bluuebunny/crossref_metadata_2025 huggingface dataset:
Batchawana Bay, Lake Superior: late Quaternary sedimentary fill and paleomagnetic record
Authors: Mothersill John S.
Published: June 2010

The lake-bottom sediments of the shelf area of Batchawana Bay are composed of sands, and the basinal sediments grade from silts to coarse-grained clay basin ward. There is a significant relationship of decreasing mean grain size to increasing water depth for the sediments of the basinal areas. Although the sediments of Batchawana Bay would appear to be formed by the variable mixing of sand and clay, hydraulic action probably removed the clay end member and ultimately deposited it in the lake proper.Grains of magnetic minerals deposited on a lake bottom tend to align in the direction of the Earth's magnetic field at the time of deposition, imparting a remanent magnetic direction to the sediments. The late Holocene sedimentary sequence of Batchawana Bay provides a record of the secular changes of the Earth's magnetic field. "Type" paleodeclination and paleoinclination logs plotted against time can be utilized to date the sedimentary sequence of Batchawana Bay. This paleomagnetic time scale indicates that glacial outwash and varve deposition continued for approximately 600 years after glacial retreat from the lake basin to about 8700 years BP.
Chemostratigraphy and origin of the late Archean siderite–pyrite-rich Helen Iron Formation, Michipicoten belt, Canada
Authors: Goodwin A. M. , Thode H. G. , Chou C.-L. , Karkhansis S. N.
Published: June 2010

The 2.7 Ga old Helen Iron Formation (HIF) with its uniquely large siderite–Pyrite orebody conformably overlies chemically altered rhyolite–dacite pyroclastic rocks, including an ottrelite-bearing alteration pipe, the product of exhalative venting in freshly accumulated pyroclastics. HIF, in turn, is conformably overlain by pillowed mafic lava flows.HIF internal stratigraphy is conformable from lower massive siderite–sulfide through middle sulfidic, carbonaceous chert, to upper magnetitic chert. Major- and trace-element and carbon- and sulfur-isotope data demonstrate cyclic fluctuations in chemical precipitation from early chemically complex to later chemically "simple" components.HIF development is attributed to seawater-charged volcanic exhalations in a transitory subaqueous cauldron subsidence basin. Volcanic exhalations contained (1) the main chemical components of HIF; (2) nutrients that triggered intense bacterial activity, the principal low-Eh-inducing agent; and (3) acidic components (e.g., HCI, HF), the principal low-pH-inducing agent. HIF carbonates (predominantly siderite) and sulfides (mainly pyrite) are of marine carbonate and marine sulfate origin, respectively. Organic activity was a vital catalyst in carbonate–sulfide precipitation. HIF is notably deficient in base and noble metals, thereby indicating low circulation–exhalation temperatures, in sharp contrast to contemporary hot, metal-rich geothermal brines at modern spreading ridge axes. This transient subaqueous late Archean volcanic environment, then, was unique in scale but not in kind.
Radiocarbon age of rock-boring Hiatella arctica (Linné) and postglacial sea-level change at Cow Head, Newfoundland
Authors: Brookes Ian A. , Stevens Robert K.
Published: June 2010

Carbonate bedrock surfaces recently exposed at Cow Head, Newfoundland (50°14′N, 57°35′W) are densely riddled with boreholes of Hiatella arctica (Linné), many of which are occupied by subfossil specimens of this bivalve as well as with vermiform burrows of a sponge (? Cliona sp.). A radiocarbon date of 8250 ± 320 years BP (GSC-3433) on several Hiatella valves from the burrows gives the age of a sea-level stand at 8 m asl at the locality, during which penecontemporaneous surf erosion or beach gravel deposition led to the demise of the shells. Other unoccupied cavities in longer exposed bedrock outcrops on Cow Head are contrasted in form and distribution with those of Hiatella and are argued to be boreholes of another marine invertebrate, not positively identified.
Stable-isotope paleoclimate records for southern Ontario, Canada: comparison of results from marl and wood
Authors: Edwards T. W. D. , Fritz P.
Published: June 2010

Profiles of δ18O in two marl cores from southern Ontario, Canada, are compared in detail with the records of meteoric water isotopic composition and photosynthetic humidity obtained from previous isotopic studies using wood cellulose at Brampton, Ontario. By accounting for the inferred changes in meteoric water composition and temperature, the changes in the oxygen-isotope content of the marl arising from fluctuations in the evaporative enrichment of the lakewater can be estimated. The resulting synthetic profiles of relative evaporative enrichment from both marl cores exhibit strong correspondence to the photosynthetic humidity profile generated from the studies at Brampton, which substantiates the importance of evaporation in the water budgets of these two lakes. A striking analogy exists between the isotopic evaporative enrichment response of such lakewaters and that of the waters in terrestrial plants; both of the marl lakes approach close to isotopic steady state during the summer season, when carbonate precipitation occurs.The results of these studies strengthen the basis for paleoclimatic interpretations suggested in previous reports. Most notably, the marl data yield further evidence for relatively dry conditions in southern Ontario during the early part of the Hypsithermal interval, at a time that coincides with maximum eastward extension of prairie in the midwest United States.
Spatial and temporal patterns of suspended-sediment yield in the Saskatchewan River basin
Authors: Ashmore P. E. , Day T. J.
Published: June 2010

