Isospin Symmetry Breaking within the HLS Model: A Full (ρ,ω,ϕ\rho, \omega, \phi) Mixing Scheme

We study the way isospin symmetry violation can be generated within the Hidden Local Symmetry (HLS) Model. We show that isospin symmetry breaking effects on pseudoscalar mesons naturally induces correspondingly effects within the physics of vector mesons, through kaon loops. In this way, one recovers all features traditionally expected from \rho-\omg mixing and one finds support for the Orsay phase modelling of the e^+e^- \ra \pi^+ \pi^- amplitude. We then examine an effective procedure which generates mixing in the whole $\rho$, \omg, $\phi$ sector of the HLS Model. The corresponding model allows us to account for all two body decays of light mesons accessible to the HLS model in modulus and phase, leaving aside the \rho \ra \pi \pi and K^* \ra K \pi modes only, which raise a specific problem. Comparison with experimental data is performed and covers modulus and phase information; this represents 26 physics quantities successfully described with very good fit quality within a constrained model which accounts for SU(3) breaking, nonet symmetry breaking in the pseudoscalar sector and, now, isospin symmetry breaking.Comment: 38 pages, version published in Eur. Phys. J.

VMD, the WZW Lagrangian and ChPT: The Third Mixing Angle

We show that the Hidden Local Symmetry Model, supplemented with well-known procedures for breaking flavor SU(3) and nonet symmetry, provides all the information contained in the standard Chiral Perturbation Theory (ChPT) Lagrangian ${\cal L}^{(0)}+{\cal L}^{(1)}$. This allows to rely on radiative decays of light mesons ($VP\gamma$ and $P \gamma\gamma$) in order to extract some numerical information of relevance to ChPT: a value for $\Lambda_1=0.20 \pm 0.04$, a quark mass ratio of $\simeq 21.2 \pm 2.4$, and a negligible departure from the Gell-Mann--Okubo mass formula. The mixing angles are $\theta_8=-20.40^\circ \pm 0.96^\circ$ and $\theta_0=-0.05^\circ \pm 0.99^\circ$. We also give the values of all decay constants. It is shown that the common mixing pattern with one mixing angle $\theta_P$ is actually quite appropriate and algebraically related to the $\eta/\eta'$ mixing pattern presently preferred by the ChPT community. For instance the traditional $\theta_P$ is functionally related to the ChPT $\theta_8$ and fulfills $\theta_P \simeq \theta_8/2$. The vanishing of $\theta_0$, supported by all data on radiative decays, gives a novel relation between mixing angles and the violation of nonet symmetry in the pseudoscalar sector. Finally, it is shown that the interplay of nonet symmetry breaking through U(3) \ra SU(3)$\times$ U(1) satisfies all requirements of the physics of radiative decays without any need for additional glueballs.Comment: 31 pages, 1 figur

Decoherence in Phase Space

Much of the discussion of decoherence has been in terms of a particle moving in one dimension that is placed in an initial superposition state (a Schr\"{o}dinger "cat" state) corresponding to two widely separated wave packets. Decoherence refers to the destruction of the interference term in the quantum probability function. Here, we stress that a quantitative measure of decoherence depends not only on the specific system being studied but also on whether one is considering coordinate, momentum or phase space. We show that this is best illustrated by considering Wigner phase space where the measure is again different. Analytic results for the time development of the Wigner distribution function for a two-Gaussian Schrodinger "cat" state have been obtained in the high-temperature limit (where decoherence can occur even for negligible dissipation) which facilitates a simple demonstration of our remarks.Comment: in press in Laser Phys.13(2003

A small molecule that induces assembly of a four way DNA junction at low temperature

Small molecules that induce the formation of higher order DNA structures have potential therapeutic and nanotechnology applications. Screening of a click library has identified the first compound to induce the formation of a Holliday junction structure at room temperature without the need for a high temperature annealing step

Vector Meson Mixing and Charge Symmetry Violation

We discuss the consistency of the traditional vector meson dominance (VMD) model for photons coupling to matter, with the vanishing of vector meson-meson and meson-photon mixing self-energies at q^2=0. This vanishing of vector mixing has been demonstrated in the context of rho-omega mixing for a large class of effective theories. As a further constraint on such models, we here apply them to a study of photon-meson mixing and VMD. As an example we compare the predicted momentum dependence of one such model with a momentum-dependent version of VMD discussed by Sakurai in the 1960's. We find that it produces a result which is consistent with the traditional VMD phenomenology. We conclude that comparison with VMD phenomenology can provide a useful constraint on such models.Comment: 7 pages, uses epsfig.sty. Publication details added to title pag

Smc5/6 is required for repair at collapsed replication forks.

