bluuebunny/crossref_metadata_2025 huggingface dataset:
Flower Mites of Calyptrogyne ghiesbreghtiana (Arecaceae): Evidence for Dispersal Using Pollinating Bats1
Authors: Tschapka Marco , Cunningham Saul A.
Published: March 2006

We describe the association between a new species of flower mite (tribe Melicharini) and Neotropical flower‐visiting bats. Analogous to the well‐known hummingbird‐mite interactions, these mites appear to use bat visitors of the lowland tropical palm Calyptrogyne ghiesbreghtiana as a means of traveling to new inflorescences. Phenology data show tight coupling between the occurrence of mites on bats and flowering phenology of C. ghiesbreghtiana, suggesting that the palm is the most important host for the mites.

Describimos la asociación entre una nueva especie de ácaro de las flores (tribu Melicharini) y murciélagos Neotropicales que visitan flores. Similar a la interacción bien conocida entre colibries y ácaros, aparentemente estos ácaros utilizan a los murciélagos que visitan las inflorescencias de la palma Calyptrogyne ghiesbreghtiana como medio de transporte hacia nuevas inflorescencias. Datos de fenologia indican una fuerte asociacion entre los registros de los ácaros en los murciélagos y la fenologia floral de C. ghiesbreghtiana, sugierendo que la palma es el hospedero más importante para los ácaros.
Population Dynamics of a Resident Colony ofLeptonycteris curasoae(Chiroptera: Phyllostomidae) in Central México
Authors: Galindo G. Cristobal , Sánchez Q. Adalinda , Quijano Ramón H. , Herrera M. L. Gerardo
Published: March 2006

We studied the population dynamics of the lesser long–nosed batLeptonycteris curasoaein a cave in central Mexico for a two‐year time. The population had substantial seasonal changes in size and composition during this time. Colony size was largest from February to July (22,000–27,000 adults) and contained equal numbers of males and females. In June and July, males had enlarged testes and presumably mated with females. In August, the population size began to decline and was mostly composed of pregnant females. Between September and December, the colony was composed exclusively of pregnant and lactating females and their young, and population size decreased to about one–third of the observed maximum size. In January, adult males returned to the roost and the population size increased. We also observed an increase in body mass and fat accumulation in both sexes, apparently related to reproductive activity. This is the first report of the continuous presence of a substantial female population ofL. curasoaethroughout the year in a single roost in Mexican tropics, indicating that some populations ofL curasoaein central Mexico complete their life cycle without having to migrate.

Se estudió la dinámica poblacional del murciélago nectarivoroLeptonycteris curasoaeen una cueva localizada en el centro de México durante dos años. La población presentó cambios sustanciales en su tamaño y composición durante este periodo. El tamaño más grande de la población se registró entre febrero y julio (22,000–27,000 individuos) con una proporción similar de hembras y machos. En junio y Julio los testfculos de los machos crecieron y aparentemente se aparearon con las hembras. En agosto, la población empezó a disminuir y se encontraron casi exclusivamente hembras preñadaz. Entre septiembre y diciembre, la colonia estuvo compuesta exclusãvamente de hembras preñadaz o lactantes y de sus cri'as. La población disminuyó en este periodo hasta equivaler a una tercera pane del tamaño máximo registrado en el año. En enero, la población empezo a crecer de nuevo con la incorporación de machos adultos. Durante el ano, en ambos sexos se observaron también cambios en la masa corporal y en la acumulación de grasa aparentemente relacionados con la actividad reproductiva. Este es el primer estudio que reporta la presencia continua de hembras en una colonia deL. curasoaeen la misma cueva durante todo el ano para el centro de México. Nuestros resultados indican que esta población no es migratoria a diferencia de otras poblaciones de esta especie.
Predation‐mediated Mortality of Early Life Stages: A Field Experiment with Nymphs of an Herbivorous Stick Insect (Metriophasma diocles)
Authors: Berger Jürgen R. , Wirth Rainer
Published: March 2006

We quantified predation pressure on first instar nymphs of a stick insect in predator‐exclusion experiments in the forest of Barro Colorado Island, Panamá. After considering intrinsic mortality (19%) and potential emigration (negligible), we estimated that 54 percent of the nymphs died due to predation in a two‐week period. Predation on nymphs was highest at night and may explain the low abundance of Metriophasma diodes in the understory.
The Role of Canopy Ants in Removing Ficus perforate Seeds from Howler Monkey (Alouatta palliata mexicana) Feces at Los Tuxtlas, México
Authors: Martinez‐Mota Rodolfo , Serio‐Silva Juan Carlos , Rico‐Gray Victor
Published: March 2006

We analyzed Ficus perforate seed removal by canopy ants under four treatments: syconia seeds; howler monkey‐defecated washed seeds; syconia seeds with howler dung; and defecated seeds with howler dung. Ants removed more defecated washed seeds in the wet season, while during the dry season, removal was greater for syconia seeds and defecated washed seeds. Our results suggest that ants tended to remove more seeds when they were not embedded in feces; however, even seeds set on howler dung were still attractive to ants.

