The KLN Theorem and Soft Radiation in Gauge Theories: Abelian Case

We present a covariant formulation of the Kinoshita, Lee, Nauenberg (KLN) theorem for processes involving the radiation of soft particles. The role of the disconnected diagrams is explored and a rearrangement of the perturbation theory is performed such that the purely disconnected diagrams are factored out. The remaining effect of the disconnected diagrams results in a simple modification of the usual Feynman rules for the S-matrix elements. As an application, we show that when combined with the Low theorem, this leads to a proof of the absense of the $1/Q$ corrections to inclusive processes (like the Drell-Yan process). In this paper the abelian case is discussed to all orders in the coupling.Comment: 27 pages, LaTeX, 14 figure

Gauge-Independent Off-Shell Fermion Self-Energies at Two Loops: The Cases of QED and QCD

We use the pinch technique formalism to construct the gauge-independent off-shell two-loop fermion self-energy, both for Abelian (QED) and non-Abelian (QCD) gauge theories. The new key observation is that all contributions originating from the longitudinal parts of gauge boson propagators, by virtue of the elementary tree-level Ward identities they trigger, give rise to effective vertices, which do not exist in the original Lagrangian; all such vertices cancel diagrammatically inside physical quantities, such as current correlation functions or S-matrix elements. We present two different, but complementary derivations: First, we explicitly track down the aforementioned cancellations inside two-loop diagrams, resorting to nothing more than basic algebraic manipulations. Second, we present an absorptive derivation, exploiting the unitarity of the S-matrix, and the Ward identities imposed on tree-level and one-loop physical amplitudes by gauge invariance, in the case of QED, or by the underlying Becchi-Rouet-Stora symmetry, in the case of QCD. The propagator-like sub-amplitude defined by means of this latter construction corresponds precisely to the imaginary parts of the effective self-energy obtained in the former case; the real part may be obtained from a (twice subtracted) dispersion relation. As in the one-loop case, the final two-loop fermion self-energy constructed using either method coincides with the conventional fermion self-energy computed in the Feynman gauge.Comment: 30 pages; uses axodraw (axodraw.sty included in the src); final version to appear in Phys. Rev.

Inhibition of Multidrug Resistance by SV40 Pseudovirion Delivery of an Antigene Peptide Nucleic Acid (PNA) in Cultured Cells

Peptide nucleic acid (PNA) is known to bind with extraordinarily high affinity and sequence-specificity to complementary nucleic acid sequences and can be used to suppress gene expression. However, effective delivery into cells is a major obstacle to the development of PNA for gene therapy applications. Here, we present a novel method for the in vitro delivery of antigene PNA to cells. By using a nucleocapsid protein derived from Simian virus 40, we have been able to package PNA into pseudovirions, facilitating the delivery of the packaged PNA into cells. We demonstrate that this system can be used effectively to suppress gene expression associated with multidrug resistance in cancer cells, as shown by RT-PCR, flow cytometry, Western blotting, and cell viability under chemotherapy. The combination of PNA with the SV40-based delivery system is a method for suppressing a gene of interest that could be broadly applied to numerous targets

Newly Developed Mg2+–Selective Fluorescent Probe Enables Visualization of Mg2+ Dynamics in Mitochondria

Mg2+ plays important roles in numerous cellular functions. Mitochondria take part in intracellular Mg2+ regulation and the Mg2+ concentration in mitochondria affects the synthesis of ATP. However, there are few methods to observe Mg2+ in mitochondria in intact cells. Here, we have developed a novel Mg2+–selective fluorescent probe, KMG-301, that is functional in mitochondria. This probe changes its fluorescence properties solely depending on the Mg2+ concentration in mitochondria under physiologically normal conditions. Simultaneous measurements using this probe together with a probe for cytosolic Mg2+, KMG-104, enabled us to compare the dynamics of Mg2+ in the cytosol and in mitochondria. With this method, carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP)–induced Mg2+ mobilization from mitochondria to the cytosol was visualized. Although a FCCP–induced decrease in the Mg2+ concentration in mitochondria and an increase in the cytosol were observed both in differentiated PC12 cells and in hippocampal neurons, the time-courses of concentration changes varied with cell type. Moreover, the relationship between mitochondrial Mg2+ and Parkinson's disease was analyzed in a cellular model of Parkinson's disease by using the 1-methyl-4-phenylpyridinium ion (MPP+). A gradual decrease in the Mg2+ concentration in mitochondria was observed in response to MPP+ in differentiated PC12 cells. These results indicate that KMG-301 is useful for investigating Mg2+ dynamics in mitochondria. All animal procedures to obtain neurons from Wistar rats were approved by the ethical committee of Keio University (permit number is 09106-(1))

