CPT symmetry and antimatter gravity in general relativity

The gravitational behavior of antimatter is still unknown. While we may be confident that antimatter is self-attractive, the interaction between matter and antimatter might be either attractive or repulsive. We investigate this issue on theoretical grounds. Starting from the CPT invariance of physical laws, we transform matter into antimatter in the equations of both electrodynamics and gravitation. In the former case, the result is the well-known change of sign of the electric charge. In the latter, we find that the gravitational interaction between matter and antimatter is a mutual repulsion, i.e. antigravity appears as a prediction of general relativity when CPT is applied. This result supports cosmological models attempting to explain the Universe accelerated expansion in terms of a matter-antimatter repulsive interaction.Comment: 6 pages, to be published in EPL (http://epljournal.edpsciences.org/

Construction of Non-Perturbative, Unitary Particle-Antiparticle Amplitudes for Finite Particle Number Scattering Formalisms

Starting from a unitary, Lorentz invariant two-particle scattering amplitude , we show how to use an identification and replacement process to construct a unique, unitary particle-antiparticle amplitude. This process differs from conventional on-shell Mandelstam s,t,u crossing in that the input and constructed amplitudes can be off-diagonal and off-energy shell. Further, amplitudes are constructed using the invariant parameters which are appropriate to use as driving terms in the multi-particle, multichannel non-perturbative, cluster decomposable, relativistic scattering equations of the Faddeev-type integral equations recently presented by Alfred, Kwizera, Lindesay and Noyes. It is therefore anticipated that when so employed, the resulting multi-channel solutions will also be unitary. The process preserves the usual particle-antiparticle symmetries. To illustrate this process, we construct a J=0 scattering length model chosen for simplicity. We also exhibit a class of physical models which contain a finite quantum mass parameter and are Lorentz invariant. These are constructed to reduce in the appropriate limits, and with the proper choice of value and sign of the interaction parameter, to the asymptotic solution of the non-relativistic Coulomb problem, including the forward scattering singularity, the essential singularity in the phase, and the Bohr bound-state spectrum

PCR based approaches to the identification and classification of Leishmania

Random amplified polymorphic DNA (RAPD) was tested for the identification and classification of Leishmania. RAPD was found to be useful for the identification of species of L. (Leishmania) and L. (Yiannia) and for the classification of L. (Yiannia) species. The polymerase chain reaction (PCR) was tested for the identification of Leishmania from mammals and lizards, using both published primers and new primers which amplify kinetoplast minicircle DNA. The size of the PCR product was found to be useful for discriminating between some sympatric pairs of species such as L. braziliensis and L. mexicana. Isotopically labelled probes prepared from the variable region of the kinetoplast minicircle were tested for specificity for the identification of New and Old World species of Leishmania. The specificity was dependent on the concentration of target DNA and was manipulated to investigate relationships between Leishmania species. Restriction digests of kinetoplast DNA (schizodemes) prepared by PCR and by centrifugation through 20% sucrose were compared for the identification of strains of L. infantum and L. chagasi. Twenty three strains of L. chagasi from cases of visceral and cutaneous leishmaniasis in Honduras were examined by RAPD, schizodemes, differential display, isoenzyrnes, RFLPs and PFGE to discover whether genetic differences existed between parasites causing the two different pathologies. The parasites were found to be unusually homogeneous and no differences were found which correlated with pathology by any of these methods. Restriction digests of PCR amplified small subunit ribosomal DNA (SSU rDNA) (ribodemes) were tested to find markers specific for the genus Leishmania. A classification of the Leishmania based on the restriction fragments indicated that L. hertigi and L. herreri were more closely related to Endotrypanum than to Leishmania, and that the lizard Leishmania could not be placed in separate genus from the Leishmania. Ribodemes were used to identify two strains of parasites supplied by colleagues in Central America that could not be identified by existing methods for the identification of Leishmania. One of these strains appeared to be identical to a C. luciliae reference strain. The other strain produced a fingerprint unlike any of the available reference strains. A variable region of the SSU rRNA gene was identified that was suitable for classifying trypanosomatids and the sequence of this region was used to classify the strain that could not be identified by fingerprinting

Scale in education research: towards a multi-scale methodology

This article explores some theoretical and methodological problems concerned with scale in education research through a critique of a recent mixed-method project. The project was framed by scale metaphors drawn from the physical and earth sciences and I consider how recent thinking around scale, for example in ecosystems and human geography might offer helpful points and angles of view on the challenges of thinking spatially in education research. Working between the spatial metaphors of ecology scholars and the critiques of the human geographers, for example the hypercomplex social space in Lefebvre’s political-economic thinking and the fluid, simultaneous, multiple spatialities of Massey’s post-structuralism, I problematize space and scale in education research. Interweaving these geographical ideas with Giddens’ structuration and Bourdieu’s theory of practice, both of which employed what might be termed scale-bridging to challenge social science’s entrenched paradigms, leads me to reconsider what is possible and desirable in the study of education systems. Following the spatial turn in the social sciences generally, there is an outstanding need to theorise multi-scale methodology for education research

Exploring social patterns of participation in university-entrance level mathematics in England

In recent years in England there has been considerable attention given to a range of apparent crises in mathematics education, one of which has been the long term decline of participation in university-entrance level (Advanced or A) mathematics. Given the negative impact upon mathematics participation of Curriculum 2000, together with the government’s emphasis on Science Technology Engineering and Mathematics (STEM) subjects, the political intent to increase participation in Advanced level mathematics is clear. This paper uses the National Pupil Database (NPD) to develop a descriptive statistical account of how completion of Advanced level mathematics varies along the social axes of SES, ethnicity and gender. The process of working with the NPD is discussed in some depth in order to clarify the processes involved in this type of quantitative analysis and to illustrate how this analysis can be used to raise questions about who is doing what mathematics in the post-16 age-range

Three-neutron resonance trajectories for realistic interaction models

Three-neutron resonances are investigated using realistic nucleon-nucleon interaction models. The resonance pole trajectories are explored by first adding an additional interaction to artificially bind the three-neutron system and then gradually removing it. The pole positions for the three-neutron states up to J=5/2 are localized in the third energy quadrant-Im (E)<=0, Re (E)<=0-well before the additional interaction is removed. Our study shows that realistic nucleon-nucleon interaction models exclude any possible experimental signature of three-neutron resonances.Comment: 13 pages ; 8 figs ; 5 table

S-wave eta'-proton FSI; phenomenological analysis of near-threshold production of pi0, eta, and eta' mesons in proton-proton collisions

We describe a novel technique for comparing total cross sections for the reactions pp --> pp pi(0), pp --> pp eta, and pp --> pp eta' close to threshold. The initial and final state proton-proton interactions are factored out of the total cross section, and the dependence of this reduced cross section on the volume of phase space is discussed. Different models of the proton-proton interaction are compared. We argue that the scattering length of the S-wave eta'-proton interaction is of the order of 0.1 fm.Comment: 10 pages, 5 figure