29 research outputs found
Expanded Monomeric Intermediate upon Cold and Heat Unfolding of Phosphofructokinase-2 from Escherichia coli
AbstractFolding studies have been focused mainly on small, single-domain proteins or isolated single domains of larger proteins. However, most of the proteins present in biological systems are composed of multiple domains, and to date, the principles that underlie its folding remain elusive. The unfolding of Pfk-2 induced by GdnHCl has been described by highly cooperative three-state equilibrium (N2â2Iâ2U). This is characterized by a strong coupling between the subunitsâ tertiary structure and the integrity of the dimer interface because âIâ represents an unstructured and expanded monomeric intermediate. Here we report that cold and heat unfolding of Pfk-2 resembles the N2â2I step of chemically induced unfolding. Moreover, cold unfolding appears to be as cooperative as that induced chemically and even more so than its heat-unfolding counterpart. Because Pfk-2 is a large homodimer of 66Â kDa with a complex topology consisting of well-defined domains, these results are somewhat unexpected considering that cold unfolding has been described as a special kind of perturbation that decouples the cooperative unfolding of several proteins
Scalar Field Theory on Fuzzy S^4
Scalar fields are studied on fuzzy and a solution is found for the
elimination of the unwanted degrees of freedom that occur in the model. The
resulting theory can be interpreted as a Kaluza-Klein reduction of CP^3 to S^4
in the fuzzy context.Comment: 16 pages, LaTe
Octonion Quantum Chromodynamics
Starting with the usual definitions of octonions, an attempt has been made to
establish the relations between octonion basis elements and Gell-Mann \lambda
matrices of SU(3)symmetry on comparing the multiplication tables for Gell-Mann
\lambda matrices of SU(3)symmetry and octonion basis elements. Consequently,
the quantum chromo dynamics (QCD) has been reformulated and it is shown that
the theory of strong interactions could be explained better in terms of
non-associative octonion algebra. Further, the octonion automorphism group
SU(3) has been suitably handled with split basis of octonion algebra showing
that the SU(3)_{C}gauge theory of colored quarks carries two real gauge fields
which are responsible for the existence of two gauge potentials respectively
associated with electric charge and magnetic monopole and supports well the
idea that the colored quarks are dyons
Quaternion-Octonion Unitary Symmetries and Analogous Casimir Operators
An attempt has been made to investigate the global SU(2) and SU(3) unitary
flavor symmetries systematically in terms of quaternion and octonion
respectively. It is shown that these symmetries are suitably handled with
quaternions and octonions in order to obtain their generators, commutation
rules and symmetry properties. Accordingly, Casimir operators for SU(2)and
SU(3) flavor symmetries are also constructed for the proper testing of these
symmetries in terms of quaternions and octonions
Is The Amphibian Tree of Life really fatally flawed?
Wiens (2007 , Q. Rev. Biol. 82, 55â56) recently published a severe critique of Frost et al.'s (2006, Bull. Am. Mus. Nat. Hist. 297, 1â370) monographic study of amphibian systematics, concluding that it is âa disasterâ and recommending that readers âsimply ignore this studyâ. Beyond the hyperbole, Wiens raised four general objections that he regarded as âfatal flawsâ: (1) the sampling design was insufficient for the generic changes made and taxonomic changes were made without including all type species; (2) the nuclear gene most commonly used in amphibian phylogenetics, RAG-1, was not included, nor were the morphological characters that had justified the older taxonomy; (3) the analytical method employed is questionable because equally weighted parsimony âassumes that all characters are evolving at equal ratesâ; and (4) the results were at times âclearly erroneousâ, as evidenced by the inferred non-monophyly of marsupial frogs. In this paper we respond to these criticisms. In brief: (1) the study of Frost et al. did not exist in a vacuum and we discussed our evidence and evidence previously obtained by others that documented the non-monophyletic taxa that we corrected. Beyond that, we agree that all type species should ideally be included, but inclusion of all potentially relevant type species is not feasible in a study of the magnitude of Frost et al. and we contend that this should not prevent progress in the formulation of phylogenetic hypotheses or their application outside of systematics. (2) Rhodopsin, a gene included by Frost et al. is the nuclear gene that is most commonly used in amphibian systematics, not RAG-1. Regardless, ignoring a study because of the absence of a single locus strikes us as unsound practice. With respect to previously hypothesized morphological synapomorphies, Frost et al. provided a lengthy review of the published evidence for all groups, and this was used to inform taxonomic decisions. We noted that confirming and reconciling all morphological transformation series published among previous studies needed to be done, and we included evidence from the only published data set at that time to explicitly code morphological characters (including a number of traditionally applied synapomorphies from adult morphology) across the bulk of the diversity of amphibians (Haas, 2003, Cladistics 19, 23â90). Moreover, the phylogenetic results of the Frost et al. study were largely consistent with previous morphological and molecular studies and where they differed, this was discussed with reference to the weight of evidence. (3) The claim that equally weighted parsimony assumes that all characters are evolving at equal rates has