Air pollution attributable postneonatal infant mortality in U.S. metropolitan areas: a risk assessment study

BACKGROUND: The impact of outdoor air pollution on infant mortality has not been quantified. METHODS: Based on exposure-response functions from a U.S. cohort study, we assessed the attributable risk of postneonatal infant mortality in 23 U.S. metropolitan areas related to particulate matter <10 μm in diameter (PM(10)) as a surrogate of total air pollution. RESULTS: The estimated proportion of all cause mortality, sudden infant death syndrome (normal birth weight infants only) and respiratory disease mortality (normal birth weight) attributable to PM(10 )above a chosen reference value of 12.0 μg/m(3 )PM(10 )was 6% (95% confidence interval 3–11%), 16% (95% confidence interval 9–23%) and 24% (95% confidence interval 7–44%), respectively. The expected number of infant deaths per year in the selected areas was 106 (95% confidence interval 53–185), 79 (95% confidence interval 46–111) and 15 (95% confidence interval 5–27), respectively. Approximately 75% of cases were from areas where the current levels are at or below the new U.S. PM(2.5 )standard of 15 μg/m(3 )(equivalent to 25 μg/m(3 )PM(10)). In a country where infant mortality rates and air pollution levels are relatively low, ambient air pollution as measured by particulate matter contributes to a substantial fraction of infant death, especially for those due to sudden infant death syndrome and respiratory disease. Even if all counties would comply to the new PM(2.5 )standard, the majority of the estimated burden would remain. CONCLUSION: Given the inherent limitations of risk assessments, further studies are needed to support and quantify the relationship between infant mortality and air pollution

The mechanism of oxygen isotope fractionation during N2O production by denitrification

The isotopic composition of soil-derived N2O can help differentiate between N2O production pathways and estimate the fraction of N2O reduced to N2. Until now, δ18O of N2O has been rarely used in the interpretation of N2O isotopic signatures because of the rather complex oxygen isotope fractionations during N2O production by denitrification. The latter process involves nitrate reduction mediated through the following three enzymes: nitrate reductase (NAR), nitrite reductase (NIR) and nitric oxide reductase (NOR). Each step removes one oxygen atom as water (H2O), which gives rise to a branching isotope effect. Moreover, denitrification intermediates may partially or fully exchange oxygen isotopes with ambient water, which is associated with an exchange isotope effect. The main objective of this study was to decipher the mechanism of oxygen isotope fractionation during N2O production by denitrification and, in particular, to investigate the relationship between the extent of oxygen isotope exchange with soil water and the δ18O values of the produced N2O. We performed several soil incubation experiments. For the first time, ∆17 O isotope tracing was applied to simultaneously determine the extent of oxygen isotope exchange and any associated oxygen isotope effect. We found bacterial denitrification to be typically associated with almost complete oxygen isotope exchange and a stable difference in δ18O between soil water and the produced N2O of δ18O(N2O / H2O) = (17.5±1.2) ‰. However, some experimental setups yielded oxygen isotope exchange as low as 56 % and a higher δ18O(N2O / H2O) of up to 37‰. The extent of isotope exchange and δ18O(N2O / H2O) showed a very significant correlation (R2 = 0.70, p < 0.00001). We hypothesise that this observation was due to the contribution of N2O from another production process, most probably fungal denitrification. An oxygen isotope fractionation model was used to test various scenarios with different magnitudes of branching isotope effects at different steps in the reduction process. The results suggest that during denitrification the isotope exchange occurs prior to the isotope branching and that the mechanism of this exchange is mostly associated with the enzymatic nitrite reduction mediated by NIR. For bacterial denitrification, the branching isotope effect can be surprisingly low, about (0.0±0.9) ‰; in contrast to fungal denitrification where higher values of up to 30‰ have been reported previously. This suggests that δ18O might be used as a tracer for differentiation between bacte- 5 rial and fungal denitrification, due to their different magnitudes of branching isotope effect