A structured approach for the assessment of internal dose: The IDEAS guidelines

The need for harmonisation of the procedures for internal dose assessment has been recognised within an EU research project under the 5th Framework Programme. The aim of the IDEAS project was to develop general guidelines for standardising assessments of intakes and internal doses. It started in October 2001 and ended in June 2005. The project is closely related to some goals of the work of Committee 2 of the International Commission on Radiological Protection and since 2003 there has been close co-operation between the two groups. The general philosophy of the guidelines is focusing on the principles of harmonisation, accuracy and proportionality. The proposed system of 'level of task' to structure the approach of internal dose evaluation is also reported. Some details of the internal structure of the guidelines for the different pathways of intake are provided. © The Author 2007. Published by Oxford University Press. All rights reserved

Application of IDEAS guidelines: The IDEAS/IAEA intercomparison exercise on internal dose assessment

As part of the EU Fifth Framework Programme IDEAS project 'General Guidelines for the Evaluation of Incorporation Monitoring Data', and in collaboration with the International Atomic Energy Agency, a new intercomparison exercise for the assessment of doses from intakes of radionuclides was organised. Several cases were selected, to cover a wide range of practices in the nuclear fuel cycle and medical applications. The cases were: (1) acute intake of HTO, (2) acute inhalation of the fission products 137Cs and 90Sr, (3) acute inhalation of 60Co, (4) repeated intakes of 131I, (5) intake of enriched uranium and (6) single intake of Pu isotopes and 241Am. This intercomparison exercise especially focused on the effect of the Guidelines proposed by the IDEAS project for harmonisation of internal dosimetry. © The Author 2007. Published by Oxford University Press. All rights reserved

General guidelines for the assessment of internal dose from monitoring data (project IDEAS) [Guide pratique pour estimer la dose interne à partir des résultats de mesure de surveillance (projet IDEAS)]

In recent major international intercomparison exercises on intake and internal dose assessments from monitoring data, the results calculated by different participants varied significantly. This was mainly due to the broad variety of methods and assumptions applied in the assessment procedure. Based on these experiences the need for harmonisation of the procedures has been formulated within an EU research project under the 5th Framework Programme. The aim of the project, IDEAS, is to develop general guidelines for standardising assessments of intakes and internal doses. The IDEAS project started in October 2001 and will end in March 2005. Eight institutions from seven European countries are participating. Inputs from internal dosimetry professionals from across Europe are also being used to ensure a broad consensus in the outcome of the project. The IDEAS project is closely related to some goals of the work of committee 2 of the ICRP and since 2003 there has been close cooperation between the two groups. To ensure that the guidelines are applicable to a wide range of practical situations, the first step has been to compile a database of well-documented cases of internal contamination. In parallel, an improved version of an existing software package has been developed and distributed to the partners for further use. A large number of cases from the database have been evaluated independently by partners in the project using the same software and the results have been reviewed. Based on these evaluations, guidelines are being drafted and will be discussed with dosimetry professionals from around the world by means of a virtual workshop on the Internet early in 2004. The guidelines will be revised and refined on the basis of the experiences and discussions of this virtual workshop and the outcome of an intercomparison exercise organised as part of the project. This will be open to all internal dosimetry professionals. © 2005 EDP Sciences