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The aim of this study is to advance understading of teachers' and researchers' work, in particular its cultural specificities, from a resource perspective by exploring the issues and challenges faced during the translation of a theoretical framework, the Documentational Approach to Didactics (DAD), from Western (English and French) to East Asian languages (Chinese and Japanese). A basic assumption is that the challenges encountered while translating are driven by the cultural and linguistic differences that exist between the West and East. Adopting the perspective of the "Anthropological Theory of the Didactic" (ATD), we frame the translation work as a transposition process of research praxeology (a model of the researchers' practices and knowledge) from a Western to an Eastern institution. We investigate this process to identify cultural elements at different levels (school, society, civilization, etc.) using the ATD framework. After translating a DAD article into Chinese and Japanese separately, we then worked collaboratively to identify similar or diverse translation issues and investigated their origins. Consequently, the results revealed a considerable difference between the West and East, and ample similarities between China and Japan, especially in terms of the researchers' work and its relationship with the teachers' work.

This paper reports the results of an international comparative study conducted in Switzerland and Japan of an elementary school mathematics lesson. The principal aim of the study was to advance understanding of the cultural specificities of a mathematics lesson in its totality using concrete examples of lesson design and implementation and of how cultural factors within and beyond the classroom/school shape and produce mathematics lessons in a particular country. We analysed two Grade 4 mathematics lessons designed and implemented in Switzerland and Japan by pre-service teachers in the context of a project-based international exchange programme. The lesson, initially designed collaboratively by the pre-service teachers of the two countries, was ultimately realised in different ways in each country. Specifically, we found differences between the Japanese and Swiss lessons in the structure of the lesson and validation of solutions. To elucidate these differences and identify the cultural factors that yield them, we analysed the resources developed and used during lesson design and implementation (lesson plans, official documents, and textbooks). Furthermore, we discuss three aspects of mathematics lessons that account for the main characteristics of each lesson: collective or individualistic teaching and learning, problem-solving lessons, and distance between theory and practice.

Japanese lesson study was introduced to the West in the late 1990s. Certain widely disseminated publications and classroom videos, and also reports on international surveys of students achievement, led many to consider that Japanese mathematics teaching is highly creative and effective, with lesson study as a main explanatory factor. As a result, substantial efforts have been deployed in many countries to engage mathematics teachers in lesson study. In this paper, we argue that lesson study is but one element of a comprehensive Japanese "infrastructure" for developing teacher knowledge, both personal and shared, and that the functions and workings of any particular element in this infrastructure cannot be fully understood when viewed in isolation. In this paper, we offer a systemic (institutional) analysis of how these "infrastructure" elements interact in crucial ways. Specifically we study two episodes where a teacher's "practice research" is clearly motivated and supported by other infrastructural conditions, such as the possibility to present the outcomes at a regional teacher conference, and in a publication. Moreover, a central prerequisite for the creative part of "lesson planning" is a much more limited activity: the patient study and discussion of mathematical tasks and materials. This activity is also crucially supported by elements of the infrastructure.

The aims of the present study are two-fold. The first aim is to reveal the cultural and linguistic issues that need to be considered in the development of curricular content and sequencing for teaching mathematical proof in secondary schools in Japan. The second aim is to elaborate an epistemological perspective that may allow us to understand what constitutes proof in the curriculum of a given country, so that our results may be applied in international contexts. By doing so, we then elaborate a reference epistemological model which may allow us to understand what constitutes mathematical proof in different countries.

Lesson study is recognised as a cultural activity and its implementation in a context different from Japan is a complex process. Researchers' role in this process is assumed to be critical, although this has rarely been investigated. In this paper, we analyse a teaching experiment to introduce lesson study into a professional development course for prospective teachers at an Italian university, focusing our investigation on a group of researchers acting as teacher educators (didacticians). Using the anthropological theory of the didactic and meta-didactical transposition frameworks, we investigate their dual position as researchers and as teacher educators. We observe the evolution of the didacticians' teacher-education praxeology (a model of practice and knowledge) during their interactions with prospective teachers. The results indicate that the didacticians' teacher-education praxeology is distinguished, shaped, and actively influenced by their research praxeology. The results also imply that coordinating the two theoretical frameworks may guide the design and analysis of teachers' professional development courses. [ABSTRACT FROM AUTHOR]

This paper reports the results of an international comparative study on the nature of proof to be taught in geometry. Proofs in French and Japanese lower secondary schools were explored by analyzing curricular documents: mathematics textbooks and national curricula. Analyses on the three aspects of proof--statement, proof, and theory--suggested by the notion of Mathematical Theorem showed differences in these aspects and also differences in the three functions of proof--justification, systematization, and communication--that are seemingly commonly performed in these countries. The results of analyses imply two major elements that form the nature of proof: (a) the nature of the geometrical theory that is chosen to teach and (b) the principal function of proof related to that theory. This paper suggests alternative approaches to teach proof and proving and shows that these approaches are deeply related to the way geometry is taught.

