bluuebunny/crossref_metadata_2025 huggingface dataset:
Seed Storage and Germination Under Northern Hardwood Forests
Authors: Marquis David A.
Published: May 2008

The species, quantities, and germination of tree seed stored in the forest floor beneath five northern hardwood stands in Pennsylvania were determined by counting seed found in blocks of forest floor material and running germination tests on them, by burying seed in soil organic layers and observing germination and storage, and by sowing seed on natural seedbeds and observing germination over several years. Quantities of seed in excess of 1 million per acre (2.5 million per hectare) were found to be common, the number of seed of a particular species depending on the number of seed-bearing trees of that species in the overstory and on the length of time seed of that species will remain viable in the forest floor. Sugar maple, eastern hemlock, and American beech normally germinate the year after seed dispersal and do not remain viable in the forest floor. Black cherry, white ash, yellow poplar, red maple, and birch normally germinate over a period of several years after dispersal; and storage in the forest floor for 2 to 5 years is common. Pin cherry seed remain viable in the forest floor for long periods, and large quantities of seed may still be present 30 years or more after pin cherry trees have died out of the overstory.
A Linear Programming Model for Multiple-use Planning
Authors: Leuschner William A. , Porter John R. , Reynolds Marion R. , Burkhart Harold E.
Published: May 2008

Multiple-use planning is useful in matching forest production possibilities and social desires. A linear programming model for multiple-use planning is presented. Planning is approached as a set of production objectives which have a set of management activities to help achieve them and a set of constraints which limit the management activities. Timber yield is the objective function and other multiple-use objectives are stated as constraints. Production can be increased by certain management activities, but these activities are limited by budget, cutting, and other technical constraints. Size of the area cut is the choice variable and the solution is tied to 21.6-acre (8.74-ha) grid cells thereby identifying the geographical location of management and production activities. The model was tested on a planning unit and sensitivity analyses were performed on the initial optimal solution. These indicated that on this planning unit, there is a wide range of production alternatives which will not affect other multiple-use production possibilities and that production is sensitive to budget changes.
A Technique for Tagging Tree Seed to Facilitate Identification or Recovery in Nursery and Field Experiments
Authors: Fraser James W.
Published: May 2008

A technique for marking tree seeds to facilitate their identification or recovery in nursery and field experiments is described; the method consists of coating the seeds with latex and day-fluorescent pigments. The coating, tested on black spruce (Piceamariana [Mill.] B.S.P.) seed, made possible +95% recovery of seed buried 1–6 cm deep in natural seedbeds for 22 months. Germination from freshly coated seed was significantly slower and lower than from untreated seeds, but after 4, 10, 16, and 22 months storage, germination from coated seed was the same as from untreated seed, i.e., +98%.
A Technique to Eliminate or Control Extraneous Nutrient Materials in Wood Decay Studies
Authors: Magasi Laszlo P.
Published: May 2008

A method to study wood decay in pure culture, with the effects of extraneous nutrient materials eliminated, is described and tested for uniformity. The feeder strip, supported by two glass rods (5 mm diam) above wet sand in a petri plate, is inoculated with the fungus. Up to six wood blocks of known weight are placed on the feeder strip after the fungus is established and incubated. Weight loss is determined at the end of the incubation period. The method is adaptable for specialized studies of wood decay when it is desired to minimize or control the factor of extraneous nutrients.
The Effect of Some Monohydroxybenzoic and Dihydroxybenzoic Acids as Auxin Synergists on Rooting Softwood Cuttings of Basswood (Tiliaamericana L.) Under Mist
Authors: Morsink W. A. G. , Smith V. G.
Published: May 2008

Softwood cuttings of one clone and one juvenile population of basswood were rooted under intermittent mist, using a 2-min basal dip of indolebutyric acid (IBA) at concentrations of 1000, 5000, and 10 000 parts per million (ppm) in combination with one of salicylic acid, p-hydroxybenzoic acid, 3,5-, 2,5-, and 2,6-dihydroxybenzoic acids at concentrations of 5, 50, and 100 ppm. None of the phenolic compounds showed any root-promoting effect when used singly. In combination with IBA, 2,5-dihydroxybenzoic acid showed a root-promoting effect when applied to cuttings of the population but not for cuttings of the single clone.A root-promoting effect at certain of the higher concentrations of the rest of the phenols when combined with IBA could not clearly be distinguished from sample variation. IBA alone or in combination with any of the phenols had a much smaller root-promoting effect when applied to the cuttings of the single clone.
Use of Small Plots Can Overestimate Upper Limits to Basal Area and Biomass
Authors: Smith J. Harry G.
Published: May 2008

Measurements of cross-sectional area outside bark at breast height in a spruce – subalpine fir forest were studied to determine the effects of plot size on minimum and maximum amounts of basal area sampled per unit area. Assuming a good relationship between basal area and biomass of trees, the need for careful interpretation of stand weight estimates on small plots is illustrated.
New application of a polynomial curve to plot volume estimation
Authors: Zakrzewski W.T. , Ter-Mikaelian M.
Published: May 2008

