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Articles 1 - 14 of 14
Full-Text Articles in Entire DC Network
Self-Assembled In0.5Ga0.5As Quantum Dots On Gap, Yuncheng Song, Paul J. Simmonds, Minjoo Larry Lee
Self-Assembled In0.5Ga0.5As Quantum Dots On Gap, Yuncheng Song, Paul J. Simmonds, Minjoo Larry Lee
Paul J. Simmonds
We demonstrate the growth and luminescence of coherently strained In0.5Ga0.5As self-assembled quantum dots on GaP. Cross-sectional and planar-view transmission electron microscopy confirmed the dislocation-free nature of the In0.5Ga0.5As quantum dots and GaP cap layers. Intense photoluminescence from the quantum dots was measured at 80 K and was visible to the unaided eye in ambient lighting. The photoluminescence results show that emission energy can be controlled by varying the In0.5Ga0.5As deposition thickness. In combination with recent advances in the growth of GaP on Si, the In0.5Ga0.5 …
Too Little, Too Late: How The Tidal Evolution Of Hot Jupiters Affects Transit Surveys Of Clusters, John H. Debes, Brian Jackson
Too Little, Too Late: How The Tidal Evolution Of Hot Jupiters Affects Transit Surveys Of Clusters, John H. Debes, Brian Jackson
Brian Jackson
The tidal evolution of hot Jupiters may change the efficiency of transit surveys of stellar clusters. The orbital decay that hot Jupiters suffer may result in their destruction, leaving fewer transiting planets in older clusters. We calculate the impact tidal evolution has for different assumed stellar populations, including that of 47 Tuc, a globular cluster that was the focus of an intense Hubble Space Telescope search for transits. We find that in older clusters, one expects to detect fewer transiting planets by a factor of 2 for surveys sensitive to Jupiter-like planets in orbits out to 0.5 AU, and up …
Tensile Strained Island Growth At Step-Edges On Gaas(110), Paul J. Simmonds, M. L. Lee
Tensile Strained Island Growth At Step-Edges On Gaas(110), Paul J. Simmonds, M. L. Lee
Paul J. Simmonds
We report the growth of tensile strained GaP islands on a GaAs(110) surface. Three-dimensional island formation proceeds via a step-edge nucleation process. To explain the dislocation-free nature of these islands, we consider the kinetics of strain relief within the context of a model for dislocation glide as a function of surface orientation and sign of strain.
The Roles Of Tidal Evolution And Evaporative Mass Loss In The Origin Of Corot-7 B, Brian Jackson, Neil Miller, Rory Barnes, Sean N. Raymond, Jonathan J. Fortney, Richard Greenberg
The Roles Of Tidal Evolution And Evaporative Mass Loss In The Origin Of Corot-7 B, Brian Jackson, Neil Miller, Rory Barnes, Sean N. Raymond, Jonathan J. Fortney, Richard Greenberg
Brian Jackson
CoRoT-7 b is the first confirmed rocky exoplanet, but, with an orbital semimajor axis of 0.0172 au, its origins may be unlike any rocky planet in our Solar system. In this study, we consider the roles of tidal evolution and evaporative mass loss in CoRoT-7 b's history, which together have modified the planet's mass and orbit. If CoRoT-7 b has always been a rocky body, evaporation may have driven off almost half its original mass, but the mass loss may depend sensitively on the extent of tidal decay of its orbit. As tides caused CoRoT-7 b's orbit to decay, they …
Recent Transits Of The Super-Earth Exoplanet Gj 1214b, Pedro V. Sada, Drake Deming, Brian Jackson, Donald E. Jennings, Steven W. Peterson, Flynn Haase, Kevin Bays, Eamon O'Gorman, Alan Lundsford
Recent Transits Of The Super-Earth Exoplanet Gj 1214b, Pedro V. Sada, Drake Deming, Brian Jackson, Donald E. Jennings, Steven W. Peterson, Flynn Haase, Kevin Bays, Eamon O'Gorman, Alan Lundsford
Brian Jackson
