Crystallographic orientation dependence of ferroelectric domain walls in antiferroelectric lead zirconate thin films

Coulibaly Mamadou D.,Borderon Caroline,Renoud Raphaël,Gundel Hartmut W. 한국물리학회 2022 Current Applied Physics Vol.39 No.-

Domains of antiferroelectric PbZrO3 have been studied. The (111) PbZrO3 has lower field transitions due to the reduction of the angle between the ferroelectric polar axis and the applied electric field. The study of the permittivity reveals also that the (111) PbZrO3 has a higher correlation of dipoles (|Shf| = 0.007) due to the energy gain associated with their orientation. Therefore, the (111) crystallographic orientation is a better choice for obtaining easily switching domain. The dielectric response of the domain walls in the (100) and (111) PbZrO3 are identical because they have the same environment (same grain size and similar defects) and interact in the same way. Only the domain wall density is higher in the (111) PbZrO3 due to its lower crystallographic orientation factor. Different crystallographic directions have more obstacles due to the inhomogeneity of the crystallization and consequently has more nucleation site for domain walls.

Cocoa Production Output Response to Smallholder Price Speculation: Case Study of Cote d’Ivoire and Nigeria

Coulibaly Kigbajah Salifou,Cao Erbao,Amadou Maiga Ousseini,T. Metuge Mekongcho 한국국제경제학회 2019 International Economic Journal Vol.33 No.2

The paper attempts to analyze the variation in cocoa output response to international price fluctuations in two major cocoa producing countries: Cote d’Ivoire and Nigeria. The study employs a Nerlovian price expectation technique as in Ogundari (2015), and a Panel VAR model to empirically estimate changes in cocoa output using time series and an unbalanced panel dataset covering a period from 1967 to 2009. The findings indicate and in accordance with economic theory of demand and supply, that cocoa output is an inverse function of the expected prices of competing agricultural commodities like green coffee. When there is an expected price increase of cocoa, cocoa output rises. Simultaneously, if the anticipated price of coffee rises, through a cocoa–coffee substitution mechanism, smallholder farmers shift their focus to coffee production leading to a fall in cocoa output. A Granger causality test was utilized to investigate causality between cocoa output, and cocoa and coffee prices. In the case of Cote d’Ivoire, while there is only a correlation between cocoa output and price, in the case of Nigeria there was none. In addition, the study shows no unidirectional or bidirectional causality between the intervening variables and cocoa output.

Assessment of Radiological Hazards in Some Foods Products Consumed by the Malian Population Using Gamma Spectrometry

Coulibaly Adama,Kpeglo David O.,Darko Emmanuel O. 대한방사선방어학회 2023 방사선방어학회지 Vol.48 No.2

Background : Food consumption is one of the most important routes for radionuclide intake for the public ; therefore , there is the need to have a comprehensive understanding of the amount of radioactivity in food products . Consumption of radionuclide-contaminated food could in- crease potential health risks associated with exposure to radiation such as cancers . The present study aims to determine radioactivity levels in some food products (milk , rice , sugar, and wheat flour) consumed in Mali and to evaluate the radiological effect on the public health from these radionuclides . Materials and Methods : The health impact due to ingestion of radionuclides from these foods was evaluated by the determination of activity concentration of radionuclides 238U, 232Th, 40K , and 137 Cs using gamma spectrometry system with high-purity germanium detector and radiological hazards index in 16 samples collected in some markets , mall , and shops of Bamako-Mali . JRPR Results and Discussion : The average activity concentrations were 9 . 8 ± 0 . 6 Bq/kg for 238U, 8.7± 0 . 5 Bq/kg for 232Th , 162 . 9 ± 7 . 9 Bq/kg for 40K , and 0 . 0035 ± 0 . 0005 Bq/kg for 137Cs . The mean values of radiological hazard parameters such as annual committed effective dose , internal haz- ard index , and risk assessment from this work were within the dose criteria limits given by in- ternational organizations (International Commission on Radiological Protection and United Nations Scientific Committee on the Effects of Atomic Radiation) and national standards . Conclusion : The results show low public exposure to radioactivity and associated radiological impact on public health . Nevertheless , this study stipulates vital data for future research and regulatory authorities in Mali .