Determinamos la preferencia de hormigas para remover semillas de Ficus perforata bajo cuatro tratamientos: semillas provenientes de siconos y semillas defecadas por monos aulladores; y dentro de cada uno de estos tipos se colocaron semillas sobre heces frescas. Las hormigas removieron más semillas defecadas en la estación húmeda, mientras que en la estación seca la mayor remoción fue para las semillas de siconos y semillas defecadas. Los resultados sugieren que las hormigas remueven más semillas cuando no están embebidas en excretas, sin embargo también las semillas colocadas en excretas fueron atractivas para las hormigas.
Spatial Distribution Patterns of Jumping Spiders Associated with Terrestrial Bromeliads
Authors: Romero Gustavo Q. , Vasconcellos‐Neto Joäo
Published: March 2006

The jumping spiders Eustiromastix native, Psecas sumptuosus, and Uspachus sp. n. (Salticidae) live on terrestrial bro‐meliads in areas with different phytophysiognomies in southeastern and northeastern Brazil. To understand these spider–plant interactions, we investigated if (1) these spiders were associated specifically with bromeliads, (2) the spiders utilized particular bromeliad species, and (3) plant size and density of bromeliads affected spider distribution. The jumping spiders were not found outside bromeliads, indicating a strict spider–plant association. Eustiromastix and Uspachus occupied bromeliads in open areas, whereas Psecas was found on forest bromeliads. Eustiromastix occurred at a higher frequency on larger bromeliads and in patches with higher bromeliad density. This is one of the few studies to demonstrate specific relationships between jumping spiders and a particular plant type.

As aranhas saltadoras Eustiromastix native, Psecas sumptuosus e Uspachus sp. n. (Salticidae) vivem sobre bromélias terrestres em áreas com diferentes fitofisionomias no sudeste e nordeste do Brasil. Para compreender estas interaçóes aranha‐planta, nós investigamos se (1) estas aranhas estavam associadas especificamente a bromélias, (2) as aranhas utilizam espécies particulares de bromélias e (3) tamanho e densidade das bromélias afetam a distribuiçáo das aranhas. As aranhas saltadoras não foram encontradas fora das bromélias, indicando uma associaçáo estrita entre aranha e planta. Eustiromastix e Uspachus ocuparam bromelias em areas abertas enquanto Psecas foi encontrada em bromélias de floresta. Eustiromastix ocorreu em maior freqüéncia sobre bromélias maiores e em manchas com maior densidade de bromélias. Este estudo é um dos poucos a demonstrar relaço̧es especificas entre aranhas saltadoras e um tipo particular de planta.
Forest Modification Affects Diversity (But Not Dynamics) of Speciose Tropical Pyraloid Moth Communities
Authors: Fiedler Konrad , Schulze Christian H.
Published: March 2006

We studied temporal and spatial dynamics of extremely diverse moth ensembles (Lepidoptera: Pyraloidea) along a gradient of forest disturbance ranging from undisturbed primary tropical rain forest to different kinds of modified forest and open cultivated land at the margin of Mount Kinabalu National Park (Sabah, East Malaysia). We sampled moths by light trapping during two periods (March‐May and August‐September 1997). We collected a total of 7724 individuals representing 680 species during 78 light‐trapping nights at six study sites. Species diversity (Fisher's α) of ensembles in undisturbed primary forest was distinctly higher than in disturbed or secondary forest. More pyraloid moths were attracted in undisturbed primary forest. Samples from disturbed primary or old‐growth secondary forest were statistically indistinguishable from the undisturbed primary forest ensemble in regard to species composition. Thus, pyraloid ensembles from disturbed forest with tall trees remaining appeared to represent impoverished subsets of the undisturbed primary forest community. The more heavily disturbed sites had a distinct fauna and showed a stronger faunal differentiation among each other. Four species of the genus Eoophyla, in which aquatic larvae feed on algae in fast‐running streams benefited prominently from forest disturbance. Temporal variation of ensembles was remarkably concordant across the disturbance gradient. Relative abundance variation of the commonest species was identical at all sites. Overall, pyraloid moths responded more sensitively to anthropogenic habitat alteration than most other moth taxa studied thus far in tropical regions and allowed for an analysis of diversity patterns at a high temporal resolution.
Do Species Dominance Indices Indicate Rain Forest Disturbance by Logging?
Authors: Nurnrnelin Matti , Kaitala Seppo
Published: March 2006

Species distributions of several insect groups in unlogged and adjacent logged forest were analyzed from several published data sets. The slope of the geometric series model and dominance indices proved to be unsuitable indicators of rain forest disturbance.

De un conjunto de datos publicados, se analizó la distribución de varias especies de grupos de insectos en un bosque sin deforestar y adjacente a un bosque deforestado. La pendiente del modelo de serie geom.étrico y los indices de dominación probaron ser indicadores no adecuados de perturbaciones del bosque lluvioso.
The Azteca‐Cecropia Association: Are Ants Always Necessary for Their Host Plants?
Authors: Fáveri Sarita B. , Vasconcelos Heraldo L.
Published: March 2006

We assessed the effects of Azteca alfari presence on herbivory and growth of saplings for two Amazonian Cecropia species. For both species, rates of herbivory were low and did not differ between ant‐removed and ant‐maintained plants. Plant growth, measured over six months, was also similar among treatments. This is the first experiment to show that in its native mainland habitat, Cecropia may suffer low incidence of attack by insect herbivores in the absence of associated ants.

