bluuebunny/crossref_metadata_2025 huggingface dataset:
Active earth thrust by backfills subject to a line surcharge
Authors: Greco Venanzio R
Published: October 2005

The current analytical solution for the thrust computation when a line of vertical surcharge acts on the backfill behind a wall assumes the soils to be simultaneously elastic, for calculating part of the thrust, and in the active state of failure, for calculating the remaining part of the thrust. This paper gives a coherent analytical solution based on Coulomb's approach. The position of the active thrust is also given in a simple analytical form and compared with the approximate solution of Terzaghi.Key words: active earth force, cantilever walls, lateral pressure, active condition.
Zeta potential of clay minerals and quartz contaminated by heavy metals
Authors: Kaya A , Yukselen Y
Published: October 2005

Laboratory and in situ test results show that electrokinetic decontamination is a promising subsurface decontamination method. However, it has also been reported that several problems arise, such as reverse flow and pH gradient across the anode and the cathode during the electrokinetic decontamination process. Variation in pH alters the zeta (ζ) potential of soils, which is one of the factors affecting the efficiency of contaminant removal by the electrokinetic method. The magnitude of the ζ potential controls the fluid flow rate, whereas its sign controls the flow direction. However, research on how the ζ potential of soils changes under various chemical conditions is limited. In this paper, the effect of pore-fluid chemistry on the ζ potential of kaolinite, montmorillonite, and quartz powder is determined with NaCl, LiCl, CaCl2·2H2O, MgCl2·6H2O, CuCl2, CoCl2, ZnCl2, AlCl3, and Pb(NO3)2. The test results reveal that the ζ potential of the minerals with alkali and alkaline-earth metals changes according to the diffuse electrical double-layer theory. The hydrolyzable metal ions produce two points of zero charge (PZCs), one of which is that of the soil; and the other, that of hydrolyzable oxide. The ζ potential of minerals with hydrolyzable metal ions becomes increasingly positive and reaches its maximum value at neutral pH. It then decreases and again reaches very negative values at alkaline pH values (pH ∼ 10), depending on ion concentration and the bulk precipitation pH of hydrolyzable metals as hydrolyzable oxides. On the basis of the results of this study, it is recommended that the ζ potential of the soils be determined before electrokinetic decontamination.Key words: alkaline-earth metals, electrokinetic decontamination, heavy metals, zeta potential.
Fully coupled thermohydraulic modelling of the sealing bulkheads and adjacent rock in a full-scale underground test
Authors: Guo Ruiping , Martino Jason , Dixon David
Published: October 2005

The Tunnel Sealing Experiment (TSX) was a two-phase international project funded by Canada, Japan, France, and the United States. The first phase was pressurizing the TSX chamber to 4 MPa to investigate the ability of clay and concrete bulkheads to reduce hydraulic flows. The second phase involved circulating heated water through the chamber to evaluate the influence of elevated temperature on the performance of the bulkheads and adjacent rock. A numerical analysis to simulate thermohydraulic evolution of the bulkheads and surrounding rock of the TSX was conducted to help in understanding the physical test process and the interaction between heat and pore pressure evolutions. The simulated rock temperature matched the measured data quite well; however the simulated bulkhead temperatures were greater than the measured temperatures. The difference may have been caused by entrapped air or formation of microchannels in the chamber sand, which would decrease the amount of heat reaching the bulkheads. The simulated thermally induced pore pressure increase in the clay bulkhead reasonably matched the measured data for the saturated portion. The difference in magnitude between simulated and measured rock pore pressures indicates that thermo hy draulic simulation should be coupled with a mechanical component when the stiffness of the media is large and hydraulic conductivity is low.Key words: numerical modelling, Tunnel Sealing Experiment, nuclear waste management, hydraulic head, thermal conduction, thermal convection.
Resistance factors for settlement design
Authors: Fenton Gordon A , Griffiths D V , Cavers W
Published: October 2005

To control serviceability problems arising from excessive settlement of shallow footings, geotechnical design codes generally include specifications regarding maximum settlement, which often govern the footing design. Once the footing has been designed and constructed, the actual settlement it experiences on a real three-dimensional soil mass can be quite different than expected, due to the soil's spatial variability. Because of this generally large variability (compared to other engineering materials, such as concrete and steel) and because this particular serviceability limit state often governs the design, it makes sense to consider a reliability-based approach to settlement design. This paper looks in some detail at a load and resistance factor design (LRFD) approach to limiting footing settlement. In particular, the resistance factors required to achieve a certain level of settlement reliability as a function of soil variability and site investigation intensity are determined analytically using random field theory. Simplified approximate relationships are proposed and tested using simulation via the random finite element method. It is found that the simplified relationships are validated both by theory and simulation and so can be used to augment the calibration of geotechnical LRFD code provisions with respect to shallow foundation settlement. Key words: reliability-based design, settlement, geotechnical, shallow foundation, random field, probability.
Effect of geosynthetics on the hydraulic performance of leak-detection systems
Authors: Rowe R Kerry , Iryo T
Published: October 2005

