors: Miao Vivian , Higgins Verna J.
Published: November 2007

Mutants of Cladosporium fulvum Cooke tolerant to fungicides incorporated into V8 agar were induced by ultraviolet irradiation of conidia from wild-type isolates. Cycloheximide-tolerant mutants of race 2.3 were recovered at a rate of 2 × 10−6 survivors on media supplemented with 0.5 or 1.0 μg cycloheximide/mL, while benomyl-tolerant mutants of race 4 were recovered at 1 × 10−7 survivors on medium supplemented with 0.1 μg benomyl/mL. Some race 2.3 mutants were resistant to cycloheximide concentrations almost 200 times greater than the selecting concentration. Strain 23C20, a race 2.3 mutant, grew normally on 10 μg cycloheximide/mL, but produced aborted, malformed germ tubes on 0.25 μg benomyl/mL. Strain 4B12, a race 4 mutant tolerant to 0.25 μg benomyl/mL, was also cross tolerant to 0.25 μg thiabendazole/mL, but was sensitive to 0.5 μg cycloheximide/mL. Tolerance persisted on fungicide-free media and through host passage, and was therefore considered genetic rather than adaptive in nature. Competitive fitness of mutants was assessed by replica printing leaflets with sporulation onto fungicide-supplemented and unsupplemented media. Recovery of mutants from mixed infections by such positive selection for fungicide tolerance also made possible studies of induced susceptibility in differential cultivars of tomato. Spores produced by the normally incompatible race 2.3 strain 23C20 could be detected and recovered from ‘Purdue 135’, if plants were preinoculated 1 week before with the compatible race 4 strain 4B12.
Ultrastructure of the host – pathogen relationship in red leaf disease of lowbush blueberry caused by the fungus Exobasidium vaccinii
Authors: Mims Charles W. , Nickerson Nancy L.
Published: November 2007

Actively growing shoots of Vaccinium angustifolium Ait. infected with Exobasidium vaccinii (Fckl.) Woron. contain slender, septate intercellular hyphae bearing short, typically lobed haustoria. Hyphae and haustoria are also present in the apical meristem, where they often distort the shapes of the host cells they contact. The overall structure of the meristem is, however, not significantly altered and leaf primordia continue to develop from the meristem. A rather sparse hyphal system is present in young leaves, but eventually it becomes more extensive and often fills intercellular spaces in the lower portion of the leaf. Numerous haustoria are present in the leaf and are basically similar in structure to those described previously in E. camelliae var. gracilis. Haustoria contain membranous inclusion bodies, and electron-dense penetration matrices are characteristically associated with each haustorium. Overall there is very little host cell wall response to a developing haustorium and no distinct collar of host wall material is associated with the haustorium.
Changes in microtubule organization and wall microfibril orientation during in vitro cotton fiber development: an immunofluorescent study
Authors: Seagull Robert W.
Published: November 2007

Cotton fibers provide an excellent system to study how cortical microtubule arrays are established and the relationship between microtubule organization and wall microfibril deposition. Throughout development, cotton fibers maintain highly organized arrays of microtubules. For the first 15–18 days postanthesis microtubules are oriented transverse to the cell long axis. Older fibers contain microtubule arrays that are organized in a spiral pattern. The switch from transverse to spiral appears to be coordinated along the entire cell length since cells do not simultaneously contain both arrays. Older fibers also exhibit abrupt reversals in microtubule orientation. Reversals occur in two different forms that may represent a developmental sequence in the establishment of reversal regions. Throughout development, the cotton fiber walls exhibit increasing amounts of birefringence. In all cases, the most recently deposited wall microfibrils parallel the cortical microtubules.
The systematic position of the genus Rhinanthus (Scrophulariaceae) in North America
Authors: Hulst Robert van , Thériault Andrée , Shipley Bill
Published: November 2007