Long-term suspended-sediment concentration and load records are available for 23 Water Survey of Canada sediment-monitoring stations in the Saskatchewan River basin, where the drainage areas range from 10 to over 300 000 km2. Mean annual sediment yield is greatest in the western Alberta Plains along the Oldman and Red Deer rivers (over 100 t km−2 year−1) and tends to increase downstream along the North and South Saskatchewan rivers until major reservoirs in Saskatchewan intervene. Average sediment concentration shows a pattern of variation similar to that of yield. Temporal aspects of suspended-sediment transport vary along the drainage network. The range and skewness of the yield–duration and concentration–duration curves are greater in the intermediate-size basins close to the Rocky Mountains and in two small basins with Prairie sources than they are in the large Prairie streams with mountain sources and the glacier-fed upper North Saskatchewan River. Similarly, infrequent flows transport a larger proportion of the annual load in the smaller Foothills and western Plains basins than in the large Prairie streams because of differences in drainage area and discharge regime.
Xenoliths in a mafic dyke at Popes Harbour, Nova Scotia: implications for the basement to the Meguma Group
Authors: Owen J. V. , Greenough J. D. , Hy Charlotte , Ruffman Alan
Published: June 2010

A recently recognized series of northwest-trending mafic dykes cuts the Cambro-Ordovician Meguma Group along the eastern shore of Nova Scotia. Some of the dykes contain gneissic and (meta)plutonic xenoliths interpreted here as including fragments of the basement to the Meguma Group.Most of the gneissic xenoliths in the dyke exposed at Popes Harbour are sillimanite- and (or) kyanite-bearing quartz-poor metapelites and garnet + orthopyroxene-bearing tonalitic rock. Other enclaves include amphibolite, quartzite, gabbro, granite–granodiorite, and granitic pegmatite. Textural features suggest that the earliest paragneissic assemblage included poikiloblastic garnet (XFe = 0.55–0.65, XMg = 0.05–0.30, XCa = 0.02–0.16, XMn = 0.02–0.16), biotite, kyanite and (or) sillimanite, oligoclase, and quartz. Subsequent recrystallization at higher temperature and (or) lower pressure conditions is suggested by the replacement of kyanite by sillimanite. Mineral core composition data indicate early metamorphic conditions of ~450–600 MPa (gt–Al2SiO5–pl–qz and gt–opx–pi–qz barometers) and at least 600 °C (gt–bi and opx–gt thermometers), which lie close to the kyanite–sillimanite boundary and do not clearly distinguish the kyanite- and sillimanite-forming events. Other relatively high temperature and (or) lower pressure texturally overprinting assemblages include, in the pelites, (i) sapphirine (XMg = 0.75), spinel (XMg = 0.45–0.65), corundum, and rutile (all with anatectic(?) calcic plagioclase or ternary feldspar rims); and (ii) calcic rims on plagioclase and pyrope-rich overgrowths on garnet in both pelitic and tonalitic gneiss.The polymict assemblage of xenoliths in the Popes Harbour dyke testifies to the heterogeneity of the basement to the Meguma Group.
Geochemical changes accompanying the mylonitization of diverse rock types from the Grenville Front zone, eastern Labrador
Authors: Owen J. V.
Published: June 2010

The relationship between mineralogy and bulk composition was examined in mylonites developed in a variety of rock types from the Grenville Front zone of eastern Labrador. Mylonites developed from olivine-, pyroxene-, and (or) amphibole-bearing protoliths are the most altered, typically being enriched in K2O and volatiles and depleted in CaO compared with the protolith. Bulk-compositional modification was accompanied by the formation of almandine-rich garnet and (or) relatively ferruginous hornblende in medium-grade (epidote–amphibolite to lower amphibolite facies) mylonites derived from both mafic and quartzo-feldspathic rocks. Protoliths containing biotite as the principal or sole Fe–Mg phase were the least altered during deformation. Apart from variations in Ti content, biotite in mylonitic assemblages derived from these rocks is compositionally similar to that in the low-strain precursor.Bulk-compositional changes recognized in narrow mylonite zones appear to have occurred in Grenvillian tectonites developed on a regional scale.
An ammonite zonation for the Lower Jurassic of Canada and the United States: the Pliensbachian
Authors: Smith Paul L. , Tipper Howard W. , Taylor David G. , Guex Jean
Published: June 2010