Nós testamos os efeitos da presença de Azteca alfari sobre a herbivoria e crescimento em arvoretas de duas espécies de Cecropia, na Amazo̧nia. Para ambas espécies, as taxas de herbivoria foram baixas e não diferiram entre plantas que tiveram as formigas removidas ou mantidas. O crescimento das plantas, medido após seis meses, também foi similar entre os tratamentos. Este é o primeiro experimento que mostra que em seu hábitat natural, Cecropia pode sofrer baixa incidȩncia de ataque por herbivoros na ausȩncia das formigas associadas.
Employee development, commitment and intention to turnover: a test of ‘employability’ policies in action
Authors: Benson George S.
Published: March 2006

Participation in three types of development activities is examined among salaried employees of a firm that significantly increased access to development after a series of layoffs in the late 1990s. Analyses of survey and archival data representing 667 employees show that on‐the‐job training was positively related to organisational commitment and negatively related to intention to turnover. Participation in tuition‐reimbursement, which provides more general or marketable skills, was positively related to intention to turnover. However, intention to turnover was reduced after earning a degree through tuition‐reimbursement if employees were subsequently promoted. Implications for an employment relationship based on ‘employability’ are discussed.
Multiscale Thermodynamic Significance of the Scale Invariance Approach in Continuum Inelasticity
Authors: Yang Q. , Chen X. , Zhou W. Y.
Published: March 2006

In this paper, the scale invariance approach from micro- to macro-plasticity by Aifantis (1995, “From Micro- to Macro-plasticity: The Scale Invariance Approach,” ASME J. Eng. Mater., 117, pp. 352–355) and Ning and Aifantis (1996, “Anisotropic Yield and Plastic Flow of Polycristalline Solids,” Int. J. Plasticity, 12, pp. 1221–1240) is investigated within Rice’s normality structure (1971, “Inelastic Constitutive Relations for Solids: An Integral Variable Theory and its Application to Metal Plasticity,” J. Mech. Phys. Solids, 19, pp. 433–455; 1975, “Continuum Mechanics and Thermodynamics of Plasticity in Relation to Microscale Deformation Mechanisms,” Constitutive Equations in Plasticity, A. S. Argon, ed., MIT Press, Cambridge, MA, pp. 23–79). The normality structure provides a minimal framework of multiscale thermodynamics, and the dissipation equivalence between the microscale and macroscale is ensured by a variational equation which can be further formulated into principle of maximum equivalent dissipation. It is revealed in this paper that within the framework of normality structure, the so-called hypothesis of generalized scale invariance holds for the kinetic rate laws, flow rules, and orthogonality conditions in the sense of Aifantis (1995, “From Micro- to Macro-plasticity: The Scale Invariance Approach”). Stemming from Rice’s kinetic rate laws, the generalized scale invariance reflects the inherent self-consistent character of the normality structure. If the plastic work rate is assumed to be equal to the intrinsic dissipation rate, the kinematic hardening plasticity as a demonstration of the scale invariance approach by Aifantis (1995, “From Micro- to Macro-plasticity: The Scale Invariance Approach”), can be well accommodated within the framework of normality structure. Therefore, the scale invariance approach is justified from a multiscale thermodynamic viewpoint. It is further shown that the maximization procedure in this approach just corresponds to the principle of maximum equivalent dissipation.
Effect of Oxygen Content on the Processing Maps for Hot Deformation of OFHC Copper
Authors: Prasad Y. V. R. K. , Rao K. P.
Published: March 2006

Processing map for the hot deformation of high purity oxygen free high conductivity (OFHC) copper (2ppm oxygen) has been developed in the temperature range 600-950°C and strain rate range 0.001-100s−1. The map is compared with those published earlier on OFHC copper with higher oxygen contents (11ppm and 30ppm) with a view to evaluating the effect of oxygen content on the dynamic behavior of OFHC copper and the mechanism of hot deformation. The maps reveal that dynamic recrystallization (DRX) occurs over a wide temperature and strain rate range and is controlled by different diffusion mechanisms. In OFHC copper with 2ppm oxygen, the apparent activation energy for the DRX domain in the strain rate range 0.01-10s−1 and temperature range 600-900°C is estimated to be about 137kJ∕mole which suggests dislocation core diffusion to be the rate controlling mechanism. However, this domain is absent in the maps for OFHC copper with higher oxygen content due to the “clogging” of dislocation pipes by the oxygen atoms thereby preventing this short circuit diffusion process. At strain rates in the range 1-100s−1 and temperatures >700°C, the apparent activation energy is 73kJ∕mole suggesting that DRX is controlled by grain boundary self diffusion, and this domain expands with higher oxygen content in OFHC copper. At strain rates <0.01s−1 and temperatures >750°C, lattice self-diffusion is the rate controlling mechanism and this lower strain rate domain moves to lower temperatures with increasing oxygen content.
Magnetorheological Fluid Behavior Under Constant Shear Rates and High Magnetic Fields Over Long Time Periods
Authors: Ciocanel Constantin , Molyet Kevin , Yamamoto Hideki , Vieira Sheila L. , Naganathan Nagi G.
Published: March 2006

