The Limits of Special Relativity

The Special Theory of Relativity and the Theory of the Electron have had an interesting history together. Originally the electron was studied in a non relativistic context and this opened up the interesting possibility that lead to the conclusion that the mass of the electron could be thought of entirely in electromagnetic terms without introducing inertial considerations. However the application of Special Relativity lead to several problems, both for an extended electron and the point electron. These inconsistencies have, contrary to popular belief not been resolved satisfactorily today, even within the context of Quantum Theory. Nevertheless these and subsequent studies bring out the interesting result that Special Relativity breaks down within the Compton scale or when the Compton scale is not neglected. This again runs contrary to an uncritical notion that Special Relativity is valid for point particles.Comment: 13 pages,Te

Exact solution of a 2D interacting fermion model

We study an exactly solvable quantum field theory (QFT) model describing interacting fermions in 2+1 dimensions. This model is motivated by physical arguments suggesting that it provides an effective description of spinless fermions on a square lattice with local hopping and density-density interactions if, close to half filling, the system develops a partial energy gap. The necessary regularization of the QFT model is based on this proposed relation to lattice fermions. We use bosonization methods to diagonalize the Hamiltonian and to compute all correlation functions. We also discuss how, after appropriate multiplicative renormalizations, all short- and long distance cutoffs can be removed. In particular, we prove that the renormalized two-point functions have algebraic decay with non-trivial exponents depending on the interaction strengths, which is a hallmark of Luttinger-liquid behavior.Comment: 59 pages, 3 figures, v2: further references added; additional subsections elaborating mathematical details; additional appendix with details on the relation to lattice fermion

Monopoles and clusters

We define and study certain hyperkaehler manifolds which capture the asymptotic behaviour of the SU(2)-monopole metric in regions where monopoles break down into monopoles of lower charges. The rate at which these new metrics approximate the monopole metric is exponential, as for the Gibbons-Manton metric.Comment: v2.: relation to calorons mentioned; added explanation

A 2D Luttinger model

A detailed derivation of a two dimensional (2D) low energy effective model for spinless fermions on a square lattice with local interactions is given. This derivation utilizes a particular continuum limit that is justified by physical arguments. It is shown that the effective model thus obtained can be treated by exact bosonization methods. It is also discussed how this effective model can be used to obtain physical information about the corresponding lattice fermion system.Comment: 36 pages, 3 figures; v2: 36 pages, 2 figures, minor corrections; v3: 38 pages, 2 figures, clarifications and minor corrections, adapted to follow-up paper arXiv:0907.127

Analysis of transcription factors key for mouse pancreatic development establishes NKX2-2 and MNX1 mutations as causes of neonatal diabetes in man

notes: PMCID: PMC3887257This is a freely-available open access publication. Please cite the published version which is available via the DOI link in this record.Understanding transcriptional regulation of pancreatic development is required to advance current efforts in developing beta cell replacement therapies for patients with diabetes. Current knowledge of key transcriptional regulators has predominantly come from mouse studies, with rare, naturally occurring mutations establishing their relevance in man. This study used a combination of homozygosity analysis and Sanger sequencing in 37 consanguineous patients with permanent neonatal diabetes to search for homozygous mutations in 29 transcription factor genes important for murine pancreatic development. We identified homozygous mutations in 7 different genes in 11 unrelated patients and show that NKX2-2 and MNX1 are etiological genes for neonatal diabetes, thus confirming their key role in development of the human pancreas. The similar phenotype of the patients with recessive mutations and mice with inactivation of a transcription factor gene support there being common steps critical for pancreatic development and validate the use of rodent models for beta cell development.Wellcome TrustDiabetes UKEuropean Community’s Seventh Framework Programme (FP7/2007-2013

Magneto-optical disk as a CD-ROM development tool

Computer-based training (CBT) programs are becoming more sophisticated. They are no longer electronic papers, but are large multi-media systems which incorporate computer-generated graphics and digital audio as well as text. The numerous computer-generated graphics, large audio files, and complex hypertext structures place a great demand on the computer system's binary storage capacity (disk space). If the use of interactive video is prohibitive because of cost or other restraints, a compact disk read-only memory (CD-ROM) delivery system is a viable delivery system. Because CD-ROM is a read-only system, the development and delivery system must be different. There are several alternatives for the development system, including a very large hard-disk and a magneto-optical disk drive. Recently a CBT package for radiation protection workers (RPT's) that was developed at Los Alamos National Laboratory (LANL) was delivered on CD-ROM. A magneto-optical drive was used for the development system. This paper will discuss some reasons for selecting a CD-ROM delivery system and the use of magneto-optical disk drive as the development system