been shown to be false in both analytical and simulation studies. (4) The claimed âstrong supportâ for marsupial frog monophyly is questionable. Several studies have also found marsupial frogs to be non-monophyletic. Wiens et al. (2005, Syst. Biol. 54, 719â748) recovered marsupial frogs as monophyletic, but that result was strongly supported only by Bayesian clade confidence values (which are known to overestimate support) and bootstrap support in his parsimony analysis was <â50%. Further, in a more recent parsimony analysis of an expanded data set that included RAG-1 and the three traditional morphological synapomorphies of marsupial frogs, Wiens et al. (2006, Am. Nat. 168, 579â596) also found them to be non-monophyletic. Although we attempted to apply the rule of monophyly to the naming of taxonomic groups, our phylogenetic results are largely consistent with conventional views even if not with the taxonomy current at the time of our writing. Most of our taxonomic changes addressed examples of non-monophyly that had previously been known or suspected (e.g., the non-monophyly of traditional Hyperoliidae, Microhylidae, Hemiphractinae, Leptodactylidae, Phrynobatrachus , Ranidae, Rana , Bufo ; and the placement of Brachycephalus within â Eleutherodactylus â, and Lineatriton within â Pseudoeurycea â), and it is troubling that Wiens and others, as evidenced by recent publications, continue to perpetuate recognition of non-monophyletic taxonomic groups that so profoundly misrepresent what is known about amphibian phylogeny. © The Willi Hennig Society 2007.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74688/1/j.1096-0031.2007.00181.x.pd
Electroweak symmetry breaking in other terms
We analyse descriptions of electroweak symmetry breaking in terms of
ultralocal antisymmetric tensor fields and gauge-singlet geometric variables,
respectively; in particular, the Weinberg--Salam model and, ultimately,
dynamical electroweak symmetry breaking by technicolour theories with enhanced
symmetry groups. Our motivation is to unveil the manifestly gauge invariant
structure of the different realisations. We find, for example, parallels to
different types of torsion.Comment: 15p
Quaternion-Octonion Analyticity for Abelian and Non-Abelian Gauge Theories of Dyons
Einstein- Schroedinger (ES) non-symmetric theory has been extended to
accommodate the Abelian and non-Abelian gauge theories of dyons in terms of the
quaternion-octonion metric realization. Corresponding covariant derivatives for
complex, quaternion and octonion spaces in internal gauge groups are shown to
describe the consistent field equations and generalized Dirac equation of
dyons. It is also shown that quaternion and octonion representations extend the
so-called unified theory of gravitation and electromagnetism to the Yang-Mill's
fields leading to two SU(2) gauge theories of internal spaces due to the
presence of electric and magnetic charges on dyons
Physics with the KLOE-2 experiment at the upgraded DANE
Investigation at a --factory can shed light on several debated issues
in particle physics. We discuss: i) recent theoretical development and
experimental progress in kaon physics relevant for the Standard Model tests in
the flavor sector, ii) the sensitivity we can reach in probing CPT and Quantum
Mechanics from time evolution of entangled kaon states, iii) the interest for
improving on the present measurements of non-leptonic and radiative decays of
kaons and eta/eta mesons, iv) the contribution to understand the
nature of light scalar mesons, and v) the opportunity to search for narrow
di-lepton resonances suggested by recent models proposing a hidden dark-matter
sector. We also report on the physics in the continuum with the
measurements of (multi)hadronic cross sections and the study of gamma gamma
processes.Comment: 60 pages, 41 figures; added affiliation for one of the authors; added
reference to section
Around neoliberalism: Democracy threatened
This text seeks to reflect on the effect of neoliberalism on people's lives. How it manages to mutate and access new ways to capture democracies through social media and digital information, no longer through restrictions, but rather to encourage voluntary delivery of information that is available for human behavior analysis. These new ways of maintaining control of citizens and the environment have serious effects on the deterioration of the environment and people's health, but it rarely receives a sanction. In this sense, we are talking about a neoliberalicide, because the model remains more relevant than life and maintaining a balance with the environment. © 2021 Revista Notas Historicas y Geograficas.El presente texto busca reflexionar respecto
al efecto que tiene el neoliberalismo en la
vida de las personas. Como logra mutar y
acceder a nuevas formas de capturar las
democracias a través de las redes sociales y
la información digital, ya no a través de
restricciones, sino por el contrario, a
fomentar la entrega voluntaria de
informaciĂłn que queda disponible para
anĂĄlisis de comportamientos humanos. Estas
nuevas formas de mantener el control de los
ciudadanos y del ambiente tienen efectos
graves en el deterioro del ambiente y en la
salud de las personas, pero rara vez recibe
una sanciĂłn. En este sentido, hablamos de un
neoliberalicidio, pues el modelo sigue siendo
mĂĄs relevante que la vida y el mantener un
equilibrio con el entorno
Increased moral condemnation of accidental harm in institutionalized adolescents
Social deprivation, as faced by children in institutional rearing, involves socio-cognitive deficits that may persist into adolescence. In particular, two relevant domains which prove sensitive to pre-adult neurodevelopment are theory of mind (ToM) and moQ1Q1Revista Internacional - IndexadaA1S