bluuebunny/crossref_metadata_2025 huggingface dataset:
The oceanic crust: Investigations by Canadian groups on the Mid-Atlantic Ridge crest and other areas
Authors: Hall J. M.
Published: June 2009

The last decade has seen a major Canadian contribution to the understanding of the oceanic crust in the area of the Mid-Atlantic Ridge crest. Intensive investigations using a wide range of geological and geophysical techniques, including drilling from D.V. GLOMAR CHALLENGER, have led to detailed information being available for the ridge crest areas at 37°N and 45°N latitude. The information includes bathymetry, crustal age from magnetic and other methods, crustal lithology and layering, basalt petrology, geochemistry and alteration, heat flow, and the physical properties of crustal rocks. From this information significant new models of crustal formation, tectonics, and evolution have been developed. Important features of these models are the episodicity of crustal formation processes on time scales of the order of 105 years or less, the need to search for magnetic anomaly sources at depth in the oceanic crust, and the suggestion that the upper part of basaltic oceanic layer 2 is highly disturbed tectonically. Contributions to knowledge of North Atlantic ocean islands, representing areally small but typical parts of oceanic crust, have come from a series of drilling investigations. Major results include the two-stage formational history of the Bermuda seamount and evidence for large and rapid subsidence, and for active geothermal systems in Iceland and the Azores.
Paleoclimatic implications of a Late Wisconsinan insect assemblage from Rostock, southwestern Ontario
Authors: Pilny Jerry J. , Morgan Alan V. , Morgan Anne
Published: June 2009

The Rostock site is situated in a peat-covered wetland where fragments of a mammoth (Mammuthus primigenius) were unearthed in 1982. Excavation showed a descending sequence of peat, silty marl, gravel, clayey silt, and till. Approximately 300 kg of sediment was taken from the section for pollen, invertebrate, and geochemical analyses. The peat–marl transition is believed to be approximately contemporaneous with the spruce–pine transition in southern Ontario (ca. 10 600 years BP). A date of 10 790 ± 150 years BP on collagen from mammoth tusk fragments recovered from the same level substantiates this inference.Insects, especially Coleoptera, were common throughout the marl and represent at least 2000 individuals from 16 different families. On the basis of beetle ecologies and modern distributions, the marl was subdivided into lower and upper horizons. The lower horizon contains many species that are today restricted to western and northern North America. They are typical residents of the northern Boreal Forest Region and are frequently found on barren, sparsely vegetated ground. The upper horizon contains species found in and to the south of the boreal forest. Phytophagous species are more numerous and indicate a change from sparse to abundant vegetation. The insect assemblages suggest a shift from cold, tree-line conditions to a cool, temperate environment between approximately 13 000 and 11 000 years BP.
Reef trilobites from the Formosa Limestone (Lower Devonian) of southern Ontario
Authors: Ludvigsen Rolf
Published: June 2009

A reef trilobite fauna of five species from the Formosa Limestone Member of the Amherstburg Formation (Lower Devonian, Emsian) of southern Ontario is strongly dominated by the proetids Crassiproetus and Mannopyge; it also includes the brachymetopid Mystrocephala, the lichid Acanthopyge, and the aulacopleurid Harpidella. This is the first fully documented trilobite fauna from North American Devonian reefs. The proetid-dominated Formosa reef fauna from the Appalachian Province is more similar to Carboniferous reef trilobite faunas than it is to other Devonian reef trilobite faunas from the Old World Province in Europe, Africa, and Australia that are dominated by scutelluids. Crassiproetus Stumm is assigned to the Proetinae; Mannopyge n. gen. (type species, M. halli (Stumm)), to the Warburgellinae.
Sulphide erratics applied to subglacial exploration: St. Elias Mountains, British Columbia
Authors: Day S. J. , Broster B. E. , Sinclair A. J.
Published: June 2009

Petrographic and geochemical data from glacial erratics provide evidence for a hidden subglacial source when compared with data from the only known sulphide deposit outcropping locally. These results are found to be in agreement with geological and glaciological studies conducted as part of a reconnaissance exploration program. It is suggested that the integrated approach described here is an inexpensive and rapid exploration method that can determine the likelihood of additional sub-glacial occurrences in areas of known deposits.
Lateral and vertical facies sequences in the Upper Cretaceous Chungo Member, Wapiabi Formation, southern Alberta
Authors: Rosenthal Lorne R. P. , Walker Roger G.
Published: June 2009

