bluuebunny/crossref_metadata_2025 huggingface dataset:
The development and application of a decision support system for sustainable forest management on the Boreal Plain
Authors: Damme L Van , Russell J S , Doyon F , Duinker P N , Gooding T , Hirsch K , Rothwell R , Rudy A
Published: October 2003

Millar Western Forest Products Ltd. manages a forest in west-central Alberta under a Forest Management Agreement (FMA) with the Government of Alberta. Part of Millar Western's planning process brought researchers together to develop a decision support system (DSS) for forest management planning and monitoring programs. Four modules  timber supply, biodiversity, FIRE, and WATER  were built to evaluate, with the help of indicators of sustainable forest management, current and future forest conditions predicted from computer simulations of alternative management scenarios. In the first round of assessment four management scenarios, distinct by their level of silviculture intensification and by the spatial clearcut layout pattern, were compared. Such comparison has demonstrated that (1) the current forest management scenario improved moose habitat at the expense of timber supply, (2) all scenarios had similar fire risk, (3) generated increases in peak flow and water yield of selected watersheds, and (4) slightly impoverished forest biodiversity. All scenarios were examined in light of a computer-simulated natural disturbance benchmark. This led to landscape design scenarios to reduce fire risk and balance biodiversity indicators with timber supply objectives, one of which was eventually selected for implementation. The company's monitoring and research program is also highly focused on improving DSS modules and the underlying data, hence its association with the Forest Watershed and Riparian Disturbance (FORWARD) project, which considers the effects of forest management on aquatic ecosystem indicators. Key words: decision support system, ecosystem management, forest management, natural disturbance, indicators, sustainable forest management, adaptive management.
Modelling the effects of boreal forest landscape management upon streamflow and water quality: Basic concepts and considerations
Authors: Putz G , Burke J M , Smith Daniel W , Chanasyk D S , Prepas E E , Mapfumo E
Published: October 2003

Modelling and predicting potential impacts of forest harvest operations and wildfire on water quantity and quality are critical tools for forest managers. To make these predictions, the impacts of harvest operations and wildfire on model input parameters must first be quantified with measurements. In addition, output data are required to validate the model before any meaningful predictions can be made. This component of the Forest Watershed and Riparian Disturbance (FORWARD) project will closely associate hydrologic and water quality simulation modelling with intensive field monitoring of disturbance effects in forests of the Boreal Plain subregion of western Canada. The goal is to develop modelling procedures that can be used for predicting the impacts of forest operations and wildfires on water quantity and quality of stream runoff on the Boreal Plain. Key words: runoff, water quality, non-point source water quality modelling, hydrologic modelling, watershed management, riparian zone, forestry management.
Impact of wildfire on discharge and phosphorus export from the Sakwatamau watershed in the Swan Hills, Alberta, during the first two years
Authors: Prepas E E , Burke J M , Chanasyk D S , Smith Daniel W , Putz G , Gabos S , Chen W , Millions D , Serediak M
Published: October 2003

Water and phosphorus (P) exports during the peakflow season increased after a fire in early summer 1998 burned 89% of an upland watershed on the Boreal Plain of western Canada. The change in water export between pre- (1983) and post-fire (1998 to 2000) periods was higher in the burned (4th order) than reference stream (3rd order) (P = 0.01). Burned to reference stream ratios of particulate P (PP) flow-weighted mean concentrations (FWMC) and export were 1.5 and 2.8, respectively, in year 1 and 2.8 and 6.7, respectively, in year 2 post-fire. Particulate P comprised a similar proportion of total P export in the burned stream before fire and in the reference stream (65%), but a higher proportion after fire during the peakflow season only (77%) (P < 0.02). Phosphorus concentration and discharge (Q) were positively related in both streams, across all Q intensities measured in the case of dissolved P, but only at Q > 1.5 m3 s1 for PP. Changes in P export after fire were evident during peakflow and were largely restricted to the PP fraction. These changes appear to be driven by higher discharge, which enhanced loading of P-rich particulates from the watershed and (or) from the stream channel. Key words: watershed disturbance, watershed management, stream, water quality, fire, phosphorus, discharge.
Optimizing sugarbeet molasses distillery slops to olive mill husks ratio and incubation period for composting
Authors: Díaz M J , Madejón E , López R , Cabrera F
Published: October 2003

This paper analyzes the influence of operating conditions, such as mixing ratio of the waste ingredients and extension of the stabilization time, on the composting of sugarbeet molasses distillery slops (DS) and olive mill husks (OMH). The addition of 040% sugarbeet molasses DS to the starting mixtures and the treatment duration (40 d) were tested at the bench to optimize the process dynamics using the in-vessel composting method. Changes of compost stabilization conditions (organic matter, nitrogen losses, germination index) were also related to the characteristics of the different end products obtained. A second-order polynomial equation based on two independent process variables was developed to model the composting of sugarbeet molasses DS  OMH mixtures. Differences between experimental values and data derived by the application of the model never exceeded 10%. The best results in terms of biodegradation rate (i.e., degree of stabilization), maturity, and limitation of Kjeldahl-N losses were observed with process times of 3040 d and the addition of 010% sugarbeet molasses DS to OMH. Key words: biodegradability, compost, sugarbeet molasses distillery slops, olive mill husks.
Evaluation of the impact of design and operation parameters on direct filtration
Authors: Tchio Maurice , Koudjonou Boniface , Desjardins Raymond , Gadbois Alain , Prévost Michèle
Published: October 2003

