Pentagonal Model Research Articles

Mechanical properties of methacylic acid/acrylonitrile copolymer foam

AbstractTo gain a foam plastic with excellent mechanical properties, tensile mechanical properties of methacylic acid/acrylonitrile (MAA/AN) copolymer and the corresponding foam microstructure were studied, and furthermore effects of the density, heat treatment, and crosslinking agent on foam mechanical properties were also discussed in this paper. The results reveal that the tensile strength and modulus of the copolymer after heat treatment are 64 MPa and 4.2 GPa respectively, when compared with 58 MPa and 3.8 GPa before heat treatment respectively. Foam mechanical properties are enhanced with the rise of the density, and the values tested accords with the theoretical values of pentagonal dodecahedron mechanical model basically. Foam mechanical properties are enhanced via heat treatment, and the same result can be observed after using the crosslinking agent (acrylamide) too. All these results indicate that MAA/AN copolymer foam possesses excellent mechanical properties, such as its tensile, 10% compressive and shear strength are 1.3, 0.8, and 0.8 MPa respectively when the foam density is 52 kg/m3. POLYM. ENG. SCI., 47:314–322, 2007. © 2007 Society of Plastics Engineers.

Calculation of specific surface area of foam metals using dodecahedron model

A pentagonal dodecahedron model of metal foam with open cells was considered for calculation of specific surface area of the high porosity metals. According to the pentagonal dodecahedron model the authors calculate the specific surface area of nickel foam samples with the cell size of ∼200 μm and find it approximate agreement with the results obtained by other methods, and the specific surface area of metal foams is correlated with cell size and the width of cell wall.

A forced five-dimensional factor analysis and concurrent validity of the Positive and Negative Syndrome Scale in Mexican schizophrenic patients

The heterogeneity of schizophrenic symptomatology is well documented. The positive–negative distinction is limited to cover the entire spectrum of schizophrenic psychopathology in order to describe the various clinical aspects of the disorder. Method: We recruited 150 schizophrenic patients between May 2002 and September 2003. Diagnoses were based on a structured clinical interview. The Positive and Negative Syndrome Scale (PANSS) was used to evaluate general psychopathology and symptom severity. For the concurrent validity of the pentagonal model of the PANSS, the BPRS, the CDSS, the OAS and the MMSE were used. Results: The forced five-factor principal-component analysis explained 53.4% of the total variance. There were significant correlations between the clinical rating scales and the five components of the PANSS. Discussion: Our data support a pentagonal model underlying the multidimensional schizophrenic symptomatology as assessed by the PANSS. The five-factor structure of the PANSS in Mexican schizophrenic patients enables further elucidation of the various clinical aspects of schizophrenia.

From pentagon to triangle: A cross‐cultural investigation of an implicit theory of giftedness

The present study examined an implicit theory of giftedness among pre‐service Chinese teachers. Participants were 189 second year students (preservice teachers, 74 male and 115 female, average age 20 years) from China Central Teachers’ University. Participants responded to an inventory based on Stemberg and Zhang's (1995) pentagonal implicit theory of giftedness and a simple questionnaire designed to cross‐validate two of the five criteria in the pentagonal model. Results indicated that in making judgments about giftedness, participants took into consideration three of the five criteria specified in the pentagonal model: excellence, productivity, and value. The excellence and productivity criteria were also confirmed by results from the simple questionnaire. Rarity and demonstrability, the two other criteria specified in the pentagonal model, were not taken into consideration by the participants in their evaluation of giftedness. Implications of these findings are discussed.

A confirmatory factor analytic evaluation of the pentagonal PANSS model

The positive and negative syndrome scale (PANSS) is widely used in psychiatric research. Reflecting this common use, considerable attention has been applied to the psychometric properties of this instrument. However, despite the publication of numerous studies and analyses, it remains uncertain how best data from the PANSS should be analysed to best model the symptoms of schizophrenia. A resolution to these concerns seemed to be offered following the publication in 1997 of a large multisite factor analysis that produced the ‘pentagonal model’, which has subsequently been included in the 2000 revision of the PANSS user manual. However, to date, an independent confirmatory analysis of this model has not yet been published. The aim of this study was to test this model in a new independent sample with confirmatory factor analysis (CFA). Independent confirmation of the fit of the model is required to ensure that its implementation is informed by confirmation of its psychometric properties. CFA was performed in a sample of 347 subjects with schizophrenia. The analysis found that the model had inadequate goodness of fit. The use of the pentagonal model has similar difficulties as earlier models and more research is required to ascertain the optimal method for measuring symptom dimensions in research and clinical settings.

Depressive, positive, negative and parkinsonian symptomsin schizophrenia.

