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D Kay

Publications and source records attributed to D Kay.

At least 19 recordsLinked to original sources
PubMed2003

Modelling faecal indicator concentrations in large rural catchments using land use and topographic data.

AIMS: To characterize and model spatial variations in faecal-indicator organism concentrations in watercourses draining a large rural catchment during the bathing season. METHODS AND RESULTS: Presumptive coliform (PC), presumptive Eschericia coli (PE) and presumptive enterococci (PEnt) concentrations were determined under base- and high-flow conditions at 24 monitoring points in the Rheidol/Ystwyth catchment, Wales. Relationships with land use and topographic variables within their 'subcatchments' were investigated. Geometric mean (GM) concentrations typically increase more than 10-fold at high flow. The proportion of improved pasture within subcatchments explains 81.6, 73.0 and 85.8%, respectively, of the variance in high-flow GM PC, PE and PEnt concentrations. Distributed modelling suggests that organisms derived from more distant parts of subcatchments may be lost through die-off and sedimentation along watercourses at base flow, although not at high flow. Reductions in concentrations are also evident downstream of reservoir impoundments. CONCLUSIONS: Large rural catchments may contribute substantially to faecal indicator loadings in coastal waters. Indicator concentrations can be modelled successfully using land use and topographic data. SIGNIFICANCE AND IMPACT OF THE STUDY: Development of a modelling approach that provides valuable insight into faecal indicator sources and the transport and survival of these organisms within large catchments.

Environmental Monitoring↗
PubMed2003

EMG amplitude in maximal and submaximal exercise is dependent on signal capture rate.

This study analysed the effect of different electromyographic (EMG) capture rates during maximal voluntary contraction, submaximal and maximal dynamic cycling activity on EMG amplitude and signal characteristics. Ten healthy subjects participated in this study. Peak power output (PPO) and maximal isometric force output (MVC) were measured, followed by a progressive cycle ride on a cycle ergometer. Electromyographic (EMG) data were simultaneously captured during the MVC and cycling activities at frequencies of 32, 64, 128, 256, 512, 1024 and 1984 Hz. Significant differences in amplitude were found (p < 0.01) between MVC, submaximal (SUB) and maximal cycling activities (PWATT) for all capture rates. Asymptote values for IEMG amplitude occurred at EMG capture rates of 1604 +/- 235.6 Hz during MVC, 503.1 +/- 236.2 Hz during PWATT and 326.2 +/- 105.4 Hz during SUB cycling activity and were significantly different (p < 0.01). No significant differences were found for force/EMG ratios between PWATT and MVC at 1984 Hz capture rates (3.8 +/- 1.7 N/V vs 2.5 +/- 0.9 N/V) while significant differences occurred at 32 Hz capture rate (6.2 +/- 3.8 vs 16.0 +/- 8.0; p < 0.01). Low correlations were found between EMG activity captured at 1984 Hz during PWATT and lean thigh volume (r = 0.36) and MVC (r = 0.32). Asymptote values found on this study suggest that data captured below 326 Hz for SUB, 503 Hz for PWATT and 1604 Hz for MVC are not reliable. Therefore apparatus capturing EMG data at low frequencies from these values cannot be used for quantitative data analyses.

Adult↗
PubMed2002

A reproducible and variable intensity cycling performance protocol for warm conditions.