This paper discusses the impacts of common design and operation parameters on direct filtration (DF) performance. These tests were carried out in a 45-m3/d pilot plant. The raw waters used were obtained by spiking a natural water with a kaolin suspension. The DF treatment comprises coagulation, flocculation, and filtration on a sand or anthracite bed. Seven parameters were studied over a wide range of design and operation conditions: effective size of the media (ES) 0.4 or 2.0 mm, depth of media (HMED) 50 or 300 cm, water head (WH) 50 or 300 cm, filtration rate (FR) 5 or 30 m/h, uniformity coefficient (UC) 1.3 or 1.5, raw water turbidity (TURB_RW) 1 or 5 nephelometric turbidity units (NTU), type of filtering media (MEDIA) sand or anthracite. The analysis of filter performance was based on the quantity and quality of filtered water produced and the cost of the filtration plant relative to each configuration. The results show that four of the parameters studied (ES, HMED, FR, and WH) have the most significant impacts on the filter performance and govern more than 77% of the performance criteria examined. This study also showed that the use of high-rate filtration increases the net productivity of the filters. However, to comply with filtered water quality requirements, the other three parameters should be set to appropriate values, since interactions among all four parameters are very high. The global cost analysis showed that a well designed and properly operated high-rate filtration process is more cost-effective than low-rate filtration. Key words: direct filtration, high-rate filters, cost analysis, statistical experimental design, Pareto chart.
Sodium azide interference in chemical and biological testing
Authors: Goel Ramesh K , Cooper Adrienne T , Flora Joseph R.V
Published: October 2003

This paper discusses the results of sodium azide interference encountered during lab-scale studies in which sodium azide was used as a microbial growth inhibitor. In separate tests to evaluate the oxidation of naphthalene by various oxidants, the disappearance of naphthalene in batch experiments containing chlorine was negligible after 12 d of incubation. However, 38% and 77% disappearance of naphthalene was observed when 11 mg/L of sodium azide was present in solutions containing 19.5 mg/L and 52.5 mg/L total chlorine, respectively. Chlorine was consumed faster in the batch studies containing sodium azide. Increasing levels of azide in solution also resulted in lower naphthalene and chlorine levels. In a separate set of experiments, sodium azide interfered with nitrate quantification and produced nitrate levels that were progressively lower with increasing azide concentrations. The decrease in nitrate was caused by reactions of sodium azide with nitrite formed during cadmium reduction. In both cases, sodium azide was added to the test solution either to prevent microbial growth or to inhibit existing microbial activity. These tests demonstrate that azide could potentially interfere in chemical and biological testing. Key words: sodium azide, inhibition, interference.
Release of phosphorus from biological nutrient removal sludges: A study of sludge pretreatment methods to optimize phosphorus release for subsequent recovery purposes
Authors: Liao P H , Mavinic Donald S , Koch Frederic A
Published: October 2003

As part of on-going studies related to developmentimplementation of new technologies and approaches for enhancing recovery of phosphorus from municipal wastes, the effectiveness of various methods of pretreating waste activated sludges (WASs) from a biological nutrient removal (BNR) process was investigated to determine suitable methods for maximizing phosphorus release. The additions of a strong base (NaOH), strong acid (HCl), organic acid (citric acid), and sodium acetate to waste sludge all facilitated the release of phosphate into solution. The maximum phosphate release was obtained by adding 4.9 mmole/L (~400 mg/L) of acetate to an intermittently mixed digester. Excess amounts of acetate did not further increase the phosphate concentrations. Acetate addition, which triggers carbon storage, a unique characteristic of enhanced biological phosphorus removal (EBPR) processes, releases internally stored phosphate compounds and is recommended as a method for releasing phosphates from EBPR sludges. Along with phosphates, various cations (most notably magnesium and potassium) were also mobilized and released into solution during digestion using acetate. These ions can be beneficially reused for struvite crystallization. Key words: acetate addition, caustic addition, phosphorus release, P-solubilization, sludge treatment, struvite.
Aerobic treatment of maize-processing wastewater (nejayote) in a single-stream multi-stage bioreactor
Authors: Salmerón-Alcocer Angélica , Rodríguez-Mendoza Norma , Pineda-Santiago Virgen , Cristiani-Urbina Eliseo , Juárez-Ramírez Cleotilde , Ruiz-Ordaz Nora , Galíndez-Mayer Juvencio
Published: October 2003

The manufacturing processes of tortillas, corn chips, tortilla chips, and related products yield a liquid waste called nejayote. This waste causes serious pollution problems since its chemical oxygen demand is very high, from 25000 to 30000 ppm. To reduce the pollution potential of this effluent, the use of a cascade of three continuous flow bioreactors-in-series is proposed in this work. When nejayote was supplemented with KH2PO4 and (NH4)2SO4, at COD:KH2PO4 and COD:(NH4)2SO4 ratios of 87 and 26, respectively, and the pH in the first stage was adjusted at 7.0 every 24 h, high removal efficiencies of COD (86.4%) and nitrogen (80.9%) were obtained. Although the treated water still requires a further treatment prior to its disposal, the proposed system is a potential alternative for nejayote treatment, since it allows a greater COD removal efficiency than those reported in the literature for equivalent organic loads. Key words: nejayote, biodegradation, multi-stage bioreactor, cascade.
Évaluation de l'adsorption de deux bactéries fécales par l'horizon argilo-sableux et l'horizon quartzo-feldspathique d'un sol ferralitique au Cameroun (Afrique Centrale)
Authors: Nola Moïse , Njiné Thomas , Servais Pierre , Messouli Mohamed , Boutin Claude , Menbohan Samuel Foto , Kemka Norbert , Zébazé Togouet Serge H
Published: October 2003

