bluuebunny/crossref_metadata_2025 huggingface dataset:
Seasonal pattern of water depletion from soil–rock profiles in a Mediterranean climate in southwestern Oregon
Authors: Zwieniecki Maciej A. , Newton Michael
Published: September 2007

Neutron probe measurements from aluminum access tubes (3.2 m deep) show that conifers and sclerophyllous shrubs deplete water from soil–rock profiles in distinctly different patterns. Measurements were taken during two growing seasons (1993 and 1994) in southwestern Oregon (U.S.A.) under 14-year-old stands of Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco), ponderosa pine (Pinusponderosa Dougl. ex Laws.), Pacific madrone (Arbutusmenziesii Pursh), and whiteleaf manzanita (Arctostaphylosviscida Parry) covers. Both conifer species showed very limited abilities to utilize water from bedrock, even during very dry periods. Ericaceous plants, on the other hand, were very efficient in taking water from the deep rock layers, using nearly all available water and removing about twice as much water as conifers of the same age. Patterns of water depletion suggest that the water resources used by these two types of plants overlap considerably, and competition will be very strong in mixed stands. The ability of ericaceous plants to utilize bedrock water that is unavailable to conifers in late summer will enhance their potential for dominance.
The ecophysiological and growth responses of Aleppo pine (Pinushalepensis) to controlled heating applied to the base of the trunk
Authors: Ducrey Michel , Duhoux Fabrice , Huc Roland , Rigolot Eric
Published: September 2007

Controlled, localized heating was applied to the trunks of young Aleppo pines (Pinushalepensis Mill.) during the winter. Three levels of burning were applied to the circumference of the trunks (zero, partial, or total), and the effects on tree physiology and growth were monitored during the 7 months following heating. Effects of the heat treatment on tree physiology were assessed by measuring predawn water potential, sap flux density, microvariations in trunk diameter, electrical resistance of the cambium, and gas exchanges from the needles (photosynthesis and stomatal conductance). Morphological response measurements included height and radial growth of the trees and morphological characteristics of the needles. The amount of chlorotic foliage was also measured. Aleppo pine was highly resistant to trunk injury, surviving when 80% of the trunk circumference was destroyed by fire. The behaviour of partially burnt pines was not significantly different from that of controls, for all variables studied. Trees whose trunks were totally burnt died from 1 to 5 months after treatment. Sap flux density of totally burnt trees was already significantly lower than that of other trees in the first week following the treatment. A decrease in net photosynthesis and stomatal conductance in the still surviving totally burnt trees was also recorded during the first measurements made in July. Treatment differences in predawn water potential, microvariations in trunk diameter, and electrical resistance of the cambium only appeared a few days before death of the totally burnt trees.
Decadal-scale dynamics at the Gus Pearson Natural Areas: evidence for inverse (a)symmetric competition?
Authors: Biondi Franco
Published: September 2007

The Gus Pearson Natural Area is one of the longest maintained individual-based forest-monitoring sites in the world. It is an 800 × 400 m plot established in 1908 within pristine ponderosa pine (Pinusponderosa Dougl. ex Laws, van scopulorum) forest near Flagstaff, Arizona. I quantified decadal-scale growth trends of individual trees and of the entire stand from timber inventories repeated at 10-year intervals between 1920 and 1990. A mixed linear model for longitudinal data was used to test significance of temporal trends. Stand density increased throughout the 20th century because of successful regeneration pulses, active fire control, and no tree cutting. Aboveground growth rates of the stand as a whole did not change significantly from 1920 to 1990, but individual growth rates declined. Mixed linear model results indicated that decadal basal area increment of large pines declined more than that of small pines. In 1920–1930 large pines were growing faster than small pines, but by 1980–1990 large pines were growing slower than small pines. Since the number of small pines multiplied and the number of large pines changed slightly, I inferred that competition for resources was more detrimental for large pines than for small pines.
Growth intercept models for species without distinct annual branch whorls: western hemlock
Authors: Nigh Gordon D.
Published: September 2007

A growth intercept model is presented that is designed to estimate site index for juvenile stands of species without distinct annual branch whorls. It is called a variable growth intercept model and is demonstrated on western hemlock (Tsugaheterophylla (Raf.) Sarg.). The growth intercept is calculated from all the growth above breast height (hence the name variable), not just a fixed number of years' growth above breast height as is traditionally done. This technique gives more flexibility in using growth intercepts to estimate site index. It can also lead to more accurate estimates of site index because it incorporates more growth information.
Freezing temperatures and exposure times during bud break and shoot elongation influence survival and growth of containerized black spruce (Piceamariana) seedlings
Authors: Bigras Francine J. , Hébert Carole
Published: September 2007

Spring frosts frequently cause significant damage to conifer seedlings during bud flushing and shoot elongation in forestry nurseries. To insure adequate protection, levels of frost sensitivity must be known during these stages of development. Eight- or 9-month-old containerized black spruce seedlings (Piceamariana (Mill.) BSP) were submitted to freezing temperatures of 0° to −10 °C for 1–6 h at the following stages: (1) nonswollen terminal buds, (2) swollen terminal buds, (3) terminal bud scales bursting, needle tips emerging, and (4) shoots elongating, 1−5 cm. After freezing, seedlings were grown for 130 days in a greenhouse. Seedling survival was estimated; dead seedlings discarded; and damage to buds, needles, and roots as well as diameter and shoot increment were measured on the remaining seedlings. Frost sensitivity increased as buds flushed and new shoots elongated. Decreased seedling and bud survival was noted with increasing time of freezing exposure and decreasing temperature in stages 2, 3, and 4. Damage to needles and roots increases, while diameter decreases, with decreasing temperatures at all stages; however, shoot increment was influenced by decreasing temperatures only at stages 2 and 3.
Structure of mixed pine and hardwood stands 12 years after various methods and intensities of site preparation in the Georgia Piedmont
Authors: Harrington Timothy B. , Edwards M. Boyd
Published: September 2007

