435 research outputs found
Modern Feynman Diagrammatic One-Loop Calculations
In this talk we present techniques for calculating one-loop amplitudes for
multi-leg processes using Feynman diagrammatic methods in a semi-algebraic
context. Our approach combines the advantages of the different methods allowing
for a fast evaluation of the amplitude while monitoring the numerical stability
of the calculation. In phase space regions close to singular kinematics we use
a method avoiding spurious Gram determinants in the calculation. As an
application of our approach we report on the status of the calculation of the
amplitude for the process .Comment: 10 pages, 2 figures; contribution to the proceedings of the CPP2010
Workshop, 23-25 Sep. 2010, KEK, Tsukuba, Japa
Thermal Conductivity of Pure Silica MEL and MFI Zeolite Thin Films
This paper reports the room temperature cross-plane thermal conductivity of pure silica zeolite (PSZ) MEL and MFI thin films. PSZ MEL thin films were prepared by spin coating a suspension of MEL nanoparticles in 1-butanol solution onto silicon substrates followed by calcination and vapor-phase silylation with trimethylchlorosilane. The mass fraction of nanoparticles within the suspension varied from 16% to 55%. This was achieved by varying the crystallization time of the suspension. The thin films consisted of crystalline MEL nanoparticles embedded in a nonuniform and highly porous silica matrix. They featured porosity, relative crystallinity, and MEL nanoparticles size ranging from 40% to 59%, 23% to 47% and 55 nm to 80 nm, respectively. PSZ MFI thin films were made by in situ crystallization, were b-oriented, fully crystalline, and had a 33% porosity. Thermal conductivity of these PSZ thin films was measured at room temperature using the 3ω method. The cross-plane thermal conductivity of the MEL thin films remained nearly unchanged around 1.02±0.10 W m−1 K−1 despite increases in (i) relative crystallinity, (ii) MEL nanoparticle size, and (iii) yield caused by longer nanoparticle crystallization time. Indeed, the effects of these parameters on the thermal conductivity were compensated by the simultaneous increase in porosity. PSZ MFI thin films were found to have similar thermal conductivity as MEL thin films even though they had smaller porosity. Finally, the average thermal conductivity of the PSZ films was three to five times larger than that reported for amorphous sol-gel mesoporous silica thin films with similar porosity and dielectric constant
An open reproducible framework for the study of the iterated prisoner's dilemma
The Axelrod library is an open source Python package that allows for
reproducible game theoretic research into the Iterated Prisoner's Dilemma. This
area of research began in the 1980s but suffers from a lack of documentation
and test code. The goal of the library is to provide such a resource, with
facilities for the design of new strategies and interactions between them, as
well as conducting tournaments and ecological simulations for populations of
strategies.
With a growing collection of 139 strategies, the library is a also a platform
for an original tournament that, in itself, is of interest to the game
theoretic community. This paper describes the Iterated Prisoner's Dilemma, the
Axelrod library and its development, and insights gained from some novel
research.Comment: 11 pages, Journal of Open Research Software 4.1 (2016
Tumor-infiltrating lymphocytes: Streamlining a complex manufacturing process
Adoptive cell therapy of tumor-infiltrating lymphocytes has shown promise for treatment of refractory melanoma and other solid malignancies; however, challenges to manufacturing have limited its widespread use. Traditional manufacturing efforts were lengthy, cumbersome and used open culture systems. We describe changes in testing and manufacturing that decreased the process cycle time, enhanced the robustness of critical quality attribute testing and facilitated a functionally closed system. These changes have enabled export of the manufacturing process to support multi-center clinical trials
Murine Pancreatic Adenocarcinoma Dampens SHIP-1 Expression and Alters MDSC Homeostasis and Function
Pancreatic cancer is one of the most aggressive cancers, with tumor-induced myeloid-derived suppressor cells (MDSC) contributing to its pathogenesis and ineffective therapies. In response to cytokine/chemokine receptor activation, src homology 2 domain-containing inositol 5'-phosphatase-1 (SHIP-1) influences phosphatidylinositol-3-kinase (PI3K) signaling events, which regulate immunohomeostasis. We hypothesize that factors from murine pancreatic cancer cells cause the down-regulation of SHIP-1 expression, which may potentially contribute to MDSC expansion, and the suppression of CD8(+) T cell immune responses. Therefore, we sought to determine the role of SHIP-1 in solid tumor progression, such as murine pancreatic cancer.Immunocompetent C57BL/6 mice were inoculated with either murine Panc02 cells (tumor-bearing [TB] mice) or Phosphate Buffer Saline (PBS) (control mice). Cytometric Bead Array (CBA) analysis of supernatants of cultured Panc02 detected pro-inflammatory cytokines such as IL-6, IL-10 and MCP-1. TB mice showed a significant increase in serum levels of pro-inflammatory factors IL-6 and MCP-1 measured by CBA. qRT-PCR and Western blot analyses revealed the in vivo down-regulation of SHIP-1 expression in splenocytes from TB mice. Western blot analyses also detected reduced SHIP-1 activity, increased AKT-1 and BAD hyper-phosphorylation and up-regulation of BCL-2 expression in splenocytes from TB mice. In vitro, qRT-PCR and Western blot analyses detected reduced SHIP-1 mRNA and protein expression in control splenocytes co-cultured with Panc02 cells. Flow cytometry results showed significant expansion of MDSC in peripheral blood and splenocytes from TB mice. AutoMACS sorted TB MDSC exhibited hyper-phosphorylation of AKT-1 and over-expression of BCL-2 detected by western blot analysis. TB MDSC significantly suppressed antigen-specific CD8(+) T cell immune responses in vitro.SHIP-1 may regulate immune development that impacts MDSC expansion and function, contributing to pancreatic tumor progression. Thus, SHIP-1 can be a potential therapeutic target to help restore immunohomeostasis and improve therapeutic responses in patients with pancreatic cancer
An algebraic/numerical formalism for one-loop multi-leg amplitudes
We present a formalism for the calculation of multi-particle one-loop
amplitudes, valid for an arbitrary number N of external legs, and for massive
as well as massless particles. A new method for the tensor reduction is
suggested which naturally isolates infrared divergences by construction. We
prove that for N>4, higher dimensional integrals can be avoided. We derive many
useful relations which allow for algebraic simplifications of one-loop
amplitudes. We introduce a form factor representation of tensor integrals which
contains no inverse Gram determinants by choosing a convenient set of basis
integrals. For the evaluation of these basis integrals we propose two methods:
An evaluation based on the analytical representation, which is fast and
accurate away from exceptional kinematical configurations, and a robust
numerical one, based on multi-dimensional contour deformation. The formalism
can be implemented straightforwardly into a computer program to calculate
next-to-leading order corrections to multi-particle processes in a largely
automated way.Comment: 71 pages, 7 figures, formulas for rank 6 pentagons added in Appendix
Recent Progress in the Golem Project
We report on the current status of the Golem project which aims at the
construction of a general one-loop evaluator for matrix elements. We construct
the one-loop matrix elements from Feynman diagrams in a highly automated way
and provide a library for the reduction and numerically stable evaluation of
the tensor integrals involved in this approach. Furthermore, we present
applications to physics processes relevant for the LHC.Comment: 7 pages, 4 figures, contrib. to proceedings of "Loops and Legs in
Quantum Field Theory", 10th DESY Workshop on Elementary Particle Theory,
25-30 April 2010, Woerlitz, German
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