Counting degree-constrained subgraphs and orientations

The goal of this short paper to advertise the method of gauge transformations (aka holographic reduction, reparametrization) that is well-known in statistical physics and computer science, but less known in combinatorics. As an application of it we give a new proof of a theorem of A. Schrijver asserting that the number of Eulerian orientations of a $d$--regular graph on $n$ vertices with even $d$ is at least $\left(\frac{\binom{d}{d/2}}{2^{d/2}}\right)^n$. We also show that a $d$--regular graph with even $d$ has always at least as many Eulerian orientations as $(d/2)$--regular subgraphs

Prehistorical archaeomagnetic directions from Hungary in comparison with those from south-eastern Europe

Since the beginning of the modern archaeomagnetic investigations in Hungary in the nineteen seventies, some directional data of various prehistorical ages have also accumulated beside a larger body of the historical results. These are presented here and compared with 1) coeval directional results which are available from south-eastern Europe, its well as 2) the predictions of geomagnetic field directions for Hungary of the global geomagnetic field model, CALS7K.2. The comparison with the South-eastern European data has lead to new archaeomagnetic dates for one of the studied archaeological features which are thought to be an improvement to the presently accepted radiometric dates

COMPUTER SIMULATION OF POLYSILICON EMITTER TRANSISTORS

In this paper, a one-dimensional model is proposed to analyse heavy doped emitters of transistors being contacted with polycrystalline silicon (polysilicon). This model is based on the Effective Recombination Velocity (ERV) approach. The effect of the polysilicon contact in Poly silicon Emitter Transistors (PETs) can be modelled as a reduced surface recombination velocity for minority carriers and the increased series emitter resistance for majority carriers. Computer simulation has been used to predict the performance of the transistor. It is pointed out that the interface between polysilicon and silicon affects the value of the current density rather than the polysilicon itself. The other physical and technological parameters, to be chosen around their reasonable values, are used as fitting parameters to simulate the real performance of the PET cited in the literature

Paleomagnetic correlation of Miocene pyroclastics of the Bükk Mts and their forelands

Abstract Paleomagnetic measurements were carried out on 163 independently oriented samples from 19 sites of the Bükk Mts and their northern, western and southern forelands. The aim was to correlate the sites with one of three Miocene rhyolite tuff horizons using the combination of paleomagnetic marker horizons (rotational events) and traditional magnetostratigraphy. In contrast to the results of earlier studies in the southern Bükk foreland, which yielded only reversed polarity magnetizations, nearly half of the presently obtained paleomagnetic directions are of normal polarity. By their declinations they mostly belong to the middle tuff horizon, and only one belongs to the upper. The paleomagnetic age assignment of the studied sites sometimes supports one or both of the classifications of Balogh (1964) and Pelikán et al. (2005). However, about one-third of the sites classified by these authors as upper or lower tuffs were shown to belong to the middle tuff complex

The absorption spectrum of hydrogenated silicon carbide nanocrystals from ab initio calculations

The electronic structure and absorption spectrum of hydrogenated silicon carbide nanocrystals (SiCNC) have been determined by first principles calculations. We show that the reconstructed surface can significantly change not just the onset of absorption, but the \emph{shape} of the spectrum at higher energies. We found that the absorption treshold of the reconstructed SiCNs cannot be accurately predicted from traditional density functional theory calculations.Comment: 4 pages, 3 figures, 1 tabl

Transport of Pollutants around a High Building: Integrated Magnetic, Mineralogical and Geochemical Study

We studied the degree and distribution of traffic induced pollution at a 40 m high building at the side of a major road in Budapest by making magnetic, mineralogical and geochemical analysis on settled dust samples collected at different levels and at the front and back sides of the building. We observed strong seasonal dependence of the amounts of anthropogenic pollutants, which were highest during summer. This season was also characterized by strong vertical variation of the amounts of dust, of the magnetic susceptibilities (reflecting best the traffic induced pollution) and of the concentrations of Pb. All these have maximum values at 9 m, on both sides of the building. The pattern of the distribution does not correspond to what is predicted by an air flow model published for high buildings with similar morphology and wind conditions

Munkaattitűdök időbeli változása és nemzetközi összehasonlítása = Temporal changes in work attitudes and international comparison

Az OTKA által támogatott T 46648 számú kutatás a munkával összefüggő lakossági attitűdök vizsgálatára irányult. A kutatás a nemzetközi ISSP program részeként két szinten folyt: 1) a munkával kapcsolatos attitűdök időbeli változása Magyarországon; 2) a munkával kapcsolatos hazai attitűdök nemzetközi összevetése más országok adataival. Az időbeli változások tekintetében három időpontra (1989, 1997, 2005) vonatkozóan rendelkeztünk mérésekkel. Vizsgáltuk munka jellemzőit mind a fontosság, mind az adottság szempontjából. Mindhárom időpontra ezek sorrendje a következő volt: állásbiztonság, magas kereset, jó előrejutási lehetőség, érdekes munka, önálló munka, társadalmilag hasznos munka, másoknak segítő munka. Egy következő kérdéskör arra irányult, hogy milyen tényezők számítsanak akkor, amikor a dolgozók keresetét meghatározzák a munkáltatók. Itt arra a következtetésre jutottunk, hogy a nem szorosan vett teljesítmény alapú tényezők szerepe relatíve erősödött a munkabérek megállapításával kapcsolatban. A nemzetközi összehasonlítás esetében a szükséges SPSS file-ok csak 2007-ben érkeztek meg a nemzetközi adatbankból. Itt így a munka első, leíró fázisa zárult le a kutatási periódusban. Eszerint Magyarország a munkával kapcsolatos attitűdök szempontjából nem tekinthető extrém országnak. A magyar eredmények általában közelebb vannak más volt szocialista országok eredményeihez, mint a régebbi piacgazdasági országokban mérhető attitűdökhöz. | The research supported by OTKA (Ref. No. T 46648) targeted the investigation of population attitudes towards work orientation. The research was part of the ISSP program and has been carried out on two levels: 1) Temporal changes in the attitudes towards work orientation; 2) The comparison of the attitudes in Hungary to those in other countries. Regarding temporal changes, data are available for three points in time (1989, 1997, 2005). Work characteristics have been investigated both on for expectations and for actuality. Their rank order did not change for the three time points: job safety, high income, opportunities for advancement, interesting work, independent work, usefulness for the society, work that helps to others. Legitimacy of factors determining peoples' earning was a next focus of research. The results indicate that factors connected less to achievement have gained more importance for Hungary over time. For the international comparison, the Data Achieve made available the SPSS files. This made possible a first, descriptive analysis in the present phase of the research. This indicates that Hungary is not an extreme case for the work attitudes in international comparison. Generally speaking, the Hungarian results are closer to those in other former socialist nations than to those in the older market economies

Online voluntary mentoring: Optimising the assignment of students and mentors

After the closure of the schools in Hungary from March 2020 due to the pandemic, many students were left at home with no or not enough parental help for studying, and in the meantime some people had more free time and willingness to help others in need during the lockdown. In this paper we describe the optimisation aspects of a joint NGO project for allocating voluntary mentors to students using a web-based coordination mechanism. The goal of the project has been to form optimal pairs and study groups by taking into the preferences and the constraints of the participants. In this paper we present the optimisation concept, and the integer programming techniques used for solving the allocation problems. Furthermore, we conducted computation simulations on real and generated data for evaluate the performance of this dynamic matching scheme under different parameter settings