Regularity criterion on weak solutions to the Navier-Stokes equations

Sadek Gala 대한수학회 2008 대한수학회지 Vol.45 No.2

Consider a weak solution u of the Navier-Stokes equations in the class L² [수식]. We establish a new approach to treat the regularity problem for the Navier-Stokes equation in term of the multiplier space X₁(Rd). Consider a weak solution u of the Navier-Stokes equations in the class L² [수식]. We establish a new approach to treat the regularity problem for the Navier-Stokes equation in term of the multiplier space X₁(Rd).

CHARACTERIZATION OF THE MULTIPLIERS FROM H r TO H −r

Sadek Gala,Yoshihiro Sawano 대한수학회 2013 대한수학회보 Vol.50 No.3

In this paper, we will provide an alternative proof to char- acterize the pointwise multipliers which maps a Sobolev space . H r (Rd) to its dual . H −r (Rd) in the case 0 < r < d 2 by a simple application of the definition of fractional Sobolev space. The proof relies on a method introduced by Maz’ya-Verbitsky [9] to prove the same result.

Do Fixed Exchange Rates Cause Greater Integration?

( Amr Sadek Hosny ) 세종대학교 경제통합연구소 2013 Journal of Economic Integration Vol.28 No.4

A classic argument in favor of a fixed exchange rate regime (ERR) has been the promotion of international trade between the pegging country and its base country. Results from previous literature point to a significant and highly positive effect of adopting a fixed ERR on bilateral trade between any given country pair. In this paper, it is argued that these results should not be interpreted as causal effects, since countries do not typically choose their ERR independently of their trade flows. This source of selection bias can be greatly reduced by using the matching approach in estimating treatment effects. Estimates of the effect of fixed ERR using this procedure are close to the ordinary least squares estimates reported in the literature, suggesting that there is little bias in these conventional estimates. These findings are robust to using different propensity score matching methods.

Between ambitions and challenges, what are the chances of the BRICS bloc issuing its unified currency?

Mohamed Sadek Abozaid 부산외국어대학교 지중해지역원 2024 아프리카학 연구 Vol.4 No.1

The BRICS bloc is considered one of the most recent global blocs that is concerned with economic cooperation among its members. The “BRICS” bloc is one of the forms of international governmental organizations. The BRICS bloc includes enormous economic and human capabilities. It has large geographical areas and a large and diverse population, especially with the acceptance of membership of five other countries in the bloc. The bloc's countries present themselves to the world as emerging countries seeking to achieve sustainable development away from any existing political affiliations or blocs. The bloc aims to enhance cooperation between its countries to achieve economic development based on advanced technology and skills development and work to improve the position of developing and emerging countries in international financial institutions and develop the performance of multilateral trading systems to ensure the existence of a multipolar global system and reform international financial and economic institutions, thus ending the dominance of the US dollar over the capabilities of the global economy. The study concluded that it is difficult to end the dominance of the US dollar over the capabilities of the global economy currently and in the near and medium future, and that the goal of issuing a unified currency for the BRICS bloc remains largely distant.

REGULARITY CRITERION ON WEAK SOLUTIONS TO THE NAVIER-STOKES EQUATIONS

Gala, Sadek Korean Mathematical Society 2008 대한수학회지 Vol.45 No.2

Consider a weak solution u of the Navier-Stokes equations in the class $L^2((0,T);X_1(\mathbb{R}^d)^d)$. We establish a new approach to treat the regularity problem for the Navier-Stokes equation in term of the multiplier space $X_1(\mathbb{R}^d)$.

apoptosis in N-acetyl-p-aminophenol-induced liver injury in mice is tissue factor dependent

Mohamed Sadek Abdel-Bakky,Gouda Kamel Helal,El-Sayed Mohamed El-Sayed,Elham Amin,Abdulmajeed Alqasoumi,Ahmad Alhowail,Eman Sayed Said Abdelmoti,Ahmed Saad Saad 대한생리학회-대한약리학회 2021 The Korean Journal of Physiology & Pharmacology Vol.25 No.5

Tissue factor (TF) activates the coagulation system and has an important role in the pathogenesis of various diseases. Our previous study stated that retinoid receptors (RAR-α and RXR-α) are released as a lipid droplet in monocrotaline/ lipopolysaccharide-induced idiosyncratic liver toxicity in mice. Herein, the interdependence between the release of retinoid receptors RAR-α and RXR-α and TF in Nacetyl- p-aminophenol (APAP)-induced mice liver toxicity, is investigated. Serum alanine transaminase (ALT) level, platelet and white blood cells (WBCs) counts, protein expression of fibrin, TF, cyclin D1 and cleaved caspase-3 in liver tissues are analyzed. In addition, histopathological evaluation and survival study are also performed. The results indicate that using of TF-antisense (TF-AS) deoxyoligonucleotide (ODN) injection (6 mg/kg), to block TF protein synthesis, significantly restores the elevated level of ALT and WBCs and corrects thrombocytopenia in mice injected with APAP. TF-AS prevents the peri-central overexpression of liver TF, fibrin, cyclin D1 and cleaved caspase- 3. The release of RXR-α and RAR-α droplets, in APAP treated sections, is inhibited upon treatment with TF-AS. In conclusion, the above findings designate that the released RXR-α and RAR-α in APAP liver toxicity is TF dependent. Additionally, the enhancement of cyclin D1 to caspase-3-dependent apoptosis can be prevented by blocking of TF protein synthesis.

