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R H Wilson

Publications and source records attributed to R H Wilson.

At least 37 records · Page 2Linked to original sources
PubMed1999

Influence of hospital and clinician workload on survival from colorectal cancer: cohort study.

OBJECTIVE: To determine whether clinician or hospital caseload affects mortality from colorectal cancer. DESIGN: Cohort study of cases ascertained between 1990 and 1994 by a region-wide colorectal cancer register. OUTCOME MEASURES: Mortality within a median follow up period of 54 months after diagnosis. RESULTS: Of the 3217 new patients registered over the period, 1512 (48%) died before 31 December 1996. Strong predictors of survival both in a logistic regression (fixed follow up) and in a Cox's proportional hazards model (variable follow up) were Duke's stage, the degree of tumour differentiation, whether the liver was deemed clear of cancer by the surgeon at operation, and the type of intervention (elective or emergency and curative or palliative intent). In a multilevel model, surgeon's caseload had no significant effect on mortality at 2 years. Hospital workload, however, had a significant impact on survival. The odds ratio for death within 2 years for cases managed in a hospital with a caseload of between 33 and 46 cases per year, 47 and 54 cases per year, and >/=55 cases per year (compared to one with </=23 cases per year) were respectively 1.48 (95% confidence interval 1.03 to 2.13), 1.52 (1.08 to 2.13), and 1.18 (0.83 to 1.68). CONCLUSIONS: There was no detectable caseload effect for surgeons managing colorectal cancer, but survival of patients treated in hospitals with caseloads above 33 cases per year was slightly worse than for those treated in hospitals with fewer caseloads. Imprecise measurement of clinician specific "events rates" and the lack of routinely collected case mix data present major challenges for clinical audit and governance in the years ahead.

Adult↗
PubMed1999

Mid-infrared spectroscopy and chemometrics for the authentication of meat products.

Mid-infrared (MIR) spectroscopy is used to address certain issues connected with the authentication of beef and ox kidney and liver: is it possible to distinguish muscle from offal tissue; does the condition, cut of meat, or type of offal influence the distinction; can pure minced beef be distinguished from that adulterated with offal? Using partial least squares (PLS) and canonical variate analysis, predictive models are developed to identify MIR spectra of beef, kidney, and liver. Using modified SIMCA, the pure beef specimens are modeled as a single class; this model identifies spectra of unadulterated beef as such, with an acceptable error rate, while rejecting spectra of specimens containing 10-100% w/w kidney or liver. Finally, PLS regressions are performed to quantify the amount of added offal. The prediction errors obtained (+/-4.8 and +/-4.0% w/w, respectively, for the kidney and liver calibrations) are commensurate with the detection limits suggested by the SIMCA analysis.

Animals↗
PubMed1999

Factors affecting the release of flavor encapsulated in carbohydrate matrixes.

The effects of water content and temperature variation on the release of flavor components into the headspace over flavors, encapsulated by an extrusion process, in low water content carbohydrate matrixes is studied. The largest amounts of release occurred when the matrix was above its glass transition temperature, whether this was due to increased water content or elevated temperature. Under these conditions up to 70% of the sucrose in the matrix crystallized over a period of 10 days, as quantified using Fourier transform Raman spectroscopy. Smaller amounts of headspace release occurred when the water content of the encapsulated flavor system was decreased from 3. 5 to 3.1% w/w. Small amounts of release occurred from the "as prepared" materials, which were associated with the presence of small amounts of unencapsulated flavor oil with direct access to the headspace. It was concluded that release due to matrix permeability was relatively slow as compared with the above mechanisms.

Carbohydrates↗
PubMed1999

Psychometrically equivalent spondaic words spoken by a female speaker.

Several studies demonstrate that thresholds for the individual CID W-1 spondaic words peaked at 0 vu are not equivalent. The purpose of this study was to equate the spondaic word thresholds psychometrically. Two studies were performed on 2 groups of 20 listeners with normal hearing. In Experiment 1, psychometric functions were established for the 36 spondaic words spoken by a male (original recording) and female speaker. Based on the threshold data from Experiment 1, the words spoken by the female speaker were adjusted digitally in level to produce equal thresholds (equal intelligibility). In Experiment 2, psychometric functions then were established for the 36 spondaic words adjusted in level. The mean thresholds for the 2 experiments were the same (0.5 dB HL; ANSI, 1996), but the standard deviations for the word thresholds in Experiment 2 (0.7 dB) were significantly smaller than the standard deviations in Experiment 1 (1.6 dB). Both versions of the spondaic words spoken by the female speaker are included on the Speech Recognition and Identification Materials (Disc 2.0) compact disc.

