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Search Results: 1 - 10 of 11 matches for " Sarantos Psycharis "
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Exploring the Effects of the Computational Experiment Approach to the Epistemic Beliefs, the Motivation, the Use of Modeling Indicators and Conceptual Understanding in Three Different Computational Learning Environments
Sarantos Psycharis
Journal of Education and Training Studies , 2013, DOI: 10.11114/jets.v1i1.32
Abstract: Contemporary teaching and learning approaches expect students -at any level of education- to be active producers of knowledge. This leads to the need for creation of instructional strategies, learning environments and tasks that can offer students opportunities for active learning. Research argues that one of the most meaningful and engaging forms of active learning is modelling, that is using computational environments to build representational and epistemological models of the phenomena that are being studied, following the essential features of inquiry based science and mathematics education. The aim of the article is to investigate the impact of the computational experiment approach on: a) students’ learning performance, b) the use of modelling indicators c) the motives and d) the scientific epistemic beliefs. K-12 students in a Greek school participated in the experiment and the methodology of the computational experiment was implemented using three software tools, namely: the Modellus software, the Interactive Physics (IP) software and the Easy Java Simulator Software (EJS), in order to study the concept of the simple harmonic motion (equations of motion, dynamics and energy consideration). All applications were developed using the essential features of inquiry based science education in the framework of the computational approach methodology and the model was considered as the fundamental instruction unit. The findings suggest that the inquiry based computational experiment using Easy Java Simulator(EJS) is more effective in enhancing the conceptual understanding of students as well as the use of modelling indicators, and these results may have implications for the effectiveness of the computational experiment methodology when it is combined with the EJS Tools.
Discovery Learning and the Computational Experiment in Higher Mathematics and Science Education: A Combined Approach
Athanasios Kyriazis,Sarantos Psycharis,Konstantinos Korres
International Journal of Emerging Technologies in Learning (iJET) , 2009, DOI: 10.3991/ijet.v4i4.1044
Abstract: In this article we present our research for Discovery learning in relation to the computational experiment for the instruction of Mathematics and Science university courses, using the approach of the computational experiment through electronic worksheets. The approach is based on the principles of Discovery learning expanded with the principles of constructivist, socio–cultural and adult learning theories, the concept of computer based cognitive tools and the aspects on which the computational experiment is founded. Applications are presented using the software Mathematica and electronic worksheets for selected domains of Physics. We also present a case study, concerning the application of the computational experiment through electronic worksheets in the School of Pedagogical and Technological Education (ASPETE) during the spring semester of the academic year 2008–2009. Research results concerning the impact of the above mentioned issues on students’ beliefs and learning performance are presented.
Seismic reliability assessment of classical columns subjected to near-fault ground motions
Ioannis Psycharis,Michalis Fragiadakis,Ioannis Stefanou
Physics , 2013, DOI: 10.1002/eqe.2312
Abstract: A methodology for the performance-based seismic risk assessment of classical columns is presented. Despite their apparent instability, classical columns are, in general, earthquake resistant, as proven from the fact that many classical monuments have survived many strong earthquakes over the centuries. Nevertheless, the quantitative assessment of their reliability and the understanding of their dynamic behavior are not easy, because of the fundamental nonlinear character and the sensitivity of their response. In this paper, a seismic risk assessment is performed for a multidrum column using Monte Carlo simulation with synthetic ground motions. The ground motions adopted contain a high- and low-frequency component, combining the stochastic method, and a simple analytical pulse model to simulate the directivity pulse contained in near source ground motions. The deterministic model for the numerical analysis of the system is three-dimensional and is based on the Discrete Element Method. Fragility curves are produced conditional on magnitude and distance from the fault and also on scalar intensity measures for two engineering demand parameters, one concerning the intensity of the response during the ground shaking and the other the residual deformation of the column. Three performance levels are assigned to each engineering demand parameter. Fragility analysis demonstrated some of the salient features of these spinal systems under near-fault seismic excitations, as for example, their decreased vulnerability for very strong earthquakes of magnitude 7 or larger. The analysis provides useful results regarding the seismic reliability of classical monuments and decision making during restoration process.
Analysis of the Lee-Yang zeros in a dynamical mass generation model in three dimensions
I. Barbour,W. Franzki,N. Psycharis
Physics , 1998, DOI: 10.1016/S0920-5632(97)00881-5
Abstract: We investigate a strongly U(1) gauge theory with fermions and scalars on a three dimensional lattice and analyze whether the cintinuum limit might be a renormalizable theory with dynamical mass generation. Most attention is paid to the weak coupling region where a possible new dynamical mass generation mechanism might exist. There we investigate the mass of the composite fermion, the chiral condensate and the scaling of the Lee-Yang zeros.