We report recent ground-based photometry of the transiting super-Earth exoplanet GJ 1214b at several wavelengths, including the infrared near 1.25 μm (J band). We observed a J-band transit with the FLAMINGOS infrared imager and the 2.1 m telescope on Kitt Peak, and we observed several optical transits using a 0.5 m telescope on Kitt Peak and the 0.36 m Universidad de Monterrey Observatory telescope. Our high-precision J-band observations exploit the brightness of the M dwarf host star at this infrared wavelength as compared with the optical and are significantly less affected by stellar activity and limb darkening. We fit the …
Physical Basis Of The Inducer-Dependent Cooperativity Of The Central Glycolytic Genes Repressor/Dna Complex, Denis Chaix, Matthew L. Ferguson, Cedric Atmanene, Alain Van Dorsselaer, Sarah Sanglier-Cianférani, Catherine A. Royer, Nathalie Declerck
Physical Basis Of The Inducer-Dependent Cooperativity Of The Central Glycolytic Genes Repressor/Dna Complex, Denis Chaix, Matthew L. Ferguson, Cedric Atmanene, Alain Van Dorsselaer, Sarah Sanglier-Cianférani, Catherine A. Royer, Nathalie Declerck
Matthew L. Ferguson
The Central glycolytic genes Repressor (CggR) from Bacillus subtilis belongs to the SorC family of transcription factors that control major carbohydrate metabolic pathways. Recent studies have shown that CggR binds as a tetramer to its tandem operator DNA sequences and that the inducer metabolite, fructose 1,6-bisphosphate (FBP), reduces the binding cooperativity of the CggR/DNA complex. Here, we have determined the effect of FBP on the size, shape and stoichiometry of CggR complexes with full-length and half-site operator sequence by small-angle X-ray scattering, size-exclusion chromatography, fluorescence cross-correlation spectroscopy and noncovalent mass spectrometry (MS). Our results show that CggR forms a compact …
Tensile Strained Iii-V Self-Assembled Nanostructures On A (110) Surface, Minjoo L. Lee, Paul J. Simmonds
Tensile Strained Iii-V Self-Assembled Nanostructures On A (110) Surface, Minjoo L. Lee, Paul J. Simmonds
Paul J. Simmonds
The vast majority of research on epitaxial quantum dots use compressive strain as the driving force for self-assembly on the (001) surface, with InAs/GaAs(001) and Ge/Si(001) being the best-known examples. In this talk, I will discuss our work on determining the feasibility of growing coherent, tensile-strained III-V nanostructures on a (110) surface. GaP on GaAs(110) was chosen as an initial test system. It is hoped that our efforts on self-assembled, tensile-strained dots on a (110) surface will lead the way to new devices exploiting the fundamental differences between the (110) and (001) surfaces. Furthermore it is anticipated that this work …
Making Space For The “Nuances Of Truth”: Communication And Uncertainty At An Environmental Journalists’ Workshop, Jen Schneider
Making Space For The “Nuances Of Truth”: Communication And Uncertainty At An Environmental Journalists’ Workshop, Jen Schneider
Jen Schneider
In 2008, the Society of Environmental Journalists listed nearly 50 science or science immersion workshops for environmental journalists. Yet relatively little is known about the content of these workshops and their impact on participants. This ethnographic study, conducted at a science immersion workshop for environmental journalists, aims to fill this void in our knowledge. Relying on participant observation and depth interviews, the study suggests that such workshops are useful for participating journalists: Reporters feel they leave the workshop better understanding the scientific method and scientific uncertainty. But the findings also reveal that “metacommunication”—communication about communication—is equally as important as science …
Idaho Bird Observatory: Research, Education, Conservation - 24/7, Elise Faike
Idaho Bird Observatory: Research, Education, Conservation - 24/7, Elise Faike
Jay D. Carlisle
The Idaho Bird Observatory’s Lucky Peak bird monitoring station atop the foothills overlooking Boise is unique. During fall migration, it’s the only place in western North America that hosts some form of songbird or raptor research all day and all night—for downright fun 24/7!