A laboratory study has been carried out to assess the retention capacity of Streptococcus faecalis and Escherichia coli by two ferralitic soil horizons: the upper soil horizon (HA), linked to the soil surface and of sandy-clayed texture, and the deeper soil horizon (HQ), related to the groundwater table and of quartzo-feldspathic texture. Bacterial sorption on soil particles swiftly took place during the first 30 min that followed mixture of bacteria to the aqueous medium containing soil. The number of adsorbed bacteria sometimes undergoes temporal fluctuations. From Freundlich isotherms used, the linear coefficient of HA led from 0.5139 to 0.8932 and that of HQ varied from 0.0634 to 0.5849. It was lower when E. coli and S. faecalis were present at the same time, and greater when S. faecalis only was present. The adsorption coefficient of HA varied from 174 to 49.55 x 106 bacteria/mg of soil, and that of HQ varied from 4026 to 13.74 x 104 bacteria/mg of soil. A low adsorption coefficient of HA is seen when S. faecalis only is present, and that of HQ is also low when E. coli only is present. In the presence of the two bacterial species, adsorption coefficients of the two soil horizons rises. Key words: Escherichia coli, Streptococcus faecalis, adsorption, sandy-clayed soil, quartzo-feldspathic soil.[Journal translation]
On the Quantization of Isomonodromic Deformations on the Torus
Authors: Korotkin D. , Samtleben H.
Published: October 2003

The quantization of isomonodromic deformation of a meromorphic connection on the torus is shown to lead directly to the Knizhnik–Zamolodchikov–Bernard equations in the same way as the problem on the sphere leads to the system of Knizhnik–Zamolodchikov equations. The Poisson bracket required for a Hamiltonian formulation of isomonodromic deformations is naturally induced by the Poisson structure of Chern–Simons theory in a holomorphic gauge fixing. This turns out to be the origin of the appearance of twisted quantities on the torus.
Stochastic Loop Equations
Authors: Antonov D. V.
Published: October 2003

Stochastic quantization is applied to derivation of the equations for the Wilson loops and generating functionals of the Wilson loops in the N = ∞ limit. These equations are treated both in the coordinate and momentum representations. In the first case the connection of the suggested approach with the problem of random closed contours and supersymmetric quantum mechanics is established, and the equation for the Quenched Master Field Wilson loop is derived. The regularized version of one of the obtained equations is presented and applied to derivation of the equation for the bilocal field correlator. The momentum loop dynamics is also investigated.
Operator Product Expansion, Heavy Quarks, QCD Duality and Its Violations
Authors: Chibisov B. , Dikeman R. D. , Shifman M. , Uraltsev N. G.
Published: October 2003

The quark(gluon)–hadron duality constitutes a basis for the theoretical treatment of a wide range of inclusive processes — from hadronic τ decays and Re+e- to semileptonic and nonleptonic decay rates of heavy flavor hadrons. A theoretical analysis of these processes is carried out by using the operator product expansion in the Euclidean domain, with subsequent analytic continuation to the Minkowski domain. We formulate the notion of the quark(gluon)–hadron duality in quantitative terms, then classify various contributions leading to violations of duality. A prominent role in the violations of duality seems to belong to the so-called exponential terms which, conceptually, may represent the (truncated) tail of the power series. A qualitative model, relying on an instanton background field, is developed, allowing one to get an estimate of the exponential terms. We then discuss a number of applications, mostly from heavy quark physics.
On ${\mathcal U}_h({\rm sl}(2))$, ${\mathcal U}_h(e(3))$ and Their Representations
Authors: Abdesselam B. , Chakrabarti A. , Chakrabarti R.
Published: October 2003

By solving a set of recursion relations for the matrix elements of the [Formula: see text] generators, the finite dimensional highest weight representations of the algebra were obtained as factor representations. Taking a nonlinear combination of the generators of the two copies of the [Formula: see text] algebra, we obtained [Formula: see text] algebra. The latter, on contraction, yields [Formula: see text] algebra. A nonlinear map of [Formula: see text] algebra on its classical analog e(3) was obtained. The inverse mapping was found to be singular. It signifies a physically interesting situation, where in the momentum basis, a restricted domain of the eigenvalues of the classical operators is mapped on the whole real domain of the eigenvalues of the deformed operators.
The UL(3) × UR(3) Extended Nambu–Jona-Lasinio Model in Differential Regularization
Authors: Chen Yaw-Hwang , Nyeo Su-Long , Yang Yeou-Wei
Published: October 2003

We employ the method of differential regularization to calculate explicitly the one-loop effective action of a bosonized UL(3) × UR(3) extended Nambu–Jona-Lasinio model consisting of scalar, pseudoscalar, vector and axial vector fields.
A Statistical Superfield and Its Observable Consequences
Authors: Allen Roland E.
Published: October 2003

