We reexamined the finding of Neumann et al. (10) that intact Cryptosporidium parvum oocysts obtained after in vitro excystation were infectious for neonatal CD-1 mice. We used both established excystation protocols and our own protocol that maximized excystation (2). Although intact oocysts isolated after any of three protocols were infectious for neonatal CD-1 mice, the infectivity of intact oocysts isolated with our optimized excystation protocol was significantly lower than the infectivity of intact oocysts isolated after established protocols or from fresh oocysts. Excystation should not be considered a valid measure of C. parvum viability, given that it is biologically implausible for oocysts to be nonviable and yet infectious.The use of excystation as an indicator of Cryptosporidium parvum oocyst viability has come under criticism, given the observation that intact oocysts isolated after in vitro excystation were infectious for CD-1 neonatal mice (10). The presumption is that if an oocyst cannot excyst, it will be incapable of the physical and biochemical steps involved in initiating asexual multiplication (6, 7). Using established in vitro procedures, previous studies have found a wide discrepancy in the proportion of oocysts that excyst, ranging from 50 to 95% depending on which technique was used to stimulate excystation, such as pretreatment of oocysts with acid (2, 4, 5, 10, 12). Such a wide discrepancy in excystation rates for the same batch of oocysts indicates that some excystation protocols fail to fully stimulate oocysts to excyst, resulting in excessive amounts of intact oocysts following the procedure. This result not only leads to underestimating the proportion of oocysts that are presumably viable but also biases experiments that use intact oocysts isolated after in vitro excystation.Our concern with the conclusion that intact oocysts isolated after in vitro excystation are infectious for CD-1 neonatal mice (10) is that the process of excystation appeared not to be optimized, resulting in substantial numbers of excystable (i.e., viable) oocysts failing to excyst, thereby explaining the infectious potential of such oocysts for neonatal mice. Our goal for this project was to reexamine the finding that intact C. parvum oocysts obtained after in vitro excystation were infectious for neonatal CD-1 mice, using a protocol that maximized the proportion of oocysts that excysted (2), resulting in a more valid population of intact, presumably nonviable oocysts for in vivo experimentation.C. parvum oocysts. Feces were collected from naturally infected calves at 9 to 21 days of age from three local commercial dairies in Tulare, Calif., which served as the source of wild-type C. parvum oocysts for these experiments. These oocysts were previously classified as bovine genotype A, using the genotyping scheme described by Xiao et al. (13). After an acid faststaining procedure was used to detect oocysts (9), samples having more than 25 oocysts per microscopic field (400ϫ) of fecal smears were washed through a s...
System-on-chip millimeter wave integrated circuit technology is used on the two-dimensional millimeter-wave imaging reflectometer (MIR) upgrade for density fluctuation imaging on the DIII-D tokamak fusion plasma. Customized CMOS chips have been successfully developed for the transmitter module and receiver module array, covering the 55–75 GHz working band. The transmitter module has the capability of simultaneously launching eight tunable probe frequencies (>0 dBm output power each). The receiver enclosure contains 12 receiver modules in two vertical lines. The quasi-optical local oscillator coupling of previous MIR systems has been replaced with an internal active frequency multiplier chain for improved local oscillator power delivery and flexible installation in a narrow space together with improved shielding against electromagnetic interference. The 55–75 GHz low noise amplifier, used between the receiver antenna and the first-stage mixer, significantly improves module sensitivity and suppresses electronics noise. The receiver module has a 20 dB gain improvement compared with the mini-lens approach and better than −75 dBm sensitivity, and its electronics noise temperature has been reduced from 55 000 K down to 11 200 K. The V-band MIR system is developed for co-located multi-field investigation of MHD-scale fluctuations in the pedestal region with W-band electron cyclotron emission imaging on DIII-D tokamak.
Forward modeling is used to interpret inversion patterns of the pedestal–Scrape of Layer (SOL) Electron Cyclotron Emission (ECE) in DIII-D H-mode experiments. The modeling not only significantly improves the ECE data interpretation quality but also leads to the potential measurements of (1) the magnetic field strength |B| at the separatrix, (2) the pedestal |B| evolution during an inter-Edge Localized Mode (ELM) period, and (3) the pedestal Magnetohydrodynamics (MHD) radial structure. The ECE shine-through effect leads to three types of pedestal–SOL radiation inversions that are discussed in this paper. The first type of inversion is the non-monotonic T e, rad profile with respect to the major radius. Using the ECE frequency at the minimum T e, rad, the inversion can be applied to measure the magnetic field |B| at the separatrix and calibrate the mapping of the ECE channels with respect to the separatrix. The second type of inversion refers to the opposite phase between the radiation fluctuations δT e, rad at the pedestal and SOL. This δT e, rad phase inversion is sensitive to density and temperature fluctuations at the pedestal foot and, thus, can be used to qualitatively measure the MHD radial structure. The third type of inversion appears when the pedestal and SOL T e, rad evolve in an opposite trend, which can be used to infer the pedestal |B| field change during an inter-ELM period. The bandwidth effect on measuring δT e, rad due to pedestal MHD is also investigated in the radiation modeling.
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