The Chungo Member of the Wapiabi Formation (Campanian) shales out northward and (or) eastward from Lundbreck to the Bow Valley, southern Alberta. At Lundbreck, basinal mudstones are overlain by turbidite and hummocky cross-stratified sandstones in an overall coarsening-upward sequence. The marine part of the sequence is capped by dominantly swaley cross-stratified sandstones, interpreted as storm-dominated shoreface deposits. Nonmarine fluvial deposits overlie the shoreface. Essentially the same sequence persists northward to the area of the Highwood River, but in the Highwood River – Sheep River – Longview area, the swaley cross-stratified shoreface sandstones are progressively cut out by a north- and (or) east-ward-dipping erosion surface with up to 40 m of relief. The erosion surface is overlain by a lag of chert pebbles and then by a marine coarsening-upward sequence of offshore to shoreface deposits (the lower tongue of the Nomad Member). Nonmarine Chungo deposits then prograded north- and (or) eastward to overlie this marine tongue in the Highwood area. They are in turn abruptly overlain by a gravel-coated transgressive surface marking the upper marine tongue of the Nomad Member. Finally, marine shales of the Nomad Member are abruptly overlain by dominantly fluvial rocks of the Belly River Formation.We suggest that the main Chungo shoreface, stratigraphically equivalent to the Milk River sandstone of southeastern Alberta, prograded north- and (or) eastward to at least the Highwood River area. A rapid relative lowering of sea level followed by stillstand resulted in the formation of the erosion surface and the supply of gravel to the basin. The overlying coarsening-upward sequence indicates the resumption of shoreline progradation, but this appears to have been relatively short-lived; it was terminated by the transgression of the upper Nomad tongue.
Breakup of small rivers in the subarctic
Authors: Woo Ming-ko , Heron Richard
Published: June 2009

At the end of the winter, the channels of small, subarctic rivers in the coastal James Bay Lowland are filled with snow, river ice, and icing. The major processes associated with the breakup of these rivers include the melting of the snow cover and the resultant generation of meltwater, the impoundment of meltwater runoff by snow dams, the disintegration and ablation of the river ice cover, the formation and dissipation of ice jams, and an exchange of overland and channelled flow between the rivers and their adjacent wetlands. A generalization of the breakup sequences allows a qualitative prediction of the events for specific segments of the channel. Findings of this study are applicable to the many small, subarctic rivers that fringe the James Bay and Hudson Bay coasts.
A newly discovered skull of the temnospondyl amphibian Dendrerpeton acadianum Owen
Authors: Godfrey Stephen J. , Fiorillo Anthony R. , Carroll Robert L.
Published: June 2009

A virtually complete three-dimensional skull of a subadult of the temnospondyl amphibian Dendrerpeton acadianum provides new information on the structure of the palate and lower jaw. The left stapes appears to lie in a natural position on the quadrate ramus of the pterygoid. The proportionately large otic ossicle probably precluded it from having acted as a transmitter of airborne vibrations from a tympanum to the inner ear. The use of the term "otic notch" should be restricted to amphibians or reptiles in which the embayment of the posterior margin of the cheek is accompanied by the presence of a slender rod-like stapes that could have functioned as part of an impedance matching system. In those species in which a notch is present but the stapes is a massive "supporting" element, the term "squamosal embayment" should be used, rather than "otic notch." The squamosal embayment in early tetrapods may have been inherited directly from their fish ancestors and had no functional relationship to hearing.
Directional orientations of solitary rugose corals
Authors: Elias Robert J. , McAuley Robert J. , Mattison Blair W.
Published: June 2009

Unattached solitary rugose corals lying parallel to bedding are common in many Ordovician and younger Paleozoic units, but their directional orientations have seldom been examined. Interpretations based on occurrences in North American Upper Ordovician and Lower Silurian strata provide a foundation for such studies. Distinct directional patterns resulted from preferred orientation with respect to water motion. They indicate transportation rather than biologic orientation, if it can be shown that the corals were not preserved in life position or were abraded to a significant degree before burial. Transported, slightly curved specimens having trochoid to ceratoid form were aligned parallel to currents, with the apex pointing upstream, and (or) were rolled nearly perpendicular to currents or almost parallel to crests of advancing waves, with the apex facing either way but directed slightly upstream. Therefore, unimodal orientation patterns, bimodal patterns with equal peaks that are opposite one another but slightly skewed, and trimodal patterns that are a combination of these can be used to determine flow directions. An apparently bimodal pattern with nearly equal and directly opposite peaks has been observed in a case involving mostly subcalceoloid corals. These individuals may have been aligned parallel to currents or to the direction of wave progression, with the apex facing either way. Random directional distributions do not necessarily indicate low-energy environments. They could have resulted from changes in flow direction during the time in which the sampled stratigraphic interval was deposited or from the effects of bioturbation on corals that were initially preferentially oriented.Directional patterns of solitary rugose corals are of value in paleoecology (recognition of transported assemblages) and basin analysis (determination of paleocurrent directions). They may also prove to be useful in making paleoenvironmental reconstructions (type of water motion, nature of substrate) if the reasons for different types of orientation patterns can be established with experimental work and additional data from the geologic record.
Rb–Sr geochronology and metamorphic history of Proterozoic to early Archean rocks north of the Cape Smith Fold Belt, Quebec
Authors: Doig Ronald
Published: June 2009

