bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a Three-Dimensional Molten Carbonate Fuel Cell Model and Application to Hybrid Cycle Simulations
Authors: Iora P. , Campanari S.
Published: November 2007

In this paper, a three-dimensional finite volume model of a molten carbonate fuel cell (MCFC) is presented. The model applies a detailed electrochemical and thermal analysis to a planar MCFC stack of given geometry and assigned input flows conditions, material properties and assigned external heat losses, calculating global energy balances and reactant utilization, as well as internal temperature and chemical composition profiles, pressure profiles, polarization losses, and current density and voltage distribution over the stack. The model is calibrated on the available data for an experimented MCFC stack manufactured by Ansaldo Fuel Cells. The comparison of 2D versus 3D simulations is first discussed, showing the importance of the 3D model for an accurate analysis of real stack operation under significant heat loss conditions, but also showing the mutual influence of heat transfer between adjoining cells and evidencing the variable electrical performances between different cells of the same stack. As a counterpart, application of the 2D model, which takes advantage by much shorter calculation time while keeping a reasonable accuracy in the overall energy balances, is anyway indicated for complex cycle analysis and cycle optimization, where a complete 3D stack analysis may be limited to selected cases. Then, the model is applied to the off-design analysis of hybrid cycles based on a recuperated gas turbine arrangement where variable pressure ratios and fuel supply conditions are assumed for the fuel cell. The effects of the operating pressure and of the adoption of different fuel compositions are considered, with a cycle layout that may include natural gas reforming or is directly fed by a syngas provided by an external source, simulating different fuel feedstocks (e.g., coal gasification). Complete results are presented, in terms of fuel cell and overall cycle performances.
Heat
Transfer and Fluid Flow Characteristics of Separated Flows Encountered in a Backward-Facing Step
Under the Effect of Suction and Blowing
Authors: Abu-Nada E. , Al-Sarkhi A. , Akash B. , Al-Hinti I.
Published: November 2007

Numerical investigation of heat transfer and fluid flow over a backward-facing step (BFS), under the effect of suction and blowing, is presented. Here, suction/blowing is implemented on the bottom wall (adjacent to the step). The finite volume technique is used. The distribution of the modified coefficient of friction and Nusselt number at the top and bottom walls of the BFS are obtained. On the bottom wall, and inside the primary recirculation bubble, suction increases the modified coefficient of friction and blowing reduces it. However, after the point of reattachment, mass augmentation causes an increase in the modified coefficient of friction and mass reduction causes a decrease in modified coefficient of friction. On the top wall, suction decreases the modified coefficient of friction and blowing increases it. Local Nusselt number on the bottom wall is increased by suction and is decreased by blowing, and the contrary occurs on the top wall. The maximum local Nusselt number on the bottom wall coincides with the point of reattachment. High values of average Nusselt number on the bottom wall are identified at high Reynolds numbers and high suction bleed rates. However, the low values correspond to high blowing rates. The reattachment length and the length of the top secondary recirculation bubble are computed under the effect of suction and blowing. The reattachment length is increased by increasing blowing bleed rate and is decreased by increasing suction bleed rate. The spots of high Nusselt number, and low coefficient of friction, are identified by using contour maps.
How to teach friction: Experiments and models
Authors: Besson Ugo , Borghi Lidia , De Ambrosis Anna , Mascheretti Paolo
Published: November 2007

Students generally have difficulty understanding friction and its associated phenomena. High school and introductory college-level physics courses usually do not give the topic the attention it deserves. We have designed a sequence for teaching about friction between solids based on a didactic reconstruction of the relevant physics, as well as research findings about student conceptions. The sequence begins with demonstrations that illustrate different types of friction. Experiments are subsequently performed to motivate students to obtain quantitative relations in the form of phenomenological laws. To help students understand the mechanisms producing friction, models illustrating the processes taking place on the surface of bodies in contact are proposed.
Two examples of circular motion for introductory courses in relativity
Authors: Wortel Stephanie , Malin Shimon , Semon Mark D.
Published: November 2007

The circular twin paradox and Thomas precession are presented in a way that makes them accessible to students in introductory relativity courses. Both are discussed by examining what happens during travel around a polygon and then in the limit as the polygon becomes a circle. Because relativistic predictions based on these examples are verified in experiments with macroscopic objects (such as atomic clocks flown in airplanes and the gyroscopes on Gravity Probe B), they are especially convincing to introductory students.
The role of the density operator in the statistical description of quantum systems
Authors: Sabbaghzadeh Jamshid , Dalafi Ali
Published: November 2007

A quantum mechanical system that is described by a state vector can be equally described by a density operator, although the inverse is not true. When information about a system is incomplete the only way to describe the system is by the density operator formalism. Incompleteness arises in two general cases: a mixed ensemble of physical systems and a system that interacts with its environment. We shed light on some subtle points that are usually misunderstood. We show explicitly that in the first case the averaged state vector of the system is zero, and in the second case no state vector can be assigned to the system in general.
Antiplasmodial Activity of [(Aryl)arylsulfanylmethyl]Pyridine
Authors: Kumar Sanjay , Das Sajal Kumar , Dey Sumanta , Maity Pallab , Guha Mithu , Choubey Vinay , Panda Gautam , Bandyopadhyay Uday
Published: November 2007