Evaluating the Trade Effect of Developing Regional Trade Agreements: a Semi-parametric Approach

( Souleymane Coulibaly ) 세종대학교 경제통합연구소 (구 세종대학교 국제경제연구소) 2009 Journal of Economic Integration Vol.24 No.4

Many recent papers have pointed to ambiguous trade effects of developing regional trade agreements, calling for a reassessment of their economic merits. This paper focuses on 22 RTAs involving mostly developing countries and covering all the continents and use trade flows over the period 1962-2006. It proposes a two-step estimation approach to assess their trade impact: first estimate a gravity equation excluding the RTA variables, and then use the trade residuals estimated to run a kernel regression for each of the RTAs. This approach allows capturing the non-monotonic trade effects of the RTAs over time while imposing minimal structure on the model, and is flexible enough to be extended to any new RTA. As existing RTAs are deepened and new ones are being negotiated, ensuring that trade creation dominates trade diversion will be essential, particularly in the post-crisis world where resources will be limited for all countries.

Agglomeration and Specialization Patterns when Firms and Workers are Footloose

( Souleymane Coulibaly ) 세종대학교 경제통합연구소 2008 Journal of Economic Integration Vol.23 No.2

In new economic geography models, geographic concentration cant arise because of workers mobility or vertical linkages between firms. We examine a setup that combines those two approaches in conjunction with local congestion costs. We find that, as trade costs are lowered, the geographic concentration of total activity (agglomeration) follows an inverse u-shaped evolution, while the degree of specialization of regions increases. These results shed light on regional development within a country as integration proceeds: when trade costs are hight, firms evenly spread between the regions to supply local demand at low costs, hence diversified regions; at intermediate trade costs, we have coexistence of a diversified core and a specialized periphery and at low trade costs, each industry clusters in one region to fully exploit returns to scale externalities. US city centers and non-metropolitan areas during the period 1850-1990 depict such specialization and agglomeration patterns. These results show that a country`s effort to miprove accessibility across its porfolio of places can favor a win-win regional allocation of firms based on each location`s competitive advantage.

Antioxidant and Anti-Inflammatory Effects of Scoparia dulcis L.

Ahmed Y. Coulibaly,Martin Kiendrebeogo,Patrick G. Kehoe,Pierre A.E.D. Sombie,Charles E. Lamien,Jeanne F. Millogo,Odile G. Nacoulma 한국식품영양과학회 2011 Journal of medicinal food Vol.14 No.12

Different extracts were obtained from Scoparia dulcis L. (Scrophulariaceae) by successive extraction with hexane, chloroform, and methanol. These extracts exhibited significant antioxidant capacity in various antioxidant models mediated (xantine oxidase and lipoxygenase) or not mediated (2,2-diphenyl-picrylhydrazyl, ferric-reducing antioxidant power,β-carotene bleaching, lipid peroxidation) by enzymes. The antioxidant activity of the extracts was related to their phytochemical composition in terms of polyphenol and carotenoid contents. The chloroform extract was richest in phytochemicals and had the highest antioxidant activity in the different antioxidant systems. All the extracts exhibited less than 50% inhibition on xanthine oxidase but more than 50% inhibition on lipid peroxidation and lipoxygenase. The extracts strongly inhibited lipid peroxidation mediated by lipoxygenase.

Quenching for discretization of a nonlinear diffusion equation with singular boundary flux

NGuessan Koffi,Anoh Assiedou Rodrigue,Coulibaly Adama,Toure Kidjegbo Augustin 원광대학교 기초자연과학연구소 2022 ANNALS OF FUZZY MATHEMATICS AND INFORMATICS Vol.23 No.1

In this paper, we study the discrete approximation for the following nonlinear diffusion equation with nonlinear source and singular boundary flux $$\\ \left\{% \begin{array}{ll} \hbox{$\dfrac{\partial A(u)}{\partial t}=u_{xx} + (1-u)^{-\alpha}, \quad 0<x<1,\; t>0$,} \\ \hbox{$u_{x}(0,t)= 0, \quad u_{x}(1,t)=-B(u(1,t)),\quad t>0$,} \\ \hbox{$u(x,0)=u_{0}(x),\quad 0\leq x \leq 1$,} \\ \end{array}% \right. $$ with $ \alpha > 0. $ We find some conditions under which the solution of a discrete form of above problem quenches in a finite time and estimate its discrete quenching time. We also establish the convergence of the discrete quenching time to the theoretical one when the mesh size tends to zero. Finally, we give some numerical experiments for a best illustration of our analysis.