Auditory Threshold↗
PubMed1999

Word recognition performance for Northwestern University Auditory Test No. 6 word lists in quiet and in competing message.

Word recognition norms were determined for the Northwestern University Auditory Test No. 6 (NU-6) released on the Department of Veterans Affairs (VA) Disc 1.1. Word recognition performance (in quiet and in competing message) was measured at 12 presentation levels for 24 young adults with normal hearing. Test-retest reliability also was evaluated. Word recognition scores for VA Disc 1.1 were generally higher than those reported for VA Disc 1.0. The differences in NU-6 scores across disc versions, however, were small and unlikely to affect clinical decisions based on word recognition tests. Score differences on test-retest for the VA Disc 1.1 version of the NU-6 with a competing message background also were small and unlikely to affect clinical outcomes. Overall, based on comparisons of scores for the disc versions of the NU-6, it appears that the two different recordings can be used interchangeably for clinical applications.

Adolescent↗
PubMed1999

Stimulus length uncertainty with dichotic digit recognition.

Dichotic digit listening was made more difficult by interleaving one-, two-, three-, and four-pair digits within a test list in which the subjects did not know a priori the number of digit pairs presented on a given trial, thereby introducing listener uncertainty. Twenty right-handed (mean age = 26.8 years) and 20 left-handed adults (mean age = 24.0) with normal hearing and 40 right-handed adults in the 60- to 75-years age range (mean age = 67.2) with mild-to-moderate sensorineural hearing loss were evaluated. Compared to traditional paradigms, the uncertainty of stimulus length (one, two, three, or four pairs) reduced overall recognition performance on stimuli presented to both ears of all groups, but the reduction was more pronounced for the left ear than for the right ear. The recognition performance of the right-handed subjects was more homogeneous than the performance of the left-handed subjects. In comparison to the young subjects, the 60- to 75-year-old group had substantially reduced recognition performance.

Adult↗
PubMed1998

A rapid method to screen for cell-wall mutants using discriminant analysis of Fourier transform infrared spectra.

We have developed a rapid method to screen large numbers of mutant plants for a broad range of cell wall phenotypes using Fourier transform infrared (FTIR) microspectroscopy of leaves. We established and validated a model that can discriminate between the leaves of wild-type and a previously defined set of cell-wall mutants of Arabidopsis. Exploratory principal component analysis indicated that mutants deficient in different cell-wall sugars can be distinguished from each other. Discrimination of cell-wall mutants from wild-type was independent of variability in starch content or additional unrelated mutations that might be present in a heavily mutagenised population. We then developed an analysis of FTIR spectra of leaves obtained from over 1000 mutagenised flax plants, and selected 59 plants whose spectral variation from wild-type was significantly out of the range of a wild-type population, determined by Mahalanobis distance. Cell wall sugars from the leaves of selected putative mutants were assayed by gas chromatography-mass spectrometry and 42 showed significant differences in neutral sugar composition. The FTIR spectra indicated that six of the remaining 17 plants have altered ester or protein content. We conclude that linear discriminant analysis of FTIR spectra is a robust method to identify a broad range of structural and architectural alterations in cell walls, appearing as a consequence of developmental regulation, environmental adaptation or genetic modification.

Arabidopsis↗
PubMed1998

Development of suprathreshold word recognition test for Russian-speaking patients.

This paper describes the development and normalization of a computerized word recognition test for speakers of the Russian language: the Russian Picture Identification Task (RPIT). The test uses a picture-pointing response, in which a patient selects, on a computer screen, a picture corresponding to a target word from a foil of four rhyming alternatives. The auditory portion of the test is recorded digitally and is recalled from a clinician's computer by clicking a mouse on the English translation of the target word. Thus, an English-speaking clinician can assess reliably word recognition abilities of Russian-speaking patients-a task that has become important in view of the recent surge of immigration from the former Soviet Union. Normative performance of normal-hearing native speakers of Russian was obtained in oral response conditions and picture-pointing conditions intended for clinical use. Psychometric functions provide norms for clinical decision making. Error patterns, individual confusions, and cognitive aspects of the experiment are discussed.