Oxygen isotope fractionation during N2O production by soil denitrification

The isotopic composition of soil-derived N₂O can help differentiate between N₂O production pathways and estimate the fraction of N₂O reduced to N₂. Until now, <i>δ</i>¹⁸O of N₂O has been rarely used in the interpretation of N₂O isotopic signatures because of the rather complex oxygen isotope fractionations during N₂O production by denitrification. The latter process involves nitrate reduction mediated through the following three enzymes: nitrate reductase (NAR), nitrite reductase (NIR) and nitric oxide reductase (NOR). Each step removes one oxygen atom as water (H₂O), which gives rise to a branching isotope effect. Moreover, denitrification intermediates may partially or fully exchange oxygen isotopes with ambient water, which is associated with an exchange isotope effect. The main objective of this study was to decipher the mechanism of oxygen isotope fractionation during N₂O production by soil denitrification and, in particular, to investigate the relationship between the extent of oxygen isotope exchange with soil water and the <i>δ</i>¹⁸O values of the produced N₂O. <br><br> In our soil incubation experiments Δ¹⁷O isotope tracing was applied for the first time to simultaneously determine the extent of oxygen isotope exchange and any associated oxygen isotope effect. We found that N₂O formation in static anoxic incubation experiments was typically associated with oxygen isotope exchange close to 100 % and a stable difference between the ¹⁸O ∕ ¹⁶O ratio of soil water and the N₂O product of <i>δ</i>¹⁸O(N₂O ∕ H₂O)  =  (17.5 ± 1.2) ‰. However, flow-through experiments gave lower oxygen isotope exchange down to 56 % and a higher <i>δ</i>¹⁸O(N₂O ∕ H₂O) of up to 37 ‰. The extent of isotope exchange and <i>δ</i>¹⁸O(N₂O ∕ H₂O) showed a significant correlation (<i>R</i>² = 0.70, <i>p</i> &lt;  0.00001). We hypothesize that this observation was due to the contribution of N₂O from another production process, most probably fungal denitrification. <br><br> An oxygen isotope fractionation model was used to test various scenarios with different magnitudes of branching isotope effects at different steps in the reduction process. The results suggest that during denitrification, isotope exchange occurs prior to isotope branching and that this exchange is mostly associated with the enzymatic nitrite reduction mediated by NIR. For bacterial denitrification, the branching isotope effect can be surprisingly low, about (0.0 ± 0.9) ‰, in contrast to fungal denitrification where higher values of up to 30 ‰ have been reported previously. This suggests that <i>δ</i>¹⁸O might be used as a tracer for differentiation between bacterial and fungal denitrification, due to their different magnitudes of branching isotope effects

Vývoj nových syntéz kondenzovaných aromatických sloučenin

Diserta ní práce je rozd lena do dvou ástí zam ených na syntézu a fotofyzikální analýzu dvou skupin strukturn p íbuzných látek: (i) 9,9'-spirobifluoren (SBFs) a (ii) dispiroindeno[2,1-c]fluoren (DS-IFs). (i) V první ásti byla vyvinuta nová p tikroková syntéza SBFs, kde klí ovým krokem byla Rh-komplexy katalyzovaná [2+2+2] cyklotrimerizace symetricky i nesymetricky substituovaných diyn alkohol s alkyny. Optimalizací této reakce (katalyzátor, teplota, as, rozpoušt dlo atd.) byly nalezeny ideální podmínky pro p ípravu 1,2,3,4-substituovaných fluorenol (klí ové intermediáty) a jako nejefektivn jší se ukázal být Wilkinson v katalyzátor (RhCl(PPh3)3). Tyto r zn substituované fluorenoly byly následn ve dvou krocích p evedeny na 19 nových SBFs, u kterých byl zkoumán vliv substituentu (elektronakceptorní, elektrondonorní) v poloze 4 na jejich spektroskopické vlastnosti. Získaná data ukazují emisní maxima em v rozsahu 315 až 389 nm s excelentními kvantovými výt žky s (až 1). (ii) V druhé ásti byla tato nová metoda pro p ípravu SBFs aplikována na p ípravu DS-IFs. Rh-katalyzovaná [2+2+2] cyklotrimerizace triyndiol poskytla indeno[2,1- c]fluorendioly ve vysokých výt žcích. Tyto byly op t ve dvou krocích p evedeny na odpovídající DS-IFs. Celkem bylo p ipraveno 9 symetricky substituovaných DS-IFs (pozice 6 a 7) a...This work is divided into two parts that are focused on the synthesis and assessment of photophysical properties of two structurally related compounds: (i) 9,9'-spirobifluorenes (SBFs) and (ii) dispiroindeno[2,1-c]fluorenes (DS-IFs). (i) In the first part, a five-step synthetic approach to SBFs was developed and as the crucial step was used an intermolecular [2+2+2] cyclotrimerization of symmetrically or unsymmetrically substituted diynols with alkynes catalyzed by Rh-complexes. Catalyst screening showed that Wilkinson's catalyst (RhCl(PPh3)3) had the highest efficiency in yielding 1,2,3,4-substituted fluorenols - the key intermediates. The fluorenols were then converted into SBFs bearing various electron-donating and -withdrawing groups, aromatic substituents, and -extended aromatic hydrocarbon moieties (PAHs). Altogether 19 different SBFs were prepared and their photophysical properties screened. The fluorescent emission maxima em were in the range of 315-389 nm with excellent quantum yields s (up to 1.00). As far as the substituent effect is concerned the presence of electron-withdrawing substituents on the SBF scaffold results in the red-shift of the emission maxima. (ii) In the second part, a similar synthetic strategy was applied for synthesis DS-IFs. In this instance was utilized again the...Katedra organické chemieDepartment of Organic ChemistryFaculty of SciencePřírodovědecká fakult

The Underlying Cause of Unpredictability in Exchange Rates and Good Models of Exchange Rate Regime Selection: Field and Laboratory Evidence