Depressive symptoms are common in schizophrenia but their relationship to the positive and negative symptoms of the disorder and to extrapyramidal side-effects remains unclear. Considerable overlap exists between these symptom clusters when rated with traditional clinical rating scales. The aim of this study was to investigate the relationship of depressive to positive, negative and parkinsonian symptoms using the recent adaptation of the Positive and Negative Syndrome Scale (PANSS). The study involved the cross-sectional measurement of symptoms in a sample of community-treated and hospitalized patients with schizophrenia. Structured assessment included thePANSS, Montgomery-Asberg Depression Rating Scale (MADRS) and the Extrapyramidal Side Effects Rating Scale (ESRS). Depressive symptoms were common and correlated with positive and negative symptoms. These correlations were of a similar magnitude using either the original PANSS factor structure or the newer pentagonal model. The overlap between depressive and negative symptoms was limited to certain items in the rating scales and there was a clear separation between these symptom clusters and the other items. Parkinsonian symptoms also correlated with negative symptoms rated with either PANSS model. Use of the pentagonal PANSS model does not improve its capacity to distinguish between depressive and negative symptoms. Positive, negative, parkinsonian and depressive symptoms overlap using common rating scales but there appears to be some separation between these symptom domains when rated with individual scale items rather than total scale scores.

123I]Iomazenil SPECT benzodiazepine receptor imaging in schizophrenia

Deficient inhibitory neurotransmission of gamma-aminobutyric acid (GABA) has been implicated in the pathophysiology of schizophrenia based on postmortem studies. However, in vivo studies have shown predominantly negative or conflicting results. The goal of this study was to better characterize possible changes of the regional GABA A-benzodiazepine receptor distribution volume (BZR V 3-p) in schizophrenia in vivo, using a larger sample size than previous studies. Single photon emission computed tomography (SPECT) with [ 123I]iomazenil was used with a constant infusion paradigm to measure the BZR V 3-p under sustained radiotracer equilibrium conditions. Twenty-five patients with schizophrenia and 24 matched healthy control subjects were studied. Positive and Negative Syndrome Scale (PANSS) ratings were done in all subjects. Statistical parametric mapping (SPM) 96 was used to compare patients and control subjects as well as to study the relationship between SPECT results and composite PANSS scores based on two factorial models: the pentagonal model (positive, negative, dysphoric mood, activation, and autistic preoccupation factors) and the taxometric model (disorganized dimension). On the basis of ‘absolute’ values of V 3-p with no normalization for total brain uptake, the schizophrenic patients showed no signficant differences in BZR levels compared to the healthy control subjects. With a global normalization procedure, which is more sensitive to relative regional differences in activity, BZR V 3-p was significantly decreased in the patients in the left precentral gyrus (BA 6). The relative BZR V 3-p showed a significant positive correlation with duration of illness in the superior occipital gyri (BA 19). No significant correlations were observed between either absolute or relative BZR V 3-p and either age or any of the composite PANSS scores based on any of the two factorial models in either patients or control subjects. No significant differences were observed between cigarette smoking vs. non-smoking patients, nor between the patients on atypical antipsychotics vs. on typical antipsychotics vs. not on any antipsychotics. In general, no significant differences in BZR V 3-p were observed between patients and control subjects, except for a decrease in relative BZR V 3-p in the left precentral gyrus. Grey matter atrophy is unlikely to be the cause for this decrease. However, we could not exclude that possibility. The positive correlation with duration of illness might reflect the relative preservation of neurons expressing BZR in the superior occipital gyri as compared to other cortical brain regions in schizophrenia.

The pentagonal implicit theory of giftedness revisited: A cross‐validation in Hong Kong

This article addresses the cross‐cultural generalization of the pentagonal implicit theory of giftedness (Sternberg & Zhang, 1995) as well as differential expectations regarding excellence for girls versus boys. First, we used an instrument based on the pentagonal theory with a sample of in‐service and pre‐service teachers at the University of Hong Kong. Second, we administered a questionnaire designed to assess conceptions of “excellence,” one of the attributes for giftedness described in the pentagonal model, to a different sample of in‐service and pre‐service teachers at the same university. We found a good fit of the pentagonal model to the data collected, paralleling results obtained in the U.S. We also found, however, that in Hong Kong, however, unlike in the U.S., participants had higher expectations of excellence for boys than for girls. These outcomes have implications for identification, instruction, and programming for the gifted.