Numerical approximation of the quenching time for a non-Newtonian filtration equation with singular boundary flux

Camara Gninlfan Modeste,N’Guessan Koffi,Coulibaly Adama,Toure Kidjegbo Augustin 원광대학교 기초자연과학연구소 2021 ANNALS OF FUZZY MATHEMATICS AND INFORMATICS Vol.22 No.3

This paper concerns the study of the numerical approximation for the following initial-boundary value problem .$$\left\{% \begin{array}{ll} \hbox{$u_t=\left( \vert u_{x}\vert^{p-2}u_{x}\right)_{x} + \left( 1-u\right)^{-h} ,\quad 0<x<1,\; t>0$,} \\ \hbox{$u_{x}(0,t)=0, \quad u_{x}(1,t)= - u^{-q}(1,t),\quad t>0$,} \\ \hbox{$u(x,0)=u_{0}(x) > 0,\quad 0\leq x \leq 1$,} \\ \end{array}% \right. $$ where $p\geq 2$, $h>0$, $q>0$. $u_{0}: [0,1] \rightarrow (0,1)$ and satisfies compatiblity conditions. We find some conditions under which the solution of a discrete form of above problem quenches in a finite time and estimate its discrete quenching time. We also establish the convergence of the discrete quenching time to the theoretical one when the mesh size tends to zero. Finally, we give some numerical experiments for a best illustration of our analysis.

Protection of a Multicast Connection Request in an Elastic Optical Network Using Shared Protection

BODJRE, Aka Hugues Felix,ADEPO, Joel,COULIBALY, Adama,BABRI, Michel International Journal of Computer ScienceNetwork S 2021 International journal of computer science and netw Vol.21 No.1

Elastic Optical Networks (EONs) allow to solve the high demand for bandwidth due to the increase in the number of internet users and the explosion of multicast applications. To support multicast applications, network operator computes a tree-shaped path, which is a set of optical channels. Generally, the demand for bandwidth on an optical channel is enormous so that, if there is a single fiber failure, it could cause a serious interruption in data transmission and a huge loss of data. To avoid serious interruption in data transmission, the tree-shaped path of a multicast connection may be protected. Several works have been proposed methods to do this. But these works may cause the duplication of some resources after recovery due to a link failure. Therefore, this duplication can lead to inefficient use of network resources. Our work consists to propose a method of protection that eliminates the link that causes duplication so that, the final backup path structure after link failure is a tree. Evaluations and analyses have shown that our method uses less backup resources than methods for protection of a multicast connection.

Serotype Distribution and Virulence Profile of Salmonella enterica Serovars Isolated from Food Animals and Humans in Lagos Nigeria

Abraham, Ajayi,Stella, Smith,Ibidunni, Bode-Sojobi,Coulibaly, Kalpy Julien,Funbi, Jolaiya Tolulope,Isaac, Adeleye Adeyemi The Korean Society for Microbiology and Biotechnol 2019 한국미생물·생명공학회지 Vol.47 No.2

Distribution of Salmonella enterica serovars and their associated virulence determinants is wide-spread among food animals, which are continuously implicated in periodic salmonellosis outbreaks globally. The aim of this study was to determine and evaluate the diversity of five Salmonella serovar virulence genes (invA, pefA, cdtB, spvC and iroN) isolated from food animals and humans. Using standard microbiological techniques, Salmonella spp. were isolated from the feces of humans and three major food animals. Virulence determinants of the isolates were assayed using PCR. Clonal relatedness of the dominant serovar was determined via pulsed-field gel electrophoresis (PFGE) using the restriction enzyme, Xbal. Seventy one Salmonella spp. were isolated and serotyped into 44 serovars. Non-typhoidal Salmonella (NTS; 68) accounted for majority (95.8%) of the Salmonella serovars. Isolates from chicken (34) accounted for 47.9% of all isolates, out of which S. Budapest (14) was predominant (34.8%). However, the dominant S. Budapest serovars showed no genetic relatedness. The invA gene located on SPI-1 was detected in all isolates. Furthermore, 94% of the isolates from sheep harbored the spvC genes. The iroN gene was present in 50%, 100%, 88%, and 91% of isolates from human, chicken, sheep, and cattle, respectively. The pefA gene was detected in 18 isolates from chicken and a single isolate from sheep. Notably, having diverse Salmonella serovars containing plasmid encoded virulence genes circulating the food chain is of public health significance; hence, surveillance is required.