A series of [(aryl)arylsufanylmethyl]pyridines (AASMP) have been synthesized. These compounds inhibited hemozoin formation, formed complexes (

K
D

= 12 to 20 μM) with free heme (ferriprotoporphyrin IX) at a pH close to the pH of the parasite food vacuole, and exhibited antimalarial activity in vitro. The inhibition of hemozoin formation may develop oxidative stress in
Plasmodium falciparum
due to the accumulation of free heme. Interestingly, AASMP developed oxidative stress in the parasite, as evident from the decreased level of glutathione and increased formation of lipid peroxide, H
2
O
2
, and hydroxyl radical (·OH) in
P. falciparum
. AASMP also caused mitochondrial dysfunction by decreasing mitochondrial potential (ΔΨm) in malaria parasite, as measured by both flow cytometry and fluorescence microscopy. Furthermore, the generation of ·OH may be mainly responsible for the antimalarial effect of AASMP since ·OH scavengers such as mannitol, as well as spin trap α-phenyl-
n
-tertbutylnitrone, significantly protected
P. falciparum
from AASMP-mediated growth inhibition. Cytotoxicity testing of the active compounds showed selective activity against malaria parasite with selectivity indices greater than 100. AASMP also exhibited profound antimalarial activity in vivo against chloroquine resistant
P. yoelii
. Thus, AASMP represents a novel class of antimalarial.
Decline in Sulfadoxine-Pyrimethamine-Resistant Alleles after Change in Drug Policy in the Amazon Region of Peru
Authors: Zhou Zhiyong , Griffing Sean M. , de Oliveira Alexandre Macedo , McCollum Andrea M. , Quezada Wilmer Marquino , Arrospide Nancy , Escalante Ananias A. , Udhayakumar Venkatachalam
Published: November 2007

The frequency of alleles with triple mutations conferring sulfadoxine-pyrimethamine (SP) resistance in the Peruvian Amazon Basin has declined (16.9% for
dhfr
and 0% for
dhps
compared to 47% for both alleles in 1997) 5 years after SP was replaced as the first-line treatment for
Plasmodium falciparum
malaria. Microsatellite analysis showed that the
dhfr
and
dhps
alleles are of common origin.
Usefulness of Alternate Prognostic Serum and Plasma Markers for Antiretroviral Therapy for Human Immunodeficiency Virus Type 1 Infection
Authors: Kannangai R. , Kandathil A. J. , Ebenezer D. L. , Mathai E. , Prakash A. J. , Abraham O. C. , Sudarsanam T. D. , Pulimood S. A. , Selvakumar R. , Job V. , Sridharan G.
Published: November 2007

In developing countries, the usability of peripheral blood constituents that are low-cost alternatives to CD4-positive (CD4+) T-cell and human immunodeficiency virus type 1 (HIV-1) RNA estimation should be evaluated as prognostic markers. The aim of our study was to investigate the use of plasma levels of dehydroepiandrosterone sulfate (DHEAS), albumin, and C-reactive protein (CRP) as alternate prognostic markers for antiretroviral treatment (ART) response in place of HIV-1 load measurements. Paired blood samples were collected from 30 HIV-infected individuals before and after initiation of ART, 13 HIV-infected individuals before and after completion of antituberculosis therapy (ATT), and 10 HIV-infected individuals not on either ATT or ART. Because of the nonavailability of samples, the CRP estimation was done for samples from only 19, 9, and 8 individuals in groups 1, 2, and 3, respectively. The measurements of all three markers, i.e., DHEAS, albumin, and CRP, were carried out with commercial assays. The differences in the albumin levels before and after ART or ATT were significant (P< 0.05), while the differences in DHEAS and CRP levels were not significant (P> 0.05). When levels of DHEAS among the individuals who were followed up were analyzed, 13 (44.8%) in the ART group and 9 (69%) in the ATT group showed an increase following treatment. Prior to treatment of HIV-infected individuals, there was a significant positive correlation of CD4+T-cell counts and a negative correlation of viral load with albumin and DHEAS levels (P< 0.01). Among the three plasma markers we tested, plasma albumin and, to some extent, DHEAS show promise as prognostic markers in monitoring HIV infection.
Simultaneous Detection of Eight Analytes in Human Serum by Two Commercially Available Platforms for Multiplex Cytokine Analysis
Authors: Toedter Gary , Hayden Karen , Wagner Carrie , Brodmerkel Carrie
Published: November 2007

The accurate detection and quantitation of cytokines in serum are important in the study of disease mechanisms, pathogenesis, and treatment. Serum cytokines can reflect processes that are occurring at the cellular or tissue level and thus provide a means of indirectly monitoring these processes. Multiplex detection of cytokines allows the simultaneous measurement of multiple cytokines in a sample, increasing the efficiency of measuring the cytokines while reducing the serum sample volumes required for the testing. Two commercially available multiplex platforms were evaluated (Pierce SearchLight and Meso Scale Discovery), using multiplexes capable of simultaneously detecting eight cytokines. The cytokines analyzed in this study were gamma interferon, vascular endothelial growth factor, tumor necrosis factor alpha, interleukin-6 (IL-6), macrophage inflammatory protein 1β, monocyte chemoattractant protein 1, IL-12p40, and IL-4. The range of quantitation of the platforms, the recovery of spiked cytokines, and the detection of the cytokines in serum samples from subjects with ulcerative colitis, Crohn's disease, rheumatoid arthritis, and psoriasis were examined. The findings showed that the detection of the cytokines was highly dependent upon the platform, with the consistency of the detection of cytokines across platforms being dependent upon the cytokine being analyzed. A careful examination of platform assay performance must be made prior to utilizing multiplex platforms in a study. While some cytokines will give similar patterns of results across platforms, others will be highly variable. The use of the same platform within a study or across studies where data will be compared is advised.
Quantitative Measurement of C
6
Antibody following Antibiotic Treatment of
Borrelia burgdorferi
Antibody-Positive Nonclinical Dogs
Authors: Levy Steven A. , O'Connor Thomas P. , Hanscom Jancy L. , Shields Paulette , Lorentzen Leif , DiMarco Anthony A.
Published: November 2007