In the Georgia Piedmont (U.S.A.), size, abundance, and species diversity of trees were quantified in a plantation of Pinustaeda L. 12 years after various methods and intensities of site preparation. In clear-cut only versus site-prepared plots, greater hardwood abundance (27% vs. 8% of the total basal area) and size (8.6 vs. 7.4 m in height) were associated with reduced pine volume (73 vs. 123 m3/ha) and increased Simpson and Shannon diversity indices. Tree-species richness was greater in plots where residual trees from clear-cutting had been removed with a chainsaw versus large machinery (10 vs. 7 species). With increasing site-preparation intensity, reductions in basal area of volunteer pines coincided with proportionate increases (R2 = 0.80) in basal area of planted pines. As a result of this compensatory effect, total volume of all pines varied little (122–134 m3/ha) among site-preparation intensities. Research results suggest that site-preparation treatments can be selected to facilitate the development of a variety of stand structures, including those that favor evenness (clear-cut only) or richness (manual cutting) of tree species, low-cost production of pine fiber (manual cutting), and stand uniformity for management of pine sawtimber (mechanical and herbicide).
Frost hardiness of Thujaplicata and Pseudotsugamenziesii seedlings when nutrient supply varies with season
Authors: Hawkins B.J. , Henry G. , Whittington J.
Published: September 2007

Seedlings of coastal Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and western redcedar (Thujaplicata Donn ex D. Don) were subject to three nutrient treatments varying the rate of application of nitrogen (N) and phosphorus (P) over the growing season. A control treatment provided seedlings with a constant supply of N and P. A high–low treatment reduced the rate of N and P supply after mid-July. A low–high treatment initially supplied seedlings with low amounts of N and P, and then increased the rate of supply after mid-July. Foliar nutrient concentration of seedlings of each species from each nutrient treatment was measured in September and the following April. Cold tolerance of seedlings was assessed five times over the winter season by freeze-induced electrolyte leakage and twice by differential scanning calorimetry (DSC). Nutrient treatment did not significantly affect foliar nutrient concentration in either species. Height of Douglas-fir seedlings was also unaffected by nutrient treatment, but western redcedar seedlings in the control treatment were 6.3 cm taller than those in the high–low treatment. Interpolated damage at −13 °C from freeze-induced electrolyte leakage indicated that Douglas-fir seedlings from the control treatment had 19.8% less damage than high–low seedlings in October, 18% less damage in November, and 1.6% less damage in December. The same trend was evident, although not always significant, in western redcedar. Differential scanning calorimetry analyses of Douglas-fir in October and November showed freezing and melting curve onset and peak temperatures to be, on average, 2.3 °C and 0.4 °C warmer, respectively, in control seedlings than in high–low plants.
Pistillate flower development in eastern black walnut
Authors: Schaffer Karen L. , George Milon F. , Peleg Michael , Garrett H. Eugene , Cecich Robert A.
Published: September 2007

Preliminary observations of terminal bud development in eastern black walnut (Juglansnigra L. cv. Ogden) were made from midwinter through early May of 1987 using light microscopy. Flattened meristems, characteristic of pistillate flower initiation, were present in late February. Pistillate flower differentiation progressed significantly during early and mid-April, with sepal and ovule development being evident. Terminal bud swelling was clearly visible by the last week of April, and pistillate flowers were fully expanded by the first week of May. During the spring of 1988, a more detailed sequence of pistillate flower formation was recorded. In mid-April, pistillate flower meristems were clearly present and were enclosed in involucre tissue. Sepal development was also evident. By the end of April, a single pistil had emerged in the center of the meristem. As development continued, a single orthotropous ovule was formed and was surrounded by one integument. Concomitant with the growth of the ovule during early May, stigmatic regions enlarged, involutions developed, and vascular tissue became differentiated. Blooming occurred during the 2nd and 3rd weeks of May. During the 3rd and 4th weeks of May fertilized flowers with endosperm tissue were observed. In 1991, field observations of bud swell, catkin development, bud break, stem elongation, leaf expansion, and pistillate flower development were made to supplement the histological observations made in 1988. Overall, the developmental sequence of pistillate flower formation is similar to that of protandrus cultivars of English walnut (Juglansregia L.).
TOPOLOGICAL OBJECTS IN THE O(3) NONLINEAR SIGMA MODEL
Authors: ZHANG PENG-MING , LEE XI-GUO , WU SHAO-FENG , DUAN YI-SHI
Published: September 2007

