Suchergebnisse

How has human activity hurt our rain forests? How has farming changed Earth's water cycle? How does carbon dioxide affect the climate? The exciting, eye-catching photographs and easy-to-read sentences in Natural Cycles and Climate Change help young readers learn how small changes in Earth's natural cycles can cause large and dangerous changes in Earth's climate. The book also has a helpful glossary and an index that direct students to the most important terms and topics.

In 2015, annual average atmospheric carbon dioxide (CO2) levels surpassed a level of 400 parts per million (ppm) for the first time in three million years. This has caused widespread concern among climate scientists, and not least among those that work on natural climate variability in prehistoric times, before humans. These people are known as 'past climate' or palaeoclimate researchers, and author Eelco J. Rohling is one of them. 'The Climate Question' offers a background to these concerns in straightforward terms, with examples, and is motivated by Rohling's personal experience in being intensely quizzed about whether modern change is not all just part of a natural cycle, whether nature will not simply resolve the issue for us, or whether it won't be just up to some novel engineering to settle things quickly.

AbstractTo compare pregnancy rate and implantation rate in poor responder women, aged over 40 years, who underwent natural cycle versus conventional ovarian stimulation. This is a retrospective single-center cohort study conducted at the GENERA IVF program, Rome, Italy, between September 2012 and December 2018, including only poor responder patients, according to Bologna criteria, of advanced age, who underwent IVF treatment through Natural Cycle or conventional ovarian stimulation. Between September 2012 and December 2018, 585 patients were included within the study. Two hundred thirty patients underwent natural cycle and 355 underwent conventional ovarian stimulation. In natural cycle group, both pregnancy rate per cycle (6.25 vs 12.89%, respectively, p = 0.0001) and pregnancy rate per patient101 with at least one embryo-transfer (18.85 vs 28.11% respectively, p = 0.025) resulted significant reduced. Pregnancy rate per patient managed with conventional ovarian stimulation resulted not significantly different compared with natural cycle (19.72 vs 15.65% respectively, p = 0.228), but embryo implantation rate was significantly higher in patients who underwent natural cycle rather than patient subjected to conventional ovarian stimulation (13 vs 8.28% respectively, p = 0.0468). No significant difference could be detected among the two groups in terms of abortion rate (p = 0.2915) or live birth pregnancy (p = 0.2281). Natural cycle seems to be a valid treatment in patients over 40 years and with a low ovarian reserve, as an alternative to conventional ovarian stimulation.

We examine whether governments' natural resource rents are affected by upcoming elections and if so, whether the incumbent uses these additional rents for re-election purposes. Estimates of a dynamic panel model for about 60 countries for 1975-2011 suggest that elections increase natural resource rents. The incumbent uses these rents for expanding public spending and reducing taxes before elections. However, these electoral cycle effects are statistically significant only in young democracies. Our results also suggest that election effects are stronger in countries with limited access to free media, limited political checks and balances, and a presidential system.

Although there are compelling theoretical reasons to believe that unequal political representation in a legislature leads to an unequal distribution of funds, testing such theories empirically is challenging because it is difficult to separate the effects of representation from the effects of either population levels or changes. We leverage the natural experiment generated by infrequent and discrete census apportionment cycles to estimate the distributional effects of malapportionment in the U.S. House of Representatives. We find that changes in representation cause changes in the distribution of federal outlays to the states. Our method is exportable to any democratic system in which reapportionments are regular, infrequent, and nonstrategic.

Electrocatalysis in Balancing the Natural Carbon Cycle Explore the potential of electrocatalysis to balance an off-kilter natural carbon cycle In Electrocatalysis in Balancing the Natural Carbon Cycle, accomplished researcher and author, Yaobing Wang, delivers a focused examination of why and how to solve the unbalance of the natural carbon cycle with electrocatalysis. The book introduces the natural carbon cycle and analyzes current bottlenecks being caused by human activities. It then examines fundamental topics, including CO2 reduction, water splitting, and small molecule (alcohols and acid) oxidation to prove the feasibility and advantages of using electrocatalysis to tune the unbalanced carbon cycle. You'll realize modern aspects of electrocatalysis through the operando diagnostic and predictable mechanistic investigations. Further, you will be able to evaluate and manage the efficiency of the electrocatalytic reactions. The distinguished author presents a holistic view of solving an unbalanced natural carbon cycle with electrocatalysis. Readers will also benefit from the inclusion of: A thorough introduction to the natural carbon cycle and the anthropogenic carbon cycle, including inorganic carbon to organic carbon and vice versa An exploration of electrochemical catalysis processes, including water splitting and the electrochemistry CO2 reduction reaction (ECO2RR) A practical discussion of water and fuel basic redox parameters, including electrocatalytic materials and their performance evaluation in different electrocatalytic cells A perspective of the operando approaches and computational fundamentals and advances of different electrocatalytic redox reactions Perfect for electrochemists, catalytic chemists, environmental and physical chemists, and inorganic chemists, Electrocatalysis in Balancing the Natural Carbon Cycle will also earn a place in the libraries of solid state and theoretical chemists seeking a one-stop reference for all aspects of electrocatalysis in carbon cycle-related reactions