Small x gluon from exclusive J/psi production

Exclusive J/psi production, gamma* p -> J/psi p, offers a unique opportunity to determine the gluon density of the proton in the small x domain. We use the available HERA data to determine the gluon distribution in the region 10^{-4} <~ x <~ 10^{-2} and 2 <~ Q^2 <~ 10 GeV^2, where the uncertainty on the gluon extracted from the global parton analyses is large. The gluon density is found to be approximately flat at the lower scale; it is compared with those of recent global analyses.Comment: 13 pages, 5 figure

From Free Radicals and Spin-Chemistry Over Spin-Dynamics and Hyperpolarization to Biology and Materials Science

This special issue of ZPC is dedicated to the 80th anniversary of Kev Salikhov, a prominent scientist who has made seminal contributions to spin chemistry, chemical kinetics, spin hyperpolarization and magnetic resonance. Altogether there are 41 scientific papers; for this reason, the guest editors have decided to publish three subsequent issues. Each issue is focused on a particular field, which is closely related to research interests of Salikhov or was even seeded by his work. As the following papers clearly demonstrate, the initial seed of Salikhov fell on a very fruitful soil and has grown to a huge and impressive scientific tree with branches ranging from fundamental science to applications in biochemistry and materials science

The Evolution of Bulgarian Banks' Efficiency During the Twenties: A Dea Approach

This paper studies the dynamics of the bank efficiency in Bulgaria in the years 1923 and 1928. In the course of research several interdependencies were detected, related mainly to the reaction of different types of banks to the financial crisis and the financial stabilization. Official bank balance sheets were used as well as the profit and loss statements of 50 Bulgarian credit institutions. After their classification into subgroups different variations of DEA (data envelopment analysis), in particular the intermediation approach, were applied to the banks’ financial positions. The DEA overcomes several deficiencies in the traditional accounting measurement of bank efficiency, which has made it very popular in latest literature. To our knowledge this method has not been applied so far to historical data.Bulgarian monetary history; Banking system; Âanking efficiency; DEA modelling.

Effective exchange rates of the Bulgarian Lev 1879-1939

The paper constructs the first series of nominal and real effective exchange rates of the Bulgarian Lev from its establishment in 1879 until 1939. The dynamics of both indicators during the Classical Gold Standard fits the general picture of exchange rate development of other European countries while their movements in the Interwar years reflects the exchange rate policy of the monetary authority and the price effects of the Great Depression. The study also provides econometric estimation of the impact of the real effective exchange rates and foreign demand on Bulgaria’s real export performance allowing for some policy implications.

Can one improve the Froissart bound?

We explain why we hope that the Froissart bound can be improved, either qualitatively or, more likely, quantitatively, by making a better use of unitarity, in particular elastic unitarity. In other instances (Gribov's theorem) elastic unitarity played a crucial role. A preliminary requirement for this is to work with an appropriate average of the cross-section, to make the problem well defined. This is possible, without destroying the Lukaszuk--Martin bound.Comment: 4 pages, latex with AIP style, Talk given at "Diffraction 2008", Lalonde-les-Maures, France, September 2008. Missing square root restored p. 3. pi^2->pi corrected in eq. (1

A comparison of two magnetic ultra-cold neutron trapping concepts using a Halbach-octupole array

This paper describes a new magnetic trap for ultra-cold neutrons (UCNs) made from a 1.2 m long Halbach-octupole array of permanent magnets with an inner bore radius of 47 mm combined with an assembly of superconducting end coils and bias field solenoid. The use of the trap in a vertical, magneto-gravitational and a horizontal setup are compared in terms of the effective volume and ability to control key systematic effects that need to be addressed in high precision neutron lifetime measurements

On the Time-Evolution of Resonant Triads in Rotational Capillary-Gravity Water Waves

We investigate an effect of the resonant interaction in the case of one-directional propagation of capillary-gravity surface waves arising as the free surface of a rotational water flow. Specifically, we assume a constant vorticity in the body of the fluid which physically corresponds to an underlying current with a linear horizontal velocity profile. We consider the interaction of three distinct modes and we obtain the dynamic equations for a resonant triad. Setting the constant vorticity equal to zero we recover the well known integrable three-wave system

CHALLENGES OF MIGRANT FAMILIES FROM EASTERN MACEDONIA

Since its independence in 1991, the Republic of North Macedonia has faced a difficultprocess of transition, economic and political changes, continuous high unemployment ratesand an armed conflict. In addition, the processes of globalization, industrialization andurbanization, as well as the rapid advancement of digital technology and increased mobilityof the population, have contributed to numerous social changes that inevitably reflected onfamily structures and functions.Today, the modern Macedonian family is very dynamic and it is adapting to internaland external changes and challenges, whilst family members strive for better life qualityand conditions. In addition to internal migration from rural to urban areas in the country, inthe past decades there is an increased emigration from North Macedonia towards EuropeanUnion member states, as well as overseas countries. The region of Eastern Macedonia wasparticularly affected by the emigration of entire families, due for several reasons, the mostcommon of which are: high unemployment rates, poor economic conditions and politicalinstability in the country.In this paper we will present an analysis of the current situation in Eastern Macedonia,as well a research on the challenges faced by migrant families from the municipality of Vinica

The Ratio R=FL/FTR=F_L/F_T in DIS as a Probe of the Charm Content of the Proton

We analyze the Callan-Gross ratio $R(x,Q^2)=F_L/F_T$ in heavy-quark leptoproduction as a probe of the charm content of the proton. To estimate the charm-initiated contributions, we use the ACOT($\chi$) variable-flavor-number scheme. Our analysis shows that charm densities of the recent CTEQ sets of parton distributions have sizeable impact on the Callan-Gross ratio in a wide region of $x$ and $Q^2$. In particular, the ACOT($\chi$) predictions for the quantity $R(x,Q^2)$ are about half as large as the corresponding expectations of the photon-gluon fusion mechanism for $x\sim 10^{-2}-10^{-1}$ and $Q^2\gg m^2$. This is because the structure functions $F_T (x,Q^2)$ and $F_L (x,Q^2)$ have different dependences on the mass logarithms of the type $\alpha_{s}\ln(Q^{2}/m^{2})$. On the other hand, our recent studies indicate that, contrary to the production cross sections, the Callan-Gross ratio is sufficiently stable under radiative corrections to the photon-gluon fusion component for $x\gtrsim 10^{-4}$. We conclude that the quantity $R(x,Q^2)$ in heavy-quark leptoproduction is perturbatively stable but sensitive to resummation of the mass logarithms. For this reason, in contrast to the structure functions, the ratio $R(x,Q^2)=F_L/F_T$ could be good probe of the charm density in the proton.Comment: 10 pages, 4 figures, revtex