1,242 research outputs found
Effects of the 1964 Alaskan Earthquake on Glaciers and Related Features
Describes an aerial photographic reconnaissance in Apr and Sept 1964 of the approx 30,000 sq mi area most seriously affected by the Mar 27 earthquake to assess the extent to which glacial features had been modified. Little change was apparent in glacial basins, lakes or tidewater calving, much less than after the 1899 and 1958 earthquakes of comparable violence. Some rock slides on to glaciers were impressive. The effects are related to the Tarr and Martin (No 17449) theory of earthquake avalanche supply, but it may be several years before evidence to test the applicability of the theory to the 1964 earthquake is apparent. 25 air photos with detailed descriptive notes illus the features described. Condensed version of the text was pub in Arctic 1965. v 18, no 2, p. 135-37
New land-use-change emissions indicate a declining CO<sub>2</sub> airborne fraction
About half of the anthropogenic CO2 emissions remain in the atmosphere and half are taken up by the land and ocean1. If the carbon uptake by land and ocean sinks becomes less efficient, for example, owing to warming oceans2 or thawing permafrost3, a larger fraction of anthropogenic emissions will remain in the atmosphere, accelerating climate change. Changes in the efficiency of the carbon sinks can be estimated indirectly by analysing trends in the airborne fraction, that is, the ratio between the atmospheric growth rate and anthropogenic emissions of CO2 (refs. 4–10). However, current studies yield conflicting results about trends in the airborne fraction, with emissions related to land use and land cover change (LULCC) contributing the largest source of uncertainty7,11,12. Here we construct a LULCC emissions dataset using visibility data in key deforestation zones. These visibility observations are a proxy for fire emissions13,14, which are — in turn — related to LULCC15,16. Although indirect, this provides a long-term consistent dataset of LULCC emissions, showing that tropical deforestation emissions increased substantially (0.16 Pg C decade−1) since the start of CO2 concentration measurements in 1958. So far, these emissions were thought to be relatively stable, leading to an increasing airborne fraction4,5. Our results, however, indicate that the CO2 airborne fraction has decreased by 0.014 ± 0.010 decade−1 since 1959. This suggests that the combined land–ocean sink has been able to grow at least as fast as anthropogenic emissions
Life and death at precolumbian Lavoutte, Saint Lucia, Lesser Antilles
The Caribbean archaeological record requires immediate attention and protection. Development and natural forces have impacted archaeological sites, destroying or severely damaging them. The precolumbian site of Lavoutte, located in northern Saint Lucia, has been known as a major Late Ceramic Age (A.D. 1000–1500) settlement since the 1960s, but it has been damaged over the past decades by both natural and human processes. Multidisciplinary field and laboratory methodologies were implemented during a rescue project at the site from 2009 to 2010. This paper presents the results of collaborative efforts between local and international organizations. The first goal was to demonstrate the importance of protection and rescue of endangered archaeological sites. Secondly, we aimed to show that by adopting a
multidisciplinary approach including artifact analysis, bioarchaeology, paleoenvironmental reconstruction, and geochemistry, severely damaged sites can be of significant informational value. Archaeology of indigenous Americ
Successful Strategies for Promoting Self-Advocacy Among Students with LD: The LEAD Group
Students with learning disabilities (LD) often need to be taught self-determination skills to be better prepared for life after high school. This article describes the methods used by one school district to promote self-advocacy and self-awareness skills for students with LD. Through multicomponent group activities, students learned about their strengths and disabilities and how to advocate for their educational needs and rights. Advocacy skills were also applied to leadership roles, mentoring, and community education activities. Important features that contributed to the success of the program are described.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
Interference-induced gain in Autler-Townes doublet of a V-type atom in a cavity
We study the Autler-Townes spectrum of a V-type atom coupled to a
single-mode, frequency-tunable cavity field at finite termperature, with a
pre-selected polarization in the bad cavity limit, and show that, when the mean
number of thermal photons and the excited sublevel splitting is very
large (the same order as the cavity linewidth), the probe gain may occur at
either sideband of the doublet, depending on the cavity frequency, due to the
cavity-induced interference.Comment: Minor changes are mad
Controlling laser spectra in a phaseonium photonic crystal using maser
We study the control of quantum resonances in photonic crystals with
electromagnetically induced transparency driven by microwave field. In addition
to the control laser, the intensity and phase of the maser can alter the
transmission and reflection spectra in interesting ways, producing hyperfine
resonances through the combined effects of multiple scattering in the
superstructure.Comment: 7 pages, 4 figure
Cavity implementation of quantum interference in a -type atom
A scheme for engineering quantum interference in a -type atom
coupled to a frequency-tunable, single-mode cavity field with a pre-selected
polarization at finite temperature is proposed. Interference-assisted
population trapping, population inversions and probe gain at one sideband of
the Autler-Townes spectrum are predicted for certain cavity resonant
frequencies.Comment: 2 postscript figures are adde
Compact jets as probes for sub-parsec scale regions in AGN
Compact relativistic jets in active galactic nuclei offer an effective tool
for investigating the physics of nuclear regions in galaxies. The emission
properties, dynamics, and evolution of jets in AGN are closely connected to the
characteristics of the central supermassive black hole, accretion disk and
broad-line region in active galaxies. Recent results from studies of the
nuclear regions in several active galaxies with prominent outflows are reviewed
in this contribution.Comment: AASLaTeX, 5 pages, 4 figures. Accepted in Astrophysics and Space
Scienc
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