This paper presents a new magnetorheological (MR) cell design along with a study of the magnetic field, shear rate, and time/shear strain influences on the properties and behavior of a MR fluid tested for long periods of time. The MR cell was designed to adapt a commercially available rheometer to measure the rheological properties of the fluid. Overall characteristics of the designed MR cell output capability are provided. Constant shear rate tests, two hours in duration, have been performed at shear rates between 0.1l∕s and 200l∕s under magnetic field intensities up to 0.4T. The rheological measurements indicated that over time the fluid’s shear stress magnitude decreases until it reaches a steady state. The time required to reach the steady state depends on both the magnetic field strength and the shear rate. The higher the field and the smaller the shear rate the shorter the time for the steady state to be reached.
Size Effect on Compressive Strength of Sandwich Panels with Fracture of Woven Laminate Facesheet
Authors: Bayldon John , Bažant Zdeněk P. , Daniel Isaac M. , Yu Qiang
Published: March 2006

Prismatic sandwich specimens of various sizes, geometrically scaled in the ratio 1:2:4:8, are subjected to eccentric axial compression and tested to failure. The sandwich core consists of a closed-cell polyvinyl chloride foam, and the facesheets are woven glass-epoxy laminates, scaled by increasing the number of plies. The test results reveal a size effect on the mean nominal strength, which is strong enough to require consideration in design. The size effect observed is fitted with the size effect law of the energetic (deterministic) size effect theory. However, because of inevitable scatter and limited testing range, the precise form of the energetic size effect law to describe the test results is not unambiguous. The Weibull-type statistical size effect on the mean strength is ruled out because the specimens had small notches which caused the failure to occur in only one place in the specimen, and also because the observed failure mode was kink band propagation, previously shown to cause energetic size effect. Various fallacies in previous applications of Weibull theory to composites are also pointed out.
Identification of Small-Sized Cracks on Cross-Stiffened Plate Structures for Ships
Authors: Budipriyanto A. , Swamidas A. S. J. , Haddara M. R.
Published: March 2006

In this paper we discuss the results of experimental and numerical studies carried out for monitoring the integrity of a 1∕20th model of the side shell of a ship’s structure, using its vibration responses. The model was tested for different crack development scenarios under random exciting force having a dominant spectral frequency much lower (≈2Hz) than the first natural frequency of the structure (≈580Hz). Sensor locations were justified based on modal responses under intact and damaged conditions. A damage detection procedure using the root mean square response modal amplitudes is also presented.
Enhanced electromagnetic wave transmission through narrow conducting channels
Authors: Brand G. F.
Published: March 2006

The transmission of an electromagnetic wave through a thick conducting grating, where the conductors are separated by a small fraction of a wavelength, is examined. The conditions for which almost all of the incident radiation can pass through are found. This theoretical result is confirmed by a microwave experiment at 35GHz.
Effect of electrically insulating materials on magnetically induced electrical currents in a tissue-like medium
Authors: Hoffmeister Brent K. , Shores Andrew R. , Banerjee Shubho , Malkin Robert A.
Published: March 2006

Time varying magnetic fields can induce eddy currents in a conductor. Electrical currents also can be induced magnetically in the human body, and there has been considerable interest in the bioeffects of this phenomenon. We present an analytical model derived from Faraday’s law and Coulomb’s law that provides physical insight into how electrically insulating materials in a tissue-like medium redirect magnetically induced currents. The model shows that charge accumulates at the tissue-insulator interface to produce a secondary electric field. This field combines with the magnetically induced electric field to alter the net electric field in the vicinity of the insulator, causing the electric current to flow around the insulator. The model is supplemented by measurements of magnetically induced electric fields in a volume of physiologic saline solution. Good agreement is found among the model, the measurements, and a finite element analysis model of the experiment.
Quantitative electric field measurements in an intermediate laboratory
Authors: Thomas Bruce R.
Published: March 2006

We describe an apparatus that enables students to study the electric fields and the associated surface charges for several different electrode structures including parallel plates, cylindrical rods over plates, and nested cylinders. The study involves the relations among potential difference, electric field, surface charge density, and total charge. These relations are confirmed to within a few percent.
Teaching about circuits at the introductory level: An emphasis on potential difference
Authors: Rosenthal A. S. , Henderson C.
Published: March 2006

Introductory physics students often fail to develop a coherent conceptual model of electric circuits. In part, this failure occurs because the students did not develop a good understanding of the concept of electric potential. We describe an instructional approach that emphasizes the electric potential and the electric potential difference. Examples are given to illustrate this approach and how it differs from traditional treatments of these concepts. Assessment data is presented to suggest that this approach is successful in improving student understanding of electric potential and electric circuits.
Force characterization of eddy currents
Authors: Pellicer-Porres J. , Lacomba-Perales R. , Ruiz-Fuertes J. , Martínez-García D. , Andrés M. V.
Published: March 2006

We discuss an experiment for an undergraduate laboratory designed to characterize eddy currents from the forces associated with them. Eddy currents also can be associated with the magnetization and described by a complex magnetic susceptibility. We establish an iterative method for calculating the magnetic susceptibility that is applicable to different geometries without using advanced mathematics. We apply our results to experiments with massive and hollow cylinders for which the susceptibility depends on the geometry. By measuring the force we obtain the cylinders’ conductivity with a contactless technique.
Gaussian beams in the optics course
Authors: Galvez Enrique J.
Published: March 2006

We introduce the physics of high-order Gaussian beams to the treatment of Gaussian beams in the undergraduate optics course. Of particular interest are Laguerre-Gauss beams, which provide the basis for discussing the new and increasingly important concept of the orbital angular momentum of light. We also describe laboratory exercises that complement the class material.
Teaching Faraday’s law of electromagnetic induction in an introductory physics course
Authors: Galili Igal , Kaplan Dov , Lehavi Yaron
Published: March 2006