This paper presents a new method of plot volume estimation using a limited sample of heights. It requires measurement of all diameters in the plot and a limited number of height measurements per plot within a plot-specific diameter class predefined by the method. It also requires a diameter-based description of tree form. The method utilizes a polynomial curve to relate heights and diameters, but does not provide information on the plot height structure in the form of a traditional height–diameter curve. The approach was examined using data from north-central Ontario jack pine (Pinusbanksiana Lamb.) stands. The developed method of stand volume estimation is precise and unbiased with respect to height measurements; it reduces laborious height measurements compared with traditional methods utilizing a height–diameter curve.
Anthropogenic and natural disturbance and patterns of mortality in a mixed conifer forest in California
Authors: Savage Melissa
Published: May 2008

Anthropogenic and natural disturbances have been implicated in recent mortality episodes in montane forests. While the role of natural disturbance in patterning forest ecosystems has been widely explored in recent decades, the agency of human influence is less well understood. In this paper, stand structure analysis is used to characterize patterns of mortality in a montane mixed conifer forest in southern California subject to multiple influences, both anthropogenic and natural, including fire suppression, air pollution, drought, competition, and insect infestation. While it is difficult to separate the contribution of any one of these factors to tree death, because there have been cumulative and synchronous disturbances, successional trends can be identified. Anthropogenic influences appear to abet the effects of natural disturbance in enhancing the shift from early successional pines to species that tolerate stresses such as drought, fire suppression, or competition that result from increased stand density, or a combination of such stresses.
Diurnal variation in heat tolerance and heat shock protein expression in black spruce (Piceamariana)
Authors: Colombo Stephen John , Timmer Victor Robbert , Colclough Melanie Louise , Blumwald Eduardo
Published: May 2008

Experiments were conducted using black spruce (Piceamariana (Mill.) B.S.P.) seedlings to evaluate diurnal variability in heat tolerance of roots and shoots and in levels of root heat shock proteins (HSPs). Shoot heat tolerance was significantly lower in the morning than in the afternoon. Similarly, root systems exposed to high temperatures in the morning suffered significantly more damage than those exposed in the afternoon. Root HSPs were identified using an antibody specific for the constitutive HSP73 and inducible HSP72. Both the constitutive levels of root HSPs and the levels of root HSPs following heat shock varied diurnally, and in different patterns for different protein fractions. The levels of soluble and nuclear root HSP72/73 were enhanced by heat shock, both in the morning and afternoon. In comparison, HSP levels in the root mitochondrial protein fractions increased after heat shock in the morning, but decreased after heat shock in the afternoon. HSPs in the root microsomal protein fraction declined following both morning and afternoon heat shock. The higher afternoon levels of root heat tolerance were associated with the greater constitutive levels of HSP73 in the mitochondrial and microsomal root protein fractions in the afternoon. To examine the effects of the shoot on diurnal variation in root system heat tolerance, root heat damage was compared between seedlings with intact shoots versus seedlings with shoots excised either 4–6 h prior to, or immediately before, heat treatment. Regardless of time of day, root systems died when shoots were excised and root systems were treated with high temperatures. In contrast, shoot excision or root heating alone resulted in no root mortality.
Water content measurement in forest soils and decayed wood using time domain reflectometry
Authors: Gray Andrew N. , Spies Thomas A.
Published: May 2008

The use of time domain reflectometry to measure moisture content in forest soils and woody debris was evaluated. Calibrations were developed on undisturbed soil cores from four forest stands and on point samples from decayed logs. An algorithm for interpreting irregularly shaped traces generated by the reflectometer was also developed. Two different calibration equations were needed to estimate volumetric moisture content at the four sites, but commonly implicated soil characteristics (organic matter content, bulk density, and soil texture) could not fully account for the differences between calibrations. The calibrations differed from previously published calibrations for mineral and organic soils. Estimation of moisture content in decayed wood was possible with a single significant regression. The standard errors of estimate for volumetric water content were less than 0.02 m3 m−3 for the soil calibrations and just over 0.06 m3 m−3 for the decayed wood calibration. We found we could reliably interpret most traces from field samples using an automated algorithm, but had to use a modified algorithm for one of the sites. This study suggests a need to calibrate time domain reflectometry measurements for individual forest sites and advises caution when using systems that have preprogrammed calibration and trace analysis routines.
A simple method for estimating the number of seed cones on individual black spruce
Authors: Caron G.-É. , Fleming R.A.
Published: May 2008

A procedure for quickly and conveniently predicting the number of seed cones on individual black spruce (Piceamariana (Mill.) B.S.P.) trees in a seed production area is proposed. As one approaches a tree to be sampled, a quick visual estimate is made of the tree's seed cones. When this estimate suggests that the number of seed cones on the tree, N, is less than 13, it is faster to count them. But when N > 13, it is faster to measure the position, LbPOS, of the branch bearing the lowest seed cone, and to estimate the tree's seed-cone yield by taking the antilogarithm of 1.08 + ln(LbPOS - 0.125) and subtracting 1.0 from the result. The age of the tree at the time the seed cones were produced was incorporated in this model as an additional explanatory variable. A time study showed that on heavily bearing trees, a full count could take 80 times as long as this alternative procedure. The drawback to this alternative is the inaccuracy introduced by taking estimates rather than full counts. When this alternative procedure was applied to the sampled trees, the average relative bias, mean square error, and mean relative deviation in estimating N were 0.270, 16 100 seed cones2, and 0.605 per tree, respectively. Although this study suggests the cutoff number of cones to be counted at N = 13, one may prefer spending more time to gather more accurate estimates. For this, a table provides the corresponding time and accuracy statistics for various other possible choices of the maximum number of seed cones at which full counts can be conducted.
Incorporating intertree competition into an ecosystem model
Authors: Korol R.L. , Running S.W. , Milner K.S.
Published: May 2008

