Results 131 to 140 of about 16,133 (302)

Evaluating maturity of organic matter in hydrated C1 and CM‐like clasts and a dehydrated clast within a polymict eucrite and a howardite

Meteoritics &Planetary Science, EarlyView.
Abstract Volatile‐rich xenolithic clasts in different types of brecciated meteorites represent unique pristine solar system material. This study investigates the maturity and thermal history of organic matter using Raman spectroscopy and aqueous alteration effects using infrared spectroscopy in the matrix of 15 volatile‐rich clasts (C1 and CM‐like ...
Swarna Prava Das, Alessandro Maturilli, Aurélie Van den Neucker, Markus Patzek, Dipak Kumar Panda, Gopal K. Pradhan, Guneshwar Thangjam, Surya Snata Rout   +7 more
wiley   +1 more source

Quadrupole formulae with cosmological constant: comparison

Journal of High Energy Physics
We consider three different approaches (by Ashtekar, Bonga and Kesavan; Hoque and Virmani; and Dobkowski-Ryłko and Lewandowski) to investigate gravitational radiation produced by time changing matter source in de Sitter spacetime.
Denis Dobkowski-Ryłko, Jerzy Lewandowski   +1 more
doaj   +1 more source

Cosmological constant [PDF]

, 2017
The contribution of vacuum fluctuations to the cosmological constant is reconsidered studying the dependence on the used regularisation scheme. Then alternative explanations for the observed accelerated expansion of the universe in the present epoch are ...
Michael Kachelriess
core   +1 more source

The Ames impact structure, Oklahoma: New radioisotopic constraints and implications for North American impact chronology

Meteoritics &Planetary Science, EarlyView.
Abstract The Ames impact structure (Oklahoma) is thought to have formed during the Ordovician Meteor Event, based on conodont biostratigraphy of its crater fill. Here, U–Pb zircon dates from its impact‐melt portion, conducted using secondary ion mass spectrometry and laser ablation–inductively coupled plasma–mass spectrometry (n = 37 spots), yield a ...
Elizabeth J. Catlos, Andrew F. Parisi, Michael E. Brookfield, Timmons Erickson, Sean P.S. Gulick, Axel K. Schmitt, Daniel F. Stockli, Daniel P. Miggins, Ben Ruchte, Mark Cloos   +9 more
wiley   +1 more source

Nanoscale space weathering features in mature lunar soil revealed by TEM and APT

Meteoritics &Planetary Science, EarlyView.
Abstract Space weathering significantly alters the optical, chemical, and structural properties of lunar regolith at micro‐ and nanoscales; yet detailed nanoscale variability within individual soils remains underexplored. Here we apply transmission electron microscopy (TEM) and atom probe tomography to four mineral grains (olivine, ilmenite, and two ...
Jennika Greer, Alexander M. Kling, Luke Daly, Dieter Isheim, David N. Seidman, Michelle S. Thompson, Philipp R. Heck   +6 more
wiley   +1 more source

The 40K‐K dating system: 1. Improving data interpretation using new model calculations

Meteoritics &Planetary Science, EarlyView.
Abstract The 40K‐K cosmic‐ray exposure (CRE) dating system offers a promising method for determining exposure ages of iron meteorites by combining the radioactive cosmogenic 40K with the stable cosmogenic isotopes 39K and 41K. However, earlier applications relied on semi‐empirical production models and inconsistent analytical data sets, limiting their ...
Farshid Nozarian, Suzette Timmerman, Ingo Leya   +2 more
wiley   +1 more source

Hybrid imploding scalar and ads spacetime

Physics Letters B, 2019
A solution to the massless scalar cosmological constant field equations is presented. The solution has imploding scalar and parts of anti-deSitter or deSitter spacetime as limiting cases.
Mark D. Roberts
doaj   +1 more source

Challenging the Cosmological Constant [PDF]

, 2012
Kaloper, Nemanja. (2012). Challenging the Cosmological Constant.
Kaloper, Nemanja
core  

Microstructural evidence for multiple generations of sulfide precipitation and impact‐induced thermal alteration under acidic conditions on Asteroid Ryugu

Meteoritics &Planetary Science, EarlyView.
Abstract Here we report on the microstructure and chemistry of sulfide minerals returned from asteroid (162173) Ryugu. We identify a unique sulfide population in particle A0016 composed of violarite (FeNi2S4), pyrite (FeS2), chalcopyrite (CuFeS2), pyrrhotite (Fe1‐xS), and pentlandite ([Fe,Ni]9S8).
M. C. Benner, B. S. Prince, D. L. Schrader, T. J. Zega   +3 more
wiley   +1 more source

“We Have Come to Offer Something Which (They) Were Not Even Looking for”: U.S. Christian Conservative Evangelical Faith Missions in the Ecuadorian Upper Amazon

The Journal of American Culture, EarlyView.
Diego Mauricio Cortés
wiley   +1 more source