The Churchill Province north of the Proterozoic Cape Smith volcanic fold belt of Quebec may be divided into two parts. The first is a broad antiform of migmatitic gneisses (Deception gneisses) extending north from the fold belt ~50 km to Sugluk Inlet. The second is a 20 km wide zone of high-grade metasedimentary rocks northwest of Sugluk Inlet. The Deception gneisses yield Rb–Sr isochron ages of 2600–2900 Ma and initial ratios of 0.701–0.703, showing that they are Archean basement to the Cape Smith Belt. The evidence that the basement rocks have been isoclinally refolded in the Proterozoic is clear at the contact with the fold belt. However, the gneisses also contain ubiquitous synclinal keels of metasiltstone with minor metapelite and marble that give isochron ages less than 2150 Ma. These ages, combined with low initial ratios of 0.7036, show that they are not part of the basement, as the average 87Sr/86Sr ratio for the basement rocks was about 0.718 at that time.The rocks west of Sugluk Inlet consist mainly of quartzo-feldspathic sediments, quartzites, para-amphibolites, marbles, and some pelite and iron formation. In contrast to the Proterozoic sediments in the Deception gneisses, these rocks yield dates of 3000–3200 Ma, with high initial ratios of 0.707–0.714. These initial ratios point to an age (or a provenance) much greater than that of the Archean Deception gneisses. The rocks of the Sugluk terrain are intruded by highly deformed sills of granitic rocks with ages of about 1830 Ma, demonstrating again the extent and severity of the Proterozoic overprint. The eastern margin of this possibly early Archean Sugluk block is a discontinuity in age, lithology, and geophysical character that could be a suture between two Archean cratons. It is not known if such a suturing event is of Archean age, or if it is related to the deformation of the Cape Smith Fold Belt.Models of evolution incorporating both the Cape Smith Belt and the Archean rocks to the north need to account for the internal structure of the fold belt, the continental affinity of many of the volcanic rocks, the continuity of basement around the eastern end of the belt, and the increase in metamorphism through the northern part of the belt into a broad area to the north. The Cape Smith volcanic rocks may have been extruded along a continental rift, parallel to a continental margin at Sugluk. Continental collison at Sugluk would have thrust the older and higher grade Sugluk rocks over the Deception gneisses, produced the broad Deception antiform, and displaced the Cape Smith rocks to the south in a series of north-dipping thrust slices.
Geochemical and Sr and Nd isotopic constraints on the origin of late Proterozoic volcanics and associated tin-bearing granites from the Franklin Mountains, west Texas
Authors: Norman David I. , Condie Kent C. , Smith Robert W. , Thomann W. F.
Published: June 2009

Late Proterozoic volcanic and granitic rocks from the Franklin Mountains in west Texas define a continuous tholeiitic trend from rhyolite (granite) to trachyte with a small compositional gap between trachyte and basalt. Volcanics and granitic rocks have immobile-element geochemical affinities with volcanics from continental-margin-arc systems and associated back-arc basins. Felsic volcanics and granitic rocks appear to have formed by fractional crystallization of basalt during which REE and high-field-strength elements were stabilized as fluoride complexes and concentrated in late or post-magmatic fluids.A Rb–Sr isochron from nonhematized samples (1064 ± 5 Ma, i = 0.7034) falls within the error of reported U–Pb zircon dates and probably dates a period of hydrothermal alteration. εNd values (0.7–2.5 at 1065 Ma) fall below a depleted mantle growth curve and probably reflect contamination of the fractionating magmas with older continental crust. Changes in the isotopic composition of Nd during hydrothermal alteration may also contribute to the spread in εNd values.
Distribution et comportement du bore dans la croûte océanique
Authors: Bergeron Mario
Published: June 2009

The behaviour of boron involved in alteration of oceanic crust by sea water was investigated by means of prompt gamma neutron activation analysis of basalt and serpentinite samples from in situ oceanic crust and ophiolites. The samples were grouped in the following categories: fresh basalts, low-temperature altered basalts, high-temperature altered basalts, and serpentinites.The average B content in fresh basalts is 2.2 ± 0.6 ppm. The low-temperature altered basalts and the serpentinites are 2–24 times richer in B than the fresh basalts. The alteration of the crust at low temperature and its serpentinization imply B extraction from sea water. The rate of B removal for this specific low-temperature alteration of basalts is estimated to be 10.5 × 1010 g/year, on the basis of the development of altered zones in the crust and of the B contents of these zones before and after their alteration.The high-temperature altered basalts having a low water/rock ratio show an average B content (2.3 ± 0.7 ppm) similar to that of fresh basalts, indicating that the alteration of the crust at high temperature has not affected the B content of those rocks under conditions of limited fluid access to the system. However, if high-temperature alteration is associated with high water/rock ratios, a solubilization of B in the hydrothermal fluids migrating through the crustal zones is to be expected. Our data and previously published results cannot provide a reliable estimate of B flows related to high-temperature alteration of the crust and to serpentinization, significantly constraining the establishment of the oceanic B budget. [Journal Translation]
Diagenetic evolution of a Late Silurian reef platform, Gaspé Basin, Quebec, based on cathodoluminescence petrography
Authors: Savard Martine , Bourque Pierre-André
Published: June 2009

Carbonate units of two facie of the platformal upper reef complex of the Late Silurian West Point Formation, Gaspé Peninsula, Quebec, were studied to decipher their diagenetic evolution. The two facies were a reef-margin facies and a back-reef to lagoonal facies. Under the light microscope, only three broad cement phases were recognized. In contrast, cathodoluminescence observation revealed seven distinct generations of cements and a plethora of additional diagenetic features such as fracturing, internal brecciation, sulfatization, and stylolitization. The first four generations of cement were early marine and confined to the reef-margin facies. The subsequent three cement generations evolved in shallow to deeper burial environments and affected the reef-margin facies and the back-reef to lagoonal facies. C and O stable-isotope data support these deductions. Fracturing, internal brecciation, stylolitization, sulfatization, and the generation of the latest cements occurred during compaction and postcompaction stages. Lithification of the facies was rapid, with the pores completely occluded before a maximum burial depth of about 1 km was attained (based on conodont colour-alteration indices, organic-matter maturation data, and overall post-Silurian paleogeography).
Paleomagnetic and pollen chronostratigraphic correlations of the late glacial and postglacial sediments in Lake Ontario
Authors: Carmichael Charles M. , Mothersill John S. , Morris William A.
Published: June 2009

