bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonadiabatic quantum dynamics based on a hierarchical electron-phonon model: Exciton dissociation in semiconducting polymers
Authors: Tamura Hiroyuki , Bittner Eric R. , Burghardt Irene
Published: July 2007

A hierarchical electron-phonon coupling model is applied to describe the ultrafast decay of a photogenerated exciton at a donor-acceptor polymer heterojunction, via a vibronic coupling mechanism by which a charge-localized interfacial state is created. Expanding upon an earlier Communication [H. Tamura et al., J. Chem. Phys. 126, 021103 (2007)], we present a quantum dynamical analysis based on a two-state linear vibronic coupling model, which accounts for a two-band phonon bath including high-frequency CC stretch modes and low-frequency ring torsional modes. Building upon this model, an analysis in terms of a hierarchical chain of effective modes is carried out, whose construction is detailed in the present paper. Truncation of this chain at the order n (i.e., 3n+3 modes) conserves the Hamiltonian moments (cumulants) up to the (2n+3)rd order. The effective-mode analysis highlights (i) the dominance of the high-frequency modes in the coupling to the electronic subsystem and (ii) the key role of the low-frequency modes in the intramolecular vibrational redistribution process that is essential in mediating the decay to the charge-localized state. Due to this dynamical interplay, the effective-mode hierarchy has to be carried beyond the first order in order to obtain a qualitatively correct picture of the nonadiabatic process. A reduced model of the dynamics, including a Markovian closure of the hierarchy, is presented. Dynamical calculations were carried out using the multiconfiguration time-dependent Hartree method.
Response to “Comment on ‘Adaptive Q-S (lag, anticipated, and complete) time-varying synchronization and parameters identification of uncertain delayed neural networks”’ [Chaos 17, 038101 (2007)]
Authors: Yu Wenwu , Cao Jinde
Published: July 2007

Parameter identification of dynamical systems from time series has received increasing interest due to its wide applications in secure communication, pattern recognition, neural networks, and so on. Given the driving system, parameters can be estimated from the time series by using an adaptive control algorithm. Recently, it has been reported that for some stable systems, in which parameters are difficult to be identified [Li et al., Phys Lett. A 333, 269–270 (2004); Remark 5 in Yu and Cao, Physica A 375, 467–482 (2007); and Li et al., Chaos 17, 038101 (2007)], and in this paper, a brief discussion about whether parameters can be identified from time series is investigated. From some detailed analyses, the problem of why parameters of stable systems can be hardly estimated is discussed. Some interesting examples are drawn to verify the proposed analysis.
Influence of high pressure on optical impurity spectra
Authors: Renge Indrek
Published: July 2007

Expressions are derived for inhomogeneous band shapes of impurity spectra in highly compressed glassy matrices. Intermolecular guest-host interactions are approximated to isotropic two-body Lennard-Jones 6-12 potentials having different parameters in the ground state and the excited state. Calculated shifts and widths are compared to published values for the absorption spectra of phenanthrene, anthracene [B. Y. Okamoto and H. G. Drickamer, J. Chem. Phys. 61, 2870 (1974)], and several polymethine dyes [G. A. Samara et al., J. Chem. Phys. 37, 1482 (1962)] embedded in polymer hosts and subject to pressures up to 140kbars. The magnitudes of barochromic shifts of the band maxima and the inhomogeneous broadening suggest that the equilibrium coordinates of the excited state are typically less by 5±2%.
The influence of interactions between reagents on the excess in the rate of quenching reaction: Molecular dynamics study
Authors: Litniewski Marek
Published: July 2007

The influence of the interactions between reagents on the excess in the rate coefficient, Δk, for the instantaneous reaction A+B→C+B have been investigated by performing large scale molecular dynamics simulations for simple soft spheres. The simulation method has enabled us to determine the contributions to Δk coming from A-B as well as B-B interactions. The simulations have shown that positive values of Δk that appear both for the liquid and for the Brownian system [M. Litniewski, J. Chem. Phys. 123, 124506 (2005); 124, 114501 (2006)] result from B-B interactions. If B-B interactions were absent, Δk was always negative. The influence of B-B interactions was about three times higher for the Brownian system than for the liquid. A qualitative explanation for the effect has been proposed basing on a simple model and analyzing the influence of B-B interactions on fluctuations in concentrations of reagents. The influence of A-B interactions was completely negligible except for the liquid at short times, for which the cancellation of A-B interaction noticeably decreased Δk.
Colloid-colloid and colloid-wall interactions in driven suspensions
Authors: Krüger Matthias , Rauscher Markus
Published: July 2007

We investigate the nonequilibrium fluid structure mediated forces between two colloids driven through a suspension of mutually noninteracting Brownian particles as well as between a colloid and a wall in stationary situations. We solve the Smoluchowski equation in bispherical coordinates as well as with a method of reflections, both in linear approximation for small velocities and numerically for intermediate velocities, and we compare the results to a superposition approximation considered previously. In particular, we find an enhancement of the friction (compared to the friction on an isolated particle) for two colloids driven side by side as well as for a colloid traveling along a wall. The friction on tailgating colloids is reduced. Colloids traveling side-by-side experience a solute induced repulsion while tailgating colloids are attracted to each other.
Role of the interfacial layer in the efficiency and lifetime of polymeric light emitting devices
Authors: Chin Byung Doo , Kang Nam Su , Yu Jae-Woong , Mu Jo Seong , Lee Jun Yeob
Published: July 2007

