A kinetic model for coagulation-fragmentation

The aim of this paper is to show an existence theorem for a kinetic model of coagulation-fragmentation with initial data satisfying the natural physical bounds, and assumptions of finite number of particles and finite $L^p$-norm. We use the notion of renormalized solutions introduced dy DiPerna and Lions, because of the lack of \textit{a priori} estimates. The proof is based on weak-compactness methods in $L^1$, allowed by $L^p$-norms propagation.Comment: 36 page

Rehabilitation of vowels in children after cochlear implantation

Sluh i slušanje sastavni su dio čovjekova razvoja i djelovanja od samog rođenja. Oni su ključni za uspješno usvajanje govora i jezika. Slušna oštećenja mogu spriječiti ili otežati uredan razvoj govora i stoga ih je važno dijagnosticirati rano, kako bi rehabilitacija mogla početi što je prije moguće zbog toga što su rane godine djetinjstva važne za razvoj ne samo govora i jezika nego za opći kognitivni razvoj i društvene vještine. Umjetna pužnica moderno je slušno pomagalo koje sve više zamjenjuje tradicionalna pomagala i daje bolje rezultate. Cilj ovog istraživanja bio je provjeriti kako djeca s umjetnom pužnicom tijekom rehabilitacije usvajaju govor, naročito samoglasnike/vokale. Također se htjelo ispitati ima li razlika u percepciji njihova govora između uvježbanih stručnjaka – fonetičara i laika. Pripremljena su dva kompleta sličica – jedan za dvoje djece starije od 5 godina i jedan za sedmero djece u dobi od 3 do 5 godina. Djeca su trebala reći koji su predmeti na svakoj slici i to je snimano. Snimke su potom prezentirane slušateljima fonetičarima i nefonetičarima, koji su tijekom slušanja trebali odgovoriti na nekoliko pitanja o djeci i njiovu govoru. Na temelju njihovih odgovora i akustičke analize vokala moglo se zaključiti da rehabilitacija daje zadovoljavajuće rezultate, naročito kad se radi o vokalima. Također se pokazalo da su fonetičari vještiji u zapažanju detalja i finih razlika među djecom i njihova općeg verbalnog ponašanja, ali da i nefonetičari mogu prepoznati i procijenit slušne i artikulacijske sposobnosti djece.Hearing and listening are integral parts of human development and fuctioning from the very beginning. They are crucial in speech and language acquisition. Hearing impairments can prevent typical speech development and it is therefore crucial that they be diagnosed early so that rehabilitation can start as soon as possible, because early years are important for the development of speech and language, cognitive abilities in general and social skills. Cochlear implants are modern hearing aids that increasingly replace conventional ones and have been shown to yield much better results. The aim of this study was to investigate how well children with cochlear implants acquire speech, particularly vowels, in the course of their rehabilitation. Another question was how is their speech perceived by listeners, trained phoneticians, on the one hand, and lay listeners. Two sets of pictures were compiled for this purpose, one for two children over the age 5, and one for 7 younger children aged between 3 and 5 years. After they had been recorded naming the presented pictures, two groups of listeners (trained phoneticians – university students of phonetics and university students of other programs) were asked to listen to the recordings and answer several questions about the children and their speech. Based on listeners’ responses and acoustic analyses it can be concluded that rehabilitation outcomes are satisfactory, particularly with respect to vowels. It was also found that trained phoneticians are more attentive to details in children’s speech and overall verbal behavior but that untrained listeners are also capable of dealing with children’s auditory and articulatory abilities

Scalar field localization on a brane with cosmological constant

We address the localization of a scalar field, whose bulk-mass M is considered in a wide range including the tachyonic region,on a three-brane. The brane with non-zero cosmological constant $\lambda$ is embedded in five dimensional bulk space. We find in this case that the trapped scalar could have mass $m$ which has an upper bound and expressed as $m^2=m_0^2+\alpha M^2\leq \beta |\lambda|$ with the calculable numbers $m_0^2, \alpha, \beta$. We point out that this result would be important to study the stability of the brane and cosmological problems based on the brane-world.Comment: 14 pages, 5 figure

Negative refraction in crystals with spatial dispersion

We predict, on the basis of numerical simulations, that organic crystals with appropriate spatial dispersion can exhibit negative refraction at optical frequencies near excitonic transitions. In particular we demonstrate that a plane slab of such materials is able to focus light coming from an oscillating point dipole. The intensity of the resulting image and its sharpness are mainly limited by absorption but its very presence unambiguously demonstrates negative refraction at the slab/vacuum interface. In our approach the medium is characterized by a generalized dielectric constant and all the relevant fields are computed by solving Maxwell equations with appropriate boundary conditions

