1,703 research outputs found
Verification of CPT-invariance of QED bound states for the production of muonium or antimuonium in scattering of electrons or positrons by nuclei
A possibility of a verification of CPT-invariance of QED for bound states by
example of muonium or antimuonium produced in reactions of scattering of
electrons or positrons by nuclei is considered. The number of events of the
muonium production is estimated for contemporary accelerators. The method of
the detection of muonium by measuring of oscillations of the decay curve caused
by the interference between the ground and excited state of muonium is
suggested. The admixture of the excited muonium to the final state is
calculated.Comment: 7 pages, 3 figures, Latex, published in JETP 74, 196 (2001),
corrected mistypes in eqs. (2.2), (2.4), (2.7
Monellin (MNEI) at 1.15 Å resolution
The crystal structure of the sweet protein MNEI at 1.15 Å resolution reveals networks of alternate conformations and stably bound negative ions
Electron electric dipole moment experiment using electric-field quantized slow cesium atoms
A proof-of-principle electron electric dipole moment (e-EDM) experiment using
slow cesium atoms, nulled magnetic fields, and electric field quantization has
been performed. With the ambient magnetic fields seen by the atoms reduced to
less than 200 pT, an electric field of 6 MV/m lifts the degeneracy between
states of unequal mF and, along with the low (approximately 3 m/s) velocity,
suppresses the systematic effect from the motional magnetic field. The low
velocity and small residual magnetic field have made it possible to induce
transitions between states and to perform state preparation, analysis, and
detection in regions free of applied static magnetic and electric fields. This
experiment demonstrates techniques that may be used to improve the e-EDM limit
by two orders of magnitude, but it is not in itself a sensitive e-EDM search,
mostly due to limitations of the laser system.Comment: 9 pages, 8 figures, accepted for publication in Phys. Rev.
Situational analysis of nutritional status among 1899 children presenting with cleft lip and/or palate in Indonesia
BACKGROUND: Given the increased risk of malnutrition in children with cleft lip and/or palate (CLP), determining their nutritional status is critical for preventing adverse surgical risks. However, no such disaggregated, national-level data are available in Indonesia. We aimed to determine the nutritional status of patients with clefts in Indonesia and to identify problems and solutions for malnutrition cases within the population.METHODS: In this cross-sectional study, we considered records of individuals who underwent primary surgery for CLP in Smile Train-sponsored facilities in Indonesia between 1 January 2016 and 31 December 2021 (n = 18 480). We only included children under the age of five with an evaluation date prior to admission date and excluded subjects with invalid data values. We classified their nutritional status by z-scores according to the World Health Organization Child Growth Standard (2006). Malnutrition cases cover four indicators - stunting, wasting, underweight, and overweight. We compared the prevalence for malnutrition cases in children under the age of five using national health survey data.RESULTS: We included 1899 records following data validation. The national prevalence of stunting (24.4%), wasting (12.5%), and overweight cases (12.9%) was high, while underweight cases (6.8%) were comparatively low. Statistical analyses showed significant differences in nutritional status based on length/height-for-age between girls and boys aged 0-5 months (P = 0.008) and 48-60 months (P = 0.001), and based on body mass index-for-age (P = 0.000) between girls and boys aged 0-5 months. Girls in different age groups exhibited a statistically significant difference in nutritional status based on length/height-for-age (P = 0.002) and weight-for-age (P = 0.017). Concurrent stunting and overweight were the most common forms of concurrent malnutrition (8.7%). We found a significant difference in the prevalence of underweight (P = 0.001) and overweight (P = 0.000) cases between children with CLP and those without CLP.CONCLUSIONS: Our findings highlight the importance of nutritional interventions for children with orofacial clefts in Indonesia, and the importance of age and gender in their design and implementation. Further investigation is necessary to explore the risks of overweight and concurrent malnutrition among this population.</p
Self-interest And Public Interest: The Motivations Of Political Actors
Self-Interest and Public Interest in Western Politics showed that the public, politicians, and bureaucrats are often public spirited. But this does not invalidate public-choice theory. Public-choice theory is an ideal type, not a claim that self-interest explains all political behavior. Instead, public-choice theory is useful in creating rules and institutions that guard against the worst case, which would be universal self-interestedness in politics. In contrast, the public-interest hypothesis is neither a comprehensive explanation of political behavior nor a sound basis for institutional design
Formaldehyde, glyoxal, and methylglyoxal in air and cloudwater at a rural mountain site in central Virginia
As part of the Shenandoah Cloud and Photochemistry Experiment (SCAPE), we measured formaldehyde (HCHO), glyoxal (CHOCHO), and methylglyoxal (CH3C(O)CHO) concentrations in air and cloudwater at Pinnacles (elevation 1037 m) in Shenandoah National Park during September 1990. Mean gas‐phase concentrations of HCHO and CHOCHO were 980 and 44 pptv, respectively. The concentration of CH3C(O)CHO rarely exceeded the detection limit of 50 pptv. Mean cloudwater concentrations of HCHO and CHOCHO were 9 and 2 μM, respectively; the mean CH3C(O)CHO concentration was below its detection limit of 0.3 μM. The maximum carbonyl concentrations were observed during stagnation events with high O3, peroxides, and CO. Outside of these events the carbonyls did not correlate significantly with O3, CO, or NOy. Carbonyl concentrations and concentration ratios were consistent with a major source for the carbonyls from isoprene oxidation. Oxidation of CH4 supplies a significant background of HCHO. The carbonyl concentrations were indistinguishable in two size fractions of cloudwater having a cut at d=18 μm. Gas‐ and aqueous‐phase concentrations of HCHO from samples collected during a nighttime cloud event agree with thermodynamic equilibria within a factor of 2. Samples collected during a daytime cloud event show HCHO supersaturation by up to a factor of 4. Positive artifacts in the cloudwater samples due to hydrolysis of hydroxymethylhydroperoxide (HOCH2OOH) could perhaps account for this discrepancy
