690 research outputs found
Twitter and School Leaders: Examining Practices in a Twitter Chat
Background: Despite its potential, little is known about how school leaders use social media or the benefits of doing so. This includes the social media platform, Twitter, and the grass-roots phenomenon of using Twitter chats to connect, communicate, and learn from others. Purpose: The purpose of this qualitative study was to explore whether school leaders who engage in Twitter chats show key characteristics of a community of practice. Literature Review: The purpose of the literature review was to provide background knowledge on communities of practice, social media, and their combined potential for providing school leaders with viable ways to improve their leadership practices. Research Design: A qualitative research design, based on a research approach of qualitative content analysis, directed this study. The theoretical framework was based upon two theories of social learning: communities of practice and connectivism. Data Collection and Analysis: Based on the data collected from an analysis of school leaders’ tweets during an educational Twitter chat, a content analysis revealed two key themes with implications for school leaders. Results: Following the analysis of 1, 741 leader tweets, two primary themes were uncovered in this research, both of which provided an answer to the central research question of the study. First, the structure and content of #satchat shows the presence of the main elements of a community of practice. Second, activities indicative of a community of practice, such as problem solving, seeking experience and mapping knowledge were also evident. Conclusion: Twitter provides an opportunity for school leaders to join a community of practice that enables them to learn from each other and exchange ideas that support their professional growth. As participants share their expertise, they are able to drive strategy, solve problems, and transfer best practices. These findings might be of particular interest to busy school leaders with limited time and resources to invest in their own professional learning
The 3.1 micrometer ice band in infrared reflection nebulae
Recent observations show that infrared reflection nebulae are common phenomena in star forming regions. Extensive observations were made of two nearby infrared reflection nebulae, Orin Molecular Cloud 2 IRS1 (OMC-2/IRS1) and Cepheus A IRS6a (Cep-A/IRS6a). Mie scattering models of ice coated grains were used to study the constraints on the properties and locations of grains that could produce a feature similar to that observed in OMC-2 and Cep-A. It was concluded that scattering by ice particles alone could not be responsible for the 3.1 micron feature observed in infrared reflection nebulae
Infrared reflection nebulae in Orion molecular cloud 2
New obervations of Orion Molecular Cloud-2 have been made from 1-100 microns using the NASA Infrared Telescope Facility and the Kuiper Airborne Observatory. An extensive program of polarimetry, photometry and spectrophotometry has shown that the extended emission regions associated with two of the previously known near infrared sources, IRS1 and IRS4, are infrared reflection nebulae, and that the compact sources IRS1 and IRS4 are the main luminosity sources in the cloud. The constraints from the far infrared observations and an analysis of the scattered light from the IRS1 nebula show that OMC-2/IRS1 can be characterized by L less than or equal to 500 Solar luminosities and T approx. 1000 K. The near infrared (1-5) micron albedo of the grains in the IRS1 nebula is greater than 0.08
Organics and Ices in the Outer Solar System: Connections to the Interstellar Medium
The solar nebula, that aggregate of gas and dust that formed the birthplace of the Sun, planets and plethora of small bodies comprising the Solar System, originated in a molecular cloud that is thought to have spawned numerous additional stars, some with their own planets and attendant small bodies. The question of the chemical and physical reprocessing of the original interstellar materials in the solar nebula has challenged both theory and observations. The acquisition and analysis of samples of comet and asteroid solids, and a growing suite of in-situ and close-up analyses of relatively unaltered small Solar System bodies now adds critical new dimensions to the study of the origin and evolution of the early solar nebula. Better understanding the original composition of the material from which our solar nebula formed, and the processing that material experienced, will aid in formulations of chemistry that might occur in other solar systems. While we seek to understand the compositional history of planetary bodies in our own Solar System, we will inevitably learn more about the materials that comprise exoplanets and their surrounding systems
Interstellar Organics, the Solar Nebula, and Saturn's Satellite Phoebe
The diffuse interstellar medium inventory of organic material (Pendleton et al. 1994, Pendleton & Allamandola 2002) was likely incorporated into the molecular cloud in which the solar nebula condensed. This provided the feedstock for the formation of the Sun, major planets, and the smaller icy bodies in the region outside Neptune's orbit (transneptunian objects, or TNOs). Saturn's satellites Phoebe, Iapetus, and Hyperion open a window to the composition of one class of TNO as revealed by the near-infrared mapping spectrometer (VIMS) on the Cassini spacecraft at Saturn. Phoebe (mean diameter 213 km) is a former TNO now orbiting Saurn. VIMS spaectral maps of PHoebe's surface reveal a complex organic spectral signature consisting of prominent aromatic (CH) and alophatic hydrocarbon (CH2, CH3) absorption bands (3.2-3.6 micrometers). Phoebe is the source of a huge debris ring encircling Saturn, and from which particles (approximately 5-20 micrometer size) spiral inward toward Saturn. They encounter Iapetus and Hperion where they mix with and blanket the native H2O ice of those two bodies. Quantitative analysis of the hydrocarbon bands on