493 research outputs found
In vivo impact of a 4 bp deletion mutation in the DLX3 gene on bone development
AbstractDistal-less 3 (DLX3) gene mutations are etiologic for Tricho-Dento-Osseous syndrome. To investigate the in vivo impact of mutant DLX3 on bone development, we established transgenic (TG) mice expressing the c.571_574delGGGG DLX-3 gene mutation (MT-DLX3) driven by a mouse 2.3 Col1A1 promoter. Microcomputed tomographic analyses demonstrated markedly increased trabecular bone volume and bone mineral density in femora from TG mice. In ex vivo experiments, TG mice showed enhanced differentiation of bone marrow stromal cells to osteoblasts and increased expression levels of bone formation markers. However, TG mice did not show enhanced dynamic bone formation rates in in vivo fluorochrome double labeling experiments. Osteoclastic differentiation capacities of bone marrow monocytes were reduced in TG mice in the presence of osteoclastogenic factors and the numbers of TRAP(+) osteoclasts on distal metaphyseal trabecular bone surfaces were significantly decreased. TRACP 5b and CTX serum levels were significantly decreased in TG mice, while IFN-γ levels were significantly increased. These data demonstrate that increased levels of IFN-γ decrease osteoclast bone resorption activities, contributing to the enhanced trabecular bone volume and mineral density in these TG mice. These data suggest a novel role for this DLX-3 mutation in osteoclast differentiation and bone resorption
Thermodynamic gauge-theory cascade
It is proposed that the cooling of a thermalized SU() gauge theory can be
formulated in terms of a cascade involving three effective theories with
successively reduced (and spontaneously broken) gauge symmetries, SU()
U(1) Z. The approach is based on the assumption that away
from a phase transition the bulk of the quantum interaction inherent to the
system is implicitly encoded in the (incomplete) classical dynamics of a
collective part made of low-energy condensed degrees of freedom. The properties
of (some of the) statistically fluctuating fields are determined by these
condensate(s). This leads to a quasi-particle description at tree-level. It
appears that radiative corrections, which are sizable at large gauge coupling,
do not change the tree-level picture qualitatively. The thermodynamic
self-consistency of the quasi-particle approach implies nonperturbative
evolution equations for the associated masses. The temperature dependence of
these masses, in turn, determine the evolution of the gauge coupling(s). The
hot gauge system approaches the behavior of an ideal gas of massless gluons at
asymptotically large temperature. A negative equation of state is possible at a
stage where the system is about to settle into the phase of the (spontaneously
broken) Z symmetry.Comment: 25 pages, 6 figures, 1 reference added, minor corrections in text,
errors in Sec. 3.2 corrected, PRD versio
Phenotypic Variation in FAM83H- associated Amelogenesis Imperfecta
FAM83H gene mutations are associated with autosomal-dominant hypocalcified amelogenesis imperfecta (ADHCAI), which is typically characterized by enamel having normal thickness and a markedly decreased mineral content. This study tested the hypothesis that there are phenotype and genotype associations in families with FAM83H-associated ADHCAI. Seven families segregating ADHCAI (147 individuals) were evaluated. Phenotyping included clinical, radiographic, histological, and biochemical studies, and genotyping was by mutational analysis. Multiple novel FAM83H mutations were identified, including two 2-bp-deletion mutations, the first non-nonsense mutations identified. Craniofacial deviation from normal was more prevalent in the affected individuals. Affected individuals having truncating FAMH3H mutations of 677 or fewer amino acids presented a generalized ADHCAI phenotype, while those having mutations capable of producing a protein of at least 694 amino acids had a unique and previously unreported phenotype affecting primarily the cervical enamel. This investigation shows that unique phenotypes are associated with specific FAM83H mutations
On topological charge carried by nexuses and center vortices
In this paper we further explore the question of topological charge in the
center vortex-nexus picture of gauge theories. Generally, this charge is
locally fractionalized in units of 1/N for gauge group SU(N), but globally
quantized in integral units. We show explicitly that in d=4 global topological