A new kind of fundamental superfield is proposed, with an Ising-like Euclidean action. Near the Planck energy it undergoes its first stage of symmetry breaking, and the ordered phase is assumed to support specific kinds of topological defects. This picture leads to a low energy Lagrangian which is similar to that of standard physics, but there are interesting and observable differences. For example, the cosmological constant vanishes, fermions have an extra coupling to gravity, the gravitational interaction of W bosons is modified, and Higgs bosons have an unconventional equation of motion.
Liouville Type Models in the Group Theory Framework: I. Finite-Dimensional Algebras
Authors: Gerasimov A. , Kharchev S. , Morozov A. , Olshanetsky M. , Marshakov A. , Mironov A.
Published: October 2003

In this series of papers we represent the "Whittaker" wave functional of the (d + 1)-dimensional Liouville model as a correlator in (d + 0)-dimensional theory of the sine–Gordon type (for d = 0 and 1). The asymptotics of this wave function is characterized by the Harish-Chandra function, which is shown to be a product of simple Γ function factors over all positive roots of the corresponding algebras (finite-dimensional for d = 0 and affine for d = 1). This is in nice correspondence with the recent results on two- and three-point correlators in the 1+1 Liouville model, where emergence of peculiar double periodicity is observed. The Whittaker wave functions of (d + 1)-dimensional nonaffine ("conformal") Toda type models are given by simple averages in the (d + 0)-dimensional theories of the affine Toda type. This phenomenon is in obvious parallel with representation of the free field wave functional, which was originally a Gaussian integral over the interior of a (d + 1)-dimensional disk with given boundary conditions, as a (nonlocal) quadratic integral over the d-dimensional boundary itself. In this paper we concentrate on the finite-dimensional case. The results for finite-dimensional "Iwasawa" Whittaker functions are known, and we present a survey. We also construct new "Gauss" Whittaker functions.
V and A Structures of $t\bar{t}Z$ Vertex and Top Quark Polarization: QCD Corrections
Authors: Akatsu Yasunari , Terazawa Osamu
Published: October 2003

We calculate the energy distributions of leptons in semileptonic decay of t quarks in the process [Formula: see text], by taking into account the polarizations and spin–spin correlations of t and [Formula: see text] quarks with QCD corrections to the [Formula: see text] and [Formula: see text] vertices up to the order αs. The corrections are large to the t quark production cross-section but do not alter the energy distributions of final leptons of the parton model practically. The distributions will provide useful information about the V and A structures of t quark.
Fundamental Physics from Space and in Space
Authors: Jacob M.
Published: October 2003

Whereas most of the key questions in particle physics are still addressed with accelerators, one sees at present an increasing activity in cosmic rays, based on the use of large and sophisticated detectors on the ground and underground (or under water). A new discipline, "astroparticle physics" is born and rapidly expanding. Whereas much of this research is carried out on Earth, it is likely that part of it will eventually transfer to space. The detection of gravitational waves is now attempted with a new promising vigor, using interferometers. This physics at present on the ground will have to extend to space. The talk reviews facts and trends in this research in fun damental physics from space now, but increasingly in space later on.
D Branes from Liouville Strings
Authors: Ellis John , Mavromatos N. E. , Nanopoulos D. V.
Published: October 2003

We develop quantization aspects of our Liouville approach to noncritical strings, proposing a path-integral formulation of a second quantization of string theory, that incorporates naturally the couplings of string sources to background fields. Such couplings are characteristic of macroscopic string solutions and/or D-brane theories. Resummation over world-sheet genera in the presence of stringy (σ-model) soliton backgrounds, and recoil effects associated with logarithmic operators on the world sheet, play a crucial role in inducing such sources as well-defined renormalization-group counterterms. Using our Liouville renormalization group approach, we derive the appropriate second-order equation of motion for the D brane. We discuss within this approach the appearance of open strings, whose ends carry nontrivial Chan–Paton-like quantum numbers related to the W∞ charges of two-dimensional string black holes.
Integrable Boundary Conditions Associated with the Zn × Zn Belavin Model and Solutions of Reflection Equation
Authors: Fan Heng , Shi Kang-Jie , Hou Bo-Yu , Yang Zhong-Xia
Published: October 2003

We construct solvable models with nontrivial boundary from the well known Belavin R-matrix. The reflection equation for the boundary reflection matrix is studied and the complete solution for the one associated with the eight-vertex model is found.
Classical Integrability of the O(N) Nonlinear Sigma Model on a Half-Line
Authors: Corrigan E. , Sheng Z.-M.
Published: October 2003

The classical integrability of the O (N) nonlinear sigma model on a half-line is examined, and the existence of an infinity of conserved charges in involution is established for the free boundary condition. For the case N = 3 other possible boundary conditions are considered briefly.
From Inflationary COBE Potentials to Higher-Order Curvature Scalar Lagrangians
Authors: Benítez Javier , Macías Alfredo , Mielke Eckehard W. , Obregón Octavio , Villanueva Victor M.
Published: October 2003

Within Einstein's general relativity, a new method of reconstructing the inflaton potential U(ϕ) has been developed which, in principle, is applicable to any order of the slow-roll approximation. For the resulting second order nonlinear differential equation we found a new solution for which the spectral index of scalar perturbations is completely fixed as ns = 1.49575. This value fits quite well to recent COBE and other astrophysical observations. Via a Legendre transformation, we are able to reconstruct and visualize the corresponding nonlinear curvature scalar Lagrangian L(R) in which the inflaton is absorbed by means of a conformal mapping.
The Gunn–Peterson Effect: A Test for a Black-Hole-Induced Photoionization of the Intergalactic Medium
Authors: Gibilisco Marina
Published: October 2003

There are many experimental evidences of the presence of an ionizing background radiation flux at large redshifts, whose nature is doubtful. A lot of information about the characteristics of such a background can be obtained both from the study of the Gunn–Peterson effect and from the so-called "proximity effect."