Teaching Faraday’s law of electromagnetic induction in introductory physics courses is challenging. We discuss some inaccuracies in describing a moving conductor in the context of electromagnetic induction. Among them is the use of the ambiguous term “area change” and the unclear relation between Faraday’s law and Maxwell’s equation for the electric field circulation. We advocate the use of an expression for Faraday’s law that shows explicitly the contribution of the time variation of the magnetic field and the action of the Lorentz force, which are usually taught separately. This expression may help students’ understanding of Faraday’s law and lead to improved problem solving skills.
Using visualizations to teach electrostatics
Authors: Casperson Janet M. , Linn Marcia C.
Published: March 2006

We investigate the effect of visualizations of electrostatics phenomena on students’ ability to integrate microscopic and macroscopic views of electrostatics in the context of a technology-enhanced inquiry project that features particle interactions. We used knowledge integration instructional design patterns to determine activity sequences. A pretest/post-test design was used to assess the students’ overall gains. The results from the implementation of the project in two classes demonstrate that it helped students form a more integrated understanding of electrostatics. An analysis of student responses to prompts embedded with the visualizations reveals that interactions with the visualizations played a significant role in increasing understanding.
PHASE TRANSITION IN A SEXUAL AGE-STRUCTURED MODEL OF LEARNING FOREIGN LANGUAGES
Authors: SCHWÄMMLE V.
Published: March 2006

The understanding of language competition helps us to predict extinction and survival of languages spoken by minorities. A simple agent-based model of a sexual population, based on the Penna model, is built in order to find out under which circumstances one language dominates other ones. This model considers that only young people learn foreign languages. The simulations show a first order phase transition of the ratio between the number of speakers of different languages with the mutation rate as control parameter.
A LATTICE BOLTZMANN STUDY OF THE 2D BOUNDARY LAYER CREATED BY AN OSCILLATING PLATE
Authors: CAPPIETTI L. , CHOPARD B.
Published: March 2006

We study the applicability of the Lattice Boltzmann Method (LBM) to simulate the 2D laminar boundary layer induced by an oscillating flat plate. We also investigate the transition to the disturbed laminar regime that occurs with a rough oscillating plate. The simulations were performed in two cases: first with a fluid otherwise at rest and second in presence of superimposed current. The generation of coherent vortex structures and their evolution are commented. The accuracy of the method was checked by comparisons with the exact analytical solution of the Navier–Stokes equations for the so-called Stokes' Second Problem. The comparisons show that LBM reproduces this time varying flow with first order accuracy. In the case of the wavy-plate, the results show that a mechanism of vortex-jet formations, low speed-streak and shear instability sustain a systems of stationary vortices outside the boundary layer. The vortex-jet takes place at the end of the decelerating phase whereas the boundary layer turns out to be laminar when the plate accelerates. In the presence of the superimposed current, the vortex-jet mechanism is still effective but the vortices outside the boundary layer are only present during part of the oscillating period. During the remaining part, the flow turns out to be laminar although a wave perturbation in the velocity field is present.
ASYMMETRY OF RETURNS IN THE AUSTRALIAN STOCK MARKET
Authors: GUNNER SUSAN M. , BROOKS LOUISE , STORER ROBIN G.
Published: March 2006

We use econophysics techniques to investigate the characteristics of the distribution of returns from the All Ordinaries Index and from optimal portfolios constructed from individual stocks on the Australian Stock Exchange. We find in general that the tails of the distributions are asymmetric and that the negative tail favours a power-law behaviour while the positive tail is more Gaussian.
OPTIMAL VELOCITY MODEL WITH RELATIVE VELOCITY
Authors: SAWADA SHIRO
Published: March 2006

The optimal velocity model which depends not only on the headway but also on the relative velocity is analyzed in detail. We investigate the effect of considering the relative velocity based on the linear and nonlinear analysis of the model. The linear stability analysis shows that the improvement in the stability of the traffic flow is obtained by taking into account the relative velocity. From the nonlinear analysis, the relative velocity dependence of the propagating kink solution for traffic jam is obtained. The relation between the headway and the velocity and the fundamental diagram are examined by numerical simulation. We find that the results by the linear and nonlinear analysis of the model are in good agreement with the numerical results.
CRITICAL SHORT-TIME DYNAMICS IN LATTICE GAUGE THEORY
Authors: OTOBE TSUYOSHI , OKANO KEISUKE
Published: March 2006

We investigated a critical short-time relaxation in a lattice gauge theory. A systematic procedure of estimating critical point based on the "short-time scaling" is formulated. It is applied to the (2+1)-dimensional SU(2) lattice gauge theory at finite temperature to deduce its critical point. Finally, we studied the short-time relaxation behavior at the critical temperature starting either from "cold" and "hot" initial configuration, and calculated the dynamic critical exponents θ and z, as well as the static exponents β/ν.
NONCOMMUTATIVITY FROM EMBEDDING TECHNIQUES
Authors: SAMANTA SAURAV
Published: March 2006