The hydraulic performance of a leak-detection  secondary leachate collection system below a composite liner consisting of a geomembrane (GM) over a geosynthetic clay liner (GCL) is studied using the finite element method. The effect of the initial conditions in the underlying foundation layer (e.g., compacted site soils), distance from the leakage point to the drainage point, properties of the GCL, hydration history of the GCL, and the presenceabsence of a foundation layer are examined. The interaction between the GMGCL interface, GCL foundation layer interface, and the underlying geocomposite is investigated. The time for leakage to be detected is shown to be highly dependent on the material below the composite liner, the initial degree of saturation of the material, and the distance between the hole wrinkle and the drainage point in the system. Under some circumstances this could result in leakage not being detected for a considerable period of time. Predicted leakage is shown to be similar in magnitude to that reported in field monitoring. A comparison of an analytical solution for steady state conditions with the numerical solution shows excellent agreement.Key words: geomembranes, geosynthetic clay liners, leakage, leachate collection, finite element method.
An experimental study of the interaction of vertically loaded pile groups in sand
Authors: Lee Su-Hyung , Chung Choong-Ki
Published: October 2005

The interactions among closely located piles and a cap in a pile group are complex. The current design practice for vertically loaded pile groups roughly estimates their overall behavior and generally yields conservative estimations of the group capacity. For a proper pile group design, factors such as the interaction among piles, the interaction between cap and piles, and the influence of pile installation method all need to be considered. This paper presents the results of the model test, which can be used to better understand the interactions of vertically loaded pile groups in granular soil. Load tests were carried out on the following: an isolated single pile, single-loaded center piles in groups, a footing without any piling, free standing pile groups, and piled footings. The influences of pile driving and the interactions among bearing components on loadsettlement and load transfer characteristics of piles and on the bearing behavior of a cap in a group are investigated separately by comparing their respective test results. The favorable interaction effects that increase pile capacities are identified.Key words: pile group, pile installation, interaction, model test, free standing, piled footing.
Synthesis and preliminary bioactivity evaluation of new pregnane brassinosteroid-like compounds
Authors: Rivera Daniel G , Coll Francisco
Published: October 2005

Seven new pregnane compounds bearing some representative A- and B-ring brassinosteroid functions, as well as hydrogen bond donor and acceptor ones on the D ring, were efficiently synthesized. The obtained compounds did not show remarkable plant growth-promoting activity in the radish hypocotyl elongation and cotyledon expansion bioassays, however, introducing oxygen and amino functions on the D ring led to an enhancement of the bioactivity. The 16β-functionalized pregnane brassinosteroid-like compounds were slightly more active than the 16α-functionalized ones.Key words: steroids, brassinosteroids, pregnane analogues.
Late metal salicylaldimine complexes derived from 5-aminosalicylic acid  Molecular structure of a zwitterionic mono Schiff base zinc complex
Authors: Bourque Tara A , Nelles Megan E , Gullon Teri J , Garon Christian N , Ringer Melissa K , Leger Lisa J , Mason Jamie W , Wheaton Susan L , Baerlocher Felix J , Vogels Christopher M , Decken Andreas , Westcott Stephen A
Published: October 2005

Condensation of salicylaldehyde (2-HOC6H4C(O)H) with 5-aminosalicylic acid (5-H2NC6H3-2-(OH)-CO2H) afforded the Schiff base 2-HOC6H4C(H)=NC6H3-2-(OH)-5-CO2H (a). Similar reactivity with 5-bromosalicylaldehyde was also observed to give 5-Br-2-HOC6H3C(H)=NC6H3-2-(OH)-5-CO2H (b). Reaction of these salicylaldehydes with Pd(II), Cu(II), and Zn(II) salts gave the corresponding bis(N-arylsalicylaldiminato)metal complexes (M = Pd (1), Cu (2), Zn (3)). The molecular structure of the Schiff base compound a has been confirmed by an X-ray diffraction study. Crystals of a were monoclinic, space group P2(1)/c, a = 7.0164(7) Å, b = 11.0088(11) Å, c = 14.8980(15) Å, β = 102.917(2)°, Z = 4. The molecular structure of a novel zwitterionic conformer of 3a was also characterized by an X-ray diffraction study. Crystals of 4 were monoclinic, space group P2(1)/c, a = 9.5284(5) Å, b = 19.5335(11) Å, c = 8.6508(5) Å, β = 90.596(1)°, Z = 4. All new compounds have been tested for their antifungal activity against Aspergillus niger and Aspergillus flavus. Key words: 5-aminosalicylic acid (5-ASA), antifungal, copper, palladium, salicylaldimines, Schiff base, zinc.
2003 Alcan Award Lecture  Roles of the adjacent metals in the coupling of methylene groups promoted by heterobinuclear complexes of Group 8 and 9 metals
Authors: Cowie Martin
Published: October 2005

The reactivities of the heterobinuclear complexes, [MM′(CO)4(dppm)2][X] (MM′ = RhOs, RhRu, IrRu; dppm =

µ-Ph2PCH2PPh2; X = BF4, CF3SO3) with diazomethane are reported. The RhOs species reacts to give three products of methylene-group incorporation, depending on the temperature; at 80 °C the methylene bridged product, [RhOs(CO)4(µ-CH2)(dppm)2][X], is formed exclusively, at ambient temperature only [RhOs(η1-C3H5)(CH3)(CO)3(dppm)2][X], having the allyl group bound to Rh and the methyl group bound to Os, is obtained, while at intermediate temperatures [RhOs(η1:η1-C4H8)(CO)3(dppm)2][X], having the butanediyl fragment chelating on Os, is generated. Based on labeling studies a mechanism is proposed rationalizing formation of the different products. Under the same range of conditions the Rh/Ru and Ir/Ru species yield only the methylene bridged products, [MM′(CO)4(µ-CH2)(dppm)2][X] (MM′ = RhRu, IrRu). A rationalization for the different reactivities observed and a description of the roles of the different metals in coupling of the methylene groups are presented. Attempts to model key intermediates in the methylene coupling sequence promoted by the Rh/Os complexes, through coupling of methylene groups with ethylene or alkynes, are described. Key words: heterobinuclear, rhodium/osmium, rhodium/ruthenium, iridium/ruthenium, methylene coupling, FischerTropsch, alkyne insertions, bimetallic cooperativity.
Salicylaldimine dimers derived from 2-H2NC6H4Bpin (pin = 1,2-O2C2Me4)
Authors: Webb Jonathan D , Darwish Hanni A , Zhang Haiwen , Wheaton Susan L , Baerlocher Felix J , Vogels Christopher M , Decken Andreas , Westcott Stephen A
Published: October 2005

