bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of myostatin F94L on carcass yield in cattle
Authors: Sellick G. S. , Pitchford W. S. , Morris C. A. , Cullen N. G. , Crawford A. M. , Raadsma H. W. , Bottema C. D. K.
Published: July 2007

In this study, a highly significant quantitative trait locus (QTL) for meat percentage, eye muscle area (EMA) and silverside percentage was found on cattle chromosome 2 at 0–15 cM, a region containing the positional candidate gene growth differentiation factor 8 (GDF8), which has the common alias myostatin (MSTN). Loss‐of‐function mutations in the MSTN gene are known to cause an extreme ‘double muscling’ phenotype in cattle. In this study, highly significant associations of MSTN with cattle carcass traits were found using maternally inherited MSTN haplotypes from outbred Limousin and Jersey cattle in a linkage disequilibrium analysis. A previously reported transversion in MSTN (AF320998.1:g.433C>A), resulting in the amino acid substitution of phenylalanine by leucine at position 94 of the protein sequence (F94L), was the only polymorphism consistently related to increased muscling. Overall, the size of the g.433C>A additive effect on carcass traits was moderately large, with the g.433A allele found to be associated with a 5.5% increase in silverside percentage and EMA and a 2.3% increase in total meat percentage relative to the g.433C allele. The phenotypic effects of the g.433A allele were partially recessive. This study provides strong evidence that a MSTN genotype can produce an intermediate, non‐double muscling phenotype, which should be of significant value for beef cattle producers.
HLA‐DQB1*0602 allele is associated with splenomegaly in Japanese sarcoidosis
Authors: Sato H. , Nagai S. , Du Bois R. M. , Handa T. , Suginoshita Y. , Ohta K. , Welsh K. I. , Izumi T.
Published: July 2007

Objectives.  The association between HLA class II alleles and susceptibility to sarcoidosis is well documented. Further, the HLA‐DRB1*15 and DQB1*0602 haplotype has been considered as a marker for both chronic and severe disease. Splenomegaly has been proposed as a marker for severity and activity in sarcoidosis, although its functional mechanism is unknown. In other diseases, HLA class II alleles can be markers for splenomegaly. We therefore set out to test the hypothesis that the primary DRB1*15‐DQB1*0602 link in sarcoidosis would be to splenomegaly.

Design and subjects.  We performed abdominal ultrasonography to evaluate the prevalence and extent of splenomegaly and genotyped for HLA‐DRB1 and DQB1 using allele or allele group specific primers in polymerase‐chain‐reaction on 138 Japanese sarcoidosis patients as case comparison study. Furthermore, we explored their relationship with other clinically important indices, e.g. chest radiograph stage, serum angiotensin‐converting enzyme (ACE) concentration and duration of disease.

Results.  Splenomegaly was detected in 37 (26.8%) sarcoidosis patients. DQB1*0602 showed associations with splenomegaly (P < 0.0001) and longer disease duration (P = 0.007). In addition, higher chest radiograph staging was associated with both DQB1*0602 (P = 0.02) and splenomegaly (P = 0.003). The presence of splenomegaly was associated with higher serum ACE concentration (P < 0.0001).

Conclusion.  We conclude that in the Japanese population the primary association of HLA class II DQB1*0602 is with splenomegaly. This allele is also a marker for chronicity and lung disease severity. On the other hand, the presence of splenomegaly is a marker for severity and activity. Further studies are needed to explore the relationship between splenomegaly and sarcoidosis in other ethnic groups and its association with HLA‐DQB1*0602.
Homogeneous TiB2 Ceramics Achieved by Electric Current‐Assisted Self‐Propagating Reaction Sintering
Authors: Salamon David , Eriksson Mirva , Nygren Mats , Shen Zhijian
Published: July 2007

Using spark plasma sintering techniques, homogeneous microstructures of titanium diboride (TiB2) ceramics were obtained by sintering of boron and titanium powder mixtures. The results show that an additional electric current is essential for achieving a large number of evenly distributed ignition points that ensure that the self‐propagating reaction simultaneously takes place within the entire volume. The effects of the electric current, the use of Mg additions, and the heating rates on the resulting TiB2 ceramic densities and microstructures are discussed.
Human S100A15 splice variants are differentially expressed in inflammatory skin diseases and regulated through Th1 cytokines and calcium
Authors: Wolf Ronald , Lewerenz Virginia , Büchau Amanda S. , Walz Markus , Ruzicka Thomas
Published: July 2007

