Pseudomicrodochium fusarioides sp. nov., isolated from human bronchial fluid

A fungus from bronchial lavage fluid from a patient with pulmonary infiltration was isolated in pure culture and identified as a species of Pseudomicrodochium. It is compared and contrasted with other species of the genus, in particular P. suttonii, and formally described as P. fusarioides.

Modelling the transverse-mode response of a two-port SAW resonator

An equation is derived for the transverse-mode frequencies of a two-port surface-acoustic-wave (SAW) resonator with uniform reflection gratings. It is postulated that only odd-order (symmetric) transverse modes should be excited in such a grating, due to its symmetrical placement with respect to the interdigital transducer (IDT). Frequency response modeling involves a summation of one-dimensional transmission-matrix computations for the fundamental mode and participating transverse ones. Excellent agreement is obtained between theory and experiment for a 360-MHz resonator with three close-in transverse modes, attributed to symmetric modes of odd order m=3, 5, 7.

Sampling effect of distributed reflector arrays within a single-phase unidirectional SAW transducer

A noteworthy feature of the group-type single-phase unidirectional transducer is that it can permit wideband low-loss surface-acoustic-wave (SAW) comb filter operation. This is shown to be due to the sampling imposed by the distributed reflector gratings. The capability is illustrated theoretically and experimentally for a 65-MHz comb filter on 128 degrees Y-X lithium niobate, with 5 comb modes of 585-kHz bandwidth each, together with 2.6-dB minimum insertion loss and overall 50% fractional bandwidth.

Design of a phase-locked multimode SAW oscillator

A 60-100 MHz multimode SAW (surface acoustic wave) oscillator with comb spacing Deltaf=10 MHz used a low-loss SPUDT (single-phase unidirectional transducer) comb filter in conjunction with two varactor-based control elements and two feedback loops, for mode selection and stability enhancement over long dwell times. The end aim is to reduce close-in phase noise over that of the unlocked oscillator, corresponding to improved intermediate-term time-domain stability. Frequency deviation was less than 20 Hz over two hours in each of the five comb modes.

Mycology quality assessment: United Kingdom national scheme

A mycology quality assessment scheme introduced in 1986 was assessed: 289 laboratories participated in the scheme, and six distributions, each containing four specimens, were made. Levels of performance varied considerably among participating laboratories: performance was highest with the commoner organisms distributed, but some laboratories, encouragingly, achieved a consistently high level of species identification. A questionnaire distributed to participants showed that a wide range of methods are commonly used, some of which are contrary to good practice. As the scheme continues, selection of organisms considered to be relevant and of use to participants will become difficult.

A theoretical and experimental study of low-loss SAW filters with interdigitated interdigital transducers

A study of low-loss surface-acoustic-wave (SAW) interdigitated interdigital transducer (IIDT) structures is presented. A model based on mixed scattering matrices was used in the analysis. It is shown that the inherent comb frequency response of the IIDT can be smoothed by slanting the transducers in the structure. Alternatively, the combs can be enhanced to produce a compact low-loss feedback element for potential application in multimode oscillators. Experimental verification of the analysis is provided by a 3:2 slanted-finger IIDT filter with a 10% relative bandwidth of 5.9-dB insertion loss, and a comb filter with 13.4-dB insertion loss and comb spacing of about 3 MHz. The measured responses agree quite well with the theory.

Systemic mycosis due to Penicillium marneffei in a patient with antibody to human immunodeficiency virus

Systemic mycosis due to Penicillium marneffei is described in a man infected with human immunodeficiency virus and who had travelled in S.W. China. He responded completely to treatment with amphotericin B and a prolonged course of ketoconazole. Problems of diagnosis are discussed and all previously reported cases reviewed.

Mode selection in a multimode SAW oscillator using FM chirp mixing signal injection

Mode-selection control of a multimode surface-acoustic-wave (SAW) oscillator has been obtained using SAW linear FM chirp signal injection. The prototype 60-100-MHz SAW oscillator design employed a single-phase unidirectional transducer (SPUDT) low-loss comb filter in the feedback loop, with minimum insertion loss of approximately 3.7 dB. Mode selection was achieved using an injection signal derived from the mixed output of two 27.5-52.5-MHz up- and down-chirp SAW filters. Mode switching times of less, similar2 mus were obtained. The device could be useful as a local oscillator on frequency-agile radars, where hopping is required over a moderate number of frequencies.

Polycytella hominis gen. et sp. nov., a cause of human pale grain mycetoma

A hyphomycete isolated from a pale-grain eumycetoma in an indian male patient is described as a species of a new form-genus, Polycytella hominis. The fungus is characterized by elongate multiseptate conidia in which only the apical compartment becomes thick-walled and retains viable cytoplasm. The appearance of P. hominis in the host tissues is described and compared with other pale-grain eumycetomas.

Conidiogenesis of fungi pathogenic for man

Despite an apparent stabilizing of nomenclature and concepts involved in fungal conidiogenesis during the past decade, there is now evidence that a much more complex and demanding approach to the descriptive study of processes involved in conidial formation would allow a more phylogenetically realistic classification of anamorphic fungi. The present review attempts to evaluate data on the human pathogenic molds in light of this new approach and to relate conidiogenesis to the known teleomorph connections of the fungi concerned. It is hoped that by treating the species in groups corresponding to their sexual affinities, it may be possible to infer homologous forms of conidiogenesis by comparative morphology and development.

Disseminated zygomycosis (mucormycosis) caused by Saksenaea vasiformis

A 14-year-old child from Iraq presented with an acute febrile illness accompanied by large necrotic skin lesions and bronchopneumonia from which he subsequently died. The infection was caused by an unusual zygomycete fungus Saksenaea vasiformis. Previous reports of infection with this organism are rare and tissue invasion has usually followed traumatic injury. In the child reported here no predisposing abnormalities were apparent.

A comparative study of dermatophytosis in coal miners and dermatological outpatients

The causative organisms and susceptibility factors were compared in two groups of individuals with tinea pedis, coal miners (234) and dermatological outpatients (244). Trichophyton rubrum was the commonest dermatophyte in both groups, being isolated from 71% of infected miners and 77% of infected outpatients. The incidence of atopy in the outpatients, but not the miners, was significantly higher in individuals with T rubrum infections than in control groups. An analysis of the data from both groups suggests that in the coal miners, in whom there is a high risk of endemic dermatophytosis, susceptibility factors such as atopy are of less importance than in patients seen in a dermatological outpatient clinic in whom the risk of exposure to other sources of dermatophytosis is low.

Conidiogenesis in Petriellidium boydii (Pseudallescheria boydii). A light and electron microscope study

Slide cultures of the type strain of P. boydii Shear, showed percurrent production of conidia by light microscopy over a period of several hours. Scanning and transmission electron microscopy were used to examine the conidiogenesis. The conidiogenous cells developed annular ridges rather than typical annellophoric scars. Evidence that these ridges represented sequential spore production was shown by T.E.M. in the form of a discontinuity of the outer conidiophore wall at the widest point of each ridge.