Reproducibility Of Soil Moisture Ensembles When Representing Soil Parameter Uncertainty Using A Latin Hypercube–Based Approach With Correlation Control, Alejandro N. Flores, Dara Entekhabi, Rafael L. Bras
Reproducibility Of Soil Moisture Ensembles When Representing Soil Parameter Uncertainty Using A Latin Hypercube–Based Approach With Correlation Control, Alejandro N. Flores, Dara Entekhabi, Rafael L. Bras
Alejandro N. Flores
Representation of model input uncertainty is critical in ensemble-based data assimilation. Monte Carlo sampling of model inputs produces uncertainty in the hydrologic state through the model dynamics. Small Monte Carlo ensemble sizes are desirable because of model complexity and dimensionality but potentially lead to sampling errors and correspondingly poor representation of probabilistic structure of the hydrologic state. We compare two techniques to sample soil hydraulic and thermal properties (SHTPs): (1) Latin Hypercube (LH) based sampling with correlation control and (2) random sampling from SHTP marginal distributions. A hydrology model is used to project SHTP uncertainty onto the soil moisture state …
Growth Of Metamorphic Ingap For Wide-Bandgap Photovoltaic Junction By Mbe, John Simon, Stephanie Tomasulo, Paul J. Simmonds, Manuel J. Romero, Minjoo Larry Lee
Growth Of Metamorphic Ingap For Wide-Bandgap Photovoltaic Junction By Mbe, John Simon, Stephanie Tomasulo, Paul J. Simmonds, Manuel J. Romero, Minjoo Larry Lee
Paul J. Simmonds
Metamorphic triple-junction solar cells can currently attain efficiencies as high as 41.1%. Using additional junctions could lead to efficiencies above 50%, but require the development of a wide bandgap (2.0-2.2eV) material to act as the top layer. In this work we demonstrate wide bandgap InyGa1-yP grown on GaAsxP1-x via solid source molecular beam epitaxy. Unoptimized tensile GaAsxP1-x buffers grown on GaAs exhibit asymmetric strain relaxation, along with formation of faceted trenches 100-300 nm deep in the [01-1] direction. Smaller grading step size and higher substrate temperatures minimizes the facet trench …
Corot-7b: Super-Earth Or Super-Io?, Rory Barnes, Sean N. Raymond, Richard Greenberg, Brian Jackson, Nathan A. Kaib
Corot-7b: Super-Earth Or Super-Io?, Rory Barnes, Sean N. Raymond, Richard Greenberg, Brian Jackson, Nathan A. Kaib
Brian Jackson
CoRoT-7b, a planet about 70% larger than the Earth orbiting a Sun-like star, is the first-discovered rocky exoplanet, and hence has been dubbed a "super-Earth." Some initial studies suggested that since the planet is so close to its host star, it receives enough insolation to partially melt its surface. However, these past studies failed to take into consideration the role that tides may play in this system. Even if the planet's eccentricity has always been zero, we show that tidal decay of the semimajor axis could have been large enough that the planet formed on a wider orbit which received …
Environmental Crisis And Religious Rhetoric In Is God Green?, Jen Schneider
Environmental Crisis And Religious Rhetoric In Is God Green?, Jen Schneider
Jen Schneider
In the 2006 PBS documentary Is God Green?, Bill Moyers presents the emergence of two key contemporary trends in American political and religious life. The first is the growing popularity of an environmental movement within Christian evangelicalism called 'Creation Care'. Motivated by biblical passages that suggest humans have been 'commissioned' as stewards to care for the earth, or 'God's Body', Creation Care emerged in the late 1970s, gained momentum in the 1990s, and now 'constitutes the "fastest-growing form of Christian ministry"', according to the evangelical publication Christianity Today (Frame 1996:84, see also Psaros 2006:20-32). Is God Green? highlights what …
Inexpensive Time-Lapse Digital Cameras For Studying Transient Meteorological Phenomena: Dust Devils And Playa Flooding, Ralph D. Lorenz, Brian Jackson, Jason W. Barnes
Inexpensive Time-Lapse Digital Cameras For Studying Transient Meteorological Phenomena: Dust Devils And Playa Flooding, Ralph D. Lorenz, Brian Jackson, Jason W. Barnes
Brian Jackson
The authors describe the design and performance of inexpensive and compact time-lapse cameras suitable for field deployment in remote locations for long periods and their application to studying two time-variable meteorological phenomena in arid regions: desert dust devils and transient flooding of playa lakes. The camera units (with a total parts cost of ∼$80) are based around commercial “point and shoot” digital cameras, storing ∼1500 images on a solid-state memory card over a period between an hour to several months powered by alkaline batteries. A microcontroller can trigger image acquisition based on sensor inputs or at regular intervals. Some example …