Current research suggests that projected climate change may influence the growth of individual trees. Therefore, growth and yield models that can respond to potential changes in climate must be developed, TREE-BGC, a variant of the ecosystem process model FOREST-BGC, calculates the cycling of carbon, water, and nitrogen in and through forested ecosystems. TREE-BGC allocates stand-level estimates of photosynthesis to "each tree using a competition algorithm that incorporates tree height, relative radiation-use efficiency, and absorbed photosynthetically active radiation, TREE-BGC simulated the growth of trees grown in a dense and an open stand of interior Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) near Kamloops, B.C. The competition algorithm dynamically allocated stand estimates of photosynthesis to individual trees, and the trees were grown using an allometric relationship between biomass increment and height and diameter increment. Asymptotic height growth and the changes in the height–diameter relationship with competition were also incorporated in the model algorithms. Sapwood and phloem volume were used to calculate maintenance respiration. Predicted reductions in diameter growth with stand density were similar to those observed in the study stands. Although the carbon balance of individual trees was not tested, simulated tree diameter increments and height increments were correlated with the actual measurements of tree diameter increment (r2 = 0.89) and tree height increment (r2 = 0.78) for the 5-year period (n = 352). Although the model did not work well with trees that had diameters <5 cm, the model would be appropriate for a user who required an accuracy of ± 0.03 m3•ha−1 for volume, ± 0.02 m2•ha−1 for basal area, or ± 0.4 m for tree height over a 5-year period.
Effect of plant moisture stress and application surface on uptake and translocation of triclopyr with organosilicone surfactant in red maple seedlings
Authors: Bollig J.J. , Seiler J.R. , Zedaker S.M. , Thompson J.W. , Lucero D.
Published: May 2008

This study investigated the effect of plant moisture stress and surface of application on the absorption, translocation, and "rainfastness" (short-term ability to retain herbicide) of organosilicone-adjuvated (adjuvant added) [14C]triclopyr amine on greenhouse-grown, 4-month-old red maple (Acerrubrum L.) seedlings. Xylem water potentials were −1.6 and −0.9 MPa and leaf conductances were 0.07 and 0.13 cm s−1 for the stressed and control seedlings, respectively. At 2 h, rainfastness was 13% less for stressed seedlings. Uptake increased with time, and by 72 h no effect of moisture stress treatment was apparent. Abaxial absorption into living leaf tissue was 57% greater at 72 h than was adaxial absorption, but application surface did not significantly affect translocation. Plant moisture stress did, however, reduce translocation of herbicide into the shoots and roots. Organosilicone surfactants may enhance long-term triclopyr uptake in water-stressed seedlings, but do not appear to facilitate translocation in stressed seedlings. Plant moisture status, therefore, should continue to be a concern when scheduling herbicide applications.
Gas exchange of 20-year-old black spruce families displaying a genotype × environment interaction in growth rate
Authors: Johnsen Kurt H. , Major John E.
Published: May 2008

Gas exchange and xylem water potential were measured on 20-year-old black spruce (Piceamariana (Mill.) B.S.P) trees from four full-sib families from a 7 × 7 diallel. These families constitute a 2 parent × 2 parent factorial breeding structure. One female parent (59) produced families that have displayed high productivity on three plantation sites, whereas the other female parent (63) produced families that had high growth rates on two of the sites but not on the third, least productive, site. In 1991 (a hot, dry year) measurements were obtained from trees at two sites; in 1992 (a cool, wet year) measurements were obtained from only one site. Gas exchange was measured on detached branches cut from the upper third of the crown; measurements were initiated within 2 min from cutting. In 1991, daytime xylem water potential, predawn xylem water potential, net photosynthesis (Pn), and needle conductance (gwv) were all lower in trees growing on the least productive site (2) than in trees growing on the most productive site (3), indicating that trees on site 2 were under greater water stress than those on site 3. Progeny of female 59 displayed higher Pn than progeny of female 63 over both years of contrasting rainfall and on both the wetter and drier sites during the first year. However, progeny of the two female parents did not differ with respect to gwv in either year nor on either site during the first year. The genetic variation in Pn/gwv, observed over sites and years, is positively related to growth rate only on the dry site. Thus, the genotype × environment interaction in growth appears to be due to relatively stable genetic differences in Pn. We hypothesize that water stress on the dry site reduces Pn below a threshold value at which point genetic variation in Pn impacts on productivity and results in genetic variation in growth rate. Furthermore, we hypothesize that on the wet site carbon gain per unit leaf area is not as limiting to growth rate; thus, the observed genetic differences in Pn do not influence genetic rankings in growth rate.
Analysis of intraspecific nuclear DNA content variation in Gleditsiatriacanthos by flow cytometry
Authors: Wake CM. , Schaefer P.R. , Jost L.K. , Evenson D.P.
Published: May 2008

