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.

어느 장님의 별들

Camara, D. Joao Da,최진화 한국외국어대학 학도호국단 1977 외대 Vol.12 No.1

Block-Based Scheme for Database Integrity Verification

Lancine Camara,Junyi Li,Renfa Li,Faustin Kagorora,Damien Hanyurwimfura 보안공학연구지원센터 2014 International Journal of Security and Its Applicat Vol.8 No.6

Databases play an important role today in every modern organization, verifying their integrity is needed. Watermarking can be used to protect the integrity of database. In this paper, we present a secure fragile embedding watermark technique to verify the authenticity of an outsourced numeric relational database. Our technique treats the watermark embedding as an optimization problem by securely inserting a single watermark bit in individual database partition and the optimal threshold is computed for watermark detection. The approach partitions the database in different groups of square matrix and modifies the database while preserving the field values usability constraints. The database group determinant value is used to compute the position of field to be marked. Furthermore, we evaluated our scheme on a real case study and results show its effectiveness. The proposed scheme can detect and localize the malicious modifications made to the database. The proposed technique is highly resilient to common attacks and it overcomes some limitations of previous approaches on fragile watermarking.

Measuring the Environment for Physical Activity in Early Childhood: A Narrative and Systematic Literature Review

Fabiano Camara,Stephen Berg,Brent Bradford,Sarah Hutchinson,Amanda Sardeli The Pacific Early Childhood Education Research Ass 2022 Asia-Pacific journal of research in early childhoo Vol.16 No.2

The aim of this study was to systematically review the protocols to assess the built environment in the context of early childhood and physical activity. Three databases were systematically searched for studies that examined associations between the built environment and preschoolers’ physical activity levels. A total of 27 studies were included in the analysis. Results show a clear distinction between approaches administered in the neighborhoods and childcare domains. Although Geographic Information Systems are employed in most studies in the neighborhood domain and have been understood as an objective approach, findings have indicated a lack of specificity regarding early childhood environmental variables, which can compromise protocols content validity. Further, although self-perceived approaches were found in only three studies, analysis of instrument content validity and cross-cultural adaptation also showed limited validation evidence. In the childcare context, the micro-scale built environment is a strong trend in customization of measurement protocols in early childhood. However, present findings have indicated the necessity for enhancements to validation procedures, particularly regarding internal consistency and content validity to develop needed customization. Therefore, future research should utilize more rigorous validation techniques to address the micro-scale built environment within the context of early childhood physical activity levels.

Study on the Improvement of Silver Recovery Efficiency by High Speed Rotation

A. Da Camara,이수완,박영서 한국표면공학회 2004 한국표면공학회 학술발표회 초록집 Vol.2004 No.-

A recovery system for silver in the plating rinse waters using electrowinning process was developed. The target of this work was checking the system characteristics and recovery capacity, as well as determining the best combination of equipment parameters that allows a good silver recovery efficiency. The equipment function parameters are current (0-30A), voltage (0-10V), rotation velocity (0-76rpm) and time (0-60min). Tests were carried out using a combination of these parameters and adding different amounts of conductivity salt (10% NaOH). The recovery percentage obtained range between 24.4% and 99.8%. The best efficiency was found using 30A, 40rpm, 60min and 3㎖/ℓ addition of conductivity salt.

Sunlight Incidence, Vitamin D Deficiency, and Alzheimer's Disease

Alice Barros Camara,Iara Dantas de Souza,Rodrigo Juliani Siqueira Dalmolin 한국식품영양과학회 2018 Journal of medicinal food Vol.21 No.9

Vitamin D (VD) deficiency is a growing problem, affecting a significant portion of the population in many countries. VD deficiency may be related to several diseases, including Alzheimer's disease (AD). This study aimed to review the relationship between VD deficiency and AD. We describe the proteins involved in AD pathogenesis and how those proteins can be influenced by VD deficiency. We also investigated a relationship between AD death rate and solar radiation and we found an increased AD death rate in countries with low sunlight. It was also observed that amyloid precursor protein, ryanodine receptor, mammalian target of rapamycin complex 1, and receptor for advanced glycation end products are associated with a worse prognosis in AD. While the Klotho protein, phosphatase and tensin homologue, and VD receptor are associated with a better prognosis in the disease. The literature suggests that decline in VD concentrations may be involved in the establishment and progression of AD. According to sunlight data, we can conclude that countries with low average sunlight have high AD death rate.

Hydrogenase Enzymes and Their Synthetic Models: The Role of Metal Hydrides

Schilter, David,Camara, James M.,Huynh, Mioy T.,Hammes-Schiffer, Sharon,Rauchfuss, Thomas B. American Chemical Society 2016 Chemical reviews Vol.116 No.15

<P>Hydrogenase enzymes efficiently process H-2 and protons at organometallic FeFe, NiFe, or Fe active sites. Synthetic modeling of the many H(2)ase states has provided insight into H(2)ase structure and mechanism, as well as afforded catalysts for the H-2 energy vector. Particularly important are hydride-bearing states, with synthetic hydride analogues now known for each hydrogenase class. These hydrides are typically prepared by protonation of low-valent cores. Examples of FeFe and NiFe hydrides derived from H-2 have also been prepared. Such chemistry is more developed than mimicry of the redox-inactive monoFe enzyme, although functional models of the latter are now emerging. Advances in physical and theoretical characterization of H(2)ase enzymes and synthetic models have proven key to the study of hydrides in particular, and will guide modeling efforts toward more robust and active species optimized for practical applications.</P>