The effects of the interfacial layers on the properties of fluorescent polymeric light emitting devices were investigated. The interfacial layer material, poly(9,9′-dioctylfluorene-co-bis-N,N′-(4-ethoxycarbonylphenyl)-bis-N,N′-phenyl-benzidine (BFEC), has uniform surface roughness and high hole mobility upon thermal treatment up to 250 °C. Both for commercially available fluorescent red and green polymeric light emitters, the insertion of a BFEC interfacial layer resulted in a more than 30% increase of efficiency and a three times longer half-lifetime, whereas the blue fluorescent material showed no enhancement of power efficiency and lifetime. We attribute the improved device performance afforded by the interfacial layer to the bilayered devices having a more charge-balanced structure. The facilitated hole injection and electron/exciton blocking of the interfacial layer induced an infinitesimal shift of the recombination region, which was characterized by the electroluminescent spectra of the devices and the photoluminescent spectra of the bilayers.
Synthesis and characterization of an n=6 Aurivillius phase incorporating magnetically active manganese, Bi7(Mn,Ti)6O21
Authors: Zurbuchen M. A. , Freitas R. S. , Wilson M. J. , Schiffer P. , Roeckerath M. , Schubert J. , Biegalski M. D. , Mehta G. H. , Comstock D. J. , Lee J. H. , Jia Y. , Schlom D. G.
Published: July 2007

Epitaxial films of Bi7Mn3.75Ti2.25O21 were prepared to yield a previously unsynthesized material. The superlattice phase is produced by incorporating the magnetoelectric BiMnO3 into the perovskite substructure of the ferroelectric Bi4Ti3O12, a strategy which is hoped to yield previously undiscovered multiferroic materials. X-ray diffraction and transmission electron microscopy (TEM) confirm synthesis of an epitaxial n=6 Aurivillius phase. Magnetization measurements show ferromagnetic behavior with a Curie point of 55K, but electronic polarization measurements show no remanent polarization. Rutherford backscattering spectrometry indicates a channeling minimum χmin of 22%, consistent with the high density of out-of-phase domain boundaries observed by TEM.
Density-functional theory calculations of bare and passivated triangular-shaped ZnO nanowires
Authors: Xu Hu , Rosa A. L. , Frauenheim Th. , Zhang R. Q. , Lee S. T.
Published: July 2007

The authors employ density functional theory within the generalized-gradient approximation to investigate infinitely long [0001] ZnO nanowires. The authors report on atomic relaxations, formation energies, and electronic structure of bare and hydrogen passivated ZnO wires with triangular cross sections. The authors find that surface reconstruction plays an important role in stabilizing the nanowires. The authors have shown that the band gap can be tuned by changing the wire diameter and by passivating with hydrogen. While bare and completely passivated wires are semiconducting, wires with intermediate hydrogen passivation exhibit metallic behavior.
Effect of recombinant factor VIIa variant (NN1731) on platelet function, clot structure and force onset time in whole blood from healthy volunteers and haemophilia patients
Authors: BROPHY D. F. , MARTIN E. J. , NOLTE M. E. , KUHN J. G. , CARR JR M. E.
Published: July 2007

Summary.  NN1731 is a novel variant of recombinant factor VIIa (rFVIIa) that binds to activated platelets, but has greater enzymatic activity than rFVIIa in generating FXa and thrombin. The effect of NN1731 on clot structure and platelet function was characterized ex vivo in whole blood from healthy volunteers and haemophilic patients. Blood samples from six healthy volunteers, nine haemophilia A patients with and without inhibitors and one acquired haemophilia A patient, were spiked with increasing concentrations (0.32, 0.64 and 1.28 μg mL−1) of rFVIIa and NN1731. Platelet contractile force (PCF) or platelet function, clot elastic modulus (CEM) or clot structure, and force onset time (FOT) or the thrombin generation time (TGT) were determined using the Hemodyne Hemostasis Analysis System (HAS™). Baseline PCF, CEM and FOT values in patients were abnormal compared to healthy volunteers’ baseline values. Overall, haemophilia blood samples with or without inhibitors spiked with NN1731 had significantly greater PCF, CEM and shorter FOT values relative to samples spiked with corresponding doses of rFVIIa. The variability in response to treatment between patients was greater with rFVIIa compared to NN1731. At 1.28 μg mL−1 (90 μg kg−1), NN1731 normalized PCF, CEM and FOT in nine of 10 patients, while rFVIIa normalized these parameters in four of 10 patients. Increasing in vitro concentrations of NN1731 normalized platelet function, clot structure and thrombin generation consistently in haemophilia blood with or without inhibitors. NN1731 may be a promising haemostatic agent for patients with bleeding disorders. These results should be confirmed in an in vivo study.
Reduced immunostaining for c‐kit receptors in mucosal mast cells in inflammatory bowel disease
Authors: Farhadi Ashkan , Keshavarzian Ali , Fields Jeremy Z , Jakate Shriram , Shaikh Maliha , Banan Ali
Published: July 2007

Background and Aim:  The deleterious effects of stress in inflammatory bowel disease (IBD) have been attributed to activation of the brain–gut axis (BGA) and its end effectors, mast cells (MC). We previously showed that cold pressor stress test (CPT) results in increased activation and degranulation (but not increased proliferation) of mucosal MC, mitochondrial damage to epithelial cells and mucosal protein oxidation in both healthy controls and IBD patients. These changes are more marked in IBD patients. This increased activation of MC in IBD could be due to (i) greater activation of the BGA or (ii) inherited or acquired abnormalities in mucosal MC. In the current study we investigated the latter possibility.

