8,476 research outputs found
Federal Nutritional Guidance and the Politics of Science: A Tale of Regulatory Capture
This paper examines US government involvement in nutrition and agriculture. Specifically, it attempts to explain the existence of conflicting information presented by scientific versus government sources in the food pyramid. We start by examining the theory of the politicization of science and regulatory capture. We then examine federal nutrition advice through this theoretical framework. The paper concludes that the negative consequences of federal intervention for everyday Americans call for an alternative approach of decentralization, with an emphasis on private regulators, with government ticking to its core functions, rather than engaging in politicized favoritism
Network-constrained models of liberalized electricity markets: the devil is in the details
Numerical models for electricity markets are frequently used to inform and support decisions. How robust are the results? Three research groups used the same, realistic data set for generators, demand and transmission network as input for their numerical models. The results coincide when predicting competitive market results. In the strategic case in which large generators can exercise market power, the predicted prices differed significantly. The results are highly sensitive to assumptions about market design, timing of the market and assumptions about constraints on the rationality of generators. Given the same assumptions the results coincide. We provide a checklist for users to understand the implications of different modelling assumptions.Market power, Electricity, Networks, Numeric models, Model comparison
Nitro-Carba test, a novel and simple chromogenic phenotypic method for rapid screening of carbapeneamase-producing Enterobacteriaceae.
OBJECTIVES: The present study developed Nitro-Carba Test (NCT), a rapid and simple chromogenic method for screening of Carbapenemase-producing Enterobacteriaceae (CPE). METHODS: The NCT was validated with a total of 31 carbapenemase-producing isolates (9 KPCs, 11 MBLs and 11 OXA-48s) and with 56 non-carbapenemase-producing strains. The assay relies on the hydrolysis of nitrocefin in the presence of carbapenems. The carbapenemases were extracted with lysis buffer prior to addition to wells with and without imipenem (IPM), meropenem (MEM) and ertapenem (ETP). Following the addition of nitrocefin, a change in colour from yellow to red, indicating carbapenemase production, was observed within 20min. The susceptibility profiles of each bacterial strain were also investigated. RESULTS: A NCT detected all 31 CPEs within a timeframe of only 10seconds to 12min. All carbapenemase producers hydrolyzed nitrocefin in all wells. No colour change in the wells with carbapenems was observed in non-carbapenemase producers. The sensitivity for all three carbapenems was 100%, while specificity of IPM, MEM and ETP were 64.29%, 91.07% and 100%, respectively. IPM, MEM and ETP against all carbapenemase-producing strains had MIC values ranging from 0.5 to â„256ÎŒg/mL, 0.25 to â„256ÎŒg/mL and 1 to â„256ÎŒg/mL, respectively. OXA-48-producing isolates showed lower MIC values compared with producers of MBL and KPC. CONCLUSION: This assay is a promising method detecting CPE rapidly. The NCT is a simple and reliable method, capable of detecting CPE in even carbapenem-susceptible strains
Electron-Energy Loss of Ultraviolet Plasmonic Modes in Aluminum Nanodisks
We theoretically investigated electron energy loss spectroscopy (EELS) of
ultraviolet surface plasmon modes in aluminum nanodisks. Using full-wave
simulations, we studied the impact of diameter on the resonant modes of the
nanodisks. We found that the mode behavior can be separately classified for two
distinct cases: (1) flat nanodisks where the diameter is much less than the
thickness; and (2) thick nanodisks where the diameter is comparable to the
thickness. While the multipolar edge modes and breathing modes of flat
nanostructures have previously been interpreted using intuitive, analytical
models based on surface plasmon polariton (SPP) modes of a thin-film stack, it
has been found that the true dispersion relation of the multipolar edge modes
deviates significantly from the SPP dispersion relation. Here, we developed a
modified intuitive model that uses effective wavelength theory to accurately
model this dispersion relation with significantly less computational overhead
compared to full-wave electromagnetic simulations. However, for the case of
thick nanodisks, this effective wavelength theory breaks down, and such
intuitive models are no longer viable. We found that this is because some modes
of the thick nanodisks carry a polar (i.e. out of the substrate plane, or along
the electron beam direction) dependence and cannot be simply categorized as
radial breathing modes or angular (azimuthal) multipolar edge modes. This polar
dependence leads to radiative losses, motivating the use of simultaneous EELS
and cathodoluminescence measurements when experimentally investigating the
complex mode behavior of thick nanostructures
The performance of a resazurin chromogenic agar plate with a combined disc method for rapid screening of extended-spectrum-ÎČ-lactamases, AmpC ÎČ-lactamases and co-ÎČ-lactamases in Enterobacteriaceae.
A resazurin chromogenic agar (RCA) along with combined disc method has been developed as a promising method for rapid screening of extended-spectrum-ÎČ-lactamase (ESBL), AmpC ÎČ-lactamase, and co-production of ESBL and AmpC. Cefpodoxime (CPD) discs supplemented with and without clavulanic acid (CA), cloxacillin (CX), or CA+CX were evaluated against 86-molecularly confirmed ÎČ-lactamase-producing Enterobacteriaceae, including 15 ESBLs, 32 AmpCs, 9 co-producers of ESBL and AmpC, and 30 carbapenemase producers. The CA and CX synergy test successfully detected all ESBL producers (100% sensitivity and 98.6% specificity) and all AmpC producers (100% sensitivity and 96.36% specificity). This assay also exhibited a good performance in the screening for the co-existence of ESBL and AmpC (88.89% sensitivity and 100% specificity). The RCA assay is a simple and inexpensive method that allows observation of results within 7 h. It can be applicable in any microbiological laboratory, especially in the endemic areas of ESBL, AmpC, or co-ÎČ-lactamase-producing Enterobacteriaceae
A low upper-limit on the lithium isotope ratio in HD140283
We have obtained a high-S/N (900-1100), high-resolving-power (R=95000)
spectrum of the metal-poor subgiant HD 140283 in an effort to measure its
6Li/7Li isotope ratio. From a 1-D atmospheric analysis, we find a value
consistent with zero, 6Li/7Li = 0.001, with an upper limit of 6Li/7Li < 0.026.
This measurement supersedes an earlier detection (0.040 +/- 0.015(1sigma)) by
one of the authors. HD 140283 provides no support for the suggestion that
Population II stars may preserve their 6Li on the portion of the subgiant
branch where 7Li is preserved. However, this star does not defeat the
suggestion either; being at the cool end of subgiant branch of the Spite
plateau, it may be sufficiently cool that 6Li depletion has already set in, or
the star may be sufficiently metal poor that little Galactic production of 6Li
had occurred. Continued investigation of other subgiants is necessary to test
the idea. We also consider the implications of the HD 140283 upper limit in
conjunction with other measurements for models of 6Li production by cosmic rays
from supernovae and structure formation shocks.Comment: 8 pages, 4 figures; accepted for publication in Astronomy and
Astrophysic
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