12 research outputs found
Gravitoelectromagnetic inflation from a 5D vacuum state: a new formalism
We propose a novel formalism for inflation from a 5D vacuum state which could
explain both, seeds of matter and magnetic fields in the early universe.Comment: final version (figure included
Plane-symmetric inhomogeneous magnetized viscous fluid universe with a variable
The behavior of magnetic field in plane symmetric inhomogeneous cosmological
models for bulk viscous distribution is investigated. The coefficient of bulk
viscosity is assumed to be a power function of mass density . The values of cosmological constant for these models are
found to be small and positive which are supported by the results from recent
supernovae Ia observations. Some physical and geometric aspects of the models
are also discussed.Comment: 18 pages, LaTex, no figur
The Interstellar Environment of our Galaxy
We review the current knowledge and understanding of the interstellar medium
of our galaxy. We first present each of the three basic constituents - ordinary
matter, cosmic rays, and magnetic fields - of the interstellar medium, laying
emphasis on their physical and chemical properties inferred from a broad range
of observations. We then position the different interstellar constituents, both
with respect to each other and with respect to stars, within the general
galactic ecosystem.Comment: 39 pages, 12 figures (including 3 figures in 2 parts
Magnetic Fields in the Early Universe
This review concerns the origin and the possible effects of magnetic fields
in the early Universe. We start by providing to the reader with a short
overview of the current state of art of observations of cosmic magnetic fields.
We then illustrate the arguments in favour of a primordial origin of magnetic
fields in the galaxies and in the clusters of galaxies. We argue that the most
promising way to test this hypothesis is to look for possible imprints of
magnetic fields on the temperature and polarization anisotropies of the cosmic
microwave background radiation (CMBR). With this purpose in mind, we provide a
review of the most relevant effects of magnetic fields on the CMBR. A long
chapter of this review is dedicated to particle physics inspired models which
predict the generation of magnetic fields during the early Universe evolution.
Although it is still unclear if any of these models can really explain the
origin of galactic and intergalactic magnetic fields, we show that interesting
effects may arise anyhow. Among these effects, we discuss the consequences of
strong magnetic fields on the big-bang nucleosynthesis, on the masses and
couplings of the matter constituents, on the electroweak phase transition, and
on the baryon and lepton number violating sphaleron processes. Several
intriguing common aspects, and possible interplay, of magnetogenesis and
baryogenesis are also dicussed.Comment: 152 LaTeX pages, 6 figures., final version to appear in Phys. Re
Origin of Galactic and Extragalactic Magnetic Fields
A variety of observations suggest that magnetic fields are present in all
galaxies and galaxy clusters. These fields are characterized by a modest
strength (10^{-7}-10^{-5} G) and huge spatial scale (~Mpc). It is generally
assumed that magnetic fields in spiral galaxies arise from the combined action
of differential rotation and helical turbulence, a process known as the
alpha-omega dynamo. However fundamental questions concerning the nature of the
dynamo as well as the origin of the seed fields necessary to prime it remain
unclear. Moreover, the standard alpha-omega dynamo does not explain the
existence of magnetic fields in elliptical galaxies and clusters. The author
summarizes what is known observationally about magnetic fields in galaxies,
clusters, superclusters, and beyond. He then reviews the standard dynamo
paradigm, the challenges that have been leveled against it, and several
alternative scenarios. He concludes with a discussion of astrophysical and
early Universe candidates for seed fields.Comment: 67 pages, 17 figures, accepted for publication in Reviews of Modern
Physic
Harnessing Food Product Reviews for Personalizing Sweetness Levels
Sweet taste is innately appealing, ensuring that mammals are attracted to the sweetness of mother’s milk and other sources of carbohydrates and calories. In the modern world, the availability of sugars and sweeteners and the eagerness of the food industry to maximize palatability, result in an abundance of sweet food products, which poses a major health challenge. The aim of the current study is to analyze sweetness levels, liking, and ingredients of online reviews of food products, in order to obtain insights into sensory nutrition and to identify new opportunities for reconciling the palatability–healthiness tension. We collected over 200,000 reviews of ~30,000 products on Amazon dated from 2002 to 2012 and ~350,000 reviews of ~2400 products on iHerb from 2006 to 2021. The reviews were classified and analyzed using manual curation, natural language processing, and machine learning. In total, ~32,000 (Amazon) and ~29,000 (iHerb) of these reviews mention sweetness, with 2200 and 4600 reviews referring to the purchased products as oversweet. Oversweet reviews were dispersed among consumers. Products that included sucralose had more oversweet reviews than average. 26 products had at least 50 reviews for which at least 10% were oversweet. For these products, the average liking by consumers reporting oversweetness was significantly lower (by 0.9 stars on average on a 1 to 5 stars scale) than by the rest of the consumers. In summary, oversweetness appears in 7–16% of the sweetness-related reviews and is less liked, which suggests an opportunity for customized products with reduced sweetness. These products will be simultaneously healthier and tastier for a substantial subgroup of customers and will benefit the manufacturer by expanding the products’ target audience. Analysis of consumers’ reviews of marketed food products offers new ways to obtain informative sensory data