bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of saturated and aromatic hydrocarbons oil-oil maturity correlation parameters (SE Pannonian Basin, Serbia)
Authors: Stojanovic Ksenija , Jovancicevic Branimir , Vitorovic Dragomir , Golovko Yulia , Pevneva Galina , Golovko Anatoly
Published: January 2008

Twenty three crude oils from the Serbian part of the Pannonian Basin (14 from the Vojvodina Province and 9 from the Drmno Depression) were investigated, aimed at an evaluation of oil-oil maturity correlation parameters based on the distribution and abundance of saturated biomarkers and alkylarene constituents. Factor and cluster analyses were used for this purpose. Factor analyses using varimax rotation were first run separately, i.e., of maturity parameters based on the abundance of (a) n-alkanes and isoprenoids, (b) steranes and triterpanes, (c) alkylnaphthalenes, and (d) alkylphenanthrenes. These analyses yielded 9 important "maturity factors". Eight of them, showing higher than 30 % of variance, were further involved in another factor analysis, as well as in cluster analysis using the Ward method. In this way, all maturity parameters based on saturated biomarkers and alkylarenes were evaluated and ranged, considering the fact that the observed factors represented their linear combinations. The results showed that in the correlation of crude oils from the Serbian part of the Pannonian Basin, the most important were maturity parameters based on isomerization reactions involving one methyl group in thermodynamically less stable ?-methylnaphthalenes, ethylnaphthalenes, dimethylnaphthalenes and methylphenanthrenes, and their change into more stable isomers with the methyl group in the ?-position in the aromatic ring. Processes constituting high loadings factor 2 and factor 3 parameters were also defined. Hierarchy between the "factors" and parameters were controlled, and approved, by cluster analysis using the Ward method. Finally, the investigated crude oils were correlated by factor and cluster analyses, using all the important "maturity factors". Differences in maturity were observed between the Vojvodina and Drmno Depression crude oils, as well as between oils originating from South Banat, North Banat and the Velebit oil field (Vojvodina locality).
Preparation and studies on immobilized α-glucosidase from baker’s yeast Saccharomyces cerevisiae
Authors: Ahmed Khaled , Milosavic Nenad , Popovic Milica , Prodanovic Radivoje , Knezevic Zorica , Jankov Ratko
Published: January 2008

?-Glucosidase from S. cerevisiae was covalently immobilized onto Sepabeads EC-EA by the glutaraldehyde method. An analysis of the variables controlling the immobilization process is first presented and it is shown that the highest coupling of ?-glucosidase occurred within 24 h. Also, a loading of 30 mg/g support proved to be effective, resulting in a rather high activity of around 45 U g-1 with a satisfactory degree of enzyme fixed. Both free and immobilized enzymes were then characterized by determining the activity profile as a function of pH, temperature and thermal stability. The obtained immobilized preparation showed the same optimum pH, but a higher optimum temperature compared with the soluble one. In addition, the immobilized enzyme treated at 45 ?C for 1 h still retained an activity of around 20 %, whereas the free enzyme completely lost its original activity under this condition. In conclusion, the developed immobilization procedure is quite simple, easily reproducible and provides a promising solution for the application of immobilized ?-glucosidase.
Relating Estrada index with spectral radius
Authors: Gutman Ivan , Radenkovic Slavko , Furtula Boris , Mansour Toufik , Schork Matthias
Published: January 2008

The Estrada index EE is a recently proposed molecular structure-descriptor, used in the modeling of certain features of the 3D structure of organic molecules, in particular of the degree of folding of proteins and other long-chain biopolymers. The Estrada index is computed from the spectrum of the molecular graph. Therefore, finding its relation with the spectral radius r (= the greatest graph eigenvalue) is of interest, especially because the structure-dependency of r is relatively well understood. In this work, the basic characteristics of the relation between EE and r, which turned out to be much more complicated than initially anticipated, was determined.
Thermally induced conversion of Mg2+ cation exchanged LTA, FAU, GIS and SOD zeolites: Syntheses and characterization of γ-cordierite, a new Mg2Al4Si5O18 polymorph
Authors: Dimitrijevic Radovan , Dondur Vera
Published: January 2008

The thermal behaviours of fully Mg2+ cation exchanged LTA, FAU (X and Y species), GIS and SOD zeolites were investigated in the temperature range from ambient to 1400 ?C. The initial zeolite frameworks collapsed into amorphous intermediate substances after air heating between 800-850 ?C. Prolonged annealing of these products above 850 ?C induced recrystallization into sapphirine-like phases (Mg-LTA and Mg-FAUx zeolites) and ?-cordierite (Mg-FAUy and Mg-GIS zeolites) phases. These phases were unstable during further temperature/time treatment and between 1000-1100 ?C they polymorphously transformed into ?-cordierite, a new Mg2Al4Si5O18 polymorph. ?-Cordierite was formed as a transformation product from the investigated zeolite precursors, except for the Mg-SOD zeolite. Structurally the ?-cordierite phase is a modulated, Mg-stuffed derivative of cristobalite with the approximate composition Mg2Al4Si5O18, which precedes the appearance of ?-cordierite. The orthorhombic unit cell dimensions calculated from X-ray powder diffraction pattern are: a = 16.387(7) ?, b = 8.835(4) ?, c = 7.853(3) ?. ?-Cordierite has a narrow range of temperature stability (1100-1200 ?C) and during prolonged temperature/time treatment, it is polymorphously transformed to the ?-cordierite phase.
A study of the electrochemical activity of some macrolide antibiotics on a gold electrode in a neutral electrolyte
Authors: Avramov-Ivic Milka , Petrovic Slobodan , Mijin D.Z.
Published: January 2008

