Quantum field theory and classical optics: determining the fine structure constant

The properties of the vacuum are described by quantum physics including the response to external fields such as electromagnetic radiation. Of the two parameters that govern the details of the electromagnetic field dynamics in vacuum, one is fixed by the requirement of Lorentz invariance $c= 1/\sqrt{\varepsilon_{0} \mu_{0}}$. The other one, $Z_{0}= \sqrt{\mu_{0}/\varepsilon_{0}} = 1/(c\varepsilon_{0})$ and its relation to the quantum vacuum, is discussed in this contribution. Deriving $\varepsilon_{0}$ from the properties of the quantum vacuum implies the derivation of the fine structure constant.Comment: 3 pages. Invited contribution to MPLP 2017 Novosibirsk "Modern Problems in Laser Physics". Comments welcome

Tropical Dry Forest Succession and the Contribution of Lianas to Wood Area Index (WAI)

The transmission and interception of light through the canopy is an important indicator of forest productivity in tropical forest ecosystems, and the amount of light that eventually reaches the forest floor is influenced by its interactions with leaves, branches, fruits, and flowers among many different canopy elements. While most studies of forest canopy light interception focus on leaf area index (LAI), very few studies have examined wood area index (WAI), which may account for a substantial component of light interception in tropical forests. The influence of lianas on the interception of light and their overall contribution to WAI is a potentially important factor, but it is generally overlooked because of its difficulty to assess. In this paper we evaluate the relative contribution that lianas have to the overall WAI and canopy openness as function of successional stage via a latitudinal comparison of sites across the Americas (Mexico, Costa Rica and Brazil). Our results suggest that lianas significantly increase WAI and decreases canopy openness. However, lianas were absent at all of our study sites where canopy openness exceeded 60%. Our data are the first to explicitly document the role of lianas in the estimation of WAI and, overall, they will contribute to better estimations of ecosystem level LAI in tropical environments, where there is a lack of data on WAI

93 years of stand density and land-use legacy research at the Coulter Ranch Study Site

In 1913, the Fort Valley Experimental Forest initiated an unprecedented case-study experiment to determine the effects of harvesting methods on tree regeneration and growth on a ponderosa pine-Gambel oak forest at Coulter Ranch in northern Arizona. The harvesting methods examined were seed-tree, group selection, and light selection. In addition, the effects of livestock grazing (excluded or not) were examined. We revisited the Coulter Ranch Study Site to examine the effects of these treatments on historical (1913) and contemporary (2003-2006) stand density and tree size. The key finding was that while initial 1913 harvests reduced average pine density by one- to two-thirds, tree densities increased from three to nine times those prior to harvest over the 93-year period. The greatest increase was in the seed-tree method

Percepciones de docentes acerca de las experiencias de desarrollo profesional: una preocupación que continúa

Teachers’ perceptions of professional development experiences related to process, content, and context were explored to better address leadership preparation needs. Teachers responded to the Professional Development Questionnaire, three demographic variables (teaching experience, Title 1 status, and current grade level) pertaining to the individual, and one open-ended comment field. A total of 327 teachers from a large western school district in the United States responded. The findings indicated that there were no significant differences for the three demographic grouping variables. Overall, results revealed low mean values, indicating that teachers disagreed or strongly disagreed with statements related to their professional development experiences. Teachers also indicated that their own building administrators did not value professional development. Finally, teachers’ perceptions of professional development also suggested that professional development topics were irrelevant, and that they were not provided with enough time to integrate topics into their current practice.Se exploraron las percepciones de maestros acerca de las experiencias de desarrollo profesional relacionadas con el proceso, el contenido y el contexto, a fin de responder mejor a las necesidades de preparación para el liderazgo. Maestros respondieron al Cuestionario de Desarrollo Profesional, tres variables de agrupaciones demográficas (experiencia enseñando, estado de Título 1, y nivel de grado actual) pertenecientes al individuo, y un campo de comentarios de composición abierta. Un total de 327 maestros de un distrito escolar grande del occidente de los Estados Unidos respondió. Los resultados revelaron que no había diferencias significativas para las tres variables de agrupación demográfica. En general, los resultados revelaron bajos valores promedios, indicando que los maestros estaban en desacuerdo, o fuertemente en desacuerdo con las declaraciones relacionadas a sus experiencias de desarrollo profesional. Los maestros también indicaron que sus propios administradores no valoraban el desarrollo profesional. Finalmente, las percepciones de los maestros de desarrollo profesional también sugirieron que los temas al respecto eran irrelevantes y que ellos no tenían suficiente tiempo para integrar dichas cuestiones en su práctica cotidiana

Panel II

Cells, Catacombes, and Coffins: Charting the Destiny of Race Relations in Intruder in the Dust / Margaret Rayburn Kramar, University of Kansas Critical Intruders: Negotiating Race, Crime, and the Law in Intruder in the Dust / Esther Sanchez-Pardo, Universidad Compultense de Madrid To Survive What Looked Out : Bodily Encounters and the Forensic Trail in The Bear and Intruder in the Dust / Rachel Kathleen Watson, University of Chicag

Molecular Nevogenesis

Despite recent advances, the biology underlying nevogenesis remains unclear. Activating mutations in NRAS, HRAS, BRAF, and GNAQ have been identified in benign nevi. Their presence roughly correlates with congenital, Spitz, acquired, and blue nevi, respectively. These mutations are likely to play a critical role in driving nevogenesis. While each mutation is able to activate the MAP kinase pathway, they also interact with a host of different proteins in other pathways. The different melanocytic developmental pathways activated by each mutation cause the cells to migrate, proliferate, and differentiate to different extents within the skin. This causes each mutation to give rise to a characteristic growth pattern. The exact location and differentiation state of the cell of origin for benign moles remains to be discovered. Further research is necessary to fully understand nevus development given that most of the same developmental pathways are also present in melanoma

Nevogenesis: A Benign Metastatic Process?

It is generally accepted that cutaneous nevogenesis is a localized event that occurs exclusively in the dermis and/or epidermis. However, the discovery of nevocytes circulating in the peripheral blood suggests that other, more systemic, benign metastatic processes could also be involved. The theoretical role of lymphatic and hematogenous dissemination of loosely adherent, immature nevus progenitor cells in the development of nodal nevi and eruptive melanocytic nevi will be reviewed

Disrupting the Status Quo: Forging a Path to Promotion that Explicitly Recognizes and Values Faculty Work Focused on Diversity, Equity, and Inclusion

This article focuses on the importance of creating new pathways to promotion and tenure that explicitly recognize and reward excellence related to diversity, equity, and inclusion (DEI). We explain the approach we have taken at Indiana University–Purdue University Indianapolis (IUPUI). Challenges to the status quo related to faculty systems of evaluation are reviewed, as well as the urgency afforded by the interconnectedness of a global pandemic, an economic recession, and a national reckoning with respect to race that could accelerate reforms in higher education. We reflect upon eight critical lessons learned when implementing a new pathway to promotion that recognizes integrated excellence in DEI activities. We hope the lessons we learned will inspire other institutions to lead similar transformational change efforts aimed at disrupting systems that historically have created inequities in the retention and advancement of faculty from marginalized groups