Condensation of salicylaldehyde (2-HOC6H4C(O)H) with 2-H2NC6H4Bpin (pin = 1,2-O2C2Me4) afforded the macrocyclic dimer 1 with an OBOBO structural unit. Similar reactivity with substituted salicylaldehyde derivatives gave the corresponding Schiff bases 26. Crystals of 1 were triclinic, space group P-1, a = 9.7915(4) Å, b = 10.8569(5) Å, c = 12.8445(6) Å, α = 102.067(1)°, β = 96.011(1)°, γ = 90.458(1)°, Z = 2. All new compounds have been tested for their antifungal activity against Aspergillus niger and Aspergillus flavus.Key words: antifungal, boron, dehydration, heterocycles, Schiff bases.
Role of the solvent in the oxidative process of a Hg electrode in the presence of thiopyrimidine derivatives
Authors: Bakari Souad , Borsari Marco , Cannio Maria , Gavioli Giovanna , Ranieri Antonio , Peressini Silvia , Tavagnacco Claudio
Published: October 2005

The electrochemical oxidation of a Hg electrode in the presence of thiopyrimidine derivatives has been investigated in a collection of organic solvents using voltammetric and polarographic techniques. Remarkable adsorption phenomena control the electrochemical process, which in all cases gives rise to a Hg(I) complex. The Laviron adsorption model is found to describe well the polarographic adsorption wave. Some correlations between adsorption parameters and solvent properties have also been observed and discussed.Key words: polarography, voltammetry, thiopyrimidine, solvent effect, adsorption.
Study of the nitration of di-n-octylcrown-6 calix[4]arene using LCMS, NMR, and molecular modelling
Authors: Jankowski C K , Van Calsteren M- R , Aychet N , Dozol J F , Moulin C , Lamouroux C
Published: October 2005

The selective HNO3 nitration of di-n-octylcrown-6 calix[4]arene using different conditions, studied with LCMS and NMR (1H and 13C) spectroscopic techniques, lead to the identification of most of the expected nitro derivative isomeric compounds. The formation of these isomers under acidic and radiolytic conditions is discussed with the help of molecular modelling.Key words: calix crown compounds, nitration of calixarenes, NMR of isomeric nitrocalixarenes, LC-ESI-MS.
Triazene derivatives of (1,x)-diazacycloalkanes. Part IV.1 Synthesis and characterization of 1-[2-aryl-1-diazenyl]-3-(3-[2-aryl-1-diazenyl]hexahydro-1-pyrimidinylmethyl)hexahydropyrimidines and 1-(5,5-dimethyl-3-[2-aryl-1-diazenyl]hexahydro-1-pyrimidinylmethyl)-5,5-dimethyl-3-[2-aryl-1-diazenyl]hexahydropyrimidines from the reaction of diazonium salts with mixtures of formaldehyde and 1,3-diaminopropanes
Authors: Moser Shasta , Church Ryan , Peori M Brad , Vaughan Keith
Published: October 2005

Two new series of bistriazenes have been synthesized from a general reaction of diazonium salts with a mixture of a propanediamine and formaldehyde. Such reaction with 1,3-diaminopropane itself affords the 1-[2-aryl-1-diazenyl]-3-(3-[2-aryl-1-diazenyl]hexahydro-1-pyrimidinylmethyl)hexahydropyrimidines (6). 2,2-Dimethyl-1,3-diamino propane reacts in an analogous manner to give the 1-(5,5-dimethyl-3-[2-aryl-1-diazenyl]hexahydro-1-pyrimidinylmethyl)- 5,5-dimethyl-3-[2-aryl-1-diazenyl]hexahydropyrimidines (7). All new compounds have been characterized by IR and NMR spectroscopy, with elemental analysis or high resolution mass spectrometry of most of the new compounds. NMR assignments have been analyzed by a series of DEPT, COSY, and HSQC experiments. One example of each series has been unequivocally characterized by X-ray crystallography. The general conclusion of this study is that alkanediamines with three carbon atoms in the spacer link between the nitrogen atoms give rise to the linear bicyclic molecules of type 18, in contrast to the case of ethylenediamine (spacer link has two carbon atoms), which affords cage-like molecules of type 17.Key words: bistriazene, hexahydropyrimidine, diazonium coupling, formaldehyde, diaminopropane, nuclear magnetic resonance.
Electron spin resonance analysis of the oxidation reactions of nitrone type spin traps with gold(III) ion
Authors: Nakajima Akira , Ueda Yuto , Endoh Nobuyuki , Tajima Kunihiko , Makino Keisuke
Published: October 2005