Abstract:  The human calcium‐binding protein (hS100A15) was first identified in inflamed hyperplastic psoriatic skin, where the S100A15 gene is transcribed into two mRNA splice variants, hS100A15‐S and hS100A15‐L. To compare the contribution of the human S100A15 (hS100A15) isoforms in skin inflammation and differentiation, we determined the expression, distribution and regulation of hS100A15‐S and hS100A15‐L in psoriasis and chronic atopic eczema compared with normal skin. We found that both hS100A15 transcripts were mainly distributed in the epidermis of normal and inflamed skin with hS100A15‐L being the predominantly expressed mRNA isoform in both psoriasis and atopic eczema. In cultured keratinocytes, IL‐1β and Th1 cytokines significantly induced hS100A15‐L compared with hS100A15‐S. In contrast, Th2‐derived cytokines had no influence on the expression of either hS100A15 splice variant. Differentiation of human keratinocytes induced by 1.2 mm calcium resulted in the upregulation of both hS100A15 mRNA isoforms. Our data show that both hS100A15 splice variants are differentially regulated and expressed with epidermal differentiation and skin inflammation. Overexpression of hS100A15 in chronic inflammatory skin diseases and regulation by inflammatory cytokines and calcium suggest that hS100A15 is involved in Th1‐associated epithelial responses and epidermal maturation in normal and diseased human skin.
Prediction, diagnosis, and causal thinking in forecasting
Authors: Einhorn Hillel J. , Hogarth Robin M.
Published: July 2007

While forecasting involves forward/predictive thinking, it depends crucially on prior diagnosis for suggesting a model of the phenomenon, for defining‘relevant’variables, and for evaluating forecast accuracy via the model. The nature of diagnostic thinking is examined with respect to these activities. We first consider the difficulties of evaluating forecast accuracy without a causal model of what generates outcomes. We then discuss the development of models by considering how attention is directed to variables via analogy and metaphor as well as by what is unusual or abnormal. The causal relevance of variables is then assessed by reference to probabilistic signs called‘cues to causality’. These are: temporal order, constant conjunction, contiguity in time and space, number of alternative explanations, similarity, predictive validity, and robustness. The probabilistic nature of the cues is emphasized by discussing the concept of spurious correlation and how causation does not necessarily imply correlation. Implications for improving forecasting are considered with respect to the above issues.
The functioning of large‐scale cooperative enterprise in the south: A case study from Nicaragua
Authors: Wiggins Steve
Published: July 2007

This paper examines the functioning and performance of a large cooperative federation in Nicaragua, concerned mainly with retailing. Set up in late 1985, in response to undersupply to smallholders, especially those in the mountainous interior, it has followed a strategy of rapid expansion. By using a federal structure which has allowed middle and junior management freedom to take the initiative, and by adopting mostly simple, appropriate, and non‐bureaucratic procedures, the federation has succeeded in mounting an impressively large operation, with over 190 shops selling a wide variety of goods. On the other hand, at the centre, sales have grown sluggishly since 1988, costs have risen, and liquidity has become a problem. Moreover, the organization has lost capital, largely through its pricing policy. These can be blamed partly on the federated structure, the lack of a medium‐term strategy, and dependency upon external donors; and partly on the trading environment of recession and uncertainty. The case study illustrates the difficulties in establishing large‐scale cooperative enterprise, and the need in the long run to realise comparative advantage.
Of cattle, farmers, veterinarians and the World Bank: The political economy of veterinary services privatization in Cameroun
Authors: Gros Jean‐Germain
Published: July 2007

This article relates how the World Bank makes reform decisions in a particular economic sector and country. It highlights some of the key issues pertaining to the privatization of livestock veterinary services in sub‐Saharan Africa, with a particular focus on Cameroun. Relating to the economics literature, it argues that veterinary services have both public and private good attributes. Therefore, any policy aimed at privatizing the entire spectrum of services without regard to their public good character is likely to result in significant market failures. With empirical evidence provided by Cameroun, the article also demonstrates that the ‘privatization project’ advocated most strongly by key international lending institutions does not enjoy much support among African policy makers. It also raises issues of implementation in policy environments fraught with bureaucratic indifference and resistance, as well as divisions within the lending community over policy directions.
Municipal institutional strengthening and donor coordination: The case of Ecuador
Authors: Fuhr Harald
Published: July 2007

This article analyses the circumstances surrounding municipal institutional reforms in Ecuador which were set in motion through, on the one hand, a link established by external contributors between the financing of infrastructure projects at the local level, and institutional reforms on the other. Credit was only provided to municipalities on the understanding that attempts were made by them to improve their capacity to provide urban services. This approach has enjoyed considerable success to date.
Adjusting policy‐thinking to global pragmatics and future problematics
Authors: Angelides Christodoulis , Caiden Gerald
Published: July 2007

An unprecedented rate of change is rapidly outdating traditional modes of policy thinking. New orientations are needed to deal with the growing interaction between global pragmatics which encompass emerging trends that diverge radically from anything previously experienced and intractable problems that do not respond to conventional solutions and future problematics which arise from the nature of the future and paradoxes underlying futures oriented thinking. Current policy thinking suffers from many incapacities and should give way to the search for a new holistic paradigm based on the twin propositions that the properties of the parts can only be understood through an understanding of the dynamics of the whole and that the dynamics of the whole may be greater than the summation of the parts. Several suggestions are made where to make a start. The new policy thinking must provide a common meaning, purpose and sense of direction. It must be anticipatory, considering both the probable and the improbable, looking both backwards and forwards. It must be crisis‐prepared, innovative, multi‐dimensional and capable of handling adversity, uncertainty, and complexity. Other components of governance must also be improved lest an oversized head develop on an undersized body. Meantime, hope is placed in a new type of learning that would allow for living with past mistakes and failures without being overwhelmed, one that would allow for change, perception, problem reformulation, unlearning and even debunking. It would involve questioning the appropriateness of ultimate purposes and goals, selecting new replacements, and identifying new means for achieving them.
Making social science research applicable: The case of agricultural extension research in Egypt
Authors: Honadle B. W.
Published: July 2007

