184 research outputs found
4-Methyl-2,6-bis(phosphonomethyl)phenol dihydrate
The 4-methyl-2,6-bis(phosphomethyl)phenol molecule,
which crystallizes with two water molecules per asymmetric
unit, has approximate twofold symmetry and is
involved in extensive three-dimensional hydrogen bonding
in which every available OH group participates.
The principal dimensions include P--O 1.4981 (13)
and 1.5015 (14) ,~, four P--OH distances in the range
1.5395(14) to 1.5688(13) A, P--C 1.7857(17) and
1.7893 (17) ~k, and O...O intramolecular and intermolecular
hydro.gen-bond distances in the range 2.458 (2) to
2.866 (2) A
Fructose Acute Effects on Glucose, Insulin, and Triglyceride After a Solid Meal Compared with Sucralose and Sucrose in a Randomized Crossover Study
Fructose, which is a sweetener with a low glycemic index, has been shown to elevate postprandial triglyceride compared with glucose. There are limited data on the effect of fructose in a solid mixed meal containing starch and protein.We determined the effects of sucrose, fructose, and sucralose on triglyceride, glucose, and insulin in an acute study in healthy, overweight, and obese individuals.The study had a randomized crossover design. Twenty-seven participants with a mean age of 44 y and a mean body mass index (in kg/m(2)) of 26 completed the study. Fructose (52 g), sucrose (65 g), and sucralose (0.1 g) were delivered as sweet-taste-balanced muffins with a total fat load (66 g). Blood samples were taken at baseline and every 30 min for 4-h glucose, triglyceride, and insulin concentrations, and the area under the curve (AUC) and the incremental area under the curve (iAUC) were analyzed.No significant difference was shown between the 3 sweeteners for triglyceride and glucose concentrations and the AUC. The glucose iAUC was lower for fructose than for sucrose and sucralose (P \u3c 0.05). Insulin concentrations differed significantly by the type of muffin (P = 0.001), the interaction of time by type of muffin (P = 0.035), the AUC (P \u3c 0.001), and the iAUC (P \u3c 0.001). Fructose had a significantly lower insulin response than that of either sucrose (P-treatment = 0.006) or sucralose (P-treatment = 0.041).Fructose, at a moderate dose, did not significantly elevate triglyceride compared with sucrose or sucralose and lowered the glucose iAUC. These results indicate that these sweeteners, at an equivalent sweetness, can be used in normal solid meals. Fructose showed a lower insulin response, which may be beneficial in the long term in individuals at risk of type 2 diabetes. This trial was registered at the Australian New Zealand Clinical Trials Registry as ACTRN12615000279527
Close to Uniform Prime Number Generation With Fewer Random Bits
In this paper, we analyze several variants of a simple method for generating
prime numbers with fewer random bits. To generate a prime less than ,
the basic idea is to fix a constant , pick a
uniformly random coprime to , and choose of the form ,
where only is updated if the primality test fails. We prove that variants
of this approach provide prime generation algorithms requiring few random bits
and whose output distribution is close to uniform, under less and less
expensive assumptions: first a relatively strong conjecture by H.L. Montgomery,
made precise by Friedlander and Granville; then the Extended Riemann
Hypothesis; and finally fully unconditionally using the
Barban-Davenport-Halberstam theorem. We argue that this approach has a number
of desirable properties compared to previous algorithms.Comment: Full version of ICALP 2014 paper. Alternate version of IACR ePrint
Report 2011/48
Assessing London CO2, CH4 and CO emissions using aircraft measurements and dispersion modelling
We present a new modelling approach for assessing atmospheric emissions from a city, using an aircraft measurement sampling strategy similar to that employed by previous mass balance studies. Unlike conventional mass balance methods, our approach does not assume that city-scale emissions are confined to a well-defined urban area and that peri-urban emissions are negligible. We apply our new approach to a case study conducted in March 2016, investigating CO, <span classCombining double low lineCH4 and <span classCombining double low lineCO2 emissions from a region focussed around Greater London using aircraft sampling of the downwind plume. For each species, we simulate the flux per unit area that would be observed at the aircraft sampling locations based on emissions from the UK national inventory, transported using a Lagrangian dispersion model. To reconcile this simulation with the measured flux per unit area, assuming the transport model is not biased, we require that inventory values of CO, <span classCombining double low lineCH4 and <span classCombining double low lineCO2 are scaled by 1.03, 0.71 and 1.61, respectively. However, our result for <span classCombining double low lineCO2 should not be considered a direct comparison with the inventory which only includes anthropogenic fluxes. For comparison, we also calculate fluxes using a conventional mass balance approach and compare these to the emissions inventory aggregated over the Greater London area. Using this method we derive much higher inventory scale factors for all three gases, as a direct consequence of the failure to account for emissions outside the Greater London boundary. That substantially different conclusions are drawn using the conventional mass balance method demonstrates the danger of using this technique for cities whose emissions cannot be separated from significant surrounding sources
Characterisation of the muon beams for the Muon Ionisation Cooling Experiment
A novel single-particle technique to measure emittance has been developed and used to characterise seventeen different muon beams for the Muon Ionisation Cooling Experiment (MICE). The muon beams, whose mean momenta vary from 171 to 281 MeV/c, have emittances of approximately 1.2â2.3 Ïâmm-rad horizontally and 0.6â1.0 Ïâmm-rad vertically, a horizontal dispersion of 90â190 mm and momentum spreads of about 25 MeV/c. There is reasonable agreement between the measured parameters of the beams and the results of simulations. The beams are found to meet the requirements of MICE
Airborne measurements of fire emission factors for African biomass burning sampled during the MOYA campaign
Airborne sampling of methane (CH4), carbon dioxide (CO2), carbon monoxide (CO), and nitrous oxide (N2O) mole fractions was conducted during field campaigns targeting fires over Senegal in February and March 2017 and Uganda in January 2019. The majority of fire plumes sampled were close to or directly over burning vegetation, with the exception of two longer-range flights over the West African Atlantic seaboard (100-300 km from source), where the continental outflow of biomass burning emissions from a wider area ofWest Africa was sampled. Fire emission factors (EFs) and modified combustion efficiencies (MCEs) were estimated from the enhancements in measured mole fractions. For the Senegalese fires, mean EFs and corresponding uncertainties in units of gram per kilogram of dry fuel were 1.8 ± 0.19 for CH4, 1633 ± 171.4 for CO2, and 67 ± 7.4 for CO, with a mean MCE of 0.94 ± 0.005. For the Ugandan fires, mean EFs were 3.1 ± 0.35 for CH4, 1610 ± 169.7 for CO2, and 78 ± 8.9 for CO, with a mean modified combustion efficiency of 0.93 ± 0.004. A mean N2O EF of 0.08 ± 0.002 gkg..1 is also reported for one flight over Uganda; issues with temperature control of the instrument optical bench prevented N2O EFs from being obtained for other flights over Uganda. This study has provided new datasets of African biomass burning EFs and MCEs for two distinct study regions, in which both have been studied little by aircraft measurement previously. These results highlight the important intracontinental variability of biomass burning trace gas emissions and can be used to better constrain future biomass burning emission budgets. More generally, these results highlight the importance of regional and fuel-type variability when attempting to spatially scale biomass burning emissions. Further work to constrain EFs at more local scales and for more specific (and quantifiable) fuel types will serve to improve global estimates of biomass burning emissions of climate-relevant gases
Diving into the vertical dimension of elasmobranch movement ecology
Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements
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