North American plants of the genus Rhinanthus are generally designated as R. crista-galli L., or sometimes as R. borealis (Sterneck) Druce or R. stenophyllus (Schur) Druce. The name R. crista-galli, however, has been declared a nomen dubium, and in Europe the corresponding plant is now known as R. minor L. We have compared North American and European material of Rhinanthus on the basis of general morphology, soluble seed proteins, and seed morphology. General morphology proved to be a poor guide to interpopulation variation in these highly plastic plants, even when aided by numerical methods. Seed protein banding has already been shown to be an extremely valuable and stable guide to taxonomy at or below the species level. We have demonstrated four distinct protein banding types in our material: a southeastern Canadian type (S), a northern Canadian type (N), a European type (E), and a hybrid between S and N. Subsequently, we have attempted to allocate populations to the correct seed protein type on the basis of seed morphology alone using discriminant analysis. This allocation is correct in the great majority of cases. We propose that both the southern Canadian and European types be designated as R. minor var. minor (although the two types can in some cases be distinguished on the basis of seed proteins), and that the northern Canadian type be called R. minor var. borealis. We also present a survey of the seed morphological characters that serves to distinguish the two varieties.
Structural variability and invasions of pioneer plant communities in riparian habitats of the middle Adour River (SW France)
Authors: Tabacchi Eric
Published: November 2007

The pioneer vegetation of five distinct littoral zones along the middle Adour River (SW France) was investigated during three successive low water periods. There was a high year to year variability in the hydrology of the river during the period of study with a normal (1987), a wet (1988), and a dry year (1989). Changes in population and life forms density of both native and exotic species were analyzed. Communities were species rich when 45% of the 428 species present in the study area (2-km-long stretch) were found in the 10 × 10 m plots. Most of the species were annuals, but perennials were also abundant. The exotic component represented nearly 20% of the species and of the total number of individuals. There was high spatial variability in pioneer communities; sites of the main river channel differed from those along abandoned arms in species composition and population densities. The communities responded to changes in the hydrology of the preceding growing season. Sharp year to year differences were found in population and species density. The nature of the hydrological change drove those changes. Plots located in the oldest arms of the river showed a greater sensitivity to flooding conditions than those located in young littoral zones, with an increase in hygrophilous species. Alternatively, plots adjacent to active river channels showed greater sensitivity to drought conditions, as the density of short-lived and exotic species increased. Comparatively, exotics appeared to be more sensitive to the type of hydrological changes than natives. Warmer years also affected native plants, which reacted like invasive species. Relationships between the observed changes, the level of hydrological disturbance, and the recent history of each site are discussed in this paper with the possibility of using introduced species as descriptors of climatic and hydrologic changes. Key words: riparian vegetation, pioneer community, community structure, biological invasions, hydrological perturbation, variability.
Compensatory growth of three grasses following simulated grazing in relation to soil nutrient availability
Authors: Hicks Samantha L. , Reader R. J.
Published: November 2007

This study tested predictions about the effect of soil nutrient availability on compensatory growth by grazed plants. A factorial experiment was conducted in the greenhouse to examine effects of soil nutrient availability (three soil types differing in content of nitrogen, phosphorus, potassium, and magnesium) on total leaf length and biomass of three perennial grasses (Poa compressa, Poa pratensis, and Dactylis glomerata) that were subjected to simulated grazing (plants clipped 2 cm above the soil). Clipped plants of D. glomerata were not able to compensate for lost biomass in one soil type, and clipped plants of P. pratensis did not compensate for an initial reduction in total leaf length in another soil type. Otherwise, clipped plants compensated for lost biomass or leaf length independent of soil type. These results indicate that soil nutrient availability may affect compensatory growth by clipped plants, but compensatory responses of the three grasses studied here were only partly consistent with predictions of current models. Key words: herbivory, regrowth, nutrients, Poa, Dactylis.
Predicting the effects of different harvesting regimes on forest floor dynamics in northern hardwoods
Authors: Aber John D. , Botkin Daniel B. , Melillo Jerry M.
Published: November 2007

The effects of different intensities of forest management on forest floor organic matter and nitrogen dynamics in northern hardwoods were simulated with a computer model built from the extensive data base of the Hubbard Brook Ecosystem Study. Three cutting intensities and three rotation lengths were tested. In all cases, both nitrogen availability and forest floor organic matter declined for 15–30 years following cutting and required 60–80 years to recover to precut levels. Rotation length had a much greater effect on the forest floor than harvesting intensity with short-rotation (30-year) complete forest harvesting causing the greatest reduction in both biomass and nitrogen availability. Average forest floor biomass under this treatment was reduced to roughly one-half of that under clear-cutting (90-year rotation).
Ten-year growth response of midrotation slash pine plantations to control of competing vegetation
Authors: Oppenheimer Michael J. , Shiver Barry D. , Rheney John W.
Published: November 2007

