One-loop unitarity of scalar field theories on Poincare invariant commutative nonassociative spacetimes

We study scalar field theories on Poincare invariant commutative nonassociative spacetimes. We compute the one-loop self-energy diagrams in the ordinary path integral quantization scheme with Feynman's prescription, and find that the Cutkosky rule is satisfied. This property is in contrast with that of noncommutative field theory, since it is known that noncommutative field theory with space/time noncommutativity violates unitarity in the above standard scheme, and the quantization procedure will necessarily become complicated to obtain a sensible Poincare invariant noncommutative field theory. We point out a peculiar feature of the non-locality in our nonassociative field theories, which may explain the property of the unitarity distinct from noncommutative field theories. Thus commutative nonassociative field theories seem to contain physically interesting field theories on deformed spacetimes.Comment: 25 pages, 9 figures ; appendix and references adde

Chiral gravity in higher dimensions

We construct a chiral theory of gravity in 7 and 8 dimensions, which are equivalent to Einstein-Cartan theory using less variables. In these dimensions, we can construct such higher dimensional chiral gravity because of the existence of gravitational instanton. The octonionic-valued variables in the theory represent the deviation from the gravitational instanton, and from their non-associativity, prevents the theory to be SO(n) gauge invariant. Still the chiral gravity holds G_2 (7-D), and Spin(7) (8-D) gauge symmetry.Comment: 18 pages, no figures. Minor typos corrected. Updated reference

Errors in CGAP xProfiler and cDNA DGED: the importance of library parsing and gene selection algorithms

<p>Abstract</p> <p>Background</p> <p>The Cancer Genome Anatomy Project (CGAP) xProfiler and cDNA Digital Gene Expression Displayer (DGED) have been made available to the scientific community over a decade ago and since then were used widely to find genes which are differentially expressed between cancer and normal tissues. The tissue types are usually chosen according to the ontology hierarchy developed by NCBI. The xProfiler uses an internally available flat file database to determine the presence or absence of genes in the chosen libraries, while cDNA DGED uses the publicly available UniGene Expression and Gene relational databases to count the sequences found for each gene in the presented libraries.</p> <p>Results</p> <p>We discovered that the CGAP approach often includes libraries from dependent or irrelevant tissues (one third of libraries were incorrect on average, with some tissue searches no correct libraries being selected at all). We also discovered that the CGAP approach reported genes from outside the selected libraries and may omit genes found within the libraries. Other errors include the incorrect estimation of the significance values and inaccurate settings for the library size cut-off values. We advocated a revised approach to finding libraries associated with tissues. In doing so, libraries from dependent or irrelevant tissues do not get included in the final library pool. We also revised the method for determining the presence or absence of a gene by searching the UniGene relational database, revised calculation of statistical significance and sorted the library cut-off filter.</p> <p>Conclusion</p> <p>Our results justify re-evaluation of all previously reported results where NCBI CGAP expression data and tools were used.</p

Vascular endothelial growth factor in children with neuroblastoma: a retrospective analysis

BACKGROUND: Despite aggressive therapy, advanced stage neuroblastoma patients have poor survival rates. Although angiogenesis correlates with advanced tumour stage and plays an important role in determining the tumour response to treatment in general, clinical data are still insufficient, and more clinical evaluations are needed to draw conclusions. The aim of this study was to evaluate vascular endothelial growth factor (VEGF) expression in patients with neuroblastoma, determine whether it correlates with other prognostic factors and/or therapeutic response, and to assess should VEGF be considered in a routine diagnostic workup. ----- MATERIALS AND METHODS: VEGF expression was determined by immunohistochemistry using anti-VEGF antibody in paraffin embedded primary tumour tissue from 56 neuroblastoma patients. Semiquantitative expression of VEGF was estimated and compared with gender, age, histology, disease stage, therapy, and survival. Statistical analyses, including multivariate analysis, were performed. ----- RESULTS: VEGF expression correlated with disease stage and survival in neuroblastoma patients. Combination of VEGF expression and disease stage as a single prognostic value for survival (P-value = 0.0034; odds ratio (OR) (95%CI) = 26.17 (2.97-230.27) exhibited greater correlation with survival than individually. Hematopoietic stem cell transplantation significantly improved survival of the advanced stage patients with high VEGF expression. ----- CONCLUSION: VEGF expression should be considered in a routine diagnostic workup of children with neuroblastoma, especially in those more than 18 months old and with advanced disease stage. High VEGF expression at the time of disease diagnosis is a bad risk prognostic factor, and can be used to characterize subsets of patients with an unfavourable outcome

