1,847 research outputs found
Reframing the Opioid Epidemic as a National Emergency
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
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 -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 inverted atoms spontaneously develops
macroscopic coherence from vacuum fluctuations and produces a delayed pulse of
coherent light whose peak intensity . 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
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
Legislation and Administration: Stumbling Giants -- A Path to Progress through Metropolitan Annexation
Legislation and Administration: Stumbling Giants -- A Path to Progress through Metropolitan Annexation
Effects of shear on eggs and larvae of striped bass, morone saxatilis, and white perch, M. americana
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
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
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
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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