Lake Ontario is divided by two ridges of glacial till into three basins — Niagara, Mississauga, and Rochester in the western, central, and eastern parts, respectively, of the lake. Piston and benthos cores were taken by the Canada Centre for Inland Waters from each of the three basins from the research ship CSS Lymnos. The lithology, mineralogy, pollen content, and magnetic parameters of the sediment in these cores have been studied as a means of chronostratigraphic correlation. The transition from late glacial to postglacial sediment is inferred to take place where there is a marked increase in the numbers of pollen in the cores. Further chronostratigraphic correlation between cores has been based mainly on simultaneous matching of the magnetic parameters of declination, inclination, intensity, and ratio of natural remanent magnetization (NRM) to anhysteretic remanent magnetization (ARM). Type curves of declination, inclination, and NRM/ARM for Lake Ontario have been produced.
Early Cretaceous foraminifera from the Middle and Upper Mannville and Lower Colorado subgroups in the Cold Lake Oil Sands area of east-central Alberta: stratigraphic and paleoenvironmental implications
Authors: Mattison Blair W. , Wall John H.
Published: June 2009

The regional deposits of the Middle and Upper Mannville subgroups of east-central Alberta are characterized by a series of stacked offshore-paralic successions which represent transgressive–regressive cycles superimposed upon a longer term regressional trend. This trend eventually resulted in the complete withdrawal of the lower Albian Clearwater sea from eastern Alberta and western Saskatchewan. The marine deposits of the Clearwater sea (the Clearwater shales) carry the lower Albian Verneuilinoides cummingensis – Marginulinopsis collinsi foraminiferal assemblage. The next diagnostic foraminiferal assemblage, the upper Albian Haplophragmoides gigas fauna, is found in the Joli Fou shales of the Colorado Group which overlie the Mannville Group. Middle Albian strata are absent between the Mannville and the Colorado in eastern Alberta, but the exact placement of the maximum corresponding unconformity has been controversial. This study indicates that the uppermost unit of the Mannville (the Colony unit) should be regarded not as a basal Colorado transgressive sand but as a Mannville unit deposited prior to the maximum break.Sampling of microfauna from successively younger units of the Middle and Upper Mannville indicates a shift away from normal marine environments and towards increasingly brackish depositional conditions. This shift may have resulted from the development of embayment-like conditions during the withdrawal of the Clearwater sea, as well as from increases in fluvial drainage during the late stages of Mannville deposition.
The effects of aluminum on Picearubens:factorial experiments using sand culture
Authors: McCanny Stephen J. , Lechowicz Martin J. , Shipley Bill , Hendershot William H.
Published: June 2009

We used sand culture to examine the effects of aluminum (Al3+) on gas exchange and growth in 1+0 Picearubens Sarg. seedlings. Growth solutions were prepared to match the elemental concentrations of the soil solutions in a declining Abiesbalsamea (L.) Mill.–P. rubens stand. In our first experiment, we used a four-way factorial design to examine the interactions between Al, pH, nutrients, and CO2. All plants were nitrogen deficient. Photosynthetic rate and instantaneous water-use efficiency both declined at 250 μmol•L−1 Al, as did the root/shoot ratio of the seedlings. Plant weight, however, was not significantly affected by the 10-fold increase in Al solution concentration. These results were robust across a range of experimental conditions, suggesting that other aspects of soil acidification, such as NO3 fertilization in N deficient soils, could counteract the toxic effects of Al. In a second experiment, we examined the effects of subtoxic concentrations of Al at two levels of nutrient cation availability. Unlike in a previous study, cation fertilization affected neither gas exchange nor growth. While the decreases in root/shoot ratio and growth were expected at 250 μmol•L−1 Al, the peak in growth rates for intermediate concentrations of Al (25–100 μmol•L−1) was not. The latter result was interpreted in light of the positive effects that low concentrations of Al are known to have on other species.
White spruce site index in relation to soil, understory vegetation, and foliar nutrients
Authors: Wang G. Geoff
Published: June 2009

