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
Kennedy P.,Lewis And Clark College
New Phytologist | Year: 2010
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
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.
Agency: NSF | Branch: Standard Grant | Program: | Phase: FED CYBER SERV: SCHLAR FOR SER | Award Amount: 166.53K | Year: 2015
The EDURange project, a collaboration between Evergreen State College and Lewis and Clark College, will support faculty teaching cyber security by providing hands-on exercises, a student-staffed help-desk, and webinars. These resources will be designed to be easy to deploy and will be interactive, competitive and collaborative to ensure student engagement. The availability of these resources will make it easier for computer science faculty with little prior background to teach security across, and will increase the number of schools teaching cyber security concepts. As a result this project will produce more students with the analytical skills required to secure computing assets in the Pacific Northwest and in turn will help to ensure American technical competitiveness in the future.
The resources will be linked to the concepts and learning outcomes defined in the IEEE/ACM CS Curricula 2013 report. Support for these resources will be provided by a student-run help desk and a user interface that will allow faculty to modify exercises to fit the content and level of difficulty of their classes. Background material will be provided for students to make the exercises applicable to a variety of computer science classes. These resources will fulfill four important needs: (1) expanding and disseminating technology ? improving exercises using EDURange, a flexible, cloud-based teaching infrastructure, (2) faculty development ? helping them use hands-on security exercises in their classrooms and providing curricular resources, (3) student engagement ? developing their skills, leveraging their talent and knowledge, and mentoring them to become the next generation of teachers and researchers, and (4) education research --investigating the acquisition of analytical skills.
Assessment of the resources will focus on four activities: (1) a quantitative evaluation and summary of how often and how widely the resources are used, (2) a qualitative assessment of how well exercises map or express the cyber security knowledge units of CS2013, (3) an assessment of faculty experience using the resources in their courses, and (4) an evaluation of the experience using the resources by security faculty, professionals, and students.