The detection of antibody to the
Borrelia burgdorferi
C
6
peptide by use of enzyme-linked immunoassays is a widely accepted method for the diagnosis of Lyme disease spirochete infection in dogs and in humans. Antibody to the C
6
peptide is highly specific for
B. burgdorferi
and declines following treatment of dogs and humans exposed to
B. burgdorferi
. A quantitative assay for determining C
6
antibody levels was developed and used to measure changes in antibody levels following antibiotic treatment of
B. burgdorferi
antibody-positive nonclinical dogs. One hundred thirty-two client-owned dogs were used in the study; 64 were negative, 53 of 68 positive animals received treatment, and 15 were untreated controls. Test sera were collected at 3, 6, and 12 months from seropositive dogs receiving treatment and untreated controls. Dogs in the treated group were assigned to moderate-to-high (≥29 U/ml)- and low (<29 U/ml)-C
6
-level groups because the change in the C
6
level after treatment was dependent on the level prior to treatment. There were significant declines in the 30 dogs with moderate-to-high initial C
6
levels that exceeded the maximal declines of the untreated control dogs in all cases at 6 months (16 data points) and 12 months (29 data points) posttreatment. There was little change in C
6
level following antibiotic therapy in the 23 dogs with low initial C
6
levels. The quantitative C
6
antibody test can be used to measure changes in C
6
antibody levels following treatment of antibody-positive nonclinical dogs.
Gingipains fromPorphyromonas gingivalisIncrease the Chemotactic and Respiratory Burst-Priming Properties of the 77-Amino-Acid Interleukin-8 Variant
Authors: Dias Irundika H. K. , Marshall Lindsay , Lambert Peter A. , Chapple Iain L. C. , Matthews John B. , Griffiths Helen R.
Published: November 2007

Porphyromonas gingivalis, a gram-negative anaerobe which is implicated in the etiology of active periodontitis, secretes degradative enzymes (gingipains) and sheds proinflammatory mediators (e.g., lipopolysaccharides [LPS]). LPS triggers the secretion of interleukin-8 (IL-8) from immune (72-amino-acid [aa] variant [IL-872aa]) and nonimmune (IL-877aa) cells. IL-877aahas low chemotactic and respiratory burst-inducing activity but is susceptible to cleavage by gingipains. This study shows that both R- and K-gingipain treatments of IL-877aasignificantly enhance burst activation by fMLP and chemotactic activity (P< 0.05) but decrease burst activation and chemotactic activity of IL-872aatoward neutrophil-like HL60 cells and primary neutrophils (P< 0.05). Using tandem mass spectrometry, we have demonstrated that R-gingipain cleaves 5- and 11-aa peptides from the N-terminal portion of IL-877aaand the resultant peptides are biologically active, while K-gingipain removes an 8-aa N-terminal peptide yielding a 69-aa isoform of IL-8 that shows enhanced biological activity. During periodontitis, secreted gingipains may differentially affect neutrophil chemotaxis and activation in response to IL-8 according to the cellular source of the chemokine.
Sequential Outbreaks of Infections by Distinct
Acinetobacter baumannii
Strains in a Public Teaching Hospital in Houston, Texas
Authors: Shelburne Samuel A. , Singh Kavindra V. , White A. Clinton , Byrne Laura , Carmer Alexis , Austin Celest , Graviss Edward , Stager Charles , Murray Barbara E. , Atmar Robert L.
Published: November 2007

Invasive disease due to
Acinetobacter baumannii
is an increasing problem in health care settings worldwide. Whether certain clones of
A. baumannii
are more likely to cause invasive disease in hospitalized patients is unknown. We studied all patients at a public teaching hospital in Houston, Texas, from whom the
Acinetobacter calcoaceticus-Acinetobacter baumannii
complex was isolated over a 14-month period in 2005 to 2006. One hundred seven unique patient isolates were identified, with 87 of the strains classified as being
A. baumannii
, the majority of which were multidrug resistant. The
A. baumannii
isolates were comprised of 18 unique pulsed-field types, with strains of clone A and clone B accounting for 66 of the 87 isolates. Epidemiologic analysis showed the predominance of the two
A. baumannii
clones at distinct time periods, with the remainder of the
A. baumannii
and non-
A. baumannii
strains being evenly distributed. Patients from whom clone A strains were isolated were more likely to be bacteremic than were patients with other
A. baumannii
isolates. Conversely, clone B strains were more likely to be isolated from patients with tertiary peritonitis. Patients from whom clone A was isolated had a significantly higher rate of mortality. Multilocus sequence typing demonstrated that clones A and B are related to each other and to
A. baumannii
strains previously isolated in Western Europe, sharing five of seven alleles. Taken together, we conclude that the outbreak of the
A. calcoaceticus-A. baumannii
complex in our institution was due to two distinct
A. baumannii
clones that were associated with significantly different patient outcomes.
Fungal Infection in Patients with Serpiginous Choroiditis or Acute Zonal Occult Outer Retinopathy
Authors: Pisa Diana , Ramos Marta , García Patricia , Escoto Remberto , Barraquer Rafael , Molina Susana , Carrasco Luis
Published: November 2007