Pentagonal Model of Membrane Channel of Na,K-ATPase. Computer Simulations of Structure and Electrostatic Properties

Computational modeling of the membrane channel of a sodium pump (Na,K-ATPase) is performed and the role of selected amino acids in binding of sodium ions is discussed. The channel is build as a pentameric 10-helix bundle. The transmembrane a-helices are determined from hydropathy calculations. The spatial arrangement of transmembrane a-helices is chosen according to the size of a pore, intersegment loops geometry, and orientation hydrophobicities of transmembrane segments. The latter property provides the numerical estimate of the distribution of the hydrophobic properties at the helical wheels. The model system involves the peptide part and 150 water molecules that soak the pore. The channel structure is submitted to geometry minimization and molecular dynamics relaxation. The relative stability of the channel states with the negatively charged acidic residues belonging to the pore interior decrease in the order Glu-334 > Asp-810 > Glu-785 > Asp-814. The estimated binding energies of 1-3 Na+ ions with the channel with the ionized Glu-334 and Glu-785 amino acids are in the range allowing the exothermic complexation.

Pentagonal Model of Membrane Channel of Na,K-ATPase. Computer Simulations of Structure and Electrostatic Properties

Pentagonal Model of Membrane Channel of Na,K-ATPase. Computer Simulations of Structure and Electrostatic Properties

Industrial Policy Partners: explaining the European level firm-Commission interplay for electronics

This paper explores the relationship which exists between the European Commission and electronics transnational corporations (TNCs) in the creation and control of European Community (EC) industrial policy. The objective is to understand and to provide a framework of analysis for the processes of Commission–TNC relations. This necessitates understanding how the various organisations interact and how they influence one another (Wilks and Wright, 1987: 275). This policy-making power interplay is best conceptualised in terms of the Pentagonal Diplomacy model. It is acknowledged that other actors, especially national governments, are important players in EC industrial policy formulation. We argue however, that EC electronics policy is shaped and guided mainly by the Commission and a group of large firms. This process occurs through what Wilks and Wright describe as “informal relationships” (1987: 286), the effects of which are often underestimated in analyses of EC industrial policy.

An easily constructed pentagonal pyramid model

A model of a pentagonal pyramid, which is useful for teaching stereochemistry can be made easily by using a sealed empty envelope.

An easily constructed bicapped pentagonal prism model

A model of a bicapped pentagonal prism, which is useful for teaching stereochemistry can be made easily by using a sealed empty envelope.

The Al-Mn decagonal phase Part 3. Diffraction pattern simulation based on a new index scheme

Abstract Abstract A proposal to abandon the current sophisticated index scheme of the Al-Mn decagonal phase has recently been advanced (Fitz Gerald, Withers, Stewart and Calka 1987), in favour of a new straightforward description. This description is based on a periodic stacking of Penrose lattices which are two-dimensional, using the natural in-plane (quasi-periodic) a 6 (n = 1 to 5) and (periodic) a 6 vectors as its basis. It affords a simpler description than the currently adopted system which is based on the lower and upper edge vectors of a (distorted icosahedral) pentagonal bipyramid model, with useful advantages for example in comparing vectors of identical quasiperiodic but different periodic components. Computing the diffraction pattern is straightforward in our description, and our simulations show excellent agreement with patterns recorded experimentally at various projection angles.

The pentagonal dodecahedral model of vitreous silica and its compatibility with diffraction experiments

AbstractROBINSON's pentagonal dodecahedral model represents a very interesting non‐crystallographical heterogeneous description of atomic arrangement in vitreous silica. The pair function distribution of this model has been calculated and compaired with a measured pair function distribution of vitreous silica. The pentagonal dodecahedral model seems to be a little better than cristallite models but cannot bear comparison with the continuous random network model.

The Systemic Power

World events in recent years increasingly reveal that some of the concepts designed to explain international affairs are no longer operational. The East-West conflictual relationship defined in ideological terms (on both sides) could hardly help us understand President de Gaulle's shoutings against 'American-Soviet hegemony' and the harsh Sino-Soviet polemics; nor could one explain in such terms the joint Soviet-American nuclear treaties or the official Chinese statement at the U.N. that the People's Republic of China belongs to the Third World. The other predominant school the power theorists were startled last winter when a number of backward kingdoms and sheikdoms, surviving from another age, carried out an oil embargo that shook some of the rich and powerful metropoles to their very foundations. And how can one account, in terms of bipolar or pentagonal world models, for the estimation that in the next decade the oil exporting countries will accumulate over half a trillion dollars, which would actually mean control over the bulk of the liquid capital available in the whole world? Indeed, we must think anew and formulate new concepts that would allow us to understand the meaning of these unprecedented phenomena and to see where they take us. It is the assumption of this study that in a shrinking world, with its national units more and more interdependent and caught in a dense network of mutual relations, multiple interaction and crosscutting coalitions, a new type of power is emerging, utterly different from the existing structural one embodied in the nation-state: the systemic power. To start with, let us keep in mind that in international politics there is no center of authority and power, like the state in internal politics, and that this vacuum has been filled throughout history by various formulae of centralization of power supposed to perform, in the international arena, the ordermaintaining and integration functions of the state inside society. While in the old times vacuum generated hegemonal powers (Pax Romana, Pax Britannica) or balance-ofpower schemes (Concert of Europe), after World War II most analysts used the bipolar model with the two superpowers, the US and USSR, then the triangular model (including China in the big game), and more recently the pentagonal model (adding Western Europe and Japan). What is the meaning of this latest diplomatic balance in which one center of power, Japan, though a global eceonomic power, has no significant military force, and another, Western Europe, is a loose union of nine states with a certain degree of economic integration in the EEC and a military force that is neither independent nor sufficiently strong to counter the superpowers in the global strategic game? Apparently, the changes that have taken place in world politics have affected not only the relationship of forces between the major actors, but the dynamics of power itself, in the sense that the relative weight of the military component of power has been reduced in favor of the economic, technological and politico-diplomatic components that have grown accordingly. This is not to say that force will be eliminated from the attributes of power; in spite of its setbacks

