Comment on "Drought-induced reduction in global terrestrial net primary production from 2000 through 2009"     

Samanta A  Costa MH  Nunes EL  Vieira SA  Xu L  Myneni RB 《Science (New York, N.Y.)》2011,333(6046):1093; author reply 1093

Zhao and Running (Reports, 20 August 2010, p. 940) reported a reduction in global terrestrial net primary production (NPP) from 2000 through 2009. We argue that the small trends, regional patterns, and interannual variations that they describe are artifacts of their NPP model. Satellite observations of vegetation activity show no statistically significant changes in more than 85% of the vegetated lands south of 70°N during the same 2000 to 2009 period.  相似文献   

Climate change. Impacts research seen as next climate frontier     

Kintisch E 《Science (New York, N.Y.)》2008,322(5899):182-183

  相似文献   

Kinetics of morphogen gradient formation     

Kicheva A  Pantazis P  Bollenbach T  Kalaidzidis Y  Bittig T  Jülicher F  González-Gaitán M 《Science (New York, N.Y.)》2007,315(5811):521-525

In the developing fly wing, secreted morphogens such as Decapentaplegic (Dpp) and Wingless (Wg) form gradients of concentration providing positional information. Dpp forms a longer-range gradient than Wg. To understand how the range is controlled, we measured the four key kinetic parameters governing morphogen spreading: the production rate, the effective diffusion coefficient, the degradation rate, and the immobile fraction. The four parameters had different values for Dpp versus Wg. In addition, Dynamin-dependent endocytosis was required for spreading of Dpp, but not Wg. Thus, the cellular mechanisms of Dpp and Wingless spreading are different: Dpp spreading requires endocytic, intracellular trafficking.  相似文献   

Erasing the world's slow stain: strategies to beat multidrug-resistant tuberculosis     

Dye C  Williams BG  Espinal MA  Raviglione MC 《Science (New York, N.Y.)》2002,295(5562):2042-2046

Multidrug-resistant tuberculosis (MDR) is perceived as a growing hazard to human health worldwide. Judgments about the true scale of the problem, and strategies for containing it, need to come from a balanced appraisal of the epidemiological evidence. We conclude in this review that MDR is, and will probably remain, a locally severe problem; that epidemics can be prevented by fully exploiting the potential of standard short-course chemotherapy (SCC) based on cheap and safe first-line drugs; and that best-practice SCC may even reduce the incidence of MDR where it has already become endemic. On the basis of the available, imperfect data, we recommend a three-part response to the threat of MDR: widespread implementation of SCC as the cornerstone of good tuberculosis control, improved resistance testing and surveillance, and the careful introduction of second-line drugs after a sound evaluation of cost, effectiveness, and feasibility.  相似文献   

U.S. patent law. Case probes what's fair game in the search for new drugs     

Kintisch E 《Science (New York, N.Y.)》2005,308(5719):174

  相似文献   

Calling it something other than cloning     

Meyer E 《Science (New York, N.Y.)》2002,297(5578):51-2; author reply 51-2

  相似文献   

Ecology. Savannah River Lab faces budget ax     

Kintisch E 《Science (New York, N.Y.)》2005,307(5717):1857

  相似文献   

U.S. budget. Democratic Congress begins to put its stamp on science     

Kintisch E 《Science (New York, N.Y.)》2007,316(5833):1828-1829

  相似文献   

Effect of site and storage conditions on quality of industrial fresh pepper     

Marcos Guerra  Ricardo Magdaleno  Pedro A. Casquero 《Scientia Horticulturae》2011

The commercial expansion of roasted pepper as a high market value product have made that the period of time in which canning industries process the fresh pepper fruits needs to be extended. Fresh sweet pepper (Capsicum annuum L.) destined for industry grown in different sites was cold stored in order to analyse the effect of different sites and storage conditions on the quality of the product at harvest and during storage. Storage during 10 days at 8 °C was the best storage condition to improve quality of pepper destined for industry, because colour was improved, weight loss (1–1.6%) was lower than maximum permissible and decay incidence was only between 0% and 2.3%. Harvest should be delayed until pepper reaches the red state in order to increase the quality of the fruit. However, these results suggest that pepper growers should assure a high content of Ca (>0.6 g kg⁻¹) in the soil to avoid a high incidence of decay during storage when a late harvest is needed to guarantee the enhancement of colour in pepper fruit destined for industry. These storage conditions are in accordance with those found to improve the sensory quality of roasted pepper.  相似文献   

Do mature pine plantations resemble deciduous natural forests regarding understory plant diversity and canopy structure in historically modified landscapes?     

Reyes Tárrega  Leonor Calvo  Ángela Taboada  Elena Marcos  José Antonio Marcos 《European Journal of Forest Research》2011,130(6):949-957

We compared the structure of the arboreal layer and the diversity and species composition of the understory vegetation of three types of mature forest communities: oak (Quercus pyrenaica) and beech (Fagus sylvatica) forests and Scots pine (Pinus sylvestris) plantations. Our main aim was to determine whether differences in these variables existed and were due to the identity of the dominant tree species. We selected four stands or replicates per forest type located geographically close and with relatively similar conditions. We found no differences in the arboreal structure of oak and beech forests, which were characterised by great variability in tree size, while in case of plantations, this variability was lower at both the intra-stand (estimated by the coefficient of variation) and inter-stand (i.e. the four replicates harboured trees of similar sizes) scales. However, the highest variability in the canopy layer of natural forests was not consistently linked to greater understory species richness. Indeed, the lowest plant species richness was found in beech forests, while oak forests harboured the highest value at either the sampling unit (per m²) or stand scales. The greatest negative correlation between plant diversity and the environmental variables measured was found for litter depth, which was the highest in beech forests. The results obtained by the CCA indicated that the four replicates of each forest type clustered together, due to the presence of characteristic species. We concluded that pine plantations did not approach the environmental conditions of native forests, as plantations were characterised by singular understory species composition and low arboreal layer variability, compared to natural woodlands.  相似文献