The etiologies of a number of retinopathies, including serpiginous choroiditis and acute zonal occult outer retinopathy (AZOOR), remain uncertain. Recently, we provided evidence that AZOOR is caused byCandida famatainfection. The purpose of this article was to investigate the presence of fungal infection in five patients affected with serpiginous choroiditis and five patients with diagnosis of AZOOR. To assess the presence of fungal infection the presence of antibodies in human serum samples againstC. famata,C. albicans,C. parapsilosis,C. glabrataandC. kruseiwas analyzed. In addition, quantitative PCR was carried out to detect fungal genomes in whole blood. Finally, the presence of fungal antigens in the serum samples of patients was investigated. Three AZOOR patients presented high antibody titers againstCandidaspp., while antibodies againstCandidaspp. were observed in serum samples from four patients with serpiginous choroiditis. Fungal genomes in peripheral blood were evidenced in serum samples from one AZOOR and four serpiginous choroiditis patients. Fungal antigens were also apparent in the serum of different patients. Our findings indicate that there was evidence of disseminated fungal infection in most patients examined.
Curry Draw, Cochise County, Arizona
Authors: Haynes C. Vance
Published: November 2007

Curry Draw, a typical discontinuous gully, is an easterly flowing tributaryof the upper San Pedro River in Cochise County, Arizona (Fig. 1). The arroyo, which appears as an unnamed drainage on the Lewis Springs 7½-minute Quadrangle, exposes the Murray Springs Clovis site in the SW¼SE¼-Sec.26, T21S, R21E, (31°34'13''N, 110°10'40'' W). The site where the stratigraphy is best exposed is reached on foot by following the draw downstream 0.65 mi (1.1 km) from where it crosses Meson Road or by following the abandoned Southern Pacific railroad grade that parallels the draw on the north side. The site is on property of the Bureau of Land Management, and permission to visit it must be obtained from the Safford District Office, 425 East 45th Street, Safford, Arizona 85546.
The Merced Formation and related beds
Authors: Clifton H. Edward , Hunter Ralph E.
Published: November 2007

The Merced Formation and consanguineous superjacent strata are well exposed in seacliffs that extend 4.3 mi (7 km) south from Lake Merced to the trace of the San Andreas fault (Fig. 1). The exposures can be reached by walking south along the beach from oceanfront public parking areas west of Lake Merced or via several well-defined trails that lead to the beach from Fort Funston (Fig. 1), a part of the Golden Gate Recreational Area, which provides public parking. The southern part of the exposure can be reached by walking north from a public parking area at Mussel Rock (Fig.1), which can be reached via an access road from Westline Drive in northern Pacifica (Edgemar). The central part of the exposure is presently accessible via a road to the former Thornton Beach State Park at the western end of Alemany Boulevard. This road, however, is now badly disrupted by landslides and affords uncertain future accessibility.

The character of the exposure changes as a consequence of local landsliding and seasonal variation in the level of beach sand. The deposits are best viewed following winter storms when the erosion of beach sand provides for fresh, wave-washed exposure. The observer of these deposits should continually be alert forrock falls and the possibility of being isolated by arising tide.
Teton mountain front, Wyoming
Authors: Love J. D.
Published: November 2007

Three vantage points from which to view the Teton mountain front are discussed (Figs. 1, 2) all in Grand Teton National Park, Teton County, Wyoming. Site 1 is in the NW¼NW¼ Sec.26,T.44N.,R.115W. (U.S.G.S. 7½-minute topographic map of Moran Quadrangle, 1968). Site 2 is in the NW¼SW¼SW¼ Sec.1,T.43N.,R.116W. (U.S.G.S. 7¼-minute topographic map of Moose Quadrangle, 1968). Site 3 is in the center SE¼ Sec.12,T.44N.,R.116W. (U.S.G.S. 7¼-minute topographic map of the Jenny Lake Quadrangle, 1968).
The Calvin 28 cryptoexplosive disturbance, Cass County, Michigan
Authors: Milstein Randall L.
Published: November 2007

Geophysical data, geologic mapping, and the extensive drilling of oil and gas test wells have delineated a subsurface structure in Calvin Township, Cass County, Michigan, T.7S., R.14W.; Adamsville, Michigan, 7½-minute Quadrangle, The center of the structure is approximately 1 mi (1.4 km) southwest of the village of Calvin Center (Fig.1), 1). The feature maintainsa surface topographic expression and a partially encircling drainage pattern, but its major structural complexity is concealed by drift and Paleozoic rock.