In some previous works I suggested the possibility that this ionizing flux comes from the quantum evaporation of primordial black holes (PBH's); here, I discuss the constraints that the experimental measurements put upon the free parameters of this reionization model and I try to verify its reliability. In particular, the radiation intensity of the background at the hydrogen Lyman edge, as inferred from the proximity effect, enables me to determine an upper limit to the PBH's average relic mass; due to our poor knowledge of the ultimate fate of the evaporating black holes, this limit represents an important theoretical information. In the second part of this paper I study the absorption of the ionizing background due to Lyα clouds: in particular, I discuss this phenomenon in the presence of different absorption levels and I calculate the HI Gunn–Peterson optical depth τ GP (z); from a comparison with the experimental data of Giallongo et al.(τ GP, HI < 0.02 ± 0.03) I obtain a constraint on the intergalactic medium density parameter, namely Ω IGM < 0.020.

A study of the characteristics of the absorbers is also performed: I determine the hydrogen gas density nH,c and the column density N HI for Lyα clouds; a satisfactory agreement with the available experimental data is obtained in the case of expanding, adiabatically cooled clouds. Finally, the same kind of analysis is performed for He II: in this case, the theoretical optical depth I obtain is smaller than the preliminary experimental lower limit of Jakobsen et al.(τ GP > 1.7).
Asymptotic Conformal Invariance of SU(2) and Standard Models in Curved Space–Time
Authors: Yoon Youngsoo , Yoon Yongsung
Published: October 2003

The asymptotic conformal invariance of some SU(2) model and Standard Model in curved space–time are investigated. We have examined the conditions for asymptotic conformal invariance for these models numerically.
A Family of Unitary Higher Order Equations
Authors: Bollini C. G. , Oxman L. E. , Rocca M. C.
Published: October 2003

A scalar field obeying a Lorentz invariant higher order wave equation, is minimally coupled to the electromagnetic field. The propagator and vertex factors for the Feynman diagrams, are determined. As an example we write down the matrix element for the Compton effect. This matrix element is algebraically reduced to the usual one for a charged Klein–Gordon particle. It is proven that the nth order theory is equivalent to n independent second order theories. It is also shown that the higher order theory is both renormalizable and unitary for arbitrary n.
Fusion for the Function Difference Representation of Zn Sklyanin Algebra
Authors: Hou Bo-Yu , Shi Kang-Jie , Yang Wen-Li , Yang Zhong-Xia , Zhou Shan-You
Published: October 2003

We study the fusion of function difference representation (FR) and cyclic representation (CR) of Zn Sklyanin algebra (SA). Using this fusion procedure with certain functions, we derive some finite-dimensional representations of SA. We obtain a conjugate FR and a new FR of SA. We also give automorphisms and an antiautomorphism of Zn SA.
BRST and Anti-BRST Symmetry in Topological BF Theories
Authors: Tahiri M.
Published: October 2003

We realize the quantization of arbitrary-dimensional non-Abelian BF theories from the point of view of both the BRST symmetry and anti-BRST symmetry. The method relies on the possibility of enlarging the system of fields occurring in such theories by auxiliary fields introduced geometrically in terms of a superspace formalism. The off-shell nilpotency of the BRST and anti-BRST transformations of these fields is automatically guaranteed, thanks to the structure equations and the Bianchi identities. From this follows a direct construction of the BRST invariant full quantum action which leads, after the elimination of the auxiliary fields, to the same quantum action obtained in the context of the Batalin–Vilkovisky formalism. We also discuss how the constructed BRST invariant quantum action is anti-BRST invariant. In addition, we show that the non-Abelian BF theory in any space–time dimension possesses a vector supersymmetry of ghost number +1.
On Chiral p-Forms
Authors: Bengtsson Ingemar , Kleppe Astri
Published: October 2003

Some aspects of chiral p-forms, in particular the obstruction that makes it hard to define covariant Green functions, are discussed. It is shown that a proposed resolution involving an infinite set of gauge fields can be made mathematically rigorous in the classical case. We also give a brief demonstration of species doubling for chiral bosons.
Nonperturbative Effects in 2D String Theory or, Beyond the Liouville Wall
Authors: Brustein Ram , Ovrut Burt A.
Published: October 2003

We discuss continuous and discrete sectors in the collective field theory of D = 1 matrix models. A canonical Lorentz-invariant field theory extension of collective field theory is presented and its classical solutions in Euclidean and Minkowski space are found. We show that the discrete, low density sector of collective field theory includes single eigenvalue Euclidean instantons which tunnel between different vacua of the extended theory. We further show that these "stringy" instantons induce nonperturbative effective operators of strength [Formula: see text] in the extended theory. The relationship of the world sheet description of string theory and Liouville theory to the effective space–time theory is explained. We also comment on the role of the discrete, low density, sector of collective field theory in that framework.
Euclidean Quantum Wormholes with Scalar Fields
Authors: Carlini A. , Coule D. H. , Solomons D. M.
Published: October 2003

We consider the quantum analogs of Euclidean wormholes obtained by Carlini and Mijić (CM), who analytically continued recollapsing closed universe models. Using a perfect fluid matter source, we obtain asymptotically Euclidean (AE) wormholes when the strong energy condition is satisfied. Such wormholes are found to be consistent with the Hawking–Page (HP) conjecture for quantum wormholes as solutions of the Wheeler–DeWitt (WDW) equation.