When cyclic nitrones, such as 5,5-dimethyl-1-pyrroline-N-oxide (DMPO), 4-phenyl-5,5-dimethyl-1- pyrroline-N-oxide (PDMPO), and 3,3,5,5-tetramethyl-1-pyrroline-N-oxide (M4PO) were mixed with hydrogen tetrachloro aurate(III), DMPOX (5,5-dimethyl-1-pyrrolid-2-one-N-oxyl) type free radicals appeared with the precipitation of Au(0). The reaction did not proceed with noncyclic nitrones, such as N-tert-butyl-α-phenyl-nitrone (PBN) and α-(4-pyridyl-1-oxide)-N-tert-butyl-nitrone (POBN). The order of the HAuCl4 decrease was DMPO > PDMPO > M4PO. The reaction was depressed by the addition of chloride or hydroxide ions. 1-Hydroxy-5,5-dimethyl-1-pyrrolid-2-one (HDMPN), the precursor of DMPOX, was also oxidized to DMPOX by HAuCl4. Every step of the gold reduction from Au(III) to Au(0) can be used for the oxidation of HDMPN to DMPOX. Based on these and previous results, the reaction was assumed to proceed by the following scheme consisting of a ligand exchange interaction of AuCl4 with >N+O in DMPO, then nucleophilic addition of a water molecule to DMPO, then the stepwise intramolecular transfer of three electrons from DMPO to Au(III), and finally the precipitation of Au(0). Key words: ESR, nitrone, spin traps, DMPO, DMPOX, gold(III) ion.
Calmodulin antagonists: Structure of N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride (W-7) and comparison with trifluoperazine (TFP)  Calmodulin binding
Authors: Hempel Andrew , Camerman Norman , Mastropaolo Donald , Camerman Arthur
Published: October 2005

The crystal structure of the title compound contains one N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride molecule in the asymmetric unit. The molecule adopts an extended conformation with a linear hexyl group. Protonation occurs at the side chain terminal nitrogen atom. Hydrophobic packing and a three-dimensional hydrogen-bond network, involving all the hydrogen atoms capable of making hydrogen-bond contacts, stabilizes the crystal structure. Due to head-to-head and tail-to-tail arrangement of these hydrophobic molecules, an unusually long cell constant (b = 61.27 Å) characterizes the crystal structure. A stereochemical comparison with trifluoperazine suggests similar calmodulin binding mechanisms.Key words: crystal structure, stereochemistry, W-7, calmodulin binding, TFP.
A mild and efficient procedure for the conversion of aromatic carboxylic esters to secondary amides
Authors: Arora Revika , Paul Satya , Gupta Rajive
Published: October 2005

A mild and efficient procedure has been developed for the conversion of aromatic carboxylic esters to secondary amides using reusable Zn dust with microwave heating in the presence of N,N-dimethylformamide or conventional heating by stirring in an oil bath using THF as solvent. Zn dust can be reused several times after simple washing with dil. HCl and distilled water.Key words: aromatic carboxylic esters, aromatic primary amines, secondary amides, Zn dust, microwave activation.
Catalyzed β scission of a carbenium ion  Mechanistic differences from varying catalyst basicity
Authors: Li Qingbin , East Allan LL
Published: October 2005

The β-scission mechanism of physisorbed and chemisorbed pentenium ions, as catalyzed by AlH2(OH)2 and by AlHCl3 anions, was investigated using density functional theory computations and explicit-contact modelling. A thorough search of intermediates was performed for each catalyst. On the aluminum chloride, β scission of an aliphatic, secondary carbenium ion featured chemisorbed and physisorbed ion intermediates, while on the aluminum hydroxide, β scission featured chemisorbed ions but physisorbed neutral species. The importance of this work is its demonstration of a qualitatively different mechanism, with qualitatively different intermediates, due only to the different basicity of the two catalysts.Key words: CC bond fission, β scission, carbenium ion, catalysis, mechanism.
Advanced regeneration and seedling establishment in small cutblocks in high-elevation sprucefir forest at Sicamous Creek, southern British Columbia
Authors: Parish Roberta , Antos Joseph A
Published: October 2005

We examined the potential of natural regeneration for stocking 1-ha patch cuts in high-elevation Engelmann spruce (Picea engelmannii Parry)  subalpine fir (Abies lasiocarpa (Hook.) Nutt.) forests. Using the Sicamous Creek Silvicultural Systems site, which was harvested during winter 19941995, we established 1-m2 plots in patch cuts, forest edge, and untreated control forest. We marked and recorded microsite characteristics for all advanced regeneration and new recruits for up to 5 years; over 12 000 individuals were included. Advanced regeneration was abundant and was about one-quarter spruce. Spruce and fir germinants occurred in all years, but numbers varied greatly, with a very large cohort in 1998. Both advanced regeneration and new recruits were concentrated on decaying logs. Mortality of advanced regeneration was high in the patch cuts following harvest, but subsequent survival was good, approaching rates in the untreated forest within 4 years. Survival rates were higher for spruce than fir, but differed little among surface types and microtopographic positions. Survival of new recruits was high, approximately 50% the first year and 70% during the second, and was similar between spruce and fir. If the 1998 cohort has similar survival, the patch cuts could be adequately stocked. Use of natural regeneration, in combination with infill planting, is a viable option for stocking small openings in wet high-elevation forests in southern British Columbia.
Canopy gap disturbance and succession in trembling aspen dominated boreal forests in northeastern Ontario
Authors: Hill Steven B , Mallik Azim U , Chen Han YH
Published: October 2005