We apply the embedding method of Batalin–Tyutin for revealing noncommutative structures in the generalized Landau problem. Different types of noncommutativity follow from different gauge choices. This establishes a duality among the distinct algebras. An alternative approach is discussed which yields equivalent results as the embedding method. We also discuss the consequences in the Landau problem for a non-constant magnetic field.
COLLECTIVE FLOW DISTRIBUTIONS AND NUCLEAR STOPPING IN HEAVY-ION COLLISIONS AT AGS, SPS AND RHIC
Authors: FENG SHENGQIN , YUAN XIANBAO , SHI YAFEI
Published: March 2006

We study the production of proton, antiproton and net-proton at AGS, SPS and RHIC within the framework of non-uniform flow model (NUFM) in this paper. It is found that the system of RHIC has stronger longitudinally non-uniform feature than that of AGS and SPS, which means that nuclei at RHIC energy region is much more transparent. The NUFM model provides a very good description of all proton rapidity at the whole AGS, SPS and RHIC. It is shown that our analysis relates closely to the study of nuclear stopping and longitudinally non-uniform flow distribution of experiment. This comparison with AGS and SPS help us to understand the feature of particle stopping of thermal freeze-out at RHIC experiment.
EMERGENCE OF TIME FROM DIMENSIONAL REDUCTION IN NONCOMMUTATIVE GEOMETRY
Authors: CHU CHONG-SUN , LECHTENFELD OLAF
Published: March 2006

By considering a new form of dimensional reduction for noncommutative field theory, we show that the signature of spacetime may be changed. In particular, it is demonstrated that a temporal dimension can emerge from a purely Euclidean geometry. We suggest that this mechanism may hint at the origin of time in the fundamental theory of quantum gravity.
DETECTION OF MULTIPLE FACES IN AN IMAGE USING SKIN COLOR INFORMATION AND LINES-OF-SEPARABILITY FACE MODEL
Authors: HIREMATH P. S. , DANTI AJIT
Published: March 2006

In this paper, human faces are detected using the skin color information and the Lines-of-Separability (LS) face model. The various skin color spaces based on widely used color models such as RGB, HSV, YCbCr, YUV and YIQ are compared and an appropriate color model is selected for the purpose of skin color segmentation. The proposed approach of skin color segmentation is based on YCbCr color model and sigma control limits for variations in its color components. The segmentation by the proposed method is found to be more efficient in terms of speed and accuracy. Each of the skin segmented regions is then searched for the facial features using the LS face model to detect the face present in it. The LS face model is a geometric approach in which the spatial relationships among the facial features are determined for the purpose of face detection. Hence, the proposed approach based on the combination of skin color segmentation and LS face model is able to detect single as well as multiple faces present in a given image. The experimental results and comparative analysis demonstrate the effectiveness of this approach.
MATHEMATICAL ANALYSIS OF THE EVOLUTION OF A MODEL OF REGIONAL POPULATION DISTRIBUTION
Authors: EL GHORDAF J. , HBID M. L.
Published: March 2006

This paper deals with the mathematical analysis of a model of urban dynamics, which was proposed by Miyata and Yamaguchi in the context of a region of Japan. The model is a complex system of first-order nonlinear ordinary differential equations. The study undertaken by Miyata and Yamaguchi is essentially computational, while an extensive study of the asymptotic behavior of the solutions is performed in this paper related to a detailed analysis of the qualitative properties of the system.
DYNAMIC STABILITY OF AN AXIALLY ACCELERATING VISCOELASTIC BEAM WITH TWO FIXED SUPPORTS
Authors: YANG X.-D. , CHEN L.-Q.
Published: March 2006

The dynamic stability of an axially accelerating viscoelastic beam with two fixed supports is investigated. The Kelvin model is used for the constitutive law of the beam. A small simple harmonic is allowed to fluctuate about the constant mean speed applied to the beam, and the governing equation is truncated using the Galerkin method based on the eigenfunctions of the stationary beam. The averaged equations are derived for the cases of subharmonic and combination resonance. Finally, numerical examples are presented to demonstrate the effects of the viscosity coefficient, the mean axial speed and the beam bending stiffness on the stability boundaries.
FREE VIBRATION RESPONSE OF SHEAR-FLEXIBLE MODERATELY-THICK ORTHOTROPIC CYLINDRICAL SHELLS
Authors: SAKKA Z. I. , ABDALLA J. A. , KABIR H. R. H.
Published: March 2006

The free vibration response of shear-flexible moderately-thick orthotropic cylindrical shell panels, with fixed edges, is investigated using an analytical approach. The governing partial differential equations are developed based on Sander's kinematics and are solved using generalized Navier's with a boundary continuous double Fourier series expansion. The frequencies and mode shapes from the analytical solution for various parametric ratios, including degree of orthotropy (stiffness ratio), radius-to-segment ratio and segment-to-thickness ratio are compared with the finite element solutions that are based on an eight-node 48 degrees of freedom shell element. The rate of convergence of the analytical solution method with respect to the number of Fourier series terms, for various parametric ratios, is presented. The results of the analytical solution are very comparable to that of the finite element solution. It is clear that the presented analytical solution can be used as a benchmark to calibrate and validate numerical and finite element solutions that usually involve approximation to shell theories.
A TAXONOMY OF CLOSED AND OPEN SOURCE SOFTWARE INDUSTRY BUSINESS MODELS
Authors: HEMPHILL THOMAS A.
Published: March 2006

