Fully differential photo-electron spectra of hydrogen and helium atoms

The ability to probe and manipulate electron dynamics and correlations on their characteristic time scales would open up many technological and scientific possibilities. While modern laser technology already allows to do that in principle, a lot of theoretical ground work is still missing. This thesis focuses on the elementary effect of laser strong field ionization of the two simplest systems: The Hydrogen and Helium atoms. To that end, the time-dependent Schroedinger equation is solved numerically, and photo-electron spectra are extracted using the highly efficient tSurff technique. We implemented both the one and two particle versions of tSurff together with several other numerical techniques in a new parallelizable C++ code. We provide details on the employed methods and algorithms, and study numerical efficiency properties of various approaches. We propose a description of the electric field interaction in a mixture of length and velocity gauge for the correct and most efficient implementation of a coupled channels approach, which can be used to compute accurate single ionization photo-electron spectra from true multi-electron systems, even molecules. We provide extensive numerical data for a detailed study of the Hydrogen atom in an Attoclock experimental setup, where it is found that the involved strong field tunnel ionization processes can be considered instantaneous. In particular, there appear no tunneling delays, which can be used as a calibration for experiments with more complicated targets. Similarly, it is investigated whether discrepancies between theory and experimental data for the longitudinal photo-electron momentum spread, resulting from photo-ionization of Helium in elliptically polarized laser pulses, can be explained by non-adiabatic effects, and a related consistency problem in current laser intensity calibration methods is pointed out. We further show that Fano resonance line shapes of doubly excited states in the Helium atom, prominently appearing in single ionization spectra generated by short wavelength laser pulses, can be controlled by an external long wavelength streaking field. The resulting line shapes are still characterized by the general Fano situation, but with a complex - rather than real - Fano parameter. We provide a theoretical description of this two color process and prove numerically that the entire doubly excited state series exhibits synchronized line shape modifications as the specifics of the involved states are unimportant. Finally, we compute fully differential double ionization spectra and suggest a measure of correlation that is directly applicable to experimental data. We confirm literature results at short wavelengths, and achieve to compute five-fold differential double ionization photo-electron spectra at infrared wavelengths from the Helium atom, thereby reproducing a characteristic several orders of magnitude enhancement of double emission due to correlation effects

Photoionization of few electron systems with a hybrid Coupled Channels approach

We present the hybrid anti-symmetrized coupled channels method for the calculation of fully differential photo-electron spectra of multi-electron atoms and small molecules interacting with strong laser fields. The method unites quantum chemical few-body electronic structure with strong-field dynamics by solving the time dependent Schr\"odinger equation in a fully anti-symmetrized basis composed of multi-electron states from quantum chemistry and a one-electron numerical basis. Photoelectron spectra are obtained via the time dependent surface flux (tSURFF) method. Performance and accuracy of the approach are demonstrated for spectra from the helium and berryllium atoms and the hydrogen molecule in linearly polarized laser fields at wavelength from 21 nm to 400 nm. At long wavelengths, helium and the hydrogen molecule at equilibrium inter-nuclear distance can be approximated as single channel systems whereas beryllium needs a multi-channel description

Global attractors and extinction dynamics of cyclically competing species

Transitions to absorbing states are of fundamental importance in nonequilibrium physics as well as ecology. In ecology, absorbing states correspond to the extinction of species. We here study the spatial population dynamics of three cyclically interacting species. The interaction scheme comprises both direct competition between species as in the cyclic Lotka-Volterra model, and separated selection and reproduction processes as in the May-Leonard model. We show that the dynamic processes leading to the transient maintenance of biodiversity are closely linked to attractors of the nonlinear dynamics for the overall species' concentrations. The characteristics of these global attractors change qualitatively at certain threshold values of the mobility and depend on the relative strength of the different types of competition between species. They give information about the scaling of extinction times with the system size and thereby the stability of biodiversity. We define an effective free energy as the negative logarithm of the probability to find the system in a specific global state before reaching one of the absorbing states. The global attractors then correspond to minima of this effective energy landscape and determine the most probable values for the species' global concentrations. As in equilibrium thermodynamics, qualitative changes in the effective free energy landscape indicate and characterize the underlying nonequilibrium phase transitions. We provide the complete phase diagrams for the population dynamics and give a comprehensive analysis of the spatio-temporal dynamics and routes to extinction in the respective phases