We study the topological defects in the nonlinear O(3) sigma model in terms of the decomposition of U(1) gauge potential. Time-dependent baby skyrmions are discussed in the (2+1)-dimensional spacetime with the CP1 field. Furthermore, we show that there are three kinds of topological defects–vortex lines, point defects and knot exist in the (3+1)-dimensional model, and their topological charges, locations and motions are determined by the ϕ-mapping topological current theory.
A REVIEW OF SPIN DETERMINATION AT THE LHC
Authors: YAVIN ITAY
Published: September 2007

We review the prospects of direct spin determination of new particles which may be discovered at the LHC. We discuss the general framework and the different channels which contain spin information. The experimental challenges associated with such measurements are briefly discussed and the most urgent unresolved problems are emphasized.
PERIODIC SOLUTIONS AND SLOW MANIFOLDS
Authors: VERHULST FERDINAND
Published: September 2007

After reviewing a number of results from geometric singular perturbation theory, we give an example of a theorem for periodic solutions in a slow manifold. This is illustrated by examples involving the van der Pol-equation and a modified logistic equation. Regarding nonhyperbolic transitions we discuss a four-dimensional relaxation oscillation and also canard-like solutions emerging from the modified logistic equation with sign-alternating growth rates.
BIFURCATION BEHAVIOR OF THE FURUTA PENDULUM
Authors: MUÑOZ-ALMARAZ F. J. , FREIRE E. , GALÁN-VIOQUE J.
Published: September 2007

The dynamical behavior of a simple pendulum hanging from a rotating arm has been investigated. The system is invariant under rotations around the axis and can be formulated as a two-degrees of freedom integrable Hamiltonian system in the absence of external forcing. The bifurcation diagram is organized around the relative equilibria (solutions that are invariant under the symmetry) and bridges connecting different bifurcation points. Special attention has been given to those solutions that could shed some light into the stabilization of the upside down solution and the control problem.
CONTROL-BASED CONTINUATION OF PERIODIC ORBITS WITH A TIME-DELAYED DIFFERENCE SCHEME
Authors: SIEBER J. , KRAUSKOPF B.
Published: September 2007

This paper presents a method that is able to continue periodic orbits in systems where only output of the evolution over a given time period is available, which is the typical situation in an experiment. The starting point of our paper is an analysis of time-delayed feedback control, a method to stabilize periodic orbits experimentally that is popular among physicists. We show that the well-known topological limitations of this method can be overcome by an embedding into a pseudo-arclength continuation and prove that embedded time-delayed feedback control is able to stabilize periodic orbits that have at most one unstable Floquet multiplier sufficiently close to the unit circle. In the second part we introduce preconditioning into the time-delayed feedback control. In this way, we extract a nonlinear system of equations from time profiles, which we solve using Newton iterations.

We demonstrate the feasibility of our method by continuing periodic orbits in a laser model through folds, and by computing the family of canard orbits of the classical stiff Van der Pol system with constant forcing.
THE QUASI-PERIODIC REVERSIBLE HOPF BIFURCATION
Authors: BROER HENK W. , CIOCCI M. CRISTINA , HANßMANN HEINZ
Published: September 2007

We consider the perturbed quasi-periodic dynamics of a family of reversible systems with normally 1:1 resonant invariant tori. We focus on the generic quasi-periodic reversible Hopf bifurcation and address the persistence problem for integrable quasi-periodic tori near the bifurcation point. Using KAM theory, we describe how the resulting invariant tori of maximal and lower dimensions are parameterized by Cantor sets.
EVANS FUNCTIONS AND NONLINEAR STABILITY OF TRAVELING WAVES IN NEURONAL NETWORK MODELS
Authors: SANDSTEDE BJÖRN
Published: September 2007

Modeling networks of synaptically coupled neurons often leads to systems of integro-differential equations. Particularly interesting solutions in this context are traveling waves. We prove here that spectral stability of traveling waves implies their nonlinear stability in appropriate function spaces, and compare several recent Evans-function constructions that are useful tools when analyzing spectral stability.
ATTRACTORS OF FOURTH-ORDER CHUA'S CIRCUIT AND CHAOS CONTROL
Authors: LIU XIAN , WANG JINZHI , HUANG LIN
Published: September 2007

In this paper, in order to show some interesting phenomena of fourth-order Chua's circuit with a piecewise-linear nonlinearity and with a smooth cubic nonlinearity and compare dynamics between them, different kinds of attractors and corresponding Lyapunov exponent spectra of systems are presented, respectively. The frequency-domain condition for absolute stability of a class of nonlinear systems is transformed into linear matrix inequality (LMI) by using the celebrated Kalman–Yakubovich–Popov (KYP) lemma. A stabilizing controller based on LMI is designed so that chaos oscillations of fourth-order Chua's circuit with the piecewise-linear nonlinearity disappear and chaotic or hyperchaotic trajectories of the system are led to the origin. Simulation results are provided to demonstrate the effectiveness of the method.
ROBUST SYNCHRONIZATION CRITERIA FOR RECURRENT NEURAL NETWORKS VIA LINEAR FEEDBACK
Authors: HUANG XIA , LAM JAMES , CAO JINDE , XU SHENGYUAN
Published: September 2007

In this paper, the robust synchronization problem is addressed for recurrent neural networks with time-varying delay by linear feedback control. Robustness in the present paper is referred to as the allowance of parameters mismatch between the drive system and the response system. Sufficient conditions for robust synchronization with a synchronization error bound, expressed as linear matrix inequality (LMI), are derived based on Lyapunov–Krasovskii functionals. Both delay-dependent and delay-independent conditions are obtained. Two examples are given to illustrate the results.
EXPLICIT SOLUTIONS TO THE KAUP–KUPERSHMIDT EQUATION VIA NONLOCAL SYMMETRIES
Authors: REYES ENRIQUE G. , SANCHEZ GUILLERMO
Published: September 2007