Honeylocust trees (Gleditsiatriacanthos L.) are distributed across a wide range of climatic and edaphic conditions, demonstrating considerable variation in cold, drought, and salinity tolerances. In many angiosperm species, an evolutionary change in nuclear DNA content accompanies colonization into more stressful environments. Fresh leaf nuclei were isolated from 22 honeylocust sources from across the species' native range, mixed with trout red blood cells, stained with propidium iodide, and their DNA content was measured by flow cytometry. According to DNA stainability of the trout red blood cells, leaf nuclei had a DNA content of 1.72 ± 0.02 pg (mean ± SD). Variation in DNA content among the sources was not significant (p < 0.05), suggesting that adaptive evolutionary changes in honeylocust are not evident in increasing or decreasing amounts of leaf nuclear DNA content.
Practical analysis of factorial experiments in forestry
Authors: Stehman S.V. , Meredith M.P.
Published: May 2008

Factorial designs are among the most frequently employed for arranging treatments in forestry experiments. Yet researchers often fail either to recognize the factorial treatment structure or to take full advantage of the structure for interpreting treatment effects. The analysis of factorial experiments should focus on comparisons of means of research interest specified by the investigator. Reliance on default options of computing packages or routine application of multiple comparison procedures often fails to address research hypotheses directly. A two-step strategy for the analysis of factorial experiments entails a check for interaction followed by estimation of either main effects or simple effects. This strategy emphasizes sensible mean comparisons through estimation of contrasts and their standard errors. The strategy also applies to the analysis of factorial experiments in which unequal replication or empty cells complicate the analysis. We summarize a practical approach for use by forest scientists and applied statisticians consulting with such scientists so that they may analyze and interpret their experiments more effectively.
Using the β-binomial distribution to characterize forest health
Authors: Zarnoch S.J. , Anderson R.L. , Sheffield R.M.
Published: May 2008

The β–binomial distribution is suggested as a model for describing and analyzing the dichotomous data obtained from programs monitoring the health of forests in the United States. Maximum likelihood estimation of the parameters is given as well as asymptotic likelihood ratio tests. The procedure is illustrated with data on dogwood anthracnose infection (caused by Disculadestructive¡) in the southeastern United States. The parameter estimates have important biological interpretation, and tests of hypotheses are more meaningful than traditional statistical analyses. The value of a modeling approach to dichotomous data analysis is emphasized.
Juniperusoccidentalis juvenile foliage: advantages and disadvantages for a stress-tolerant, invasive conifer
Authors: Miller P.M. , Eddleman L.E. , Miller J.M.
Published: May 2008

Physiological processes for juvenile and adult foliage of Juniperusoccidentalis Hook. were compared to evaluate the advantages and disadvantages of juvenile foliage for a stress-tolerant, invasive conifer. Above- and below-ground biomass allocation and monthly measurements (April through October) of gas exchange, water relations, foliar nitrogen concentrations, and growth were made for juvenile and small-adult trees in the field in central Oregon. Compared with small adults, juveniles have greater allocations to foliage and fine-root biomass, higher rates of CO2 assimilation, leaf conductance, and transpiration, and lower investments of biomass and nitrogen per unit of foliar area. Juvenile foliage is less costly to produce than adult foliage. The suite of physiological processes associated with juvenile awl-like foliage should enhance establishment and early growth of J. occidentalis. However, high rates of water loss, which are associated with high rates of CO2 assimilation of juvenile foliage, appear to be a liability for large trees in the semiarid environment of eastern Oregon. Once established, the transition to a more conservative use of resources associated with adult scale-like foliage is consistent with the stress-tolerant strategy of long-lived evergreen trees.
Effects of the amount and composition of the forest floor on emergence and early establishment of loblolly pine seedlings
Authors: Shelton Michael G.
Published: May 2008

Five forest floor weights (0, 10, 20, 30, and 40 Mg/ha), three forest floor compositions (pine, pine–hardwood, and hardwood), and two seed placements (forest floor and soil surface) were tested in a three-factorial, split-plot design with four incomplete, randomized blocks. The experiment was conducted in a nursery setting and used wooden frames to define 0.145-m2 subplots. Forest floor composition had no significant effect on emergence or establishment of loblolly pine (Pinustaeda L.) seedlings. Numbers of emerging and established seedlings displayed a negative exponential relationship with forest floor weight (fit indices of 0.62 and 0.62, respectively). Seed placement significantly affected the number of emerging seedlings (forest floor > soil surface) and their survival (forest floor < soil surface). However, seed placement had no overall significant effect on the number of established seedlings because effects on emergence and survival essentially canceled out. Germination of herbaceous seeds in the soil bank also displayed a negative exponential trend with forest floor weight (fit indices of 0.46 and 0.50 for the weight of grasses and forbs, respectively) and was not significantly affected by forest floor composition. Results indicate that forest floor composition is not a factor in the natural regeneration of the pine component of mixed pine–hardwood stands and suggest that when pine seed production is adequate, moderate amounts of forest floor material will improve pine seedling development because of suppression of herbaceous vegetation.
Difference sampling as an alternative to importance sampling
Authors: Van Deusen Paul C.
Published: May 2008