The aim of the present study is to present the different reactivity of azithromycin and clarithromycin (pure and commercial) at a gold electrode in neutral electrolyte using cyclic linear sweep voltammetry under the same experimental conditions. A gold electrode was successfully used for the electrochemical qualitative and quantitative determination of azithromycin dihydrate and azithromycin from capsules (Hemomycin?) and for the separation of azithromycin from one of the excipients, lactose monohydrate. The good catalytically activity of the gold electrode was employed only for the qualitative electrochemical determination of pure clarithromycin by appearance of one cathodic and four anodic reactions, which enabled structural changes in this molecule during electrochemical reactions to be studied. Commercial clarithromycin, Clathrocyn? was qualitative determined by one reproducible anodic reaction. The activity of one of the excipients, Avicel, observed as a cathodic peak at different potential from the cathodic peak obtained with pure clarithromicin was used for the determination of its presence in Clathrocyn? tablets. FTIR Analysis showed the apparent changes in structure of pure clarithromycin, as well as in the molecule of clarithromycin in Clathrocyn? tablets. HPLC Analysis showed a significant decrease in the concentration of azithromycin, Hemomycin? clarithromycin and Clathrocyn? after the electrochemical reactions.
Photocatalytic removal of the herbicide clopyralid from water
Authors: Abramovic Biljana , Anderluh Vesna , Sojic Daniela , Gaál Ferenc
Published: January 2008

The stability of the herbicide clopyralid (3,6-dichloro-2-pyridinecarboxylic acid) was studied under different experimental conditions of pH, illumination and initial substrate concentration. It was found that in the pH interval from 1.0 to 9.0 in the presence/absence of daylight, clopyralid solutions were stable for at least a period of two months. The kinetics of the photocatalytic degradation of clopyralid in aqueous suspensions of TiO2 (Degussa P25) under UV and visible light, as well as of direct photolysis using the same radiation sources, were also investigated. It was found that the rate of photocatalytic degradation in the presence of UV light was more than five times higher compared to direct photolysis, whereas in the presence of visible light, the corresponding rates of photocatalytic/photolytic degradation were much lower (more than 15 times). The reaction in the investigation concentration range is zero-order with respect to the degradation of the clopyralid pyridine moiety, with a reaction rate of 3.4?10-6 mol dm-3 min-1 and an adsorption coefficient of the substrate of 2.5?104 dm3 mol-1.
Properties of aliphatic hyperbranched polyesters in dilute solutions
Authors: Vukovic Jasna , Lechner Manfred , Jovanovic Slobodan
Published: January 2008

The results of an investigation of the influence of the synthesis procedure, number of pseudo generations and degree of branching of hydroxy-functional aliphatic hyperbranched polyesters (AHBP) on the values of limiting viscosity number, [?], hydrodynamic radius, R?, molar mass and polydispersity index, Q, are presented in this paper. Two series of AHBP, synthesized from 2,2-bis(hydroxymethyl) propionic acid and di-trimethylolpropane using a pseudo-one-step and a one-step procedure were investigated. The obtained results show that the values of [?] and R? for all examined samples are the highest in a 0.7 mass % solution of LiCl in N,N-dimethylacetamide (LiCl/DMAc), which indicates that this solvent is the best from the investigated ones. The values of [?] in N-methyl-2-pyrrolidinone (NMP) increased up to the sixth pseudo generation, after which a slight decrease occurred as the consequence of the presence of side-reaction products, formed during the synthesis. The appearance of these side-reaction products was also confirmed from the characteristic GPC chromatograms. For the samples of AHBP synthesized using the pseudo- one-step procedure, a good linear dependence between log [?] and log Mw was obtained up to the fifth pseudo generation, when LiCl/DMAc, NMP and DMAc were used as solvents. The values of the "shrinking" factor, g?, were calculated for all investigated AHBPs.
HCO+ in dark molecular clouds
Authors: Nikolic S.
Published: January 2008

Formyl ion is one of the most important molecules, and primary molecular ion to be found in molecular clouds. This paper reviews chemical pathways of formation and destruction of the molecule, as well as its use as a tool in the study of dark molecular clouds.
Simulations of the broad line region of NGC 5548 with CLOUDY code: Temperature determination
Authors: Ilic D.
Published: January 2008

In this paper an analysis of the physical properties of the Broad Line Region (BLR) of the active galaxy NGC 5548 is presented. Using the photoionization code CLOUDY and the measurements of Peterson et al. (2002), the physical conditions of the BLR are simulated and the BLR temperature is obtained. This temperature was compared to the temperature estimated with the Boltzmann-Plot (BP) method (Popovic et al. 2007). It was shown that the measured variability in the BLR temperature could be due to the change in the hydrogen density.
On the timescale forcing in astrobiology
Authors: Vukotic B. , Cirkovic M.M.
Published: January 2008

