Search results for "vector"
showing 10 items of 2660 documents
The Chiral Anomaly
1989
The Dirac operator on a manifold M is a first order partial differential operator acting on sections of a spin bundle over M. The Dirac operator is elliptic when the metric of M is positive definite. The main task in this chapter is to study properties of the determinant of the Dirac operator.
Form factors of the isovector scalar current and the ηπ scattering phase shifts
2015
33 pages.- 14 figures.- v2: Some clarifications and corrections of typos
The Sea Urchin sns5 Insulator Protects Retroviral Vectors From Chromosomal Position Effects by Maintaining Active Chromatin Structure
2009
Silencing and position-effect (PE) variegation (PEV), which is due to integration of viral vectors in heterochromatin regions, are considered significant obstacles to obtaining a consistent level of transgene expression in gene therapy. The inclusion of chromatin insulators into vectors has been proposed to counteract this position-dependent variegation of transgene expression. Here, we show that the sea urchin chromatin insulator, sns5, protects a recombinant gamma-retroviral vector from the negative influence of chromatin in erythroid milieu. This element increases the probability of vector expression at different chromosomal integration sites, which reduces both silencing and PEV. By chr…
RIP-Chip analysis supports different roles for AGO2 and GW182 proteins in recruiting and processing microRNA targets.
2019
Background MicroRNAs (miRNAs) are small non-coding RNA molecules mediating the translational repression and degradation of target mRNAs in the cell. Mature miRNAs are used as a template by the RNA-induced silencing complex (RISC) to recognize the complementary mRNAs to be regulated. To discern further RISC functions, we analyzed the activities of two RISC proteins, AGO2 and GW182, in the MCF-7 human breast cancer cell line. Methods We performed three RIP-Chip experiments using either anti-AGO2 or anti-GW182 antibodies and compiled a data set made up of the miRNA and mRNA expression profiles of three samples for each experiment. Specifically, we analyzed the input sample, the immunoprecipita…
Characterization of chromatographic peaks using the linearly modified Gaussian model. Comparison with the bi-Gaussian and the Foley and Dorsey approa…
2017
To characterize column performance in liquid chromatography, several parameters must be obtained from experimental data. These parameters can be computed through the numerical integration of the net signal to calculate the moments after subtraction of the baseline. This requires the establishment of the peak integration limits. The whole process introduces significant uncertainty. For this reason, several alternative procedures have been proposed to measure the area, mean time and variance, based on the assumption that the chromatographic peak can be described with a mathematical function. This allows the calculation of the peak position and variance making use of the values of the experime…
Program for the interpretive optimization of two-dimensional resolution.
2016
The challenge of fully optimizing LC × LC separations is horrendous. Yet, it is essential to address this challenge if sophisticated LC × LC instruments are to be utilized to their full potential in an efficient manner. Currently, lengthy method development is a major obstacle to the proliferation of the technique, especially in industry. A program was developed for the rigorous optimization of LC × LC separations, using gradient-elution in both dimensions. The program establishes two linear retention models (one for each dimension) based on just two LC × LC experiments. It predicts LC × LC chromatograms using a simple van-Deemter model to generalize band-broadening. Various objectives (ana…
Musical pitch quantization as an eigenvalue problem
2020
How can discrete pitches and chords emerge from the continuum of sound? Using a quantum cognition model of tonal music, we prove that the associated Schrödinger equation in Fourier space is invariant under continuous pitch transpositions. However, this symmetry is broken in the case of transpositions of chords, entailing a discrete cyclic group as transposition symmetry. Our research relates quantum mechanics with music and is consistent with music theory and seminal insights by Hermann von Helmholtz.
Incidence and epidemiology of Citrus tristeza virus in the Valencian Community of Spain
2000
Abstract The first outbreak of citrus tristeza disease in Spain caused by Citrus tristeza virus (CTV) was recorded in 1957 in the Valencian Community (VC). In total c. 40 million trees, mainly of sweet orange and mandarin grafted on sour orange rootstocks, declined due to CTV. Large-scale surveys in different municipalities of the VC indicated that the disease spread very fast. Incidence increased from 11% in 1989 to 53% in 1998. Toxoptera aurantii and Aphis spiraecola (inefficient aphid vectors of CTV) predominated before 1985–87. Since then the relatively efficient vector Aphis gossypii has become dominant and induced an epidemic that has been modelled. The large number of A.gossypii that…
PT Symmetry and Weyl Asymptotics
2012
For a class of PT-symmetric operators with small random perturbations, the eigenvalues obey Weyl asymptotics with probability close to 1. Consequently, when the principal symbol is nonreal, there are many nonreal eigenvalues.
Complex powers and non-compact manifolds
2002
We study the complex powers $A^{z}$ of an elliptic, strictly positive pseudodifferential operator $A$ using an axiomatic method that combines the approaches of Guillemin and Seeley. In particular, we introduce a class of algebras, ``extended Weyl algebras,'' whose definition was inspired by Guillemin's paper on the subject. An extended Weyl algebra can be thought of as an algebra of ``abstract pseudodifferential operators.'' Many algebras of pseudodifferential operators are extended Weyl algebras. Several results typical for algebras of pseudodifferential operators (asymptotic completeness, construction of Sobolev spaces, boundedness between apropriate Sobolev spaces, >...) generalize to…