Methods:  To assess the effects of stress on mucosal MC in patients with IBD, seven controls and 15 subjects with inactive IBD underwent 5 consecutive days of CPT to activate the BGA. Endoscopic mucosal biopsies of the distal sigmoid colon were taken during unprepared sigmoidoscopy before the first CPT and after the last CPT, and formalin‐fixed samples were stained for both MC granules (MCg) and for the c‐kit receptor, which is present on MC membranes (MCm). Mast cell degranulation was assessed using electron microscopy.

Results:  Mast cell granule staining suggested that IBD subjects do not have a significantly different number of MC compared with controls, either before or after stress. Mast cell membrane staining, in contrast, suggested that MC c‐kit immunostaining was significantly reduced – at both baseline (P = 0.01) and post stress (P = 0.04) samples – in IBD patients compared to controls. MC c‐kit immunostaining was independent of stress‐induced MC degranulation. There was no significant change in MC number as a result of the stress intervention using either staining method in both groups.

Conclusion:  These data support our previous report that the size of the mucosal MC population in patients with inactive IBD is not altered by disease or by stress, yet MC in IBD are different (fewer c‐kit receptors) and respond differently (greater activation) than MC in control subjects. It remains to be seen whether this abnormality is an inherited or acquired one and to identify its role and mechanism in tissue injury in the pathogenesis of IBD.
Pheochromocytoma with abscess
Authors: Inoue Ryuta , Hisasue Shin‐Ichi , Kunishima Yasuharu , Masumori Naoya , Itoh Naoki , Tsukamoto Taiji
Published: July 2007

Abstract:  We report a case of a 34‐year‐old man who suffered from pheochromocytoma with an abscess in the right adrenal. He presented with a high fever and back pain. He also had some episodes of headache and palpitation. Serum and urine catecholamine levels were elevated. From computed tomography and 123I‐meta‐iodobenzylguanidine scans, his condition was diagnosed as pheochromocytoma with an abscess. Two pairs of blood cultures yielded Streptococcus agalactiae, which was believed to be derived from dental caries. He was successfully treated with antibiotics for his abscess and right adrenalectomy for his pheochromocytoma.
The aromatic cluster in KCHIP1b affects Kv4 inactivation gating
Authors: Van Hoorick D. , Raes A. , Snyders D. J.
Published: July 2007

The KChIP1b splice variant has been shown to induce slow recovery from inactivation for Kv4.2 whereas KChIP1a enhanced the recovery. Both splice variants differ only by the insertion of the exon1b, rich in aromatic residues (5/11). We analysed in detail the modifications of Kv4.2 gating induced by the KChIP1b splice variant and the role for the aromatic cluster in KChIP1b in inducing these changes. By substituting alanine for the aromatic residues individually or in combination, we could convert the KChIP1b recovery behaviour into that of KChIP1a. The replacement of one or two aromatic residues resulted in a partial restitution of the KChIP1a recovery behaviour. When three aromatic residues were replaced in the exon1b, the recovery from inactivation was fast with time constants that were similar to those obtained with KChIP1a. Moreover, similar findings were observed for closed state inactivation and for the voltage dependence of inactivation. Thus, reduction of the side chain bulkiness in exon1b resulted in the conversion of the KChIP1b phenotype into the KChIP1a phenotype. These results indicate that the aromatic cluster in exon1b modulates the transitions towards and from the closed inactivated states and the steady state distribution over the respective states.
A Whole-Genome Association Study of Major Determinants for Host Control of HIV-1
Authors: Fellay Jacques , Shianna Kevin V. , Ge Dongliang , Colombo Sara , Ledergerber Bruno , Weale Mike , Zhang Kunlin , Gumbs Curtis , Castagna Antonella , Cossarizza Andrea , Cozzi-Lepri Alessandro , De Luca Andrea , Easterbrook Philippa , Francioli Patrick , Mallal Simon , Martinez-Picado Javier , Miro José M. , Obel Niels , Smith Jason P. , Wyniger Josiane , Descombes Patrick , Antonarakis Stylianos E. , Letvin Norman L. , McMichael Andrew J. , Haynes Barton F. , Telenti Amalio , Goldstein David B.
Published: July 2007

Understanding why some people establish and maintain effective control of HIV-1 and others do not is a priority in the effort to develop new treatments for HIV/AIDS. Using a whole-genome association strategy, we identified polymorphisms that explain nearly 15% of the variation among individuals in viral load during the asymptomatic set-point period of infection. One of these is found within an endogenous retroviral element and is associated with major histocompatibility allele
human leukocyte antigen
(
HLA
)–
B*5701
, whereas a second is located near the
HLA-C
gene. An additional analysis of the time to HIV disease progression implicated two genes, one of which encodes an RNA polymerase I subunit. These findings emphasize the importance of studying human genetic variation as a guide to combating infectious agents.
Locating changeable message signs for advanced traffic information and management systems
Authors: Fu Liping , Henderson Jeffrey , Li Shuo
Published: July 2007