We investigate the effects of correlated global regulation mechanisms, especially Galactic gamma-ray bursts (GRBs), on the temporal distribution of hypothetical inhabited planets, using simple Monte Carlo numerical experiments. Starting with recently obtained models of planetary ages in the Galactic Habitable Zone (GHZ), we obtain that the times required for biological evolution on habitable planets of the Milky Way are highly correlated. These results run contrary to the famous anti-SETI anthropic argument of Carter, and give tentative support to the ongoing and future SETI observation projects.
Characterization of bismuth titanate ceramics derived by mechanochemical synthesis
Authors: Lazarevic Z.Z. , Stojanovic B.D. , Paiva-Santos C.O. , Romcevic N.Z. , Varela J.A.
Published: January 2008

Bismuth titanate, Bi4Ti3O12 (BIT) nanosized powders have been successfully synthesized via high energy mechanochemical activation. The phase formation of BIT, crystal structure, microstructure, crystallite size and specific surface area were followed by XRD, scanning electron microscopy (SEM) and the BET specific surface area measurements. The BIT milled 2 h shows the orthorhombic crystalline structure with small amount of amorphous phase. The microstructure of Bi4Ti3O12 ceramics sintered at 1000?C for 12h exhibit plate-like grain structure.
Conducting materials based on nanodispersed titanium monoxide
Authors: Gusev A.A. , Avvakumov E.G.
Published: January 2008

The possibility of obtaining the TiO compound during mechanical activation of rutile and titanium in a planetary mill was studied depending on ball size and the activation time. The initial substances, TiO2 (rutile) and Ti (metal), were shown to change into TiO almost completely during grinding as early as after ten minutes. In this case the cubic modification of TiO formed, with the lattice parameter a=4.185(7) ? and particles of 1-3 ?m, which consisted of units about 10 nm in size. The other subject of our research was the dependence of the conductivity of the products on the conditions under which they were moulded and sintered under argon. The conductivity of the samples was in the range 300 to 600 S cm-1. Their chemical resistance equaled that of Ti4O7 samples.
Gender equality and equal opportunity mechanisms in Italy
Authors: Mrsevic Zorica
Published: January 2008

As a country of Southern European mentality Italy may be taken as the nearest-to-the-Balkans model of the gender equality mechanisms and necessity of their existence. Italy also might be taken as a model of domain and methods of functioning of the gender equality mechanisms as well as their connections with the EU development funds. Besides the Italian Ministry for Rights and Equal opportunities and the National Committee, the attention was paid to the whole range of local mechanisms and legal regulations dealing with advancement of women?s employment and counteracting discrimination on the labor market. In the text are analyzed through the five chapters the Italian mechanisms/institutions for gender equality as located within the European institutional environment but also within the context of Italian recent history of struggle against gender based discrimination. It was stressed that the essence of the accumulated European institutional wisdom is in diversity of the gender equality bodies rather then in their uniformity. Although the Italian mechanisms for gender equality are part of the European institutional environment their aim is to meet the internal needs for advancement of gender equality. Besides, the mechanisms also meet the demands of the international standards comprised in the documents issued by the UN and the EU. In European countries these mechanisms are frequently established and function in the domains of the labor and employment regulations, but also are located within the human rights portfolios while somewhere are connected with the minority rights and equal opportunity implementation.
Measurements of higher-order turbulent statistics in a turbulent boundary layer subjected to a short roughness strip
Authors: Oyewola Olanrewaju
Published: January 2008

Hot-wire measurements have been undertaken in a turbulent boundary layer which is subjected to an impulse in form of a short roughness strip with the aim of determining its effect on turbulence structure. The quantifications were made through the measurements of higher-order turbulent statistics. The changes observed in the distributions of correlation coefficient, third-order moments, skew ness and flatness factor relative to the smooth wall suggests that the turbulence structure is modified downstream of the short roughness strip. Relative to the undisturbed smooth wall, the third-order moments were increased in the region between the two internal layers. This increased extends to significant portion of the outer region of the boundary layer. While a gain in turbulent kinetic energy by diffusion occurs throughout the boundary layer for a flow over the short roughness strip, those of the smooth wall occur near the wall.
The transient response for different types of erodable surface thermocouples using finite element analysis
Authors: Mohammed Hussein , Salleh Hanim , Yusoff Mohd
Published: January 2008

The transient response of erodable surface thermocouples has been numerically assessed by using a two dimensional finite element analysis. Four types of base metal erodable surface thermocouples have been examined in this study, included type-K (alumel-chromel), type-E (chromel-constantan), type-T (copper-constantan), and type-J (iron-constantan) with 50 mm thick- ness for each. The practical importance of these types of thermocouples is to be used in internal combustion engine studies and aerodynamics experiments. The step heat flux was applied at the surface of the thermocouple model. The heat flux from the measurements of the surface temperature can be commonly identified by assuming that the heat transfer within these devices is one-dimensional. The surface temperature histories at different positions along the thermocouple are presented. The normalized surface temperature histories at the center of the thermocouple for different types at different response time are also depicted. The thermocouple response to different heat flux variations were considered by using a square heat flux with 2 ms width, a sinusoidal surface heat flux variation width 10 ms period and repeated heat flux variation with 2 ms width. The present results demonstrate that the two dimensional transient heat conduction effects have a significant influence on the surface temperature history measurements made with these devices. It was observed that the surface temperature history and the transient response for thermocouple type-E are higher than that for other types due to the thermal properties of this thermocouple. It was concluded that the thermal properties of the surrounding material do have an impact, but the properties of the thermocouple and the insulation materials also make an important contribution to the net response.
Thermodynamic analysis of heat recovery steam generator in combined cycle power plant
Authors: Ravi Kumar , Rama Krishna , Sita Rama
Published: January 2008

