Energy positivity is established for a class of solutions to Einstein-aether theory and the IR limit of Hořava gravity within a certain range of coupling parameters. The class consists of solutions where the aether 4-vector is divergence-free on a spacelike surface to which it is orthogonal (which implies that the surface is maximal). In particular, this result holds for spherically symmetric solutions at a moment of time symmetry.
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http://dx.doi.org/10.1103/PhysRevLett.107.191102 | DOI Listing |
Langmuir
January 2025
Brigham Young University, Provo, Utah 84602, United States.
Accurate models for predicting drop dynamics, such as maximum drop departure sizes, are crucial for estimating heat transfer rates during condensation on superhydrophobic (SH) surfaces. Previous studies have focused on examining the heat transfer rates for SH surfaces under the influence of gravity or vapor flowing over the surface. This study investigates the impact of surface solid fraction and texture scale on drop mobility in a condensing environment with a humid air flow.
View Article and Find Full Text PDFPLoS One
January 2025
School of Economics and Trade, Hunan University, Changsha, China.
High trade costs pose substantial barriers to the process of trade liberalization. This study aims to measure trade costs and explore the driving forces behind the growth of bilateral trade between Cambodia and its top 30 trading partners from 1993 to 2019. Using a micro-founded measure of trade costs derived from the gravity model, we find that Cambodia's average trade costs decreased by 35.
View Article and Find Full Text PDFPLoS One
January 2025
College of Tourism, Hubei University, Wuhan, Hubei, China.
The study analyzed the spatial distribution characteristics, evolution rules, and driving factors of 138 China's national agricultural cultural heritage sites from 2013 to 2021 at the overall and regional levels, using kernel density analysis, Centres for standard deviation ellipse analyses, spatial autocorrelation analysis, and geographical detector analysis.The results showed that: ①From an overall perspective, the spatial pattern of China's national agricultural cultural heritage changed greatly from 2013 to 2021, with a highly uneven spatial distribution, gradually showing a distribution pattern of "widely distributed, locally concentrated". The spatial distribution of China's national agricultural cultural heritage is increasingly evident, and the spatial distribution type has evolved from discrete to clustered.
View Article and Find Full Text PDFAerosp Med Hum Perform
January 2025
Introduction: The introduction of fifth-generation fighter aircraft has raised concerns regarding the impact of high gravitational forces on lung function. This study aimed to investigate the acute effects of controlled +Gz exposure, up to +9 Gz, on lung function in military pilots using impulse oscillometry (IOS).
Methods: These studies, conducted in Canada and the Netherlands, involved military pilots undergoing high G centrifuge training.
Introduction: Space agencies will embark on manned journeys to Mars on smaller vehicles than those used previously. In-flight exercise on those flights must abate the adverse effects microgravity (μG) has on humans. Due to space constraints on these vehicles, a single exercise device must address multiple fitness needs.
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