Adult↗
PubMed1997

Enigmatic phylogeny of skuas (Aves:Stercorariidae)

Multiple sources of evidence show that the skuas (Aves:Stercorariidae) are a monophyletic group, closely related to gulls (Laridae. On morphological and behavioural evidence the Stercorariidae are divided into two widely divergent genera, Catharacta and Stercorarius, consistent with observed levels of nuclear and mitochondrial gene divergence. Catharacta skuas are large-bodied and with one exception breed in the Southern Hemisphere. Stercorarius skuas otherwise known as jaegers) are smaller bodied and breed exclusively in the Northern Hemisphere. Evidence from both mitochondrial and nuclear genomes and from ectoparasitic lice (Insecta:Phthiraptera) shows that the Pomarine skua, S. pomarinus, which has been recognized as being somewhat intermediate in certain morphological and behavioural characteristics, is much more closely related to species in the genus Catharacta, especially to the Northern Hemisphere-breeding Great skua, C. skua, than it is to the other two Stercorarius skuas, the Arctic skua, S. parasiticus and the Longtailed skua, S. longicaudus. Three possible explanations that might account for this discordant aspect of skua phylogeny are explored. These involve (i) the segregation of ancestral polymorphism, (ii) convergent evolution of morphology and behaviour or (iii) inter-generic hybridization. The available evidence from both nuclear and mitochondrial genomes does not exclude any of these hypotheses. Thus, resolution of this enigma of skua phylogeny awaits further work.

Animals↗
PubMed1997

Psychometric functions for the CID W-22 and NU Auditory Test No. 6. Materials spoken by the same speaker.

The equivalence was determined for the W-22 and NU No. 6 lists recorded with the same carrier phrase and by the same speaker (Auditec compact disc). For presentation, the lists were interleaved to form lists of 100 words. In Experiment 1, the materials were presented in quiet (0 to 30 dB HL) and in 60 dB SPL speech-spectrum noise (35 to 65 dB HL) at 5 dB intervals to 24 subjects with normal hearing. In Experiment 2, the materials were presented at two levels 10 dB apart to 24 subjects with sensorineural hearing loss. Recognition performance was on average 4 to 8% better on NU No. 6 materials than on the W-22 materials, a difference that was significant for both subject groups. The 2 to 4 dB differences are within the 5 dB steps typically used clinically and are not considered of clinical significance.

Adult↗
PubMed1997

Performance norms for the VA compact disc versions of CID W-22 (Hirsh) and PB-50 (Rush Hughes) word lists.

The purpose of this study was to establish normative articulation functions for the Hirsh recordings of the CID W-22 word lists and te Rush Hughes recordings of the PB-50 word lists as recorded on the VA compact disc. Twenty-four young adults with normal hearing listened to both sets of materials presented in quiet at 12 levels (0-56 dB HL). Presentation levels on average needed to be 10 dB higher for the PB-50 word lists to obtain word recognition performance scores equal to those for the W-22s. Maximum word recognition scores of 95 to 100 percent were obtained for the W-22s at lower presentation levels (> 40 dB HL), compared to 80 to 90 percent for the PB-50s at the maximum presentation level (56 dB HL). Mean slopes for the W-22 and PB-50 functions were 4.1 percent/dB and 1.9 percent/dB, respectively. Test-retest reliability was judged to be clinically appropriate for both sets of materials. Item analyses revealed a substantially skewed distribution toward easy items for the W-22 word lists compared to a more balanced distribution of item difficulty for the PB-50 lists. List equivalency was also judged to be clinically appropriate for the PB-50 word lists.

Adult↗
PubMed1996

Colorectal cell kinetics.

The assessment of cell proliferation in colorectal tissue may provide information with both prognostic and therapeutic implications. A variety of methods are available, including flow cytometric estimations of S phase fraction, immunohistochemical and autoradiographic visualization of exogenous and endogenous proliferation proteins, and morphological and stathmokinetic techniques. There is some correlation between Dukes stage and proliferation state features, and there is increased proliferative activity throughout the adenoma-carcinoma sequence. Data on cell proliferation rates are difficult to obtain. When correctly applied, the metaphase arrest technique remains the 'gold standard' of measuring proliferation, but its usefulness in clinical practice is limited. Recent studies have employed dual measurement flow cytometry and double labelling techniques to produce rate data.