Fully differential photo-electron spectra of hydrogen and helium atoms

The ability to probe and manipulate electron dynamics and correlations on their characteristic time scales would open up many technological and scientific possibilities. While modern laser technology already allows to do that in principle, a lot of theoretical ground work is still missing. This thesis focuses on the elementary effect of laser strong field ionization of the two simplest systems: The Hydrogen and Helium atoms. To that end, the time-dependent Schroedinger equation is solved numerically, and photo-electron spectra are extracted using the highly efficient tSurff technique. We implemented both the one and two particle versions of tSurff together with several other numerical techniques in a new parallelizable C++ code. We provide details on the employed methods and algorithms, and study numerical efficiency properties of various approaches. We propose a description of the electric field interaction in a mixture of length and velocity gauge for the correct and most efficient implementation of a coupled channels approach, which can be used to compute accurate single ionization photo-electron spectra from true multi-electron systems, even molecules. We provide extensive numerical data for a detailed study of the Hydrogen atom in an Attoclock experimental setup, where it is found that the involved strong field tunnel ionization processes can be considered instantaneous. In particular, there appear no tunneling delays, which can be used as a calibration for experiments with more complicated targets. Similarly, it is investigated whether discrepancies between theory and experimental data for the longitudinal photo-electron momentum spread, resulting from photo-ionization of Helium in elliptically polarized laser pulses, can be explained by non-adiabatic effects, and a related consistency problem in current laser intensity calibration methods is pointed out. We further show that Fano resonance line shapes of doubly excited states in the Helium atom, prominently appearing in single ionization spectra generated by short wavelength laser pulses, can be controlled by an external long wavelength streaking field. The resulting line shapes are still characterized by the general Fano situation, but with a complex - rather than real - Fano parameter. We provide a theoretical description of this two color process and prove numerically that the entire doubly excited state series exhibits synchronized line shape modifications as the specifics of the involved states are unimportant. Finally, we compute fully differential double ionization spectra and suggest a measure of correlation that is directly applicable to experimental data. We confirm literature results at short wavelengths, and achieve to compute five-fold differential double ionization photo-electron spectra at infrared wavelengths from the Helium atom, thereby reproducing a characteristic several orders of magnitude enhancement of double emission due to correlation effects

Characterization and comparison of strains of Pasteurella multocida associated with cases of progressive atrophic rhinitis and porcine pneumonia in Argentina

