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Search Results: 1 - 10 of 41 matches for " Ivon Kasonga "
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Prognostic of the New Nests of Seropositive Mothers Beneficiaries of the Prevention of Mother-Child Transmission in the City of Mbuji-Mayi/Drc  [PDF]
Jean Christophe Bukasa Tshilonda, Ivon Kasonga, Isaac Kalenda Ilunga, Moise Kanyiki Katala, Justin Tshibangu Kandala, Valentin Kabambi Bukasa, Ennock Mbuyi Kabeya, Nana Dikoma Misenga, Thérèse Kapenga Mitanta, Bertin Mpaka Mpaka, Mediatrice Kasheta Mabondo, Olivier Ejiba Nyongonyi, Paulin Kabamba Lupueka, Alain Ngoyi Kibambe, Alexis Ntambwe Mayombo, Emmanuel Mubala Mpetemba, Michel Kabamba Nzaji
Open Access Library Journal (OALib Journal) , 2019, DOI: 10.4236/oalib.1105267
Objective: The objective of this study is to evaluate the success of Moth-er-to-Child Transmission Prevention (PMTCT) is reducing the morbidity and mortality of newborns related to HIV/AIDS. Materials and Methods: This is a descriptive correlational study whose data collection is done in a transversal way from 01 to 30 June 2017 among HIV-positive women screened and we antiretroviral treatment in the health area targeted by this study. To collect this data, we used the semi-structured technical interview face-to-face using a questionnaire. Results: The results of the bivariate analysis revealed the HIV positive outcome in newborns of HIV-positive mothers is significantly related to the following factors (i.e,. p < 0.05): the parity of more than 5 children; lack of knowledge of some HIV infection pathways; lack of knowledge of some factors that promote the transmission of HIV from mother to child, such as: several infections in the mother; mixed feeding; lack of treatment of the mother; multiple pregnancies; non-monitoring of PMTCT activities; childbirth at home; mixed feeding and non-monitoring of PMTCT services with all pregnancies after-positive HIV diagnosis; lack of knowledge of the center offering the PMTCT service in service within its radius; poor monitoring of antiretroviral therapy and the effect of not HAVING applied to family planning method. Conclusion: The WHO advises inside this box to promote education, information and communication services for health that are ignored by the population using the available communication channels in the respective areas; apply mass communication to inform pregnant women about the existence of PMTCT services in health centers or hospitals.
Algebraically equipped posets
Raymundo Bautista,Ivon Dorado
Mathematics , 2015,
Abstract: We introduce partially ordered sets (posets) with an additional structure given by a collection of vector subspaces of an algebra $A$. We call them algebraically equipped posets. Some particular cases of these, are generalized equipped posets and $p$-equipped posets, for a prime number $p$. We study their categories of representations and establish equivalences with some module categories, categories of morphisms and a subcategory of representations of a differential tensor algebra. Through this, we obtain matrix representations and its corresponding matrix classification problem.
Evaluation of Screw Reinforcement on Bearing Performance of Wood Depending on Screw Position  [PDF]
Satoru Murakami, Akihisa Kitamori, Kiho Jung, Ivon B. Hassel, Kohei Komatsu
Open Journal of Civil Engineering (OJCE) , 2012, DOI: 10.4236/ojce.2012.23021
Abstract: In this study, the reinforcement of wood by screws for partial compression perpendicular to the grain was studied. For the estimation of stiffness and strength, the reinforcement effect of screws depending on their position under the loading plate was evaluated by taking into account the internal displacement distribution of the wood. The finite element analysis (FEA) was used to investigate the internal displacement distribution of the wood. Then an approximate function that can be applied to various internal displacement distributions under loading plate was proposed. From the shear resistance mechanism between the screw and wood by taking their relative displacement distribution into consideration, the equations to estimate the initial stiffness and yield strength of the bearing performance of the wood reinforced by screws were derived. Then partial compression test was carried out for wood reinforced by screws with setting screw thread at various positions. The values obtained by the equations corresponded with the tendency of the experimental results. It was found that the screw reinforcement is more effective when its thread is positioned as much as distant from the contact surface.