Variance of exchange rates around predictions can be from 1) undiscovered fundamentals, 2) efficient markets, 3) destabilising speculation, or 4) regime and personality differences in the heuristics used in the stage of evaluating alternatives. Field and experimental evidence identifies 4) as the underlying cause. Variance effects prior to the resolution of risk damage macroeconomic management but are excluded by expected utility theory wherein utilities attach only to the segment of the outcome flow after risk is passed. To include the evaluation stage and such damage from variance, the authorities can use models within SKAT, the Stages of Knowledge Ahead Theory

Water Balance Changes and Responses of Ecosystems and Society in the Berlin-Brandenburg Region – a Review

The climate change debate has increased the need for knowledge on both long- and short-term regional environmental changes. In general, these changes may often be a product of multiple causes, which complicates the separation of single driving forces. In this review we focus on current water budget changes in Germany’s capital region, Berlin-Brandenburg, over the last 30 years. Available studies from a variety of disciplines (e.g. hydrology, water engineering, landscape ecology, nature conservation) were analysed in order to (1) identify both local and regional hydrological changes, (2) reveal their potential causes, and (3) discuss responses of ecosystems and society. These studies show that the Berlin-Brandenburg region is widely characterised by decreasing groundwater recharge, leading to decreasing groundwater and lake levels as well as decreasing fluvial discharge. These trends result both from complex, regional human impacts (e.g. long-term effects of hydro-melioration and changes in forest composition) and more general climate warming. The observed and assumed (future) changes of the regional water balance have been creating, and will continue to create, multifaceted impacts on existing ecosystems and society (e.g. wetland drying, decrease of biodiversity, decrease of productivity of grasslands and forests, increasing conflicts of interests). Several efforts to respond to the regional water deficit problem have already been undertaken, comprising for instance land-use optimisation, wetland restoration measures and the reestablishment of mixed deciduous forests. In general, however, the reviewed regional material on this topic reveals that the number and complexity of empirical studies are still poor. Thus, for both the identification and the explanation of current water balance changes and their effects, as well as for development and implementation of adaptive strategies, further multidisciplinary research efforts at different scales, including interregional comparisons, are required. Furthermore, both the observation of hydrological changes and the evaluation of adaptive and mitigative responses require at least continuous or, even better, extended monitoring efforts

Spatial Effects of Technological Innovations and Changing Ways of Life

Die Forschergruppe A-II befasst sich mit den Wechselwirkungen zwischen technologischen und sozialen Veränderungen und mit der Dynamik von Mensch- Umwelt-Interaktionen. Der Schwerpunkt liegt hierbei auf der Untersuchung der Genese raumbezogener wie auch raumwirksamer Erfindungen (Keramikproduktion, Tierdomestikation, frühe Rad- und Wagentechnologie, Zugtiernutzung, frühes Hirtentum, Reiternomadismus) und den Mechanismen der Verbreitung dieser Innovationen. Hierbei gilt es zu untersuchen, inwiefern der zentrale Aspekt der räumlichen und sozialen Mobilität einerseits als Folge bestimmter technologischer Innovationen und andererseits als Voraussetzung für die Verbreitung von Innovationen angesehen werden kann. Darüber hinaus werden an mehreren Orten im eurasischen Steppenraum und in Zentralasien die weitreichenden Auswirkungen technologischer Innovationen auf demographische, soziale, ökonomische und räumliche Parameter in verschiedenen Projekten untersucht. Zum Einsatz kommen dabei sowohl archäologische Ausgrabungen unter Hinzuziehung naturwissenschaftlicher Verfahren aus den Bereichen Geophysik, Archäozoologie, Paläoethnobotanik, Pedologie und Geomorphologie als auch reine Laboranalysen an menschlichen und tierischen Zähnen und Knochen, zur Erhebung von isotopenchemischen Daten. Als theoretische Grundlagen wurden und werden in der Forschergruppe insbesondere die zentralen Begriffe Innovation, Mobilität und Wissen diskutiert

Einfache Synthese des 1.2-Dihydro-pentalens und seiner Substitutionsprodukte

Wahrend die Thermolyse von 6-(4-Amino-1,3-butadienyl)-fulvenen Azulene liefert [¹], führt die entsprechende Reaktion von 6-(2-Amino-vinyl)fulvenen ( I ) erwartungsgemäß nicht zum gewünschten, thermisch vermutlich sehr labilen Pentalen (2) [²]

Eine einfache Synthese von 1,5-Dihydropentalenen

Dihydropentalene haben als Vorstufen für eine Synthese des Pentalens und dessen Derivaten Bedeutung[¹]

Zur Kenntnis des Pentalens, 2-Methylpentalens und 1,3-Dimethylpentalens

Von den drei nicht-alternierenden bicyclischen Kohlenwasserstoffen Pentalen (1), Azulen (2)[¹] und Heptalen (3)[²] widerstand (1) im Gegensatz zu (2) und (3) trotz jahrzehntelanger Bemühungen allen Syntheseversuchen[³]