The fifth order Kaup–Kupershmidt equation [Formula: see text] is a most important example of an integrable partial differential equation. Among other properties, it is integrable via scattering/inverse scattering techniques, it admits a bi-Hamiltonian formulation, and it possesses an infinite number of generalized symmetries. In sharp contrast with other integrable equations, however, it has proven very difficult to exhibit explicit solutions to Kaup–Kupershmidt. In this paper, we present several interesting particular solutions to this equation obtained with the help of nonlocal symmetries.
AMPLITUDE DEATH INDUCED BY A GLOBAL DYNAMIC COUPLING
Authors: KONISHI KEIJI
Published: September 2007

This paper presents a dynamic connection that can induce amplitude death in globally coupled oscillators. A linear analysis clarifies a local stability condition for global amplitude death. The analysis also indicates that the odd-number property, which is known in delayed feedback control, exists in global dynamic coupled oscillators. Furthermore, global amplitude death is experimentally observed in Chua's circuits coupled by an RC line.
PULSATING FEEDBACK CONTROL FOR STABILIZING UNSTABLE PERIODIC ORBITS IN A NONLINEAR OSCILLATOR WITH A NONSYMMETRIC POTENTIAL
Authors: LITAK G. , ALI M. , SAHA L. M.
Published: September 2007

We examine a strange chaotic attractor and its unstable periodic orbits in case of one-degree of freedom nonlinear oscillator with nonsymmetric potential. We propose an efficient method of chaos control stabilizing these orbits by a pulsating feedback technique. Discrete set of pulses enable us to transfer the system from one periodic state to another.
THE FREE ALTERNATIVE SUPERALGEBRA ON ONE ODD GENERATOR
Authors: SHESTAKOV IVAN , ZHUKAVETS NATALIA
Published: September 2007

A base of the free alternative superalgebra on one odd generator is constructed. As a corollary, a base of the alternative Grassmann algebra is given. We also find a new element of degree 5 from the radical of the free alternative algebra of countable rank.
AUTOMORPHISMS OF THE ENDOMORPHISM SEMIGROUP OF A FREE ASSOCIATIVE ALGEBRA
Authors: BELOV-KANEL A. , BERZINS A. , LIPYANSKI R.
Published: September 2007

Let [Formula: see text] be the variety of associative algebras over a field K and A = K 〈x1,…, xn〉 be a free associative algebra in the variety [Formula: see text] freely generated by a set X = {x1,…, xn}, End A the semigroup of endomorphisms of A, and Aut End A the group of automorphisms of the semigroup End A. We prove that the group Aut End A is generated by semi-inner and mirror automorphisms of End A. A similar result is obtained for the automorphism group Aut [Formula: see text], where [Formula: see text] is the subcategory of finitely generated free algebras of the variety [Formula: see text]. The later result solves Problem 3.9 formulated in [17].
SOME GROUP THEORY PROBLEMS
Authors: SAPIR MARK V.
Published: September 2007

This is a survey of some problems in geometric group theory that I find interesting. The problems are from different areas of group theory. Each section is devoted to problems in one area. It contains an introduction where I give some necessary definitions and motivations, problems and some discussions of them. For each problem, I try to mention the author. If the author is not given, the problem, to the best of my knowledge, was formulated by me first.
LINEAR GROUPS OVER LOCALLY FINITE EXTENSIONS OF INFINITE FIELDS
Authors: BASHKIROV E. L. , GUPTA C. K.
Published: September 2007

Let P be a field of characteristic different from 2, let K be an associative commutative P-algebra with an identity 1 and let n be an integer, n ≥ 2. Assume that K is an algebraic extension of P having, in general, zero divisors and P is an algebraic separable extension of an infinite subfield k. The paper studies subgroups X of the group GLn (K) such that X contains a root k-subgroup, i.e. a subgroup which is conjugate in GLn (K) to a group of all matrices [Formula: see text], a ∈ k.
MARKOV AND ARTIN NORMAL FORM THEOREM FOR BRAID GROUPS
Authors: BOKUT L. A. , CHAYNIKOV V. V. , SHUM K. P.
Published: September 2007

In this paper we will present the results of Artin–Markov on braid groups by using the Gröbner–Shirshov basis. As a consequence we can reobtain the normal form of Artin–Markov–Ivanovsky as an easy corollary.
ON AUTOMORPHISMS OF THE ENDOMORPHISM SEMIGROUP OF A FREE UNIVERSAL ALGEBRA
Authors: MASHEVITZKY G. , PLOTKIN B. I.
Published: September 2007

Let U be a universal algebra. An automorphism α of the endomorphism semigroup of U defined by α(φ) = sφs-1for a bijection s : U → U is called a quasi-inner automorphism. We characterize bijections on U defining such automorphisms. For this purpose, we introduce the notion of a pre-automorphism of U. In the case when U is a free universal algebra, the pre-automorphisms are precisely the well-known weak automorphisms of U. We also provide different characterizations of quasi-inner automorphisms of endomorphism semigroups of free universal algebras and reveal their structure. We apply obtained results for describing the structure of groups of automorphisms of categories of free universal algebras, isomorphisms between semigroups of endomorphisms of free universal algebras, automorphism groups of endomorphism semigroups of free Lie algebras etc.
AN A3-PROOF OF STRUCTURE THEOREMS FOR CHEVALLEY GROUPS OF TYPES E6 AND E7
Authors: VAVILOV NIKOLAI
Published: September 2007