This is the first in a series of papers intended to establish a Lower Jurassic ammonite zonation that takes into account the biostratigraphic and biogeographic peculiarities of the North American succession. Its development has been spurred by the need for high-resolution correlation between allochthonous terranes and the need for a standard to which microfossil sequences may be coupled.In North America the lower boundary of the Pliensbachian is drawn above the last echioceratids. The lower Pliensbachian is divided into, in ascending order, the Imlayi, Whiteavesi, and Freboldi zones; the upper Pliensbachian, into the Kunae and Carlottense zones. The Fannin Bay section in the Queen Charlotte Islands is designated the stratotype for the Whiteavesi, Freboldi, and Kunae zones; ideal stratotypes for the Imlayi and Carlottense zones are not presently known. Reference sections former illustrating the faunal associations that characterize all the zones are designated in western Nevada (the Sunrise Formation), northeastern Oregon (the Hurwal Formation), and northern British Columbia (the Spatsizi Group and Takwahoni Formation).The Polymorphitidae and Eoderoceratidae furnish the most important zonal indicators for the lower Pliensbachian; Oxynoticeratidae (Fanninoceras) and Hildoceratidae, for the upper Pliensbachian. Pseudoskirroceras imlayi and Acanthopleuroceras whiteavesi are described as new species. The presence of amaltheids in the northern parts of the allochthonous terranes permits a comparison with the northwest European succession at this level. Furthermore, the association in North America of typically east Pacific, Mediterranean, and northeast Asian species, as well as northwest European forms, emphasizes the critical importance of the North American Pliensbachian in achieving global correlations.
The Calvin 28 structure: evidence for impact origin
Authors: Milstein Randall L.
Published: June 2010

The Calvin 28 structure is an isolated, nearly circular subsurface structure of Late Ordovician age in southwestern Michigan. The structure is defined by 107 test wells, is 7.24 km in diameter, and consists of a central dome, an annular depression, and an encircling anticlinal rim.Seismic and geophysical well-log data confirm an intricate system of faults and structural derangement exists within the structure. Deformation decreases with depth and distance from the structure. United States Geological Survey topographic maps and aerial imagery show the structure is reflected as a surface topographic rise controlling local drainage.Igneous or diapiric intrusion and solution collapse are rejected as possible origins for Calvin 28 on the basis of stratigraphic, structural, and geophysical evidence. A volcanic origin is rejected because of an absence of igneous material.Although shock-metamorphic features are unidentified, microbreccias are found in deep wells that penetrate the structure. Morphology and structural parameters suggest an impact origin.
Significance of a Cambrian date from galena lead-isotope data for the stratiform Cottonbelt deposit in the Monashee Complex, southeastern British Columbia
Authors: Höy T. , Godwin C. I.
Published: June 2010

The Cottonbelt deposit is a large stratiform lead–zinc–magnetite layer within cover rocks of Frenchman Cap dome in the Monashee Complex in southeastern British Columbia. Lead-isotope analyses of galena samples from the deposit plot close to the Cambrian–Hadrynian boundary on lead-isotope ratio diagrams and are similar to analyses of Early Cambrian stratiform deposits in the Anvil Camp in the Yukon Territory. These data suggest that the Cottonbelt deposit and host succession are Cambrian in age, in contrast to other interpretations that suggest considerably older ages for the cover succession of Frenchman Cap dome. These cover rocks, therefore, are considered calcareous and pelitic facies of lower Paleozoic shelf rocks now exposed in the Kootenay Arc to the southeast and the Selkirk Mountains to the east.
Paleomagnetism of the Callander Complex and the Cambrian apparent polar wander path for North America
Authors: Symons D. T. A. , Chiasson A. D.
Published: June 2010

The 7 km2 circular Callander alkaline complex was emplaced into anorthositic and granitic gneisses of the Grenville Province in the Canadian Shield about 575 ± 5 Ma ago at the start of the Cambrian. The complex has not been subsequently metamorphosed or tilted. Detailed alternating-field and thermal step demagnetization of 252 specimens from 29 sites led to the identification of a characteristic A magnetization component with a direction of D = 82.2°, I = 82.7° (α95 = 3.1°, k = 83, N = 26 sites) in 5 sites of mesocratic to leucocratic syenite from the core of the complex, in 5 sites of fenitized host rock from its aureole, and in 16 sites of lamprophyre from radiating dikes. Isothermal remanent-magnetization tests show that the A component is retained by both magnetite and hematite in a complete spectrum of domain sizes. A reversals test suggests and a contact test shows the A component to be primary. Its pole position at 46.3°S, 121.4°E(dp = 5.9°, dm = 6.1°) does not fall on published but poorly defined Cambrian apparent polar wander paths, leading to speculation on an alternative Cambrian path.
An exceptionally preserved parasitic arthropod, Heymonsicambria taylori n.sp. (Arthropoda incertae sedis: Pentastomida), from Cambrian – Ordovician boundary beds of Newfoundland, Canada
Authors: Walossek Dieter , Repetski John E. , Müller Klaus J.
Published: June 2010

