2,558 research outputs found
Low-energy Phenomenology Of Scalarless Standard-Model Extensions With High-Energy Lorentz Violation
We consider renormalizable Standard-Model extensions that violate Lorentz
symmetry at high energies, but preserve CPT, and do not contain elementary
scalar fields. A Nambu--Jona-Lasinio mechanism gives masses to fermions and
gauge bosons, and generates composite Higgs fields at low energies. We study
the effective potential at the leading order of the large-N_{c} expansion,
prove that there exists a broken phase and study the phase space. In general,
the minimum may break invariance under boosts, rotations and CPT, but we give
evidence that there exists a Lorentz invariant phase. We study the spectrum of
composite bosons and the low-energy theory in the Lorentz phase. Our approach
predicts relations among the parameters of the low-energy theory. We find that
such relations are compatible with the experimental data, within theoretical
errors. We also study the mixing among generations, the emergence of the CKM
matrix and neutrino oscillations.Comment: 32 pages; v2: typos corrected, more references, some more comments -
PR
Human Capital Externalities and Private Returns to Education in Kenya
We use survey data of full-time workers in Kenya to analyse the effect of human capital externalities on earnings and private returns to education. The estimation results show that education human capital generally associates with positive externalities, indicating that an increase in education benefits all workers. However, the results reveal that men benefit more from women's education than women do from men's schooling. The effects of human capital externalities on private returns to schooling are shown to vary substantially between rural and urban areas and across primary and higher levels of education.
Renormalization of a class of non-renormalizable theories
Certain power-counting non-renormalizable theories, including the most
general self-interacting scalar fields in four and three dimensions and
fermions in two dimensions, have a simplified renormalization structure. For
example, in four-dimensional scalar theories, 2n derivatives of the fields,
n>1, do not appear before the nth loop. A new kind of expansion can be defined
to treat functions of the fields (but not of their derivatives)
non-perturbatively. I study the conditions under which these theories can be
consistently renormalized with a reduced, eventually finite, set of independent
couplings. I find that in common models the number of couplings sporadically
grows together with the order of the expansion, but the growth is slow and a
reasonably small number of couplings is sufficient to make predictions up to
very high orders. Various examples are solved explicitly at one and two loops.Comment: 38 pages, 1 figure; v2: more explanatory comments and references;
appeared in JHE
Infinite reduction of couplings in non-renormalizable quantum field theory
I study the problem of renormalizing a non-renormalizable theory with a
reduced, eventually finite, set of independent couplings. The idea is to look
for special relations that express the coefficients of the irrelevant terms as
unique functions of a reduced set of independent couplings lambda, such that
the divergences are removed by means of field redefinitions plus
renormalization constants for the lambda's. I consider non-renormalizable
theories whose renormalizable subsector R is interacting and does not contain
relevant parameters. The "infinite" reduction is determined by i) perturbative
meromorphy around the free-field limit of R, or ii) analyticity around the
interacting fixed point of R. In general, prescriptions i) and ii) mutually
exclude each other. When the reduction is formulated using i), the number of
independent couplings remains finite or slowly grows together with the order of
the expansion. The growth is slow in the sense that a reasonably small set of
parameters is sufficient to make predictions up to very high orders. Instead,
in case ii) the number of couplings generically remains finite. The infinite
reduction is a tool to classify the irrelevant interactions and address the
problem of their physical selection.Comment: 40 pages; v2: more explanatory comments; appeared in JHE
Transcription activator like effector (TALE)-directed piggyBac transposition in human cells.
