Mathematics, Statistics & Physics: Recent submissions

Now showing items 41-60 of 738

    • Synthetic efforts and applications of metal selenide nanotubes 

      Hussain, Raja Azadar; Hussain, Iqtadar ( Elsevier , 2021 , Article)
      Properties of metal selenides are dependent on their band gaps which can be tuned with size and morphology. Nanotubes particularly are important for their enhanced surface area and reaction sites. Extensive experimental ...

    • Exploring EMI in STEM disciplines: a case study of KAIST 

      Jo, Charmhun; Roshan, Morve K.; Mansour, Nasser ( Taylor and Francis Ltd. , 2024 , Article)
      This research aims to overview the English-medium instruction (EMI) situation in Korean Higher education (HE), briefly describing and studying HE policies and examining their impact on Korean teachers and students. The ...

    • Factors impacting science and mathematics teachers’ competencies and self-efficacy in TPACK for PBL and STEM 

      Mansour, Nasser; Said, Ziad; Abu-Tineh, Abdullah ( Modestum LTD , 2024 , Article)
      Science and mathematics teachers face the dual challenge of mastering subject-specific expertise and developing the pedagogical skills necessary for implementing integrated science, technology, engineering, and mathematics ...

    • Membrane solubilization in erythrocytes as a measure of radiation exposure to fast neutrons 

      Monem, A Soltan; Ali, Fadel M; Al-Thani, Noura J J.; Ali, Samira A ( IOP Publishing , 1999 , Article)
      Membrane solubilization and osmotic fragility of rat erythrocytes irradiated in vivo with fast neutron fluences ranging from 106 to 5 x 107 n cm-2 using a 252Cf source were measured instantaneously using a light scattering ...

    • Microstructural investigation of gamma-irradiated ultra high molecular weight polyethylene in nitrogen atmosphere 

      Al-Maadeed, M.; Al-Thani, N. J.; Bader, M. ( Trans Tech Publications , 2010 , Conference Paper)
      In this paper the results of structural changes in ultra high molecular polyethylene (UHMWPE) upon gamma irradiation and storage in nitrogen environment are reported. Based on differential scanning calorimetry (DSC), wide ...

    • Effect of gamma irradiation on the microstructure and morphology of polyethylene oxide and polyvinyl alcohol blends 

      Al-Maadeed, M.; Al-Thani, N. J. ( Trans Tech Publications , 2010 , Conference Paper)
      Thin films of a blend of 90, 75, 50 (wt/wt%) percentage of polyethylene oxide and polyvinyl alcohol were synthesized and irradiated with 5, 25, 50, 100 and 200 kGy. The presence of PVA leads to diffusion controlled mechanism ...

    • Investigating the individual interests of undergraduate students in STEM disciplines 

      Ammar, Mohammad; Siby, Nitha; Khalili, Sara; Al-Thani, Alshayma N.; Sellami, Abdellatif; ... more authors ( Frontiers Media SA , 2024 , Article)
      Despite massive investments in the education sector to empower youth in Qatar, a vital concern remains to retain students in science, technology, engineering, and mathematics (STEM) disciplines at the undergraduate level. ...

    • Characterizing the effective reproduction number during the COVID-19 pandemic: Insights from Qatar's experience 

      Bsat, Raghid; Chemaitelly, Hiam; Coyle, Peter; Tang, Patrick; Hasan, Mohammad R.; ... more authors ( Edinburgh University Global Health Society , 2022 , Article)
      Background The effective reproduction number, Rt, is a tool to track and understand pandemic dynamics. This investigation of Rt estimations was conducted to guide the national COVID-19 response in Qatar, from the onset of ...

    • Kappa-Distributed Electrons in Solar Outflows: Beam-Plasma Instabilities and Radio Emissions 

      Lazar, M.; López, R. A.; Poedts, S.; Shaaban, S. M. ( Springer Science and Business Media B.V. , 2023 , Article)
      Electrostatic (ES) wave instabilities are assumed to be at the origin of radio emissions from interplanetary shocks, and solar coronal sources are most likely induced by electron beams, more energetic but less dense than ...

    • Instability of Langmuir-beam waves: Kappa-distributed electrons 

      Lazar, M.; López, R. A.; Poedts, S.; Shaaban, S. M. ( American Institute of Physics Inc. , 2023 , Article)
      In space plasmas, electron populations exhibit non-equilibrium velocity distributions with high-energy tails that are reproduced by the Kappa power-laws and contrast with the Maxwellian distributions often used in theoretical ...