A three-dimensionally and completely preserved phosphatized microfossil has been found in Cambrian–Ordovician boundary bed limestones of the Green Point Formation at Green Point, western Newfoundland, Canada. It represents a new form of larvae, previously described by D. Walossek and K.J. Müller from Upper Cambrian anthraconitic limestones ("Orsten"). These authors identified the fossils as instars of marine stem-group representatives of the "tongue worms," Pentastomida. Pentastomida are parasites that today infest various land tetrapods and are presumed to represent one of the closest extant relatives of the Euarthropoda. This new fossil possesses remarkably well-preserved trunk limb vestigia and anal region. It is another example of exceptional three-dimensionally preserved, phosphatized fossils of the Orsten type that is no longer spatiotemporally restricted to the Upper Cambrian of Sweden.
Effects of measurement errors on an individual tree-based growth projection system
Authors: Gertner George Z. , Dzialowy Paul J.
Published: June 2010

Systematic and random measurement errors were placed on the input variables of a distance-independent individual tree-based growth and mortality projection model to study how sensitive the system was to measurement error. The study was conducted in three parts. First, the effects of systematic measurement errors on individual model components of the growth projection were investigated. Second, systematic errors were placed on the input variables of the growth projection system and the performance of the overall system was observed. Third, a Monte Carlo study was performed to examine the effects of random measurement errors of varying magnitude on the projection system estimates. Overall, the projection system was most sensitive to measurement errors in site index. Measurement errors in diameter at breast height were only critical when projecting basal area, but were not critical when projecting number of trees. The system was insensitive to errors in crown ratio.
Allowable cut effects without even flow constraints
Authors: Binkley Clark S.
Published: June 2010

The allowable cut effect in harvest scheduling problems stems from the constraints which link harvests between periods. Historically, allowable cut effects have been associated with even flow constraints, but this is only one example of a more general situation. This paper describes two generic problems where allowable cut effects arise without any flow constraint. Allowable cut effects are a general part of the harvest scheduling problem. Valid economic analysis of forest management programs requires the inclusion of the positive or negative incomes associated with them.
A simulation study assessing the effect of sampling for predictor variable values on estimates of yield
Authors: Smith James L. , Burkhart Harold E.
Published: June 2010

In a study aimed at investigating the effects of sampling for predictor variable values on yield estimates, independent simple random and stratified random samples of stand density and tree height were drawn from simulated pine plantations containing nine strata. Sample outcomes were substituted into a selected yield function to produce estimates of mean yield. Stratifying by both site index and numbers of trees per unit area improved the precision of the yield estimates by 2/3 over simple random samples. Total sample size had no effect on the magnitude of the improvements in the yield estimate. Site index was the more important of the two stratifying variables, but synergistic effects between the two characteristics for stratification were found. Estimating the mean yield with the average of the sample plot yields is recommended over using the alternative of using the mean values of the independent variables. Averaging the sample plot yields produced superior mean yield estimates with less bias and with smaller average error sizes especially when simple random samples were drawn.
First-year regeneration in upland hardwoods after two levels of residue removal
Authors: Mann L. K.
Published: June 2010

The effects of whole-tree removal versus conventional sawlog harvest on 1 st-year regeneration in an upland mixed hardwood site were compared, and sprouting dynamics of species and stump size classes were described. Average sprout production for stumps sampled was greater after conventional harvest: stumps produced taller, denser, and more abundant sprouts. Although sample sizes were small, maximum heights of stump sprouts of Quercusprinus L., Quercusvelutina Lam., and Acerrubrum L. were greater on the conventionally harvested area, and sprouts of Liriodendrontulipifera L. and Oxydendrumarboreum (L.) DC. averaged taller after residue removal. However, most species produced more seedlings after residue removal. Differences were related to greater site disturbance with whole-tree harvest. Number of sprouts and biomass per stump showed a binomial-shaped distribution in relation to stump diameter across both treatments, with a maximum at about 30 cm. Biomass of grape (Vitis spp.) was least following whole-tree removal, but this may be related to site quality or the small size of the study area. Regression estimates of sprout dry weight as a function of height were used to estimate sprout production. Conservative estimates of total stump sprout biomass, excluding foliage, 1year after whole-tree removal averaged 433 kg/ha and after conventional harvest averaged 679 kg/ha.
Factors influencing initial sprouting of red alder
Authors: Harrington Constance A.
Published: June 2010

Two studies were established to investigate factors influencing sprouting of red alder (Alnusrubra Bong.). In the first study, 4-year-old planted trees were cut at five stump heights (0, 10, 30, 50, and 70 cm) during 4 months of the year (January, May, July, and September). The percent of stumps surviving was greatest with cuts in January at 30 cm or higher; survival was least with 0- and 10-cm cuts during July and September. In the second study, 29 natural stands varying in age from 1 to 32 years were cut in February. Sprouting was most vigorous and consistent in very young stands. Few stumps sprouted in the oldest stands; in addition, the older stands had fewer sprouts per stump and the sprouts were shorter. Stumps with a level surface had the greatest mortality and were least likely to sprout; stumps with the cut surface facing south or west had the least mortality and were most likely to sprout. Based on the results from both studies, specific cutting practices are recommended to achieve different management objectives.
Classification and comparison of upland hardwood and conifer ecosystems of the Cyrus H. McCormick Experimental Forest, upper Michigan
Authors: Pregitzer Kurt S. , Barnes Burton V.
Published: June 2010

