Self-similar dynamics of bacterial chemotaxis

Colonies of bacteria grown on thin agar plate exhibit fractal patterns as a result of adaptation to their environments. The bacterial colony pattern formation is regulated crucially by chemotaxis, the movement of cells along a chemical concentration gradient. Here, the dynamics of pattern formation in bacterial colony is investigated theoretically through a continuum model that considers chemotaxis. In the case of the gradient sensed by the bacterium is nearly uniform, the bacterial colony patterns are self-similar, which they look the same at every scale. The scaling law of the bacterial colony growth has been revealed explicitly. Chemotaxis biases the movement of bacterial population in colony trend toward the chemical attractant. Moreover, the bacterial colonies evolve long time as the traveling wave with sharp front.Comment: 4 pages, 3 figures, accepted by Phys. Rev. E (Brief Report

Self-Similar Solutions to a Density-Dependent Reaction-Diffusion Model

In this paper, we investigated a density-dependent reaction-diffusion equation, $u_t = (u^{m})_{xx} + u - u^{m}$. This equation is known as the extension of the Fisher or Kolmogoroff-Petrovsky-Piscounoff equation which is widely used in the population dynamics, combustion theory and plasma physics. By employing the suitable transformation, this equation was mapped to the anomalous diffusion equation where the nonlinear reaction term was eliminated. Due to its simpler form, some exact self-similar solutions with the compact support have been obtained. The solutions, evolving from an initial state, converge to the usual traveling wave at a certain transition time. Hence, it is quite clear the connection between the self-similar solution and the traveling wave solution from these results. Moreover, the solutions were found in the manner that either propagates to the right or propagates to the left. Furthermore, the two solutions form a symmetric solution, expanding in both directions. The application on the spatiotemporal pattern formation in biological population has been mainly focused.Comment: 5 pages, 2 figures, accepted by Phys. Rev.

Feasibility studies for the measurement of time-like proton electromagnetic form factors from p¯ p→ μ+μ- at P ¯ ANDA at FAIR

This paper reports on Monte Carlo simulation results for future measurements of the moduli of time-like proton electromagnetic form factors, | GE| and | GM| , using the p¯ p→ μ+μ- reaction at P ¯ ANDA (FAIR). The electromagnetic form factors are fundamental quantities parameterizing the electric and magnetic structure of hadrons. This work estimates the statistical and total accuracy with which the form factors can be measured at P ¯ ANDA , using an analysis of simulated data within the PandaRoot software framework. The most crucial background channel is p¯ p→ π+π-, due to the very similar behavior of muons and pions in the detector. The suppression factors are evaluated for this and all other relevant background channels at different values of antiproton beam momentum. The signal/background separation is based on a multivariate analysis, using the Boosted Decision Trees method. An expected background subtraction is included in this study, based on realistic angular distributions of the background contribution. Systematic uncertainties are considered and the relative total uncertainties of the form factor measurements are presented

PANDA Phase One - PANDA collaboration

The Facility for Antiproton and Ion Research (FAIR) in Darmstadt, Germany, provides unique possibilities for a new generation of hadron-, nuclear- and atomic physics experiments. The future antiProton ANnihilations at DArmstadt (PANDA or P¯ANDA) experiment at FAIR will offer a broad physics programme, covering different aspects of the strong interaction. Understanding the latter in the non-perturbative regime remains one of the greatest challenges in contemporary physics. The antiproton–nucleon interaction studied with PANDA provides crucial tests in this area. Furthermore, the high-intensity, low-energy domain of PANDA allows for searches for physics beyond the Standard Model, e.g. through high precision symmetry tests. This paper takes into account a staged approach for the detector setup and for the delivered luminosity from the accelerator. The available detector setup at the time of the delivery of the first antiproton beams in the HESR storage ring is referred to as the Phase One setup. The physics programme that is achievable during Phase One is outlined in this paper

Morphological characterization of canine retrobulbar lymphoma

This report characterized seven cases of canine retrobulbar lymphoma that have been diagnosed during 2008 to 2014 by immunophenotyping of CD3 and Pax5. Classification of lymphoma were performed according to the revised WHO guidelines. Four retrobulbar lymphomas were of T-cell origin, while the others were of B-cell. Out of 7 cases, four subtypes were diagnosed in this study; T-cell-rich large B-cell lymphoma (3/7), T-cell lymphoblastic lymphoma (2/7), peripheral T-cell lymphoma (1/7), and cutaneous nonepitheliotropic lymphoma (1/7). T-cell-rich large B-cell lymphoma was found to be the most frequent subtype found

Novel psbA1 Gene from a Naturally Occurring Atrazine-Resistant Cyanobacterial Isolate

A naturally occurring atrazine-resistant cyanobacterial isolate, strain SG2, was isolated from an atrazine-containing wastewater treatment system at the Syngenta atrazine production facility in St. Gabriel, La. Strain SG2 was resistant to 1,000 μg of atrazine per ml but showed relatively low resistance to diuron [3-(3,4-dichlorophenyl)-1,1-dimethyl urea]. Analyses of 16S ribosomal DNA indicated that strain SG2 falls into the Synechocystis/Pleurocapsa/Microcystis group. Photosynthetically driven oxygen evolution in strain SG2 was only slightly inhibited (about 10%) by 2,000 μg of atrazine per ml, whereas in the control strain Synechocystis 6803, oxygen evolution was inhibited 90% by 1,000 μg of atrazine per ml. No atrazine accretion, mineralization, or metabolites were detected when strain SG2 was grown with [(14)C]atrazine. Strain SG2 contained three copies of the psbA gene, which encodes the D(1) protein of the photosystem II reaction center. Nucleotide sequence analyses indicated that the psbA2 and psbA3 genes encoded predicted proteins with the same amino acid sequence. However, the psbA1 gene product contained five extra amino acids, which were not found in PsbA proteins from five other cyanobacteria. Moreover, the PsbA1 protein from strain SG2 had an additional 13 amino acid changes compared to the PsbA2/PsbA3 proteins and contained 10 amino acid alterations compared to conserved residues found in other cyanobacteria. Reverse transcriptase PCR analysis indicated that the psbA1 gene and the psbA2/psbA3 gene(s) were expressed in photosynthetically grown cells in the presence of atrazine. These results suggest that strong selection pressure conferred by the continual input of atrazine has contributed to the evolution of a herbicide-resistant, yet photosynthetically efficient, psbA gene in a cyanobacterium