This paper explores the closed source/open source software model dialectic and presents a conceptual framework of an emerging "both source" software business model useful for formulating firm technology strategy. The author reviews the academic literature and popular business press, extracting definitions and concepts underlying these software models; explains the concept of a business model and makes the case for the knowledge-based view of the firm as the approach to software industry business model development; describes, in detail, the proprietary, open source and "both source" software models; identifies the primary motivations behind the managerial development and adoption of the "both source" business software model (cost containment) and the implementation challenges firm's face (an upsurge in copyright and patent infringement suits concerning adoption of open source code); and concludes with a series of research questions pertaining to the economic viability of open source license business models, the effectiveness of indemnification strategies against copyright and patent infringement, and the managerial motivations behind choosing patent over copyright protection of software inventions.
ALWAYS THE LITTLE BROTHER? DIGITAL-PRODUCT INNOVATION IN THE MEDIA SECTOR
Authors: ELLONEN HANNA-KAISA , KARHU PIIA
Published: March 2006

This article concerns digital-product innovation within the media sector. From previous literature we identify eight factors affecting innovation work. Using material from narratives collected from experts within the media industry, we then present a specific framework that summarizes the factors affecting digital innovations either negatively or positively. We identify three underlying phenomena in the Finnish media sector that explain its specific features: First, it is a small market with a long history, second, digital innovations are in the underdog position and thirdly, the brand positions are strong.
ANALOGY AS A TOOL FOR COMMUNICATING ABOUT INNOVATION
Authors: SIFONIS CYNTHIA , CHERNOFF ADRIAN , KOLPASKY KEVIN
Published: March 2006

Many techniques have been developed to enhance innovative thinking within a company. However, many innovations never make it through the development process due to the difficulty inherent in communicating new ideas to others. This article discusses the obstacles to innovation that occur during the development process and how these obstacles can be overcome through the use of analogy. Described is an empirically derived seven-step process for constructing suitable analogies for communicating about innovations. The use of the seven-step processes to develop an analogy to communicate about an automotive "step-rim" innovation developed by General Motors and the lessons learned during the development of the analogy are also discussed.
MODULI OF QUANTA
Authors: ISIDRO JOSÉ M.
Published: March 2006

The classical phase of the matrix model of 11-dimensional M-theory is complex, infinite-dimensional Hilbert space. As a complex manifold, the latter admits a continuum of nonequivalent, complex-differentiable structures that can be placed in 1-to-1 correspondence with families of coherent states in the Hilbert space of quantum states. The moduli space of nonbiholomorphic complex structures on classical phase space turns out to be an infinite-dimensional symmetric space. We argue that each choice of a complex differentiable structure gives rise to a physically different notion of an elementary quantum.
THE YANG–MILLS EQUATIONS AND THE INTERSECTION OF QUARTICS IN PROJECTIVE 4-SPACE ℂℙ4
Authors: LESFARI A. , ELACHAB A.
Published: March 2006

In this paper, we discuss an interesting interaction between complex algebraic geometry and dynamics: the integrability of the Yang–Mills system for a field with gauge group SU(2) and the intersection of quartics in projective 4-space ℂℙ4. Using Enriques classification of algebraic surfaces and dynamics, we show that these two quartics intesect in the affine part of an abelian surface and it follows that the system of differential equations is algebraically completely integrable.
JARLSKOG'S PARAMETRIZATION OF UNITARY MATRICES AND QUDIT THEORY
Authors: FUJII KAZUYUKI , FUNAHASHI KUNIO , KOBAYASHI TAKAYUKI
Published: March 2006

In the paper (math–ph/0504049) Jarlskog gave an interesting simple parametrization to unitary matrices, which was essentially the canonical coordinate of the second kind in the Lie group theory (math–ph/0505047). In this paper we apply the method to a quantum computation based on multilevel system (qudit theory). Namely, by considering that the parametrization gives a complete set of modules in qudit theory, we construct the generalized Pauli matrices, which play a central role in the theory and also make a comment on the exchange gate of two–qudit systems. Moreover, we give an explicit construction to the generalized Walsh–Hadamard matrix in the case of n = 3, 4, and 5. For the case of n = 5, its calculation is relatively complicated. In general, a calculation to construct it tends to become more and more complicated as n becomes large. To perform a quantum computation the generalized Walsh–Hadamard matrix must be constructed in a quick and clean manner. From our construction it may be possible to say that a qudit theory with n ≥ 5 is not realistic. This paper is an introduction toward Quantum Engineering.
The Role of Media Violence in Violent Behavior
Authors: Huesmann L. Rowell , Taylor Laramie D.
Published: March 2006

▪ Abstract  Media violence poses a threat to public health inasmuch as it leads to an increase in real-world violence and aggression. Research shows that fictional television and film violence contribute to both a short-term and a long-term increase in aggression and violence in young viewers. Television news violence also contributes to increased violence, principally in the form of imitative suicides and acts of aggression. Video games are clearly capable of producing an increase in aggression and violence in the short term, although no long-term longitudinal studies capable of demonstrating long-term effects have been conducted. The relationship between media violence and real-world violence and aggression is moderated by the nature of the media content and characteristics of and social influences on the individual exposed to that content. Still, the average overall size of the effect is large enough to place it in the category of known threats to public health.
HYPERTENSION: Trends in Prevalence, Incidence, and Control
Authors: Hajjar Ihab , Kotchen Jane Morley , Kotchen Theodore A.
Published: March 2006