This study was undertaken to assess the reproducibility of a variable intensitycycling protocol using subjects of varying abilities, under warm humid conditions. Eleven subjects (Age 21.4+/-2.6 years; VO2peak 3.30+/-0.9 l x min(-1); peak power 322.8+/-86.3 W; mean+/-SD) performed a 60 min cycling trial punctuated with six one-min "all-out" sprints at 10-min intervals on three occasions 5-14 days apart. Ambient temperature and relative humidity were set at 33+/-0.7 degrees C and 63+/-2.0%, respectively. Subjects used their own bicycle mounted to an electromagnetic trainer and were only permitted to monitor elapsed time and heart rate. Repeatability was assessed using the limits of agreement which were best between trials 2 and 3 where the distance cycled was -0.54 km below and 1.34 km above the distance cycled for trial 2. The co-efficient of variation (CV) for distance for three trials was 3.58%. For trials 1 and 2 the CV was 3.54% (r = 0.97, p< 0.001) decreasing to 1.34% (r = 0.99, p< 0.001) for trials 2 and 3. The intra-class correlation for three trials was 0.93. Distance for trial 1 (26.3+/-5.0 km; p< 0.05) was less than trials 2 (27.7+/-5.7 km) and 3 (28.1+/-5.6 km). It was concluded that repeatability for this performance protocol with cyclists of varying abilities In warm humid conditions was acceptable given at least one familiarisation trial. However, it is not yet known whether other protocols designed for moderate environments are applicable to less favorable conditions. Further studies are needed before results of treatment effects under differing ambient conditions can be fully understood and assigned appropriate significance.

Adult↗
PubMed2001

Detection of widespread fluids in the Tibetan crust by magnetotelluric studies.

Magnetotelluric exploration has shown that the middle and lower crust is anomalously conductive across most of the north-to-south width of the Tibetan plateau. The integrated conductivity (conductance) of the Tibetan crust ranges from 3000 to greater than 20,000 siemens. In contrast, stable continental regions typically exhibit conductances from 20 to 1000 siemens, averaging 100 siemens. Such pervasively high conductance suggests that partial melt and/or aqueous fluids are widespread within the Tibetan crust. In southern Tibet, the high-conductivity layer is at a depth of 15 to 20 kilometers and is probably due to partial melt and aqueous fluids in the crust. In northern Tibet, the conductive layer is at 30 to 40 kilometers and is due to partial melting. Zones of fluid may represent weaker areas that could accommodate deformation and lower crustal flow.

Journal Article↗
PubMed2001

Uncertainties in risk assessment for the determination of drinking water pollutant concentrations: Cryptosporidium case study.

There is a growing acknowledgement of the need to recognise uncertainties in the estimation of waterborne risks. In this paper, the strength of the science available to characterise Cryptosporidium risks in drinking water is investigated, in particular the determination of oocyst concentrations at various points in the chain of water supply. A recently developed scientific quality audit framework is used as a tool to guide this investigation. The framework systematically reveals the relatively greater strength of the science for the "upstream" elements (estimation of concentrations in environmental reservoirs) than for the "downstream" elements (concentrations in distribution). It is the downstream elements that have greater bearing on human health and public policy issues. It is noted that the adoption of new monitoring Regulations is likely to prompt action to strengthen knowledge of these downstream elements in the future.

Animals↗
PubMed2001

Relationships between microbial water quality and environmental conditions in coastal recreational waters: the Fylde coast, UK.

This paper explores ways in which the analysis of microbial data from routine compliance monitoring, in combination with basic environmental data, can provide insight into the factors affecting faecal-indicator organism concentrations in coastal waters. In the case study presented, eight designated bathing waters on the Fylde coast are continuing to exhibit unreliable compliance with the Imperative standards for total coliform (TC) and faecal coliform (FC) concentrations specified in the EU Bathing Water Directive (76/160/EEC), despite significant reductions in geometric mean concentrations following recent major investment in the sewerage infrastructure. Faecal streptococci (FS) concentrations have remained high and have not been improved by the new sewerage schemes. The results suggest that, prior to the schemes, higher bacterial concentrations were strongly associated with rainfall; and sewage sources were important for TC and FC, but less important for FS, which may have been more strongly affected by diffuse catchment sources. In the post-schemes period, catchment sources appear to be of greater significance; rainfall remains as a significant, though less important, predictor; and tide height at time of sampling, together with variables such as sunshine and the proportion of onshore winds (which affect the survival and movement of bacteria that have already entered the coastal waters), assume greater significance. The approach used here provides a cost-effective management tool for the exploratory investigation of any monitoring point that is failing to meet recreational water quality standards.

Environmental Monitoring↗
PubMed2001

Ageing is not associated with a decline in neuromuscular innervation or reduced specific force in men aged 20 and 50 years.