charge is a linkage number of the closed two-surface of a center vortex with a
nexus world line, and relate this linkage to the Hopf fibration, with homotopy
; this homotopy insures integrality of the global
topological charge. We show that a standard nexus form used earlier, when
linked to a center vortex, gives rise naturally to a homotopy , a homotopy usually associated with 't Hooft-Polyakov monopoles and similar
objects which exist by virtue of the presence of an adjoint scalar field which
gives rise to spontaneous symmetry breaking. We show that certain integrals
related to monopole or topological charge in gauge theories with adjoint
scalars also appear in the center vortex-nexus picture, but with a different
physical interpretation. We find a new type of nexus which can carry
topological charge by linking to vortices or carry d=3 Chern-Simons number
without center vortices present; the Chern-Simons number is connected with
twisting and writhing of field lines, as the author had suggested earlier. In
general, no topological charge in d=4 arises from these specific static
configurations, since the charge is the difference of two (equal) Chern-Simons
number, but it can arise through dynamic reconnection processes. We complete
earlier vortex-nexus work to show explicitly how to express globally-integral
topological charge as composed of essentially independent units of charge 1/N.Comment: Revtex4; 3 .eps figures; 18 page
Covariant derivative expansion of fermionic effective action at high temperatures
We derive the fermionic contribution to the 1-loop effective action for A_4
and A_i fields at high temperatures, assuming that gluon fields are slowly
varying but allowing for an arbitrary amplitude of A_4.Comment: RevTex 4, 11 pages, 3 figures. Version 2: Typos corrected; magnetic
fields restricted to parallel sector. Version accepted for publication in PR
Covariant derivative expansion of Yang-Mills effective action at high temperatures
Integrating out fast varying quantum fluctuations about Yang--Mills fields
A_i and A_4, we arrive at the effective action for those fields at high
temperatures. Assuming that the fields A_i and A_4 are slowly varying but that
the amplitude of A_4 is arbitrary, we find a non-trivial effective gauge
invariant action both in the electric and magnetic sectors. Our results can be
used for studying correlation functions at high temperatures beyond the
dimensional reduction approximation, as well as for estimating quantum weights
of classical static configurations such as dyons.Comment: Minor changes. References added. Paper accepted for publication in
Phys.Rev.
An Experimental Investigation of Colonel Blotto Games
"This article examines behavior in the two-player, constant-sum Colonel Blotto game with asymmetric resources in which players maximize the expected number of battlefields won. The experimental results support all major theoretical predictions. In the auction treatment, where winning a battlefield is deterministic, disadvantaged players use a 'guerilla warfare' strategy which stochastically allocates zero resources to a subset of battlefields. Advantaged players employ a 'stochastic complete coverage' strategy, allocating random, but positive, resource levels across the battlefields. In the lottery treatment, where winning a battlefield is probabilistic, both players divide their resources equally across all battlefields." (author's abstract)"Dieser Artikel untersucht das Verhalten von Individuen in einem 'constant-sum Colonel Blotto'-Spiel zwischen zwei Spielern, bei dem die Spieler mit unterschiedlichen Ressourcen ausgestattet sind und die erwartete Anzahl gewonnener Schlachtfelder maximieren. Die experimentellen Ergebnisse bestätigen alle wichtigen theoretischen Vorhersagen. Im Durchgang, in dem wie in einer Auktion der Sieg in einem Schlachtfeld deterministisch ist, wenden die Spieler, die sich im Nachteil befinden, eine 'Guerillataktik' an, und verteilen ihre Ressourcen stochastisch auf eine Teilmenge der Schlachtfelder. Spieler mit einem Vorteil verwenden eine Strategie der 'stochastischen vollständigen Abdeckung', indem sie zufällig eine positive Ressourcenmenge auf allen Schlachtfeldern positionieren. Im Durchgang, in dem sich der Gewinn eines Schlachtfeldes probabilistisch wie in einer Lotterie bestimmt, teilen beide Spieler ihre Ressourcen gleichmäßig auf alle Schlachtfelder auf." (Autorenreferat
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