In this paper, we first present a theoretical approach to study mathematics teacher knowledge and the conditions for developing it, which is firmly rooted in a systemic approach to didactic phenomena at large, namely the anthropological theory of the didactic. Then, a case of open lesson is presented and analysed, using this theoretical approach, to show how the format of open lesson contributes to the construction and diffusion of didactic knowledge in the community of mathematics teachers in Japan. The basic idea of this format is that teachers from other schools are invited to observe a class taught by a teacher then participate in a discussion session with him on the details of the lesson. For the case study, we analyse the lesson plan prepared for an open lesson, the observed lesson and the teachers' discussion. As a result, an open lesson session has been described as a specific form of post-didactic practice related directly to an actual observed lesson, and aiming specifically at elaborating the theoretical aspects of teacher's didactic practice in the lesson and beyond it.

In this paper, we analyze and compare two didactical designs for introducing primary school pupils to proportional reasoning in the context of plane polygons. One of them is well-documented in the literature; the other one is based on our own data and is accordingly presented and discussed in more detail in this paper. The two designs come from different cultural and intellectual environments: lesson study in Japan (implicitly based on the "open approach method") and "didactical engineering" in France (based on the theory of didactical situations). The general aim of our paper is to compare these two environments and their approaches to didactical design, basing our discussion on the concrete designs mentioned above. Clear differences among them are presented, while we also identify links which hold potential for integrating research and practice.

Arginine-rich peptide and Antennapedia are cell-penetrating peptides (CPPs) which have the ability to permeate plasma membrane. Deformation of the plasma membrane with CPPs is the key to understand permeation mechanism. We investigate the dynamics of CPP and the lipid bilayer membrane by coarse-grained simulation. We found that the peptide makes inverted micelle in the lipid bilayer membrane, when the attractive potential between the peptide and lipid heads is strong. The inverted micelle is formed to minimize potential energy of the peptide. For vesicle membrane, the peptide moves from the outer vesicle to the inner vesicle through the membrane. The translocation of the peptide suggests inverted micelle model as a possible mechanism of CPPs. [ABSTRACT FROM AUTHOR]

We computationally examined the structure of anti-tumour bicyclic hexapeptide RA-VII. This peptide adopts three conformations (confs.), A, B and C, in dimethyl sulfoxide (DMSO). Although it was experimentally reported that the structure of conf. A is important for anti-tumour activity, the dynamics of confs. A, B and C are not well known. We performed quantum chemical calculations and molecular dynamics (MD) simulations of RA-VII in DMSO. The MD simulations indicated two different local stable structures for conf. C: a structure containing a bent 18-membered ring and another structure containing a rotated peptide bond between Tyr6andd-Ala1. The root-mean-square fluctuation of the 14-membered ring for conf. A was larger than that for confs. B and C. Ala4formed intramolecular hydrogen bonds more often in conf. A than in the other conformations. A large number of hydrogen bonds and large structural fluctuations are important for the anti-tumour activity of RA-VII. Our results for the structural change of conf. C and the analysis of the dynamics for confs. A, B and C may contribute to the design of new analogues of cyclic peptides. [ABSTRACT FROM PUBLISHER]