Crystal Growth and Characterization of New Laser Crystal Bi_4Si_3O_<12> : Nd

The Bridgman growth of Nd doped BSO single crystals and their optical and laser properties are investigated. Good quality crystals were grown with Nd concentration varying from 0.5 to 5.0at%. Uniformity of Nd distribution in the crystals has been characterized by determining the absorption coefficient at different stages of crystallization. It has been found that the absorption coefficients at the peak wavelengths of 743 and 809nm were 34 and 19cm^, respectively, for 5.0 at% Nd doping. The distribution coefficient, k, of Nd in BSO was also determined by means of chemical analysis and it was found to be about 1.1. Fluorescence lifetime measurement was carried out and the lifetime of fluorescence intensity, τ_0 was calculated to be 267.7μs. Thermal conductivity of the grown crystals as a function of Nd concentration has also been measured.The Bridgman growth of Nd doped BSO single crystals and their optical and laser properties are investigated. Good quality crystals were grown with Nd concentration varying from 0.5 to 5.0at%. Uniformity of Nd distribution in the crystals has been characterized by determining the absorption coefficient at different stages of crystallization. It has been found that the absorption coefficients at the peak wavelengths of 743 and 809nm were 34 and 19cm^, respectively, for 5.0 at% Nd doping. The distribution coefficient, k, of Nd in BSO was also determined by means of chemical analysis and it was found to be about 1.1. Fluorescence lifetime measurement was carried out and the lifetime of fluorescence intensity, τ_0 was calculated to be 267.7μs. Thermal conductivity of the grown crystals as a function of Nd concentration has also been measured

Lateral hopping of CO on Cu(111) induced by femtosecond laser pulses

We present a theoretical study of the lateral hopping of a single CO molecule on Cu (111) induced by femtosecond laser pulses by Mehlhorn et al. [Phys. Rev. Lett. 104, 076101 (2010)]. Our model assumes an intermode coupling between the CO frustrated translation (FT) and frustrated rotation (FR) modes with a weak and strong electronic friction coupling to hot electrons, respectively, and heat transfer between the FT mode and the substrate phonons. In this model the effective electronic friction coupling of the FT mode depends on the absorbed laser fluence F through the temperature of the FR mode. The calculated hopping yield as a function of F nicely reproduces the nonlinear increase observed above F=4.0 J/m(2). It is found that the electronic heating via friction coupling nor the phonon coupling alone cannot explain the experimental result. Both heatings are cooperatively responsible for CO hopping on Cu (111). The electronic heat transfer dominates over the phononic one at high F, where the effective electronic friction coupling becomes larger than the phononic coupling

Lateral hopping of CO molecules on Pt(111) surface by femtosecond laser pulses

Theory of heat transfer between adsorbate vibrational degrees of freedom and ultrafast laser heated hot electrons including vibrational intermode coupling is applied to calculate two-pulse correlation, laser fluence dependence and time dependence of lateral hopping of CO molecules from a step to terrace site on a stepped Pt (111) surface. The intermode coupling is a key ingredient to describe vibrational heating of the frustrated translation mode responsible for the CO hopping. The calculated results are in good agreement with the experimental results, especially if we scale down the experimentally determined absorbed fluence. It is found that CO hopping is induced by indirect heating of the FT mode by the FR mode with a strong frictional coupling to hot electrons