Theoretical Estimation of Length Dependent In-Plane Stiffness of Single Walled Carbon Nanotubes Using the Nonlocal Elasticity Theory

In the present paper, Eringen's nonlocal elasticity theory is employed to evaluate the length dependent in-plane stiffness of single-walled carbon nanotubes (SWCNTs). The SWCNT is modeled as an Euler-Bernoulli beam and is analyzed for various boundary conditions to evaluate the length dependent in-plane stiffness. It has been found that the nonlocal scaling parameter has a significant effect on the length dependent in-plane stiffness of SWCNTs. It has been observed that as the nonlocal scale parameter increases the stiffness ratio of SWCNT decreases. In nonlocality, the cantilever SWCNT has high in-plane stiffness as compared to the simply-supported and the clamped cases.

Partially conserved axial-vector current inS-matrix theory

Mandelstam�s argument that PCAC follows from assigning Lorentz quantum numberM=1 to the massless pion is examined in the context of multiparticle dual resonance model. We construct a factorisable dual model for pions which is formulated operatorially on the harmonic oscillator Fock space along the lines of Neveu-Schwarz model. The model has bothm ? andm ? as arbitrary parameters unconstrained by the duality requirement. Adler self-consistency condition is satisfied if and only if the conditionm?2?m?2=1/2 is imposed, in which case the model reduces to the chiral dual pion model of Neveu and Thorn, and Schwarz. The Lorentz quantum number of the pion in the dual model is shown to beM=0.

Nota sullo status della gallina prataiola (Tetrax tetrax) nella Zona di Protezione Speciale Piana di Semestene, Bonorva, Macomer e Bortigali (Sardegna), 2007-2009

The little bustard Tetrax tetrax is a bird of agro-pastoral landscapes rapidly disappearing from most of Western Europe due to agricultural intensification. In Italy, the species is virtually extinct from the mainland but still occurs in Sardinia, where four Special Protection Areas (SPAs) have been designated in 2007 to protect the bustard and related habitat. In this note, we document a steep decline (between 50 and 87,5%) of the species during the last decade in one of those four SPAs, Plains of Semestene, Bonorva, Macomer and Bortigali. However, during summer 2009, a group of 17 individuals was found within the SPA, confirming that the species, although at low numbers (5-15 displaying males), still breeds successfully in the area. Potential limiting factors are also discussed. We urge to undertake conservation measures based on solid scientific evidence if the local population is to be saved from probable extinction in the near future.

Parametrized tests of post-Newtonian theory using Advanced LIGO and Einstein Telescope

General relativity has very specific predictions for the gravitational waveforms from inspiralling compact binaries obtained using the post-Newtonian (PN) approximation. We investigate the extent to which the measurement of the PN coefficients, possible with the second generation gravitational-wave detectors such as the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and the third generation gravitational-wave detectors such as the Einstein Telescope (ET), could be used to test post-Newtonian theory and to put bounds on a subclass of parametrized-post-Einstein theories which differ from general relativity in a parametrized sense. We demonstrate this possibility by employing the best inspiralling waveform model for nonspinning compact binaries which is 3.5PN accurate in phase and 3PN in amplitude. Within the class of theories considered, Advanced LIGO can test the theory at 1.5PN and thus the leading tail term. Future observations of stellar mass black hole binaries by ET can test the consistency between the various PN coefficients in the gravitational-wave phasing over the mass range of 11-44M(circle dot). The choice of the lower frequency cutoff is important for testing post-Newtonian theory using the ET. The bias in the test arising from the assumption of nonspinning binaries is indicated.

Superconformal transformations of theN=4 supersymmetric Yang-Mills theory

We obtain the superconformal transformation laws of theN=4 supersymmetric Yang-Mills theory and explicitly demonstrate the closure of the algebra.

