Results 41 to 50 of about 228,090 (281)

Time variation of the fine structure constant in the early universe and the Bekenstein model [PDF]

, 2007
We calculate bounds on the variation of the fine structure constant at the time of primordial nucleosynthesis and at the time of neutral hydrogen formation. We use these bounds and other bounds from the late universe to test Bekenstein model.
Antoniadis, Asplund, Bachas, Bahcall, Barr, Barrow, Bekenstein, Benjamin, Bergström, Bize, Bonifacio, Bonifacio, Bonifacio, Bonifacio, Brax, Burles, Burles, C. G. Scóccola, Chamoun, Chamoun, Chamoun, Chand, Coc, Coc, Cole, Cowie, Crighton, Cuoco, Cyburt, Cyburt, Damour, Damour, Damour, Damour, Darling, Dirac, Dmitriev, Fischer, Freedman, Fujii, Gleiser, Grupe, H. Vucetich, Ichikawa, Ichikawa, Ichikawa, Izotov, Jones, Kaluza, Kanekar, Khatri, Kirkman, Klein, Kuo, Lamoreaux, Landau, Landau, Levshakov, Lewis, Lewis, M. E. Mosquera, Maeda, Marion, Martins, Martínez Fiorenzano, Murphy, Murphy, Murphy, Murphy, Müller, Nollett, O'Meara, O'Meara, Olive, Olive, Olive, Oliveira, Overduin, Palma, Peik, Peimbert, Pettini, Piacentini, Porter, Prestage, Quast, Readhead, Rocha, Ryan, S. J. Landau, Sanchez, Sandvik, Seager, Sisterna, Sortais, Spergel, Spinrad, Srianand, Tzanavaris, Varshalovich, Webb, Webb, Weinberg, Wolfe, Wu, Youm, Youm   +106 more
core   +3 more sources

Comparative Study of Experimental Methods for Measuring Thermal Properties of 100Cr6 Steel Powders

Advanced Engineering Materials, EarlyView.
This study investigates the thermal properties of 100Cr6 steel in both bulk and powder forms. Measuring the very low thermal conductivity typically exhibited by powders poses significant challenges. To address this, two novel measurement techniques—temperature gradient and finite laser pulse response—are introduced and evaluated by comparison with the ...
Junsheng Zhuo, Hagen P. Kohl, Dongmei Liu, Lisa Matthäus, Arne Bochmann, Aaron Berger, Sebastian Weber, Stefan Nolte, Stephanie Lippmann   +8 more
wiley   +1 more source

Inexpensive DIY Magnetometer Designs for Formal and Informal Investigations of Geomagnetic Sq Variations and Space Weather Events

IEEE Access
Simple magnetometers are the gateway instruments for exploring the geomagnetic field that can be used by hobbyists and teachers alike to monitor and study a variety of space weather phenomena.
Sten Odenwald, Hilarie Davis, Christina Milotte, Cris L. DeWolf   +3 more
doaj   +1 more source

Narrow-Band Spectrophotometry of Comet Hale-Bopp (C/1995 O1) Near Perihelion I.: Photometric Behavior of C2, C3, CN Molecular Bands [PDF]

Journal of Astronomy and Space Sciences, 2000
We present the results from narrow-band spectrophotometry of Comet Hale-Bopp (C/1995 O1) near perihelion obtained at Sobaeksan Optical Astronomy Observatory 61cm telescope equipped with PM 512 CCD camera (512 x 512, 0.5''/pixel) and narrow-band filter ...
Eon-Chang Sung, Ho-Il Kim, Jae Hyuk Youn
doaj  

3D Printed Ultra‐Fast Plastic Scintillators Based on Perovskite‐Photocurable Polymer Composite

Advanced Functional Materials, Volume 35, Issue 12, March 18, 2025.
The demand for radiation detection is increasing in a number of fields, including high‐energy physics, medical imaging, and homeland security. This study serves to demonstrate the potential for the fabrication of fast perovskite‐based scintillators with complex shapes via stereolithographic additive manufacturing, representing a new path toward the ...
Antonella Giuri, Amal C Chekkallur, Mario Calora, Rosanna Mastria, Loris Martinazzoli, Etiennette Auffray, Sanosh Kunjalukkal Padmanabhan, Sara Carturan, Sandra Moretto, Gianluca Quarta, Lucio Calcagnile, Matteo Polo, Alberto Quaranta, Alfonso Maffezzoli, Anna Paola Caricato, Aurora Rizzo, Carola Esposito Corcione   +16 more
wiley   +1 more source

Chemical Homogeneity of Wide Binary Systems: An Approach from Near-Infrared Spectroscopy

The Astronomical Journal, 2023
Wide binaries, with separations between the two stars from a few au to more than several thousand au, are valuable objects for various research topics in Galactic astronomy.
Dongwook Lim, Andreas J. Koch-Hansen, Seungsoo Hong, Sang-Hyun Chun, Young-Wook Lee   +4 more
doaj   +1 more source

No magnetic field variation with pulsation phase in the roAp star gamma Equulei

, 2004
We present an analysis of 210 high-resolution time-resolved spectropolarimetric observations of the roAp star gamma Equ obtained over three nights in August and September 2003.
Kochukhov, O., Piskunov, N., Ryabchikova, T.   +2 more
core   +1 more source

ErMn6Sn6: A Promising Kagome Antiferromagnetic Candidate for Room‐Temperature Nernst Effect‐Based Thermoelectrics

Advanced Functional Materials, EarlyView.
This work investigates the Nernst effect in the Kagome magnet ErMn6Sn6 which exhibits both topological and anomalous Nernst effects with the anomalous Nernst coefficient reaching 1.71 µV K⁻¹ at 300 K. This value surpasses that of most canted antiferromagnetic materials, making ErMn6Sn6 a promising candidate for advancing thermoelectric devices based on
Olajumoke Oluwatobiloba Emmanuel, Shuvankar Gupta, Xianglin Ke   +2 more
wiley   +1 more source

Exoplanet Ephemerides Change Observations (ExoEcho). II. Transit Timing Variation Analysis of Brown Dwarfs around Solar-type Stars

The Astrophysical Journal
Transit timing variation (TTV) is a useful tool for studying the orbital properties of transiting objects. However, few TTV studies have been done on transiting brown dwarfs (BDs) around solar-type stars.
Wenqin Wang, Xinyue Ma, Zhangliang Chen, Cong Yu, Shangfei Liu, Bo Ma   +5 more
doaj   +1 more source

Constraints on time variation of fine structure constant from WMAP-3yr data

, 2007
This paper presents the constraints on the time variation of the fine structure constant at recombination relative to its present value, Delta_alpha = (alpha_rec-alpha_0) / alpha_0, obtained from the analysis of the WMAP-3yr Cosmic Microwave Background ...
Stefanescu, Petruta
core   +1 more source