Measurement technology of operation region of EVA spacesuit
Operation ability of astronaut in spacesuit is a key parameter in Extra-vehicular activities. The operation region of people in the spacesuit was tested by 3-jointed mechanical measuring arm, which combined force-torque sensors in the handle, and magnetic brakes installed in every joint. Mathematical model of the measuring arm was established to transform the signals of sensors to the data required. The errors were analyzed and the system was calibrated and compensated. All tests were aided by computer, and data obtained were processed by software developed based on VC++, OpenGL and Matlab. An exact 3- D operation region of left hand, right hand and both hands was obtained by a method of reverse engineering. The measurement supplied solid support in space engineering design.
Errors Analysis and Calibration on Measuring Mechanical Arm for EVA Spacesuit Ergonomics Research
A combined coordinate measuring mechanical arm (CCMMA) was developed to test the operational ability of astronaut in the EVA spacesuit. The equipment measures the space region coordinates of the astronaut’s hand-reach while forces act on a handle. The homogeneous transformation equations of CCMMA are established based on Modified Denavit-Hartenberg (MDH). Measurement error was analyzed and distance error model of CCMMA was set up to improve measurement precision. The improved genetic algorithm is applied to the identification of CCMMA structure parameters. The calibration experiment of CCMMA was carried out using such model and algorithm. The result showed that with identification, the repeatability and length measurement precision were improved by 5.38 and 3.11 times respectively.
Coexistence of Virulence and Antibiotic Resistance Genes in Pasteurella multocida Isolated from Diseased Rabbits
Pasteurella multocida (P. multocida)is considered a predominant pathogenic bacterial agent causing respiratory manifestations (snuffles) in rabbits with considerable economic losses and unfavorable prognosis in Egypt. A few recent P. multocida strains exhibit resistance to the most commonly used antibiotics in the veterinary field. Therefore, the present study was carried out to investigate the prevalence of both virulence and antibiotic resistance genes among P. multocida isolated from diseased rabbits in Sharkia Governorate, Egypt. Only 10 out of 100 tested rabbits` nasal swabs were finally confirmed positive for P. multocida of serogroup A by polymerase chain reaction (PCR). Antibiotic susceptibility testing of the recovered isolates revealed that they were all multidrug resistant (MDR) with a predominance of resistance to amoxicillin, ampicillin, amoxicillin/clavulanic acid, neomycin and tetracycline (100% each), followed by kanamycin and streptomycin (90% each). All the recovered isolates were further subjected to PCR screening of some common virulence and antibiotic resistance genes of interest . With the exception of toxA gene, the other virulence associated genes (ptfA, Omp87 and nanB) were found among all the examined isolates. Totally, all MDR P. multocida isolates contained at least one antibiotic resistance gene with aphA1 being the most prevalent (100%), followed by ermX gene (40%). Antibiotic resistance genotyping demonstrated the presence of multiple antibiotic resistance genes among majority of the isolates (40%) with only one isolate harboring 4 genes encoding identical resistance phenotypes. Evidentially, all MDR P. multocida isolates possessed at least 3 virulence genes accompanied by the attendance of antibiotic resistance genes. These findings evidenced that rabbits are potential sources of pathogenic P. multocida strains harboring virulence and antibiotic resistance genes. Therefore, it is evident that there is an urgent need for the judicious use of antibiotics in rabbits` treatment systems to successfully mitigate the propagation of drug resistance across P. multocida species.