Combined cycle power plants play an important role in the present energy sector. The main challenge in designing a combined cycle power plant is proper utilization of gas turbine exhaust heat in the steam cycle in order to achieve optimum steam turbine output. Most of the combined cycle developers focused on the gas turbine output and neglected the role of the heat recovery steam generator which strongly affects the overall performance of the combined cycle power plant. The present paper is aimed at optimal utilization of the flue gas recovery heat with different heat recovery steam generator configurations of single pressure and dual pressure. The combined cycle efficiency with different heat recovery steam generator configurations have been analyzed parametrically by using first law and second law of thermodynamics. It is observed that in the dual cycle high pressure steam turbine pressure must be high and low pressure steam turbine pressure must be low for better heat recovery from heat recovery steam generator.
Development a micro hydro power scheme at the weir on Black Timok
Authors: Jevtic Miroljub
Published: January 2008

The micro hydro power scheme (MHPS), as a practical realization of research project supported from Ministry of Science of the Republic of Serbia, is presented in the paper. MHPS was constructed on the Black Timok (East Serbia) at the deserted weir. MHPS can be used as a model for other similar sites with extremely low head. On this way, the contribution to approaching to Directive EU for renewable energy sources was done. The results of project are summed in the paper. The method of turbine type selection by use of nomogram is presented. The results of dimensions scaling of existing smaller turbine are given. On the base of these results, the turbine of 5 times higher dimensions was designed and made. The results of estimation and measuring the parameters of this turbine are compared. Designed and constructed powerhouse of MHPS, which is jointed to existing weir, is described. The results of energy efficiency and ecological effects analysis of MHPS are given in the paper.
Readiness for changes: New competences for knowledge society
Authors: Djurisic-Bojanovic Mirosava
Published: January 2008

In the conditions of high instability, uncertainty and changing of environment of contemporary organizations, management of changes and knowledge become priority social strategies, and readiness for changes, flexible usage of knowledge and creativity become the most important competences of people in contemporary organizations. Knowledge, creativity, taking initiative and readiness for changes are the condition of development, survival and success of organizations, but of individuals as well. Our basic question is aimed at the possibilities of the contribution of basic education to the preparation of the young for working in turbulent environment, where work and professional competences involve readiness for changes and innovativeness. In terms of educational policy it implies the need for the creation of upbringing- educational model which will be capable of providing optimal answers to the changes in environment. The key notion of pluralist educational concept, based on democratic values, is the acceptance of the plurality of ideas. Our researches suggest a significant positive correlation between the variables tolerance of independence and the acceptance of the plurality of ideas. Based on that fact, using the theoretical analytical method, this paper argues the compatibility of pluralist concept in education with the demands of contemporary organizations from the perspective of preparing the young for the inclusion in work in the uncertain, changeable organizational environment of knowledge society.
Educational research and education of teachers
Authors: Vujisic-Zivkovic Natasa
Published: January 2008

The development of research competence is one of the basic demands of the contemporary programs of professional education of teachers. This paper discusses the question of the relation between educational research and education of teachers. Examination of different models of the inclusion of educational research into the programs of education of teachers demands first to shed light on, sometimes concealed, epistemological-methodological assumptions on which they are based. As a starting point for the consideration of problem of the relation between educational research and education of teachers, the circle of questions stemming from dichotomy theory-practice was analyzed. In that context, the problem of the relation of practicians towards educational research was emphasized. The relation between educational research and education of teachers in the model of "reflective practician" and model of education of "teacher researcher" was analyzed. The analysis indicates that the development of methodology of educational research is one of the key aspects of the advancement of the program of teacher education.
Achievement motive of future physical education teachers
Authors: Lazarevic Dusanka , Trebjesanin Biljana
Published: January 2008

This paper presents the results of the research of the characteristics of achievement motive of future physical education teachers. Starting from understanding of the importance of achievement motive for the successful accomplishment of professional goals and roles of teachers, the aim of our research is to examine the level of achievement motive, the characteristics of its structure and differences according to gender. The instrument MOP2002 (Francesko et al., 2002a) was applied, which presupposes the complex structure of this motive. The sample consisted of 373 students (263 male and 110 female) of the Faculty of Sport and Physical Education in Belgrade. The results show that their achievement motive is characterized by the tendency towards high level of presence, and its structure is in the largest degree determined by the components accomplishing goals as a source of pleasure and perseverance in accomplishing goals, which is followed by orientation towards planning. The component competing with others is demonstrated in a moderate degree and it is least expressed. It was shown that female students have a larger degree of achievement motive when compared to male students, and accomplishing goals as a source of pleasure and perseverance in accomplishing goals mostly contribute to the difference in structure of achievement motive. It can be expected that the achievement motive, with the structure and degree of presence determined in our respondents, will contribute that they, as future teachers, become a good motivational model and the creators of a desirable motivational climate.
Self-regulation in learning: Application of strategies and roles of orientation towards goals
Authors: Mirkov Snezana
Published: January 2008