In the nineties the author, A. Stepanov and E. Plotkin developed a geometric approach towards calculations in exceptional groups at the level of K 1, decomposition of unipotents. However, it relied on the presence of large classical embeddings, such as A 5 ≤ E 6 or A 7 ≤ E 7. Recently the author, M. Gavrilovich and S. Nikolenko devised a sharper geometric method which only uses embeddings A 2 ≤ E 6, E 7, F 4. Here we show that one can make a further step and simultaneously stabilize two columns of a root unipotent by an element of type A 3 ≤ E 6, E 7. This opens the way to applications of this method at the level of K 2.
THE STRUCTURE OF MUTUALLY PERMUTABLE PRODUCTS OF FINITE NILPOTENT GROUPS
Authors: BALLESTER-BOLINCHES A. , BEIDLEMAN J. , COSSEY JOHN , HEINEKEN H.
Published: September 2007

We consider mutually permutable products G = AB of two nilpotent groups. The structure of the Sylow p-subgroups of its nilpotent residual is described.
ON A FREIHEITSSATZ FOR CYCLIC PRESENTATIONS
Authors: JUHÁSZ ARYE
Published: September 2007

In this paper we examine the embeddability of a certain one-relator group in a cyclically presented group, which is naturally associated to it, as a function of a certain subgroup of the one-relator group. We find that if this subgroup is largest possible then it is rare that embedding occurs. On the other hand, when this subgroup is smallest possible, then embedding is very likely.
ON GEOMETRICALLY EQUIVALENT S-ACTS
Authors: KATSOV YEFIM
Published: September 2007

In this paper, considering the geometric equivalence for algebras of a variety [Formula: see text] of S-acts over a monoid S, we obtain representation theorems describing all types of the equivalence classes of geometrically equivalent S-acts of varieties [Formula: see text] over groups S.
A NOTE ON ALGEBRAIC LIMIT OF A REAL FUNCTION
Authors: LIVCHAK J.
Published: September 2007

A new viewpoint on the notion of the limit of a function is proposed. We define a series of algebraic limit transitions of a function and prove that every real function has a number of non-trivial algebraic limits.
ON FINITELY GENERATED SOLUBLE NON-HOPFIAN GROUPS, AN APPLICATION TO A PROBLEM OF NEUMANN
Authors: MIKAELIAN VAHAGN H.
Published: September 2007

Using methods of embeddings of groups, we prove that there is a continuum of soluble non-metanilpotent varieties which contain 3-generator non-Hopfian groups and non-countably many pairwise non-isomorphic finitely generated groups. This provides us with broad sets of groups for which a problem of Neumann has positive answer.
THE EQUATION [x,u] + [y,v] = 0 IN FREE LIE ALGEBRAS
Authors: REMESLENNIKOV VLADIMIR , STÖHR RALPH
Published: September 2007

We investigate equations of the form [x,u] + [y,v] = 0 over a free Lie algebra L. In the case where u and v are free generators of L, we exhibit two series of solutions, we work out the dimensions of the homogeneous components of the solution space, and we determine its radical. In the general case we show that the results on free generator coefficients are sufficient to obtain the solution space up to finite codimension. As an application we determine the radical of the bilinear equation [x1,x2] + [x3,x4] = 0.
TAME AUTOMORPHISMS FIXING A VARIABLE OF FREE ASSOCIATIVE ALGEBRAS OF RANK THREE
Authors: DRENSKY VESSELIN , YU JIE-TAI
Published: September 2007

We study automorphisms of the free associative algebra K〈x,y,z〉 over a field K which fix the variable z. We describe the structure of the group of z-tame automorphisms and derive algorithms which recognize z-tame automorphisms and z-tame coordinates.
AUTOMORPHISMS OF THE CATEGORY OF THE FREE NILPOTENT GROUPS OF THE FIXED CLASS OF NILPOTENCY
Authors: TSURKOV A.
Published: September 2007

This paper is motivated by the following question arising in universal algebraic geometry: when do two algebras have the same geometry? This question requires considering algebras in a variety Θ and the category Θ0of all finitely generated free algebras in Θ. The key problem is to study how far the group Aut Θ0of all automorphisms of the category Θ0is from the group Inn Θ0of inner automorphisms of Θ0(see [7, 10] for details). Recall that an automorphism ϒ of a category 𝔎 is inner, if it is isomorphic as a functor to the identity automorphism of the category 𝔎.