Pasteurella multocida (Pm) is the causative agent of progressive atrophic rhinitis (PAR) and pneumonicpasteurellosis (PN) in pigs. Pm is a member of the porcine respiratory complex responsible for important economic loss inthe pig industry. This study aimed to characterize the Pm strains recovered from clinical cases of PN and PAR and to elucidate theantibiotic susceptibility profiles of the strains.Materials and Methods: Sixty strains were characterized molecularly by polymerase chain reaction to determine speciesspecific gene, capsular type (A or D), and toxin A production. The agar diffusion method was employed to evaluate antibioticresistance profiles. We found that 65% of strains belonged to capsular type A or D, and 15% of those were positive to toxA gene.The antibiotic susceptibility profiles found were sensitive in decreasing order to: Enrofloxacin, ceftiofur (CTF), ampicillin,tilmicosin (TIL), florfenicol (FFN), spectinomycin (SPC), gentamicin, oxytetracycline (OTC), and trimethoprimsulfamethoxazole (TMS). Strains were resistant in decreasing order to: Lincomycin (LIN), tylosin (TYL), erythromycin(ERY), TMS, SPC, OTC, FFN, TIL, and CTF. The toxA gene was detected in many Pm isolates from pneumonic lungs. Capsule type A or D was the mostfrequently found among the collected isolates. LIN, TYL, and ERY are the drugs which showed higher percentages of resistant isolates.Fil: Bessone, Fernando Anibal. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Córdoba. Estación Experimental Agropecuaria Marcos Juárez; ArgentinaFil: Soriano Pérez, María Laura. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Córdoba. Estación Experimental Agropecuaria Marcos Juárez; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zielinski, Gustavo Carlos. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Córdoba. Estación Experimental Agropecuaria Marcos Juárez; ArgentinaFil: Dibárbora, Marina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Córdoba. Estación Experimental Agropecuaria Marcos Juárez; ArgentinaFil: Conde, María Belén. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Córdoba. Estación Experimental Agropecuaria Marcos Juárez; ArgentinaFil: Cappuccio, Javier Alejandro. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alustiza, Fabrisio Eduardo. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Departamento de Química; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Évaluation de la pneumonie porcine à l’abattage en utilisant la réaction d’amplification en chaine par la polymérase et l’histopathologie en Argentine

Se realizó la reacción en cadena de polimerasa e histopatología en 81 pulmones recolectados en el matadero de 13 granjas porcinas libres del síndrome reproductivo y respiratorio porcino, y de la infección por el virus de la pseudorabia. La Pasteurella multocida y el Mycoplasma hyopneumoniae fueron los patógenos más comúnmente detectados. La bronconeumonía supurativa y catarral estuvieron presentes en 59 (72.8%) casos.Histopathology and polymerase chain reaction were conducted on 81 lungs collected at slaughter from 13 swine farms free of porcine reproductive and respiratory syndrome virus and pseudorabies virus infection. Pasteurella multocida and Mycoplasma hyopneumoniae were the most common pathogens detected. Suppurative and catarrhal bronchopneumonia was present in 59 (72.8%) cases.L’histopathologie et la réaction d’amplification en chaine par la polymérase ont été réalisées sur 81 poumons récoltés à l’abattoir provenant de 13 fermes porcines exemptes du virus du syndrome reproducteur et respiratoire porcin et d’infection par le virus de la pseudorage. Pasteurella multocida et Mycoplasma hyopneumoniae étaient les agents pathogènes les plus communément détectés. Une bronchopneumonie suppurative et catarrhale était présente dans 59 (72.8%) cas.Fil: Cappuccio, Javier Alejandro. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Córdoba. Estación Experimental Agropecuaria Marcos Juárez; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Dibárbora, Marina. Instituto Nacional de Tecnología Agropecuaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bessone, Fernando Anibal. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Córdoba. Estación Experimental Agropecuaria Marcos Juárez; ArgentinaFil: Olivera, Valeria. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Virología; ArgentinaFil: Lozada, María Inés. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Departamento de Patología. Cátedra de Patología Especial Veterinaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alustiza, Fabrisio Eduardo. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Córdoba. Estación Experimental Agropecuaria Marcos Juárez; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Quiroga, María Alejandra. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Departamento de Patología. Cátedra de Patología Especial Veterinaria; ArgentinaFil: Pérez, Estefanía Marisol. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Departamento de Patología. Cátedra de Patología Especial Veterinaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zielinski, Gustavo Carlos. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Córdoba. Estación Experimental Agropecuaria Marcos Juárez; ArgentinaFil: Perfumo, Carlos Juan. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Departamento de Patología. Cátedra de Patología Especial Veterinaria; ArgentinaFil: Pereda, Ariel Julián. Instituto Nacional de Tecnología Agropecuaria. Centro de Investigación en Ciencias Veterinarias y Agronómicas. Instituto de Patobiología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Pérez, Daniel R.. University of Georgia; Estados Unido