Structural and Electrical Properties of the τ-(P-S,S-DMEDT-TTF)2 (AuCl2) (AuCl2)y Compound with (y ≈ 0.9)
Vassilis Psycharis,George A. Mousdis,Keizo Murata,George C. Papavassiliou
Crystals , 2012, DOI: 10.3390/cryst2031283
Abstract: The compound τ-(P- S, S-DMEDT-TTF) 2(AuCl 2) (AuCl 2) y (where P- S, S-DMEDT-TTF is the compound pyrazino-( S, S)-dimethyl-ethylenedithio-tetrathiofulvale) crystallizes in the non-centrosymmetric space group I-42d, with a = 7.3260(1) ? and c = 67.5487(12) ? (RT data) and remains tetragonal in the temperature range from RT to 100 K. This compound is a quasi-two-dimensional material and the relation of the lattice of the order part of the structure created by the donor molecules with that of the disordered anion lattice revealed by intense diffusion streaks give a value of y ≈ 0.9. In contrast to the Br and I analogs or the related compounds which contain the compound ethylenedioxy- S, S-dimethylenedithiotetrathiafulvalene (abbreviated as EDO- S, S-DMEDT-TTF) as donor and which exhibit anisotropic metallic behavior down to low temperature, this compound is anisotropic semiconductor in the same temperature range. The appearance of satellites on the diffraction images recorded below 110 K indicates a structural change. Resistivity measurements show that this material is a semiconductor with anisotropy σ a/σ c of ca. 400–1400 at room temperature.
In Search for Titanocene Complexes with Improved Cytotoxic Activity: Synthesis, X-Ray Structure, and Spectroscopic Study of Bis( -cyclopentadienyl)difluorotitanium(IV)
Elias Koleros,Theocharis C. Stamatatos,Vassilis Psycharis,Catherine P. Raptopoulou,Spyros P. Perlepes,Nikolaos Klouras
Bioinorganic Chemistry and Applications , 2010, DOI: 10.1155/2010/914580
Abstract: The 1 : 2 reaction of and AgF in yielded the fluoro analog (1) in almost quantitative yield ( is the cyclopentadienyl group). The coordination about the atom formed by two fluoro ligands and the centroids of the cyclopentadienyl rings is distorted tetrahedral. The compound crystallizes in the orthorhombic space group C2cm. The lattice constants are , and . The complex has been characterized by elemental analyses and spectroscopic (IR, NMR) data. A structural comparison of the four members of the family of complexes ( ) is attempted. 1. Introduction One of the first metal complexes discovered to exhibit biological activity has been cisplatin, [Pt(NH3)2Cl2] [1]. It is considered as one of the most efficient drugs for the treatment of certain types of cancer; however, drug toxicity and resistance limit its utilization for a broader range of diseases. In recent years, there has been a growing interest in the development of nonplatinum-based anticancer therapeutics. The main goal is to increase the variety of potential drugs, which may lead to higher activities enabling the administration of lower doses, attack of different types of tumour cells, solution of drug resistance problems, better selectivity and to lower toxicity. Non-platinum complexes may introduce numerous options for coordination numbers and geometries, oxidation states, affinity for certain types of biological ligands, and so forth, and may thus operate by different mechanisms. One class of such complexes are metallocene dihalides. Metallocene dihalides, [M( -C5H5)2X2] (M = Ti, V, Nb, Mo, Re; X = halide ligand; C5H5 = Cp, the cyclopentadienyl group), are a relatively new class of small hydrophobic organometallic anticancer agents that exhibit antitumour activities against cancer cell lines, such as leukaemias P388 and L1210, colon 38 and Lewis lung carcinomas, B16 melanoma, solid and fluid Ehrlich ascites tumours and also against human colon, renal and lung carcinomas transplanted into athymic mice [2–5]. Titanocene dichloride, [Ti( -C5H5)2Cl2], is the most widely studied metallocene compound as a cytotoxic anticancer agent, which means that it can selectively kill cancer cells, and was used in phase I and II clinical trials [6–13]. However, the efficacy of [Ti( -C5H5)2Cl2] in phase II clinical trials in patients with metastatic renal cell carcinoma [12] or metastatic breast cancer [13] was too low to be pursued. As titanium is present in many biomaterials, such as in food in the form of a whitening pigment, it is not unreasonable to conceive that it may be incorporated into drugs and into
Strongly coupled lattice gauge theory with dynamical fermion mass generation in three dimensions
I. M. Barbour,N. Psycharis,E. Focht,W. Franzki,J. Jersak
Physics , 1998, DOI: 10.1103/PhysRevD.58.074507
Abstract: We investigate the critical behaviour of a three-dimensional lattice $\chiU\phi_3$ model in the chiral limit. The model consists of a staggered fermion field, a U(1) gauge field (with coupling parameter $\beta$) and a complex scalar field (with hopping parameter $\kappa$). Two different methods are used: 1) fits of the chiral condensate and the mass of the neutral unconfined composite fermion to an equation of state and 2) finite size scaling investigations of the Lee-Yang zeros of the partition function in the complex fermion mass plane. For strong gauge coupling ($\beta < 1$) the critical exponents for the chiral phase transition are determined. We find strong indications that the chiral phase transition is in one universality class in this $\beta$ interval: that of the three-dimensional Gross-Neveu model with two fermions. Thus the continuum limit of the $\chiU\phi_3$ model defines here a nonperturbatively renormalizable gauge theory with dynamical mass generation. At weak gauge coupling and small $\kappa$, we explore a region in which the mass in the neutral fermion channel is large but the chiral condensate on finite lattices very small. If it does not vanish in the infinite volume limit, then a continuum limit with massive unconfined fermion might be possible in this region, too.