In 1976 a competing vegetation experiment using treated and control plots was installed across four soil drainage groups in 9- to 15-year-old site-prepared slash pine (Pinuselliottii Engelm.) plantations located throughout the lower coastal plain of Georgia and north Florida. All understory vegetation was removed from treated plots, which were then kept relatively free of competing vegetation for 10 years. Analysis of covariance revealed that treatment had a significant effect on height, basal area, and total and merchantable volume growth per tree and per hectare over the 10-year period. Both soil drainage group and its interaction with treatment were found to be nonsignificant for each response variable. Average stand height increased 7.1% (0.44 m) more on treated than on control plots, and average basal area per tree increased 18.4% (0.0019 m2) more after 10 growing seasons. Net total and merchantable volume growth per hectare during the 10 years increased by 13.2% (17.6 m3/ha) and 15.2% (15.7 m3/ha), respectively. Percent increases in net merchantable and total volume growth per hectare leveled off after about 4 years, but the absolute differences continued to increase throughout the 10-year measurement period.
The mycorrhizal condition of weakened Scots pine saplings grown on ploughed sites in northern Finland
Authors: Väre H.
Published: November 2007

The mycorrhizal condition of nursery-grown containerized Scots pine (Pinussylvestris) saplings planted in clear-cut and ploughed sites in northern Finland was investigated. The saplings, 15 years old on average, were classified on the basis of shoot condition into injured and healthy-looking saplings on the ploughed sites and control saplings on the adjoining natural sites. Ploughing after clear-cutting resulted in reduced mycorrhiza formation, the average percent infection being below 20 for injured saplings and between 60 and 85 for the control saplings. Formation of the mantle and Hartig net was weak in the injured saplings and reduced in the healthy-looking saplings compared with the control saplings, where the mantle had a mean thickness of 31.3 μm and the Hartig net was fully developed. The number of short roots and the short root biomass were greatly reduced in the healthy-looking saplings compared with the control saplings. These results indicate that the practice of ploughing in the clear-cut areas of northern Finland had caused a marked reduction in the growth of the whole short root system and in the formation of mycorrhizae in both the injured and healthy-looking saplings. The poor formation of mycorrhizae is clearly linked to the reduced growth of shoots at these sites.
The effects of several herbicides on the germination of seeds in the forest floor
Authors: Morash R. , Freedman B.
Published: November 2007

In a laboratory experiment, we studied the effects of perturbation of a forest floor substrate with six concentrations (10, 50, 100, 500, 1000, and 5000 ppm) of four herbicides: glyphosate (N-phosphonomethyl glycine), 2,4,5-T (2,4,5-trichlorophenoxy acetic acid), triclopyr (3,5,6-trichloro-pyridinyloxyacetic acid), and two formulations of hexazinone (3-cyclohexyl-6-(dimethylamino)-1-methyl-1-1,3,5-triazine-2,4(1H,3H)dione). Although their toxic thresholds differ, the herbicides all caused significant decreases in the germination of seeds. However, large decreases in germination only occurred at concentrations that are unrealistically large in comparison with the herbicide residues that actually occur after a silvicultural treatment. In a parallel field experiment, no significant difference in seedling germination was observed for forest floor samples that were exposed to or shielded from herbicide deposition at two sites that were sprayed in an operational program.
Tree windthrow and forest soil turnover
Authors: Norton D. A.
Published: November 2007

Soil turnover as a result of tree windthrow has an important influence on soil development and plant distribution in forests. Estimates of the time needed for soil turnover in a given area are often made, but unless these take into account the potential for reestablishment of canopy trees onto sites previously affected by windthrow, they are likely to substantially underestimate turnover time. Soil turnover is not a regular, uniform process, but rather results in a mosaic of soils with different turnover histories. Because soil turnover follows an exponential decay model, some area of soil will never be turned over. As it is therefore not possible to define the time when all the soil in an area has been turned over, it is proposed that soil turnover half-life (the time at which half the soil has been turned over) be used as a measure of soil turnover.
The effect of stand structure and stand density on the leaf area–sapwood area relationship of lodgepole pine
Authors: Thompson Dan C.
Published: November 2007