By simulating the equation of state of a perfect fluid with a real scalar field, quantum wormholes are also found when the strong energy condition is violated, although generally not AE. The non-AE solutions are interpreted as excited states of the quantum wormhole spectrum.

Our results give support to the claim of HP that quantum wormhole solutions are a fairly general property of the WDW equation for various matter sources. Matter sources giving quantum wormholes could now include those expected in low energy effective string theory: a dilaton scalar field with exponential potential. This is unlike the classical case where such matter sources do not allow wormhole solutions.

We finally contrast quantum wormhole solutions with other boundary conditions of quantum cosmology describing an inflationary earlier behavior and a resulting large Lorentzian universe phase.
A Sterile Neutrino Scenario Constrained By Experiments and Cosmology
Authors: Okada Nobuchika , Yasuda Osamu
Published: October 2003

We analyze a scheme in which three active neutrinos and one sterile neutrino account for the solar, the atmospheric and the LSND neutrino anomalies in a model-independent way. It is shown that if the equivalent number, Nν, of the light neutrino species is less than 4, then the constraints from these anomalies, accelerator and reactor experiments and big bang nucleosynthesis force a general 4 × 4 mixing matrix to be effectively split into two 2 × 2 matrices. If these neutrinos are of the Majorana type, then negative results of neutrinoless double beta decay experiments imply that the total mass of neutrinos is not sufficient to account for all the hot dark matter components.
Logarithmic Operators in Conformal Field Theory and the ${\mathcal W}_\infty$-Algebra
Authors: Shafiekhani A. , Rahimi Tabar M. R.
Published: October 2003

It is shown explicitly that the correlation functions of conformal field theories (CFT) with the logarithmic operators are invariant under the differential realization of Borel subalgebra of [Formula: see text]-algebra. This algebra is constructed by tensor-operator algebra of differential representation of ordinary [Formula: see text]. This method allows us to write differential equations which can be used to find general expression for three- and four-point correlation functions possessing logarithmic operators. The operator product expansion (OPE) coefficients of general logarithmic CFT are given up to third level.
Linked Cluster Expansions Beyond Nearest Neighbor Interactions: Convergence and Graph Classes
Authors: Pordt Andreas , Reisz Thomas
Published: October 2003

We generalize the technique of linked cluster expansions on hypercubic lattices to actions that couple fields at lattice sites which are not nearest neighbors. We show that in this case the graphical expansion can be arranged in such a way that the classes of graphs to be considered are identical to those of the pure nearest neighbor interaction. The only change then concerns the computation of lattice imbedding numbers. All the complications that arise can be reduced to a generalization of the notion of free random walks, including hopping beyond nearest neighbor. Explicit expressions for combinatorical numbers of the latter are given. We show that under some general conditions the linked cluster expansion series have a nonvanishing radius of convergence.
Central Extension of Extended Supergravities in Diverse Dimensions
Authors: Andrianopoli Laura , D'Auria Riccardo , Ferrara Sergio
Published: October 2003

We generalize central-charge relations and differential identities of N = 2 special geometry to N extended supergravity in any dimension 4 ≤ D < 10, and p-extended objects. We study the extremization of the ADM mass per unit of p-volume of BPS extended objects. Runaway solutions for a "dilaton" degree of freedom leading to a vanishing result are interpreted as BPS extremal states having vanishing Bekenstein–Hawking entropy.
The Influence of Quarks and Gluons Jets Coming from Primordial Black Holes on the Reionization of the Universe
Authors: Gibilisco Marina
Published: October 2003

In a previous work, I discussed the effect of the primordial black holes (PBH's) quantum evaporation on the reionization of the Universe at small redshifts (z ≤ 60): in principle, the photons emitted during the evaporation of such objects could drive a new ionization for the Universe after the recombination epoch; this reionization process should happen during the last stages of the PBH's life, when they totally evaporate and emit a lot of massive and massless particles. The critical mass of a black hole whose lifetime is equal to the present age of the Universe is ~ 4.4 × 1014 h-0.3 g: thus, PBH's having a mass M ~ 1014 g are the ideal candidates to induce a reionization at small redshifts. While in my previous study, I considered an exact blackbody photon emission spectrum, here I will adopt a more realistic one, taking into account the quarks and gluons jets emission through the contribution of a known fragmentation function. When the BH temperature rises above the QCD confinement scale, ΛQCD, one should expect an important contribution from quarks and gluons emission in the form of jets. In this paper I also improved my analysis by considering without any approximation the cooling effects in the plasma temperature evolution; as a result, I obtained a satisfactory "late and sudden" reionization process, characterized by a very well controlled rise of the plasma temperature: the plasma heating is not so high to induce a strong distortion of the CBR spectrum, in agreement with the recent FIRAS upper limit on the comptonization parameter, yc < 2.5 × 10-5.
On the Minimal Model of Anyons
Authors: Gorbunov I. V. , Kuzenko S. M. , Lyakhovich S. L.
Published: October 2003