Iapetus demonstrates that aromatic CH is approximately 10 times as abundant as aliphatic CH2+CH3, significantly exceeding the strength of the aromatic signature in interplanetary dust particles, comet particles, ad in carbonaceous meteorites (Cruikshank et al. 2013). A similar excess of aromatics over aliphatics is seen in the qualitative analysis of Hyperion and Phoebe itself (Dalle Ore et al. 2012). The Iapetus aliphatic hydrocarbons show CH2/CH3 approximately 4, which is larger than the value found in the diffuse ISM (approximately 2-2.5). In so far as Phoebe is a primitive body that formed in the outer regions of the solar nebula and has preserved some of the original nebula inventory, it can be key to understanding the content and degree of procesing of the nebular material. There are other Phoebe-like TNOs that are presently beyond our ability to study in the organic spectral region, but JWST will open that possibility for a number of objects. We now need to explore and understand the connection of this organic-bearing Solar System material to the solar nebula the the inventory of ISM materials incorporated therein
From Stardust to Planetesimals: Contributed Papers
On June 24 through 26, 1996, a scientific conference entitled From Stardust to Planetesimals was held at the Westin Hotel, Santa Clara, California, as part of the 108th annual meeting of the Astronomical Society of the Pacific. Over the last decade, our understanding of the formation and early evolution of the solar system has advanced considerably due to progress that has been made simultaneously on many fronts. Stardust has been isolated in meteorites and interplanetary dust particles (IDP's), providing us with sample materials which predate the solar system and which offer clues to the processing that has occurred. At the same time, infrared studies have led to a better characterization of the composition of interstellar dust, which is now readily accepted as an important component of the interstellar medium infrared observations have also provided a much better view of the star-formation process and the role of dust therein. Recently, the presence of Kuiper Belt planetesimals has been confirmed and spectroscopy of these rather pristine objects may soon become available. Analysis of spacecraft data from the Comet Halley flybys has yielded a wealth of information on the composition of this comet. These observational advances have changed our understanding of planetesimal processing. The launch of the Infrared Space Observatory, the opening of 10-meter class telescopes, and, in the longer term, the Rosetta mission, promise to continue to broaden and deepen our understanding of the evolution from stardust to planetesimals. For these reasons we considered it timely to organize a meeting focused on the processes that connect stardust and planetesimals. The goal of this meeting was, therefore, to bring together astronomers interested in star- and planet-formation, planetary scientists studying early solar system relics, laboratory scientists studying the processing of analogs, and scientists analyzing meteorites and interplanetary dust particles, grain by grain. As a result of this endeavor, over 200 participants, including 153 scientists from 14 different countries, gathered to discuss the origin and evolution of stardust. We hope that this encounter in Santa Clara will foster an ongoing interchange of information and ideas within this diverse group of scientists. A major aim of this meeting was to produce conference proceedings which reflect the current situation regarding the evolution from stardust to planetesimals
NASA's Solar System Exploration Research Virtual Institute: Merging Science and Exploration
NASA's Solar System Exploration Research Virtual Institute (SSERVI) represents a close collaboration between science, technology and exploration, and was created to enable a deeper understanding of the Moon and other airless bodies. SSERVI is supported jointly by NASA's Science Mission Directorate and Human Exploration and Operations Mission Directorate. The institute currently focuses on the scientific aspects of exploration as they pertain to the Moon, Near Earth Asteroids (NEAs) and the moons of Mars, but the institute goals may expand, depending on NASA's needs, in the future. The 9 initial teams, selected in late 2013 and funded from 2014-2019, have expertise across the broad spectrum of lunar, NEA, and Martian moon sciences. Their research includes various aspects of the surface, interior, exosphere, near-space environments, and dynamics of these bodies. NASA anticipates a small number of additional teams to be selected within the next two years, with a Cooperative Agreement Notice (CAN) likely to be released in 2016. Calls for proposals are issued every 2-3 years to allow overlap between generations of institute teams, but the intent for each team is to provide a stable base of funding for a five year period. SSERVI's mission includes acting as a bridge between several groups, joining together researchers from: 1) scientific and exploration communities, 2) multiple disciplines across a wide range of planetary sciences, and 3) domestic and international communities and partnerships. The SSERVI central office is located at NASA Ames Research Center in Mountain View, CA. The administrative staff at the central office forms the organizational hub for the domestic and international teams and enables the virtual collaborative environment. Interactions with geographically dispersed teams across the U.S., and global partners, occur easily and frequently in a collaborative virtual environment. This poster will provide an overview of the 9 current US teams and international partners, as well as information about outreach efforts and future opportunities to participate in SSERVI
Investigating Gravity Wave Characteristics and Mesospheric Temperature Variability over Antarctica
第2回極域科学シンポジウム/第35回極域宙空圏シンポジウム 11月14日(月) 国立極地研究所 2階大会議
The interstellar medium toward the Galactic center source 2MASS J17470898-2829561
Interstellar matter and star formatio
- …