In eukaryotes, three pairs of structural-maintenance-of-chromosome (SMC) proteins are found in conserved multisubunit protein complexes required for chromosomal organization. Cohesin, the Smc1/3 complex, mediates sister chromatid cohesion while two condensin complexes containing Smc2/4 facilitate chromosome condensation. Smc5/6 scaffolds an essential complex required for homologous recombination repair. We have examined the response of smc6 mutants to the inhibition of DNA replication. We define homologous recombination-dependent and -independent functions for Smc6 during replication inhibition and provide evidence for a Rad60-independent function within S phase, in addition to a Rad60-dependent function following S phase. Both genetic and physical data show that when forks collapse (i.e., are not stabilized by the Cds1Chk2 checkpoint), Smc6 is required for the effective repair of resulting lesions but not for the recruitment of recombination proteins. We further demonstrate that when the Rad60-dependent, post-S-phase Smc6 function is compromised, the resulting recombination-dependent DNA intermediates that accumulate following release from replication arrest are not recognized by the G2/M checkpoint

Making it work: A study of Australian expatriate language and cultural strategies for the workplace in Japan

Australia has maintained a steady and strong business relationship with Japan for over three decades. In fact, Japan ranks first in terms of important export markets for Australia. As a result, it can be assumed that, on a micro-level, the possibility of more expatriates from Australia being stationed in Japan will increase to facilitate business communication and transactions between Australian and Japanese companies. With the creation of multinational workplaces, including Australians and Japanese working together in Japan, comes an increasing necessity for Australian expatriates to have linguistic and cultural competence. While this has been identified in intercultural communication research, the implementations of such findings related to Japanese language proficiency and how it benefits Australian-Japanese workplace communication is seemingly sporadic despite the investment into Japanese language education by Australia

Inositol phosphatase SHIP1 is a primary target of miR-155

MicroRNA-155 (miR-155) has emerged as a critical regulator of immune cell development, function, and disease. However, the mechanistic basis for its impact on the hematopoietic system remains largely unresolved. Because miRNAs function by repressing specific mRNAs through direct 3′UTR interactions, we have searched for targets of miR-155 implicated in the regulation of hematopoiesis. In the present study, we identify Src homology-2 domain-containing inositol 5-phosphatase 1 (SHIP1) as a direct target of miR-155, and, using gain and loss of function approaches, show that miR-155 represses SHIP1 through direct 3′UTR interactions that have been highly conserved throughout evolution. Repression of endogenous SHIP1 by miR-155 occurred following sustained over-expression of miR-155 in hematopoietic cells both in vitro and in vivo, and resulted in increased activation of the kinase Akt during the cellular response to LPS. Furthermore, SHIP1 was also repressed by physiologically regulated miR-155, which was observed in LPS-treated WT versus miR-155−/− primary macrophages. In mice, specific knockdown of SHIP1 in the hematopoietic system following retroviral delivery of a miR-155-formatted siRNA against SHIP1 resulted in a myeloproliferative disorder, with striking similarities to that observed in miR-155-expressing mice. Our study unveils a molecular link between miR-155 and SHIP1 and provides evidence that repression of SHIP1 is an important component of miR-155 biology

Note on the derivative of the hyperbolic cotangent

In a letter to Nature (Ford G W and O'Connell R F 1996 Nature 380 113) we presented a formula for the derivative of the hyperbolic cotangent that differs from the standard one in the literature by an additional term proportional to the Dirac delta function. Since our letter was necessarily brief, shortly after its appearance we prepared a more extensive unpublished note giving a detailed explanation of our argument. Since this note has been referenced in a recent article (Estrada R and Fulling S A 2002 J. Phys. A: Math. Gen. 35 3079) we think it appropriate that it now appear in print. We have made no alteration to the original note