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Biomedical subjects

M A Pitt

Publications and source records attributed to M A Pitt.

At least 37 records · Page 2Linked to original sources
PubMed1995

Evidence for a central representation of instrument timbre.

An information processing account of perception seeks to delineate the stages of processing through which a stimulus passes and determine the properties of the representation at each stage. Research in phonetic perception has identified two stages, the second of which is thought to encode abstract acoustic attributes of sounds. The present study provided a further test of this proposal by assessing whether nonphonetic stimuli could yield results similar to those obtained with phonetic stimuli. Five selective adaptation experiments were carried out with a trumpet-piano timbre continuum. Two manipulations were used to measure abstract encoding: cross-ear presentation of adaptor and test series, and the use of adaptors that were acoustically different from the continuum end-points. The results provide evidence for an abstract representation of timbre. The similarity of the findings to those in the phonetic adaptation literature is discussed.

Adult↗
PubMed1994

Leishmaniasis of the tongue treated with liposomal amphotericin B.

A 66-year-old man, immunosuppressed because of a lymphoma and with severe ischaemic heart disease and proteinuria, presented with a swelling on the tongue due to leishmaniasis. His travel history suggested that he had acquired the infection in the Mediterranean area some years earlier. He was treated with liposomal amphotericin B for 21 days and made a good recovery despite a temporary deterioration in renal function. Oral lesions are a rare manifestation of Old World leishmaniasis. Liposomal amphotericin B is a novel treatment that may be well tolerated when there is concern about the toxicity of more established drugs.

Aged↗
PubMed1994

Perception of pitch and timbre by musically trained and untrained listeners.

In 2 experiments the author investigated how musicians and nonmusicians differentially perceive the dimensions of pitch and timbre. A categorization task was used in Experiment 1 to assess Ss' ability to identify how 2 consecutively presented tones changed along these dimensions. A speeded classification task was used in Experiment 2 to measure Ss' ability to ignore or take advantage of information in 1 dimension while attending to the other. The 2 groups differed in the degree to which variation along the dimensions influenced responses. Timbre variation affected nonmusicians' judgments of pitch more than the reverse. Musicians showed no such asymmetry.

Acoustic Stimulation↗
PubMed1993

An empirical and meta-analytic evaluation of the phoneme identification task.

Recent studies that used Ganong's (1980) identification task have produced discrepant results. The present study sought to resolve these discrepancies by examining the influence of methodological factors on phoneme identification and differences in data analysis techniques. Three factors were examined across 2 experiments: position of target phoneme, phonetic contrast, and 2 task conditions in which stimulus quality (S/N ratio) or cognitive load varied. A meta-analysis was then performed on the results from all identification studies, including the present one, in an effort to obtain additional insight on factors that influence the task. The experiments and meta-analysis identified the importance of several methodological factors in affecting identification, most notably position of the target phoneme.

Adult↗
PubMed1993

Auditory recency in immediate memory.

Six experiments investigated the locus of the recency effect in immediate serial recall. Previous research has shown much larger recency for speech as compared to non-speech sounds. We compared two hypotheses: (1) speech sounds are processed differently from non-speech sounds (e.g. Liberman & Mattingly, 1985); and (2) speech sounds are more familiar and more discriminable than non-speech sounds (e.g. Nairne, 1988, 1990). In Experiments 1 and 2 we determined that merely varying the label given to the sets of stimuli (speech or non-speech) had no effect on recency or overall recall. We varied the familiarity of the stimuli by using highly trained musicians as subjects (Experiments 3 and 4) and by instructing subjects to attend to an unpracticed dimension of speech (Experiment 6). Discriminability was manipulated by varying the acoustic complexity of the stimuli (Experiments 3, 5, and 6) or the pitch distance between the stimuli (Experiment 4). Although manipulations of discriminability and familiarity affected overall level of recall greatly, in no case did discriminability or familiarity alone significantly enhance recency. What seems to make a difference in the occurrence of convincing recency is whether the items being remembered are undegraded speech sounds.

Adult↗
PubMed1993

The nature of atypical multinucleated stromal cells: a study of 37 cases from different sites.

The morphology, immunophenotype and ultrastructure of atypical multinucleated stromal cells in 37 specimens from different anatomical sites were compared. Overall, cellular morphology was similar between sites but nuclear features, immunophenotype and ultrastructure varied and reflected that of adjacent normal mononuclear stromal cells. It is concluded that the atypical multinucleated stromal cells represent a reactive change in the indigenous stromal cells. In all the cases mast cells were seen as a prominent component of the inflammatory infiltrate and many of them were intimately related to the atypical stromal cells. It is suggested that reactive stromal cell changes may relate to an interaction with mast cells.

Cell Nucleus↗
PubMed1993

Multinucleated stromal giant cells of the colonic lamina propria in ulcerative colitis.

Multinucleated stromal giant cells were seen in the colonic mucosa in biopsy specimens from two patients with long-standing quiescent ulcerative colitis. Similar cells have been described at other sites associated with chronic inflammation, including the lower female genital tract, bladder and anus. The immunophenotype of the cells in the colonic mucosa suggested that they had originated from fibroblasts rather than histiocytes, in common with cells seen at other sites of inflammation. These examples lend support to the concept of there being a reactive morphological change possibly related to interaction with mast cells. These multinucleated giant cells are distinct from histiocytic giant cells and should not be confused with them.

Aged↗
PubMed1992

The role of spectral and dynamic cues in imagery for musical timbre.