Canopy gaps play an important role in forest vegetation dynamics when fire return intervals are long. However, there is little known about the role of gaps in the development of forest stands that initially dominate following stand-replacing disturbance. We investigated gap disturbance during the breakup of trembling aspen (Populus tremuloides Michx.) stands at two scales: at the stand level we quantified gap fraction and gap size as stand development proceeds; at the gap level we determined causes of gap-maker mortality and evaluated resulting gap-maker structure and decay as stand development proceeds. We also evaluated the impact that gaps have on stand transition by quantifying the abundance and growth of juvenile trees in gaps of different sizes and ages. Ten stands between 60 and 120 years since fire in northeastern Ontario were sampled using line intersect transects. Gap fraction doubled (∼18%36%) and mean gap size was more than four times greater (∼45200 m2) over the time period. Standing dead gap makers in early states of decay were most frequent in young stands, whereas snapped gap makers in various states of decay were most frequent in old stands. Infection by fungal pathogens was the most frequent cause of mortality (56%) and was not related to time since fire. Balsam fir (Abies balsamea (L.) Mill.) was the most abundant juvenile recruit. However, transition probabilities for tree species were independent of gap type. These results indicate that gap creation is frequent during early stages of stand development in boreal forests; however, it is unlikely that successional trajectory is affected by their formation.
Soil microclimate and nitrogen availability 10 years after mechanical site preparation in northern British Columbia
Authors: MacKenzie M D , Schmidt M G , Bedford L
Published: October 2005

Mechanical site preparation (MSP) changes the distribution and character of forest floor and mineral soil and may affect soil nutrient availability, soil water content, and soil temperature. The effects of different kinds of MSP were compared to a control in the tenth growing season at two research sites in northern British Columbia. To compare MSP results with those of the natural disturbance regime, a burned windrow treatment was also included in the analysis. The bedding plow, fire, and madge treatments all had significantly greater crop-tree growth compared to the control. The bedding plow and madge treatments had significantly lower soil bulk density, higher soil temperature, and lower soil water throughout the growing season compared with that of the control. The bedding plow also resulted in significantly higher concentrations of total carbon, total nitrogen, NH4+, and NO3than that of the control, at both the 010 and 1020 cm depths. The madge rotoclear resulted in significantly greater potential mineralizable N than that of the control. Ionic resins bags, installed for one growing season, did not show any significant treatment differences in available soil nitrogen. MSP did not reduce soil fertility on these sites when compared with an untreated control, but it is difficult to say that it improved it.
Tree growth, foliar chemistry, and nitrogen cycling across a nitrogen deposition gradient in southern Appalachian deciduous forests
Authors: Boggs Johnny L , McNulty Steven G , Gavazzi Michael J , Myers Jennifer Moore
Published: October 2005

The declining health of high-elevation red spruce (Picea rubens Sarg.) and Fraser fir (Abies fraseri (Pursh) Poir.) in the southern Appalachian region has long been linked to nitrogen (N) deposition. Recently, N deposition has also been proposed as a source of negative health impacts in lower elevation deciduous forests. In 1998 we established 46 plots on six sites in North Carolina and Virginia dominated by American beech (Fagus grandifolia Ehrh.), sugar maple (Acer saccharum Marsh.), and yellow birch (Betula alleghaniensis Britt). We evaluated several response variables across an N deposition gradient, including annual basal area growth; foliage percent N, Al, P, K, Mg, and Ca; and forest floor percent N, Mg, and C, pH, and potential net nitrification and N mineralization rates. We found a significant linear relationship between N deposition and basal area growth in sugar maple, but not in American beech or yellow birch. In addition, we found a significant relationship between N deposition and foliar chemistry (foliar %N in all species, foliar Mg/N and %K in sugar maple, and %P in sugar maple and yellow birch). Foliar %N of the three studied species was high relative to values reported in other studies in the United States and Canada. Several forest floor response variables (%N, C/N, pH, Mg/N, and potential net nitrification and N mineralization rates and nitrification/mineralization fractions) were also correlated with N deposition. The correlations between the above response variables and N deposition are consistent with the influence of chronic N deposition on forested ecosystems measured in other regions and suggest that chronic N deposition may be influencing forest structure and chemistry within the southern region.
Modeling early forest succession following clear-cutting in western Oregon
Authors: Yang Zhiqiang , Cohen Warren B , Harmon Mark E
Published: October 2005

In the Pacific Northwest, the process of conifer development after stand-replacing disturbance has important implications for many forest processes (e.g., carbon storage, nutrient cycling, and biodiversity). This paper examines conifer development in the Coast Range Province and Western Cascades Province of Oregon using repeat interpretation of historic aerial photographs from 1959 to 1997 to examine the canopy cover change of different life forms: shrubs, hardwood trees, and conifer trees. Ninety-four stands from the Western Cascades Province and 59 stands from the Coast Range Province were photointerpreted in roughly 5-year intervals. A ChapmanRichards growth function was used to model conifer cover development for all sample stands. Based on the photo data and the ChapmanRichards function, these stands were classified into one of seven early forest successional trajectories defined by the vegetation physiognomy. Succession in the Coast Range Province and Western Cascades Province were compared using parameters derived from the ChapmanRichards growth function. Our results echo previous studies in that rates and densities of conifer regeneration varied markedly among sites; however, our results also indicate that early forest succession differs in the two study regions in terms of both trajectories and rates. Conifer regeneration in the Western Cascades Province tends to have longer delays in establishing and slower rates compared with the Coast Range Province.
Aspen plant community response to organic matter removal and soil compaction
Authors: Haeussler Sybille , Kabzems Richard
Published: October 2005