The relationships between site index and measures of soil, understory vegetation, and foliar nutrients were examined using data from 102 white spruce (Piceaglauca (Moench) Voss) stands in the Sub-boreal Spruce zone of British Columbia. Compared with soil physical properties (adjusted.R2 = 0.54), soil nutrient properties (adjusted.R2 = 0.29) were poor predictors of white spruce site index. The best soil model, using depth of major rooting zone, total nitrogen, and slope as predictors, explained 60% of the total variance in site index. The best understory vegetation model, using frequencies of soil-moisture and nitrogen indicator species groups as predictors, explained 53% of the total variance in site index. The best foliar nutrient model, using foliar phosphorus and sulphur as predictors, explained 64% of the total variance in site index. Adding variables from understory vegetation, foliar nutrients, or both into the best soil model significantly improved site index prediction. The resultant models explained up to 83% of the total variance in site index. When stands were stratified according to groundwater influence, regression models developed for three delineated strata were significantly improved compared with unstratified models. Based on practical consideration, four regression models were considered for predicting white spruce site index. Independent testing indicated that the stratified model, which used only soil variables as predictors, predicted white spruce site index with 79% of the estimate errors within 2 m in the study area.
Phosphorus cycling in a hardwood forest in the Adirondack Mountains, New York
Authors: Zhang Yimin , Mitchell Myron J.
Published: June 2009

Total P was monitored at Huntington Forest in the Adirondack Mountains of New York from June 1986 to May 1987. Total P in precipitation from an adjacent open site was compared with throughfall, stemflow, and soil solutions collected from a hardwood stand dominated by American beech (Fagusgrandifolia Ehrh.) and sugar maple (Acersaccharum Marsh.). Total P concentrations in bulk precipitation were very similar throughout the year (4.95 μmol•L−1 in rain versus 4.93 μmol•L−1 in snow). Total P concentration was lower in throughfall than in bulk precipitation, and P in growing season bulk throughfall (1.79 μmol•L−1) was greater than that in the dormant season (1.00 μmol•L−1). Total P concentrations in both throughfall and stemflow were higher under beech than maple. Phosphorus concentrations in soil solutions decreased as water passed through the soil profile. Phosphorus was tightly retained in this ecosystem except for a small loss via drainage water during spring snowmelt.
Throughfall chemistry of ponderosa pine exposed to wet and dry acidic deposition, drought, ozone, and nitric acid
Authors: Fenn Mark E. , Poth Mark A. , Bytnerowicz Andrzej , Riechers George H.
Published: June 2009

Throughfall chemistry was studied in ponderosa pine (Pinusponderosa Laws.) seedlings exposed to wet and dry acidic deposition, ozone (O3), drought, and nitric acid (HNO3) in open-top chambers in the Sierra Nevada of California from 1988 to 1990. Seven acid rain events (pH 3.5, 4.4, and 5.3) occurred during each growing season. Acidity of the simulated rain treatments had little effect on net throughfall fluxes except for greater net SO42− content in throughfall of the pH 3.5 treatment. Electrical conductivity and NO3− and NH4+ content of throughfall were significantly higher in the NF150 treatment (1.5 × ambient O3) than in the charcoal-filtered (CF) or non-charcoal-filtered (NF) treatments in all 3 years. Throughfall acidity in the NF150 treatment was higher than that in the CF or NF treatment during the last 2 years of the study. Effects of the NF150 treatment on throughfall chemistry were attributed primarily to deposition of HNO3 from higher N oxides produced by the air-supplied O3 generator. The concentration of HNO3 in the NF150 chambers was typical for forests in the United States, but only 26% as high as that at Tanbark Flat in the Los Angeles Air Basin. We estimated that co-generated HNO3 contributed 0.5% of the total N in current-year foliage of seedlings in the NF150 treatment. Irrigation treatment did not have a significant effect on throughfall chemistry except for a slightly greater decrease in throughfall pH in the well-watered plants compared with the drought-stressed plants in the pH 5.3 rain treatment in 1989. Absolute values for electrical conductivity and NO3− and NH4+ content in throughfall tended to be higher with greater particulate dry deposition (45–55% removed versus 90% removed by filtration) in 1989 and 1990, but differences were not statistically significant.
Molecular cytogenetics of Icelandic birch species: physical mapping by in situ hybridization and rDNA polymorphism
Authors: Anamthawat-Jonsson Kesara , Heslop-Harrison J.S.
Published: June 2009

The physical mapping of genes can reveal the organization of a genome and identify relationships of plant species, especially where they are involved in interspecific hybridization and polyploidy. Here we determine the chromosomal locations of the major ribosomal gene family (18S-5.8S-26S rDNA) by fluorescent in situ hybridization in two Icelandic birch species, Betulapubescens Ehrh. and Betulanana L. In the tetraploid birch (B. pubescens), the rDNA was localized on four major and two minor sites, while the diploid dwarf birch (B. nana) had four major sites. The major loci in both species were in nucleolus organizer regions, close to the centromeres of a pair of metacentric and a pair of sub-metacentric chromosomes. The dispersed interphase in situ hybridization pattern showed gene expression at all major sites. The two additional loci in B. pubescens, when detected, appeared to be sub-telomeric and inactive at interphase. Southern analysis of rDNA showed considerable restriction fragment length polymorphism in B. pubescens. Some polymorphism may reflect gene flow among populations and between the two co-existing birch species. The understanding of genome relationships, gene introgression, and evolution of birch species will be important to the breeding programmes steered towards environmental conservation and forestry.
A MULTI-CRITERIA PROCEDURE FOR THE USER INTERFACE COMPONENTS LAYOUT PROBLEM
Authors: PEER S. K. , SHARMA DINESH K. , RAVINDRANATH K. , NAIDU M. M.
Published: June 2009

