Decuplet baryon magnetic moments in a QCD-based quark model beyond quenched approximation

We study the decuplet baryon magnetic moments in a QCD-based quark model beyond quenched approximation. Our approach for unquenching the theory is based on the heavy baryon perturbation theory in which the axial couplings for baryon - meson and the meson-meson-photon couplings from the chiral perturbation theory are used together with the QM moment couplings. It also involves the introduction of a form factor characterizing the structure of baryons considered as composite particles. Using the parameters obtained from fitting the octet baryon magnetic moments, we predict the decuplet baryon magnetic moments. The $\Omega^-$ magnetic moment is found to be in good agreement with experiment: $\mu_{\Omega^-}$ is predicted to be $-1.97 \mu_N$ compared to the experimental result of ($-$2.02 $\pm$ 0.05) $\mu_N$.Comment: 19 pages, 2 figure

Baryon Magnetic Moments in Relativistic Quark Models

It is shown that the phenomenological description of the baryon magnetic moments in the quark model carries over to the Poincar\'e covariant extension of the model. This applies to all the three common forms of relativistic kinematics with structureless constituent currents, which are covariant under the corresponding kinematic subgroups. In instant and front form kinematics the calculated magnetic moments depend strongly on the constituent masses, while in point form kinematics the magnetic moments are fairly insensitive to both the quark masses and the wave function model. The baryon charge radii and magnetic moments are determined in the different forms of kinematics for the light-flavor, strange and charm hyperons. The wave function model is determined by a fit to the electromagnetic form factor of the proton.Comment: Six references and one paragraph adde

Effective field theory and the quark model

We analyze the connections between the quark model (QM) and the description of hadrons in the low-momentum limit of heavy-baryon effective field theory in QCD. By using a three-flavor-index representation for the effective baryon fields, we show that the ``nonrelativistic'' constituent QM for baryon masses and moments is completely equivalent through O(m_s) to a parametrization of the relativistic field theory in a general spin--flavor basis. The flavor and spin variables can be identified with those of effective valence quarks. Conversely, the spin-flavor description clarifies the structure and dynamical interpretation of the chiral expansion in effective field theory, and provides a direct connection between the field theory and the semirelativistic models for hadrons used in successful dynamical calculations. This allows dynamical information to be incorporated directly into the chiral expansion. We find, for example, that the striking success of the additive QM for baryon magnetic moments is a consequence of the relative smallness of the non-additive spin-dependent corrections.Comment: 25 pages, revtex, no figure

Contribution of the cyclic nucleotide gated channel subunit, CNG-3, to olfactory plasticity in Caenorhabditis elegans.

In Caenorhabditis elegans, the AWC neurons are thought to deploy a cGMP signaling cascade in the detection of and response to AWC sensed odors. Prolonged exposure to an AWC sensed odor in the absence of food leads to reversible decreases in the animal's attraction to that odor. This adaptation exhibits two stages referred to as short-term and long-term adaptation. Previously, the protein kinase G (PKG), EGL-4/PKG-1, was shown necessary for both stages of adaptation and phosphorylation of its target, the beta-type cyclic nucleotide gated (CNG) channel subunit, TAX-2, was implicated in the short term stage. Here we uncover a novel role for the CNG channel subunit, CNG-3, in short term adaptation. We demonstrate that CNG-3 is required in the AWC for adaptation to short (thirty minute) exposures of odor, and contains a candidate PKG phosphorylation site required to tune odor sensitivity. We also provide in vivo data suggesting that CNG-3 forms a complex with both TAX-2 and TAX-4 CNG channel subunits in AWC. Finally, we examine the physiology of different CNG channel subunit combinations

Analysis of dynamical corrections to baryon magnetic moments

We present and analyze QCD corrections to the baryon magnetic moments in terms of the one-, two-, and three-body operators which appear in the effective field theory developed in our recent papers. The main corrections are extended Thomas-type corrections associated with the confining interactions in the baryon. We investigate the contributions of low-lying angular excitations to the moments quantitatively and show that they are completely negligible. When the QCD corrections are combined with the non-quark model contributions of the meson loops, we obtain a model which describes the moments within a mean deviation of 0.04 $\mu_N$. The nontrivial interplay of the two types of corrections to the quark-model moments is analyzed in detail, and explains why the quark model is so successful. In the course of these calculations, we parametrize the general spin structure of the $j={1/2}^+$ baryon wave functions in a form which clearly displays the symmetry properties and the internal angular momentum content of the wave functions, and allows us to use spin-trace methods to calculate the many spin matrix elements which appear in the expressions for the moments. This representation may be useful elsewhere.Comment: 32 pages, 3 figures, submitted to Phys. Rev.

Eliciting a predatory response in the eastern corn snake (Pantherophis guttatus) using live and inanimate sensory stimuli: implications for managing invasive populations

North America's Eastern corn snake (Pantherophis guttatus) has been introduced to several islands throughout the Caribbean and Australasia where it poses a significant threat to native wildlife. Invasive snake control programs often involve trapping with live bait, a practice that, as well as being costly and labour intensive, raises welfare and ethical concerns. This study assessed corn snake response to live and inanimate sensory stimuli in an attempt to inform possible future trapping of the species and the development of alternative trap lures. We exposed nine individuals to sensory cues in the form of odour, visual, vibration and combined stimuli and measured the response (rate of tongue-flick [RTF]). RTF was significantly higher in odour and combined cues treatments, and there was no significant difference in RTF between live and inanimate cues during odour treatments. Our findings suggest chemical cues are of primary importance in initiating predation and that an inanimate odour stimulus, absent of simultaneous visual and vibratory cues, is a potential low-cost alternative trap lure for the control of invasive corn snake populations

Variation in the distribution and properties of Circumpolar Deep Water in the eastern Amundsen Sea, on seasonal timescales, using seal‐borne tags

In the Amundsen Sea, warm saline Circumpolar Deep Water (CDW) crosses the continental shelf toward the vulnerable West Antarctic ice shelves, contributing to their basal melting. Due to lack of observations, little is known about the spatial and temporal variability of CDW, particularly seasonally. A new dataset of 6704 seal‐tag temperature and salinity profiles in the easternmost trough between February and December 2014 reveals a CDW layer on average 49 db thicker in late winter (August to October) than in late summer (February to April), the reverse seasonality of that seen at moorings in the western trough. This layer contains more heat in winter, but on the 27.76 kg/m3 density surface CDW is 0.32° C warmer in summer than winter, across the northeastern Amundsen sea, which may indicate wintertime shoaling offshelf changes CDW properties onshelf. In Pine Island Bay these seasonal changes on density surfaces are reduced, likely by gyre circulation

Going to the exclusive show : exhibition strategies and moviegoing memories of Disneys animated feature films in Ghent (1937-1982)

This is a case study of the exploitation and experience of Disney's animated feature films from the 1930s to the 1980s in Ghent (Belgium). It is a historical study of programming practices and financial strategies which constructed childhood memories on watching Disney. The study is a contribution to a historical understanding of the implications of global distribution of film as cultural products and the counter pull of localism. Using a multi-method approach, the argument is made that the scarce screenings were strategically programmed to uplift the moviegoing experience into something out of the ordinary in everyday life. Programming and revenue data characterize the screenings as exclusive and generating high intakes. Consequently, the remembered screenings did not exhale an easy accessible social status nor an image of pervasiveness of popular childhood film, contradictory to conventional accounts of Disney's ubiquity in popular culture