This paper presents an optimization model for locating changeable message signs (CMSs) on an integrated freeway-arterial network. Compared with existing models, the proposed model represents a well-balanced compromise between computational efficiency required to solve problems of realistic size, and model realism to ensure the quality of solutions. The model has three unique features: (1) it recognizes that locating CMSs is a planning problem that must take into account both current and future needs and benefits, (2) it evaluates benefits of CMSs over multiple time periods with different traffic distributions, and (3) it explicitly considers inherent variations in incident characteristics across links and over time. A sensitivity analysis is performed to examine the potential impacts on optimal CMSs locations resulting from uncertainties in various input parameters, such as traffic demand, incident attributes, and driver behaviour. Lastly, the proposed model is applied to the Highway 401 express-collector freeway system in Toronto for relocating the existing CMSs.Key words: changeable message signs (CMSs), location optimization, traffic assignment, queuing theory.
Germination and Development of Lodgepole Pine Pollen inVitro
Authors: Ho Rong Hui , Sziklai Oscar
Published: July 2007

Mature pollen grains of lodgepole pine (Pinuscontorta Dougl.) were incubated in solutions of sucrose, indoleacetic acid (IAA), and stock solution A containing boric acid, calcium nitrate, magnesium sulfate, and potassium nitrate. Sucrose solution did not stimulate pollen germination but did inhibit pollen tube growth. A slight promotion of tube growth resulted from an IAA solution, but no increase was obtained in germination percentage. Stock solution B (diluted one-tenth of concentration of stock solution A) was optimum for pollen germination and pollen tube growth. Two basic types of pollen tube development and pollen tube branching occurred. An abnormal development of the pollen tube, protruding through the saccus, was recorded. After 5 days of incubation in stock solution B, the generative cell divided into the stalk cell and the body cell, and 2 days later the body nucleus divided to form two male nuclei of either equal or unequal sizes.
Influence des nœuds sur les forces de coupe dans le sciage du bois
Authors: St-Laurent André
Published: July 2007

In this study, effects of knots on cutting forces in sawmilling, cuts were made perpendicular to the grain in wood above 32% moisture content in order to simulate the action of band saw teeth. An apparatus with a single tooth was used. In white pine (Pinusstrobus) and red pine (Pinusresinosa), the main cutting force is greater when the growth rings are oriented tangentially than when they are oriented radially. In yellow birch (Betulaalleghaniensis), the principal force is greatest in the case of radial orientation. Wood with a specific gravity of 0.70 requires almost twice the principal cutting force of that required for wood with a specific gravity of 0.38. We have discovered that, in comparison with normal wood, medium compression wood of white spruce (Piceaglauca) brings about an increase of 35% in the principal cutting force. When a knot is cut, the principal force is approximately the same for the hardwood and softwood species studied. Because this is not the case in clear wood, the knot of a softwood such as white spruce requires approximately four times the principal force as that in clear wood. The knot of a hardwood such as the sugar maple (Acersaccharum) requires almost twice the clear wood principal force. Occasionally peak lateral forces equal to the principal cutting force in clear wood will cause a tooth to deviate in the immediate vicinity of a knot. It has been demonstrated that, in the case of a band saw, a deviation of at least 5 mm in the kerf may result. If the knot is at all large, it is obvious that several successive teeth must cut through it and the deviation of the blade will thus be greater. The losses through subsequent planing, necessary to correct the sawn surface, will thus be considerable.
Pertes d'azote par volatilisation ammoniacale après fertilisation en forêt de pin gris
Authors: Carrier D. , Bernier B.
Published: July 2007

In a field study, percentage of nitrogen lost as ammonia from a jack pine (Pinusbanksiana Lamb.) soil increased with increasing rates of urea application between 112 and 448 kg N/ha. After 7 days, losses amounted to 18–28% of a 224 kg urea-N/ha application, representing 60–87% of the total losses measured over a 6-week period. Maximum volatilization rates occurred between the third and the fifth day after fertilization, at which time urea hydrolysis was virtually complete. Negligible ammonia losses were measured in plots treated with ammonium sulfate, ammonium nitrate, and sulfur-coated urea. Applying superphosphate with urea markedly depressed ammonia volatilization, an effect which was enhanced by a joint application of K2SO4•MgSO4. Reduction of volatilization by artificial precipitation was significant and increased with increasing precipitation when the latter was applied soon after fertilization; decreases in volatilization were then related to the amount of residual urea subject to diffusion into the humus layer or to leaching towards the underlying soil horizons.
Comparisons of Environmental Ordinations with Principal Component Vegetational Ordinations for Sets of Data Having Different Degrees of Complexity
Authors: Jeglum J. K. , Wehrhahn C. F. , Swan J. M. A.
Published: July 2007

Data from a survey of lowland, mainly peatland, vegetation were subjected to environmental ordination based on measurements of water level and water conductivity, and to vegetational ordination derived from principal component analysis (P.C.A.). Analyzed were the total set of the data ("all types"), half sets ("nonwoody" and "woody types") and quarter sets (stands of "marshes", "meadows", "shrub fens", and "other woody types"); the number of distinct physiognomic groups in a set of data, and presumably the amount of contained heterogeneity, decreased at each segmentation.The effectiveness of the ordination models was tested by correlating measured distances in two-dimensional ordination models with 2W/(A + B) indices of vegetational similarity for randomly selected pairs of types or stands. As the physiognomic complexity decreased, the effectiveness of the P.C.A. vegetational ordination increased whereas that of the environmental ordination decreased. The environmental ordination seemed most appropriate to the data encompassing high complexity (total data set), while the P.C.A. vegetational ordination seemed most appropriate to data with low complexity (quarter sets of the data).
Rooting of Picea Cuttings in Plastic Tubes
Authors: Rauter R. Marie
Published: July 2007