Let Θ = 𝔑dbe the variety of all nilpotent groups whose nilpotency class is ≤ d. Using the method of verbal operations developed in [8, 9], we prove that every automorphism of the category [Formula: see text], d ≥ 2 is inner.
A MATHEMATICAL MODEL OF IMMUNE RESPONSE IN CUTANEOUS LEISHMANIASIS
Authors: DE ALMEIDA MARCOS C. , MOREIRA HELMAR N.
Published: September 2007

The TH1/TH2 paradigm has been largely used in the interpretation of several diseases, particularly in leishmaniasis. As far as we know there is no mathematical description of this model related to leishmaniasis. We have extended and modified a previous published set of equations1in order to adapt it to leishmanial disease particularities. The main modifications were: (1) the analysis of logistic and exponential parasite growth curves, (2) the assumption of the TH2 arm of the immune response having a positive action on parasite growth. The set of three simultaneous differential equations describing the TH1 arm, TH2 arm and parasite growth were analyzed for conditions of existence and stability of the solutions.

Stable solutions valid for the logistic and exponential parasite growth models, with its possible clinical correlations, were obtained in the following situations: (1) parasite and TH2 extinction [TH1 cure], (2) parasite extinction and TH1/TH2 co-existence [TH1/TH2 cure], (3) TH1 and parasite co-existence, TH2 extinction [stable TH1 infection], and (4) TH1, TH2 and parasite co-existence [stable TH1/TH2 infection]. TH2 and parasite co-existence associated to TH1 extinction [stable TH2 infection] was obtained only with the logistic growth model. The model also provides an alternative hypothesis for TH1 bias in resistant mice and emphazises the importance of natural immunity for the existence of chronic states.
PULSE FISHING POLICY FOR A STAGE-STRUCTURED MODEL WITH STATE-DEPENDENT HARVESTING
Authors: JIAO JIANJUN , CHEN LANSUN , LONG WEN
Published: September 2007

The reports of the Second International Symposium on Cage of Aquaculture in Asia (SISCAA) show that much attention is being paid to resource management. It is important to solve this remarkable problem. In this work, a state-dependent impulsive differential model focusing on a stage structure and impulsive harvest aims for the simulation of the factual biological resource management. With the approaches of continuity of function rule, we obtain the sufficient conditions of the existence and orbitally asymptotic stability of periodic solution. Our results are valuable for biological resource management in practice.
SYMMETRY WITH THE PINUS MUGO TURRA — AN ECOLOGICAL APPROACH
Authors: VAKARELOV ILIYA IVANOV
Published: September 2007

The study focuses on two aspects of the symmetry in plants. The first one concerns the morphology of pine leaves, which could be, from the point of view of symmetry, left (L), right (D) and symmetrical (S). The second one concerns phyllotaxis, perceived as an arrangement of structures. Subject of analysis are the changes in the stereomorphism of leaves, occurring in population of Pinus mugo in relation to the changes in altitude and solar activity. The results revealed that these changes express cyclical patterns. Also, some characteristics of the phyllotaxis in twigs of P. mugo were analyzed in relation to the changes in ecological conditions in different years and altitudes. The changes in the phyllotaxis express cyclical patterns too. It is concluded that the changes in the stereomorphism of leaves and in the structure of phyllotaxis in P. mugo are ecologically determined.
ON A PERIODIC TIME-DEPENDENT IMPULSIVE SYSTEM OF STRATEGIES FOR CONTROLLING THE APPLE SNAIL IN PADDY FIELDS
Authors: ZHANG HONG , ZHU RONGPING , CHEN LANSUN
Published: September 2007

This paper deals with a periodic coefficients predator-prey system with impulsive harvesting for the predator, in which the prey has a history that takes them through two stages, juvenile and adult. We apply this system to model strategies for controlling apple snails which are serious pests of young rice seedlings in paddy fields. A sufficient and necessary condition to guarantee permanence of the system is provided. Finally, we give a brief discussion of our result.
Inherited Mitochondrial Diseases of DNA Replication
Authors: Copeland William C.
Published: September 2007

Mitochondrial genetic diseases can result from defects in mitochondrial DNA (mtDNA) in the form of deletions, point mutations, or depletion, which ultimately cause loss of oxidative phosphorylation. These mutations may be spontaneous, maternally inherited, or a result of inherited nuclear defects in genes that maintain mtDNA. This review focuses on our current understanding of nuclear gene mutations that produce mtDNA alterations and cause mitochondrial depletion syndrome (MDS), progressive external ophthalmoplegia (PEO), ataxia-neuropathy, or mitochondrial neurogastrointestinal encephalomyopathy (MNGIE). To date, all of these etiologic nuclear genes fall into one of two categories: genes whose products function directly at the mtDNA replication fork, such as POLG, POLG2, and TWINKLE, or genes whose products supply the mitochondria with deoxynucleotide triphosphate pools needed for DNA replication, such as TK2, DGUOK, TP, SUCLA2, ANT1, and possibly the newly identified MPV17.
Antiretroviral Drug–Based Microbicides to Prevent HIV-1 Sexual Transmission
Authors: Klasse Per Johan , Shattock Robin , Moore John P.
Published: September 2007

The development of a vaginal (and perhaps a rectal) microbicide would be of major benefit for slowing the global spread of human immunodeficiency virus type 1 (HIV-1). A microbicide is a gel or related device that, when inserted vaginally or rectally, acts to prevent infection of a woman or a man by HIV-1 during sexual intercourse. A practical microbicide must be not only effective, safe, and user-friendly but also economically affordable in the developing world. To date, the performance of microbicide candidates in efficacy trials has been disappointing, but next-generation concepts now in or approaching clinical trials offer improved prospects for efficacy. The most plausible approaches involve topical application of antiretroviral agents with specific activity against HIV-1, compounds similar to drugs used to treat HIV-1 infection. How these inhibitors are applied may also be critical, with sustained-release formulations and vaginal ring delivery systems now becoming a high priority.
Large-Scale Sensor Networks Simulation with GTSNetS
Authors: Ould-Ahmed-Vall El Moustapha , Riley George F. , Heck Bonnie S.
Published: September 2007