The multi-criteria facilities layout problem can be formulated as a quadratic assignment model that can handle multiple qualitative and quantitative factors in the objective function. Some studies have shown that the techniques and tools of facilities layout problems can equally be applied for the layout design of user interface components in human-computer interface. This paper presents an alternate approach, which handles multiple qualitative and quantitative factors in a different manner separately in the objective function to obtain the initial layouts. The proposed approach also consists of a layout procedure, in which the pair of facilities with the least composite criterion value has been selected to be placed far apart in the layout to generate an initial layout in the construction procedure. The results of the proposed approach are compared with that of an existing approach which handles a number of qualitative and quantitative factors in the same manner as in the objective function to obtain the initial layouts for the example task of the user interface components layout problem under consideration.
Spike Transmission Delay at the Calyx of Held In Vivo: Rate Dependence, Phenomenological Modeling, and Relevance for Sound Localization
Authors: Tolnai Sandra , Englitz Bernhard , Scholbach Jonathan , Jost Jürgen , Rübsamen Rudolf
Published: June 2009

Transmission at central synapses exhibits rapid changes in response amplitude under different patterns of stimulation. Whether the delay associated with the transmission of action potentials is similarly modifiable is important for temporally precise computations. We address this question at the calyx of Held of the medial nucleus of the trapezoid body (MNTB) in Mongolian gerbils in vivo using extracellular recordings. Here the pre- and postsynaptic activity can be observed simultaneously, allowing the definition of an action potential transmission delay (ATD) from the pre- to the postsynaptic side. We find the ATD to increase as a function of spike rate (10–40%). The temporal dynamics of the ATD increase exhibit an exponential shape with activity-dependent time constants (∼15–25 ms). Recovery dynamics of ATD were mono- (20–70 ms) or biexponential with fast (3–20 ms) and slow time constants (50–500 ms). Using a phenomenological model to capture ATD dynamics, we estimated ΔATD = 5–30 μs per transmitted action potential. Using vocalizations and cage noise stimuli, we confirm that substantial changes in ATD occur in natural situations. Because the ATD changes cover the behaviorally relevant range of interaural time differences in gerbils, these results could provide constraints for models of sound localization.
Effects of Chronic PPAR‐Agonist Treatment on Cardiac Structure and Function, Blood Pressure, and Kidney in Healthy Sprague‐Dawley Rats
Authors: Blasi Eileen R. , Heyen Jonathan , Hemkens Michelle , McHarg Aileen , Ecelbarger Carolyn M. , Tiwari Swasti
Published: June 2009

PPAR‐γ agonists have been associated with heart failure (HF) in diabetic patients. These incidences have been reported mostly in patient populations who were at high risk for HF or had pre‐existing impaired cardiovascular function. However, whether there are similar effects of these agents in subjects with no or reduced cardiovascular pathophysiology is not clear. In this study, the effects of chronic treatment with PD168, a potent peroxisome proliferator activated receptor (PPAR) subtype‐γ agonist with weak activity at PPAR‐α, and rosiglitazone (RGZ), a less potent PPAR‐γ agonist with no PPAR‐α activity, were evaluated on the cardiovascular‐renal system in healthy male Sprague‐Dawley (SD) rats by serial echocardiography and radiotelemetry. Rats were treated with vehicle (VEH), PD168, @ 10 or 50 mg/kg⋅bw/day (PD‐10 or PD‐50, resp.) or RGZ @ 180 mg/kg⋅bw/day for 28 days (n = 10/group). Relative to VEH, RGZ, and both doses of PD168 resulted in a significant fall in blood pressure. Furthermore, RGZ and PD168 increased plasma volume (% increase from baseline) 18%, 22%, and 48% for RGZ, PD‐10, and PD‐50, respectively. PD168 and RGZ significantly increased urinary aldosterone excretion and heart‐to‐body weight ratio relative to VEH. In addition, PD168 significantly decreased (10–16%) cardiac ejection fraction (EF) and increased left ventricular area (LVA) in systole (s) and diastole (d) in PD‐10 and ‐50 rats. RGZ significantly increased LVAd; however, it did not affect EF relative to VEH. In conclusion, chronic PPAR‐γ therapy may predispose the cardiorenal system to a potential sequela of structural and/or functional changes that may be deleterious with regard to morbidity and mortality.
Crystallographically Oriented Nanorods and Nanowires of RF‐Magnetron‐Sputtered Zinc Oxide
Authors: Srivastava A. K. , Chakraborty B. R. , Chandra S.
Published: June 2009

The formation of nanoscaled one‐dimensional structure constituting the thin films of ZnO via a RF magnetron sputtering process is demonstrated. A detailed analysis of these films has been carried out by exploiting the techniques of ellipsometry, scanning and transmission electron microscopy (SEM, TEM), high‐resolution TEM, and scanning tunneling microscopy (STM). The importance of substrate materials due to the nanomorphologies as rods and wires on the substrates as amorphous quartz and silicon, respectively, has been elucidated. It has been exhibited that these fascinating nano‐objects (rods, wires) are grown directionally along c‐axis of hexagonal lattice of ZnO. The nucleation and growth mechanisms of these nano‐objects have been discussed to interpret the present results.
Role of PPARα in the Control of Torpor through FGF21‐NPY Pathway: From Circadian Clock to Seasonal Change in Mammals
Authors: Ishida Norio
Published: June 2009