This paper presents different views on self-regulation in the process of learning. What is shown is the model in which self-regulation is treated as the interaction of processes connected to personality, behavioral and contextual processes. The regulation processes are organized in several phases, and within each phase self-regulatory activities are structured in different fields. Special attention is paid to the application of strategies - cognitive, meta-cognitive, motivational and strategies of resource management. As a critical component of self-regulation, the monitoring and the steps it consists of were discussed in more detail. The emphasis is on the role of feedback in monitoring, as well as on the wider significance it has for self-regulation in the process of learning. Since orientation towards the goal is considered an essential aspect of self-regulation, what was performed was the analysis of the results and implications of different researches of the relation of pupils? orientations towards the goals with regulation of the process of learning. The possibilities for encouraging self-regulation in the tuition process were considered. By enabling pupils to make decisions, set their own goals, perform the choice and plan and organize their activities, the development of self-regulation and autonomy is encouraged. The guidelines for planning the training aimed towards the development of strategy behavior in pupils are stated. What is presented are the different methods which are applied within the model and interventions in tuition directed towards encouragement of self-regulation.
Sidel’s criticism of Kerschensteiner’s understanding of work-school
Authors: Kocic Ljubomir
Published: January 2008

This paper discusses Sidel?s criticism of certain Kerschensteiner?s views about work-school and work-education. Sidel disputed that Kerschensteiner was the creator of the idea about work-school, emphasizing that, significantly before Kerschensteiner, he put forth this idea in his papers, in which he proved the pedagogical value of work and the need for work-school. Sidel objects to Kerschensteiner that he did not convincingly elaborate the need for introducing work-school, that, when explaining the need for handcraft, he underestimated the significance of books for education and culture in general, that he did not specify the term "giftedness", that is, that he did not indicate that besides spiritual, there are other kinds of giftedness and that he did not understand correctly the relation between work and obviousness. Sidel also thinks that Kerschensteiner did not understand the relation between the society, state and education, i.e. that he did not demonstrate that school reform is conditioned by social reasons, that work-school is a social an political need, that work education is the need and interest of modern society and state. Also, he objects to Kerschensteiner that he did not understand nor emphasize the significance and value of handcraft for artistic education, that he did not speak about the role of work in the development of inventive spirit of the young, that he did not sufficiently emphasize that significance of handcraft for the development of will, moral and character, that he did not speak in which way work-school can be realized, i.e. he did not see the mutual relationship between social development and school and did not demand any social changes for the purpose of accomplishing that goal. Sidel concludes that Kerschensteiner?s work-school, introduced in the conditions of monarchist organization of schools in Germany, cannot be a role model which should be followed.
Use of the Berg Balance Scale for Predicting Multiple Falls in Community-Dwelling Elderly People: A Prospective Study
Authors: Muir Susan W , Berg Katherine , Chesworth Bert , Speechley Mark
Published: January 2008

Background and Purpose

Falls are a significant public health concern for older adults; early identification of people at high risk for falling facilitates the provision of rehabilitation treatment to reduce future fall risk. The objective of this prospective cohort study was to examine the predictive validity of the Berg Balance Scale (BBS) for 3 types of outcomes—any fall (≥1 fall), multiple falls (≥2 falls), and injurious falls—by use of sensitivity, specificity, receiver operating characteristic (ROC) curves, area under the curve, and likelihood ratios.

Subjects and Methods

A sample of 210 community-dwelling older adults received a comprehensive geriatric assessment at baseline, which included the BBS to measure balance. Data on prospective falls were collected monthly for a year. The predictive validity of the BBS for the identification of future fall risk was evaluated.

Results

The BBS had good discriminative ability to predict multiple falls when ROC analysis was used. However, the use of the BBS as a dichotomous scale, with a threshold of ≤45, was inadequate for the identification of the majority of people at risk for falling in the future, with sensitivities of 25% and 45% for any fall and for multiple falls, respectively. The use of likelihood ratios, maintaining the BBS as a multilevel scale, demonstrated a gradient of risk across scores, with fall risk increasing as scores decreased.

Discussion and Conclusion

The use of the BBS as a dichotomous scale to identify people at high risk for falling should be discouraged because it fails to identify the majority of such people. The predictive validity of this scale for multiple falls is superior to that for other types of falls, and the use of likelihood ratios preserves the gradient of risk across the whole range of scores.
Divergence Property of Formal Solutions for Singular First Order Linear Partial Differential Equations
Authors: Hibino Masaki
Published: January 2008

This paper is concerned with the study of the convergence and the divergence of formal power series solutions of the following first order singular linear partial differential equation with holomorphic coefficients at the origin:

P(x,D)u(x) = \sum^d_{\iota=1}a_\iota(x)D_\iota u(x)+b(x)u(x) = f(x),

with

f(x)

holomorphic at the origin. Here the equation is said to be singular if

a_\iota(0)=0

(

\iota = 1, ...,d

). In this case, it is known that under the so-called Poincare condition, if

\{a_\iota(x)\}^d_{\iota=1 }

generates a simple ideal, every formal solution is convergent. However if we remove these conditions, we shall see that the formal solution, if it exists, may be divergent. More precisely, we will characterize the rate of divergence of formal solutions via Gevrey order of formal solutions determined by a Newton Polyhedron, a generalization of Newton Polygon which is familiar in the study of ordinary differential equations with an irregular singular point.
A Generalization of the Radon–Nikodym Property in Dual Banach Spaces, Fragmentedness, and Differentiability of Convex Functions
Authors: Matsuda Minoru
Published: January 2008

