Advanced mesospheric temperature mapper for high-latitude airglow studies.

Over the past 60 years, ground-based remote sensing measurements of the Earth's mesospheric temperature have been performed using the nighttime hydroxyl (OH) emission, which originates at an altitude of ∼87 km. Several types of instruments have been employed to date: spectrometers, Fabry-Perot or Michelson interferometers, scanning-radiometers, and more recently temperature mappers. Most of them measure the mesospheric temperature in a few sample directions and/or with a limited temporal resolution, restricting their research capabilities to the investigation of larger-scale perturbations such as inertial waves, tides, or planetary waves. The Advanced Mesospheric Temperature Mapper (AMTM) is a novel infrared digital imaging system that measures selected emission lines in the mesospheric OH (3,1) band (at ∼1.5 µm) to create intensity and temperature maps of the mesosphere around 87 km. The data are obtained with an unprecedented spatial (∼0.5 km) and temporal (typically 30″) resolution over a large 120° field of view, allowing detailed measurements of wave propagation and dissipation at the ∼87 km level, even in the presence of strong aurora or under full moon conditions. This paper describes the AMTM characteristics, compares measured temperatures with values obtained by a collocated Na lidar instrument, and presents several examples of temperature maps and nightly keogram representations to illustrate the excellent capabilities of this new instrument.

Systemic Mycobacterium smegmatis infection in a dog.

A 3-year-old female Basset Hound was examined because of fever and lameness of 2 months' duration. Physical examination revealed a small cranial abdominal mass, which had an ultrasonographic appearance of a large abdominal lymph node. Cytologic examination of an ultrasound-guided fine-needle aspirate of the mass revealed a few macrophages that contained numerous linear unstained structures consistent with mycobacteria. Intracellular acid-fast bacilli were identified in an aspirate that was stained with modified Ziehl-Neelsen. Exploratory laparotomy revealed wide-spread abdominal lymphadenopathy. Histologic examination of hepatic and lymph node biopsy specimens revealed chronic granulomatous hepatitis and lymphadenitis. Acid-fast organisms isolated after bacteriologic culturing of a mesenteric lymph node specimen were identified as Mycobacterium smegmatis. Because the prognosis was poor, the dog was euthanatized.

Multiplexed dispersive spectrometers using reduced background infrared detectors.

The application of multiplex spectrometry to cryogenically cooled LWIR extrinsic photodetectors is limited by system noise. This noise limitation results in a detector NEP that is directly proportional to bandwidth. Therefore, multiplex schemes that require increased bandwidth are not productive of real advantage. However, doubly encoded systems that are based on 2n - 1 or n + N - 1 measurements have the potential to provide a real throughput gain proportional to the number of elements used on the throughput matrix.