ON THE IMPROVED REGULARITY CRITERION OF THE SOLUTIONS TO THE NAVIER-STOKES EQUATIONS

Gala, Sadek Korean Mathematical Society 2020 대한수학회논문집 Vol.35 No.1

This note deals with the question of the regularity of (Leray) weak solutions of the Navier-Stokes equations in terms of the pressure. This criterion improves on the existing results.

CHARACTERIZATION OF THE MULTIPLIERS FROM Ḣ_r TO Ḣ_-r

Gala, Sadek,Sawano, Yoshihiro Korean Mathematical Society 2013 대한수학회보 Vol.50 No.3

In this paper, we will provide an alternative proof to characterize the pointwise multipliers which maps a Sobolev space $\dot{H}^r(\mathb{R}^d)$ to its dual $\dot{H}^{-r}(\mathb{R}^d)$ in the case 0 < $r$ < $\frac{d}{2}$ by a simple application of the definition of fractional Sobolev space. The proof relies on a method introduced by Maz'ya-Verbitsky [9] to prove the same result.

Density, viscosity, and surface tension of water+ethanol mixtures from 293 to 323K

Ibrahim Sadek Khattab,Abolghasem Jouyban,Farzana Bandarkar,Mohammad Amin Abolghassemi Fakhree 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.6

Density, viscosity, and surface tension of liquids are important physicochemical properties which affect mass and heat transfer in solutions. The density, viscosity, and surface tension of binary mixture of water+ethanol at 293, 298, 303, 308, 313, 318, and 323 K are reported and compared with the available literature data. The findings of these comparisons show how the measured data are reproducible from different laboratories. The molar volume of water+ethanol mixtures are also calculated using measured density values. The Jouyban-Acree model was used for mathematical correlation of the data. The relative deviation (RD) was used as an error criterion and the RD values for correlation of density, viscosity, surface tension and molar volume data at investigated temperatures are 0.1±0.1%, 10.4±9.5%,4.2±3.6%, and 0.3±0.3%, respectively. The corresponding RDs for the predicted properties after training using the experimental data at 298 K are 0.2±0.2%, 14.1±15.8%, 5.4±4.6% and 0.4±0.3%, respectively, for density, viscosity,surface tension, and molar volume data. This study shows that the Jouyban-Acree model can correlate/predict physicochemical properties of the mixtures of solvents at different temperatures with acceptable error in calculation.

Type of tooth movement during en masse retraction of the maxillary anterior teeth using labial versus lingual biocreative therapy in adults: A randomized clinical trial

Mais M. Sadek,Noha E. Sabet,Islam T. Hassan 대한치과교정학회 2019 대한치과교정학회지 Vol.49 No.6

Objective: The objective of this two-arm parallel trial was to compare the type of tooth movement during en masse retraction of the maxillary anterior teeth using labial versus lingual biocreative therapy. Methods: Twenty-eight subjects were randomized in a 1 : 1 ratio to either the labial or lingual group. En masse anterior retraction was performed using labial biocreative therapy in group A and lingual biocreative therapy in group B. Cone beam computed tomography scans were taken before and after retraction and the primary outcome was the type of tooth movement during anterior retraction. Data were analyzed using paired t -tests for comparisons within each group and independent-sample t-test for comparison of the mean treatment changes between the two groups. Results: Significant differences were found between the two groups in relation to the type of tooth movement (labiolingual inclination of the central incisor; mean difference, 5.85 ± 1.85o). The canine showed significant distal tipping in the lingual group (mean difference, 6.98 ± 1.25o). The canine was significantly more intruded in the lingual group (mean difference, 1.67 ± 0.49 mm). Good anchorage control and significant soft tissue changes occurred in both groups. No serious adverse effects were detected. Conclusions: With a 10-mm retraction hook, the labial biocreative technique with the reverse curve overlay provided anterior retraction with good torque control, while in the lingual group, anterior retraction occurred with controlled tipping movement with significant distal tipping and intrusion of the canine (trial registration: The trial was registered at ClinicalTrials.gov [NCT03239275]).