Pasteurella multocida type A as the primary agent of pneumonia and septicaemia in pigs

Abstract: In order to understand better the pathological aspects and spread of Pasteurella multocida type A as the primary cause of pneumonia in pigs, was made an experiment with intranasal inoculation of different concentrations of inocula [Group (G1): 108 Colony Forming Units (CFU)/ml; G2: 107 CFU/ml; G3: 106 CFU/ml and G4: 105 CFU/ml], using two pigs per group. The pigs were obtained from a high health status herd. Pigs were monitored clinically for 4 days and subsequently necropsied. All pigs had clinical signs and lesions associated with respiratory disease. Dyspnoea and hyperthermia were the main clinical signs observed. Suppurative cranioventral bronchopneumonia, in some cases associated with necrosuppurative pleuropneumonia, fibrinous pericarditis and pleuritic, were the most frequent types of lesion found. The disease evolved with septicaemia, characterized by septic infarctions in the liver and spleen, with the detection of P. multocida type A. In this study, P. multocida type A strain #11246 was the primary agent of fibrinous pleuritis and suppurative cranioventral bronchopneumonia, pericarditis and septicaemia in the pigs. All concentrations of inoculum used (105-108 CFU/ml) were able to produce clinical and pathological changes of pneumonia, pleuritis, pericarditis and septicemia in challenged animals

Interactions between asteroid fragments during atmospheric entry

The current work explores the interactions between asteroid fragments and the associated flow topology to motivate a physically consistent representation of the fragmentation process following a fragmentation event during atmospheric entry. Multibody aerodynamic simulations run with computational fluid dynamics (CFD) solvers were used to generate a lookup table of forces detailing the interactions of two spheres. Trajectory simulations parsing the resulting database to determine the relative motions of any two spherical fragments were then validated with hypersonic wind tunnel experiments. A following series of fragment interaction simulations yielded categorization of the fragments' final relative states and an estimate of the total time of interaction. The fragment interaction model was nondimensionalized to permit study over a wide range of possible asteroid impacts. The interaction parameters are presented with explicit semi-analytic equations, defining the asteroid fragment-flow interaction model and thereby eliminating the need to perform a separate fragment interaction simulation for each fragmentation event in an atmospheric entry model. Finally, a set of illustrative examples demonstrates the efficacy of the model in a variety of fragmentation situations