The location of the Calvin 28 cryptoexplosive disturbanceis shown in Figure 1, which uses an idealized geologic map as a base and to which road numbers have been added. The Calvin 28 cryptoexplosive disturbance can be reached by driving 4 mi (6.4 km) east on Michigan 60 from Cassopolis until encountering the intersection of Calvin Center Road. A right (south) turn on Calvin Center Road will take the visitor toward the structure. After traveling 4.2 mi (6.8 km) on Calvin Center Road, thevisitor will cross over the outer encircling rim of the structure. The outer edge of this rim is delineated by a chain of lakes connected by Christiana Creek (Fig.1), 2). Continuing south on Calvin Center Road 0.5 mi (0.8 km), one encounters the village of Calvin Center. The village is located, subtly, within the annular depression surrounding the central uplift of the structure. Continue south an additional 1 mi (1.6 km) to the junction of Calvin Hill Stree and turn right (west). By traveling 0.5
Field dispersal of Pseudomonas syringae pv. tomato, Xanthomonas campestris pv. vesicatoria, and Alternaria macrospora by animals, people, birds, insects, mites, agricultural tools, aircraft, soil particles, and water sources
Authors: Bashan Yoav
Published: November 2007

Viable disseminating units of Pseudomonas syringae pv. tomato (Okabe) Young, Dye and Wilkie and Xanthomonas campestris pv. vesicatoria (Doidge) Dye, the bacterial leaf pathogens of tomato and pepper, respectively, and Alternaria macrospora Zimm, the causal agent of Alternaria blight in cotton, were found to be carried by a wide variety of agents including animals, people, insects, mites, agricultural tools, aircraft, soil particles, and water sources. Of these, specific insects and tools commonly used for crop cultivation were the most heavily contaminated. Soil adhering to agricultural tools or carried by various water sources can also serve as a disseminating agent. It was concluded that nearly all accidental agents passing through the infested field may act as vectors of these pathogens.
An investigation of product form
Authors: Roebbelen P. , Smith V. G.
Published: November 2007

Product form (P) of a tree has been defined as the product of diameter-outside-bark at midheight above breast height (d) and total height (H) (P = d × H). It is used along with diameter breast height (D) in product form volume equations (VPF = f(P,D)) for estimating individual tree volumes. It is hypothesized that for each coniferous species, there exists some optimal height at which a diameter measurement can be taken and used in a product form term to estimate the inside-bark volume with minimum error. Regression equations and simpler expressions of the form V = D2 × H × F were developed for red pine (Pinusresinosa Ait.), white pine (Pinusstrobus L.), jack pine (Pinusbanksiana Lamb.), and black spruce (Piceamariana (Mill.) B.S.P.) using six upper diameter locations. The optimal location of the upper diameter was found to be 50% of the total height for red pine and white pine and 47% of total height for jack pine and black spruce. Product form is redefined as P = d* × H where d* = diameter-outside-bark at that average relative height on the tree where d* = (2 × V)/(D × H) as determined from a small sample of scaled trees, for each species and H = total height of tree.
Relaxing even-flow constraints to avoid infeasibility with the Timber Resources Allocation Method (RAM)
Authors: Armstrong Glen W. , Beck Jr. James A. , Phillips Barrie L.
Published: November 2007

When inflexible rotation ages for regenerated timber are coupled with a strictly interpreted policy of nondeclining or even flow of timber volume, a mathematically feasible harvest schedule often does not exist. This problem of infeasibility can be avoided by relaxing the definition of even or nondeclining flow used in the postconversion period of the Timber Resources Allocation Method (RAM). Relaxed flow policies can lead to scheduled harvest volumes which fluctuate greatly from decade to decade in the postconversion period. Explicitly planning for these fluctuations seems to violate the principle of sustained yield and some believe it may lead to a poorly regulated forest. However, when frequent review and reassessment of harvest schedules for two Alberta forest management units were simulated, undesirable fluctuations in future harvest volumes did not occur and the resulting forest structures were reasonably regular.
Effect of urea fertilization on allometric relations in young Douglas-fir trees
Authors: Grier Charles C. , Lee Katharine M. , Archibald Ruth M.
Published: November 2007

The effect of nitrogen fertilization on allometric relations was examined for 23-year-old site class III Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) trees 2 years after urea fertilization. Logarithmic regression equations using stem diameter (centimetres) to predict tree biomass components (kilograms) were not significantly (p = 0.05) different between fertilized and control trees for total foliage, total branch, dead branch, stembark, or stemwood. New foliage and new twig components, however, were higher in fertilized trees than in control trees. Analysis of data from this and earlier studies suggests fertilization will increase leaf biomass per tree relative to control trees on sites having low nitrogen availability; however, this response will decrease with increasing nitrogen availability. Regression equations based on regional analysis of unfertilized trees yield estimates of foliage biomass for average trees on average sites. If N fertilization brings the site above average in terms of nitrogen availability then these regression equations will underestimate foliage biomass. However, on sites that are initially very nitrogen deficient, N fertilization will bring the site closer to average in terms of nitrogen availability, resulting in more accurate predictions of foliage biomass for fertilized stands than for control stands.
Population studies of white spruce. II. Natural inbreeding and relatedness among neighboring trees
Authors: Park Y. S. , Fowler D. P. , Coles J. F.
Published: November 2007

