Search results for "Linear"
showing 10 items of 7165 documents
Role of topological phase-defects in the parametric generation process
2008
Abstract We show that topological phase-defects are spontaneously generated from noise fluctuations in the degenerate configuration of the parametric interaction. These localized coherent structures are shown to affect the coherence properties of the parametrically generated field. It is shown that the emergence of coherence in the fundamental field relies on a previously unrecognized process of mutual annihilation of pairs of neighboring phase-defects. More precisely, the density of phase-defects N , and the time correlation τ c of the generated field, are shown to exhibit a power-law behavior with the propagation length, i.e., τ c ∝ z 1 / 4 , N ∝ z - 1 / 4 .
Genetic diversity and trait genomic prediction in a pea diversity panel
2014
Background Pea (Pisum sativum L.), a major pulse crop grown for its protein-rich seeds, is an important component of agroecological cropping systems in diverse regions of the world. New breeding challenges imposed by global climate change and new regulations urge pea breeders to undertake more efficient methods of selection and better take advantage of the large genetic diversity present in the Pisum sativum genepool. Diversity studies conducted so far in pea used Simple Sequence Repeat (SSR) and Retrotransposon Based Insertion Polymorphism (RBIP) markers. Recently, SNP marker panels have been developed that will be useful for genetic diversity assessment and marker-assisted selection. Resu…
Sex-dependent genetic markers of CYP3A4 expression and activity in human liver microsomes
2007
Objective: To find genetic markers of the individual cytochrome P450 (CYP)3A expression. Methods: A large collection of liver samples phenotyped for CYP3A expression and activity was genotyped for CYP3A variants. Data were analyzed for associations between CYP3A phenotypes and genotypes, and for evidence of recent selection. Results: We report associations between the hepatic CYP3A4 protein expression level, as well as its enzymatic activity, measured as verapamil N-dealkylation, and genetic polymorphisms from two regions within the CYP3A gene cluster. One region is defined by several variants, mostly located within CYP3A7, the other by a single nucleotide polymorphism in intron 7 of CYP3A…
Plasma clearance of human low-density lipoprotein in human apolipoprotein B transgenic mice is related to particle diameter.
2004
To test for intrinsic differences in metabolic properties of low-density lipoprotein (LDL) as a function of particle size, we examined the kinetic behavior of 6 human LDL fractions ranging in size from 251 to 265 A injected intravenously into human apolipoprotein (apo) B transgenic mice. A multicompartmental model was formulated and fitted to the data by standard nonlinear regression using the Simulation, Analysis and Modeling (SAAM II) program. Smaller sized LDL particles (251 to 257 A) demonstrated a significantly slower fractional catabolic rate (FCR) (0.050 +/- 0.045 h(-1)) compared with particles of larger size (262 to 265 A) (0.134 +/- -0.015 h(-1), P.03), and there was a significant …
Diseased Social Predators
2017
Social predators benefit from cooperation in the form of increased hunting success, but may be at higher risk of disease infection due to living in groups. Here, we use mathematical modeling to investigate the impact of disease transmission on the population dynamics benefits provided by group hunting. We consider a predator-prey model with foraging facilitation that can induce strong Allee effects in the predators. We extend this model by an infectious disease spreading horizontally and vertically in the predator population. The model is a system of three nonlinear differential equations. We analyze the equilibrium points and their stability as well as one- and two-parameter bifurcations. …
Suppression law of quantum states in a 3D photonic fast Fourier transform chip
2015
The identification of phenomena able to pinpoint quantum interference is attracting large interest. Indeed, a generalization of the Hong–Ou–Mandel effect valid for any number of photons and optical modes would represent an important leap ahead both from a fundamental perspective and for practical applications, such as certification of photonic quantum devices, whose computational speedup is expected to depend critically on multi-particle interference. Quantum distinctive features have been predicted for many particles injected into multimode interferometers implementing the Fourier transform over the optical modes. Here we develop a scalable approach for the implementation of the fast Fouri…
Frequency-dependent selection in human immunodeficiency virus type 1.
2001
Genetic variation is the main evolutionary strategy adopted by RNA viruses and retroviruses. Evolution operates through competition between different individuals in the same environment, resulting in the imposition of the fittest variant. The process of competition could be affected by various factors, including the frequency of the different competing individuals. In order to investigate this aspect, individual virus populations derived from a human immunodeficiency virus type 1 isolate were studied at different competing proportions. The dynamics of variant imposition in each competition experiment permitted the detection of frequency-dependent selection (FDS); i.e. the imposition of vari…
Impact of Parkinson's disease risk loci on age at onset
2015
Background The aim of this study was to assess whether recently identified Parkinson's disease (PD) risk genes also influence age at onset in PD. Methods We genotyped 23 single-nucleotide polymorphisms in 1,526 Danish PD patients and performed linear regression analyses with age at onset. The combined impact of PD risk loci on age at onset was assessed by linear regression analyses using a weighted genetic risk score. Results The strongest effects were observed with rs12726330 in GBA (beta = –3.63, P = 2.0 × 10−5) and rs34311866 in TMEM175/GAK (beta = –1.19, P = 4.0 × 10−3), corresponding to a 3.6-y and 1.2-y decrease of age at onset per risk allele, respectively. The weighted genetic risk …
High resistance to X-rays and therapeutic carbon ions in glioblastoma cells bearing dysfunctional ATM associates with intrinsic chromosomal instabili…
2014
To investigate chromosomal instability and radiation response mechanisms in glioblastoma cells.We undertook a comparative analysis of two patient-derived glioblastoma cell lines. Their resistance to low and high linear energy transfer (LET) radiation was assessed using clonogenic survival assay and their intrinsic chromosome instability status using fluorescence in situ hybridization. DNA damage was analyzed by pulsed-field gel electrophoresis and by γ-H2AX foci quantification. Expression of DNA damage response proteins was assessed by immunoblot.Increased radioresistance to X-rays as well as carbon ions was observed in glioblastoma cells exhibiting high levels of naturally occurring chromo…
Heterogeneity of HVR-1 quasispecies is predictive of early but not sustained virological response in genotype 1b-infected patients undergoing combine…
2003
ISDR mutation pattern and HVR-1 quasispecies were analyzed in HCV genotype 1b-infected patients treated with either PEG- or STD-IFN plus ribavirin, in order to find virological correlates of therapy outcome. ISDR region analysis, performed at baseline (T0) and at 4 weeks of therapy (T1), indicated that ISDR mutation pattern was not predictive of response to treatment. Moreover, no selection of putative resistant strains in the first month of therapy was observed. Viral load was not correlated with any parameter of HVR-1 heterogeneity. Among the HVR-1 heterogeneity parameters considered, complexity was inversely correlated to viral load decline at T1. In univariate analysis, complexity, prop…