Einstein’s version of dark energy is known as the cosmological constant. It implies a fixed amount of dark energy in each ...
The general applicability of solution NMR spectroscopy to structural characterization of intact α-helical membrane proteins has been demonstrated by a number of recent studies. Examples include the ...
Dive into PNAS Front Matter for editorials, interviews, science news, and commentary that offer expert perspective on today’s most important research findings.
Journal Club posts are short news stories featuring a recent important, timely journal article selected by one of our Journal Club panelists, who are post-doctoral associates and graduate students in ...
This finding documents smoke-dried mummification of the dead, mostly in tightly bound crouched postures, from archaeological ...
Phonon softening and crystallographic orientation of strained graphene studied by Raman spectroscopy
We present a systematic study of the Raman spectra of optical phonons in graphene monolayers under tunable uniaxial tensile stress. Both the G and 2D bands exhibit significant red shifts. The G band ...
Wildfires are a major source of fine particulate matter (diameter <2.5 µm; PM 2.5), which is a health hazard. Since the mid-1980s, the total US area burned by wildfires has been increasing, with fires ...
Open in Viewer (A) Schematic of a photocell consisting of quantum dots sandwiched between p and n doped semiconductors. Open circuit voltage and solar photon energy ℏνh are related by the Carnot ...
Open in Viewer Evolution of atmospheric CO 2 (a), methane (b), and nitrous oxide (c), and sampling intervals (d) over the past 20,000 years. The gray bar denotes the range of the preindustrial, ...
Edited by G. Philip Robertson, W. K. Kellogg Biological Station, Hickory Corners, MI, and accepted by the Editorial Board May 4, 2010 (received for review December 9, 2009) The second counterfactual ...
Edited by Peter H. Gleick, Pacific Institute for Studies in Development, Environment, and Security, Oakland, CA, and approved December 21, 2011 (received for review June 20, 2011) In formulating ...
We show that for thousands of years, humans have concentrated in a surprisingly narrow subset of Earth’s available climates, characterized by mean annual temperatures around ∼13 °C. This distribution ...
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