Natural inbreeding and relatedness among neighboring trees were studied in several central New Brunswick populations of white spruce (Piceaglauca (Moench) Voss). Coefficients of relationship (r) were estimated by comparing the self-, neighbor-, open-, and unrelated-pollination effects on percent full seed. The estimates were 0.29 and 0.28 for neighbor and open pollinations, respectively. The effects of natural inbreeding on juvenile traits, e.g., germination and early growth, were slight while the effect on height growth increased with age at least to age 7 years. Neighboring white spruce trees growing in natural stands appear to be related at about the half-sib level (r = 0.25). Based on percent full seed, open-pollination approximates a level of inbreeding expected from trees related at a level well above that of half-sibs. Differential selection at the pre-embryo to early seedling stages results in progenies again related at the half-sib level. It is suggested that an inbreeding equilibrium exists in natural stands of white spruce and that this equilibrium approximates that expected from half-sib matings (F = 0.125). The inbreeding equilibrium is controlled, at least in part, by the frequency of lethal genes in the populations.
Effects of clear-cutting on the vegetation and soil of an eastern hemlock dominated ecosystem, western Upper Michigan
Authors: Hix David M. , Barnes Burton V.
Published: November 2007

The effects of clear-cutting on the vegetation and soil of an ecosystem dominated by eastern hemlock (Tsugacanadensis (L.) Carr.) were studied at four locations along the boundaries of the Sylvania Recreation Area (Ottawa National Forest) in western Upper Michigan, U.S.A. The position of commercially clear-cut areas along the boundaries of the relatively undisturbed 8500-ha tract provided the opportunity to examine the probable effects of clear-cutting after an average of 46 years afterward. Clear-cutting resulted in the virtual elimination of hemlock from the overstory; it was replaced by a mixed forest of red maple (Acerrubrum L.), yellow birch (Betulaalleghaniensis Britt.), sugar maple (Acersaccharum Marsh.), and balsam fir (Abiesbalsamea L.). The ecological species groups characteristic of the ground cover of the uncut plots were not substantially different from the groups now present on the clear-cut plots. The thickness, mass, and nutrient (K+, Mg2+, Ca2+) contents of the forest floor decreased significantly, and the acidity and nutrient contents of the upper mineral soil increased slightly. The replacement of hemlock by hardwoods has slowly decreased the acidity and apparently increased the rate of nutrient cycling. It appears that without major disturbance, such as fire, hemlock is not likely to regain dominance following clear-cutting owing to failure to regenerate naturally.
Low temperature germination of Fraser fir seed
Authors: Blazich Frank A. , Hinesley L. Eric
Published: November 2007

Fraser fir (Abiesfraseri (Pursh) Poir.) seed germinated under moist conditions at 5 °C. Daily illumination in combination with an initial benomyl treatment resulted in earlier commencement of germination (16 weeks) compared with nontreated seeds maintained in darkness (23 weeks). Germination was greatly enhanced by exposing seeds four times daily to 15 min. illumination from cool-white fluorescent lights.
Juvenile height growth of aspen species and hybrids in southeastern Michigan
Authors: Brissette John C. , Barnes Burton V.
Published: November 2007

The possibility that in southeastern Michigan Populusgrandidentata and P. tremuloides may eventually form a hybrid swarm through their hybrid (P. × smithii) and backcrosses was studied. The competitive relationships among the taxa was examined by comparing their juvenile growth. The F1 hybrid and backcrosses to either parent grew in height nearly as well as P. tremuloides through their 2nd year from seed. Populusgrandidentata was outgrown by the hybrids and backcrosses for the 1st year but grew to approximately the same total height by the end of the second season. Seedlings of hybrids and backcrosses exhibit neither hybrid vigor nor marked growth inferiority compared with those of the parents. Growth rate is not a limiting factor to gene flow among the parent species.
Winter damage to foliage as a factor in red spruce decline
Authors: Friedland Andrew J. , Gregory Robert A. , Karenlampi Lauri , Johnson Arthur H.
Published: November 2007

Observations made over the past 5 years suggest that the most recent needles of red spruce (Picearubens Sarg.) in the Green Mountains of Vermont, U.S.A., are prone to browning and loss owing to cold stress and (or) winter desiccation. Particularly severe events occurred in the winters of 1981 and 1984 and the latter event was observed in detail. On many trees in all size classes, a large proportion of the 1983 needles turned reddish-brown between late February and early April, 1984. This pattern of discoloration and subsequent defoliation, which appears to be repeated periodically, can account for the visual symptoms of declining red spruce in the montane forests of the northeastern United States. A predisposition to winter damage appears to be a component of the decline and could result from natural or possibly anthropogenic factors.
The effects of supraoptimal temperatures upon North American brown-rot fungi in pure culture
Authors: Palmer John G. , Payne Ruth G.
Published: November 2007

Ninety-one North American brown-rot fungi were exposed in agar culture to four high temperatures for 16 days. Isolates originated from basidiospores, sporophore tissue, or decaying wood. One or more isolates of 58 species grew at 35 °C, of 20 species at 41 °C, and of 4 species at 46 °C; none grew at 52 °C. Similar inter- and intra-specific variations occurred during recoveries in the absence of growth. Some isolates of two species of Antrodia recovered after exposure to 52 °C. The possibility that a brown rotter might be active, alive but inactive, or neither within a wood substrate can be inferred by comparison of ratings derived by mathematical formulae applied to species represented by four or more isolates. Species that destroy wood products made up 73% of those likely to grow at these higher temperatures and 81% of those most likely to recover from exposure to supramaximal temperatures based upon these ratings. Only 2 of the 12 fungi least capable of growth and recovery at high temperatures were associated with forest products. Temperature ratings for two fungi that had been isolated by another worker from western pine slash coincided with the upper and lower portions in which they occurred. However, field data were insufficient for a satisfactory comparison of sapwood and heartwood rotters.
Competition-induced changes in developmental features of planted Douglas-fir in southwestern British Columbia
Authors: Brand David G.
Published: November 2007