The relationship of sapwood area to leaf area in lodgepole pine was examined across a variety of habitat types and stand densities in northwest Montana. No statistical differences were found between plots with regard to either habitat type or stand density. A nonlinear relationship was found between leaf area and sapwood area. Increasing amounts of sapwood were associated with a decrease in the leaf area–sapwood area ratio. A large amount of within-plot variation in the sapwood area–leaf area relationship was explained by differences between dominant trees and trees of other crown classes. Leaf area (LA) was best estimated by the equation LA = 0.12 × S − 0.0003 × S2 + 0.06 × S × D, where LA is leaf area, S is sapwood area, and D is the crown class (dominant). Differences between dominant and subdominant trees appear to be related to ring width and its associated permeability. Differences in sapwood area–leaf area equations among different studies may be due in part to differences in stand structure.
EXCHANGE COUPLING AND ENHANCEMENT OF CURIE TEMPERATURE OF THE INTERGRANULAR AMORPHOUS REGION IN NANO-CRYSTALLINE DUPLEX-PHASE ALLOYS SYSTEM
Authors: SHAO Y. Z. , ZHONG W. R. , LIN G. M. , HU X. D.
Published: November 2007

We studied the theoretical Curie temperature of a dual-phase nanomagnetic system by Monte Carlo simulation of a modified Heisenberg model on a 3D complex lattice consisting of single- and cluster-spins. We also systematically investigated the experimental Curie temperature of a dual-phase nanomagnetic alloy and performed a direct comparison between theory and experiment. The exchange coupling between two component magnetic phases substantially affects the Curie temperature [Formula: see text] of the intergranular amorphous region of a dual-phase nanomagnetic system. The [Formula: see text] depends upon the nanocrystallite size d, the volume fraction Vc and the interspace among crystallites ξ. Large crystallized volume fraction Vc, small grain size d, and thin interphase thickness ξ lead to an obvious enhancement of Curie temperature (ECT) of intergranular amorphous region, whereas the Curie temperature of nanocrystallites [Formula: see text] decreases slightly. By simulation, we worked out a relationship between the reduced ECT and ξ, as [Formula: see text], and it conforms to the experimental result. In addition, we also simulated the demagnetization of a hard–soft nanocomposite system. The exchange coupling between two component phases affects the cooperativity of two-phase magnetizations, the coherent reversal of magnetizations, and coercivity.
Optimization of Acetylene Black Conductive Additive and Polyvinylidene Difluoride Composition for High Power Rechargeable Lithium-Ion Cells
Authors: Liu Gao , Zheng Honghe , Battaglia Vince , Simens Amanda S. , Minor Andrew M. , Song Xiangyun
Published: November 2007

Fundamental electrochemical methods were applied to study the effect of the acetylene black (AB) conductive additive and the polyvinylidene difluoride (PVDF) polymer binder on the performance of high-power designed rechargeable lithium ion cells. A systematic study of the AB/PVDF long-range electronic conductivity at different ratios is performed using four-point probe direct current tests and the results reported. There is a wide range of AB/PVDF ratios that satisfy the long-range electronic conductivity requirement of the lithium-ion cathode electrode; however, a significant cell power performance improvement is observed at small AB/PVDF composition ratios that are far from the long-range conductivity optimum of 0.8 to 1. Electrochemical impedance spectroscopy and the hybrid power pulse characterization tests indicate that the impedance decreases significantly with increase in binder content. We believe the higher binder contents lead to a more cohesive conductive carbon particle network that results in better overall all local electronic conductivity on the active material surface and hence reduced charge transfer impedance.
Physisorption of Hydrogen on Boron-Containing Carbon (B/C) Material Prepared by Organoborane Precursor
Authors: Chung T. C. M. , Chen Wei , Zhang Zhicheng
Published: November 2007

