14,956 research outputs found
Dispelling the Anthropic Principle from the Dimensionality Arguments
It is shown that in d=11 supergravity, under a very reasonable ansatz, the
nearly flat spacetime in which we are living must be 4-dimensional without
appealing to the Anthropic Principle. Can we dispel the Anthropic Principle
completely from cosmology?Comment: 7 pages, Essa
B ->\eta_c K(\eta_c^\prime K) decays in QCD factorization
We study the exclusive decays of meson into pseudoscalar charmonium
states and within the QCD factorization approach and
find that the nonfactorizable corrections to naive factorization are infrared
safe at leading-twist order. The spectator interactions arising from the kaon
twist-3 effects are formally power-suppressed but chirally and logarithmically
enhanced. The theoretical decay rates are too small to accommodate the
experimental data. On the other hand, we compare the theoretical calculations
for , and , and find that the
predicted relative decay rates of these four states are approximately
compatible with experimental data.Comment: 8 pages, LaTex, 1 figure, one footnote and two references adde
Algorithms for Geometric Problems in Intensity-Modulated Radiation Therapy (Computational Geometry and Discrete Mathematics)
Agriculture is a major source of NO x pollution in California.
Nitrogen oxides (NO x = NO + NO2) are a primary component of air pollution-a leading cause of premature death in humans and biodiversity declines worldwide. Although regulatory policies in California have successfully limited transportation sources of NO x pollution, several of the United States' worst-air quality districts remain in rural regions of the state. Site-based findings suggest that NO x emissions from California's agricultural soils could contribute to air quality issues; however, a statewide estimate is hitherto lacking. We show that agricultural soils are a dominant source of NO x pollution in California, with especially high soil NO x emissions from the state's Central Valley region. We base our conclusion on two independent approaches: (i) a bottom-up spatial model of soil NO x emissions and (ii) top-down airborne observations of atmospheric NO x concentrations over the San Joaquin Valley. These approaches point to a large, overlooked NO x source from cropland soil, which is estimated to increase the NO x budget by 20 to 51%. These estimates are consistent with previous studies of point-scale measurements of NO x emissions from the soil. Our results highlight opportunities to limit NO x emissions from agriculture by investing in management practices that will bring co-benefits to the economy, ecosystems, and human health in rural areas of California
Optimization-Based Peptide Mass Fingerprinting for Protein Mixture Identification
*Motivation:* In current proteome research, peptide sequencing is probably the most widely used method for protein mixture identification. However, this peptide-centric method has its own disadvantages such as the immense volume of tandem Mass Spectrometry (MS) data for sequencing peptides. With the fast development of technology, it is possible to investigate other alternative techniques. Peptide Mass Fingerprinting (PMF) has been widely used to identify single purified proteins for more than 15 years. Unfortunately, this technique is less accurate than peptide sequencing method and cannot handle protein mixtures, which hampers the widespread use of PMF technique. If we can remove these limitations, PMF will become a useful tool in protein mixture identification. 
*Results:* We first formulate the problem of PMF protein mixture identification as an optimization problem. Then, we show that the use of some simple heuristics enables us to find good solutions. As a result, we obtain much better identification results than previous methods. Moreover, the result on real MS data can be comparable with that of the peptide sequencing method. Through a comprehensive simulation study, we identify a set of limiting factors that hinder the performance of PMF method in protein mixtures. We argue that it is feasible to remove these limitations and PMF can be a powerful tool in the analysis of protein mixtures
A study on the anticancer activity of ethanol extract of Aristolochia mollissima hance on osteosarcoma HOS cells
This paper mainly studied the extraction process of traditional Chinese medicine Aristolochia mollissima Hance (Aristolochiaceae) and the inhibitory effect of its extracts on osteosarcoma HOS cells. The extraction process included the ultrasonic extraction method, heat reflux method and decoction method to obtain three different extracts. MTT assay was used to test the effect of the extracts on proliferation of HOS cells, to compare the degree of inhibitory activity of three extracts, and to calculate cell survival rates. The results showed that among the three extracts obtained by the ultrasonic extraction method, heat reflux method and decoction method, the one obtained by ultrasonic extraction has the largest yield, but the extractobtained by heat reflux method has the strongest anticancer activity. Nevertheless, the three extracts all have a good inhibitory activity on theproliferation of osteosarcoma HOS cells.Key words: Aristolochia mollissima Hance; HOS cells; MTT; Anticance
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Extrapolation of point measurements and fertilizer-only emission factors cannot capture statewide soil NO x emissions.
Maaz et al. argue that inconsistencies across scales of observation undermine our working hypothesis that soil NO x emissions have been substantially overlooked in California; however, the core issues they raise are already discussed in our manuscript. We agree that point measurements cannot be reliably used to estimate statewide soil NO x emissions-the principal motivation behind our new modeling/airplane approach. Maaz et al.'s presentation of fertilizer-based emission factors (a nonmechanistic scaling of point measures to regions based solely on estimated nitrogen fertilizer application rates) includes no data from California or other semiarid sites, and does not explicitly account for widely known controls of climate, soil, and moisture on soil NO x fluxes. In contrast, our model includes all of these factors. Finally, the fertilizer sales data that Maaz et al. highlight are known to suffer from serious errors and do not offer a logically more robust pathway for spatial analysis of NO x emissions from soil
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