An alternative to importance sampling is presented that is based on estimating differences between a model-based estimate and the actual quantity. Both sampling procedures are unbiased, and each is shown to have an advantage over the other in some situations. Difference sampling combines control variate methods with importance sampling and is flexible to apply.
The effect of forestry drainage practices on the emission of methane from northern peatlands
Authors: Roulet Nigel T. , Moore T. R.
Published: May 2008

Methane (CH4) flux was measured from undrained, drained, and ditched portions of treed fen, forested bog, and treed bog sites in the Wally Creek experimental drainage site (near Cochrane, Ontario), from May to October 1991. Drainage for 7 years lowered the water table from between −21 and −49 cm to −41 and −93 cm at the three respective sites. Drainage resulted in a conversion of the peatlands from a CH4 source (0 to 15 mg CH4 •m−2 •d−1) to a small CH4 sink (0 to −0.4 mg CH4 •m−2 •d−1). In contrast, CH4 efflux from the ditches ranged from <5 to >400 mg CH4 m−2 •d−1. The flux data were used to estimate the impact of forest drainage practices on net CH4 emissions from a forest drainage complex. For the treed and forested bogs, there was a net increase in CH4 emissions where ditch spacing was closer than 38 m. Even with very close ditch spacing (>12 m), there was a net decrease in CH4 flux from the treed fen. The results of this study indicate that the combination of low antecedent CH4 fluxes from an undrained peatland, and moderate fluxes from the drainage ditches, will produce a net increase in CH4 emissions from forest drainage.
Correspondence of performance between genetically related clones and seedlings
Authors: Borralho Nuno M.G. , Kanowski Peter J.
Published: May 2008

The correspondence of the performance between genetically related vegetative propagules and seedlings, as expressed by the correlation between (1) rejuvenated propagules and seedling progeny of the same parent, (2) vegetative propagules and seedlings from the same family, and (3) seedlings and vegetative propagules taken from them, was investigated. In the absence of propagation effects, expected correlations improved with increasing additive variance and the number of seedlings and propagules tested, and ranged between moderate and high. Effects due to nonadditive genetic variance varied from unimportant, in the case of seedlings and vegetative propagules of the same family, to large, in the case of seedlings and their propagules. Simulation studies demonstrated that propagation effects common to specific clones (C-effects) resulted in a significant reduction in the magnitude of correlations if the covariance with true genetic effects is negative or zero, but had little effect when the covariance is positive. Propagation effects affecting all ramets equally (c-effects) did not cause any change in the correlations. Generally, comparisons between rejuvenated propagules and seedling progeny resulted in higher correlations, and were less affected by propagation effects, than other comparisons. They were also more robust against departures from assumptions of open-pollinated family structure. Results from empirical studies seem to agree well with expectations and suggest that propagation effects might be involved on the correspondence between genetically related clones and seedlings. Implications for selection and clonal deployment strategies need further investigation.
Temperature variations in planting mounds during winter
Authors: Lindström Anders , Troeng Erik
Published: May 2008

Soil temperatures were measured at a depth of 8 cm in top, middle, and bottom positions of 30 cm high mineral and organic mounds and at 8 cm depth in scarified patches during winter and spring 1987–1988 and 1988–1989. At low air temperature, frozen mounds without snow cover showed much lower temperatures than snow-covered mounds, the maximum difference being 16 °C. During the coldest period of the two winters, when minimum air temperature was −26 °C, soil temperature in the top of a snowless mineral mound remained within −16 to −10 °C for 3.5 days and −8 to −5 °C in a snowless scarified patch. Minimum temperatures were lower, duration of low temperature freezing was longer, and temperature changes were more rapid in mineral than in organic mounds. Large temperature differences were found between the top and the bottom of mounds. In dry conditions during early spring, the upper part of the mineral mound thawed and froze repeatedly with daily maximum and minimum temperatures of 5 °C and −6 °C. Soil temperature patterns during the winter period are discussed in relation to root freezing tolerance of conifer seedlings. Mounding as a scarification method should be used with care as winter temperatures may injure seedling root systems.
Effects of nitrogen source and season of application on the nutrition and growth of iodgepole pine
Authors: Brockley R.P.
Published: May 2008