Surface barrier and bulk pinning in MgB$_2$ superconductor
M. Pissas,E. Moraitakis,D. Stamopoulos,G. Papavassiliou,V. Psycharis,S. Koutandos
Physics , 2001,
Abstract: We present a modified method of preparation of the new superconductor MgB$_2$. The polycrystalline samples were characterized using x-ray and magnetic measurements. The surface barriers control the isothermal magnetization loops in powder samples. In bulk as prepared samples we always observed symmetric magnetization loops indicative of the presence of a bulk pinning mechanism. Magnetic relaxation measurements in the bulk sample reveal a crossover of surface barrier to bulk pinning.
M?ssbauer study of Na$_{0.82}$CoO$_2$ (doped by 1% $^{57}$Fe)
M. Pissas,V. Psycharis,D. Stamopoulos,G. Papavassiliou,Y. Sanakis,A. Simopoulos
Physics , 2005,
Abstract: We studied by M\"{o}ssbauer spectroscopy the Na$_{0.82}$CoO$_2$ compound using 1% $^{57}$Fe as a local probe which substitutes for the Co ions. M\"{o}ssbauer spectra at T=300 K revealed two sites which correspond to Fe$^{3+}$ and Fe$^{4+}$. The existence of two distinct values of the quadrupole splitting instead of a continuous distribution should be related with the charge ordering of Co$^{+3}$, Co$^{+4}$ ions and ion ordering of Na(1) and Na(2). Below T=10 K part of the spectrum area, corresponding to Fe$^{4+}$ and all of Fe$^{3+}$, displays broad magnetically split spectra arising either from short-range magnetic correlations or from slow electronic spin relaxation.
Use of the 2-Pyridinealdoxime/N,N′-Donor Ligand Combination in Cobalt(III) Chemistry: Synthesis and Characterization of Two Cationic Mononuclear Cobalt(III) Complexes
Konstantis F. Konidaris,Catherine P. Raptopoulou,Vassilis Psycharis,Spyros P. Perlepes,Evy Manessi-Zoupa,Theocharis C. Stamatatos
Bioinorganic Chemistry and Applications , 2010, DOI: 10.1155/2010/159656
Abstract: The use of 2-pyridinealdoxime (paoH)/N, -donor ligand (L-L) “blend” in cobalt chemistry has afforded two cationic mononuclear cobalt(III) complexes of the general type [Co(pao (L-L) , where L-L = 1,10-phenanthroline (phen) and 2, -bipyridine (bpy). The CoC /paoH/L-L (1?:?2?:?1) reaction system in MeOH gives complexes [C (pao (phen)]Cl 2 O (1 2 O) and [C (pao (bpy)]Cl 1.5MeOH (2 1.5MeOH). The structures of the complexes were determined by single-crystal X-ray crystallography. The C ions are six-coordinate, surrounded by three bidentate chelating ligands, that is, two pa and one phen or bpy. The deprotonated oxygen atom of the pa ligand remains uncoordinated and participates in hydrogen bonding with the solvate molecules. IR data of the complexes are discussed in terms of the nature of bonding and the known structures. 1. Introduction Oximes and their metal complexes are of current interest because of their rich physicochemical properties, reactivity patterns, and potential applications in many important chemical processes in the fields of medicine [1, 2], bioorganic chemistry [3], catalysis [4], and electrochemical and electrooptical sensors [5]. In the treatment of organophosphate insecticide toxicity in man and animals, the use of acetylcholinesterase reactivators in conjunction with atropine has been found to be the most effective treatment [6]. Among various acetylcholinesterase reactivators, 2-pyridinealdoxime (paoH) is routinely used in human and veterinary practices. It is furthermore known that metal complexes of active drugs as ligands can have important pharmaceutical activities because of several factors. In fact, the field of medicinal inorganic chemistry emerged a long time ago [7], and it is based on certain principles that can be summarized as follows. Complexation with the metal protects the drug against enzymatic degradations because of the inertness of certain metal-ligand linkages. The metal complex can have better hydrophobicity/hydrophilicity properties than the free ligand and, through this, it can improve the transport processes in the tissues. In addition, the metal complex can release the active drug(s) in a specific organ, and its activity can be reinforced by the combination of effects from the ligands and from the metal residue. The application of these principles has already resulted in the design of successful metal-based drugs [8, 9]. Since 1905, when Tschugaeff introduced dimethylglyoxime as a reagent for the analysis of nickel, oxime ligands have played an important role in the continuing progress of coordination
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