Organic matter removal and reduced soil aeration porosity during logging are important factors influencing the sustained productivity of managed forest ecosystems. We studied the 4-year effect of these factors on diversity and composition of a trembling aspen (Populus tremuloides Michx.) plant community in northeastern British Columbia, Canada, in a completely randomized experiment with three levels of organic matter removal (tree stems; stems and slash; stems, slash, and forest floor) and three levels of soil compaction (none; intermediate (2-cm impression); heavy (5-cm impression)). Tree stem removal caused the greatest change in species diversity (30% of variance; ANOVA p ≤ 0.01), increasing the dominance of aspen and Calamagrostis canadensis (Michx.) Beauv. over other species. Slash removal had little effect. Forest floor removal caused the greatest compositional change (37% of variance; MANOVA p = 0.001), favoring ruderal over bud-banking species. Presence or absence of forest floor better explained these changes than any soil physical or chemical parameter. Although dominance of aspen over Calamagrostis was positively correlated with soil aeration porosity (R2 = 0.50, n = 27, p < 0.001), there were few differences between intermediate and heavy compaction. In this ecosystem, disturbances that reduce forest floor thickness without compacting soils will likely optimize plant species diversity and enhance aspen regrowth.
PAIRS-PRODUCTION OF HIGGS IN ASSOCIATION WITH BOTTOM QUARKS PAIRS AT e+e- COLLIDERS
Authors: GUTIÉRREZ-RODRÍGUEZ A. , HERNÁNDEZ-RUÍZ M. A. , SAMPAYO O. A.
Published: October 2005

In a previous paper, we studied the Higgs pair production in the standard model with the reaction [Formula: see text]. Based on this, we study the Higgs pair production via [Formula: see text]. We evaluate the total cross-section of [Formula: see text] and calculate the total number of events considering the complete set of Feynman diagrams at tree-level, and compare this process with the process [Formula: see text]. The numerical computation is done for the energy which is expected to be available at a possible Next Linear e+e- Collider with a center-of-mass energy 800, 1000, 1600 GeV and luminosity 1000 fb-1.
MOMENTUM AND DENSITY DEPENDENCE OF ISOVECTOR PART OF NUCLEAR MEAN FIELD
Authors: BEHERA BASUDEB , ROUTRAY TUSHAR RANJAN , PRADHAN ALIVA
Published: October 2005

Momentum and density dependence of the isovector part of nuclear mean field uτ(k, ρ) is studied by using effective interactions having general form. It is found that only the difference between finite range parts of the exchange interactions between like and unlike nucleons accounts for the momentum dependence of uτ(k, ρ). Depending on the choice of the parameters of these exchange interactions, two conflicting trends of momentum dependence of uτ(k, ρ) are noted which lead to two opposite types of splitting of neutron and proton effective masses. The behavior of uτ(k, ρ) at the Fermi momentum k=k F is related to the density dependence of nuclear symmetry energy Jτ(ρ) and effective nucleon mass M*(k=k F , ρ)/M in symmetric nuclear matter. The need for possible theoretical and experimental efforts to constrain the high density behavior of Jτ(ρ) as well as to resolve the puzzle regarding the two opposite types of splitting of neutron and proton effective masses are also stressed.
SEARCH FOR POSSIBLE WAY OF PRODUCING SUPER-HEAVY ELEMENTS: DYNAMIC STUDY ON DAMPED REACTIONS OF 244Pu+244Pu, 238U+238U and 197Au+197Au
Authors: WANG NING , LI ZHUXIA , WU XIZHEN , ZHAO ENGUANG
Published: October 2005

By using the Improved Quantum Molecular Dynamics model, the 244 Pu +244 Pu , 238 U +238 U and 197 Au +197 Au reactions at the energy range of E c.m. =800 MeV to 2000 MeV are studied. We find that the production probability of superheavy fragments (SHFs) with Z≥114 for the 244 Pu +244 Pu reaction is much higher compared with that for the 238 U +238 U reaction and no product of SHF is found for the 197 Au +197 Au . The production probability of SHFs strongly depends on the incident energy and a narrowly peaked energy dependence of production probability is found. The decay mechanism of the composite system of projectile and target is studied and the time scale of decay process is explored. The binding energies and the shapes of SHFs are studied. The binding energies of SHFs are broadly distributed and the shapes of SHFs are strongly deformed.
CHARGED ROTATING BLACK HOLE FORMATION FROM THIN SHELL COLLAPSE IN THREE DIMENSIONS
Authors: OLEA RODRIGO
Published: October 2005

The thin shell collapse leading to the formation of charged rotating black holes in three dimensions is analyzed in the light of a recently developed Hamiltonian formalism for these systems. It is proposed to demand, as a way to reconcile the properties of an infinitely extended solenoid in flat space with a magnetic black hole in three dimensions, that the magnetic field should vanish just outside the shell. The adoption of this boundary condition results in an exterior solution with a magnetic field different from zero at a finite distance from the shell. The interior solution is also found and assigns another interpretation, in a different context, to the magnetic solution previously obtained by Clément and Hirschmann and Welch.
TETRAHEDRAL FAMILY SYMMETRY AND THE NEUTRINO MIXING MATRIX
Authors: MA ERNEST
Published: October 2005

In a new application of the discrete non-Abelian symmetry A4 using the canonical seesaw mechanism, a three-parameter form of the neutrino mass matrix is derived. It predicts the following mixing angles for neutrino oscillations: θ13=0, sin 2θ23=1/2, and sin 2θ12 close, but not exactly equal to 1/3, in one natural symmetry limit.
YANG–MILLS, COMPLEX STRUCTURES AND CHERN'S LAST THEOREM
Authors: MARSHAKOV ANDREI , NIEMI ANTTI J.
Published: October 2005

