1,847 research outputs found

    Reframing the Opioid Epidemic as a National Emergency

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    On August 10, 2017 President Trump announced his intention to declare a national emergency following the recommendation of the White House Commission on Combating Drug Addiction and the Opioid Crisis. Opioid abuse is among the most consequential preventable public health threats facing the nation. More than 600,000 deaths have occurred to date, with 180,000 more predicted by 2020. Of the 20.5 million US residents 12 years or older with substance use disorders in 2015, 2 million were addicted to prescription pain relievers. A national emergency declaration authorizes public health powers, mobilizes resources, and facilitates innovative strategies to curb a rapidly escalating public health crisis

    Dicke Superradiance in Solids

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    Recent advances in optical studies of condensed matter have led to the emergence of phenomena that have conventionally been studied in the realm of quantum optics. These studies have not only deepened our understanding of light-matter interactions but also introduced aspects of many-body correlations inherent in optical processes in condensed matter systems. This article is concerned with superradiance (SR), a profound quantum optical process predicted by Dicke in 1954. The basic concept of SR applies to a general NN-body system where constituent oscillating dipoles couple together through interaction with a common light field and accelerate the radiative decay of the system. In the most fascinating manifestation of SR, known as superfluorescence (SF), an incoherently prepared system of NN inverted atoms spontaneously develops macroscopic coherence from vacuum fluctuations and produces a delayed pulse of coherent light whose peak intensity N2\propto N^2. Such SF pulses have been observed in atomic and molecular gases, and their intriguing quantum nature has been unambiguously demonstrated. Here, we focus on the rapidly developing field of research on SR in solids, where not only photon-mediated coupling but also strong Coulomb interactions and ultrafast scattering exist. We describe SR and SF in molecular centers in solids, molecular aggregates and crystals, quantum dots, and quantum wells. In particular, we will summarize a series of studies we have recently performed on quantum wells in strong magnetic fields. These studies show that cooperative effects in solid-state systems are not merely small corrections that require exotic conditions to be observed; rather, they can dominate the nonequilibrium dynamics and light emission processes of the entire system of interacting electrons.Comment: 23 pages, 26 figure

    A table-top, repetitive pulsed magnet for nonlinear and ultrafast spectroscopy in high magnetic fields up to 30 T

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    We have developed a mini-coil pulsed magnet system with direct optical access, ideally suited for nonlinear and ultrafast spectroscopy studies of materials in high magnetic fields up to 30 T. The apparatus consists of a small coil in a liquid nitrogen cryostat coupled with a helium flow cryostat to provide sample temperatures down to below 10 K. Direct optical access to the sample is achieved with the use of easily interchangeable windows separated by a short distance of ~135 mm on either side of the coupled cryostats with numerical apertures of 0.20 and 0.03 for measurements employing the Faraday geometry. As a demonstration, we performed time-resolved and time-integrated photoluminescence measurements as well as transmission measurements on InGaAs quantum wells.Comment: 7 pages, 6 figure

    Effects of shear on eggs and larvae of striped bass, morone saxatilis, and white perch, M. americana

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    Shear stress, generated by water movement, can kill fish eggs and larvae by causing rotation or deformation. Through the use of an experimental apparatus, a series of shear (as dynes/cm2)-mortality equations for fixed time exposures were generated for striped bass and white perch eggs and larvae. Exposure of striped bass eggs to a shear level of 350 dynes/cm2 kills 36% of the eggs in 1 min; 69% in 2 min, and 88% in 4 min; exposure of larvae to 350 dynes/cm2 kills 9.3% in 1 min, 30.0% in 2 min, and 68.1% in 4 min. A shear level of 350 dynes/cm2 kills 38% of the white perch eggs in 1 min, 41% in 2 min, 89% in 5 min, 96% in 10 min, and 98% in 20 min. A shear level of 350 dynes/cm2 applied to white perch larvae destroys 38% of the larvae in 1 min, 52% in 2 min, and 75% in 4 min. Results are experimentally used in conjunction with the determination of shear levels in the Chesapeake and Delaware Canal and ship movement for the estimation of fish egg and larval mortalities in the field

    Fermi-Edge Superfluorescence from a Quantum-Degenerate Electron-Hole Gas

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    We report on the observation of spontaneous bursts of coherent radiation from a quantum-degenerate gas of nonequilibrium electron-hole pairs in semiconductor quantum wells. Unlike typical spontaneous emission from semiconductors, which occurs at the band edge, the observed emission occurs at the quasi-Fermi edge of the carrier distribution. As the carriers are consumed by recombination, the quasi-Fermi energy goes down toward the band edge, and we observe a continuously red-shifting streak. We interpret this emission as cooperative spontaneous recombination of electron-hole pairs, or superfluorescence, which is enhanced by Coulomb interactions near the Fermi edge. This novel many-body enhancement allows the magnitude of the spontaneously developed macroscopic polarization to exceed the maximum value for ordinary superfluorescence, making electron-hole superfluorescence even more "super" than atomic superfluorescence.Comment: 10 pages, 5 figure

    Diverse Cultures and Shared Experiences Shape Asian American Identities

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    Pew Research Center conducted this analysis to understand the rich diversity of people of Asian origin or ancestry living in the United States and their views of identity. The study is part of the Center's multiyear, comprehensive, in-depth quantitative and qualitative research effort focused on the nation's Asian population. Its centerpiece is this nationally representative survey of 7,006 Asian adults exploring the experiences, attitudes and views of Asians living in the U.S. The survey sampled U.S. adults who self-identify as Asian, either alone or in combination with other races or Hispanic ethnicity. It was offered in six languages: Chinese (Simplified and Traditional), English, Hindi, Korean, Tagalog and Vietnamese. Responses were collected from July 5, 2022, to Jan. 27, 2023, by Westat on behalf of Pew Research Center

    In Their Own Words: Asian Immigrants Experiences Navigating Language Barriers in the United States

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    New immigrant arrivals to the United States face many challenges and obstacles when navigating their daily lives. For Asian immigrants, these include language and cultural obstacles that impact those who arrive with little to no proficiency in English. But navigating life in America also impacts English-speaking immigrants as they adjust to life in a new country with its own unique linguistic and cultural quirks.In 2021, Pew Research Center conducted 49 focus groups with Asian immigrants to understand the challenges they faced, if any, after arriving in the country. The focus groups consisted of 18 distinct Asian origins and were conducted in 17 Asian languages.This report explores three broad themes from the focus group discussions: the challenges Asian immigrants have faced in navigating daily life and communicating in English; tools and strategies they used to learn the language; and types of help they received from others in adapting to English-speaking settings. The experiences discussed may not resonate with all Asian U.S. immigrants, but the study sought to capture a wide range of views by including participants of different languages, immigration or refugee experiences, educational backgrounds and income levels
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