Spin Excitations in Half-Doped Manganites
Ivon R. Buitrago,C. I. Ventura
Physics , 2013, DOI: 10.1007/s10948-012-1431-6
Abstract: We investigate magnetic excitations in half-doped colossal magnetoresistance manganites. In particular, we focus on spin excitations in the CE phase originally proposed by Goodenough (Phys. Rev. 100, 564 (1955)). Using a localized spin model we calculated magnons for 3D-perovskite compounds such as La$_{1-x}$M$_x$MnO$_3$, where M=Ca,Sr,Ba, and for their 2D-laminar counterparts. We compared them with predictions for the spin excitations corresponding to other phases proposed. For the laminar half-doped manganite La$_{0.5}$Sr$_{1.5}$MnO$_4$, for which magnon measurements by inelastic neutron scattering exist, as well as an estimation of the magnetic couplings, our calculations agree well with the experimental data.
Magnetic excitations of perovskite rare-earth nickelates: RNiO$_3$
Ivon R. Buitrago,Cecilia I. Ventura
Physics , 2015, DOI: 10.1016/j.jmmm.2015.06.056
Abstract: The perovskite nickelates RNiO$_3$ (R: rare-earth) have been studied as potential multiferroic compounds. A certain degree of charge disproportionation in the Ni ions has been confirmed by high resolution synchrotron power diffraction: instead of the nominal Ni$^{3+}$ valence, they can have the mixed-valence state Ni$^{(3-\delta)+}$ and Ni$^{(3+\delta)+}$, though agreement has not been reached on the precise value of $\delta$ (e.g. for NdNiO$_3$, $\delta=0.0$ and $\delta=0.29$ were reported). Also, the magnetic ground state is not yet clear: collinear and non-collinear Ni-O magnetic structures have been proposed to explain neutron diffraction and soft X-ray resonant sccattering results in these compounds, and more recently a canted antiferromagnetic spin arrangement was proposed on the basis of magnetic susceptibility measurements. This scenario is reminiscent of the situation in the half-doped manganites. In order to gain insight into the ground state of these compounds, we studied the magnetic excitations of some of the different phases proposed, using a localized spin model for a simplified spin chain which could describe these compounds. We first analize the stability of the collinear, orthogonal, and intermediate phases in the classical case. We then explore the quantum ground state indirectly, calculating the spin excitations obtained for each phase, using the Holstein-Primakoff transformation and the linear spin-wave approximation. For the collinear and orthogonal ($\theta=\pi/2$) phases, we predict differences in the magnon spectrum which would allow to distinguish between them in future inelastic neutron scattering experiments.