The effects of spring and fall applications of urea and ammonium nitrate fertilizer on the nutrition and growth of lodgepole pine (Pinusconforta Dougl. var. latifolia Engelm.) were evaluated at three locations in the interior of British Columbia over a 6-year period. Ammonium nitrate was generally more effective at increasing 1st-year foliar nitrogen concentration than was urea, irrespective of season of application. Spring-applied ammonium nitrate was especially effective in increasing foliar nitrogen levels. Despite the apparent superiority of ammonium nitrate over urea in improving foliar nitrogen status, the basal area increment of fertilized trees in the three trials was not affected by nitrogen source. The effect of season of application on basal area increment was not consistent across all sites or between measurement periods. Spring-applied ammonium nitrate produced the smallest 0- to 3-year basal area and height increments in two of the trials. The negative effects of fertilization on foliar sulphur concentration may partially explain the poor basal area and height response following fertilization at one site and the relatively small response to spring-applied ammonium nitrate at another site. Because spring-applied ammonium nitrate is more effective at increasing foliar nitrogen concentration, it is most likely to create a nitrogen:sulphur imbalance, at least over the short term. Further studies are warranted to test the hypothesis that ammonium nitrate is better than urea at stimulating tree growth when accompanied by sulphur additions.
Comparative analysis of algorithms to generate adjacency constraints
Authors: Yoshimoto Atsushi , Brodie J. Douglas
Published: May 2008

not available
DEFORMATION QUANTIZATION OF RELATIVISTIC PARTICLES IN ELECTROMAGNETIC FIELDS
Authors: SÁNCHEZ LAURA , GALAVIZ IMELDA , GARCÍA-COMPEÁN HUGO
Published: May 2008

The Weyl–Wigner–Moyal formalism for Dirac second-class constrained systems has been proposed recently as the deformation quantization of Dirac bracket. In this paper, after a brief review of this formalism, it is applied to the case of the relativistic free particle. Within this context, the Stratonovich–Weyl quantizer, Weyl correspondence, Moyal ⋆-product and Wigner function in the constrained phase-space are obtained. The recent Hamiltonian treatment for constrained systems, whose constraints depend explicitly on time, are used to perform the deformation quantization of the relativistic free charged particle in an arbitrary electromagnetic background. Finally, the system consisting of a charged particle interacting with a dynamical Maxwell field is quantized in this context.
REMARK ON THE CONSISTENCY OF THE LADDER APPROXIMATION AND THE RAINBOW APPROXIMATION OF DYSON–SCHWINGER EQUATIONS OF QCD
Authors: CHANG LEI , LIU YU-XIN
Published: May 2008

We study the consistency of the ladder approximation and the rainbow approximation of the Dyson–Schwinger equations of QCD. By considering the non-Abelian property of QCD, we show that the QED-type Ward–Takahashi identity is not required for the rainbow–ladder approximation of QCD. It indicates that there does not exist any internal inconsistency in the usual rainbow–ladder approximation of QCD. In addition, we propose a modified ladder approximation which guarantees the Slavnov–Taylor identity for the quark–gluon vertex omitting the ghost effect in the approximation.
PREDICTIVE MODEL OF INVERTED NEUTRINO MASS HIERARCHY AND RESONANT LEPTOGENESIS
Authors: BABU K. S. , BACHRI ABDEL G. , TAVARTKILADZE ZURAB
Published: May 2008

We present a new realization of inverted neutrino mass hierarchy based on [Formula: see text] flavor symmetry. In this scenario, the deviation of the solar oscillation angle from π/4 is correlated with the value of θ13, as they are both induced by a common mixing angle in the charged lepton sector. We find several interesting predictions: θ13≥ 0.13, sin2θ12≥ 0.31, sin2θ23≃ 0.5 and 0 ≤ cos δ ≤ 0.7 for the neutrino oscillation parameters and 0.01 ≲ mββ≲ 0.02 eV for the effective neutrino mass in neutrino-less double β-decay. We show that our scenario can also explain naturally the observed baryon asymmetry of the universe via resonant leptogenesis. The masses of the decaying right-handed neutrinos can be in the range (103–107) GeV, which would avoid the generic gravitino problem of supersymmetric models.
SPACE–TIME UNCERTAINTY RELATION AND OPERATIONAL DEFINITION OF DIMENSION
Authors: MAZIASHVILI MICHAEL
Published: May 2008

Operational definition of space–time in light of quantum mechanics and general relativity inevitably indicates an intrinsic imprecision in space–time structure which has to do with space–time dimension as well. The operational dimension of space–time turns out to be a scale dependent quantity slightly smaller than four at distances ≫lP. Close to the Planck length the deviation of space–time dimension from four becomes appreciable. The experimental bounds on the deviation of space–time dimension from four coming from the electron [Formula: see text] factor, Lamb shift in hydrogen atom and the perihelion shift in the planetary motion are still far from the theoretical predictions.
QUANTUM FIELDS ON THE GROENEWOLD–MOYAL PLANE
Authors: AKOFOR EARNEST , BALACHANDRAN A. P. , JOSEPH ANOSH
Published: May 2008

We give an introductory review of quantum physics on the noncommutative space–time called the Groenewold–Moyal plane. Basic ideas like star products, twisted statistics, second quantized fields and discrete symmetries are discussed. We also outline some of the recent developments in these fields and mention where one can search for experimental signals.
FROM BCS TO THE LHC
Authors: WEINBERG STEVEN
Published: May 2008

Reflections on spontaneous symmetry breaking, and the connection between condensed matter physics and particle physics, as given in a talk at a symposium at the University of Illinois in Urbana, celebrating the 50th anniversary of the theory of superconductivity.
LARGE VISCOUS SOLUTIONS FOR SMALL DATA IN SYSTEMS OF CONSERVATION LAWS THAT CHANGE TYPE
Authors: MATOS VÍTOR , MARCHESIN DAN
Published: May 2008