From Habits to Social Structures : Pragmatism and Contemporary Social Theory

Pragmatism has sometimes been taken as a catchphrase for epistemological stances in which anything goes. However, other authors argue that the real novelty and contribution of this tradition has to do with its view of action as the context in which all things human take place. Thus, it is action rather than, for example, discourses that should be our starting point in social theory. The introductory section of the book situates pragmatism (especially the ideas of G. H. Mead and John Dewey) within the field and tradition of social theory. This introductory also contextualizes the main core of the book which consists of four chapters. Two of these chapters have been published as articles in scientific journals and one in an edited book. All of them discuss the core problem of social theory: how is action related to social structures (and vice versa)? The argument is that habitual action is the explanation for the emergence of social structures from our action. Action produces structures and social reproduction takes place when action is habitualized; that is, when we develop social dispositions to act in a certain manner in familiar environments. This also means that even though the physical environment is the same for all of us, our habits structure it into different kinds of action possibilities. Each chapter highlights these general insights from different angles. Practice theory has gained momentum in recent years and it has many commonalities with pragmatism because both highlight the situated and corporeal character of human activity. One famous proponent of practice theory is Margaret Archer who has argued that the pragmatism of G. H. Mead leads to an oversocialized conception of selfhood. Mead does indeed present a socialized view of selfhood but this is a meta-sociological argument rather than a substantial sociological claim. Accordingly, one can argue that in this general sense intersubjectivity precedes subjectivity and not the other way around. Such a view does not indicate that our social relation would necessarily "colonize" individual action because there is a place for internal conversations (in Archer s terminology); it is especially in those phases of action where it meets obstacles due to the changes of the environment. The second issue discussed has the background assumption that social structures can fruitfully be conceptualized as institutions. A general classification of different institution theories is presented and it is argued that there is a need for a habitual theory of institutions due to the problems associated with these other theories. So-called habitual institutionalism accounts for institutions in terms of established and prevalent social dispositions that structure our social interactions. The germs of this institution theory can be found in the work of Thorstein Veblen. Since Veblen s times, these ideas have been discussed for example, by the economist Geoffrey M. Hodgson. His ideas on the evolution of institutions are presented but a critical stance is taken towards his tendency of defining institutions with the help of rules because rules are not always present in institutions. Accordingly, habitual action is the most basic but by no means the only aspect of institutional reproduction. The third chapter deals with theme of action and structures in the context of Pierre Bourdieu s thought. Bourdieu s term habitus refers to a system of dispositions which structure social fields. It is argued that habits come close to the concept of habitus in the sense that the latter consists of particular kinds of habits; those that are related to the reproduction of socioeconomic positions. Habits are thus constituents of a general theory of societal reproduction whereas habitus is a systematic combination of socioeconomic habits. The fourth theme relates to issues of social change and development. The capabilities approach has been associated with the name of Amartya Sen, for example, and it underscores problems inhering in economistic ways of evaluating social development. However, Sen s argument has some theoretical problems. For example, his theory cannot adequately confront the problem of relativism. In addition, Sen s discussion lacks also a theory of the role of the public. With the help of arguments derived from pragmatism, one gets an action-based, socially constituted view of freedom in which the role of the public is essential. In general, it is argued that a socially constituted view of agency does not necessarily to lead to pessimistic conclusions about the freedom of action.

Coupling of surface acoustic waves propagating in two separated piezoelectric media

The coupling of surface acoustic waves propagating in two separated piezoelectric media is studied using the perturbation theory of Auld. The results of the analysis are applied to two configurations using Bi12GeO20 and CdS crystals. It is found that the loss due to coupling is about 7 dB at 50 MHz in the cases of (111)-cut, [110]-prop. Bi12GeO20 and Y-cut, 60°-X prop. CdS combination. On étudie le couplage des ondes acoustiques de surface se propageant sur deux milieux piezo-eléctriques par la théorie de perturbation de Auld. Les resultats d'analyse sont appliqué's aux deux configurations des cristanx Bi12GeO20 et CdS. On trouve que la perte par couplage est environ de 7 dB a 50 MHz dans le cas de combination de (111)-coupe, [110]-prop. Bi12GeO20 et Y-coupe, 60°-X prop. CdS.

Confirmation of pauling's theory that vitamin C improves immunity to infection

It is pointed out that the complement Clq, associated with the immune response system, has a part containing about 80 residues with a collagen-like sequence, with Gly at every third location and having also a number of Hyp and Hyl residues in locations before Gly, and that it takes the triple-helical conformation characteristic of collagen. As with collagen biosynthesis, ascorbic acid is therefore expected to be required for its production. Also, collagen itself, in the extracellular matrix, is connected with the fibroblast surface protein (FSP), whose absence leads to cell proliferation, and whose addition leads to suppression of malignancy in tissue culture. All these show the great importance of vitamin C for resistance to diseases, and even to cancer, as has been widely advocated by Pauling.

A Comprehensive Theory of Erosive Burning in Solid Rocket Propeilants

The theory of erosive burning has been constructed front first principles using turbulent boundary layer concepts. It is shown that the problem constitutes one of solution of flame propagation equation for turbulent flow. The final approximate solution for the case of single step overall kinetics reveals the combined effects of fluid mechanics and chemical kinetics. The results obtained from this theory are compared with earlier experimental results. The dependence of erosive burning characteristics on various parameters has been elucidated.

Topological defects in crystals: A density-wave theory

A new approach for describing dislocations and other topological defects in crystals, based on the density wave theory of Ramakrishnan and Yussouff is presented. Quantitative calculations are discussed in brief for the order parameter profiles, the atomic configuration and the free energy of a screw dislocation with Burgers vector b = (a/2, a/2,a/2 ) in a bcc solid. Our results for the free energy of the dislocation in a crystal of sizeR, when expressed as (λb 2/4π) ln (αR/|b|) whereλ is the shear elastic constant, yield, for example, the valueα ⋍ 1·85 for sodium at its freezing temperature (371°K). The density distribution in the presence of the dislocation shows that the dislocation core has a columnar character. To our knowledge, this study represents the first calculation of dislocation structure, including the core, within the framework of an order parameter theory incorporating thermal effects.