One problem in the management of agricultural research is the integration of research and extension. The links between research and extension are tenuous for many reasons, including institutional and administrative factors that thwart collaboration; geographic isolation of extension staff; differences in status, prestige and educational attainment between extension workers and researchers; and motivational issues impeding stronger ties between extension and research personnel. This article argues that the problem with much research intended for extension audiences is that it is supply driven and not demand driven. Using a social science research unit within the Agricultural Research Center of the Egyptian Ministry of Agriculture as a case study, this article analyses the research produced by the unit and assesses its potential usefulness for extension. It then attempts to show why it does not reach this potential. Among the reasons are that the researchers lack experience and background in rural issues and agricultural extension; research results lag behind extension's need for the information; and there is no plan to disseminate the results to the extension community after research is completed. The article offers some suggestions for overcoming such barriers, including involving extension in the design of research projects and holding seminars on research results after projects are completed; changing the incentives for researchers to do more applied research; and diversifying the methods and disciplines used to conduct the research.
Einige Anwendungsmöglichkeiten der Monte‐Carlo‐Methode
Authors: Crone Irene
Published: July 2007

Einleitung. ‐ I. Diffusion thermischer Neutronen durch ein mittelschweres Element. ‐ II. Zwei einfache parabolische Differentialgleichungen. ‐ III. Allgemeine DIRICHLETsche Probleme. ‐ IV. Elliptische Eigenwertprobleme. ‐ V. Matrixinversion. ‐ Schlußbemerkung.
Optische Eigenschaften der Metalle
Authors: Ginsburg W. L. , Motulewitsch G. P.
Published: July 2007

Einleitung. ‐ § 1. Reflektion des Lichts an einer Metalloberfläche ‐ § 2. Oberflächenimpedanz und effektive komplexe Dielektrizitätskonstante des Metalls ‐ § 3. Mikrotheorie im Fall des normalen Skineffekts. ‐ § 4. Mikrotheorie im Fall des anomalen Skineffekts. a) Grundlagen der Theorie des anomalen Skineffekts. b) Ergebnisse für das ultrarote Spektralgebiet. c) Berücksichtigung der Quanteneffekte ‐ § 5. Methoden zur Messung von neff χeff und A ‐ § 6. Diskussion der vorhandenen experimentellen Daten ‐ Schluß ‐ Literaturverzeichnis.
SU (3) Symmetry Scheme, A Review
Authors: London Georges W.
Published: July 2007

This review is intended for non‐experts (experimentalists, students, etc.) as an introduction to the applications of group theory to strong interactions. It contains no new results nor is it a complete survey of the field. The analogy, both formal and philosophical, with isospin invariance and charge independence is emphasized. The paper briefly reviews the elements of group theory and then, as an example, discusses the isospin group. Rank two groups in general, SU (3) in particular, are then discussed. The connection to physics is made through the identification of the basis vectors of the different group representations with physical states. i.e. particles. The concept of U‐spin is introduced to derive some dynamic predictions of the model. The violation of SU (3) invariance is then discussed. The mass formulae, relating the medium‐strong and electromagnetic splittings within a multiplet, are derived to first order. The extension of SU (3) symmetry to weak interactions is briefly discussed.
Dirac Formalism for Arbitrary Spin in S‐Matrix Theory
Authors: Enflo B. O. , Laurent B. E.
Published: July 2007

The S‐matrix formalism is built up from the beginning, for particles with and without mass, through systematic use of the representation Ds,0 D0,s of the homogeneous Lorentz group. Only concepts referring to space and time are considered. Within the framework of the formalism, the close interdependence between CPT, spin and statistics, crossing symmetry and unitarity is explicitly emphasized. The concepts of intrinsic parity, spin‐flip and particle conjugation are re‐examined. A comparison is made with conventional field‐theoretic formalism.
An Unitarized Model of Quasi‐Two‐Body Contributions to Single Pion Production by Mesons
Authors: Baracca A. , Bergia S.
Published: July 2007

A general formulation is presented of resonant final state interactions (isobars) in single pion production by mesons with particular reference to the N* case.

An essential use is made of the separation of the process into the quasi‐two‐body production and the decay steps. This allows the insertion of the isobar hypothesis into a scheme capable of dealing correctly with the spin‐angular momentum aspects.

A general scheme is developed for the exploitment of the two‐channel unitarity conditions in a partial wave analysis of the isobar production amplitudes.