Biomarkers↗
PubMed1996

Effect of step size on clinical and adaptive 2IFC procedures in quiet and in a noise background.

Audibility thresholds for a 1000-Hz sinusoid were measured with a standard clinical (CLIN) procedure and a two-interval, forced-choice (2IFC) adaptive procedure bracketing 79% correct. Both used 2- and 5-dB step sizes in quiet and in a continuous, broadband noise background. Clinical thresholds were from 2 to 4 dB higher than 2IFC thresholds, depending on the condition. Step size had a larger effect on the CLIN thresholds than the 2IFC thresholds. For the CLIN procedure, thresholds with a 2-dB step size were 1.4 dB lower than with a 5-dB step size. For the 2IFC procedure, thresholds with a 2-dB step size were 0.8 dB higher than with a 5-dB step size. Reliability, as measured by the intrasubject standard deviation, was better for the 2IFC than for the CLIN procedure and better in noise than in quiet. Reliability was unaffected by step size. Adding extra trials to the 2IFC adaptive track decreased the variability across threshold estimates, but more for the noise background than the quiet background. The efficiency of the 2IFC procedure was fairly constant across track length in noise, but decreased for longer track lengths in quiet. In both quiet and noise backgrounds, CLIN procedures were much more efficient than 2IFC procedures.

Adult↗
PubMed1996

Identification performance by right- and left-handed listeners on dichotic CV materials.

Normative data from 24 right-handed and 24 left-handed subjects were obtained for the dichotic consonant-vowel (CV) materials (pa, ta, ka, ba, da, and ga) recorded on the Veterans Affairs (VA) compact disc (CD) Tonal and Speech Materials for Auditory Perceptual Assessment, Disc 1.0. Identification performance by the two subject groups was significantly different. With the right-handed subjects, identification performances on the materials presented to the right ear (RE) were better than performances on the materials presented to the left ear (LE) by (1) 16.3 percent for simultaneous onsets (RE = 72.8%; LE = 56.5%), (2) 11.3 percent for the 90-msec right-ear lag (RE = 86.3%; LE = 75.0%), and (3) 8.7 percent for the 90-msec left-ear lag condition (RE = 85.8%; LE = 77.2%). In comparison to the right-handed subjects, the left-handed subjects exhibited a smaller right-ear advantage and more inter-subject variability. With the left-handed subjects, identification performances on the materials presented to the right ear also were better than performances on the materials presented to the left ear by (1) 1.7 percent for simultaneous onsets (RE = 62.9%; LE = 61.1%), (2) 2.8 percent for the 90-msec right-ear lag (RE = 75.0%; LE = 72.2%), and (3) 3.1 percent for the 90-msec left-ear lag condition (RE = 75.9%; LE = 72.9%). The results are similar to previous dichotic CV data and indicate that the CVs recorded on the VA-CD provide valid estimates of identification performance on the dichotic CV materials.

Adult↗
PubMed1996

Interactions of age, ear, and stimulus complexity on dichotic digit recognition.

The effect that the aging process has on recognition performance was studied using a hierarchy of 1-pair, 2-pair, 3-pair, and 4-pair dichotic digits (1, 2, 3, 4, 5, 6, 8, 9, and 10, male speaker). Two groups of right-handed subjects were studied: 20 adults < 30 years of age with normal hearing and 20 adults 60-75 years with mild-to-moderate hearing loss. Each of the multipaired sets contained the 72 possible 1-pair digit combinations in each presentation position with no digits repeated in a set. A three-way analysis of variance with repeated measures indicated three significant differences. First, as the complexity of the listening task increased from 1 pair to 2 pairs to 3 pairs to 4 pairs, recognition performance decreased systematically and significantly. The decreases in performance between the 1- and 4-paired conditions were larger for the left ear than for the right ear and were larger for the 60-75 years group than for the < 30 years group. Second, performance on the materials presented to the right ear was significantly better than performance on the materials presented to the left ear. Third, recognition performance by the < 30 years group was significantly better than recognition performance by the 60-75 years group. Recognition performance on the 1-pair condition was near maximum for both subject groups. Between the 1- and 4-paired conditions, recognition performance for materials presented to the left and right ears decreased 15.7 percent and 10.0 percent, respectively, in the < 30 years group and decreased 29.3 percent and 15.7 percent, respectively, in the 60-75 years group.

Adult↗