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Sky cooling for LED streetlights

Thermal management is a critical challenge for semiconductor light-emitting diodes (LEDs), as inadequate heat dissipation reduces luminous efficiency and shortens the devices’ lifespan. Thus, there is an urgent need for more effective cooling strategies to enhance the energy efficiency of LEDs. LED streetlights, which operate primarily at night and experience high chip temperatures, could benefit greatly from improved thermal management. In this study, we introduce a sky-facing radiative cooling strategy for outdoor LED streetlights, an innovative yet less explored approach for thermal management of optoelectronics. Our method employs a nanoporous polyethylene (nanoPE) material that possesses both infrared transparency and visible reflectivity. This approach enables the direct release of heat generated by the LED through a sky-facing radiative cooling channel, while also reflecting a significant portion of the light back for illumination. By incorporating nanoPE as a cover for sky-facing LED lights, we achieved a remarkable temperature reduction of 7.8 °C in controlled laboratory settings and 4.4 °C in outdoor environments. These reductions were accompanied by an efficiency improvement of approximately 5% and 4%, respectively. This enhanced efficiency translates into substantial annual energy savings, estimated at 1.9 terawatt-hours when considering the use of LED streetlights in the United States. Furthermore, this electricity saving corresponds to a reduction of approximately 1.3 million metric tons of CO2 emissions, equivalent to 0.03% of the total annual CO2 emissions by the United States in 2018.

Mucosal immunology of the ocular surface

The eye is a sensory organ exposed to the environment and protected by a mucosal tissue barrier. While it shares a number of features with other mucosal tissues, the ocular mucosal system, composed of the conjunctiva, Meibomian glands, and lacrimal glands, is specialized to address the unique needs of (a) lubrication and (b) host defense of the ocular surface. Not surprisingly, most challenges, physical and immunological, to the homeostasis of the eye fall into those two categories. Dry eye, a dysfunction of the lacrimal glands and/or Meibomian glands, which can both cause, or arise from, sensory defects, including those caused by corneal herpes virus infection, serve as examples of these perturbations and will be discussed ahead. To preserve vision, dense neuronal and immune networks sense various stimuli and orchestrate responses, which must be tightly controlled to provide protection, while simultaneously minimizing collateral damage. All this happens against the backdrop of, and can be modified by, the microorganisms that colonize the ocular mucosa long term, or that are simply transient passengers introduced from the environment. This review will attempt to synthesize the existing knowledge and develop trends in the study of the unique mucosal and immune elements of the ocular surface.

Skill dependencies uncover nested human capital

Modern economies require increasingly diverse and specialized skills, many of which depend on the acquisition of other skills first. Here we analyse US survey data to reveal a nested structure within skill portfolios, where the direction of dependency is inferred from asymmetrical conditional probabilities—occupations require one skill conditional on another. This directional nature suggests that advanced, specific skills and knowledge are often built upon broader, fundamental ones. We examine 70 million job transitions to show that human capital development and career progression follow this structured pathway in which skills more aligned with the nested structure command higher wage premiums, require longer education and are less likely to be automated. These disparities are evident across genders and racial/ethnic groups, explaining long-term wage penalties. Finally, we find that this nested structure has become even more pronounced over the past two decades, indicating increased barriers to upward job mobility.

Modeling of magnetic vestibular stimulation experienced during high-field clinical MRI

High-field magnetic resonance imaging (MRI) is a powerful diagnostic tool but can induce unintended physiological effects, such as nystagmus and dizziness, potentially compromising the comfort and safety of individuals undergoing imaging. These effects likely result from the Lorentz force, which arises from the interaction between the MRI’s static magnetic field and electrical currents in the inner ear. Yet, the Lorentz force hypothesis fails to explain observed eye movement patterns in healthy adults fully. This study explores these effects and tests whether the Lorentz force hypothesis adequately explains magnetic vestibular stimulation.

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