The method for computing normalized distributions is finally outlined.
Algebraic Geometry and Feynman Amplitudes
Authors: Cunningham John
Published: July 2007

The representation method of obtaining first and second type Landau curves from the Landau criteria is described. The Plucker characteristic analysis of singular curves is outlined and its relationship with the theory of automorphic functions indicated. A differential approach to singularity classification is discussed and a possible extension of the method to obtain asymptotic behaviour is conjectured.

A preliminary form of some of the material here presented was the basis of a lecture given by the author at the University of Wales Colloquium in Applied Mathematics, Gregynog, 1969.
Spectra and Distributions in a Unitarized Model of Quasi‐Two‐Body Contributions to Single Pion Production by Mesons
Authors: Baracca A. , Bergia S. , Bramon A. , de Santis Y. , Gomis J. , Montoto A. , Monzoni V.
Published: July 2007

We study the general properties of single pion production processes in boson‐nucleon collisions in the hypothesis that any couple of the final particles may undergo a resonant final state interaction.

The aim is to supply the experimentalists with a tool apt to interpret Dalitz‐plots and distributions as they stand, as an alternative to the normal method of selecting samples of events to study one particular quasi‐two‐body process.

General expressions of spectra and distributions are obtained.
Theoretische Untersuchungen zur Asymmetrie der Pionphotoproduktion mit einem polarisierten Target
Authors: Kramer G.
Published: July 2007

The theoretical importance of experiments with polarised targets for pion photoproduction at high energies is discussed.

In an introductory chapter the basic formulas and simple Regge pole models are introduced in connection with elastic pion‐proton scattering. The relevance of Regge‐cut models is considered in connection with pion‐charge‐exchange scattering. In the main part we write down formulas for the polarisation parameters in terms of the helicity amplitudes for pion photoproduction. Then we concentrate on the target asymmetry A for photoproduction of neutral and charged pions. Several models with Regge poles and Regge cuts generated by absorption are presented and discussed concerning the results forA. In the last part we report a fit to π± photoproduction data and give predictions of A for γp → π+n and γn → π−p.
Methods of Quantum Field Theory with Rapidly Increasing Spectral Functions
Authors: Volkov M. K.
Published: July 2007

A review of the methods of constructing the scattering amplitudes and Green functions in the non‐renormalizable quantum field theories with rapidly increasing spectral functions is given. Such theories as the theories with the chiral Lagrangians, those which describe the interactions with gravitational fields and the theories of weak interactions can be taken as examples. Three big groups of these methods are presented here. In particular, these are as follows: construction of the scattering amplitude in x‐space (the function F(x)), construction of the scattering amplitude in momentum space (the function F˜ (p)) and definition of the scattering amplitudes by solving the appropriate equations (in x‐ or p‐Space).

This works was reported at the Second International Symposium on Non‐local Quantum Field Theory in 1970 at Azau, USSR.
Comparison of Various K̄N Partial Wave Analyses in the Region 0–1400 MeV/c
Authors: Gupta Madan L. , Arndt R. A. , Roper L. David
Published: July 2007

A comprehensive comparative study of the available K̄N partial wave analyses is made with a view to bring out their similarities and disagreements and to point towards those momentum regions that require particular attention in all future analyses. The multichannel nature of the K̄N scattering is discussed along with the presently available scattering cross‐section data for various channels. The parametrization of the various partial wave analyses is discussed and their amplitudes calculated and compared under the set of conventions proposed by Levi Setti.
Single Particle Distributions from Veneziano Amplitudes II
Authors: Bebel D. , Biebl K. J. , Ebert D. , Otto H. J.
Published: July 2007

The x‐ and p⟂2‐dependence of the distribution function for the inclusive reaction A + B → C + anything has been investigated for some typical cases using the dual six point function in the tree approximation as a model for T33. It is found that the form the x‐distribution depends critically on the trajectory intercepts in the AC̄ and BC̄ channels, respectively. The p⟂2‐dependence is nearly exponential for large x. For small x‐values a steeper behaviour in the small p⟂2 region is obtained which is especially pronounced for small masses of the observed particles. Diagrams with twists contributing to the distribution function for inclusive reactions with neutral pions lead to oscillations and dips near the nonsense wrong signature points of the AC̄ and BC̄ channel trajectories.
Some Approximations in the Theorie of Moments and Transitions for Even‐Odd Nuclei
Authors: Weigel M.
Published: July 2007

In the framework of Green's functions, the theory of moments and transitions for even‐odd‐nuclei is developed. It is shown, how these quantities are connected with the effective particle‐hole force and the generalized linear response function for the neighbour even‐even nuclei. The response function describes the change of the single‐particle propagator due to an external perturbation. For superfluid systems the Nambu [1] – Engelsberg [2] – Belyaev [3] technique has been used. The connection between earlier treatments is established, especially with the semiphenomenological approach of Migdal [4] and co‐workers. Some approximations for the relevant effective particle‐hole force emerging from the many‐body theory are discussed in detail. Furthermore the generalization of the RPA‐approximation for the auto‐correlation function of density fluctuations in the case of superfluidity is given.
Invariant Spinors and their Use for Expansions of Scattering Amplitudes
Authors: Enflo B. O. , Laurent B. E.
Published: July 2007