Trimethylamine-N-oxide postprandial response in plasma and urine is lower after fermented compared to non-fermented dairy consumption in healthy adults
Trimethylamine-N-oxide (TMAO) can be produced by the gut microbiota from dietary substrates and is associated with cardiovascular disease. While dairy products contain TMAO precursors, the effect of fermented dairy on TMAO metabolism remains unclear. We used plasma and urine samples collected for two randomised cross-over studies to evaluate the effects of fermented dairy consumption on TMAO metabolism. In Study 1, thirteen healthy young men tested a yogurt and an acidified milk during postprandial tests and a two-week daily intervention. In Study 2, ten healthy adults tested milk and cheese during postprandial tests. TMAO and five related metabolites were measured in plasma and urine by LC-MS/MS and NMR. Faecal microbiota composition was assessed in Study 1 (16S rRNA metagenomics sequencing). Fermented milk products were associated with lower postprandial TMAO responses than non-fermented milks in urine (Study 1, p = 0.01; Study 2, p = 0.02) and in plasma, comparing yogurt and acidified milk (Study 1, p = 0.04). Daily consumption of dairy products did not differentially affect fasting TMAO metabolites. Significant correlations were observed between microbiota taxa and circulating or urinary TMAO concentrations. Fermentation of dairy products appear, at least transiently, to affect associations between dairy products and circulating TMAO levels
Ecosystem fluxes of hydrogen: a comparison of flux-gradient methods
Our understanding of biosphere–atmosphere exchange has been considerably enhanced by eddy covariance measurements. However, there remain many trace gases, such as molecular hydrogen (H[subscript 2]), that lack suitable analytical methods to measure their fluxes by eddy covariance. In such cases, flux-gradient methods can be used to calculate ecosystem-scale fluxes from vertical concentration gradients. The budget of atmospheric H[subscript 2] is poorly constrained by the limited available observations, and thus the ability to quantify and characterize the sources and sinks of H[subscript 2] by flux-gradient methods in various ecosystems is important. We developed an approach to make nonintrusive, automated measurements of ecosystem-scale H2 fluxes both above and below the forest canopy at the Harvard Forest in Petersham, Massachusetts, for over a year. We used three flux-gradient methods to calculate the fluxes: two similarity methods that do not rely on a micrometeorological determination of the eddy diffusivity, K, based on (1) trace gases or (2) sensible heat, and one flux-gradient method that (3) parameterizes K. We quantitatively assessed the flux-gradient methods using CO[subscript 2] and H[subscript 2]O by comparison to their simultaneous independent flux measurements via eddy covariance and soil chambers. All three flux-gradient methods performed well in certain locations, seasons, and times of day, and the best methods were trace gas similarity for above the canopy and K parameterization below it. Sensible heat similarity required several independent measurements, and the results were more variable, in part because those data were only available in the winter, when heat fluxes and temperature gradients were small and difficult to measure. Biases were often observed between flux-gradient methods and the independent flux measurements, and there was at least a 26% difference in nocturnal eddy-derived net ecosystem exchange (NEE) and chamber measurements. H[subscript 2] fluxes calculated in a summer period agreed within their uncertainty and pointed to soil uptake as the main driver of H[subscript 2] exchange at Harvard Forest, with H[subscript 2] deposition velocities ranging from 0.04 to 0.10 cm s[superscript −1].National Science Foundation (U.S.) (NSF Graduate Research Fellowship)United States. National Aeronautics and Space Administration (Advanced Global Atmospheric Gases Experiment (AGAGE))Massachusetts Institute of Technology. Joint Program on the Science & Policy of Global ChangeMartin Family Society of Fellows for SustainabilityMassachusetts Institute of Technology (Ally of Nature Research Fund)Massachusetts Institute of Technology (William Otis Crosby Lectureship)Massachusetts Institute of Technology (Warren Klein Fund
Power-Based Droop Control in DC Microgrids Enabling Seamless Disconnection From Upstream Grids
This paper proposes a local power-based droop controller for distributed energy resource converters in dc microgrids that are connected to upstream grids by grid-interface converters. During normal operation, the grid-interface converter imposes the microgrid bus voltage, and the proposed controller allows power flow regulation at distributed energy resource converters\u2019 output. On the other hand, during abnormal operation of the grid-interface converter (e.g., due to faults in the upstream grid), the proposed controller allows bus voltage regulation by droop control. Notably, the controller can autonomously convert from power flow control to droop control, without any need of bus voltage variation detection schemes or communication with other microgrid components, which enables seamless transitions between these two modes of operation. Considering distributed energy resource converters employing the power-based droop control, the operation modes of a single converter and of the whole microgrid are defined and investigated herein. The controller design is also introduced. Furthermore, the power sharing performance of this control approach is analyzed and compared with that of classical droop control. The experimental results from a laboratory-scale dc microgrid prototype are reported to show the final performances of the proposed power-based droop control
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