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Biomedical subjects

M Nicholas

Publications and source records attributed to M Nicholas.

At least 19 recordsLinked to original sources
PubMed2000

Collective oscillations of fresh and salt water bubble plumes

Bubble plumes of various void fractions and sizes were produced by varying the flow velocity of a water jet impinging normally on a water surface. The bubbles entrained at the surface were carried downwards by the fluid flow to depths ranging from 33 to 65 cm, and formed roughly cylindrical plumes with diameters ranging from 12 to 27 cm. The acoustic emissions from the plumes were recorded onto digital audio tape using a hydrophone placed outside the cloud at distances ranging from 50 cm to 16.0 m. Closeup video images of the individual bubbles within the plume were also taken in order to gain knowledge of the bubble size distributions. The experiments were performed in both fresh-water and salt-water environments. The fresh-water clouds emitted sounds with a modal structure that was significantly different from that produced by the salt-water clouds. Furthermore, the smaller bubbles present in the salt-water clouds have a fundamental effect on the amplification of turbulence noise, generating sound at significant levels for frequencies up to several hundred Hertz.

Journal Article↗
PubMed2000

The matched-phase coherent multi-frequency matched-field processor

Coherent multi-frequency matched-field processing is investigated using a matched-phase coherent matched-field processor. Its main difference from previous coherent processors is that the relative phases of the Fourier components contained within the recorded signal are not assumed to be known a priori. Rather they are considered free parameters that can be determined using a global functional minimization algorithm. Additionally, this processor uses only the cross-frequency terms, making it less susceptible to the detrimental effects of ambient noise; in one example, this processor shows a five decibel improvement over a similar coherent processor. Along with its increased sensitivity with respect to the broadcast source levels, this coherent processor exhibits superior range resolution as compared with multi-frequency incoherent processors, due to the cross-frequency interference of the vertical eigenmodes. Within this work we explore the efficacy of the algorithms used to determine the relative phases along with the performance of the matched-phase coherent processor itself, performed within the context of data collected during an event from the SWellEx-96 experiment. Performance comparisons between this processor, an incoherent processor, and another coherent processor are demonstrated using this data set.

Journal Article↗
PubMed1999

Advantages of heterogeneous therapy groups in the psychotherapy of the traumatically abused: treating the problem as well as the person.

The authors combine a social-constructionist perspective with a psychodynamic one in discussing the problem of trauma and its treatment. They argue that effective treatment of traumatic physical, sexual, and psychological abuse must do more than alleviate the pain of the sufferer. Factors that cause and perpetuate abuse must be addressed by the abused person in conjunction with other nontraumatized persons who may have been abusive or passive in the face of abuse. An argument is made for heterogeneous therapy groups as a context for this to occur.

Adult↗
PubMed1999

Verb naming in normal aging.

Few studies have examined verb naming in normal aging, although decline in the ability to name nouns has been well documented. In this study, we examined longitudinal performance on the Action Naming Test (ANT), a confrontation naming test for verbs. The purpose of this study was to confirm the verb naming deficit associated with aging, which was previously seen only in cross-sectional studies, and to provide additional normative data on verb naming ability that may prove useful to studies on verb naming in populations with brain dysfunction. Sixty-six healthy men and women aged 30 to 79 were each tested with the ANT 3 times over a 7-year span. ANT performance showed a significant decline over time for all participants except the youngest group. Longitudinal methodology supports the conclusion that this finding of a decline in verb naming ability arises from true age-related changes and not from cohort differences.

Adult↗
PubMed1998

Lesion site patterns in severe, nonverbal aphasia to predict outcome with a computer-assisted treatment program.