A general covariant scheme is proposed for the kinematical analysis of arbitrary reactions. By this scheme the problem of finding invariant amplitudes and corresponding kinematical covariants can be solved systematically. The amplitudes are labelled by two invariant indices for each particle related to spin and parity. The method provides a tool for exploiting the symmetries of the M‐function, including crossing symmetry and the Pauli principle. Amplitudes free from kinematical singularities can easily be constructed.
A Re‐Examination of the Arguments for Baryon Parity Doublets
Authors: Enflo B. O.
Published: July 2007

The arguments for baryon parity doubling are re‐examined by use of a spin formalism developed by the author together with B. E. LAURENT. It is shown that the transformation between good parity amplitudes and helicity flip and non‐flip amplitudes in πN scattering is ambiguous. It is further shown that the unitary condition for boson‐fermion scattering gives no information of the parity of intermediate states contributing to a good parity amplitude. These ambiguities follow from the fact that for boson‐fermion scattering the CPT transformation of an amplitude does not commute with the projection on a definite parity. It is finally shown how a Regge pole model with linear trajectories without parity doubling can be constructed without any specific dynamical assumptions or artifices. The constraints on the residues needed in this case do not violate any general principles.
Algebraic Methods in Ordinary Quantum Mechanics Revisited
Authors: Ghirardi Gian Carlo
Published: July 2007

We reconsider the problem of giving an algebraic treatment to quantum problems within the framework of ordinary quantum mechanics. After a concise review of the irreducible representations of the relevant Lie algebra, we formulate the general scheme within which all previous approaches can be easily fitted. We then show which are the explicit connexions between this general scheme and the specific approaches found in the literature. The whole paper constitutes a concise and synthetic summary of algebraic techniques in ordinary quantum mechanics.
Bhabha Equations for Unique Mass and Spin
Authors: Santhanam T. S. , Tekumalla A. R.
Published: July 2007

Linear relativistic wave equations of Bhabha's type are discussed. Conditions for unique mass and unique spin are analysed in detail. It is shown that if one relaxes the diagonalisability of βo by a weaker block form one gets a class of equations describing a spin‐half particle. Several algebras which emerge and their representations are studied. The existence or otherwise of the hermitianising matrix in such cases is explicitly discussed. The properties of the new equations in the presence of minimally coupled electro‐magnetic field are discussed.
Effective Range Expansion for Electron‐Neutrino and Electron‐Antineutrino Scattering
Authors: Kramer G.
Published: July 2007

Weak interactions from a pure S‐matrix point of view are considered in order to get an idea about the high‐energy behaviour. To have the weak interaction as undisturbed as possible by electromagnetic and strong interactions we study only the leptonic processes eν → νe, eν → νe and eē → νν. We calculate the corresponding partial wave amplitudes for s and p waves and constrain them by low energy behaviour coming from the lowest order approximation, analyticity and unitarity. Several examples of partial wave cross sections for the three reactions with resonant behaviour in the eν or eν channel are calculated numerically.
Zerfallende Zustände als physikalisch nichtisolierbare Teilsysteme
Authors: Szász Gy. I.
Published: July 2007

Presently the investigations of decaying quantum mechanical systems lack a well‐founded concept, which is reflected by several formal difficulties of the corresponding mathematical treatment. In order to clarify in some respect the situation, we investigate, within the framework of nonrelativistic quantum mechanics, the resonant scattering of an initially well localized partial wave packet ϕl(r, t). If the potential decreases sufficiently fast for r → ∞, ϕl(r, t) can be expressed at sufficiently long time after the scattering has taken place, as ϕl(r, t) = I(r, t) + ∑ Niϕl(Ki, r) exp {–iKi2 t/2M} × Θ(ki – γi – Mr/t), ϕl(Ki, r) being the resonant solution with complex “momentum” Ki = ki – iγi. From this heuristic relation one can deduce not only the probability for the creation of unstable particles but also obtain some hints to a connection between decaying states and physically nonisolable partial systems. On the other hand, this connection can perhaps display the inadequacy of attempts which suggest to solve the problem of decaying states within the usual Hilbert space methods.
Regge Models and Dispersion Relations for Partial Waves
Authors: Kaschluhnxs F. , Müller‐Preussker M.
Published: July 2007

The asymptotic behaviour of partial wave amplitudes is calculated supposing various Regge models for the total scattering amplitude A(s, t, u). The high energy partial wave behaviour obtained is combined with the validity of partial wave dispersion relations. It is shown that consistency of these assumptions can only be achieved by demanding.

1) a definite asymptotic behaviour of the discontinuity of the left hand cut of partial wave amplitudes.

2) the validity of partial wave sum rules of similar kind as the well‐known finite energy sum rules for the total amplitude.