Experiments to determine the rooting ability of cuttings from 3-year-old seedlings of Piceaglauca, P. schrenkiana, and P. schrenkiana × glauca; and 5-year-old material of P. mariana were established in the spring of 1969. The cuttings were made from the latest year's growth with a heel of old wood. They were placed in plastic tubes, arranged in flats, and set into a chamber where high relative humidity was maintained by means of an intermittent mist. Parts of some experiments were conducted over a buried heating cable.The results show differences in rooting ability due to species, populations, individuals, and addition of bottom heat. P. glauca, P. schrenkiana, and the hybrid showed very good rooting ability, averaging 77% or better overall. P. mariana had a lower rooting percentage (44%), but there were some individuals within this species which rooted very well.
Vertical Orientation of Red Maple (Acerrubrum L.) Roots
Authors: Wilson Brayton F.
Published: July 2007

Experimental studies of large (diameter >1 mm), horizontally growing, red maple root tips showed that several factors affected their vertical orientation. If reoriented upwards into loose vermiculite, the roots showed positive geotropism and corrected downwards to a final angle of −10° to −20° from the horizontal. The final angle approached horizontal in more compacted vermiculite. The root tips showed no negative geotropic response, but they tended to bend upwards after having been deflected downwards. Some roots bent upwards after having grown from loose to more compacted vermiculite. These experimental results can be interpreted in terms of the orientation of red maple roots under natural conditions.
Capital Deepening and Technological Change: The Canadian Pulp and Paper Industry 1940–1960
Authors: Manning G. H. , Thornburn G.
Published: July 2007

The pulp and paper industry is generally considered the most technologically progressive of the forest industries. A study employing Solow's method indicated a rise in the index of technological change of 50% between 1940 and 1960. This compares with a 547% increase for the chemical industry. Derivation of the capital production function for the pulp and paper industries shows that all increases in productivity, 1940–1960, were due to change in technology. There is also some indication that optimal plant size has been reached.
The Kinetics of Water Absorption in Stratifying and Nonstratifying Noble Fir (Abiesprocera Rehd.) Seeds
Authors: Edwards D. G. W.
Published: July 2007

Rate of water absorption by empty and filled noble fir (Abiesprocera Rehd.) seeds was faster for 25 °C (nonstratifying) seeds than for 5 °C (stratifying) seeds during the initial stages. After the first 3 days water uptake by empty seeds essentially ceased at 25 °C, but absorption was continuing at 5 °C after 28 days, water levels averaging nearly 60% higher than at 25 °C. Water uptake by empty seeds was used to express absorption by the seedcoat of filled seeds. When germination was first seen at 25 °C, the seedcoat contained 60% of all the water in the seed.Differences in absorption between stratifying and nonstratifying filled seeds were more obscure because of absorption by the internal tissues. At 25 °C, water uptake by filled seeds followed the three generally recognized phases.The transfer of empty seeds from 25 to 5 °C upset the moisture equilibrium established after 15 days at 25 °C, but although water uptake resumed, the water levels after 45 days were not as high as for empty seeds exposed continuously to 5 °C for 28 days. This was interpreted as indicating that the imbibant had undergone some change which modified the forces of hydration.
Development of Ectomycorrhiza on Red Pine Roots
Authors: Khatamian H. , Hilton R. J.
Published: July 2007

Roots of 4-year-old Red Pine (Pinusresinosa Ait.) growing against glass panes of the Guelph rhizotron rapidly developed an ectomycorrhizal growth in August and September of 1970. Development did not extend below 40 cm from the soil surface and was retarded as soil temperature fell below 20 °C. Soil moisture in the 9–11% range supported mycelium growth. Analysis of pine leaves did not indicate an unusually low content of major nutrients but soil analysis at several depths showed low nitrogen and only traces of phosphorus.
Detection of Discolored and Decayed Wood in Living Trees Using a Pulsed Electric Current
Authors: Skutt H. Richard , Shigo Alex L. , Lessard Ronald A.
Published: July 2007

The resistance to a pulsed electric current decreased sharply as the tips of stainless steel electrodes entered discolored and decayed tissues in living deciduous trees. The apparatus delivering the pulsed electric current is described.
Precocious Flowering of Black Cherry Related to Altitudinal Source
Authors: Farmer Jr. R. E. , Barnett P. E.
Published: July 2007

Black cherry (Prunusserotina Ehrh.) seedlings from low elevation sources (300–490 m) in the southern Appalachian mountains formed floral buds during their initial growing season; seedlings from high elevations (1150–1475 m) did not exhibit first year floral initiation.
A Test of Close-Spaced, Short-Rotation Culture of Black Cottonwood
Authors: Heilman P. E. , Peabody Jr. D. V. , DeBell D. S. , Strand R. F.
Published: July 2007

