Entity

Time filter

Source Type

Portland, OR, United States

Lewis & Clark College is a private liberal arts college located in Portland, Oregon. It has an undergraduate College of Arts and science, a School of Law, and a Graduate School of Education and Counseling Wikipedia.


Wang H.,University of Oregon | O'Leary S.,Lewis And Clark College
Journal of the Optical Society of America B: Optical Physics | Year: 2012

In this paper, we review our recent experimental studies on electromagnetically induced transparency (EIT) from electron spin coherences in semiconductor quantum wells. Coherent Raman resonances, manifestations of EIT from electron spin coherences at relatively low pump intensities, were demonstrated in both V-type and Ë-type three-level systems via heavy-hole exciton and trion transitions in undoped and doped quantum wells, respectively. Coherent Raman resonances from electron spin coherences via light-hole transitions were also demonstrated in a waveguide geometry that enables a long optical interaction length as well as a large absorption coefficient. Experimental approaches that can avoid or reduce detrimental many-body effects in quantum wells are suggested for the realization of nearly ideal EIT processes. © 2012 Optical Society of America. Source


Bostian M.B.,Lewis And Clark College | Herlihy A.T.,Oregon State University
Ecological Economics | Year: 2014

This study uses the directional output distance function, a multi-output economic production frontier model, to value the physical tradeoffs between agricultural production and wetland condition in the U.S. Mid-Atlantic region Nanticoke River watershed. We combine detailed ecological indicator data to measure wetland condition with satellite imagery land use data on agricultural production in the watershed. Our estimation procedure adapts the bootstrap methods originally developed by Simar and Wilson (1998) for nonparametric efficiency estimates to the quadratic directional output distance function. We find substantial variation in tradeoff values across the watershed, which could be used to target wetland conservation efforts in the region. © 2014 Elsevier B.V. Source


The field of ectomycorrhizal fungal (EMF) ecology has largely developed outside the ecological mainstream, owing in large part to the challenges in studying the structure and dynamics of EMF communities. With advances in molecular identification and other research techniques, however, there has been growing interest among mycologists and ecologists in understanding how different ecological factors affect EMF community structure and diversity. While factors such as soil chemistry and host specificity have long been considered important, an increasing number of laboratory and field studies have documented that interspecific competition also has a major impact on EMF species interactions and may significantly influence EMF community structure. In this review, I examine the progress that has been made in understanding the nature of EMF competition. Currently, there are four conclusions that can be drawn: negative competitive effects are rarely reciprocal; competitive outcomes are environmentally context-dependent; field distributions often reflect competitive interactions; and timing of colonization influences competitive success. In addition, I highlight recent studies documenting links between competitive coexistence and EMF community structure, including checkerboard distributions, lottery models, storage effects, and colonization-competition tradeoffs. Finally, I discuss several aspects of EMF competition needing further investigation and some newer methods with which to address them. © The Author (2010). Journal compilation © New Phytologist Trust (2010). Source


Proctor J.D.,Lewis And Clark College
Journal of Environmental Studies and Sciences | Year: 2013

This essay reviews six books broadly addressing the Anthropocene-the recent epoch in which humans play a dominant role on the face of the earth. Concepts of nature are still significant in contemporary American environmentalism despite its increasing diversity of issues, and no matter what the Anthropocene's challenges to naturalness nor what level of comfort or discomfort these works display regarding the Anthropocene, they largely retain some notion of nature. For balance, three books are included that generally speak positively of the Anthropocene and three that express various concerns: the former include Love Your Monsters: Postenvironmentalism and the Anthropocene (2011), Rambunctious Garden: Saving Nature in a Post-Wild World (2011), and Living Through the End of Nature (2010); and the latter include Eaarth: Making a Life on a Tough New Planet (2010), The Nature Principle: Human Restoration and the End of Nature-Deficit Disorder (2011), and Authenticity in Nature: Making Choices About the Naturalness of Ecosystems (2011). The latter group continues to distinguish nature from culture in the Anthropocene, thus effectively counting to two, whereas most among the former tend to count to one in celebrating a cultured nature. Embrace of the Anthropocene could, however, lead to counting beyond two by letting go of nature (and culture) as metaphysical categories qua moral shortcuts. The science and politics of living well in this enduring age of the Anthropocene may require attention less to generalities of nature than the interwoven details that constitute our environment. © 2013 AESS. Source


Grant
Agency: NSF | Branch: Standard Grant | Program: | Phase: AMO Experiment/Atomic, Molecul | Award Amount: 195.01K | Year: 2015

Significant advancements in 21st century physics have relied on the discovery that properties of atoms are not fixed, but can be changed by interactions with laser light. The ability to understand and control these sensitive interactions is also the key to the creation of new atom-light based technologies. Some atom-light interactions are sensitive to the surrounding magnetic field. As an example, an atom is extremely selective about the precise colors of light it absorbs, but when it is placed in a magnetic field, the atoms color choices will shift depending on the strength of the field. Such interactions can be used as the foundation of a device, called an atomic magnetometer, that can measure unknown magnetic fields. This investigation studies interactions between laser light and a specially prepared gas of atoms that is sensitive to small variations in the surrounding magnetic field. The special preparation uses two lasers and a controlled magnetic field to temporarily but dramatically change how laser light travels through a gas of atoms. As a result, the laser lights brightness fluctuates, or flickers, in ways that are not yet fully understood. These fluctuations not only carry information about the atoms, but they are also especially sensitive to magnetic field variations. This research will further our scientific understanding of atom-light interactions, which is of broad interest for many technological applications. Simultaneously, the research will produce new techniques for detecting small, unknown magnetic fields, like the magnetic fields emitted from the human heart. The new detection methods will potentially impact a broad range of medical and scientific fields, and because they make use of low-cost and potentially portable laser systems, any resulting technological applications will be widely accessible and suitable for use outside of the laboratory environment. Undergraduate students will be involved at all stages of this research agenda, preparing them for careers in research science and other STEM-related fields.

Light intensity fluctuations derived from atomic coherence can encode valuable information about coherence dynamics in an atomic vapor. Furthermore, they provide a platform for a new class of compact and simple atomic magnetometers. This research agenda uses low-cost, free-running diode lasers with inherent frequency noise that is converted into information-rich intensity noise near an atomic resonance. The amplitude and phase of the intensity fluctuations are particularly sensitive to small magnetic field variations near an atomic coherence between Zeeman sublevels. Hanle effect Electromagnetically Induced Transparency will be induced in rubidium vapor and used to prototype and optimize a novel magnetometry technique relying on coherence-derived light fluctuations. The converted laser intensity noise will be studied using self-correlations and spectrum analysis. The findings will deepen our understanding of the relationship between the light fluctuations and the underlying atomic coherence, as well as give us the tools to build a new atomic magnetometer. Moreover, the results will provide useful insight for mitigating noise from imperfect lasers.

Discover hidden collaborations