All steps of the derivation shall first be demonstrated for elastic scattering of identical scalar particles. Then within the helicity formalism the results are generalized for particles with arbitrary spin and different masses. Finally the question is studied whether the sum rules can be employed to determine unknown CDD‐pole parameters in an N/D approach for the I = J = 1/2 state in πN scattering. It is shown that the sum rules of highest order are able to do that.
Pseudoscalar Mesons as Goldstone Bosons in Chiral SU(4) ⊗ SU(4) Symmetry
Authors: Bose S. K.
Published: July 2007

We study the pseudoscalar mesons in the framework of broken chiral SU(4) SU(4) symmetry when the symmetry‐breaking Hamiltonian, HSB, is taken as –(u0 + cu8 + du15) and the symmetry of the Hamiltonian is realized in Goldstone‐Nambu way. An interesting property of two chimeral SU(4) subgroups and the Goldstone nature of some of the pseudoscalar mesons in certain symmetry limits are exploited to obtain some mass relations and the ratio c/d.
Quantum Theory of Path‐Dependent Field Operator Based on Characteristics of Displacement Operators
Authors: Okabayashi Takao
Published: July 2007

The path‐dependent operator formalism of quantum electrodynamics proposed by Mandelstam is reformulated through quantum field theory based on characteristics of displacement operators in Minkowski space. It is shown that total energy‐ and total angular‐momentum operators can generate inhomogeneous Lorentz transformations on any local operator including path‐independent bilinear forms constructed of path‐dependent electron operator Ψ(x, P), but that generators for Ψ(x, P) itself are only their Ψ(x, P)‐dependent parts. Such an unfamiliar feature is characteristic of the path‐dependent operator formalism. The present approach possesses unique merits in making the logic of the formalism transparent as described in the following: i) Quantum electrodynamics can be formulated but for the help of potential operator even as a tool for calculation up to a final step. ii) Some restriction, which can be used to discuss propriety of gauge conditions, can be figured out. iii) By introducing a path‐rearrangement operator, we can keep infinite variety of space‐like pathes with the same end point throughout our formulation as they stand. iv) Several points which must be modified in the presence of magnetic monopole are closed up.
Duality Properties of Virtual Compton Amplitudes
Authors: Jersák J.
Published: July 2007

The duality hypothesis based on the light cone behaviour of the current commutator is applied to the nonforward Compton amplitudes and the restrictions which the duality imposes on these amplitudes in various high energy limits are reviewed. It is shown how the duality of the Compton amplitudes can be tested experimentally in deep inelastic annihilation and exclusive electroproduction of mesons. A dual pole model of the Compton amplitude is constructed.
Parametrische Instabilitäten in Plasmen
Authors: Spatschek K. H.
Published: July 2007

Linear and nonlinear theoretical aspects of parametric instabilities in plasmas are reviewed. Applications in laser‐fusion and heating of toroidally confined plasmas are considered. We start with the electrostatic decay and modulational instabilities in homogeneous, unmagnetized plasmas. The basic equations are derived in a physically simple manner. Electromagnetic modes are included using a wave description for the scattering instabilities (Raman and Brillouin scattering). Kinetic limits where quasi‐modes are involved (Compton scattering) and the corresponding instabilities in magnetic plasmas are discussed. Using a WKB‐analysis the effects of density, temperature, and expansion velocity gradients as well as turbulence, finite laser bandwidth, boundaries, and oblique incidence are estimated. The calculations are extended to include such phenomena as sidescattering and decay near the quartercritical and critical density where the WKB approximation breaks down. Nonlinear saturation mechanisms are discussed for Raman, Brillouin, decay, and modulational instabilities. Special attention is given to pump depletion and particle trapping. The existence of solitary waves and the stability of the latter are investigated. The conclusions are compared with results of experiments as well as computer simulations.
Consequences of Crossed Channel Structure for High Energy Elastic Scattering
Authors: Haan Oswald
Published: July 2007

This review describes a field in the S‐matrix theory of elastic stattering. Analyticity and elastic unitarity in the crossed t‐channel are shown in a rigorous manner to yield constraints on s‐channel quantities. Strong restrictions on s‐channel partial wave with angular momenta l ⩾√s/2(b0 + λ In s) follow from realistic assumptions on the amplitude in the unphysical domain (Mandelstam analyticity and Regge behaviour). The possibility of phenomenological application of these results is discussed.
The Algebraic Structure of the Thirring Model
Authors: Heck Lydia
Published: July 2007

We summarize the representation theory of the group SU(1,1) as needed for the massless Thirring model. Representations of the current operator algebra are given taking account of conformal covariance. The conformal covariance transformation behaviour of the Thirring field is investigated. The Haag‐Araki‐Kastler observable algebra of the Thirring field is reconstructed from the Wightman theory of this model.
Einstein‐Maxwell Equations: Gauge Formulation and Solutions for Radiating Bodies
Authors: Carmeli Moshe , Kaye Michael
Published: July 2007

The subject of the SL(2, c) gauge theory of gravitation is reviewed. A detailed discussion is given on the differential geometry and the fibre bundle structure of such a theory. The coupling of Maxwell's field equations to those of gravitation is also given. The field equations obtained, which are shown to be equivalent to the coupled Einstein‐Maxwell equations, are subsequently solved. The solutions sought after are radiating type ones of the kind of the Kerr metric, but with the mass of the body being variable and is a function of the retarded time. A generalization of the Kerr metric is presented and its energy‐momentum tensor is analyzed in detail. The classification of the field obtained according to the Petrov scheme is also given.
Nonlocal Quark Model and Meson Decays
Authors: Dubničková A. Z. , Efimov G. V. , Ivanov M. A.
Published: July 2007

In the framework of nonlocal quantum field theory we have constructed a quantized field called the virton field satisfying the conditions:

the field of free virton quanta is equal identically to zero

the causal function of this virton field differs from zero.