Recently Shiing-Shen Chern suggested that the six-dimensional sphere 𝕊6 has no complex structure. Here we explore the relations between his arguments and Yang–Mills theories. In particular, we propose that Chern's approach is widely applicable to investigate connections between the geometry of manifolds and the structure of gauge theories. We also discuss several examples of manifolds, both with and without a complex structure.
ON THE INTERACTION BETWEEN THERMALIZED NEUTRINOS AND COSMOLOGICAL GRAVITATIONAL WAVES ABOVE THE ELECTROWEAK UNIFICATION SCALE
Authors: LATTANZI MASSIMILIANO , MONTANI GIOVANNI
Published: October 2005

We investigate the interaction between the cosmological relic neutrinos, and primordial gravitational waves entering the horizon before the electroweak phase transition, corresponding to observable frequencies today ν0≳10-5 Hz . We give an analytic formula for the traceless transverse part of the anisotropic stress tensor, due to weakly interacting neutrinos, and derive an integro-differential equation describing the propagation of cosmological gravitational waves at these conditions. We find that this leads to a decrease of the wave intensity in the frequency region accessible to the LISA space interferometer, that is at the present the most promising way to obtain a direct detection of a cosmological gravitational wave. The absorbed intensity does not depend neither on the perturbation wavelength, nor on the details of neutrino interactions, and is affected only by the neutrino fraction fν. The transmitted intensity amounts to 88% for the standard value fν=0.40523. An approximate formula for non-standard values of fν is given.
QUANTIZATION OF NEVEU–SCHWARZ–RAMOND SUPERSTRING MODEL IN (10+2)-DIMENSIONAL SPACE–TIME
Authors: TSUKIOKA TAKUYA , WATABIKI YOSHIYUKI
Published: October 2005

We construct a Neveu–Schwarz–Ramond superstring model which is invariant under supersymmetric U (1)V× U (1)Agauge transformations as well as the supergeneral coordinate, the superlocal Lorentz and the super-Weyl transformations on the string worldsheet. We quantize the superstring model by covariant BRST formulation á la Batalin and Vilkovisky and noncovariant lightcone gauge formulation. Upon the quantizations the model turns out to be formulated consistently in (10+2)-dimensional background space–time involving two time dimensions.
CUBIC SUPERSYMMETRY AND ABELIAN GAUGE INVARIANCE
Authors: MOULTAKA G. , RAUSCH DE TRAUBENBERG M. , TANASĂ A.
Published: October 2005

On the basis of recent results extending nontrivially the Poincaré symmetry, we investigate the properties of bosonic multiplets including 2-form gauge fields. Invariant-free Lagrangians are explicitly built which involve possibly 3- and 4-form fields. We also study in detail the interplay between this symmetry and a U (1) gauge symmetry, and in particular the implications of the automatic gauge-fixing of the latter corresponding to a residual gauge invariance, as well as the absence of self-interaction terms.
SCALE TRANSFORMATIONS ON THE NONCOMMUTATIVE PLANE AND THE SEIBERG–WITTEN MAP
Authors: PINZUL A. , STERN A.
Published: October 2005

We write down three kinds of scale transformations (i)–(iii) on the noncommutative plane. Transformation (i) is the analogue of standard dilations on the plane, transformation (ii) is a rescaling of the noncommutative parameter θ, and transformation (iii) is a combination of the previous two, whereby the defining relations for the noncommutative plane are preserved. The action of the three transformations is defined on gauge fields evaluated at fixed coordinates and θ. The transformations are obtained only up to terms which transform covariantly under gauge transformations. We give possible constraints on these terms. We show how the transformations (i) and (ii) depend on the choice of star product, and show the relation of (ii) to Seiberg–Witten transformations. Because transformation (iii) preserves the fundamental commutation relations it is a symmetry of the algebra. One has the possibility of implementing it as a symmetry of the dynamics, as well, in noncommutative field theories where θ is not fixed.
ON TETRAQUARK MESON STATES
Authors: GUPTA VIRENDRA
Published: October 2005

It is suggested that the narrow meson state seen in the the SELEX experiment is a [Formula: see text] tetraquark state. Characteristics of other possible tetraquarks formed out of c and s quarks and antiquarks are considered.
TRANSLATIONAL ENTANGLEMENT AND TELEPORTATION OF MATTER WAVEPACKETS BY COLLISIONS AND HALF-COLLISIONS
Authors: FISCH L. , TAL A. , KURIZKI G.
Published: October 2005

To date, the translationally-entangled state originally proposed by Einstein, Podolsky and Rosen (EPR) in 1935 has not been experimentally realized for massive particles. Opatrný and Kurizki [Phys. Rev. Lett.86, 3180 (2000)] have suggested the creation of a position- and momentum-correlated, i.e., translationally-entangled, pair of particles approximating the EPR state by dissociation of cold diatomic molecules, and further manipulation of the EPR pair effecting matter-wave teleportation. Here we aim at setting the principles of and quantifying translational entanglement by collisions and half-collisions. In collisions, the resonance width s and the initial phase-space distributions are shown to determine the degree of post-collisional momentum entanglement. Half-collisions (dissociation) are shown to yield different types of approximate EPR states. We analyse a feasible realization of translational EPR entanglement and teleportation via cold-molecule Raman dissociation and subsequent collisions, resolving both practical and conceptual difficulties it has faced so far: How to avoid entanglement loss due to the wavepacket spreading of the dissociation fragments? How to measure both position and momentum correlations of the dissociation fragments with sufficient accuracy to verify their EPR correlations? How to reliably perform two-particle (Bell) position and momentum measurements on one of the fragments and the wavepacket to be teleported?
L-2 DEGREE REDUCTION OF TRIANGULAR BÉZIER SURFACES WITH COMMON TANGENT PLANES AT VERTICES
Authors: RABABAH ABEDALLAH
Published: October 2005