The synergistic effects of five essential oils and eight chiral compounds on deltamethrin-piperonyl butoxide insecticide against Sitophilus zeamais (Coleoptera: Curculionidae)

Fouad Hany A.,da Camara Claudio A.G.,de Moraes Marcilio M.,de Melo João P.R. 한국응용곤충학회 2023 Journal of Asia-Pacific Entomology Vol.26 No.2

Sitophilus zeamais is a major cause of damage to corn and its preventive control is performed with DeltamethrinPiperonyl Butoxide (deltamethrin-PBO). However, due to the intensive use of conventional insecticides, the population of S. zeamais has developed resistance to nearly all classes of insecticides. In order to establish new control practices through the reduction of the use of conventional insecticides for management of S. zeamais, the present study was to evaluate the insecticidal activities and synergistic interaction between five essential oils, as well as six chiral constituents with deltamethrin-PBO used in the preventive control of S. zeamais. The chemical analysis revealed a high percentage of monoterpenes in the oils investigated. Limonene was the major compo nent found in the oils from Citrus aurantifolia and C. reticulata. Citronellal, terpinen-4-ol and menthol were the major constituents in the oils from Eucalyptus citriodora, Melaleuca alternifolia and Mentha piperita, respectively. Oil from M. alternifolia exhibited greater toxicity. Among chiral constituents, (R)-(+)-Limonene, (1R,5R)-(+)-α-pinene and (1S,5S)-(-)-α-pinene were the most toxic against the pest. Binary mixtures prepared with synthetic insecticide and oils exhibited two synergistic interactions. Mixtures prepared with deltamethrin-PBO and (R)-(+)-limonene showed one synergistic interaction. These results are promising, particularly the Citrus oils and its main constituent, (R)-(+)-limonene, which increased the mortality of S. zeamais by 56.41; 43.58 and 35.89 %, respectively. The present findings suggest that the impacts on the environment and human health with the indiscriminate use of deltamethrin-PBO can be minimized with the preparation of a formulation of this insecticide combined with Citrus oils.

Spirulina sp. biomass dried/disrupted by different methods and their application in biofilms production

Ana P. Q. Larrosa,Alisson S. Camara,Jaqueline M. Moura,Luiz A. A. Pinto 한국식품과학회 2018 Food Science and Biotechnology Vol.27 No.6

Arthrospira Spirulina biomass is a source of intracellular compounds with great commercial interest, such as phycocyanin and phenolic compounds. In this work, different cell disruption methods of the microalgae biomass dried in spouted bed and in conventional tray were performed, aiming lead to the better extraction yields of these compounds. The samples of both drying techniques with the most suitable cell disruption were used to biofilms production. FTIR, DSC, and SEM for all samples were performed. The samples dried in spouted bed with cell disruption by milling and by microwave showed the best results for the powder products, with phycocyanin contents of 75.0 and 85.4 mg g-1, and total phenolic compounds of 41.6 and 41.9 mg g-1, respectively. However, the tray drying/milling produced the biofilms with the best characteristics (tensile strength of 3.69 MPa and water vapor permeability of 1.67 9 10-11 g m s-1 m-2 Pa-1) and the highest thermal stability.

Assessment of Effects of a Cordia salicifolia Extract on the Radiolabeling of Blood Constituents and on the Morphology of Red Blood Cells

Jacques Natan Grinapel Frydman,Vanessa Camara Rocha,Monica Oliveira Benarroz,Gabrielle Souza Rocha,Márcia Oliveira Pereira,Adenilson de Souza da Fonseca,Mario Bernardo-Filho 한국식품영양과학회 2008 Journal of medicinal food Vol.11 No.4

Effects of a Cordia salicifolia (porangaba) extract on the labeling of blood cells (BCs) with technetium-99m (99mTc) and on the morphology of red BCs were evaluated. Labeling of cellular and molecular structures with 99mTc depends on a reducing agent. Some physical characteristics, as visible absorbance spectrum, electric conductivity, and refractive index of this porangaba extract, were also determined. Blood samples from Wistar rats were incubated with porangaba extract or with 0.9% NaCl (control). Labeling of blood constituents with 99mTc was performed. Plasma (P) and BCs, both soluble (SF-P and SF-BC) and insoluble (IF-P and IF-BC) fractions, were separated. The radioactivity in each fraction was counted, and the percentage of radioactivity incorporated (%ATI) was calculated. Blood smears were prepared, fixed, and stained, and the morphology of the red BCs was evaluated. Data showed an absorbance peak at 480 nm and electric conductibility and refractive index concentration-dependent. Porangaba extract decreased significantly (P < .05) the BC, IF-P, and IF-BC %ATI, and no modifications were verified on the shape of red BCs. Analysis of the results reveals that some physical parameters could be useful to aid in characterizing the extract studied. Moreover, it is possible that chemical compounds of this extract could have chelating/redox actions or be capable of binding to plasma and/or cellular proteins.