A multicounter radiocarbon dating system was developed applying the experiences of the previous one-channel low-level counting facility. The counter system consists of nine electrolytic copper proportional counters of identical diameters with sensitive volumes of 0.35–0.7dm3 and filled with either methane at high pressure (6 bar) or CO2 at 1 bar. The inner counters are surrounded by an anticoincidence shield consisting of five multiwire proportional flat counters filled with propane. The pulses of the detectors are handled by integrated amplifiers, discriminators and anticoincidence units interfaced to a microprocessor-controlled data evaluation unit. Software is written in BASIC using ASSEMBLER sub-routines. The overall precision of the system for modern carbon samples using high-pressure methane-filled counters (B ≍ 0.7 cpm, S ≍ 14 cpm) is better than 4 after a counting period of seven days.

Background: Most current approaches in forest science and practice require information about structure and growth of individual trees rather than -or in addition to -sum and mean values of growth and yield at forest stand level as provided by classic experimental designs. By inventing the wheel design, Nelder provided the possibility to turn to the individual tree as basic information unit. Such trials provide valuable insights into the dependency of growth on stand density at particular sites.

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-Black locust (Robinia pseudoacacia L.) is one of the most important forest tree species in Hungary, covering approximately 23% of the forested land and providing 25% of the annual timber output of the country. One third of these black locust stands are high forests (planted with seedlings) and the remainder coppices. According to the forestry regulations black locust stands can be regenerated both by root suckers and with seedlings in Hungary. This study investigates the influence of different regeneration methods on wood production, stem quality and health. Properly managed regeneration from root suckers produced a higher yield than regeneration from seedlings at a harvest age of 35-37 years. The results show that regeneration of black locust stands from root suckers can be recommended on good and medium quality sites without a decrease in yield or stem quality. Robinia pseudoacacia L. / regeneration methods / yield / health conditionKivonat -Különböző felújítási módok hatása akácosok hozamára: esettanulmány. Az akác (Robinia pseudoacacia L.) az egyik legfontosabb állományalkotó fafaj Magyarországon, az erdőterület mintegy 23%-át borítja és az ország éves faanyag-termelésének 25%-át adja. Ezen akácállományok egyharmada szálerdő (mageredetű), a maradék pedig sarj eredetű. Magyarországon a szakmai előírások értelmében az akácosok magról és gyökérsarjról újíthatók fel. A dolgozat különböző felújítási módoknak a fatermésre, a törzsminőségre, illetve a fák egészségi állapotára gyakorolt hatását vizsgálja. A számított adatok szerint a gyökérsarjról történő szakszerű és gondos felújítás a 35-37 éves véghasználati korban magasabb hozamot eredményezett, mint a magról történő felújítás. A vizsgálati eredmények alapján az akácosok gyökérsarjról történő felújítása elsősorban a jó és közepes termőhelyeken ajánlott a fatermés csökkenése nélkül. Fehér akác / felújítási módok / fatermés / egészségi állapot

Light curve analysis of the carbon variable RY Dra and the oxygen-rich variables TX Dra and AF Cyg is summarised. In each case, two shorter periods were found (which may be connected with the radial pulsation of the stars) and also a long term variation in the mean brightness. In the case of RY Dra, the amplitudes of the shorter periods both decreased while the amplitude of the long secondary variation was found to be increasing. The light curves and frequency spectra of TX Dra and AF Cyg can be interpreted as a result of mode switching. These stars pulsate with two different periods and there are time intervals when the longer period disappears and the shorter one remains dominant, and it lasts for many cycles. We concluded that the double and multi-periodic red semiregular variables may be very important from both theoretical and observational point of view, because, based on the ratio of the periods, we can identify the pulsational modes in these variables.