In this paper, we present a method of degree reduction for triangular Bézier surfaces. The approximate and the original triangular Bézier surfaces have common tangent planes at the vertices. We use the least squares method with the L 2 and l2 norms to get a closed form for the reduction of the degree and show that both solutions are the same. This scheme uses the matrix representations of the degree raising and the Bézier control vertices. The computational cost of the method is evaluated. The error term is derived and a numerical example is given.
JOINT SEPARATION OF GEOMETRIC CLUSTERS AND THE EXTREME IRREGULARITIES OF REGULAR POLYHEDRA
Authors: GUHA SUMANTA
Published: October 2005

We propose a natural scheme to measure the joint separation of a cluster of objects in general geometric settings. In particular, here the measure is developed for finite sets of planes in ℝ3 in terms of extreme configurations of vectors on the planes of a given set. We prove geometric and graph-theoretic results about extreme configurations on arbitrary finite plane sets. We then specialize to the planes bounding a regular polyhedron in order to exploit the symmetries. However, even then results are non-trivial and surprising – extreme configurations on regular polyhedra may turn out to be highly irregular.
A LOWER BOUND FOR LEBESGUE'S UNIVERSAL COVER PROBLEM
Authors: BRASS PETER , SHARIFI MEHRBOD
Published: October 2005

In the following we show that any convex set that contains a congruent copy of any set of diameter one (universal cover) has area at least 0.832. This considerably improves the lower bound for Lebesgue's universal cover problem, using a combination of computer search and geometric bounds.
PRODUCT-BASED CAUSAL NETWORKS AND QUANTITATIVE POSSIBILISTIC BASES
Authors: BENFERHAT SALEM , KHELLAF FAIZA HANED , MOKHTARI AICHA
Published: October 2005

In possibility theory, there are two kinds of possibilistic causal networks depending if possibilistic conditioning is based on the minimum or on the product operator. Similarly there are also two kinds of possibilistic logic: standard (min-based) possibilistic logic and quantitative (product-based) possibilistic logic. Recently, several equivalent transformations between standard possibilistic logic and min-based causal networks have been proposed. This paper goes one step further and shows that product-based causal networks can be encoded into product-based knowledge bases. The converse transformation is also provided.
DECISION ANALYSIS WITH MULTIPLE OBJECTIVES IN A FRAMEWORK FOR EVALUATING IMPRECISION
Authors: LARSSON ARON , JOHANSSON JIM , EKENBERG LOVE , DANIELSON MATS
Published: October 2005

We present a decision tree evaluation method for analyzing multi-attribute decisions under risk, where information is numerically imprecise. The approach extends the use of additive and multiplicative utility functions for supporting evaluation of imprecise statements, relaxing requirements for precise estimates of decision parameters. Information is modeled in convex sets of utility and probability measures restricted by closed intervals. Evaluation is done relative to a set of rules, generalizing the concept of admissibility, computationally handled through optimization of aggregated utility functions. Pros and cons of two approaches, and tradeoffs in selecting a utility function, are discussed.
INTERVAL METHODS IN KNOWLEDGE REPRESENTATION
Authors: KREINOVICH VLADIK
Published: October 2005

This section is maintained by Vladik Kreinovich. Please send your abstracts (or copies of papers that you want to see reviewed here) to vladik@utep.edu, or by regular mail to: Vladik Kreinovich, Department of Computer Science, University of Texas at El Paso, El Paso, TX 79968, USA.
Leptin receptor-deficient obese Zucker rats reduce their food intake in response to hypobaric hypoxia
Authors: Simler Nadine , Grosfeld Alexandra , Peinnequin André , Guerre-Millo Michèle , Bigard André-Xavier
Published: October 2005

Exposure to hypoxia induces anorexia in humans and rodents, but the role of leptin remains under discussion and that of orexigenic and anorexigenic hypothalamic neuropeptides remains unknown. The present study was designed to address this issue by using obese (Leprfa/Leprfa) Zucker rats, a rat model of genetic leptin receptor deficiency. Homozygous lean (LeprFA/LeprFA) and obese (Leprfa/Leprfa) rats were randomly assigned to two groups, either kept at ambient pressure or exposed to hypobaric hypoxia for 1, 2, or 4 days (barometric pressure, 505 hPa). Food intake and body weight were recorded throughout the experiment. The expression of leptin and vascular endothelial growth factor (VEGF) genes was studied in adipose tissue with real-time quantitative PCR and that of selected orexigenic and anorexigenic neuropeptides was measured in the hypothalamus. Lean and obese rats exhibited a similar hypophagia (38 and 67% of initial values at day 1, respectively, P < 0.01) and initial decrease in body weight during hypoxia exposure. Hypoxia led to increased plasma leptin levels only in obese rats. This resulted from increased leptin gene expression in adipose tissue in response to hypoxia, in association with enhanced VEGF gene expression. Increased hypothalamic neuropeptide Y levels in lean rats 2 days after hypoxia exposure contributed to accounting for the enhanced food consumption. No significant changes occurred in the expression of other hypothalamic neuropeptides involved in the control of food intake. This study demonstrates unequivocally that altitude-induced anorexia cannot be ascribed to anorectic signals triggered by enhanced leptin production or alterations of hypothalamic neuropeptides involved in anabolic or catabolic pathways.