For non-empty bounded subsets
A
of Banach spaces, we introduce the notion of the
A
-Radon–Nikodym property in dual Banach spaces, a slight generalization of the Radon–Nikodym property in such spaces. Making the effective use of this notion and a weak*-measurable function constructed here, we give a direct study of some related properties (especially,
A
-fragmentedness) of weak*-compact subsets of dual Banach spaces.
Hilbert $C^*$-Module Representation on Haagerup Tensor Products and Group Systems
Authors: Heo Jaeseong
Published: January 2008

Using the Hilbert

C^*

-module representation associated with completely multi-positive linear maps [Heo], we give another representation on Haagerup tensor product without the bridging maps. We also construct covariant representations of covariant group systems on Hilbert

C^*

-modules.
Sierpiński Gasket as a Martin Boundary II ($\!\textit{\textsf{The Intrinsic Metric}}$)
Authors: Denker Manfred , Sato Hiroshi
Published: January 2008

It is shown in [DS] that the Sierpiński gasket

\mathscr S \in \boldsymbol R^N

can be represented as the Martin boundary of a certain Markov chain and hence carries a canonical metric

\rho_M

induced by the embedding into an associated Martin space

M

. It is a natural question to compare this metric

\rho_M

with the Euclidean metric. We show first that the harmonic measure coincides with the normalized

H=(\log(N+1)/\log2)

-dimensional Hausdorff measure with respect to the Euclidean metric. Secondly, we define an intrinsic metric

\rho

which is Lipschitz equivalent to

\rho_M

and then show that

\rho

is not Lipschitz equivalent to the Euclidean metric, but the Hausdorff dimension remains unchanged and the Hausdorff measure in

\rho

is infinite. Finally, using the metric

\rho

, we prove that the harmonic extension of a continuous boundary function converges to the boundary value at every boundary point.
Correspondance d'Andreotti–Norguet et $\mathscr D$-Modules
Authors: Frot Jean-Louis
Published: January 2008

We calculate the integral transform of a

\mathscr D

-module of rank

>1

, locally free outside the zero section of the cotangent space to the complex projective space

ℙ_n

. This allows us to complete some results of Andreotti–Norguet and Barlet: in particular we prove that the image of the integral transform obtained by integrating holomorphic forms along the linear cycles of

ℙ_n\backslash ℙ_{n-p-1}

(where

0 < p < n - 1

), is the space of holomorphic functions on the variety of cycles

\mathcal C_p(ℙ_n\backslash ℙ_{n-p-1})

, which are annihilated by a family of differential operators of order four, that we determine explicitly.

Nous calculons l'image par transformation intégrale d'un

\mathscr D

-module de rang

>1

, localement libre en dehors de la section nulle du cotangent à l'espace projectif complexe

ℙ_n

. Ceci nous permet de compléter certains résultats d'Andreotti-Norguet et Barlet: nous montrons en particulier que l'image de la transformation obtenue en intégrant des formes holomorphes sur les cycles linéaires de

ℙ_n\backslash ℙ_{n-p-1}

(avec

0 < p < n - 1

) est l'espace des fonctions holomorphes sur l'espace des cycles

\mathcal C_p(ℙ_n\backslash ℙ_{n-p-1})

, annulées par une famille d'opérateurs différentiels d'ordre quatre, que nous déterminons explicitement.
Méthodes à $N$ Corps pour un Problème de Milieux Pluristratifiés Perturbés
Authors: Dermenjian Yves , Iftimie Viorel
Published: January 2008

On étudie l'opérateur

H := ∇^*\rho ∇ + V

dans

L^2(X)

,

X

espace euclidien réel de dimension finie, oú

V

est un potentiel du type “

N

corps” associé à une famille finie

\mathscr L

de sous-espaces vectoriels de

X

et

\rho

admet une décomposition suivant

\mathscr L

compatible avec celle de

V

. Chaque composante de

V

, respectivement

\rho

, est une somme de perturbations de type “courte portée” et “longue portée”. En utilisant une variante de la méthode de Mourre [14] ainsi que des idées de la théorie du problème à

N

corps de la mécanique quantique, on fait l'analyse spectrale de l'opérateur

H

et on prouve un principe d'absorption limite.
Representations of the Quantum Toroidal Algebra on Highest Weight Modules of the Quantum Affine Algebra of Type $\mathfrak{gl}_N$
Authors: Takemura Kouichi , Uglov Denis
Published: January 2008

A representation of the quantum toroidal algebra of type

\mathfrak{sl}_N

is defined on every integrable irreducible highest weight module of the quantum affme algebra of type

\mathfrak{gl}_N

. The

q

-version of the level-rank duality giving the reciprocal decomposition of the

q

-Fock space with respect to mutually commutative actions of

U'q(\mathfrak{gl}_N)

of level

L

and

U'_q(\mathfrak{sl}_L)

of level

N

is described.
Some Limit Transitions between $BC$ Type Orthogonal Polynomials Interpreted on Quantum Complex Grassmannians
Authors: Dijkhuizen Mathijs S. , Stokman Jasper V.
Published: January 2008

The quantum complex Grassmannian

U_q/K_q

of rank

l

is the quotient of the quantum unitary group

U_q = U_q(n)

by the quantum subgroup

K_q = U_q(n–l) x U_q(l)

. We show that

(U_q, K_q)

is a quantum Gelfand pair and we express the zonal spherical functions, i.e.