An ecological method of forest site classification was used to classify and map local ecosystems of the Cyrus H. McCormick Experimental Forest near Marquette in the upper peninsula of Michigan, U.S.A. The field method of site classification was effective in distinguishing 11 ecosystem units that differed markedly in their vegetation as well as in their topographic and soil properties. Each ecosystem repeatedly occurred in a characteristic topographic position within the landscape. Ecosystems were identified in the field using combinations of biophysical properties such as slope, aspect, soil texture, soil drainage, and forest composition. Ecological species groups, groups of indicator plants, were especially helpful in distinguishing ecosystems in the field. Soils of ecosystems identified using the ecological method of classification differed significantly in their physical and chemical properties, and principal component analysis and numerical clustering confirmed that soils of the 11 upland ecosystems were different. Discriminant analyses combined with calculations of the probability of misclassification were used to compare the relative merit of physical factors (topographic and soil factors) and vegetation in classifying ecosystems. The simultaneous use of topographic, soil, and vegetal factors proved most efficient in classifying the upland ecosystems of the McCormick Experimental Forest.
Forcing additivity of biomass tables: some empirical results
Authors: Cunia T. , Briggs R. D.
Published: June 2010

Three methods for insuring the additivity of biomass tables are described and their application to a sample of trees illustrated. The advantages and drawbacks of each method are identified and the results obtained compared with each other. All three methods yield biomass tables that are not significantly different from each other (at least for the sample data used), but their estimated precision and conditions of applicability are different. At least one of the methods can be applied to the cases where the weights to use in the least squares regression procedure may differ from one to the next tree component, when sample data of some component are missing from some sample trees and when nonlinear seem better than linear regression functions.
Impact of ozone and sulfur dioxide on net photosynthesis of hybrid poplar cuttings
Authors: Jensen K. F. , Noble R. D.
Published: June 2010

Softwood cuttings of hybrid poplar clone No. 207 (Populusdeltoides Bartr. × Populustrichocarpa Torry and Gray) were fumigated with either charcoal-filtered air (control), 0.5 ppm SO2, or 0.5 ppm SO2 + 0.25 ppm O3 for 12 h each day for 3 weeks. The net photosynthetic rate and CO2 compensation point were then measured in a closed-loop gas assimilation system with an infrared gas analyzer. Net photosynthesis was measured at light intensities of 430 and 730 μE•m−2•s−1 (photosynthetically active radiation) and in CO2 concentrations of 300, 500, and 1000 ppm. Net photosynthesis increased with an increase in light intensity and CO2 concentration but was significantly reduced by the SO2 + O3 treatment. The leaves were classified into five groups on the basis of visible injury. There were no significant differences in the net photosynthetic rates among uninjured leaves in the three fumigation treatments. However, analysis of the data from the SO2 + O3 treatment, which separated the leaves into injury classes, showed that the CO2 – injury class interaction was significant. At 300 ppm CO2, there were no significant differences in the net photosynthetic rates among the five injury classes. At 500 and 1000 ppm CO2, there were significant differences in the photosynthetic rates between leaves without visible injury and those with injury. Photosynthesis in the injured leaves may have been suppressed by an increase in the respiration rate and a decrease in the photosynthetic area. The increased respiration rate is suggested by the CO2 compensation point data that was significantly higher in all of the fumigated leaves. There were no significant differences in the chlorophyll content of the leaves from the three treatment groups.
Sublimation of occidentalol, a sesquiterpene alcohol, from eastern white cedar (Thujaoccidentalis) in a drying kiln
Authors: Roy D. N. , Konar Samir K. , Purdy John R.
Published: June 2010

A substance which condensed on the cooling coils of a Westair recirculating kiln while drying eastern white cedar (Thujaoccidentalis L.) was identified as natural (+)-occidentalol. This sesquiterpene alcohol was found in remarkably pure form (over 90%) and is more likely to appear when drying freshly cut heartwood. It was removed from the coils by washing them with alcohol. Standard bioassays against Fomesannosus (Fr.) Cke (Heterobasidionannosum (Fr.) Bref.), Lenzitestrabea Pers. ex Fries, and Chaetomiumglobosum Kunze ex Fries showed no activity for occidentalol; the loss of this substance would not reduce the decay resistance of cedar wood. Examination of wood extracts showed that the sesquiterpene alcohol cedrol, previously mentioned in the literature as an extractive of this wood, was not found either in the sublimate from the kiln or in the wood.
Seasonal variations in the uptake of [32P]phosphate ions by excised ectomycorrhizae and lateral roots of Abies balsamea
Authors: Langlois C. G. , Fortin J. A.
Published: June 2010

