5,413 research outputs found
On the quantum stress tensor for extreme 2D Reissner-Nordstrom black holes
Contrary to previous claims, it is shown that the expectation values of the
quantum stress tensor for a massless scalar field propagating on a
two-dimensional extreme Reissner-Nordstrom black hole are indeed regular on the
horizon.Comment: 5 pages, revtex, 1 figur
Carbonaceous materials : the beauty of simplicity
The current mandates of a sustainable society and circular economy lead to the request that materials chemistry, but also chemistry as such, has to become significantly redesigned. Changes include commonplaces as the glassware we use, the minimization of wastes and side products or replacement strategies in the materials choice, among others. In this context, âcarbonsâ are very versatile and already have found their place in a myriad of applications for a âcarbon-neutralâ society. They already take key enabling positions for sensors and biomaterials preparation, as energy conversion and storage electrode, or as effluent remediation sorbents. Herein, we describe how carbon chemistry can be again re-designed to outperform benchmark materials in a number of fields, especially in energy storage, (electro)catalysis, as sorbent, but also in a new chemistry of the confined state
Participatory varietal selection of potato using the mother & baby trial design: A gender-responsive trainerâs guide.
This guide aims to provide step-by-step guidance on facilitating and documenting the PVS dynamics using the MBT design to select, and eventually release, potato varieties preferred by end-users that suit male and female farmers âdifferent needs, diverse agro-systems, and management practices, as well as traders âand consumersâ preferences
Limitations on the superposition principle: superselection rules in non-relativistic quantum mechanics
The superposition principle is a very basic ingredient of quantum theory.
What may come as a surprise to many students, and even to many practitioners of
the quantum craft, is tha superposition has limitations imposed by certain
requirements of the theory. The discussion of such limitations arising from the
so-called superselection rules is the main purpose of this paper. Some of their
principal consequences are also discussed. The univalence, mass and particle
number superselection rules of non-relativistic quantum mechanics are also
derived using rather simple methods.Comment: 22 pages, no figure
Test of nuclear level density inputs for Hauser-Feshbach model calculations
The energy spectra of neutrons, protons, and alpha-particles have been
measured from the d+59Co and 3He+58Fe reactions leading to the same compound
nucleus, 61$Ni. The experimental cross sections have been compared to
Hauser-Feshbach model calculations using different input level density models.
None of them have been found to agree with experiment. It manifests the serious
problem with available level density parameterizations especially those based
on neutron resonance spacings and density of discrete levels. New level
densities and corresponding Fermi-gas parameters have been obtained for
reaction product nuclei such as 60Ni,60Co, and 57Fe
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