We study a quadratic system of conservation laws with an elliptic region. The second order terms in the fluxes correspond to type IV in Schaeffer and Shearer classification. There exists a special singularity for the EDOs associated to traveling waves for shocks. In our case, this singularity lies on the elliptic boundary. We prove that high amplitude Riemann solutions arise from Riemann data with arbitrarily small amplitude in the hyperbolic region near the special singularity. For such Riemann data there is no small amplitude solution. This behavior is related to the bifurcation of one of the codimension-3 nilpotent singularities of planar ODEs studied by Dumortier, Roussarie and Sotomaior.
THE GREEN'S FUNCTION FOR THE BROADWELL MODEL WITH A TRANSONIC BOUNDARY
Authors: LAN CHIU-YA , LIN HUEY-ER , YU SHIH-HSIEN
Published: May 2008

We study an initial boundary value problem for the Broadwell model with a transonic physical boundary. The Green's function for the initial boundary value problem is obtained by combining the estimates of the full boundary data and the Green's function for the initial value problem. The full boundary data is constructed from the imposed boundary data through an iteration scheme. The iteration scheme is designed to separate the interaction between the boundary wave and the interior wave and leads to a convergent series in the iterative boundary estimates.
LAX SHOCKS IN MIXED-TYPE SYSTEMS OF CONSERVATION LAWS
Authors: MAILYBAEV ALEXEI A. , MARCHESIN DAN
Published: May 2008

Small amplitude shocks involving a state with complex characteristic speeds arise in mixed-type systems of two or more conservation laws. We study such shocks in detail in the generic case, when they appear near the codimension-1 elliptic boundary. Then we classify all exceptional codimension-2 states on smooth parts of the elliptic boundary. Asymptotic formulae describing shock curves near regular and exceptional states are derived. The type of singularity at the exceptional point depends on the second and third derivatives of the flux function. The main application is understanding the structure of small amplitude Riemann solutions where one of the initial states lies in the elliptic region.
GLOBAL SOLUTIONS TO THE COMPRESSIBLE EULER EQUATIONS WITH GRAVITATIONAL SOURCE
Authors: TSUGE NAOKI
Published: May 2008

We study the compressible Euler equations in spherical symmetry with a gravitational source surrounding a solid ball. Despite its physical importance, this problem has not received much attention until now. We prove the global existence of weak solutions by constructing approximate solutions and using a modified Godunov scheme. The main point is to obtain a sup-norm bound for the approximate solutions.
ON THE UNIFORM CONTINUITY OF THE SOLUTION MAP FOR A NONLINEAR WAVE EQUATION
Authors: GEORGIEV SVETLIN GEORGIEV
Published: May 2008

We construct a metric such that the Cauchy problem for the corresponding nonlinear wave equation admits a nontrivial solution but the solution map is not uniformly continuous.
WEAK REGULAR REFLECTION FOR THE NONLINEAR WAVE SYSTEM
Authors: JEGDIĆ K.
Published: May 2008

We prove local existence of a solution to a Riemann problem for the two-dimensional nonlinear wave system using the approach by Čanić, Keyfitz, Kim and Lieberman. We consider initial data resulting in weak regular shock reflection. By writing the problem in self-similar coordinates, we obtain a mixed type system and a free boundary problem for the subsonic flow and the position of the reflected shock. We reformulate this problem using a second order equation for density with mixed boundary conditions and an ordinary differential equation describing the location of the reflected shock. The main difficulty in the study of this second order problem for density is that the operator is degenerate elliptic along the sonic circle. We regularize and modify the operator, and we show existence of solutions to the regularized problems. We prove that the sequence of solutions to the regularized problems is precompact, and, using uniform local ellipticity, covering and diagonalization techniques, we obtain a local solution to the original problem.
SBV REGULARITY OF ENTROPY SOLUTIONS FOR A CLASS OF GENUINELY NONLINEAR SCALAR BALANCE LAWS WITH NON-CONVEX FLUX FUNCTION
Authors: ROBYR ROGER
Published: May 2008

In this work we study the regularity of entropy solutions of the genuinely nonlinear scalar balance laws [Formula: see text] We assume that the source term g ∈ C1(ℝ × ℝ × ℝ+), that the flux function f ∈ C2(ℝ × ℝ × ℝ+) and that {ui∈ ℝ : fuu(ui,x,t) = 0} is at most countable for every fixed (x,t) ∈ Ω. Our main result, which is a unification of two proposed intermediate theorems, states that BV entropy solutions of such equations belong to SBVloc (Ω). Moreover, using the theory of generalized characteristics we prove that for entropy solutions of balance laws with convex flux function, there exists a constant C > 0 such that: [Formula: see text] where C can be chosen uniformly for (x + h,t), (x,t) in any compact subset of Ω.
POINTWISE ESTIMATES FOR THE WAVE EQUATION WITH DISSIPATION IN ODD SPATIAL DIMENSION
Authors: XU HONGMEI , WANG WEIKE
Published: May 2008