One- to five-year-old Douglas-fir, planted operationally, were measured for various developmental characteristics indicative of competition-induced acclimation to resource limitations. Characteristics were tested against a competition index based on measures of the brush canopy surrounding individual trees. The most promising developmental characteristics for assessing competition stress were the specific leaf area of foliage, the allometric relationship of height to basal area, and bud production on nodal shoots. Measures of foliar nitrogen status and leaf internode length were less well correlated with the competition index. Comparing these results with those of controlled laboratory studies gives an indication that on the sites studied, brush competition effects on planted trees are expressed through developmental acclimation to reduced light intensity. Developmental expression of changing nutrient or moisture availability was less evident, but may be confounded by reduced demand or secondary brush canopy effects.
The applicability of available hazard rating systems for mountain pine beetle in lodgepole pine stands of southeastern Wyoming
Authors: Katovich Steven A. , Lavigne Robert J.
Published: November 2007

Five hazard rating systems for Dendroctonusponderosae Hopkins in Pinuscontorta Dougl. stands were compared under nonoutbreak conditions in the Medicine Bow Mountains of southeastern Wyoming. The applicability of these systems, which were designed in other regions of the United States, to P. contorta stands in southeastern Wyoming was investigated. Thirty-two stands in four different age and diameter categories were sampled and rated by each system. Diameter at breast height did not correlate well with phloem width in any of the stands, as implied by the system of Amman and co-workers. A direct phloem width measurement could further refine this system. Periodic growth ratio, used in both the Berryman and Mahoney systems, did not differentiate between fast- and slow-growing trees. Crown competition factor did not positively correlate with increasing diameter at breast height, as implied by the system of Schenk and co-workers. Stand production ranged from 11.1 to 51.0 g wood•m leaf area−2•year−1, applying a modified system based on that designed by Mitchell and co-workers, indicating very high risk in every stand sampled. Further development and validation of hazard rating systems is necessary for improved analysis of risk to P. contorta stands from D. ponderosae in this region.
Tree-ring variation in western larch (Larixoccidentalis) exposed to sulfur dioxide emissions
Authors: Fox C. A. , Kincaid W. B. , Nash III T. H. , Young D. L. , Fritts H. C.
Published: November 2007

A tree-ring analysis was conducted to determine the relationship of sulfur emissions from the lead–zinc smelter at Trail, B.C., to radial growth in western larch (Larixoccidentalis Nutt.). Tree cores were collected from five stands known to have been polluted and from three control stands. Age effects were removed from cross–dated ring-width series by fitting theoretical growth curves and, subsequently, tree-ring chronologies were developed for each stand. We assumed that macroclimatic variation was estimated by the average of the control chronologies and two lagged values thereof. These control variables along with annual estimates of sulfur emissions were used in regression models to predict variation in the tree-ring chronologies from each of the polluted stands. Separate analyses were performed for years before and after installation of two tall stacks, for drought and nondrought years, and for years prior to initiation of smelting. In each case following the initiation of smelting, the variation explained by sulfur decreased with distance from the smelter and, concomitantly, the variation explained by the control variables increased with distance. Furthermore, chronology statistics suggested an increase in synchronous high-frequency variation in chronologies from polluted sites that persisted beyond implementation of pollution controls, which reduced emissions 10-fold.
Sulfur constituents in soils and streams of a watershed in the Rocky Mountains of Alberta
Authors: Mitchell M. J. , David M. B. , Maynard D. G. , Telang S. A.
Published: November 2007

Sulfur constituents of soils and streams were measured in the Marmot Basin watershed of the Rocky Mountains (Alberta). Total S in the soils ranged from 2.5 to 49.8 μmol/g dry mass; carbon-bonded S and ester sulfate were the dominant S constituents (67–86 and 5–32% of total S, respectively), with sulfate ranging from 0.1 to 8.1% of total S. Organic S was 12–21% of total S in stream waters. High concentrations of sulfate (93–355 μmol/L), Ca (763–1075 μmol/L), Mg (387–765 μmol/L), and C (1930–4160 μmol/L) in streams were due to mineral weathering. Atmospheric inputs of S at Marmot Creek were much less important than in forest ecosystems subject to acidic deposition. A tentative budget demonstrated the importance of weathering and organic S in this watershed. Analysis of one tributary (Middle Creek) along an elevation gradient indicated that a portion of the sulfate was retained within the terrestrial portion of the ecosystem in organic forms. The dynamics of these organic S constituents exert a major influence on S flux in some forest ecosystems as a result of their role in mineralization and immobilization processes.
Larch litter and nitrogen availability in mixed larch–spruce stands. I. Nutrient withdrawal, redistribution, and leaching loss from larch foliage at senescence
Authors: Carlyle J. C. , Malcolm D. C.
Published: November 2007