We consider this virton field can be a good candidate for the description of quark confinement.

It is suggested that the physical particles are described by the ordinary quantized fields but they interact with each other through the quark‐virton field only. Using the simplest form of the interaction Lagrangian invariant under transformations of the SU(3) × SUc(3) × U1 group, the mass corrections, some strong, weak and electromagnetic decays of the vector and pseudoscalar mesons are considered. A good agreement with experiment is obtained.
Polarization Phenomena in Elastic Electron‐Proton Scattering
Authors: Kobayashi Masaaki
Published: July 2007

A unified treatment is given by using the scattering matrix in the Pauli spin spaces and polarization density matrices. Various quantities such as polarization P, asymmetry A, spin correlation parameters Cαβ, double polarization asymmetry Aαβ, polarization transfer parameters Dt, At, Rt and depolarization and spin rotation parameters D, A, R are expressed in terms of six coefficients which appear in the scattering matrix. Some explicit expressions as well as numerical results for these quantities are also given in the one photon exchange approximation.
Space‐Time Approach to the Description of Cumulative‐Type Processes
Authors: Kalinkin B. N. , Cherbu A. V. , Shmonin V. L.
Published: July 2007

An approach to the description of cumulative‐like processes is developed. It explicitly uses space‐time factors determining the development of these processes and some general features of hadronic inclusive spectra. The results are compared with all the available experimental data. The predictions testable in current and planned experiments are given.
Problems of Deep Inelastic Lepton‐Nucleus Interaction
Authors: Darbaidze Ya. Z. , Esakia S. M. , Garsevanishvili V. R. , Menteshashvili Z. R.
Published: July 2007

The deep inelastic scattering of electrons (muons) and neutrinos on the nuclei and the process of lepton pair production in hadron‐nucleus collisions are considered. The expressions for the corresponding differential cross‐sections are derived provided the final lepton and the spectator fragment of the initial nucleus are detected in coincidence. The structure functions of the processes under consideration are analysed by the principle of automodelity. Some scale‐invariant regularities are established for them. In the framework of “light front” formalism for many‐body systems the relations of these structure functions to the usual structure functions of the deep inelastic lepton hadron interaction are obtained. A hypothesis is put forward on the scale invariance of structure functions with respect to the ξ‐variable which is some complicated dimensionless combination of kinematic invariants.
The Gribov Process: Soft Parton Interactions in So‐Called Reggeon Field Theory
Authors: Grassberger P.
Published: July 2007

As shown in previous papers, Reggeon “Field” Theory is actually a Markov process describing the evolution of wee partons during a boost. In the present paper, the physical interpretation of scattering amplitudes and cross sections is discussed, both for the uncut (unlabelled) and cut (labelled) version. Elastic amplitudes and total cross sections, inclusive cross sections, fully diffractive events, and inelastic diffraction are all shown to have simple interpretations in the parton model. Finally, the connection with models for evolution of hard partons in QCD is discussed.
Gamma Ray Astronomy and the Origin of Cosmic Rays
Authors: Schlickeiser Reinhard
Published: July 2007

The classical production processes for high energy gamma radiation in the interstellar medium are discussed and confronted with recent satellite observations. It is shown that gamma ray data in their present form do not provide definite conclusions on the origin of cosmic rays. Some current ideas on the nature of gamma ray point sources are presented.
Quantum Chromodynamics and Parity‐Violating Nucleon‐Nucleon‐Pion Coupling
Authors: Galić Harvoje , Guberina Branko , Tadić Dubravko
Published: July 2007

Parity‐violating (PV) nucleon‐nucleon‐pion (NNπ) coupling is studied in order to extract information about nonleptonic weak processes in general. The connection between the PV NNπ amplitude and PV nonleptonic hyperon decays is explored in detail. An outline of the historical background is given. It is shown how the PV NNπ amplitude is to be calculated starting from the Weinberg‐Salam model for weak interactions. The effective weak Hamiltonian for PV nonleptonic processes is derived in detail, introducing quantum chromodynamics and flavor‐symmetry breaking. The role of the so‐called penguin terms is clarified. The PV NNπ amplitude is calculated using current algebra, chiral invariance, and quark models (e.g. the MIT bag model) for the description of baryons. It is emphasized that certain techniques used in the description of nonleptonic decays can undergo an independent test via the study of PV NNπ amplitudes. These amplitudes can be experimentally explored in experiments on nuclear parity violation. A discussion of nuclear calculations and experiments is also included.
Perturbation Theory, Level‐Splitting and Large‐Order Behaviour
Authors: Müller‐Kirsten H. J. W.
Published: July 2007