The absorption of phosphate ions by long lateral nonmycorrhizal roots and by four of the most prevalent types of ectomycorrhizae of Abiesbalsamea was followed over one season of growth. For each experiment, the excised roots were bathed for 2.5 h in a buffered nutrient solution containing 100 μg•L−1 of KH2PO4 and 100 μCi•L−1 (1 Ci = 37 GBq) of KH232PO4. The results indicate that the rates of absorption of the different types of balsam fir root apices varied during the season and differed from one type to another. The surface of absorption appeared to have an effect on the amount of phosphate ions taken up from the solution. The rates of absorption measured invitro, seemed to reflect the seasonal absorption potential for phosphate ions by balsam fir roots invivo. It was clearly demonstrated that the most intensive rates of uptake occurred in mid-August immediately after bud set. The possibility that the absorption of phosphate ions is controlled by internal demand and is related to the translocation of carbohydrates is discussed.
Promoting bud development in balsam fir Christmas trees with 6-benzylaminopurine
Authors: Little C. H. A.
Published: June 2010

The entire crown of variously fertilized, unsheared Abiesbalsamea (L.) Mill. trees was sprayed once or twice weekly for 2, 4, or 8 weeks with an aqueous solution of 0 or 600 mg 6-benzylaminopurine (BAP) L−1 containing 1.5% dimethyl sulfoxide, 13.5% methanol, and 0.1% Tween 20, starting at different times during the period of shoot elongation. In the year of application, BAP inhibited the elongation of the current-year shoot, increased the number of lateral buds formed on this shoot, and induced lammas growth. Both BAP and the carrier solution caused some phytotoxicity in current-year needles. Responses to BAP treatment varied markedly with genotype, whorl position, and time of application, and decreased with mineral deficiency, and decreasing BAP dosage. After overwintering, many of the BAP-induced lateral buds elongated, resulting in an increased number of shoots, hence in a denser crown.
Calculating Thornthwaite and Mather's actual evapotranspiration using an approximating function
Authors: Pastor J. , Post W. M.
Published: June 2010

A simple negative exponential function is presented which relates soil water storage to a maximum storage value (field capacity) and accumulated potential water loss. This formula summarizes 10 tables from Thornthwaite and Mather (Publications in Climatology, 10: 183–311, 1957) needed to calculate actual evapotranspiration (AET). Comparisons are presented for values predicted by this formula and Thornthwaite and Mather's tabulated values.
STATISTICAL PROPERTIES OF INTENSITY FLUCTUATION OF SATURATION LASER MODEL DRIVEN BY CROSS-CORRELATED ADDITIVE AND MULTIPLICATIVE NOISES
Authors: ZHU PING , ZHU YI JIE
Published: June 2010

Statistical properties of the intensity fluctuation of a saturation laser model driven by cross-correlation additive and multiplicative noises are investigated. Using the Novikov theorem and the projection operator method, we obtain the analytic expressions of the stationary probability distribution Pst(I), the relaxation time Tc, and the normalized variance λ2(0) of the system. By numerical computation, we discussed the effects of the cross-correlation strength λ, the cross-correlation time τ, the quantum noise intensity D, and the pump noise intensity Q for the fluctuation of the laser intensity. Above the threshold, λ weakens the stationary probability distribution, speeds up the startup velocity of the laser system from start status to steady work, and attenuates the stability of laser intensity output; however, τ strengthens the stationary probability distribution and strengths the stability of laser intensity output; when λ < 0, τ speeds up the startup; on the contrast, when λ > 0, τ slows down the startup. D and Q make the relaxation time exhibit extremum structure, that is, the startup time possesses the least values. At the threshold, τ cannot generate the effects for the saturation laser system, λ expedites the startup velocity and weakens the stability of laser intensity output. Below threshold, the effects of λ and τ not only relate to λ and τ, but also relate to other parameters of the system.
DISTRIBUTION OF PURE STATES IN SHORT-RANGE SPIN GLASSES
Authors: NEWMAN C. M. , STEIN D. L.
Published: June 2010

We review the structure of the spin glass phase in the infinite-range Sherrington–Kirkpatrick model and the short-range Edwards–Anderson (EA) model. While the former is now believed to be understood, the nature of the latter remains unresolved. However, considerable insight can be gained through the use of the metastate, a mathematical construct that provides a probability measure on the space of all thermodynamic states. Using tools provided by the metastate construct, possibilities for the nature of the organization of pure states in short-range spin glasses can be considerably narrowed. We review the concept of the "ordinary" metastate, and also newer ideas on the excitation metastate, which has been recently used to prove existence of only a single pair of ground states in the EA Ising model in the half-plane. We close by presenting a new result, using metastate methods, on the number of mixed states allowed in the EA model.
SYNCHRONIZATION IN A MODEL OF INTERACTING INFERIOR OLIVE CELLS WITH TIME-DELAYED COUPLING
Authors: ZAKHAROV D. G. , NEKORKIN V. I.
Published: June 2010

The influence of coupling time delay on synchronization processes is studied within the framework of a model describing the dynamics of two inferior olive cells coupled electronically through gap-junctions surrounded by synaptic inhibitory terminals that block these couplings. It was found that different types of synchronous behavior exist in the system, depending on parameters, and that even small changes of coupling time delay may change a dynamic regime to another one. This may be the transition between the regimes of different synchronization types, spike time binding, nonsynchronous behavior or the regime of activity suppression of an inferior olive cell.
GLOBAL DYNAMICS IN NETWORKS OF 1D ELEMENTS WITH TIME DELAYED MEAN FIELD COUPLING SUBJECT TO NOISE: SYNCHRONIZATION THRESHOLD, MULTISTABILITY AND HYSTERESIS
Authors: POTOTSKY A. , JANSON N.
Published: June 2010