Yield of black cottonwood (Populustrichocarpa Torr. and Gray) in 2-year rotations was affected in the first rotation by spacing and fertilization. Closest spacing (0.30 × 0.30 m) resulted in highest yield in the first rotation whereas in the second rotation, yield was not significantly affected by spacing. The average fresh weight yields were 13.4 tons/hectare/year in the first harvest and 20.9 tons/hectare/year in the second harvest. Initial fertilization with both N, and N, P, and K fertilizers improved growth in the first harvest but not in the second. During the first year, triazine herbicides controlled weeds but caused slight damage to the plants. Although there were no significant differences in yield between the herbicides, atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine) reduced survival and first year height growth below that obtained with propazine (2-chloro-4, 6-bis[isopropylamino]-s-triazine) or simazine (2-chloro-4, 6-bis-ethylamino-s-triazine). Yield results and limited pulping studies show that short rotation black cottonwood has potential value for pulp fiber production.
Extruded Peat Cylinders: Their Physical Characteristics as Affecting Tree Seedling Growth and Greenhouse Drought Tolerance
Authors: Mitchell D. L. , Hocking D. , Kay W. C.
Published: July 2007

Seedlings were grown in containers formed by extruding a peat–water mixture into flexible plastic tubing. The reduction in particle size of the peat that occurs during extrusion improved the rate of moisture absorption and decreased the rate of moisture loss. A range of peat densities of extruded peat cylinders (sausages) was prepared through control of the water content in the feed mixtures. Seedlings grown in sausages show decreased growth as the peat density is increased. Compared to rigid tubes filled with loose peat, seedlings in sausages are less subject to drought.
Aspects of Chemical Variability in Forest Humus Layers Under a Mature Western Hemlock – Western Red Cedar Stand
Authors: Lowe L. E.
Published: July 2007

Analysis for organic components of L, F and H horizons at six sites in a forest stand, yielded coefficients of variation ranging from 3 to 15% for most characteristics studied. Variation in proportions of organic constituents within each horizon, was in general markedly less than the variation in total amounts of organic matter, as indicated by horizon thickness.The results suggest that fewer samples are needed to characterize the distribution of organic constituents within and between the organic horizons of a single forest stand, than are required for estimates of total biomass.
A Photoperiod Response in Germination of Western Hemlock Seeds
Authors: Edwards D. G. W. , Olsen Patricia E.
Published: July 2007

Unstratified and stratified seeds of western hemlock (Tsugaheterophylla) germinated fastest under 4-h photoperiods and slowest under 24-h photoperiods at 20 °C. No differences were found between total darkness and an 8-h photoperiod. Stratification tended to reduce the degree of response to photoperiod. Several indices of germination rate and capacity were compared.
Foliar Nutrient Concentration Differences Between Provenances of Douglas Fir and Their Significance to Foliar Analysis Interpretation
Authors: Driessche R. van den
Published: July 2007

Foliar nutrient concentration differences between provenances, and the relationship between foliar nutrient levels and provenance growth was examined in Douglas fir (Pseudotsugamenziesii (Mirb.) Franco) from the coastal region of British Columbia.In the first experiment differences in foliar nutrient concentrations among four provenances of 3-year old plants, ranged from 8 to 18%. The relationships between these provenances differed according to whether needle, or whole plant nutrient concentrations were considered.In the second experiment 2-year old plants of three provenances, grown under four fertilizer regimes, at each of three nurseries, showed that differences in growth and foliar nutrient concentrations between provenances were affected by nursery. The degree of correlation between shoot length and foliage nutrient concentration varied according to provenance. Coefficients for the regression of shoot length on foliar N and K differed between provenances even when provenance foliar N and K levels were similar. It was suggested that the relationship between foliar nutrient concentrations and shoot length may differ between provenances.
The Influences of Comminution and Compression of Substratum Peat on Growth and Drought Tolerance of Lodgepole Pine Container Seedlings
Authors: Hocking D. , Mitchell D. L.
Published: July 2007

Lodgepole pine (Pinuscontorta Dougl. var. latifolia Engelm.) seedlings were grown in three peat substrata: (1) tubes filled with horticultural grade peat; (2) tubes filled with comminuted peat; and (3) tubes filled with comminuted, compressed peat. Treatment (3) gave the greatest seedling dry weights after 14 weeks in a drought tolerance experiment. Surviving seedlings grown in compressed, comminuted peat showed the greatest increase in total dry weight. These results were attributed tô compression of the peat.
Change in Resistance of Lodgepole Pine to Mountain Pine Beetle Between 1965 and 1972
Authors: Shrimpton D. M. , Reid R. W.
Published: July 2007

In 1965, 100 lodgepole pines (Pinuscontorta Dougl. var. latifolia Engelm.) in each of two areas near Radium, B.C. were graded for resistance to mountain pine beetle (Dendroctonusponderosae Hopk.) by evaluating their response to inoculation with a fungus transported by the mountain pine beetle. In 1972, mortality of these trees due to mountain pine beetle or other causes was determined, trees were inoculated and the resistance of each was again evaluated. Most trees nonresistant in 1965 had been killed by the mountain pine beetle by 1972, whereas most trees rated resistant in 1965 were still alive and were again rated resistant.
Microstrobili of Lodgepole Pine
Authors: Ho Rong Hui , Owens John N.
Published: July 2007

The long-shoot terminal bud of lodgepole pine (Pinuscontorta Dougl.) consists of spirally arranged cataphylls which may be sterile or fertile. The cataphylls which bear microstrobili are just above the most proximal few sterile cataphylls. The average number of microstrobili per shoot is 15; bud scales per microstrobilus is 7.8; microsporophylls per microstrobilus is 137.9; and pollen grains per microsporangium is 2103. It is estimated that each microstrobilus produces about 590 000 pollen grains and each shoot about 8.9million grains.
Free Amino Acids in Grand Fir Needles and the Effects of Different Forms of Foliar-applied Nitrogen
Authors: Carrow J. Roderick
Published: July 2007