OBJECTIVE: To test whether lesion site patterns in patients with chronic, severe aphasia who have no meaningful spontaneous speech are predictive of outcome following treatment with a nonverbal, icon-based computer-assisted visual communication (C-ViC) program. DESIGN: Retrospective study in which computed tomographic scans performed 3 months after onset of stroke and aphasia test scores obtained before C-ViC therapy were reviewed for patients after receiving C-ViC treatment. SETTING: A neurology department and speech pathology service of a Department of Veterans Affairs medical center and a university aphasia research center. PATIENTS: Seventeen patients with stroke and severe aphasia who began treatment with C-ViC from 3 months to 10 years after onset of stroke. MAIN OUTCOME MEASURE: Level of ability to use C-ViC on a personal computer to communicate. RESULTS: All patients with bilateral lesions failed to learn C-ViC. For patients with unilateral left hemisphere lesion sites, statistical analyses accurately discriminated between those who could initiate communication with C-ViC from those who were only able to answer directed questions. The critical lesion areas involved temporal lobe structures (Wernicke cortical area and the subcortical temporal isthmus), supraventricular frontal lobe structures (supplementary motor area or cingulate gyrus 24), and the subcortical medial subcallosal fasciculus, deep to the Broca area. Specific lesion sites were also identified for appropriate candidacy for C-ViC. CONCLUSIONS: Lesion site patterns on computed tomographic scans are helpful to define candidacy for C-ViC training, and to predict outcome level. A practical method is presented for clinical application of these lesion site results in combination with aphasia test scores.

Adult↗
PubMed1996

On the nature of naming errors in aging and dementia: a study of semantic relatedness.

This study investigated the nature of naming errors produced on the Boston Naming Test by patients with mild and moderate Alzheimer's disease (AD) and elderly and young controls, using a newly devised scoring system. This new approach involved ratings of error responses on a scale of semantic relatedness to the target name. Error responses of both mild and moderate AD subjects were no less semantically related to target names than were responses of age- and education-matched controls. We conclude that some available evidence of semantic loss in AD may be an artifact of the methodology chosen for evaluating naming errors.

Adult↗
PubMed1995

Drawing to communicate: a case report of an adult with global aphasia.

Treatment for adults with global aphasia has typically involved the use of verbal treatment methods or alternative communication techniques including communication boards, word lists and notebooks. However, many adults with aphasia are unable to communicate verbally and alternative communication techniques can be limited, as a result of the restricted number and type of concepts that can be adequately depicted and expressed. Another viable means of communication for the globally aphasic adult is drawing. However, few individuals with severe aphasia initiate communication through this modality without specific training. In this case report we present several successful treatment methods that were used to train an adult with global aphasia to communicate more effectively through drawing. Several of his drawings are presented to illustrate the results of training in the use of drawing as an alternative means of communication.

Aphasia↗
PubMed1988

Emotional and non-emotional facial behaviour in patients with unilateral brain damage.

Aspects of emotional facial expression (responsivity, appropriateness, intensity) were examined in brain-damaged adults with right or left hemisphere cerebrovascular lesions and in normal controls. Subjects were videotaped during experimental procedures designed to elicit emotional facial expression and non-emotional facial movement (paralysis, mobility, praxis). On tasks of emotional facial expression, patients with right hemisphere pathology were less responsive and less appropriate than patients with left hemisphere pathology or normal controls. These results corroborate other research findings that the right cerebral hemisphere is dominant for the expression of facial emotion. Both brain-damaged groups had substantial facial paralysis and impairment in muscular mobility on the hemiface contralateral to site of lesion, and the left brain-damaged group had bucco-facial apraxia. Performance measures of emotional expression and non-emotional movement were uncorrelated, suggesting a dissociation between these two systems of facial behaviour.

Apraxias↗
PubMed1987

Effect of emotional context on bucco-facial apraxia.

Patients with left- and right-hemisphere cerebrovascular pathology and normal adult controls were videotaped while executing tasks of bucco-facial praxis in emotional and nonemotional conditions. Each practic movement was assessed for accuracy and motor execution. Left-brain-damaged patients were significantly impaired on these tasks relative to right-damaged patients and controls. When emotional context was provided, apractic performance improved significantly.

Apraxias↗
PubMed1986

The expression and perception of facial emotion in brain-damaged patients.

This study examined the expression and perception of facial emotion in patients with unilateral cerebrovascular pathology. Subjects were 12 right brain-damaged (RBD), 15 left brain-damaged (LBD) aphasic, and 16 normal control (NC) right-handed males. Expressions were elicited during posed and spontaneous conditions. Both positive and negative emotions were studied. RBDs were significantly impaired, relative to LBDs and NCs, in expressing and perceiving facial emotion. There were no group differences as a function of condition, but there were differences as a function of emotional valence. Qualitative performance differences also were observed. There was no evidence that the ability to produce a particular emotion was related to the ability to identify the same emotion. Overall, these findings support the notion that the right cerebral hemisphere is dominant for expressing and perceiving facial emotion.