We determine the boundary of the synchronization domain of a large number of one-dimensional continuous stochastic elements with time delayed nonhomogeneous mean-field coupling. The exact location of the synchronization threshold is shown to be a solution of the boundary value problem (BVP) which was derived from the linearized Fokker–Planck equation. Here the synchronization threshold is found by solving this BVP using the continuation technique (AUTO). Approximate analytics is obtained using expansion into eigenfunctions of the stationary Fokker–Planck operator. Multistability and hysteresis are demonstrated for the case of bistable elements with a polynomial potential.
A GRAPH-BASED ALGORITHM FOR MINING MULTI-LEVEL PATTERNS IN GENOMIC DATA
Authors: LAM WINNIE W. M. , CHAN KEITH C. C. , CHIU DAVID K. Y. , WONG ANDREW K. C.
Published: June 2010

Comparative genomics is concerned with the study of genome structure and function of different species. It can provide useful information for the derivation of evolutionary and functional relationships between genomes. Previous work on genome comparison focuses mainly on comparing the entire genomes for visualization without further analysis. As many interesting patterns may exist between genomes and may lead to the discovering of functional gene segments (groups of genes), we propose an algorithm called Multi-Level Genome Comparison Algorithm (MGC) that can be used to facilitate the analysis of genomes at multi-levels during the comparison process to discover sequential and regional consistency in gene segments. Different genomes may have common sub-sequences that differ from each other due to mutations, lateral gene transfers, gene rearrangements, etc., and these sub-sequences are usually not easily identified. Not all the genes can have a perfect one-to-one matching with each other. It is quite possible for one-to-many or many-to-many ambiguous relationships to exist between them. To perform the tasks effectively, MGC takes such ambiguity into consideration during genome comparison by representing genomes in a graph and then make use of a graph mining algorithm called the Multi-Level Attributed Graph Mining Algorithm (MAGMA) to build a hierarchical multi-level graph structure to facilitate genome comparison. To determine the effectiveness of these proposed algorithms, experiments were performed using intra- and inter-species of Microbial genomes. The results show that the proposed algorithms are able to discover multiple level matching patterns that show the similarities and dissimilarities among different genomes, in addition to confirming the specific role of the genes in the genomes.
Polylogarithmic independence fools
AC
0
circuits
Authors: Braverman Mark
Published: June 2010

We prove that poly-sized
AC
0
circuits cannot distinguish a polylogarithmically independent distribution from the uniform one. This settles the 1990 conjecture by Linial and Nisan [1990]. The only prior progress on the problem was by Bazzi [2007], who showed that
O
(log
2
n
)-independent distributions fool poly-size DNF formulas. [Razborov 2008] has later given a much simpler proof for Bazzi's theorem.
Software development and crunch time; and more
Authors: Ortega Ruben , Guzdial Mark , Reed Daniel
Published: June 2010

The
Communications
Web site, http://cacm.acm.org, features more than a dozen bloggers in the BLOG@CACM community. In each issue of
Communications
, we'll publish selected posts or excerpts.

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Follow us on Twitter at http://twitter.com/blogCACM

Ruben Ortega discusses developers and crunch time; Mark Guzdial considers the impact of open source practices on computing education; and Daniel Reed writes about the technological shift from computational paucity to computational plethora.
Work life in the robotic age
Authors: Borenstein Jason
Published: June 2010

Technological change results in changes in expectations, in this case affecting the workplace.
Computer graphics for all
Authors: Igarashi Takeo
Published: June 2010

Interactive computer graphics would rival word-processing and presentation programs for everyday communications.
Commonsense understanding of concurrency
Authors: Lewandowski Gary , Bouvier Dennis J. , Chen Tzu-Yi , McCartney Robert , Sanders Kate , Simon Beth , VanDeGrift Tammy
Published: June 2010

Innate understanding of concurrency helps beginners solve CS problems with multiple processes executing at the same time.
x86-TSO
Authors: Sewell Peter , Sarkar Susmit , Owens Scott , Nardelli Francesco Zappa , Myreen Magnus O.
Published: June 2010

Exploiting the multiprocessors that have recently become ubiquitous requires high-performance and reliable concurrent systems code, for concurrent data structures, operating system kernels, synchronization libraries, compilers, and so on. However, concurrent programming, which is always challenging, is made much more so by two problems. First, real multiprocessors typically do not provide the sequentially consistent memory that is assumed by most work on semantics and verification. Instead, they have relaxed memory models, varying in subtle ways between processor families, in which different hardware threads may have only loosely consistent views of a shared memory. Second, the public vendor architectures, supposedly specifying what programmers can rely on, are often in ambiguous informal prose (a particularly poor medium for loose specifications), leading to widespread confusion.