We study the pointwise estimate of solution to the Cauchy problem for the wave equation with viscosity in odd spatial dimension. Through the explicit analysis of the Green function, we obtain the large time behavior of solution, and the solution exhibit the generalized Huygens principle.
Weak Gravitational Lensing and Its Cosmological Applications
Authors: Hoekstra Henk , Jain Bhuvnesh
Published: May 2008

Weak gravitational lensing is a unique probe of the dark side of the universe: It provides a direct way to map the distribution of dark matter around galaxies and clusters of galaxies as well as on cosmological scales. Furthermore, the measurement of the weak lensing–induced distortions of the shapes of distant galaxies is a potentially powerful probe of dark energy. In this review we discuss how this challenging measurement is made and interpreted. We describe the various systematic effects that can hamper progress and how they may be overcome. We review some of the recent results in weak lensing by galaxies, galaxy clusters, and cosmic shear and discuss the prospects for dark energy measurements from planned surveys.
Cystic Fibrosis and Nutrition: Linking Phospholipids and Essential Fatty Acids with Thiol Metabolism
Authors: Innis Sheila M. , Davidson A. George F.
Published: May 2008

Cystic fibrosis (CF) is the most common lethal inherited disorder among Caucasians and results from mutation in the gene encoding the CF transmembrane conductance regulator. In addition to its multisystem clinical effects, the disease is characterized by increased proinflammatory mediators and oxidant stress, and systemic redox imbalance with reduced glutathione (GSH), together with alterations in circulating and tissue (n-6) and (n-3) fatty acids, particularly a decrease in docosahexaenoic acid. The metabolism of phospholipids and fatty acids is closely related to GSH through the methionine-homocysteine cycle, in which choline via betaine provides methyl groups to regenerate S-adenosylmethionine, important in generating phosphatidylcholine and amino acid precursors for GSH. Current research focuses both on fatty acid supplementations to normalize altered (n-6) to (n-3) fatty acid balance and decrease generation of (n-6) fatty acid-derived inflammatory mediators, and strategies to improve oxidant defenses and redox balance. However, further research is needed before such strategies can be included in clinical care of individuals with CF.
Poloxamer 188 reduces the contraction-induced force decline in lumbrical muscles from mdx mice
Authors: Ng Rainer , Metzger Joseph M. , Claflin Dennis R. , Faulkner John A.
Published: May 2008

Duchenne Muscular Dystrophy is a genetic disease caused by the lack of the protein dystrophin. Dystrophic muscles are highly susceptible to contraction-induced injury, and following contractile activity, have disrupted plasma membranes that allow leakage of calcium ions into muscle fibers. Because of the direct relationship between increased intracellular calcium concentration and muscle dysfunction, therapeutic outcomes may be achieved through the identification and restriction of calcium influx pathways. Our purpose was to determine the contribution of sarcolemmal lesions to the force deficits caused by contraction-induced injury in dystrophic skeletal muscles. Using isolated lumbrical muscles from dystrophic ( mdx) mice, we demonstrate for the first time that poloxamer 188 (P188), a membrane-sealing poloxamer, is effective in reducing the force deficit in a whole mdx skeletal muscle. A reduction in force deficit was also observed in mdx muscles that were exposed to a calcium-free environment. These results, coupled with previous observations of calcium entry into mdx muscle fibers during a similar contraction protocol, support the interpretation that extracellular calcium enters through sarcolemmal lesions and contributes to the force deficit observed in mdx muscles. The results provide a basis for potential therapeutic strategies directed at membrane stabilization of dystrophin-deficient skeletal muscle fibers.
Inhibition of transient receptor potential A1 channel by phosphatidylinositol-4,5-bisphosphate
Authors: Kim Donghee , Cavanaugh Eric J. , Simkin Dina
Published: May 2008

Membrane phosphatidylinositol-4,5-bisphosphate (PIP2) is critical for the function of many transient receptor potential (TRP) ion channels. The role of PIP2 in TRPA1 function is not well known. The effect of PIP2 on TRPA1 was investigated by direct application of PIP2 and by using polylysine and PIP2 antibody that sequester PIP2. In inside-out patches from HeLa cells expressing mouse TRPA1, polytriphosphate (PPPi) was added to the bath solution to keep TRPA1 sensitive to allyl isothiocyanate (AITC; mustard oil). Direct application of PIP2 (10 μM) to inside-out patches did not activate TRPA1, but AITC and Δ9-tetrahydrocannabinol (THC) produced strong activation. In inside-out patches in which TRPA1 was first activated with AITC (in the presence of PPPi), further addition of PIP2 produced a concentration-dependent inhibition of TRPA1 [agonist concentration producing half-maximal activity ( K1/2), 2.8 μM]. Consistent with the inhibition of TRPA1 by PIP2, AITC activated a large whole cell current when polylysine or PIP2 antibody was added to the pipette but a markedly diminished current when PIP2 was added to the pipette. In inside-out patches with PPPi in the bath solution, application of PIP2 antibody or polylysine caused activation of TRPA1, and this was blocked by PIP2. However, TRPA1 was not activated by polylysine and PIP2 antibody under whole cell conditions, suggesting a more complex regulation of TRPA1 by PIP2 in intact cells. These results show that PIP2 inhibits TRPA1 and reduces the sensitivity of TRPA1 to AITC.