Peptides with cell attachment activity are beneficial component of biomaterials for tissue engineering. Conformational structure is one of the important factors for the biological activities. The EF1 peptide (DYATLQLQEGRLHFMFDLG) derived from laminin promotes cell spreading and cell attachment activity mediated by α2β1 integrin. Although the sequence of the EF2 peptide (DFATVQLRNGFPYFSYDLG) is homologous sequence to that of EF1, EF2 does not promote cell attachment activity. To determine whether there are structural differences between EF1 and EF2, we performed replica exchange molecular dynamics (REMD) simulations and conventional molecular dynamics (MD) simulations. We found that EF1 and EF2 had β-sheet structure as a secondary structure around the global minimum. However, EF2 had variety of structures around the global minimum compared with EF1 and has easily escaped from the bottom of free energy. The structural fluctuation of the EF1 is smaller than that of the EF2. The structural variation of EF2 is related to these differences in the structural fluctuation and the number of the hydrogen bonds (H-bonds). From the analysis of H-bonds in the β-sheet, the number of H-bonds in EF1 is larger than that in EF2 in the time scale of the conventional MD simulation, suggesting that the formation of H-bonds is related to the differences in the structural fluctuation between EF1 and EF2. From the analysis of other non-covalent interactions in the amino acid sequences of EF1 and EF2, EF1 has three pairs of residues with hydrophobic interaction, and EF2 has two pairs. These results indicate that several non-covalent interactions are important for structural stabilization. Consequently, the structure of EF1 is stabilized by H-bonds and pairs of hydrophobic amino acids in the terminals. Hence, we propose that non-covalent interactions around N-terminal and C-terminal of the peptides are crucial for maintaining the β-sheet structure of the peptides. [ABSTRACT FROM AUTHOR]

Rational design of protein surface is important for creating higher order protein structures, but it is still challenging. In this study, we designedin silicothe several binding interfaces on protein surfaces that allow ade novoprotein–protein interaction to be formed. We used a computer simulation technique to find appropriate amino acid arrangements for the binding interface. The protein–protein interaction can be made by forming an intermolecular four-helix bundle structure, which is often found in naturally occurring protein subunit interfaces. As a model protein, we used a helical protein, YciF. Molecular dynamics simulation showed that a new protein–protein interaction is formed depending on the number of hydrophobic and charged amino acid residues present in the binding surfaces. However, too many hydrophobic amino acid residues present in the interface negatively affected on the binding. Finally, we found an appropriate arrangement of hydrophobic and charged amino acid residues that induces a protein–protein interaction through an intermolecular four-helix bundle formation. [ABSTRACT FROM PUBLISHER]

We investigate the structures of the Hras-GTP and the Hras-GDP complexes in water solvents in order to understand the mechanism of GTP hydrolysis in the Hras-GTP complex. We performed MD simulations of these complexes in order to study the positions and the orientations of water molecules around the guanosine nucleotides. Using trajectories we calculated the angular distribution of water molecules around the most distant phosphorus from guanosine in our previous work. It was shown that water molecules are distributed evenly in GTP, although unevenly in GDP. This suggests that the trigger of GTP hydrolysis is possibly the attack of water molecule to γ−phosphate from the appropriate direction. In this paper, in order to investigate the role of water molecules in GTP hydrolysis in detail, we calculate the orientation of water molecules. The distribution of the orientation is different between GTP and GDP. In order to investigate the cause of this difference, we examine the hydrogen bonds between water molecules and oxygen atom of the most distant phosphate from guanosine. We find that these hydrogen bonds are formed. We also find that the oxygen atom of hydrogen bond is determined by the position of the water molecule of hydrogen bond. [ABSTRACT FROM PUBLISHER]

We study the structures of the Hras-GTP complex and the Hras-GDP complex in water to investigate the mechanism of GTP hydrolysis of the Hras-GTP complex. We performed molecular dynamics simulations of these complexes to investigate the structures of these complexes using the potential parameters of AMBER ff03 and our potential parameters around Mg2+. Our simulations show that the averaged structure differences between the Hras-GTP complex and Hras-GDP complex are found in the switch I and II regions. In particular, in the switch II region, the α2 -helix of Hras-GDP is shorter than the α2 -helix of Hras-GTP. The averaged number of water molecules in the first hydration sphere in Hras-GDP complex is larger than that in Hras-GTP complex. The occurrence ratio of the duration time of waters in the first hydration sphere of PA has long tail both in Hras-GTP and in Hras-GDP. In Hras-GDP complex, β-phosphate is hard to be hydrolyzed, while the number of waters in the first hydration sphere is larger than those in Hras-GTP. This suggests that there is a special direction for the hydrolysis. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