Localization of Quantum Fields on Branes

A mechanism for localization of quantum fields on a $s$-brane, representing the boundary of a s+2 dimensional bulk space, is investigated. Minkowski and AdS bulk spaces are analyzed. Besides the background geometry, the relevant parameters controlling the theory are the mass M and a real parameter \eta, specifying the boundary condition on the brane. The importance of exploring the whole range of allowed values for these parameters is emphasized. Stability in Minkowski space requires \eta to be greater or equal to -M, whereas in the AdS background all real \eta are permitted. Both in the flat and in AdS case, the induced field on the brane is a non-canonical generalized free field. For a suitable choice of boundary condition, corresponding to the presence of a boundary state, the induced field on the brane mimics standard s+1 dimensional physics. In a certain range of \eta, the spectral function in the the AdS case is ominated by a massive excitation, which imitates the presence of massive particle on the brane. We show that the quantum field induced on the brane is stable.Comment: 17 pages, Latex, two eps figures. Few misprints corrected. Final version accepted for publication in Nuclear Physics

On the accretion disc properties in eclipsing dwarf nova EM Cyg

In this paper we analyzed the behavior of the unusual dwarf nova EM Cyg using the data obtained in April-October, 2007 in Vyhorlat observatory (Slovak Republic) and in September, 2006 in Crimean Astrophysical Observatory (Ukraine). During our observations EM Cyg has shown outbursts in every 15-40 days. Because on the light curves of EM Cyg the partial eclipse of an accretion disc is observed we applied the eclipse mapping technique to reconstruct the temperature distribution in eclipsed parts of the disc. Calculations of the accretion rate in the system were made for the quiescent and the outburst states of activity for different distances.Comment: 6 pages, 3 figures, accepted in Astrophysics and Space Scienc

Grand Unification Signal from Ultra High Energy Cosmic Rays?

The spectrum of ultrahigh energy (above \approx 10^{9} GeV) cosmic rays is consistent with the decay of GUT scale particles. The predicted mass is m_X=10^b GeV, where b=14.6_{-1.7}^{+1.6}.Comment: 4 pages, 3 figures one figure removed, one table added, conclusions essentially remained the same within errorbar

Получение и изучение углеродных нанотрубок.

Synthesis parameters of multiwall carbon nanotubes were prepared by catalytic pyrolysis of toluene and isopropyl alcohol under isochome conditions in the presence of nickel oxalate as catalyst were investigated. The synthesis products were analyzed by electron microscopy and x-ray diffraction spectroscopyИсследованы параметры синтеза многослойных углеродых нанотрубок при каталитическим пиролизе толуола и изопропанола в изохорических условиях с участием оксалата никеля. Полученные продукты исследовались с использованием методов электронной микроскопии и рентгеновского анализа

Determination of Oxidative Gelation Capacity of Wheat Flour Using Micro Visco-Amylo-Graph

Cilj ovog istraživanja bio je ispitati mogućnost primjene Mikro Visko-Amilografa (Brabender, Njemačka) u određivanju oksidacijke gelacijske sposobnosti (OGS) pšeničnog brašna kao i utvrđivanje eventualne korelacije s rezultatima ispitivanja retencijske sposobnosti brašna prema različitim otapalima (SRC) i s rezultatima kemijsko-reoloških analiza. U istraživanju je korišteno 12 uzoraka pšeničnog brašna T-550. Amilografska ispitivanja provedena su na suspenzijama brašna (40 g) i vode (80 ml) pri konstantnoj temperaturi (30 °C), a kako bi se odredio OGS nakon 20 min miješanja u suspenziju je dodavano 65 μL 3 %-tnog $H_{2}O_{2}$, a mjerenje je nastavljeno još 10 min. Na temelju dobivenih rezultata može se zaključiti da se amilografsko ispitivanje bez klasične primjene zagrijavanja, odnosno bez praćenja želatinizacije škroba, može uspješno primijeniti u određivanju viskoznosti suspenzija brašna. Primjenom amilografskih ispitivanja pri konstantnoj temperaturi (30 °C) i određivanjem retencijske sposobnosti brašna (SRC) može se predvidjeti jakost brašna i steći dublji uvid u kvalitativni profil uzoraka pšeničnog brašna. Dodatkom 3 %-tne otopine $H_{2}O_{2}$ može se odrediti oksidacijka gelacijska sposobnost, odnosno utvrditi potencijalni doprinos arabinoksilanske komponente viskoznosti suspenzije ili tijesta od pšeničnog brašna.The aim of this study was to investigate the possibility of using Micro Visco-Amylograph (Brabender, Germany) in determining the oxidative gelation capacity (OGC) of wheat flour, as well as to determine the possible correlation with the results of the solvent retention capacity (SRC) test and chemical and rheological analyses. Twelve samples of T-550 wheat flour were used in the study. Amylographic tests were performed on suspensions of flour (40 g) and water (80 ml) at constant temperature (30 ° C). After 20 min 65 μL of 3% $H_{2}O_{2}$ were added to the suspension to determine the OGS. Based on the obtained results, it can be concluded that amylographic testing, without the classical application of heating, can be successfully applied in determining the viscosity of flour suspensions. By applying amylographic tests at constant temperature (30 ° C) and determining the retention capacity of flour (SRC), the strength of the flour can be predicted and a deeper insight into the qualitative profile of wheat flour samples can be obtained. By addition of 3% $H_{2}O_{2}$ solution the oxidation gelation capacity can be determined, as well as the potential contribution of the arabinoxylan component to the viscosity of suspension or wheat dough