This paper discusses the synthesis of boron substituted carbon (B/C) materials by pyrolysis of two organic and polymeric precursors, which are prepared by chloroboration of phenylene acetylene and phenyl diacetylene, respectively. Some of the resulting B/C materials were evaluated in hydrogen physisorption from ambient to low temperatures under various hydrogen pressures. Evidently, through the precursor design it is possible to transform some B atoms in the precursor into B/C material by pyrolysis. Despite the dense structure (without significant porosity by SEM and BET), the B/C material with 1.6 wt% B content shows hydrogen absorption 0.7 and 2.15 wt% at 25 and -78 oC, respectively, under 1300 psi hydrogen pressure. The adsorption-desorption cycles were repeated many times without any detectable change. Apparently, the empty p-orbital in the substituted B atom increases the binding energy of hydrogen to the B/C surface of graphitic platelet , which is reversible by pressure and ambient temperature.
Fermentation, Phlogiston and Matter Theory: Chemistry and Natural Philosophy in Georg Ernst Stahl's Zymotechnia Fundamentalis
Authors: Chang Ku-Ming
Published: November 2007

This paper examines Georg Ernst Stahl's first book, the Zymotechnia Fundamentalis, in the context of contemporary natural philosophy and the author's career. I argue that the Zymotechnia was a mechanical theory of fermentation written consciously against the influential "fermentational program" of Joan Baptista van Helmont and especially Thomas Willis. Stahl's theory of fermentation introduced his first conception of phlogiston, which was in part a corpuscular transformation of the Paracelsian sulphur principle. Meanwhile some assumptions underlying this theory, such as the composition of matter, the absolute passivity of matter and the "passions" of sulphur, reveal the combined scholastic and mechanistic character of Stahl's natural philosophy. In the conclusion I show that Stahl's theory of fermentation undermined the old fermentational program and paved the way for his dualist vitalism.
Locke, Bacon and Natural History
Authors: Anstey Peter R.
Published: November 2007

This paper argues that the construction of natural histories, as advocated by Francis Bacon, played a central role in John Locke's conception of method in natural philosophy. It presents new evidence in support of John Yolton's claim that "the emphasis upon compiling natural histories of bodies ... was the chief aspect of the Royal Society's programme that attracted Locke, and from which we need to understand his science of nature". Locke's exposure to the natural philosophy of Robert Boyle, the medical philosophy of Thomas Sydenham, his interest in travel literature and his conception of the division of the sciences are examined. From this survey, a cumulative case is presented which establishes, independently of an in-depth exegesis of his Essay Concerning Human Understanding, the central role for Locke of the construction of natural histories in natural philosophy.
Clinical Evaluation of Vascoray (Sodium Iothalamate 26%/Methylglucamine Iothalamate 52%)—a New Contrast Medium
Authors: Marshall T.R.
Published: November 2007

A clinical comparison and use of a new salt mixture of iothalamate—Vascoray (sodium iothalamate 26%/methylglucamine iothalamate 52%)—with Conray (methylglucamine iothalamate 60%), Conray-400 (sodium iothalamate, 66.8%), Hypaque-M 75% (sodium diatrizoate 25%/methylglucamine diatrizoate 50%) and Angio-Conray (sodium iothalamate 80%) has been carried out. The sodium solutions were found to produce more major and minor side effects, to have the lowest viscosity, and be more irritating to the myocardium, cerebral circulation, and spinal cord. The methylglucamine solutions had fewer side effects, but a greater viscosity for a similar iodine content.

A combination of the sodium and methylglucamine salts of iothalamate and diatrizoate produced fewer side effects in the procedures compared, Table III. The iothalamate compound produced fewer side effects than the diatrizoate compound, Table III.

Vascoray is a sterile solution of 400 mg of organically bound iodine per ml (40% iodine). Each ml contains 260 mg of sodium and 520 mg of methylglu camine as mixed salts of iothalamic acid and not more than 0.15 mg sodium biphosphate as a buffer. This compound was formulated because of the increas ing need for an agent with fewer major and minor side effects for aortography and angiocardiography. It has a viscosity of 14.0 centipoises at 25°C, and 9.0 centipoises at 37.5°C.

