The catalogue of OB associations in IC 1613

We present a catalogue of OB associations in IC 1613. Using an automatic and objective method (Battinelli's 1991 technique) 60 objects were found. The size distribution reveals a significant peak at about 60 parsecs if a distance modulus of 24.27 mag is assumed. Spatial distributions of the detected associations and H II regions are strongly correlated.Comment: 5 pages, 3 figures, A&A accepte

The influence of massive stars in the interstellar medium of IC 1613: the supernova remnant S8 and the nebula S3 associated with a WO star

We present a detailed kinematical analysis of two selected nebulae in the Local Group irregular galaxy IC 1613. The nebulae are: S8, the only known supernova remnant in this galaxy, and S3, a Wolf-Rayet nebula associated with the only WO star in this galaxy. For S8, we have obtained and analyzed its radial velocity field, where we found complex profiles which can be fitted by several velocity components. These profiles also show the presence of high velocity, low density gas. From this, we have obtained the expansion velocity, estimated the preshock density and calculated the basic kinematical parameters of this SNR. We suggest that in S8 we are seing a SNR partially hidden by dust. This suggestion comes from the fact that the SNR is located between two superbubbles where a ridge of obscured material unveils the existence of dust. Moreover, we show that this hypothesis prevails when energetic arguments are taken into account. In the case of S3, this nebula shows bipolar structure. By means of its kinematics, we have analyzed its two lobes, the ``waist'', as well as its relation with the nearest superbubbles. For the first time we are able to see closed the NW lobe, showing a clover leaf shape. This fact allows a better quantitative knowledge of the nebula as a whole. Furthermore, we found evidence of an expansion motion in the NW lobe. In the light of our results, we can express that these nebulae are the product of very massive stellar evolution. It is surprising the influence these stars still have in shaping their surrounding gas, and on the energy liberation towards the interstellar medium of this galaxy.Comment: Accepted for publication in the Astronomical Journal, July issue. 11 pages, 12 figures. High resolution figures can be found at http://www.inaoep.mx/~mago/PAPERS/AJ

Effects of physics beyond the standard model on the neutrino charge radius: an effective Lagrangian approach

In this work, we look for possible new physics effects on the electromagnetic charge and anapole form factors, $f_Q(q^2)$ and $f_A(q^2)$, for a massless Dirac neutrino, when these quantities are calculated in the context of an effective electroweak Yang-Mills theory, which induces the most general $SU_L(2)$--invariant Lorentz tensor structure of nonrenormalizable type for the $WW\gamma$ vertex. It is found that in this context, besides the standard model contribution, the additional contribution to $f_{Q}(q^2)$ and $f_{A}(q^2)$ ($f_{Q}^{O_W}(q^2)$ and $f_{A}^{O_W}(q^2)$, respectively) are gauge independent and finite functions of $q^2$ after adopting a renormalization scheme. These form factors, $f_{Q}^{O_W}(q^2)$ and $f_{A}^{O_W}(q^2)$, get contribution at the one loop level only from the proper neutrino electromagnetic vertex. Besides, the relation $f_{Q}^{eff}(q^2)=q^2f_{A}^{eff}(q^2)$ ($f_{Q}^{eff}(q^2)=f_{Q}^{SM}(q^2)+f_{Q}^{O_W}(q^2)$, $f_{A}^{eff}(q^2)=f_{A}^{SM}(q^2)+f_{A}^{O_W}(q^2)$) is still fulfilled and hence the relation $a_{\nu}^{eff} = ^{eff} /6$ ($a_{\nu}^{eff} = a_{\nu}^{SM}+ a_{\nu}^{O_W}$, $^{eff} = ^{SM}+< r^2_{\nu} > ^{O_W}$)is gotten, just as in the SM. Using the experimental constraint on the anomalous $WW\gamma$ vertex, a value for the additional contribution to the charge radius of |^{O_W}| \lsim 10^{-34} cm^2 is obtained, which is one order of magnitude lower than the SM value.Comment: 9 pages, 3 figure

Supernova Remnants in the Magellanic Clouds III: An X-ray Atlas of LMC Supernova Remnants

We have used archival ROSAT data to present X-ray images of thirty-one supernova remnants (SNRs) in the Large Magellanic Cloud (LMC). We have classified these remnants according to their X-ray morphologies, into the categories of Shell-Type, Diffuse Face, Centrally Brightened, Point-Source Dominated, and Irregular. We suggest possible causes of the X-ray emission for each category, and for individual features of some of the SNRs.Comment: 27 pages, 6 figures (9 figure files). To appear in the Supplement Series of the Astrophysical Journal, August 1999 Vol. 123 #

Analysis of the quark sector in the 2HDM-III with a four-zero Yukawa texture using the most recent data on the CKM matrix

In this letter we analyse, in the context of the general 2-Higgs Doublet Model, the structure of the Yukawa matrices, $\widetilde{ \bf Y}_{ _{1,2} }^{q}$, by assuming a four-zero texture ansatz for their definition. In this framework, we obtain compact expressions for $\widetilde{ \bf Y}_{ _{1,2} }^{q}$, which are reduced to the Cheng and Sher ansatz with the difference that they are obtained naturally as a direct consequence of the invariants of the fermion mass matrices. Furthermore, in order to avoid large flavour violating effects coming from charged Higgs exchange, we consider the main flavour constraints on the off-diagonal terms of Yukawa texture {{$\left( \widetilde{\chi}_{j}^q \right)_{kl}$}} ($k\neq l$). We perform a $\chi^2$-fit based on current experimental data on the quark masses and the Cabibbo-Kobayashi-Maskawa mixing matrix ${ \bf V}_{\rm CKM }$. Hence, we obtain the allowed ranges for the parameters $\widetilde{ \bf Y}_{ _{1,2} }^{q}$ at 1$\sigma$ for several values of $\tan \beta$. The results are in complete agreement with the bounds obtained taking into account constraints on Flavour Changing Neutral Currents reported in the literature.Comment: 12 pages, 1 figure. Version accepted in Phys. Lett.

Supporting Nutrition Sensitive Agriculture through neglected and underutilized species: Operational framework

This joint Bioversity-IFAD publication was developed to guide IFAD and other agencies’ efforts in leveraging neglected and underutilized species (NUS) in support of Nutrition Sensitive Agriculture. It presents a holistic value chain approach for the use enhancement of these local resources in project design and implementation in order to attain more resilient production and food systems. It also highlights ways by which their better use can contribute towards the social and economic empowerment of marginalized groups, including women an Indigenous Peoples, who play an essential role in safeguarding their genetic diversity and associated traditional knowledge

Soutenir une agriculture axée sur la nutrition grâce aux espèces négligées et sous-utilisées: Cadre opérationnel.

This joint Bioversity-IFAD publication was developed to guide IFAD and other agencies’ efforts in leveraging neglected and underutilized species (NUS) in support of Nutrition Sensitive Agriculture. It presents a holistic value chain approach for the use enhancement of these local resources in project design and implementation in order to attain more resilient production and food systems. It also highlights ways by which their better use can contribute towards the social and economic empowerment of marginalized groups, including women an Indigenous Peoples, who play an essential role in safeguarding their genetic diversity and associated traditional knowledge