Needles of grand fir, Abiesgrandis (Dougl.) Lindl., were analyzed to determine: (1) how various forms of nitrogen fertilizer affect amino acid composition, and (2) whether amino acids in the needles differ from those in stem bark (determined in a previous study). Young grand fir were grown in a shadehouse and free amino acids were analyzed four times from May to August, using thin-layer electrophoresis and chromatography. The effects of foliar-applied nitrogen fertilizer on needle amino acids depended on the form of nitrogen. Urea or ammonium nitrate promoted large increases in arginine, glutamine, alanine, lysine, and γ-amino butyric acid, whereas calcium nitrate caused smaller increases. The occurrence of several trace amino acids also varied with the form of nitrogen. Comparison of needle amino acids with those in the stem of unfertilized trees revealed that levels of total amino nitrogen, arginine, glutamic acid, and glutamine were much greater in the stem bark than in the needles, but levels of γ-amino butyric acid and alanine were higher in needles. Traces of aspartic acid, ornithine, and tyrosine were found in the needles, but not in the stem.
Brown Mould (Cephaloascusfragrans) on Wood, its Significance and History
Authors: Roff J. W.
Published: July 2007

Conflicting reports of the occurrence of Cephaloascusfragrans Han. relate to the varied appearance and color of this mould upon wood and the fact it may be overgrown by other, more vigorous fungi. C. fragrans presents a problem in the commercial treatment of lumber, as it is not inhibited by formulations of chlorinated phenols presently used to prevent mould and sap stain.
Sulfur dioxide injury, sulfur content, and stomatal conductance of birch foliage
Authors: Biggs A. R. , Davis D. D.
Published: July 2007

Seedlings of three birch species were exposed biweekly to 2358 μg/m3 (0.9 ppm) SO2 for 2 h from May to September 1977. Leaf sulfur content of the birch foliage increased following exposure to SO2, but sulfur accumulation was not correlated with visible injury. Relative susceptibility was significantly correlated with preexposure leaf conductance rates of Betulanigra L. and B. papyrifera Marsh., but not for B. pubescens Ehrh. Leaf conductance rates were not correlated with sulfur accumulation.
Comparative stand development in an old-growth Douglas-fir (Pseudotsugamenziesii var. glauca) forest in western Montana
Authors: Tesch Steven D.
Published: July 2007

The composition, structure, and reproductive dynamics of two old-growth Douglas-fir (Pseudotsugamenziesii var. glauca (Beissn.) Franco) stands, located on opposing north and south aspects, were analyzed to reconstruct their past developmental patterns. Results indicate that the north aspect stand developed an even-aged structure initially and shifted to an uneven-aged structure over time. The theory of monospecific dominance by the climax species is supported on the north aspect as Douglas-fir maintains the highest importance value of all species present. The competitive exclusion principle appears inappropriate in this case as lodgepole pine (Pinuscontorta Dougl.), an intolerant, seral dominant, is reproducing successfully under the old-growth canopy. The south aspect stand has developed an uneven-aged structure and maintains it as harsh environmental conditions limit reproductive success to favorable microsites, precluding complete canopy closure.
A cut-branch technique for introducing solutions into conifers
Authors: Puritch George S. , McMullan Eleanore E.
Published: July 2007

A new method was presented in which solutions were introduced into conifers via cut branches. This technique avoided the necessity of wounding and weakening the stem as occurs in stem injection techniques. Uptake through the branches followed a curvilinear pattern, declining with time. Branches took up solutions for as long as 750 h, but the main volume was taken in over the first 250 h. Recutting twigs during the reduced stages of uptake failed to return the uptake rate to its original value.The cut-branch technique was used to introduce gibberellin 4/7 (GA4/7) into Tsugaheterophylla and Abiesamabilis seedlings. Tsugaheterophylla responded by producing female cones the following year, although A. amabilis did not show a cone production response. Addition of the reducing agents ascorbic acid – sodium isoascorbate enhanced uptake of both water and GA4/7 solution and caused no deleterious effects to the seedlings. Exudation of resin prevented solution uptake in two pine species.
Wildfire prevention engineering systems
Authors: Pottharst Ed , Mar Brian W.
Published: July 2007

The role of engineering in wildfire prevention and management was examined from a systems viewpoint. A model was developed to describe the causality between engineering actions such as product innovation, equipment maintenance, and system modification and the reduction in wildfires. Case studies of railroad- and equipment-caused wildfires were developed to demonstrate how the model coefficients can be estimated using existing wildfire statistics, and how the model can be enhanced with additional wildfire data. These data indicate not only how much new products can reduce wildfire caused by the unimproved product, but also show that maintenance is required to keep up these reductions over time.
The use of overlays in site quality mapping
Authors: Ferguson Bruce K.
Published: July 2007