This paper presents a highly scalable sensor network simulation environment that allows users to evaluate the effects of different architectural choices and strategies on the lifetime and performance of a sensor network. This tool can also be used to evaluate new approaches (e.g., routing protocols, cooperation algorithms), and compare them with the ones already in place. The simulator incorporates models for the different functional units composing a sensor node and characterizes the energy consumption of each. GTSNetS is designed in a modular and efficient way favoring the ease of use and extension. The simulator also allows the user to choose from different implementations of energy models, accuracy models, communication protocols, application classes and types of sensors. New models can be easily added if necessary. Simulation results from a set of tests are reported to demonstrate some of the capabilities of the simulator. We present a case study using our tool to measure the performance of an existing algorithm that provides fault-tolerance for distributed detection using a wireless sensor network. The simulator gives results that are in accordance with the ones reported in the original paper describing the simulated algorithm. Tests were also performed to evaluate the simulator scalability as the network size increases. In particular, it was found that this tool could simulate sensor networks of several hundred thousand nodes while using less than 2 GB of memory, which exceeds the capabilities of existing simulators by an order of magnitude. The simulation execution time also scales well with the network size.
Localized Route Selection for Traffic with Bandwidth Guarantees
Authors: Alabbad Saad H. , Woodward Michael E.
Published: September 2007

Localized Quality of Service (QoS) routing has recently been proposed as a viable alternative approach to traditional QoS routing algorithms that use global state information. In this approach, problems associated with maintaining global state information are avoided by having the source nodes to infer the network QoS state based on flow blocking statistics collected locally, and perform flow routing using this localized view of the network QoS state. One of the most important QoS metrics is bandwidth and in this paper we introduce a localized routing scheme for providing bandwidth guarantees, based on a crediting scheme that uses an estimate of flow blocking probability to adjust credits and select routes. We compare its performance against the localized proportional sticky routing (PSR) algorithm using different types of network topologies, QoS requirements and traffic patterns and under a wide range of traffic loads. Extensive simulations show that our algorithm outperforms the PSR scheme while maintaining the same level of adaptivity and stability. We also compare performance against the well known widest-shortest path (WSP) algorithm that uses the global network QoS state and show that our algorithm gives a comparable performance with better time complexity and very much lower communication overhead. The simulations were implemented using OMNET ++, a discrete-event simulator that provides a rich set of functions and tools for simulating the elements of a communication network, such as nodes, links and packets.
Wavelet-based Neighborhood Control for Self-Sizing Networks
Authors: Nalatwad Srikant , Devetsikiotis Michael
Published: September 2007

The exponential growth of the Internet has turned it into a multiservice complex network of heterogeneous elements with dynamically changing traffic conditions. To regulate such a large scale network it is necessary to place intelligence in the nodes and find simple distributed rules and strategies that can produce meaningful and consistent behavior. These control mechanisms must be adaptive to effectively respond to continually changing network conditions. A “self-sizing” network can allocate link/switch capacity automatically and adaptively using online traffic data. Such adaptive, distributed, localized mechanisms are crucial to provide a scalable solution for controlling large, complex networks. In this paper, we propose a new, distributed self-sizing framework for locally controlled networks, which can support the stringent requirements of real-time applications in the Internet. Our unified and critical study of online resource allocation algorithms of two different classical approaches, led us to the use of adaptive multi-resolution decomposition (“wavelet”) algorithms. Our results show that by performing online resource allocation at each node based on their local knowledge, we can achieve considerable bandwidth savings and also satisfy QoS at the packet level. In our novel “neighborhood control” technique, we establish that by increasing the knowledge of some nodes so that higher self-sizing gains can be attained.
The Marriage Revolution in Late Antiquity: The Theodosian Code and Later Roman Marriage Law
Authors: Kuefler Mathew
Published: September 2007

Although much scholarly work has already been done on Roman marriage law, most of it deals with the classical era, and little has been done to explore the remarkably radical changes to marriage law in Roman law in late antiquity, that is, during the fourth and fifth centuries C.E. The Theodosian Code provides a unique and valuable source of information, despite the limitations evident in any legal text, on a wide range of legal issues pertaining to marriage: the necessity of marriage, the choice of marriage partner and consent to marriage, marriage payments, adultery and divorce, remarriage and inheritance, and even the marriages of slaves, soldiers, and clerics, and same-sex marriage. The extent of the changes revealed even demands new questions about the influence of Christian ideology on later Roman law.
The Informalization of the Parent-Child Relationship: An Investigation of Parenting Discourses Produced in Australia in the Inter-War Years
Authors: Kitchens Rachael
Published: September 2007