We present a geometric formulation for the fractional spin particle models on the minimal phase–spaces. Consistent couplings of the anyon to background fields are constructed. The relationship between our approach and previously developed anyon models is discussed. We also demonstrate the canonical equivalence in the class of the minimal anyon models with nontimelike spin vector, which were independently considered before.
Parasupersymmetries and Non-Lie Constants of Motion for Two-Particle Equations
Authors: Nikitin A. G. , Tretynyk V. V.
Published: October 2003

We search for hidden symmetries of two-particle equations with oscillator-equivalent potential, proposed by Moshinsky with collaborators. We proved that these equations admit hidden symmetries and parasupersymmetries which enable one to easily find the Hamiltonian spectra using algebraic methods and to construct exact Foldy–Wouthuysen transformations. Moreover, we demonstrate that these equations are reducible and generate Hamiltonians for pararelativistic or Kemmer oscillators. We also establish equivalence relations between different approaches to Kemmer oscillator and propose new one- and two-particle equations with oscillator-equivalent potentials.
Chiral Symmetry Breaking in Strongly Coupled U(1) Gauge Theory Coupled to Scalar and Fermion Matter
Authors: Chemtob M. , Langfeld K.
Published: October 2003

We construct a transformation for scalar QED (U(1) gauge theory coupled with a charged scalar field) which leads to a dual effective gauge theory having a perturbation theory expansion in inverse powers of the (electric charge) coupling constant. The dual formulation is applied to the special case of scalar QED coupled to a massless charged fermion. A four-fermion interaction term arises naturally under the duality mapping. As an extension to discussions initiated by Miransky, Bardeen and Kondo and their collaborators in the late 1980's, we use this formulation to explore the possibility of a dynamical breakdown of chiral symmetry for the strongly coupled U(1) gauge theory interacting with both scalar and fermion degrees of freedom. Assuming that scalar QED is realized in the Higgs phase, we examine the Schwinger–Dyson equation approach to the fermion propagator in next-to-leading order of the strong coupling expansion (quenched approximation, i.e. no fermion loops). We construct a consistent renormalization procedure to deal with the ultraviolet infinities. For fixed scalar field vacuum expectation values, we obtain in the plane of the two important parameters of the theory (electric charge and four-fermion coupling constant) critical transition lines to a chirality broken phase.
Increasing Potentials in Classical Non-Abelian and Abelian Gauge Theories
Authors: Singleton D. , Yoshida A.
Published: October 2003

An exact solution for an SU(2) Yang–Mills field coupled to a scalar field is given, which has potentials with linear, 1/r and 1/r2 parts. This may be of some interest since some phenomenological QCD studies assume a linear plus Coulomb potential. We also show that in the Nielsen–Olesen Abelian model there is an exact solution in the BPS limit, which has a 1/r electromagnetic field and a logarithmically rising scalar field. Both of these solutions must be cutoff from above to avoid infinite field energy.
The Batalin–Tyutin Formalism on the Collective Coordinates Quantization of the SU(2) Skyrme Model
Authors: Oliveira Wilson , Neto Jorge Ananias
Published: October 2003

We apply the Batalin–Tyutin constraint formalism of converting a second class system into a first class system for the rotational quantization of the SU(2) Skyrme model. We obtain the first class constraints, the Hamiltonian in the extended phase space, the Lagrangian that leads the new theory and the spectrum of the extended theory. We observe that with the use of the BT formalism on the collective coordinates quantization of the SU(2) Skyrme model there is an additional term in the usual quantum Hamiltonian.
Spontaneous Compactification Induced by Gravitons and Scalar Field
Authors: Granda N. , Loaiza E.
Published: October 2003

We evaluate the one-loop effective potential for the Einstein–Hilbert action coupled to a nonlinear sigma model in a Kaluza–Klein background space M4 × SN (M4 is the four-dimensional Minkowski space–time and SN is the N-dimensional sphere) for odd N. The computation is made in the harmonic and in the light cone gauges. The radius of compactification for some N was found.
The Power of Duality — Exact Results in 4D SUSY Field Theory
Authors: Seiberg N.
Published: October 2003

Recently the vacuum structure of a large class of four-dimensional (supersymmetric) quantum field theories was determined exactly. These theories exhibit a wide range of interesting new physical phenomena. One of the main new insights is the role of "electric–magnetic duality." In its simplest form it describes the long distance behavior of some strongly coupled, and hence complicated, "electric theories" in terms of weakly coupled "magnetic theories." This understanding sheds new light on confinement and the Higgs mechanism and uncovers new phases of four-dimensional gauge theories. We review these developments and speculate on the outlook.
Twisted Quantum Lax Equations
Authors: Jurčo Branislav , Schupp Peter
Published: October 2003