The growth and N status of Sitka spruce on deep peat sites low in available N is improved in the presence of larch. It has been suggested that larch stimulates N mineralization because of high N concentrations in its litter and the large N input resulting from its annual litter fall. However, while larch foliar N concentrations were shown to be high, marked withdrawal and storage in other tree components resulted in a relative and absolute impoverishment of the litter. P and K could be leached from senescing foliage in relatively large amounts, but the potential loss of N was low. Field measurements of throughfall substantiated this finding. Larch seemed extremely conservative in its use of N, suggesting that larch litter does not directly enhance N availability in mixed stands.
Promotion of flowering in white spruce (Piceaglauca) by gibberellin A4/7, auxin (naphthaleneacetic acid), and the adjunct cultural treatments of girdling and Ca(NO3)2 fertilization
Authors: Pharis Richard P. , Tomchuk Debra , Beall Frederick D. , Rauter R. Marie , Kiss Gyula
Published: November 2007

Flowering (production of seed cone buds) of white spruce (Piceaglauca (Moench) Voss) grafts and of 55-year-old trees was significantly promoted by the application of gibberellin A4/7 (GA4/7). Use of GA4/7 accompanied by the adjunct cultural treatment of nondestructive girdling was especially effective. When GA4/7 was injected into a branch, the flowering stimulus was translocated upwards, thereby yielding up to a fivefold increase (72 female cone buds per propagule) in flowering. Clonal propagules sprayed to drip off with GA4/7 + auxin (naphtaleneacetic acid) averaged 116 female cone buds per propagule (a 12-fold increase over controls) with a 100% frequency of flowering. Pollen cone bud production and number of male flowering plants also tended to increase with the most successful flowering treatments. When GA4/7 was applied to 55-year-old trees with nondestructive, overlapping stem girdles and auxin, treatments were significantly effective (6- to 27-fold increases, respectively). When GA4/7 + Ca(NO3)2 was applied to 55-year-old trees, there was a tendency (nonsignificant) to increase (4- to 16-fold) flowering, relative to GA4/7 alone. White spruce, because of its very sporadic flowering and usually nominal response to GA4/7 alone, should be classed as a "recalcitrant conifer species." Use of the GA4/7 plus appropriate adjunct cultural treatments (high temperature, water stress, girdling) and (or) auxin is, thus, recommended if significant flowering and seed cone production is desired.
A heuristic programming approach in estimating efficient target levels in goal programming
Authors: Mendoza Guillermo A.
Published: November 2007

A heuristic programming approach in estimating efficient target levels in goal programming is described. The approach is designed to improve the computational efficiency of defining the decision space of a goal programming problem. An illustrative example is used to describe the procedure. The sample problem used was adopted from a previous study.
Seasonal changes in the cold tolerance of pitch pine
Authors: Berrang P. C. , Steiner K. C.
Published: November 2007

Primary needles, secondary needles, and stems of 1-year-old pitch pine (Pinusrigida Mill.) seedlings were evaluated for cold tolerance on eight dates from October to April. Male and female strobili and elongating shoots of mature trees were evaluated on four dates in May and June. Stems acclimated more rapidly than secondary needles, but were less cold tolerant in midwinter. Secondary needles and primary needles had similar levels of tolerance on most dates. Strobili and emerging shoots were essentially identical in tolerance except on May 17, about 10 days before pollination, when strobili were 5.8–7.7 °C more tolerant than elongating shoots.
Magnetic resonance imaging of wood
Authors: Hall Laurance D. , Rajanayagam Vasanthan , Stewart Wendy A. , Steiner Paul R.
Published: November 2007

A magnetic resonance scanner has been used to obtain images at 0.14 T, based on the water in aspen (Populustremuloides Michx.). In addition to visualization of the expected structural features such as annual growth-rings and knots, several additional features appear that require further study. Kiln-dried wood does not contain sufficient water to give an image, but can do so after impregnation with water.
Fate of 15N-labelled fertilizer applied on snow at two forest sites in British Columbia
Authors: Preston Caroline M. , Marshall Valin G. , McCullough Kevin , Mead Donald J.
Published: November 2007

Fertilizer was applied on snow in January 1981 at 100 kg N•ha−1 as [15N]urea, 15NH4NO3, and NH415NO3 to 11-year-old lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.) at Spillimacheen in the British Columbia interior and as [15N]urea (200 kg N•ha−1) to 13-year-old Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) at Green Mountain, a coastal site in British Columbia. Recovery of labelled N after one growing season was determined in soil and biomass at both sites, and it was also monitored during the growing season in snow and soil at Spillimacheen. At Green Mountain, 5.5% of urea N was recovered in tree biomass, 10.8% in understory, and 33.4% in soil organic N (total recovery 49.7%). Leaching may have contributed to N losses at Green Mountain, but was probably not a direct consequence of the application on snow. At Spillimacheen, total recovery of [15N]urea was 93.3%, with 10.1% in tree biomass, 2.4% in understory, and 80.8% in soil. For 15NH4NO3, recoveries were 5.3% in tree biomass, 2.9% in understory, and 87.0% in soil, for a total of 95.2%. For NH415NO3, recoveries were 1.9% in tree biomass, 3.4% in understory, and 39.1% in soil, for a total of 44.4%. At Spillimacheen, the performance of 15NH4NO3 was comparable to that of urea in tree uptake and soil retention. There were large losses with the NH415NO3 source, however, most likely due to leaching and denitrification during snowmelt. For this reason, fertilization with nitrate on snow is not recommended because of nitrate's susceptibility to leaching, but urea and ammonium sources may be applied under these conditions.