The musical quality of timbre is based on both spectral and dynamic acoustic cues. Four 2-part experiments examined whether these properties are represented in the mental image of a musical timbre. Experiment 1 established that imagery occurs for timbre variations within a single musical instrument, using plucked and bowed tones from a cello. Experiments 2 and 3 used synthetic stimuli that varied in either spectral or dynamic properties only, to investigate imagery with strict acoustic control over the stimuli. Experiment 4 explored whether the dimension of loudness is stored in an auditory image. Spectral properties appear to play a much larger role than dynamic properties in imagery for musical timbre.

Adult↗
PubMed1992

The distribution of type IV collagen in invasive carcinoma of the uterine cervix.

The presence of type IV collagen at the tumour/stromal interface of invasive carcinoma of the cervix was evaluated in 60 cases. It was assessed semi-quantitatively according to its staining characteristics, and expressed as: thick, with or without minimal discontinuity; thin, with or without moderate discontinuity; fragmentary or absent. In each case the tumour type was identified, the differentiation, growth pattern and peritumoural inflammatory infiltrate was graded and lymph node status established. There was, overall, a significant correlation between a paucity of type IV collagen and a poorer prognosis and an infiltrating growth pattern. There was a highly significant correlation for adenocarcinomas in relation to poor outcome, infiltrating growth pattern and lymph node metastases. By contrast, no statistically significant correlation was found between paucity of type IV collagen and the other parameters for either squamous or adenosquamous carcinomas. The presence of absence of type IV collagen may be a useful prognostic marker, particularly for adenocarcinomas, and may play a part in the invasive and metastatic process.

Adenocarcinoma↗
PubMed1992

Oligodendroglioma of the fourth ventricle with intracranial and spinal oligodendrogliomatosis: a case report.

We report a case of oligodendroglioma of the fourth ventricle complicated by disseminated intracranial and spinal oligodendrogliomatosis. This is further evidence that primary oligodendrogliomas arising in close proximity to the cerebrospinal pathway have a predilection for spontaneous dissemination. This condition should be considered in the differential diagnosis of hydrocephalus and myelopathy.

Adolescent↗
PubMed1990

The use of rhythm in attending to speech.

Three experiments examined attentional allocation during speech processing to determine whether listeners capitalize on the rhythmic nature of speech and attend more closely to stressed than to unstressed syllables. Ss performed a phoneme monitoring task in which the target phoneme occurred on a syllable that was either predicted to be stressed or unstressed by the context preceding the target word. Stimuli were digitally edited to eliminate the local acoustic correlates of stress. A sentential context and a context composed of word lists, in which all the words had the same stress pattern, were used. In both cases, the results suggest that attention may be preferentially allocated to stressed syllables during speech processing. However, a normal sentence context may not provide strong predictive cues to lexical stress, limiting the use of the attentional focus.

Adult↗
PubMed1984

The migration of lymphocytes across specialized vascular endothelium: VIII. Physical and chemical conditions influencing the surface morphology of lymphocytes and their ability to enter lymph nodes.

The introductory review amplifies the finding that simply holding lymphocytes in vitro reversibly compromises their ability to enter lymph nodes from the blood, although entry into the spleen is unaffected. The differential migration of T and B lymphocytes from the blood, lymphocyte traffic in athymic rats, and the secretion of a sulphated glycoconjugate by high endothelial cells in lymph nodes are also discussed. Original data are presented concerning the effects of varying the conditions under which lymphocytes are held in vitro (time, temperature, medium, centrifugation) on their ability to enter lymph nodes and also on their surface morphology. In general, conditions that reduced the number of microvilli and induced surface blebbing also tended to affect the delicate function of crossing specialized vascular endothelium; but there was no simple relationship between morphology and migratory behavior. The localization of lymphocytes to the bone marrow was augmented by holding them in vitro, and this effect was greater after holding at room temperature (RT) than at 0 degree C, in contrast to impaired entry into lymph nodes. Small amounts of heparin (10 units) injected along with lymphocytes significantly reduced early localization in lymph nodes. These findings have practical implications for the design of lymphocyte traffic experiments and are relevant to the mechanism of lymphocyte attachment to vascular endothelium, since the well-known effect of trypsinizing lymphocytes can be reproduced by maintenance in vitro.

Animals↗
PubMed1977

Interaction of molybdate with copper(II)-histidine.

Molybdate and copper(II)-histidine form an insoluble complex of empirical formula Cu2(His)3(MoO4)2(H2O)2ESR-spectroscopy indicated that the complex had tetragonal symmetry. IR-spectroscopy showed the presence of a carboxylate anion and suggested that the molybdate ion formed an ammonium-type salt with the nitrogens of the imidazole. The complex did not form following dissociation of the protonated imidazole (above a pH of approximately 6).

Chemical Phenomena↗
PubMed1976

Molybdenum toxicity: interactions between copper, molybdenum and sulphate.

Molybdenum toxicity and the interactions between copper, molybdenum and sulphate are reviewed. The main signs of molybdenum poisoning are poor growth and anaemia (rat, chick, rabbit, cattle and sheep), anorexia (rat), diarrhoea and achromotrichia (cattle and sheep), joint and bone deformities (rat, rabbit, cattle), central nervous system degeneration and loss of crimp in wool (sheep). The following topics are discussed: (1) The effect of sulphate and sulphur compounds on molybdenum toxicity. (2) The effect of molybdenum on tissue copper levels. (3) The effect of molybdenum on the distribution of copper in plasma. (4) The effect of molybdenum on uptake and excretion of copper. (5) The possible existence of copper(II) molybdate in vivo. (6) The influence of molybdenum on sulphide production by ruminal micro-organisms. (7) Competition between molybdenum and sulphate in intestinal transport. (8) Interaction of sulphur with copper in vivo. (9) The possible involvement of molybdenum in gout and multiple sclerosis in humans.

Animals↗