The intravenous LD 50 (mice) for methylglucamine iothalamate 60% is 17,000 mg/kg; sodium iothalamate 66.8% is 19,000 mg/kg; sodium iothalamate 26%/ methylglucamine iothalamate 52% is 18,000 mg/kg; and sodium iothalamate 80% is 21,000 mg/kg, Table I. Hayes2 has reported that all standardized toxic ity studies comparing iothalamate preparations and diatrizoate preparations proved the iothalamate preparations to be less toxic than the diatrizoate prepa rations as regards neurotoxicity, nephrotoxicity and cardiopulmonary toxicity. Gensini3 has suggested that the methylglucamine salt may be safer than the sodium salt in the coronary arteries, myocardium and spinal cord tissues. So dium salts are more toxic to the spinal cord, coronary arteries and myocardium than the methylglucamine salts. Methylglucamine salts are generally accepted as less toxic than sodium salts; however, they have a higher viscosity than sodium solutions. The combination of the two salts reduced the side effects while maintaining adequate flow rates, since the sodium solution has a lower viscosity and faster flow rate. This new agent combines the low toxicity-high viscosity of methylglucamine iothalamate with somewhat higher toxicity-lower viscosity of sodium iothalamate.
Selective Coronary Angiography with Iodamide
Authors: Kaude Jüri V. , Lunderquist Anders , Persson Stig , Arnman Krister
Published: November 2007

The myocardial toxicity of iodamide (Jodomiron 380) in selective coronary angiography was compared with that of metrizoate (Isopaque coronar). Electrocardiographic changes, systolic blood pressure and heart rate were registered and compared in a total of 106 injections. Both contrast media produced transient changes in ST-segment and T-wave, reduced the heart rate and systolic blood pressure. Differences noted were: a more marked hypotensive effect after injection of Jodomiron into the left coronary artery, and a higher frequency of moderate electrocardio graphic changes at injection of Isopaque into the right coronary artery. Because of the small number of registrations, however, these differences were not conclusive. The diagnostic quality of examination with both contrast media was excellent.
Venous Pressure and Compliance of the Peripheral Capacitance Vessels
Authors: Kato Masataka , Saiki Sechi , Ogino Tadayoshi , Suzuki Tomoyuki , Kojima Arao , Koeda Toshihiko , Kimura Takeshi
Published: November 2007

Compliances of the peripheral capacitance vessels decreased gradually in accordance with the increase in pressure of the brachial vein. The relationship between them formed a number of hyperbolic-like curves, the same results as those found in many cases of both normal subjects and patients with congestive heart failure. The decrease of compliance of the peripheral capacitance vessels was not the result of an organic change, but of a functional change of the vessels caused by distention.
Utilization of a Tomographic Attachment for "Moving Band" Arteriography
Authors: Kovac Alexander , Kuo Yen-Zen
Published: November 2007

By using a slit plate, scanographic arterial studies can be performed with a tomographic attachment of an X-ray unit that is normally used for routine radiographic examinations. The expense is minimal and no structural changes are necessary.
Vertebral Osteomyelitis Following Translumbar Aortography
Authors: Schwartz Harold , Berkow Andrew E. , Love Leon
Published: November 2007

Translumbar aortography is the method of choice for abdominal angiog raphy in patients whose vascular disease precludes use of the Seldinger technique via the transfemoral or transaxillary route. Complication rates have decreased with the use of teflon catheters. A case in which vertebral osteomyelitis developed after translumbar aortography is presented.
Pathophysiology of Capillary Circulation: Raynaud's Disease
Authors: Arnot R.S. , Boroda C. , Peacock J.H.
Published: November 2007

Despite the frequency of Raynaud's disease in cold climates, the etiology of the condition remains uncertain. This report reviews the literature since Raynaud's original description and Lewis and Pickering's addition to the concept, and several recent observations which add to our understanding of the disease are discussed.

We investigated the effect of posture and a vasodilator drug on the digital capillary circulation; digital blood flow increases as the body moves from a recumbent, through a sitting, to an upright position. Bradilan, a vasodilator drug, increases the circulation in the recumbent and sitting positions, but has no effect in standing patients, despite symptomatic relief.
Long Injection Time and Biplane Oblique Patient Positioning in Femoral Arteriography
Authors: Paster Stuart B. , Burstein Jerome , Antoine John E.
Published: November 2007

We have made several important changes in femoral arteriography, includ ing a slower rate, longer injection time, and the use of biplane oblique views. The long injection time has resulted in fewer repeat examinations. Biplane oblique filming of the pelvis has increased our ability to demonstrate stenoses and abnormalities, although it has not significantly increased the information content of the studies.