The level‐splitting of asymptotically degenerate eigenvalues, their discontinuity across a cut and the large‐order behaviour of the perturbation expansion are usually difficult to calculate. In the following we review some methods of calculation with particular emphasis on the periodic potential in order to exhibit the relationship between all three quantities.
Phenomenology of Elastic Hadron Diffraction
Authors: Jenkovszky L. L.
Published: July 2007

Recent experimental data on high‐energy elastic scattering of hadrons is reviewed in the light of various theoretical models with special emphasize on the dipole (or geometrical) Pomeron. As suggested by its name, this model combines the properties of two different approaches: the analytic and geometric ones. Its virtue is simplicity, which makes possible analytic calculation of many complicated problems.
What happened to the system perspective in reliability?
Authors: Halverson M. , Ozdes D.
Published: July 2007

This paper takes a broad overview of the reliability and safety engineering practice as it is commonly exercised in the aerospace and military industries today, especially with respect to complex electronic equipment which typically includes considerable software content. A general deficiency is noted with regard to the system‐level approach to reliability. It would appear that the system‐level reliability activities are given less attention than is needed, while excessive emphasis is placed on component micro‐physics, component failure models, and various component‐oriented analyses. Systems‐level reliability topics, which predominate in the equipment reliability which is actually observed, are sometimes ignored by reliability engineers.

Methods and practical philosophies to re‐establish a solid system engineering foundation for contemporary reliability practice, which have been developed through the authors' experience in the field, are presented. Finally, an example analysis is shown to illustrate the concepts.
Quality and reliability assessment of hardware and software during the total product life cycle
Authors: Jones David R. , Murthy Vyasaraj , Blanchard Jeffrey
Published: July 2007

A major challenge for the computer industry is the need for the development and implementation of an engineering languge which provides continuous linkages and measurement between the customer and all engineering functions internal to the company. Such a language would allow information solution developers and information service providers to be able to continuously monitor the quality and reliability performance of integrated hardware and software products during the complete product life cycle. A quantitative engineering language needs to be developed to provide seamless and continuous linkages between the customer—the user of integrated computer systems—and all of the engineering development and manufacturing functions tasked with designing and building solutions which meet customer needs. A methodology is proposed which addresses this challenge by the implementation of two metrics: total defects per unit (TDU) and the annual rate of events (ARE). These two metrics can measure all hardware, software and computer integration events during the total product life cycle. A methodology is presented which provides a rigorous translation of the ARE metric, monitored at the customer site, into the traditional reliability metrics used by engineering and manufacturing. Algorithms are presented which directly translate AREs into mean time between failures (MTBF), mean time between parts replacement (MTBPR) and mean time between system interruptions (MTBSI). The ARE metric meets the customer requirement of being able to clearly focus on the reliability and availability performance of total systems as a result of hardware and software components, the user interface, and environmental factors. The paper discusses the development and application of integrated TDU and ARE metrics and shows how the total product life cycle quality and reliability of a complex integrated computer and communications solution can be efficiently monitored and managed for improvement during design, manufacturing, and installation performance in an integrated customer environment.
Bite and unconfirmed failures
Authors: Rees R. A.
Published: July 2007

Electronic BITE is poor at identifying hardware failure and in present design approaches tends to create the reviled ‘unconfirmed failure’. A different approach to BITE and unconfirmed failure could improve both operational performance and the cost of maintenance.
Simulation strategies to identify the failure parameters of repairable systems under the influence of general repair
Authors: Love C. E. , Guo R.
Published: July 2007

With repairable systems, it is suspected than many of the post‐failure repairs have the effect of partially resetting the failure rate of the system. Consequently, identifying the correct failure model and its associated parameters is confounded by the impact of these repair effects. The purpose of this paper is to compare the use of several simulation strategies involving mimicking experiments, to assist in this identification process. Data collected from a hydrelectric turbine unit is used to illustrate the approach.
Lifetime test evaluation with mathcad®: Automated weibull parameter and plotting point estimate with arbitrary confidence interval and graphics
Authors: Accumolli Alberto , Sjöberg Sven
Published: July 2007

This application note describes a computer‐based method for automated evaluation of Weibull‐distributed life‐time data. It uses comercially available software, MathCad, to set up equations and graphs. The computer application is a simple and non‐expensive way of evaluating and displaying your life‐time data taking into consideration both parametric and non‐parametric confidence intervals. It is valid for arbitrarily censored data.
Modelling rail vehicle brake pad wearout and replacement
Authors: Bohoris G. A. , Desai A. , Edge D. J.
Published: July 2007

Inspections of rail vehicle multiple units are scheduled in British Rail mainly subject to the recommended interval between inspections of brake pads. This paper presents the development of a model of brake pad wear based on regression analysis and its subsequent use in the consideration of replacement and inspection strategies. The current scrapping size of 11 mm on motor vehicles proved to be too high for it was possible to extend pad life by as much as a third by reducing the scrapping size to 7 mm. On trailer vehicles it was found that the current scrapping size of 6 mm was satisfactory.