A légkör fosszilis tüzelőanyagoktól származó CO2 tartalmának meghatározása 14C és CO2 koncentráció méréssel Magyarországon = Determination of fossil fuel originated CO2 content of air in Hungary by 14C and CO2 concentration measurements

Nagypontosságú légköri CO2 koncentráció és 14C méréseket együttesen használva Debrecenben, Magyarország egy átlagosan iparosodott régiójában, meghatároztuk a belváros levegőjének fosszilis tüzelőanyagokból származó CO2 tartalmát havi átlagokban 2008 szeptembere és 2010 márciusa között. A kutatás keretében világviszonylatban is egyedi, terepi mintavevő és mérőrendszert fejlesztettünk ki. Az újszerű mérési összeállítás analitikai teljesítőképességét összeméréssel igazoltuk. A természetes háttérszint megállapításához Magyarország dunántúli régiójában, Hegyhátsálon párhuzamos légköri 14CO2 méréseket indítottunk. A háttérállomás megfelelőségét több mint 100m szintkülönbséggel végzett párhuzamos mérések eredményeinek összehasonlításával igazoltuk. 2009. januárjában Debrecen levegőjében 10-15ppm tartományba eső tél közepi jól fejlett légköri fosszilis szén-dioxid csúcsot mutattunk ki, mely összhangban van a más, hasonló méretű európai városokban közölt adatokkal. 2008. és 2009. év októberében jelentős fosszilis szén-dioxid tartalom kiugrások mutatkoztak (10-17ppm) a vizsgált városi levegőben, melyekre a helyi meteorológiai viszonyok speciális alakulása vagy a biogén szén hatása adhat magyarázatot. A 2009. év telén gyakorlatilag nem volt kimutatható a tél közepi fosszilis CO2 maximum a debreceni levegőben. A városi fosszilis CO2 hányad eredményeinket a légköri CO2 minták szén stabilizotóp eredményei is megerősítették. | Between Sept 2008 and March 2010 we used combined atmospheric CO2 mixing ratio and 14C observations to estimate the monthly mean fossil fuel CO2 amount in the air of Debrecen city, which is located in a moderately industrial region of Hungary. In the framework of this study we developed an internationally unique field deployable monitoring station. The novel monitoring unit has been validated by inter-comparison measurements. To measure the Hungarian reference level we started simultaneous atmospheric 14CO2 observations near Hegyhátsál in the Transdanubian region of Hungary. The relevance of the reference location was demonstrated by two elevation measurements executed at the station in parallel but with more than 100m elevation difference. During January of 2009 we observed a well-developed monthly mean mid-winter atmospheric fossil fuel CO2 peak in Debrecen city with the amplitude of 10-15ppm which was in agreement with the winter data reported from other European cities. We also observed significant local maximums (10-17ppm) in atmospheric fossil fuel CO2 during October 2008 and 2009 in the city which possibly could be explained by more detailed study of local meteorological conditions and/or special biogenic CO2 effect. During the winter of 2009 we did not detect a mid-winter atmospheric fossil fuel CO2 peak in Debrecen city. Our urban fossil fuel CO2 records were also confirmed by the carbon stable isotope results of the collected atmospheric CO2 samples

What qualities do government-owned venture capital investors seek in a new venture? A comparison of investment criteria across pre-seed, seed, and expansion stage startups

Private venture capital (VC) investors usually do not invest in early life-cycle stage startups such as seed and pre-seed companies, since investment size typically doesn’t reach investment thresholds. The entry of governments with fund managers to venture capital markets presents seed and pre-seed companies with the opportunity to receive funding. This paper examines the main investment preferences of Hungarian government-owned venture capital investors regarding pre-seed, seed, and expansion stage startups. Verbal protocol analysis enabled examination of the screening process in real-time in all three life-cycle stages. It is found that governmental VC funds mostly value financial indicators followed by market-related qualities while private VCs value these characteristics in alternate formation. However, in the pre-seed stage, the financial acumen and capabilities of management teams form the main criteria in similarity to angel investors. Governmental VCs also greatly seek innovational value in target firms

High-precision loess chronologies by 14C-dating of small molluscs

Despite that loess records provide a wealth of information on abrupt climatic and environmental changes, almost all such records have low precision chronologies. Age-depth models of loess sequences have uncertainties reaching thousands of years thereby rendering proxy interpretations highly ambiguous on millennial/sub-millennial timescales. This is partly because OSL/IRSL dating techniques, commonly applied to eolian deposits, yield imprecise ages on such timescales. Also, 14C-dating of organic matter, secondary carbonates and humic acids provide questionable and mostly unreliable dates, for reasons not detailed here. At the same time, charcoals that are regarded as phases yielding reliable ages rarely occur in loess sequences and 14C-dates of molluscs are often anomalously old due to dead carbon incorporation during shell formation. Here we show that some species of molluscs having small (≦ 10 mm) shells incorporate very low amounts of 14C-deficient carbon into their shells and provide reliable ages as revealed by testing against charcoal ages and against a Bayesian age-depth model. 56 AMS radiocarbon ages were generated from a loess profile at Dunaszekcso (Hungary). Of these ages four originate from charcoals and are taken as reference. Comparison of mollusc shell ages with those of charcoals reveal that Succinella oblonga and Vitrea crystallina give statistically indistinguishable ages, while Chondrula tridens and Clausilia sp. shells show age anomalies ranging from 500 to 900 14C yr. Testing against a Bayesian age model resting on 48 14C ages at different depths (2-3 ages from each depth), highlights that, beyond S. oblonga and V. crystallina, species like Orcula dolium, Discus ruderatus, Euconulus fulvus, Pupilla muscorum and Vallonia costata yield relatively accurate ages (anomalies mostly within ±300 cal BP yr). This investigation also demonstrates that Trichia hispida is best avoided in 14C-dating studies and that micrographitization of shells, in case of low carbon contents after preparation, always results in anomalous ages