University of New Hampshire

About: University of New Hampshire is a education organization based out in Durham, New Hampshire, United States. It is known for research contribution in the topics: Population & Solar wind. The organization has 9379 authors who have published 24025 publications receiving 1020112 citations. The organization is also known as: UNH.

Roots and fungi accelerate carbon and nitrogen cycling in forests exposed to elevated CO2.

Abstract: A common finding in multiple CO2 enrichment experiments in forests is the lack of soil carbon (C) accumulation owing to microbial priming of ‘old’ soil organic matter (SOM). However, soil C losses may also result from the accelerated turnover of ‘young’ microbial tissues that are rich in nitrogen (N) relative to bulk SOM. We measured root-induced changes in soil C dynamics in a pine forest exposed to elevated CO2 and N enrichment by combining stable isotope analyses, molecular characterisations of SOM and microbial assays. We find strong evidence that the accelerated turnover of root-derived C under elevated CO2 is sufficient in magnitude to offset increased belowground inputs. In addition, the C losses were associated with accelerated N cycling, suggesting that trees exposed to elevated CO2 not only enhance N availability by stimulating microbial decomposition of SOM via priming but also increase the rate at which N cycles through microbial pools.

Global Deforestation: Contribution to Atmospheric Carbon Dioxide

Abstract: A study of effects of terrestrial biota on the amount of carbon dioxide in the atmosphere suggests that the global net release of carbon due to forest clearing between 1860 and 1980 was between 135 x 10(15) and 228 x 10(15) grams. Between 1.8 x 10(15) and 4.7 x 10(15) grams of carbon were released in 1980, of which nearly 80 percent was due to deforestation, principally in the tropics. The annual release of carbon from the biota and soils exceeded the release from fossil fuels until about 1960. Because the biotic release has been and remains much larger than is commonly assumed, the airborne fraction, usually considered to be about 50 percent of the release from fossil fuels, was probably between 22 and 43 percent of the total carbon released in 1980. The increase in carbon dioxide in the atmosphere is thought by some to be increasing the storage of carbon in the earth's remaining forests sufficiently to offset the release from deforestation. The interpretation of the evidence presented here suggests no such effect; deforestation appears to be the dominant biotic effect on atmospheric carbon dioxide. If deforestation increases in proportion to population, the biotic release of carbon will reach 9 x 10(15) grams per year before forests are exhausted early in the next century. The possibilities for limiting the accumulation of carbon dioxide in the atmosphere through reduction in use of fossil fuels and through management of forests may be greater than is commonly assumed.

Bacterial glycosidases for the production of universal red blood cells

Abstract: Enzymatic removal of blood group ABO antigens to develop universal red blood cells ( RBCs) was a pioneering vision originally proposed more than 25 years ago. Although the feasibility of this approach was demonstrated in clinical trials for group B RBCs, a major obstacle in translating this technology to clinical practice has been the lack of efficient glycosidase enzymes. Here we report two bacterial glycosidase gene families that provide enzymes capable of efficient removal of A and B antigens at neutral pH with low consumption of recombinant enzymes. The crystal structure of a member of the alpha-N-acetylgalactosaminidase family reveals an unusual catalytic mechanism involving NAD(+). The enzymatic conversion processes we describe hold promise for achieving the goal of producing universal RBCs, which would improve the blood supply while enhancing the safety of clinical transfusions.

Pathways to poly-victimization.

Abstract: Some children, whom we have labeled poly-victims, experience very high levels of victimizations of different types. This article finds support for a conceptual model suggesting that there may be four distinct pathways to becoming such a poly-victim: (a) residing in a dangerous community, (b) living in a dangerous family, (c) having a chaotic, multiproblem family environment, or (d) having emotional problems that increase risk behavior, engender antagonism, and compromise the capacity to protect oneself. It uses three waves of the Developmental Victimization Survey, a nationally representative sample of children aged 2-17 years. All four hypothesized pathways showed significant independent association with poly-victim onset. For the younger children, the symptom score representing emotional problems was the only significant predictor. For the older children, the other three pathway variables were significant predictors--dangerous communities, dangerous families, and problem families--but not symptom score. Poly-victimization onset was also disproportionately likely to occur in the year prior to children's 7th and 15th birthday, corresponding roughly to the entry into elementary school and high school. The identification of such pathways and the ages of high onset should help practitioners design programs for preventing vulnerable children from becoming poly-victims. Language: en

Riverine nitrogen export from the continents to the coasts

Abstract: [1] We present an overview of riverine nitrogen flux calculations that were prepared for the International Nitrogen Initiative's current global assessment of nitrogen cycles: past, present, and future (Galloway et al., 2004). We quantified anthropogenic and natural inputs of reactive nitrogen (N) to terrestrial landscapes and the associated riverine N fluxes. Anthropogenic inputs include fossil-fuel derived atmospheric deposition, fixation in cultivated croplands, fertilizer use, and the net import in human food and animal feedstuffs. Natural inputs include natural biological N fixation in forests and other noncultivated vegetated lands, and fixation by lightning. We use an empirical model relating total N inputs per landscape area to the total flux of N discharged in rivers based on watershed data from contrasting ecosystems spanning multiple spatial scales. With this approach, we simulate riverine N loads to the coastal zone and to inland waters from the continents. Globally, rivers exported about 59 Tg N yr−1, with 11 Tg N yr−1 transported to dry lands and inland receiving waters, and 48 Tg N yr−1 transported to the coastal zone. Rates of riverine N loss vary greatly among the continents, reflecting the regional differences in population and the associated anthropogenic N inputs. We compare our estimates to other approaches that have been reported in the literature. Our work provides an understanding of the sources of N to landscapes and the associated N fluxes in rivers, and highlights how anthropogenic activities impact N cycling around the world.