We show the construction of twisted quantum Lax equations associated with quantum groups, and solve these equations using factorization properties of the corresponding quantum groups. Our construction generalizes in many respects the AKS construction for Lie groups and the construction of M. A. Semenov-Tian-Shansky for the Lie–Poisson case.
Noncommutative Symmetric Functions II: Transformations of Alphabets
Authors: Krob D. , Leclerc B. , Thibon J.-Y.
Published: October 2003

Noncommutative analogues of classical operations on symmetric functions are investigated, and applied to the description of idempotents and nilpotents in descent algebras. It is shown that any sequence of Lie idempotents (one in each descent algebra) gives rise to a complete set of indecomposable orthogonal idempotents of each descent algebra, and various deformations of the classical sequences of Lie idempotents are obtained. In particular, we obtain several q-analogues of the Eulerian idempotents and of the Garsia-Reutenauer idempotents.
On the Combination Theorem for Negatively Curved Groups
Authors: Gitik Rita
Published: October 2003

We give a simple proof of a sufficient condition for an amalgamated free product of two negatively curved groups to be negatively curved, and we compute the curvature of such products.
On the Algebra of Semigroup Diagrams
Authors: Kilibarda Vesna
Published: October 2003

In this work we enrich the geometric method of semigroup diagrams to study semigroup presentations. We introduce a process of reduction on semigroup diagrams which leads to a natural way of multiplying semigroup diagrams associated with a given semigroup presentation.

With respect to this multiplication the set of reduced semigroup diagrams is a groupoid. The main result is that the groupoid [Formula: see text] of reduced semigroup diagrams over the presentation S =  may be identified with the fundamental groupoid γ (KS) of a certain 2-dimensional complex KS. Consequently, the vertex groups of the groupoid [Formula: see text] are isomorphic to the fundamental groups of the complex KS. The complex we discovered was first considered in the paper of Craig Squier, published only recently. Steven Pride has also independently defined a 2-dimensional complex isomorphic to KS in relation to his work on low-dimensional homotopy theory for monoids.

Some structural information about the fundamental groups of the complex KS are presented. The class of these groups contains all finitely generated free groups and is closed under finite direct and finite free products. Many additional results on the structure of these groups may be found in the paper of Victor Guba and Mark Sapir.
Torsion Groups of Elliptic Curves with Integral j-Invariant over General Cubic Number Fields
Authors: Pethö Attila , Weis Thomas , Zimmer Horst G.
Published: October 2003

In [15] and [16] all possible torsion groups of elliptic curves E with integral j-invariant over quadratic and pure cubic number fields K are determined. Moreover, with the exception of the torsion groups of isomorphism types ℤ/2ℤ, ℤ/3ℤ and ℤ/2ℤ×ℤ/2ℤ, all elliptic curves E and all basic quadratic and pure cubic fields K such that E over K has one of these torsion groups were computed. The present paper is aimed at solving the corresponding problem for general cubic number fields K. In the general cubic case, the above groups ℤ/2ℤ, ℤ/3ℤ and ℤ/2ℤ×ℤ/2ℤ and, in addition, the groups ℤ/4ℤ, ℤ/5ℤ occur as torsion groups of infinitely many curves E with integral j-invariant over infinitely many cubic fields K. For all the other possible torsion groups, the (finitely any) elliptic curves with integral j over the (finitely many) cubic fields K are calculated here. Of course, the results obtained in [6] for pure cubic fields and in [24] for cyclic cubic fields are regained by our algorithms. However, compared with [15] and [6], a solution of the torsion group problem in the much more involved general cubic case requires some essentially new methods. In fact we shall use Gröbner basis techniques and elimination theory to settle the general case.
Self-Rectangulating Varieties of Type 5
Authors: Kearnes Keith A. , Szendrei Ágnes
Published: October 2003

We show that a locally finite variety which omits abelian types is self-rectangulating if and only if it has a compatible semilattice term operation. Such varieties must have type-set {5}. These varieties are residually small and, when they are finitely generated, they have definable principal congruences. We show that idempotent varieties with a compatible semilattice term operation have the congruence extension property.
On the Structure of Inverse Semigroup Amalgams
Authors: Bennett Paul
Published: October 2003

This paper is the second of two papers devoted to the study of amalgamated free products of inverse semigroups. We use the characterization of the Schützenberger automata given previously by the author to obtain structural results and preservational properties of lower bounded amalgams. Haataja, Margolis and Meakin have shown that if [S1,S2;U is an amalgam of regular semigroups in which S1∩ S2=U is a full regular subsemigroup of S1 and S2, then the maximal subgroups of the amalgamated free product S1*U S2 may be described by the fundamental groups of certain bipartite graphs of groups. In this paper we show that the maximal subgroups of a lower bounded amalgam [S1,S2;U] are either isomorphic copies of subgroups of S1 and S2 or can be described by the same Bass-Serre theory characterization. It follows, as for the regular case, that if S1 and S2 are combinatorial, then the maximal subgroups of S1*U S2 are free. By studying the endomorphism monoids of the Schützenberger graphs we obtain a number of results concerning when inverse semigroup properties are preserved under the amalgamated free product construction. For example, necessary and sufficient conditions are given for S1*U S2 to be completely semisimple. Under a mild assumption we establish necessary and sufficient conditions for S1*U S2 to have finite ℛ-classes. This enables us to reprove a result of Cherubini, Meakin and Piochi on amalgams of free inverse semigroups. Finally we give sufficient conditions for S1*U S2 to be E-unitary.