We aim to construct a nano-fiber using proteins by mixing two kinds of proteins. The binding sites are expected to be formed between two α-helices of one protein and two α-helices of another protein. As model proteins, we use Lac repressor four helix protein (LARFH), sulerythrin, and 3-isopropylmalate dehydrogenase. With these proteins, we performed molecular dynamics (MD) simulations with a coarse-grained (CG) model. In MD simulations with the CG model for LARFH, we found that the molecules approached faster in the system where the mutant protein with positively charged amino acids was placed with the mutant protein with negatively charged amino acids than in the system containing two wild-type protein molecules. In the system with the variants, the number of contact interfaces with the positive variant-negative variant combination after 150 ns simulation is larger than that with the positive-positive variants combination or the negative-negative variants combination. Sulerythrin has two pairs of Fe2+ and Zn2+. Electronic structure calculation was performed around metal ions in sulerythrin. By electronic structure calculation for sulerythrin around metal ions, the electric charge and spin density were estimated. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

The structure and lateral pressure profile of the 1,2-dimyristoyl- sn-glycero-3-phosphatidylcholine (DMPC) and 1,2-distearoyl- sn-glycero-3-phosphatidylcholine (DSPC) lipid bilayers in the absence and presence of gramicidin A (GA) are studied by molecular dynamics simulation. Due to the hydrophobic mismatch between the GA and DSPC lipid bilayer, the chain conformation became disordered, and the hydrophobic thickness around the GA largely decreased to fit the length of hydrophobic core region of the GA. The polar headgroup of lipid was found to orient toward the membrane normal as the lipid approaches the GA. The surface tension around the polar headgroup region in the DMPC/GA membrane decreased due to the decrease of electrostatic interactions between the headgroups. The larger lateral pressure in the hydrophobic region of the DSPC/GA membrane causes the reduction of pore radius around the GA channel entrance, suggesting the decrease of ion accessibility to the GA channel entrance. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Hsp90 (90 kDa heat shock protein) is a molecular chaperon involved in protein folding and regulating the stability and activation state of many client proteins under stress and normal conditions. Hsp90 is an attractive target for the therapeutics against cancer and virus infectious diseases. Hsp90 undergoes large conformational changes during its functional cycle driven by ATP binding and hydrolysis to ADP at the N-terminal domain. ATP-binding and ADP-dissociation play key roles for the functions of Hsp90. All-atom molecular dynamics simulations of the N-terminal domain of human Hsp90 in complex with ADP are carried out to elucidate the dissociation process of ADP at atomic resolution. The MD simulations with the binding-distance constraint are performed. Our results show that ADP is dissociated from the binding pocket of Hsp90 with Mg2+, and that ADP has two possible conformation and two possible pathways in the dissociation process. © 2012 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

We investigated the deformation of lipid bilayer membrane by cell-penetrating peptide using coarse-grained molecular dynamics simulation. The simulations have been performed with different values of two parameters, strength of angle potential of lipid and strength of attractive interaction between peptide and lipid heads. We obtained the phase diagram of deformation of membrane and found that there are four kinds of structures such as surface dent, inverted micelle, double bilayer, and transmembrane. The results suggest that one peptide can make various structures on lipid bilayer membrane. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012 [ABSTRACT FROM AUTHOR]

To investigate the relationship between structural change and the solvation effect, we estimated the solvation free energy or excess chemical potential (ECP) of a globular protein by the energy representation method for the protein structure obtained by a molecular dynamic simulation. A large fluctuation of ECP was detected. The estimated ECP along the first principal component axis of protein fluctuation was accompanied with 'open-close' structural change, which indicated a smooth and progressive change in ECP. By performing a global water density analysis in the grid space, the water density at the hydration site had a strong correlation with the ECP. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012 [ABSTRACT FROM AUTHOR]

The effects of gramicidin A (GA) peptide on the structure of lipid bilayer were studied by molecular dynamics (MD) simulations in the absence and presence of GA peptide. The hydrophobic match between the GA and surrounding lipid bilayer was investigated by the MD simulations of four kinds of lipid bilayer systems: 1,2-dilauroyl- sn-glycero-3-phosphatidylcholine (diC12:0-PC), 1,2-dimyristoyl- sn-glycero-3-phosphatidylcholine (DMPC, diC14:0-PC), 1,2-dipalmitoyl- sn-glycero-3-phosphatidylcholine (diC16:0-PC), and 1,2-distearoyl- sn-glycero-3-phosphatidylcholine (DSPC, di18:0-PC). The observed hydrophobic thickness and order parameter increases, and the gauche conformation decreases in the presence of GA, being consistent with the experimental observations. The acyl chain structure of the DSPC membrane was sufficiently changed to match the length of GA peptide, resulting in a distortion of the membrane surface around the GA peptide. On the other hand, the minor structural changes of lipid and the small fluctuation of the GA were shown in the DMPC membrane. These results indicate that DMPC bilayer has a better hydrophobic match with the GA peptide than the other membranes. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012 [ABSTRACT FROM AUTHOR]