Adult↗
PubMed1985

Channels of emotional expression in patients with unilateral brain damage.

The contribution of facial, intonational, and speech channels to spontaneous emotional expression was examined in right brain-damaged (RBD), left brain-damaged (LBD), and normal control (NC) subjects. Subjects were videotaped while viewing and responding to a series of emotionally laden slides; the videotapes were then rated for the three channels of communication. Overall, RBDs used facial expression and intonation less frequently than the other two groups. When the speech output channel was analyzed, oral expression of feelings in the RBDs, relative to the LBDs and NCs, was less appropriate, more propositional than prosodic, and more descriptive than affective. When the ratings for the three channels of communication were examined, facial expression and intonation were significantly correlated for all subjects.

Affect↗
PubMed1985

Lexical retrieval in healthy aging.

Lexical retrieval for common nouns and verbs was measured using 2 picture naming tests in 162 healthy female and male subjects aged 30 to 79 years. Responses were scored for correctness, responsivity to cueing, and response type. The ability to name both word types declined with age, especially after age 70 in healthy subjects. More errors were made on object names than action names, especially for older subjects. Subjects of all ages were equally able to utilize phonemic cues. With increasing age subjects produced more circumlocutions and fewer semantic errors. Response type difference need not reflect qualitative differences in lexical retrieval; rather, they reflect the quantitatively greater difficulty of the task for healthy older people as compared to younger adults. The naming difficulty for healthy aging, we conclude, is at the label retrieval stage.

Adult↗
PubMed1985

On comprehension across the adult lifespan.

To test whether healthy elderly subjects develop language comprehension strategies to compensate for decreases in pure-tone audition, we tested 128 healthy subjects aged 30-79 on two tasks: (1) Comprehension materials from the Boston Diagnostic Aphasia Examination (Goodglass and Kaplan, 1972) presented over babble noise with and without the speaker's face visible; and (2) the Kalikow et al. (1977) Speech Perception in Noise test, which assesses the effect of semantic predictability on sentence-final word intelligibility. Whereas, as predicted, overall performance decreased with advancing age, it appeared, unexpectedly, that older and younger adults were equally affected by the absence of visual input and the absence of semantic predictability.

Adult↗
PubMed1985

Empty speech in Alzheimer's disease and fluent aphasia.

Fourteen measures of empty speech during a picture description task were examined in four subject groups--patients with Alzheimer's dementia, Wernicke's aphasias, anomic aphasias, and normal controls--to discover if these groups could be distinguished on the basis of their discourse. Patients with Alzheimer's dementia were distinguished from patients with Wernicke's aphasia by producing more empty phrases and conjunctions, whereas patients with Wernicke's aphasia produced more neologisms, and verbal and literal paraphasias. The demented patients shared many empty speech characteristics with patients with anomic aphasia. Naming deficits, as measured by confrontation naming tasks, did not correlate with empty discourse production. Our findings may be useful clinically for distinguishing these different patient groups.

Adult↗
PubMed1984

Non-consultant peripheral clinics: a new approach to diabetic care.

A system of non-consultant peripheral clinics (NCPCs) established on the Isle of Wight is described. For the first phase of the study 182 diabetics attending the consultant clinic were allocated to the appropriate peripheral clinic (group 1). In the second phase, 152 new referrals were prospectively allocated between the consultant and appropriate peripheral clinics (group 2). Evaluation was made of the patients' random blood sugar and glycosylated haemoglobin. The savings in cost and time to patients resulted in over 90% of patients preferring the peripheral clinics. NCPCs are discussed in relation to hospital-based clinics and to other alternative systems of care. It is concluded that NCPCs could be incorporated into the diabetic service in other regions in the United Kingdom with advantages to diabetics and hospital services alike. These peripheral clinics are suited to all types of diabetics and perhaps the only clinical restriction is the desirability for metabolic deterioration to be managed by a consultant clinic until the patient is satisfactory.

Adolescent↗