When a sizable forested area is to be managed, some kind of map site quality for that area is necessary so that a determination can be made of the amount and distribution of lands having different levels of site quality. A manual method for chloropleth mapping of red oak site quality using soil-site studies was developed. It mapped site quality as a function of slope gradient, slope position, slope orientation, and soil depth. It consisted of selecting the soil-site study, establishing a uniform mapping format, classifying the independent variables into mapped or mappable ranges, mapping each independent variable separately, and manually overlaying these maps to produce a single site-quality map. The accuracy of the result, the usefulness of the method, and the possibility of different procedures in other studies are discussed.
Organic matter and major elements of the forest floors and soils in subalpine balsam fir forests
Authors: Lang Gerald E. , Cronan Christopher S. , Reiners William A.
Published: July 2007

Forest floors, fallen branches and fallen tree boles were sampled in 13 balsam fir (Abiesbalsamea (L.) Mill.) stands in the subalpine zone (1220–1450 m) of the White Mountains in New Hampshire, U.S.A. These 13 stands were distributed in three sites of contrasting exposure, slope, and rockiness. Soil pits were excavated in three of the stands representing each of the three sites. The ash-free dry weights and major elemental contents of the forest floor and dead wood were compared along chronosequences following natural disturbances, between sites, and with other forest types. No significant trends in these components were found along chronosequence comparisons. For sites that are dissimilar in terms of physical position on the landscape and in the appearance of the trees, compensating biotic and abiotic factors apparently underlie the convergence in forest floor and soil characteristics, thereby eliminating site differences as well. The forest floor is massive; ash-free dry weight averages 92 200 kg•ha−1. Total soil profile ash-free weight is 323 600 kg•ha−1. The forest floor and mineral soil horizons are unusually rich in nitrogen and phosphorus, with weighted average ash-free nitrogen and phosphorus concentrations of 2.42 and 0.23%, respectively, in the forest floor. Total nitrogen and phosphorus contents of the forest floor are 2300 and 217 kg•ha−1, respectively. The weight and nitrogen and phorphorus contents of the fir forest floor are greater than that found in other regional forests and coniferous forests in general.
Calorie values of eight New Hampshire forest tree species
Authors: Musselman Keith , Hocker Jr. H. W.
Published: July 2007

Caloric values (in calories per gram of dry weight (1 cal = 4.184 J)) were determined for bole and branches (with and without bark), and for foliage of Acersaccharum Marsh., Betulaalleghaniensis Britton, Fraxinusamericana L., Acerrubrum L., Quercusrubra L., Betulapapyrifera Marsh., Pinusstrobus L., and Populustremuloides Michx. For each of the hardwood species, caloric values did not differ significantly between samples with and without bark or between bole and branch components (when with and without bark data were pooled). For Pinusstrobus L. there was a 5% significant difference between branch with bark and branch without bark samples and between pooled bole and pooled branch components. Significant differences of up to 8% occurred among species for pooled bole and pooled branch components, and differences of up to 12% occurred among species for foliage samples, although these were not tested statistically.
Fertilisation azotée en forêt de pin gris (Pinusbanksiana) II. Variations de la masse foliaire et des éléments nutritifs du feuillage de pin gris et de quelques espèces du sous-bois
Authors: Camiré C. , Bernier B.
Published: July 2007

Fall or spring applications of six different nitrogen fertilizers (urea, sulfur-coated urea, urea-formaldehyde, ammonium nitrate, ammonium sulfate, and calcium nitrate) at a rate of 224 kg N/ha in an 18-year-old jack pine stand induced a very rapid increase of nitrogen concentration in current year and 1-year-old needles, as well as in weight of current year needles. In the latter, nitrogen content (concentration × weight) increased more than 100% the 1st year following fertilization in the ammonium sulfate and the ammonium nitrate treatments applied in spring. Response did not last more than 2 years. Foliar analysis of other elements (P, K, Ca, Mg, and Mn) revealed a reduction of P concentration in the needles sampled the first fall after treatment together with a reduction of Ca and Mn in the current foliage of the second and third seasons after treatment. Changes in nitrogen concentration in Kalmiaangustifolia L. and particularly in Solidagopuberula Nutt. were in good correlation with those observed in jack pine needles.
Effects of artificial conifer foliage on collection of precipitation and nutrients in coastal British Columbia
Authors: DeCatanzaro Jennifer B. , Binkley Dan
Published: July 2007

Precipitation collectors with artificial conifer foliage collected 6–8% more water and 23–143% more calcium, potassium, ammonium, nitrate, and sulfate than collectors without foliage. Moisture condensation and aerosol impaction need to be considered in studies of forest ecosystems.
The importance of fertility and physical characteristics of soil in early development of red alder seedlings grown under controlled environmental conditions
Authors: Elliott D. M. , Taylor I. E. P.
Published: July 2007

Fertilized and unfertilized seedlings of red alder (Alnusrubra Bong.) were grown in pots containing coarse sand, loam, or loam and sand (1:1, w/w) and kept in a growth chamber. Height growth did not differ between provenances but, like dry weight accumulation, it increased with fertilization and was lower in sand than in loam and the mixture. The root/shoot dry weight ratio of fertilized seedlings was lower than that of unfertilized seedlings and was greater in sand than in the other media. Differences in dry weight and root/shoot dry weight ratio were observed between provenances, but these could not be related to differences in geographic location of the provenances examined.Nodulation was affected little by variations in the rooting environment. The physical nature of roots produced by seedlings varied with the type of growth medium and with fertilization. These differences, and other effects brought about by the type of growth medium and by fertilization, were associated mainly with differences in aeration and, in the absence of fertilization, with the nutrient status of the different growth media.