    • An exploratory study on medications in Qatar homes 

      Kheir, N.; El Hajj, M.S.; Wilbur, K.; Kaissi, R.M.L.; Yousif, A. ( Dove Medical Press Ltd , 2011 , Article)
      Background: Drug therapy is the most often used intervention for treatment and prevention of disease. However, if used inappropriately, drugs can cause more harm than good. Improper drug storage and disposal can have a ...

    • Ion beam modification of surface properties of polyethylene 

      Andrzej, Turos; Jagielski, Jacek; Piątkowska, Anna; Bieliński, Dariusz; Ślusarski, Ludomir; ... more authors ( Elsevier , 2003 , Conference Paper)
      Improvement of polymer tribological properties is an essential issue for their application when used as parts of machines or artificial human joints. Ion implantation is a very promising technique in this respect. This ...

    • Mechanical and thermal properties of gamma-ray irradiated polyethylene blends 

      Mariam, Al-Ali; Madi, N.K; Al Thani, Nora J.; El-Muraikhi, M.; Turos, A. ( Elsevier , 2003 , Conference Paper)
      In this work, the results obtained by gamma-ray irradiation of polyethylene (PE) blends are presented. The blends were produced by injection molding at 220°C with different compositional ratios, i.e. 100/0, 15/85, 25/75, ...

    • Compositional transformations in ion implanted polymers 

      A.M., Abdul-Kader; Turos, A.; Grambole, D.; Jagielski, J.; Piątkowska, A.; ... more authors ( Elsevier , 2005 , Conference Paper)
      Changes of surface layer composition produced by ion bombardment of polyethylene and polypropylene samples were studied. These materials are under consideration for load bearing surfaces in biological and technical ...

    • Study on ferroelastic characteristics of gamma irradiated lithium potassium sulfate crystal 

      N.K, Madi; Kassem, M.E; El-Muraikhi, M; El-Khatib, A.M ( Elsevier , 1999 , Article)
      A detailed study of the optical absorption vs. γ-irradiation dose for lithium potassium sulfate crystal, LiKSO4 cut out perpendicular to x, y and z directions is presented. The optical density was measured within the ...

    • Temperature and electric field effects on the dielectric dispersion of modified polyvinyl chloride 

      M.E., Bassiouni; Al-Shamy, F.; Madi, N.K.; Kassem, M.E. ( Elsevier , 2003 , Article)
      The effect of electric field on the dielectric dispersion of modified polyvinyl chloride (PVC) has been investigated. The applied direct current (DC) field strength was ranging from 0 to 104 V cm−1. The complex permitivity ...

    • Surface layer modification of ion bombarded HDPE 

      D., Bielinski; Lipinski, P.; Slusarski, L.; Grams, J.; Paryjczak, T.; ... more authors ( Elsevier , 2004 , Article)
      Press-moulded, high density polyethylene (HDPE) samples were subjected to ion bombardment and effects of the modification studied. He+ ions of energy 100 keV or Ar+ ions of energy 130 keV were applied in the range of dose ...

    • The effects of ion bombardment of ultra-high molecular weight polyethylene 

      A., Turos; Abdul-Kader, A.M.; Grambole, D.; Jagielski, J.; Piątkowska, A.; ... more authors ( Elsevier , 2006 , Article)
      Ion bombardment is a suitable tool to improve tribological properties of polymers. In this study UHMWPE samples were bombarded with 130keV He ions to the fluences ranging from 1×1014 to 2×1016cm−2. RBS and NRA techniques ...

    • Effectiveness of two and three doses of COVID-19 mRNA vaccines against infection, symptoms, and severity in the pre-omicron era: A time-dependent gradient 

      Layan, Sukik; Chemaitelly, Hiam; Ayoub, Houssein H.; Coyle, Peter; Tang, Patrick; ... more authors ( Elsevier , 2024 , Article)
      BackgroundVaccines were developed and deployed to combat severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. This study aimed to characterize patterns in the protection provided by the BNT162b2 and ...

    • Addressing bias in the definition of SARS-CoV-2 reinfection: implications for underestimation 

      Chemaitelly, Hiam; Ayoub, Houssein H.; Tang, Patrick; Yassine, Hadi M.; Al Thani, Asmaa A.; ... more authors ( Frontiers Media , 2024 , Article)
      Introduction: Reinfections are increasingly becoming a feature in the epidemiology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, accurately defining reinfection poses methodological ...