Recently, Teflon AF2400 (AF 1600, and AF 1601) was commercialized (DuPont Fluoroproducts, Wilmington, DE, U.S.A), that has a refractive index (1.29) lower than water (1.33), and which means that the wave-guiding of light is possible in water. In this study, we used Teflon AF 2400 as a waveguide capillary longpath cell for fluorometry. He-Cd and Ar+ lasers were used as the excitation source, at 325 nm and 514.5 nm respectively. The length of the capillary wave-guide cell was 18.70 cm. The was wound twice on a flat surface (loop diameters: 2 cm and 3 cm). The excitation was executed through the wave-guide cell and the fluorescence from the wound capillary cell wall was collected in a perpendicular direction to the loop. With excitation at 325 nm, the fluorescence intensity at 450 nm emitted from the cell wall decreased along with the increase in the refractive index of the solvent. This can be caused by attenuation of the source light due to absorption by the solvent. In our experiment, the solvent of higher refractive index has the higher absorption at 325 nm. On the other hand, the fluorescence intensity at 590 nm, with excitation at 514.5 nm, increases with increased refractive index of the solvent. This result shows that an increase in the refractive index of the solvent is preferable for maintaining the wave-guiding of the source light. Here, the characteristics of fluorescence spectrometry are discussed in terms of the collection of fluorescence from the wave-guide capillary cell wall. [ABSTRACT FROM AUTHOR]

Cell-penetrating peptides (CPPs) have an ability of internalisation to inner cells through plasma membrane. The plasma membrane and lipid bilayer in experiments contain negatively charged lipids. HIV-1 Tat peptide, which is one of the CPPs, has many arginines with positive charge, and strongly interacts with negatively charged lipids. We investigate the difference between neutral lipids, 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), and negatively charged lipids, 1,2-dioleoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] (DOPG), by all-atom molecular dynamics simulations. We found that the speed of binding of Tat to lipid membrane for DOPC is more than 10 times faster than the speed for DOPG. The Tat peptides bind to the lipid membrane by attractive interaction between arginine in Tat and phosphates in lipids. Comparing the number of phosphates binding to arginine, DOPG gives a larger number than DOPC. The differences indicate the importance of negatively charged lipids for the investigation of the property of CPPs. [ABSTRACT FROM PUBLISHER]

Although palmitoleic acid (C16:1) is associated with arrhythmias, and increases in an age-dependent matter, the effects of l -carnitine, which is essential for the transport of long-chain fatty acids into the mitochondria, are unclear. It has been postulated that l -carnitine may attenuate palmitate (C16:0)-induced mitochondrial dysfunction and the apoptosis of cardiomyocytes. The aim of this study was to elucidate the activity of l -carnitine in the prevention of the palmitoleic acid-induced mitochondrial membrane permeability transition and cytochrome c release using isolated cardiac mitochondria from rats. Palmitoleoyl-CoA-induced mitochondrial respiration was not accelerated by l -carnitine treatment, and this respiration was slightly inhibited by oligomycin, which is an inhibitor of ATP synthase. Despite pretreatment with l -carnitine, the mitochondrial membrane potential decreased and mitochondrial swelling was induced by palmitoleoyl-CoA. In the presence of a combination of l -carnitine and tiron, a free radical scavenger, there was attenuated mitochondrial swelling and cytochrome c release following palmitoleoyl-CoA treatment. We concluded that palmitoleic acid, but not palmitate, induces the cardiac mitochondrial membrane permeability transition despite the presence of l -carnitine. [ABSTRACT FROM AUTHOR]

Experimental observations indicate that the repulsion of particles is a factor that induces the transformation of vesicles containing multiple particles. Metropolis Monte Carlo simulations are performed with two models in which repulsive particles are enclosed inside a vesicle. The distribution of the particles and the effective bending coefficient and surface tension of the membrane are analyzed. The shape and internal structure of the vesicle containing the particles are investigated as the vesicle volume is decreased. It is revealed that the repulsive interaction between particles produces a layered structure and stiffens the membrane. When particles repulsively interact over a long range, the membrane takes on a dumbbell form.