Insertional therapies have shown great potential for combating genetic disease and safer methods would undoubtedly broaden the variety of possible illness that can be treated. A major challenge that remains is reducing the risk of insertional mutagenesis due to random insertion by both viral and non-viral vectors. Targetable nucleases are capable of inducing double-stranded breaks to enhance homologous recombination for the introduction of transgenes at specific sequences. However, off-target DNA cleavages at unknown sites can lead to mutations that are difficult to detect. Alternatively, the piggyBac transposase is able perform all of the steps required for integration; therefore, cells confirmed to contain a single copy of a targeted transposon, for which its location is known, are likely to be devoid of aberrant genomic modifications. We aimed to retarget transposon insertions by comparing a series of novel hyperactive piggyBac constructs tethered to a custom transcription activator like effector DNA-binding domain designed to bind the first intron of the human CCR5 gene. Multiple targeting strategies were evaluated using combinations of both plasmid-DNA and transposase-protein relocalization to the target sequence. We demonstrated user-defined directed transposition to the CCR5 genomic safe harbor and isolated single-copy clones harboring targeted integrations
Strontium isopropoxide: a highly active catalyst for the ringâopening polymerization of lactide and various lactones
Abstract Commercially available strontium isopropoxide represents a suitable catalyst/initiator for the ringâopening polymerization (ROP) of lactide (LA), Δâcaprolactone, ÎŽâvalerolactone, ÎŽâcaprolactone, and ÎŽâdecalactone. Wellâdefined polyesters are accessible via the solution polymerization of lactide in toluene with a [LA]:[Sr] ratio of 100:1 at room temperature with or without the addition of dodecanol as coinitiator. Kinetic studies and detailed analysis by means of matrixâassisted laser desorption ionization mass spectrometry reveal pseudoâfirstâorder kinetics of the ROP as well as excellent endgroup fidelity of the polylactide (PLA) with isopropyl and dodecyl αâendgroups. Both isopropanolate moieties as well as the coinitiator each initiate PLA chains, enabling the synthesis of PLA with tailored molar mass. The polymerization of Δâcaprolactone and ÎŽâvalerolactone confirms the high catalyst activity, which causes quantitative monomer conversion after 1 min polymerization time but broad molar mass distributions. In contrast, the catalyst is well suited for the ROP of the less reactive ÎŽâcaprolactone and ÎŽâdecalactone. Although kinetic studies reveal initially bimodal molar mass distributions, polyesters with dispersity values Ă < 1.2 and unimodal molar mass distributions can be obtained at moderate to high monomer conversions
Basic Human Values and Moral Foundations Theory in ValueNet Ontology
Values, as intended in ethics, determine the shape and validity of moral and social norms, grounding our everyday individual and community behavior on commonsense knowledge. The attempt to untangle human moral and social value-oriented structure of relations requires investigating both the dimension of subjective human perception of the world, and socio-cultural dynamics and multi-agent social interactions. Formalising latent moral content in human interaction is an appealing perspective that would enable a deeper understanding of both social dynamics and individual cognitive and behavioral dimension. To formalize this broad knowledge area, in the context of ValueNet, a modular ontology representing and operationalising moral and social values, we present two modules aiming at representing two main informal theories in literature: (i) the Basic Human Values theory by Shalom Schwartz and (ii) the Moral Foundations Theory by Graham and Haidt. ValueNet is based on reusable Ontology Design Patterns, is aligned to the DOLCE foundational ontology, and is a component of the Framester factual-linguistic knowledge graph
Plasma 2020 - Intracluster Medium Plasmas
Galaxy clusters are the largest and most massive bound objects resulting from
cosmic hierarchical structure formation. Baryons account for somewhat more than
10% of that mass, with roughly 90% of the baryonic matter distributed
throughout the clusters as hot ( keV), high-, very weakly
collisional plasma; the so-called "intracluster medium" (ICM). Cluster mergers,
close gravitational encounters and accretion, along with violent feedback from
galaxies and relativistic jets from active galactic nuclei, drive winds,
gravity waves, turbulence and shocks within the ICM. Those dynamics, in turn,
generate cluster-scale magnetic fields and accelerate and mediate the transport
of high-energy charged particles. Kinetic-scale, collective plasma processes
define the basic character and fundamental signatures of these ICM phenomena,
which are observed primarily by X-ray and radio astronomers.Comment: 5 pages, 2 figures, submitted for the 2020 Decadal Assessment of
Plasma Scienc
- âŠ