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We have built a room temperature amplifier based on Si JFETs (junction field effect transistors) intended for ac-coupled SQUID (superconducting quantum interference device) readouts, such as in frequency-domain multiplexed transition-edge sensor systems. The amplifier operates at 5 MHz centre frequency where it has the measured noise temperature of 27 K for a 60 ? load, which includes the noise from the active termination and the room temperature transformer. When it was driven from a SQUID with an on-chip matching transformer, flux noise of 0.45 ??0Hz?1/2was obtained. Additionally, we consider the potential of the recently introduced SiGe bipolar transistors for the same application. The dynamic range considerations for SQUID multiplexers, which require the use of an amplifier with a low noise temperature, are briefly discussed.

We have developed a set of dc SQUIDs intended for frequency-domain multiplexed readout of transition edge sensor (TES) arrays. The first design is based on the Ketchen-style washer, and has exhibited a 1.2 × 10⁻⁷ Φ₀ Hz^1/2 flux noise both at 4.2 and 0.43 K. The second design is based on the multiloop structure and utilizes the spoke-terminating resistors which double as junction shunts in order to minimize the excess noise due to the resonance damping. The multiloop device has exhibited a 3.5 × 10⁻⁷ Φ₀ Hz^1/2 flux noise level at 4.2 K. The mutual inductances are chosen such that a typical ac-biased TES-based x-ray calorimeter would need only a moderate amount of negative feedback in order to handle the dynamic range of the signal.

BackgroundA rat line developed by selective breeding for high alcohol sensitivity has blunted corticosterone responses to alcohol and stress. In the present study, we determined possible differences in adrenal activation after alcohol and motor performance testing between the alcohol‐sensitive alcohol‐nontolerant and alcohol‐insensitive alcohol‐tolerant rats.

ABSTRACTClostridium botulinumtype B was detected by multiplex PCR in the intestinal contents of a suddenly deceased 11-week-old infant and in vacuum cleaner dust from the patient's household. C. botulinumwas also isolated from the deceased infant's intestinal contents and from the household dust. The genetic similarity of the two isolates was demonstrated by pulsed-field gel electrophoresis and randomly amplified polymorphic DNA analysis, thereby confirming that dust may act as a vehicle for infant botulism that results in sudden death.