K_q

-biinvariant matrix coefficients of finite-dimensional irreducible representations of

U_q

, as multivariable little

q

-Jacobi polynomials depending on one discrete parameter. Another type of biinvariant matrix coefficients is identified as multivariable big

q

-Jacobi polynomials. The proof is based on earlier results by Noumi, Sugitani and the first author relating Koornwinder polynomials to a one-parameter family of quantum complex Grassmannians, and certain limit transitions from Koornwinder polynomials to multivariable big and little

q

-Jacobi polynomials studied by Koornwinder and the second author.
Polynomial Weyl Representations
Authors: Robinson Paul Lee
Published: January 2008

For the canonical commutation relations in infinite dimensions, we offer an explicit direct construction of Weyl representations generated from the Fock representation by polynomial transformations of arbitrary degree, solving a problem posed by Proksch, Reents and Summers. Our solution employs new approaches to Hilbert–Schmidt polynomials and their Wick ordering.
$\mathscr D$-Modules Associated to the Group of Similitudes
Authors: Nang Philibert
Published: January 2008

We classify regular holonomic

\mathscr D

-modules whose characteristic variety is the union of the conormal bundles of the orbits of the group of similitudes of a non degenerate quadratic form.
Existence Theorems for Ordered Variants of Weyl Quantization
Authors: Dubin Daniel A. , Hennings Mark A. , Smith Thomas B.
Published: January 2008

We consider some mathematical properties of Weyl-like quantizations based on two families of orderings of

e^{t(αP+δQ)}

: the first family,

W_{(λ,0)}

interpolates between Wick (

λ = 1

) and antiWick (

λ = –1

) ordering, while the second family,

W_{(0,μ)}

, interpolates between the

Q^-

(

μ=1

) and

P^-

(

μ=–1

) orderings. The ordering

W_{(0,0)}

common to both families is the unordered Weyl system.

The most important property is that of the existence of quantizations. For all orderings

W_{(0,μ)}

and for

W_{(λ,0)}

with

–1 ≤ λ ≤ 0

quantization is a well-defined map from the tempered distributions on phase space into the continuous linear operators from

\mathscr S(ℝ)

into

\mathscr S(ℝ)'

. For the orderings

W_{(λ,0)}

with

–1 ≤ λ ≤ 0

we have to restrict the class of wave functions from

\mathscr S(ℝ)

to a certain dense subset of it, and the resulting quantization procedure sends tempered distributions on phase space into sesquilinear forms on this subspace. For Wick ordering itself we have not been able to find any useable quantization scheme, and we doubt whether any one exists that is based on tempered distributions.

We also consider questions of boundedness, and determine the matrix coefficients for the quantizations of phase space functions of radius or of angle. In particular, we consider various quantizations of the angle function in phase space.
Infinite Differentiability of Hermitian and Positive $C$-Semigroups and $C$-Cosine Functions
Authors: Li Yuan-Chuan , Shaw Sen-Yen M.
Published: January 2008

Let

C

be a bounded linear operator which is not necessarily injective. The following statements are proved: (1) hermitian

C

-semigroups are infinitely differentiable in operator norm on

(0, ∞)

; (2) hermitian

C

-cosine functions are norm continuous at either non or all of points in

[0, ∞)

; (3) positive

C

-semigroups which dominate

C

are infinitely differentiable in opetator norm on

[0, ∞)

; (4) positive

C

-cosine functions are infinitely differentiable in operator norm on

[0, ∞)

.
Dequantization Techniques for Weyl Quantization
Authors: Hennings Mark A. , Dubin Daniel A. , Smith Thomas B.
Published: January 2008

By quantization we mean the linear bijection from

\mathscr S'(\Pi)

to

\mathscr L(\mathscr S(ℝ)), \mathscr S'(ℝ))

due to Weyl, and by dequantization we mean its inverse. We propose two new, but related, dequantization schemes. The first is adapted to knowledge of the matrix elements (with respect to the Hermite–Gaussian functions) of the operator to be dequantized, while the second is adapted to its integral kernel. Our dequantization schemes are completely general. We apply these methods to the case where the operators in question are Toeplitz operators related to functions of angle on phase space. This enables us to compare the symbols of these Toeplitz operators with the functions of angle themselves.
Gevrey Wellposedness of the Cauchy Problem for the Hyperbolic Equations of Third Order with Coefficients Depending Only on Time
Authors: Kinoshita Tamotu
Published: January 2008

We shall show the Gevrey wellposedness of the Cauchy problem for the hyperbolic equations of third order with coefficients depending only on time. For the proof we use the suitable energy of the third order equations.
Algèbre Homologique des $N$-Complexes et Homologie de Hochschild aux Racines de l'Unité
Authors: Kassel Christian , Wambst Marc
Published: January 2008

We set up a homological algebra for

N

-complexes, which are graded modules together with a degree

-1

endomorphism

d

satisfying

d^N = 0

. We define

\operatorname{Tor}

- and

\operatorname{Ext}

-groups for

N

-complexes and we compute them m terms of their classical counterparts (

N = 2

) As an application, we get an alternative définition of thé Hochschild homology of an associative algebra out of an

N

-complex whose differential is based on a primitive

N

-th root of unity.