In nature, hibernating animals encounter fasting, cold temperature and short day seasonally. Torpor is a state of decreased physiological activity in an animal, usually characterized by a reduced body temperature and rate of metabolism to adapt such a severe environment. Ablation of the central clock synchronizer, the suprachiasmatic nucleus in brain, abolishes torpor, a hibernation‐like state, implicating the circadian clock involved in this seasonal change. Biologists knows well the energy source of daily heterotherms/hibernators changed from glucose to lipids in winter. Here we review several lines of evidence of a master transcriptional regulator in lipid catabolism, PPARα, in the control of torpor through FGF21‐NPY pathway. This indicate the importance of circadian—and photoperiod—regulation of PPARα to tell seasons in our body.
Cell Therapy in Chagas Disease
Authors: Campos de Carvalho Antonio C. , Goldenberg Regina C. S. , Jelicks Linda A. , Soares Milena B. P. , dos Santos Ricardo Ribeiro , Spray David C. , Tanowitz Herbert B.
Published: June 2009

Chagas disease which is caused by the parasiteTrypanosoma cruziis an important cause of cardiomyopathy in Latin America. In later stages chagasic cardiomyopathy is associated with congestive heart failure which is often refractory to medical therapy. In these individuals heart transplantation has been attempted. However, this procedure is fraught with many problems attributable to the surgery and the postsurgical administration of immunosuppressive drugs. Studies in mice suggest that the transplantation of bone-marrow-derived cells ameliorates the inflammation and fibrosis in the heart associated with this infection. Cardiac magnetic resonance imaging reveals that bone marrow transplantation ameliorates the infection induced right ventricular enlargement. On the basis of these animal studies the safety of autologous bone marrow transplantation has been assessed in patients with chagasic end-stage heart disease. The initial results are encouraging and more studies need to be performed.
Accurate Antenna Pattern Modeling for Phased Array Antennas in SAR Applications—Demonstration on TerraSAR-X
Authors: Bachmann Markus , Schwerdt Marco , Bräutigam Benjamin
Published: June 2009

The high flexibility and tight accuracy requirements of today's spaceborne synthetic aperture radar (SAR) systems require innovative technologies to calibrate and process the SAR images. To perform accurate pattern correction during SAR processing, an Antenna Model is used to derive the multitude of different antenna beams generated by active antenna steering. The application of such an Antenna Model could be successfully demonstrated for the TerraSAR-X mission, launched in 2007. The methodology and the results of the inorbit verification with an achieved accuracy of better than  dB is reviewed in this paper in detail showing its outstanding accuracy.
Role of Socioeconomic Indicators on Development of Obesity from a Life Course Perspective
Authors: Salonen Minna K. , Kajantie Eero , Osmond Clive , Forsén Tom , Ylihärsilä Hilkka , Paile-Hyvärinen Maria , Barker David J. P. , Eriksson Johan G.
Published: June 2009

Aims. Development of obesity is modified by several factors, including socioeconomic ones. We studied the importance of socioeconomic indicators on the development of obesity from a life course perspective.Methods. 2003 people born 1934–1944 in Helsinki, Finland, participated in clinical examinations in 2001–2004. Obesity was defined as body mass index (BMI)>30 kg/m2.Results. Prevalence of obesity was 22.3% in men and 27.2% in women. Lower educational attainment and lower adult social class were associated with higher BMI in both men (P=.03andP<.01) and women (P<.001andP=.01). Childhood social class was inversely associated with BMI only in men (P<.001); lower household income was associated with higher BMI in women only (P<.001). Those men belonging to the lowest childhood social class had higher risk of being obese than those of the highest childhood social class (OR 1.8 (95% CI: 1.0–3.1)). Household income was the strongest predictor of obesity among women.Conclusion. Overweight and obesity are inversely associated with socioeconomic status. Men seem to be more susceptible to adverse childhood socioeconomic circumstances than women, while adult socioeconomic indicators were more strongly associated with obesity in women.
Optimum Maintenance Policy of a Periodically Inspected System under Imperfect Repair
Authors: Badía F. G. , Berrade M. D.
Published: June 2009

This paper deals with the maintenance policy of a system subject to periodical inspections aimed at detecting the occurrence of failures. After the first failure, the system undergoes an imperfect repair that brings the system back to the operating condition while the th failure is followed by a perfect repair restoring the unit to an as-good-as-new condition. The limiting average availability as well as the minimum cost policy are discussed.
Blind Deblurring Reconstruction Technique with Applications in PET Imaging
Authors: Li Heng , Mawlawi Osama R. , Zhu Ronald X. , Zheng Yibin
Published: June 2009

We developed an empirical PET model taking into account system blurring and a blind iterative reconstruction scheme that estimates both the actual image and the point spread function of the system. Reconstruction images of high quality can be acquired by using the proposed reconstruction technique for both synthetic and experimental data. In the synthetic data study, the algorithm reduces image blurring and preserves the edges without introducing extra artifacts. The localized measurement shows that the performance of the reconstruction image improved by up to 100%. In experimental data studies, the contrast and quality of reconstruction is substantially improved. The proposed method shows promise in tumor localization and quantification.
Vascular and Neural Dysfunctions in Obese Zucker Rats: Effect of AVE7688
Authors: Davidson Eric P. , Coppey Lawrence J. , Kleinschmidt Travis L. , Oltman Christine L. , Yorek Mark A.
Published: June 2009