In vitro effekte van eikosapenta n esuur en prostaglandien E3 op proliferasie, osteoklastvorming en beenresorpsie in RAW 264.7 muismakrofae
A.E. Kasonga,J.C.A. Boeyens,M. Coetzee
Suid-Afrikaanse Tydskrif vir Natuurwetenskap en Tegnologie , 2012, DOI: 10.4102/satnt.v31i1.290
Quantum magnons of the intermediate phase of half-doped manganite oxides
Ivon R. Buitrago,Cecilia I. Ventura,Luis O. Manuel
Physics , 2013, DOI: 10.1109/TMAG.2013.2261417
Abstract: At half doping, the ground state of three-dimensional manganite perovskite oxides like R$_{1-x}$Ca$_x$MnO$_3$, where R is a trivalent ion such as La, Pr, etc, is still unclear. Many experimental findings agree better with the combined magnetic, charge, and orbital order characteristic of the "intermediate phase", introduced by Efremov et al. in 2004 [Nature Mats. 3, 853]. This phase consists of spin dimers (thus incorporating aspects of the Zener polaron phase (ZP) proposed in 2002 by Daoud-Aladine et al. [Phys. Rev. Lett. 89, 097205]), though formed by a pair of parallel Mn spins of different magnitude, in principle (thereby allowing for a degree of Mn charge disproportionation: not necessarily as large as that of Mn$^{3+}$-Mn$^{4+}$ in Goodenough's original CE phase [Phys. Rev. 100, 564 (1955)]). In the intermediate phase, consecutive spin dimers localed along the planar zig-zag chains are oriented at a constant relative angle $\Phi$ between them. Varying Mn-charge disproportionation and $\Phi$, the intermediate phase should allow to continuously interpolate between the two limiting cases of the CE phase and the dimer phase denoted as "orthogonal intermediate $\pi/2-$phase". It is not easy to find a microscopic model able to describe the phenomenological intermediate phase adequately for the spin, charge, and orbital degrees of freedom simultaneously. Here, we study the quantum spin excitations of a planar model of interacting localized spins, which we found can stabilize the intermediate phase classically. We compare the quantum magnons of the intermediate phase with those of the CE and orthogonal $\pi/2$ phases, in the context of recent experimental results.
Third and Fourth Order Phase Transitions: Exact Solution for the Ising Model on the Cayley Tree
Borko D. Stosic,Tatijana Stosic,Ivon P. Fittipaldi
Physics , 2005,
Abstract: An exact analytical derivation is presented, showing that the Ising model on the Cayley tree exhibits a line of third order phase transition points, between temperatures $T_2=2k_B^{-1}J\ln ({\sqrt 2}+1) $ and $T_{BP}=k_B^{-1}J\ln (3)$, and a line of fourth order phase transitions between $T_{BP}$ and $\infty$, where $k_B$ is the Boltzmann constant, and $J$ is the nearest-neighbor interaction parameter.
Anomalous Behavior of the Zero Field Susceptibility of the Ising Model on the Cayley Tree
Tatijana Stosic,Borko D. Stosic,Ivon P. Fittipaldi
Physics , 2002, DOI: 10.1016/S0378-4371(02)01541-8
Abstract: It is found that the zero field susceptibility chi of the Ising model on the Cayley tree exhibits unusually weak divergence at the critical point Tc. The susceptibility amplitude is found to diverge at Tc proportionally to the tree generation level n, while the behavior of chi is otherwise analytic in the vicinity of Tc, with the critical exponent gamma=0.
Spin excitations of half-doped bilayer manganites: intermediate phase
Ivon R Buitrago,Cecilia I. Ventura,Luis O. Manuel
Physics , 2014,
Abstract: Few magnon measurements in half-doped manganites are available. Recently, the spin-wave spectrum of half-doped bilayer Pr(Ca0.9Sr0.1)2Mn2O7 was reported (Johnstone et al 2012 Phys.Rev.Lett.109 237202). The best fit included, using a localized spin model, corresponds to a ground state with a combined spin, charge and orbital ordering analogous to the CE phase proposed by Goodenough in 1955, though with a quite larger Mn-charge disproportionation. The latter contradicts previous experimental indications in half-doped manganites, pointing toward smaller Mn-disproportionations: in a range between the minimum value corresponding to the Zener-polaron or dimer phase (with all Mn-charges formally equal to 3.5+), and the maximum disproportionation found in Goodenough's CE phase (with Mn3+ and Mn4+). Such indications led to the intermediate phase proposal (Efremov et al 2004 Nat.Mats.3 853). Here, we analize the spin excitations of half-doped bilayer (and layered) manganites, calculating them in terms of a localized spin model suitable to describe the intermediate, CE and dimer phases. We discuss the effects of an extensive set of magnetic couplings, including all those introduced in previous fits. An improved description of the magnons reported for bilayer manganites is obtained assuming a generalized CE phase with Mn-disproportionation inside the expected range, by including next-nearest-neighbour magnetic coupling parameters between the planar Mn zig-zag chains.
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