Nous développons une algèbre homologique pour les

N

-complexes, c'est-à-dire pour des modules gradues mums d'un endomorphisme d de degré

-1

tel que

d^N=0

. Dans ce cadre nous
définissons des groupes

\operatorname{Tor}

et

\operatorname{Ext}

que nous calculons en fonction des groupes

\operatorname{Tor}

et

\operatorname{Ext}

classiques
(

N= 2

). Comme application, nous obtenons l'homologie de Hochschild d'une algèbre associative
comme l'homologie d'un

N

-complexe dont la différentielle s'exprime à l'aide d'une racine primitive

N

-ième de l'unité.
Images Directes de Fibrés en Droites Adjoints
Authors: Mourougane Christophe
Published: January 2008

Our main purpose is to study ampleness and positivity properties of the direct image

φ\star L

of a holomorphic line bundle

L

under a smooth morphism

φ: X → Y

between compact complex analytic manifolds. We show that in general the ampleness of

L

does not imply that of the direct image

φ \star L

but only that of thé direct image of the adjoint line bundle

φ\star (K_{X/Y} \otimes L)

.
Representations of Hermitian Kernels by Means of Krein Spaces
Authors: Constantinescu Tiberiu , Gheondea Aurelian
Published: January 2008

Hermitian kernels are studied as generalizations of kernels of positive type. The main tool is the axiomatic concept of induced Krem space. The existence of Kolmogorov decompositions of a hermitian kernel and their uniqueness, modulo unitary equivalence, are characterized. The existence of reproducing kernel Krein spaces is shown to be equivalent to the existence of Kolmogorov decompositions. Applications Applications to the Naimark dilations of Toeplitz hermitian kernels on the set of integers and to the uniqueness of the Krem space completions of nondegenerate inner product spaces are included.
On the Thomae Formula for $\mathbf Z_N$ Curves
Authors: Nakayashiki Atsushi
Published: January 2008

We shall give an elementary and rigorous proof of the Thomae formula for

\mathbf Z_N

curves which was discovered by Bershadsky and Radul [1, 2]. Instead of using the determinant of the Laplacian we use the traditional variational method which goes back to Riemann, Thomae, Fuchs. In the proof we made explicit the algebraic expression of the chiral Szego kernels and prove the vanishing of zero values of derivatives of theta functions with

\mathbf Z_N

invariant

1/2N

characteristics.
A Family of Rank-2 Mathematical Instanton Bundles on $P_3$
Authors: Vedernikov Valery
Published: January 2008

A big family of rank-2 mathematical instanton bundles on the three-dimensional complex projective space

P_3

is constructed.
The Cut-Off Phenomenon for Random Walks on Hamming Graphs with Variable Growth Conditions
Authors: Hora Akihito
Published: January 2008

The cut-off phenomenon is a remarkable critical phenomenon observed in the process of convergence to equilibrium in a wide variety of Markov chains. Diaconis–Graham–Morrison [3] established the first precise evaluation around the critical time for Ehrenfests' urn model concerning

2

urns and

d

balls, i.e. nearest neighbor random walks on hypercube

\mathbf Z^d

. They showed that deviation from the equilibrium state is described well by using the error functiƒon. In this article, we work out the evaluation around the critical time for simple random walks on Hamming graphs

H(d,n)

, which coincide with an extended Ehrenfests' urn model concerning

n

urns and

d

balls. In our case, not only

d

but also

n

can grow in several manners. If

n/d

tends to

0

, the similar result to [3] remains valid and microscopic deviation from the equilibrium state is described by the error function. If

n/d

tends to a nonzero constant, however, it is shown that the error function has to be replaced by an expression involving Poisson distributions.
Scattering Theory for Elastic Wave Propagation Problems in Perturbed Stratified Media II
Authors: Shimizu Senjo
Published: January 2008

We consider a self-adjoint operator governing the propagation of elastic waves in stratified media

\boldsymbol R^3

, where Lame functions and a density are perturbed in a compact region. In this paper we prove the existence, the completeness, and the invariance principle of wave operators associated with the self-adjoint operator and a self-adjoint operator governing the propagation of elastic waves in unperturbed stratified media

\boldsymbol R^3

. The proof is based on an abstract scattering theory due to M. S. Birman.
The Mumford-Tate Conjecture for Drinfeld-Modules
Authors: Pink Richard
Published: January 2008

Consider the Galois representation on the Tate module of a Drinfeld module over a finitely generated field in generic characteristic. The main object of this paper is to determine the image of Galois in this representation, up to commensurability. We also determine the Dirichlet density of the set of places of prescribed reduction type, such as places of ordinary reduction.
Short Time Asymptotic Behaviour and Large Deviation for Brownian Motion on Some Affine Nested Fractals
Authors: Kumagai Takashi
Published: January 2008

We study so called Varadhan type short time asymptotic estimates of heat kernels and Shilder type large deviation for Brownian motion on some affme nested fractals introduced in [7]. As a corollary to our approach, we obtain sharper estimates of heat kernels for a class of one dimensional diffusion processes studied in [8].