Unit fibril models derived from the molecular topography of collagen.

AbstractThe geometrical properties of collagen molecules place certain restrictions on possible three‐dimensional packing models. With certain reasonable assumptions involving the macromolecular structure of collagen, a model for the surface topography of the monomeric unit is developed and two possible models for molecular packing, one hexagonal and the other non‐hexagonal, are inferred. The non‐hexagonal packing model is identical to the pentagonal unit fibril first postulated by J. W. Smith on different grounds, while the hexagonal model is one of three previously suggested by us on more general assumptions. The two models are compared to available data on collagen packing, and the bulk of the evidence would seem to favor the pentagonal model.

School of Holistic Development: A Case Study

Holistic development of students for life transformation through process of educational metamorphosis with the help of pentagonal model of integral education is the unique program of School of Holistic Development (SHD). With a vision to create and nurture the ‘Wholesome’ Personality of student to build ‘Winning Personalities and Comprehensive Global Professionals’ enabling them to meet challenges of career as well as life with skills, sensibility and sense of responsibility towards society and humanity by emphasizing on enhancing Employability of students by building Skills, Competencies and Multiple intelligence, Character, Values of Life are the objectives of the program. Inspired with this Indic approach SHD has designed a unique model of creating and fostering wholesome personalities through Integral Education. Indic wisdom of personality talks of five aspects (Panch Kosh). This ‘Pentagon’ of five ‘Koshas’ emphasizes five-dimensional development like Physical, Emotional, Psychological and Intellectual Development and Spiritual Awakening. This program at SHD works at levels of senses and for healthy body; mind, emotions and psychology; skills and competencies for technical and intellectual enhancement, responsible behavior towards society and environment, yoga, values and spirituality to achieve the final objective of self-realization, self-discovery and finding out one’s own real-life purpose. The paper discusses the case study of SHD, launched by MIT Arts Design Technology University, Pune, India gives details of conceptual framework, vision, mission, objectives, methodology and tools adopted under SHD for holistic development of students and also compares and gives similarities between SHD and the National Educational Policy of Indian 2019.

On the structure of vitreous SiO 2— I. A new pentagonal dodecahedral model

While many of the features of the Warren-Zachariasen theory of the structure of silica seem to have stood the test of time a number of its details are coming more and more to be questioned. It is shown that an alternative form of the random hypothesis for such structures can be given. In essence this reformulation is stated in terms of a network built up of a jumble of n sided polyhedra each face of which is a polygon with m faces. The silicon atoms are located on the vertices of the polyhedra; the oxygen atoms lie between the Si but not necessarily along the edges. It is shown that n must be close to 12 and m close to 5. A formal pentagonal dodecahedral model (PDM) is then proposed which has the great advantage of being amenable to calculation. Since the individual pentagonal dodecahedra (pd), when stacked, do not quite fill space, some distortion is necessary; even under these circumstances space can be filled only for limited volumes. The resulting distortion can be evaluated from the density and from the volume increases found experimentally when foreign oxides, whose cations are smaller in radius than Pb 2+ are added to silica to form glasses. The pentagonal dodecahedral model (PDM) thus leads to a grained textured structure composed of tiny cylinders whose packing fraction is very high due to the relatively large number of cross-grain Si-O-Si linkages. The model yields an X-ray diffraction pattern in agreement with that found experimentally.

On the structure of vitreous SiO 2; I. A new pentagonal dodecahedral model : Howard A. Robinson (Department of Physics, Adelphi University, Garden City, New York, U.S.A.)

On the structure of vitreous SiO 2; I. A new pentagonal dodecahedral model : Howard A. Robinson (Department of Physics, Adelphi University, Garden City, New York, U.S.A.)