Drawing on the work of Norbert Elias, this article will explore the informalization of the parent-child relationship as reflected in parenting literature produced in Australia in the inter-war years. Authors of this literature have placed limits on the use of violence, discourage authoritarian disciplinary methods, and promote children's independence and autonomy. It is the contention of this article that these attempts to transform child-rearing practices can be interpreted as part of what Elias called the “civilizing process,” by which a greater capacity for self-control is exacted on the part of both children and parents. It will also be argued that Elias's framework offers an alternative approach to Marxist and Foucaultian perspectives that place emphasis on social control.
“Children of Adversity”: Disabilities and Child Welfare in Canada from the Nineteenth to the Twenty-First Century
Authors: Strong-Boag Veronica
Published: September 2007

The needs of particularly vulnerable children and youth have long tested Canadian parents and communities. Youngsters with mental and physical impairments have historically experienced a wide range of conditions that are always negotiated in the context of cultural assumptions, existing social supports and barriers, and available technologies. Both institutionalization and inadequate domestic substitutes have a long history, like birth families everywhere, of devastating youngsters beyond their original impairments. The construction of that predicament and its relationship to the use of institutions, fostering, and adoption in Canadian child welfare practices is the concern here. This article begins with a review of the commonplace evaluation of disabled youngsters in English-speaking Canada, next considers the vulnerability of families, and turns finally to institutional and domestic alternatives to birth family care. Although the story in each case is mixed, youngsters with disabilities remained vulnerable into the twenty-first century.
Strangers in the Family: Work, Gender, and the Origins of Old Age Homes
Authors: Christie Nancy
Published: September 2007

Through an examination of nineteenth-century familial correspondence and the records of various Protestant charitable organizations in Quebec City and Montreal, this article explores the changing culture of family care during illness and old age. It posits a new interpretation for the foundation of asylums for women that emphasizes changing perceptions of the family, especially the attitudes regarding the care of servants within the household. Furthermore, it argues that the treatment of servants as both caregivers and those in need of medical care is an important yardstick by which to measure the waning of the patriarchal household and the emergence of more explicitly contractual relations between the classes.
The Influence of Modern City Life on Marriage in Ghent at the Turn of the Twentieth Century: Cultural Struggle and Social Differentiation in Demographic Behavior
Authors: Van de Putte Bart
Published: September 2007

At the turn of the twentieth century, Ghent became a modern industrial city. The new societal conditions undermined old behavioral patterns. In a process of cultural interaction based on strategies of distinction, disciplining, conformism, and trendsetting, the elite, the middle class, and the lower class adopted a new marriage pattern. Social differentiation, however, remained strong. First, strong group boundaries on the marriage market, between the lower class on one side and the middle class and the elite on the other, were complemented by intensified distinction strategies by the elite and the middle class, as is shown in both their selection of marriage witnesses and their use of French. Second, in all groups, a decline in the mean age at marriage and an increasing proportion of same-age marriages marked the rise of more egalitarian relationships and the increasing importance of marriage as a source of respectability. This development did not, however, reduce the clear differences among the social groups, with the elite and middle class showing a less egalitarian pattern.
Women and Watershed Development in India
Authors: Arya Swarn Lata
Published: September 2007

A paradigm shift in soil and water conservation measures from an isolated approach to integrated watershed development programmes (WDPs) in the early 1970s em-phasised the active involvement or sense of ownership of the farming community for economic and social uplift on a holistic basis, particularly of the weaker sections and women. Guidelines issued by the Government of India have overlooked the divergent needs and interests that rural women have in relation to land and water. Women's participation has always been under a kind of ‘reservation policy’ and not as a matter of right. The soil and water conservation measures undertaken have failed to take into consideration the imbalance between men and women's ownership rights, division of labour and income. Women's participation in watershed development projects should not merely be judged by the number of women working as labour or by their ‘proxy presence’ in meetings, but by making them an integral part in the decision-making process and sense of belongingness in the development programmes.
Internet Equaliser? Gender Stratification and Normative Circumvention in Science
Authors: Palackal Antony , Anderson Meredith , Miller B. Paige , Shrum Wesley
Published: September 2007

Gender and connectivity initiatives intended to promote development assume that the Internet can have a significant impact on the careers and lives of women. It is important to test this assumption, given the prior research that establishes the educational and organisational limitations on women in professional careers, which increase the likelihood of restricted networks. The initial quantitative research available on the impact of the Internet is based on data from 2000. It shows improved access to the Internet for both men and women, but no evidence for Internet effects on productivity or professional networking. This study employs recent qualitative data from scientists in Kerala, which modify these conclusions and provide some grounds for optimism. The domestic context, so important for women in a patrifocal society, has created conditions for change, as the interest in children's education and the presence of home computers has begun a process of ‘circumvention’ of gender roles that demands further study.
Perceiving and Producing Merit
Authors: Subramanian Jayasree
Published: September 2007

This article documents the experiences of women scientists in research institutions in India, and attempts to demonstrate that contrary to the claims made by the institutions in deciding who gets to do science, gender figures at various levels in shaping the career of a scientist. Using the narratives of women scientists, structured interviews and the data collected from research institutions, this article attempts to problematise the notion prevalent among scientists that talent for doing science is inherent in a person, and if it is there it will reveal itself irrespective of the external conditions. The article tries to argue that such a notion and the resultant practice leads to selecting a few as meritorious and deserving, who are further nurtured, while others are expected to prove themselves many times before opportunities are made available for them. Women rarely figure among the meritorious few. In order that women get equal opportunity to participate in the scientific endeavour, the structure and organisations of science institutions must be transparent, democratic in their approach, and rethink the narrow definition of ‘merit’ that is currently operative.