In this paper we focus on x86 processors. We review several recent Intel and AMD specifications, showing that all contain serious ambiguities, some are arguably too weak to program above, and some are simply unsound with respect to actual hardware. We present a new
x86-TSO
programmer's model that, to the best of our knowledge, suffers from none of these problems. It is mathematically precise (rigorously defined in HOL4) but can be presented as an intuitive abstract machine which should be widely accessible to working programmers. We illustrate how this can be used to reason about the correctness of a Linux spinlock implementation and describe a general theory of data-race freedom for x86-TSO. This should put x86 multiprocessor system building on a more solid foundation; it should also provide a basis for future work on verification of such systems.
ERP
Authors: Romero Jorge A. , Menon Nirup , Banker Rajiv D. , Anderson Mark
Published: June 2010

Introduction

Most large companies have adopted some form of enterprise resource planning (ERP) system. A survey of IT executives in the U.S. showed that ERP was the second most important key category for investment. In many cases, the implementation of an ERP system was a long and expensive ordeal that involved extensive restructuring of businesses and reengineering of processes.

While the potential benefits of ERP have been extolled frequently and much has been written about individual company experiences, only limited evidence has been produced that implementation of ERP does, on average, lead to enhanced performance. To the best of our knowledge, this is the first industry analysis on ERP because previous work has been limited to case studies and industry cross-sectional analyses.

Several research studies have validated that IT provides productivity and profitability advantages. However, questions remain because it is not clear whether advantages from IT contribute, and to what degree they might contribute, to operational efficiency and profitability. For example, if the same IT is implemented by all firms in an industry, will industry profits from IT disappear? Due to the fact that for many years large companies developed their information systems independently, there have been limited opportunities to evaluate the implementation of similar IT infrastructure across companies. This study seeks to extend prior work by performing a longitudinal study of implementation of ERP systems in a specific industry.

According to Porter, each industry is affected by new information technology in different ways and drawing general conclusions about how new IT affects firms across industries would be a mistake. The oil and gas industry was selected because ERP plays a major role in standardizing business processes in this industry. In this role, ERP helps firms link global operations and supply chains. Also, a commodity-product industry, like the oil and gas industry, helps us control for other influences that may have affected the performance of oil and gas companies during the study period. The ERP adopting firms are those that adopted SAP.

This research applies a new methodological approach toward understanding ERP implementation because rather than looking at ordinary measures of firm performance, we look at strategic performance measures (SPM) that can only be utilized if one delves into data that is not found on the financial statements. This is the first study that shows the sources of profitability after an ERP implementation, and will help managers understand the strategic and managerial implications of ERP implementations. Our analysis compares performance changes of ERP adopting firms versus non-adopting firms over a fifteen-year period (1990--2005), which is the period when this industry was being transformed by increased use of technology in the oil and gas industry. Therefore, we see how the implementation of ERP affected firm performance during this period in relation to non-adopting firms.
Creating the experience economy in e-commerce
Authors: Chang Wei-Lun , Yuan Soe-Tsyr , Hsu Carol W.
Published: June 2010

Introduction

Advances in information technology together with the forces of globalization have accelerated the growth of service industries. In 2003, the OECD reported that service industries now account for over 60% of both employment and the gross domestic product (GDP) of OECD member countries. The U.S Bureau of Labor Statistics (BLS) has forecast strong employment growth in the American service sector between 2004 and 2014. Although service industries are expanding, Gilmore and Pine argue that, the growing commoditisation of services offered has gradually transformed the competition for market share from focusing on the quality of services to the creation of memorable experiences. As a consequence, the competitive position of a firm now depends to a large extent on its ability to generate impressive experiences through innovative delivery channels.

In this article, we adopt Gilmore and Pine's view that the economic value of the experience economy lies in co-producing the staging experiences via customer participation and connection. Furthermore, we suggest that current technologies and the growth of the Internet have both enabled and strengthened the opportunities for experience-oriented offerings beyond limitations of time and place. In following sections, we first describe the current practice of experience economy in electronic commerce. Taking the iCare health care service as an example, we demonstrate how collaborative pricing over the Internet can further provide added-value to the production of experiences offered in the electronic marketplace.
IT programs in high schools
Authors: Dennis Alan R. , Duffy Thomas M. , Cakir Hasan
Published: June 2010

Introduction

Student enrollment in college computer science (CS) and information technology (IT) programs are in a downward trend in most developed countries. At the same time, the U.S. Bureau of Labor and their counterparts in other countries forecast an increased need for skilled CS/IT graduates.

To reverse the downwards trend in college level CS/IT enrollment, ACM launched the Computer Science Teachers Association (csta.acm.org), whose mission is to "directly and passionately" advocate for computer science education in the high school.

One major initiative is to develop a comprehensive computer science curriculum that educates high school students and informs them about the profession because a major factor in the enrollment decline is a lack of knowledge about possible CS/IT careers. In this article, we examine one CS/IT program (the Cisco Networking Academy that has been offered in high schools since 1978) to understand what lessons we can draw for other CS/IT high school initiatives.