▪ Abstract  Hypertension is the leading cause of cardiovascular disease worldwide. Prior to 1990, population data suggest that hypertension prevalence was decreasing; however, recent data suggest that it is again on the rise. In 1999–2002, 28.6% of the U.S. population had hypertension. Hypertension prevalence has also been increasing in other countries, and an estimated 972 million people in the world are suffering from this problem. Incidence rates of hypertension range between 3% and 18%, depending on the age, gender, ethnicity, and body size of the population studied. Despite advances in hypertension treatment, control rates continue to be suboptimal. Only about one third of all hypertensives are controlled in the United States. Programs that improve hypertension control rates and prevent hypertension are urgently needed.
Glycogenin, proglycogen, and glycogen biogenesis: what’s the story?
Authors: Katz Abram
Published: March 2006

Glycogenin is the self-glycosylating protein primer that initiates glycogen granule formation. To examine the role of this protein during glycogen resynthesis, eight male subjects exercised to exhaustion on a cycle ergometer at 75% V̇o2 maxfollowed by five 30-s sprints at maximal capacity to further deplete glycogen stores. During recovery, carbohydrate (75 g/h) was supplied to promote rapid glycogen repletion, and muscle biopsies were obtained from the vastus lateralis at 0, 30, 120, and 300 min postexercise. At time 0, no free (deglycosylated) glycogenin was detected in muscle, indicating that all glycogenin was complexed to carbohydrate. Glycogenin activity, a measure of the glycosylating ability of the protein, increased at 30 min and remained elevated for the remainder of the study. Quantitative RT-PCR showed elevated glycogenin mRNA at 120 min followed by increases in protein levels at 300 min. Glycogenin specific activity (glycogenin activity/relative protein content) was also elevated at 120 min. Proglycogen increased at all time points, with the highest rate of resynthesis occurring between 0 and 30 min. In comparison, macroglycogen levels did not significantly increase until 300 min postexercise. Together, these results show that, during recovery from prolonged exhaustive exercise, glycogenin mRNA and protein content and activity increase in muscle. This may facilitate rapid glycogen resynthesis by providing the glycogenin backbone of proglycogen, the major component of glycogen synthesized in early recovery.
Hormonal regulation of hepatic multidrug resistance-associated protein 2 (Abcc2) primarily involves the pattern of growth hormone secretion
Authors: Simon Francis R. , Iwahashi Mieko , Hu Ling-Jia , Qadri Ishtiaq , Arias Irwin M. , Ortiz Daniel , Dahl Rolf , Sutherland Eileen
Published: March 2006

Biliary excretion is the rate-limiting step in transfer of bilirubin, other organic anions, and xenobiotics across the liver. Multidrug resistance-associated protein 2 (Mrp2, Abcc2) is the major transporter for conjugated endo- and xenobiotic-conjugated compounds into bile. Hormones regulate bilirubin and xenobiotic secretion into bile, which have dimorphic differences. Therefore, we examined the possible role of sex steroids and growth hormone in the regulation of Mrp2. In ∼8-wk-old rats, mRNA, transcriptional activity, and hepatic content of Mrp2 were selectively increased fourfold ( P < 0.001) in females compared with males. In males, estrogens increased and testosterone decreased Mrp2 mRNA and protein, whereas no significant effect was measured in females, suggesting either a direct effect on the liver or an alteration in growth hormone secretory pattern. After hypophysectomy, Mrp2 mRNA was markedly reduced and the effects of estrogens and testosterone on Mrp2 were prevented, supporting the role of pituitary hormones in controlling Mrp2 expression. Mrp2 increased following growth hormone infusion in males. Mrp2 mRNA was decreased in growth hormone-deficient “Little” mice. Growth hormone infusions in hypophysectomized rats partially restored Mrp2 levels, whereas thyroxine addition returned Mrp2 mRNA and protein to basal levels. Morphology as well as biochemical measurements demonstrated that Mrp2 was localized to the bile canaliculus in equal density in both genders, whereas hormone replacements increased Mrp2 in hypophysectomized animals. In cultured hepatocytes, thyroxine did not have an effect, but growth hormone alone and combined with thyroxine increased Mrp2 mRNA levels. In conclusion, Mrp2 levels are regulated by the combination of thyroxine and different growth hormone secretory patterns.
Mechanisms of Liver Injury. I. TNF-α-induced liver injury: role of IKK, JNK, and ROS pathways
Authors: Schwabe Robert F. , Brenner David A.
Published: March 2006

TNF-α activates several intracellular pathways to regulate inflammation, cell death, and proliferation. In the liver, TNF-α is not only a mediator of hepatotoxicity but also contributes to the restoration of functional liver mass by driving hepatocyte proliferation and liver regeneration. This review summarizes recent advances in TNF-α signaling mechanisms that demonstrate how the IKK, ROS, and JNK pathways interact with each other to regulate hepatocyte apoptosis and proliferation. Activation of these pathways is causatively linked to liver injury induced by concanavalin A, TNF-α, and ischemia-reperfusion and to liver regeneration and hepatocarcinogenesis. In light of recent findings, pharmacological inhibitors of JNK and IKK and antioxidants may be promising new tools for the treatment of hepatitis, ischemia-reperfusion injury, and hepatocellular carcinoma.