Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 7 de 7
Filtrar
Más filtros










Base de datos
Asunto principal
Intervalo de año de publicación
1.
Proc Natl Acad Sci U S A ; 121(3): e2307008121, 2024 Jan 16.
Artículo en Inglés | MEDLINE | ID: mdl-38215187

RESUMEN

Concern over democratic erosion has led to a proliferation of proposed interventions to strengthen democratic attitudes in the United States. Resource constraints, however, prevent implementing all proposed interventions. One approach to identify promising interventions entails leveraging domain experts, who have knowledge regarding a given field, to forecast the effectiveness of candidate interventions. We recruit experts who develop general knowledge about a social problem (academics), experts who directly intervene on the problem (practitioners), and nonexperts from the public to forecast the effectiveness of interventions to reduce partisan animosity, support for undemocratic practices, and support for partisan violence. Comparing 14,076 forecasts submitted by 1,181 forecasters against the results of a megaexperiment (n = 32,059) that tested 75 hypothesized effects of interventions, we find that both types of experts outperformed members of the public, though experts differed in how they were accurate. While academics' predictions were more specific (i.e., they identified a larger proportion of ineffective interventions and had fewer false-positive forecasts), practitioners' predictions were more sensitive (i.e., they identified a larger proportion of effective interventions and had fewer false-negative forecasts). Consistent with this, practitioners were better at predicting best-performing interventions, while academics were superior in predicting which interventions performed worst. Our paper highlights the importance of differentiating types of experts and types of accuracy. We conclude by discussing factors that affect whether sensitive or specific forecasters are preferable, such as the relative cost of false positives and negatives and the expected rate of intervention success.


Asunto(s)
Problemas Sociales , Estados Unidos , Predicción
2.
Med Princ Pract ; 2023 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-37549659

RESUMEN

Background The relationship between overweight or obesity and low back pain (LBP) has previously been investigated. Several recent studies have focused on the relationship between other indicators of obesity, particularly indicators of fat and the risk of LBP. However, the results of body composition and LBP have been inconsistent. Methods All data for the present retrospective, cross-sectional study was extracted from the Korea National Health and Nutrition Examination Survey (KNHANES) versions V-1 and 2 conducted in 2010 and 2011 by the Korean Centers for Disease Control and Prevention. In KNHANES V-1 (2010) and V-2 (2011), those over 50 years of age completed the surveys on LBP, body weight, and body composition assessed using dual-energy X-ray absorptiometry (DXA) were included. The multivariable logistic regression analysis was used to examine the relationship between the presence of chronic LBP and body composition adjusting for confounders. Results We analyzed 3,579 persons who completed the question. In the multivariable analyses adjusting for age and sex, none of the variables, including fat mass and fat-free mass, remained positively or negatively associated with LBP. Additionally, when depression, smoking, alcohol intake, physical activity, diabetes mellitus, and fat or lean tissue mass were included in the multivariable logistic model, no significant associations were found between all measures of fat mass, fat-free mass, and LBP Conclusion This study is contrary to previous studies that concluded that there is a correlation between obesity and fat mass and LBP. LBP is not associated with increased levels of obesity and fat mass.

3.
Proc Natl Acad Sci U S A ; 120(23): e2301836120, 2023 06 06.
Artículo en Inglés | MEDLINE | ID: mdl-37252992

RESUMEN

There is substantial concern about democratic backsliding in the United States. Evidence includes notably high levels of animosity toward out-partisans and support for undemocratic practices (SUP) among the general public. Much less is known, however, about the views of elected officials-even though they influence democratic outcomes more directly. In a survey experiment conducted with state legislators (N = 534), we show that these officials exhibit less animosity toward the other party, less SUP, and less support for partisan violence (SPV) than the general public. However, legislators vastly overestimate the levels of animosity, SUP, and SPV among voters from the other party (though not among voters from their own party). Further, those legislators randomly assigned to receive accurate information about the views of voters from the other party reported significantly lower SUP and marginally significantly lower partisan animosity toward the other party. This suggests that legislators' democratic attitudes are causally linked to their perceptions of other-party voters' democratic attitudes. Our findings highlight the importance of ensuring that office holders have access to reliable information about voters from both parties.

4.
Nanoscale Res Lett ; 9(1): 295, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-24982606

RESUMEN

A scattering layer is utilized by mixing nanoporous spheres and nanoparticles in ZnO-based dye-sensitized solar cells. Hundred-nanometer-sized ZnO spheres consisting of approximately 35-nm-sized nanoparticles provide not only effective light scattering but also a large surface area. Furthermore, ZnO nanoparticles are added to the scattering layer to facilitate charge transport and increase the surface area as filling up large voids. The mixed scattering layer of nanoparticles and nanoporous spheres on top of the nanoparticle-based electrode (bilayer geometry) improves solar cell efficiency by enhancing both the short-circuit current (J sc) and fill factor (FF), compared to the layer consisting of only nanoparticles or nanoporous spheres.

5.
Nanotechnology ; 24(36): 365604, 2013 Sep 13.
Artículo en Inglés | MEDLINE | ID: mdl-23958555

RESUMEN

A facile and straightforward method is suggested to synthesize nanoporous-TiO2 thin films for dye-sensitized solar cells (DSSCs). Silver/TiO2 co-sputtering led to the formation of nanocomposite films which consisted of silver nanoclusters with surrounding TiO2 matrices, and metal particles were subsequently etched by just immersing in nitric acid. Nanoporous-TiO2 DSSCs fabricated by this simple and effective process showed power-conversion efficiencies of up to 3.4% at a thickness of only 1.8 µm, which is much superior to that of conventional nanoparticulate-TiO2 DSSCs with similar thickness.

6.
Nanoscale Res Lett ; 7(1): 672, 2012 Dec 12.
Artículo en Inglés | MEDLINE | ID: mdl-23234569

RESUMEN

The effects of surface passivation on the photoluminescence (PL) properties of CdS nanoparticles oxidized by straightforward H2O2 injection were examined. Compared to pristine cadmium sulfide nanocrystals (quantum efficiency ≅ 0.1%), the surface-passivated CdS nanoparticles showed significantly enhanced luminescence properties (quantum efficiency ≅ 20%). The surface passivation by H2O2 injection was characterized using X-ray photoelectron spectroscopy, X-ray diffraction, and time-resolved PL. The photoluminescence enhancement is due to the two-order increase in the radiative recombination rate by the sulfate passivation layer.

7.
Nanoscale Res Lett ; 7(1): 482, 2012 Aug 29.
Artículo en Inglés | MEDLINE | ID: mdl-22931230

RESUMEN

The photoluminescence behavior of CdS quantum dots in initial growth stage was studied in connection with an annealing process. Compared to the as-synthesized CdS quantum dots (quantum efficiency ≅ 1%), the heat-treated sample showed enhanced luminescence properties (quantum efficiency ≅ 29%) with a narrow band-edge emission. The simple annealing process diminished the accumulated defect states within the nanoparticles and thereby reduced the nonradiative recombination, which was confirmed by diffraction, absorption, and time-resolved photoluminescence. Consequently, the highly luminescent and defect-free nanoparticles were obtained by a facile and straightforward process.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...