The purpose of this study was to determine whether AVE7688 a drug that inhibits both angiotensin converting enzyme and neutral endopeptidase activity protects vascular and nerve functions in an animal model of metabolic syndrome. Obese Zucker rats at 20 weeks of age were treated for 12 weeks with AVE7688. Vasodilation in epineurial arterioles was measured by videomicroscopy and nerve conduction velocity was measured following electrical stimulation. Treatment with AVE7688 improved vascular relaxation in response to acetylcholine and motor and sensory nerve conduction velocity. In obese Zucker rats superoxide levels and nitrotyrosine staining were elevated in the aorta and treatment corrected both conditions. Obese Zucker rats were hypoalgesic in response to a thermal stimulus and demonstrated signs of impaired tactile response and both conditions were significantly improved with treatment. Even though obese Zucker rats are normoglycemic vascular and neural dysfunctions develop with age and can be improved by treatment with AVE7688.
Segmentation of Myocardial Boundaries in Tagged Cardiac MRI Using Active Contours: A Gradient‐Based Approach Integrating Texture Analysis
Authors: Histace Aymeric , Matuszewski Bogdan , Zhang Yan
Published: June 2009

The noninvasive assessment of cardiac function is of first importance for the diagnosis of cardiovascular diseases. Among all medical scanners only a few enables radiologists to evaluate the local cardiac motion. Tagged cardiac MRI is one of them. This protocol generates on Short‐Axis (SA) sequences a dark grid which is deformed in accordance with the cardiac motion. Tracking the grid allows specialists a local estimation of cardiac geometrical parameters within myocardium. The work described in this paper aims to automate the myocardial contours detection in order to optimize the detection and the tracking of the grid of tags within myocardium. The method we have developed for endocardial and epicardial contours detection is based on the use of texture analysis and active contours models. Texture analysis allows us to define energy maps more efficient than those usually used in active contours methods where attractor is often based on gradient and which were useless in our case of study, for quality of tagged cardiac MRI is very poor.
Estimating the Broad‐Sense Heritability of Early Growth of Cowpea
Authors: Xu Nicole W. , Xu Shizhong , Ehlers Jeff
Published: June 2009

Cowpea is an important tropical crop. It provides a large proportion of the food resource for the African human population and their livestock. The yield and quality of cowpea have been dramatically improved through traditional breeding strategies for the past few decades. However, reports of heritability estimates for early growth of cowpea are rare. We designed a simple experiment to estimate the broad‐sense heritability of early growth. We randomly selected 15 cowpea varieties among a total of 5000 cowpea accessions maintained in the cowpea breeding facility at the University of California, Riverside to examine the genetic determination of early growth of cowpea (measured as the height at day five after seeding). The estimated broad‐sense heritability on the individual plant basis is 0.2190. However, the corresponding estimate on the plant mean basis (average of four plants) is 0.5198, which is very high for a quantitative trait. The high heritability may explain why traditional breeding for cowpea growth is so effective. Since the design of experiment and method of data analysis are novel, this report can serve as an educational note for students in the area of quantitative genetics and plant breeding.
Longitudinal Association of PCSK9 Sequence Variations With Low-Density Lipoprotein Cholesterol Levels
Authors: Huang Chiang-Ching , Fornage Myriam , Lloyd-Jones Donald M. , Wei Gina S. , Boerwinkle Eric , Liu Kiang
Published: June 2009

Background—

Mutations of
PCSK9
are associated cross-sectionally with plasma low-density lipoprotein cholesterol (LDL-C) levels, but little is known about their longitudinal association with LDL-C levels from young adulthood to middle age.

Methods and Results—

We investigated the associations of 6
PCSK9
variants with LDL-C over 20 years in 1750 blacks and 1828 whites from the Coronary Artery Risk Development In Young Adults study. Generalized estimating equations were used to assess longitudinal differences in LDL-C levels between genotype categories. For blacks, LDL-C levels at age 18 were significantly lower (
P
<0.001) among those with 3 genetic variants (L253F, C679X, and Y142X; 81.5 mg/dL) and A443T (95.5 mg/dL) compared with noncarriers (109.6 mg/dL). The difference in LDL-C levels from noncarriers tended to widen for those with the 3 variants only, by 0.24 mg/dL per year of age (
P
=0.14). For whites with the R46L variant, compared with noncarriers, LDL-C levels at age 18 were significantly lower (84.4 mg/dL versus 100.9 mg/dL;
P
<0.001), and the increase in LDL-C with age was similar to noncarriers. The 3 genetic variants and the A443T variant in black men were associated with lower carotid intima-media thickness and lower prevalence of coronary calcification measured at ages 38 to 50.

Conclusions—

Our results suggest that participants with several genetic variants of
PCSK9
have persistently lower serum LDL-C levels than noncarriers from ages 18 to 50. Such long-term reduction in LDL-C levels is associated with reduced subclinical atherosclerosis burden in black men.