The exact mechanisms responsible for the decline in strength with age are yet to be completely elucidated. Three proposed mechanisms responsible for the detrimental effect of increasing age on strength include changes in muscle mass, specific force and/or neuromuscular innervation. Thus, the purpose of this investigation was to determine if the age-related reduction in peak isometric strength was primarily associated with changes in muscle cross-sectional area, neuromuscular innervation and/or specific force. The cross-sectional area of the knee extensor muscles (QCSA) was estimated in 13 younger men (YM; 20.8 +/- 1.6 years) and eight middle-aged men (MM; 53.8 +/- 4.2 years) prior to performing a series of four maximal voluntary isometric contractions on an isokinetic dynamometer at an angle of 60 degrees knee flexion. Peak force was determined and surface electromyography was sampled from the rectus femoris muscle during each maximal voluntary contraction. The cross-sectional area of the knee extensor muscles, peak force and integrated electromyography (IEMG) were significantly lower in the MM (P<0.01). However, when peak force and peak IEMG values were corrected for QCSA, there were no significant differences between age groups. These results suggest that the reduction in peak isometric force observed in the MM was primarily associated with quantitative changes in muscle mass, rather than reduced neuromuscular innervation or specific force. Therefore, preserving muscle mass through resistance training may significantly reduce the age-associated differences in peak strength and assist in promoting quality of life and functional independence in older adults.

Adult↗
PubMed2001

A review of the science behind drinking water standards for copper.

Copper is an essential element, being a vital component in several enzyme systems. Some intake, therefore, is necessary for human health. At high intakes, however, it can have toxic effects. This paper uses a quality audit framework to review the strength of the science underlying the setting of standards for copper in drinking water intended for human consumption. The two copper standards examined are the revised EU drinking water directive (98/83/EC) of 2 mg/l, based on WHO guidelines, and the USEPA treatment technique action level of 1.3 mg/l. Examination of these standards reveals that neither has a firm scientific basis, accordingly both are difficult to justify from a scientific standpoint, a situation that is worrying in both health and policy terms.

Copper↗
PubMed2000

A new disease-burden method for estimating the impact of outdoor air quality on human health.

Urban air quality is a serious problem, with an estimated 40 million people in Europe exposed to exceedences of existing WHO air-quality guidelines, with prospects of further declines in air quality due to projected growth in motor vehicle traffic. Air-quality management strategies, underpinned by legislation are attempting to combat this problem. To support such strategies, assessment of the costs and benefits of remedial measures is required, including an assessment of the impact of urban air quality on human health. This paper describes a disease burden estimation approach, developed to assess 'health gain' from recreational water quality improvement, and its application to urban air quality and incidence of respiratory disease. The method represents an improvement over existing disease-burden estimation techniques applied to air quality, in that by considering the probability density function of pollutant concentrations, improved estimates of exposure and hence disease burden, and also 'health gain' from air-quality improvement, are possible. Estimations of mortality advanced by fine particulate matter (PM10) are presented for five UK cities. Implications of the method for disease burden and air-quality standards are discussed. The utility of integrating the disease-burden assessment model with linked dynamic models of land-use, vehicle movement and pollutant dispersion, as a means to identify remedial strategic planning initiatives, is highlighted.

Air Pollutants↗
PubMed2000

Different neuromuscular recruitment patterns during eccentric, concentric and isometric contractions.

Aim. The purpose of this study was to determine the neuromuscular fatigue profiles during 100 s isometric (ISO), concentric (CON), and eccentric (ECC) activity.Methods. Twelve subjects (age 25.1+/-3.7 years, mass 70.1+/-8.2 kg, mean+/-SD) performed ISO, CON and ECC maximal voluntary contractions and 100 s endurance trials on an isokinetic dynamometer. Raw EMG data were recorded throughout each trial from the rectus femoris of the right limb. Corresponding data for integrated electromyography (IEMG), percentile frequency shifts (MPFS) and peak torque output were divided into five 5 s epochs and subsequently normalised with the first epoch being the reference point, in order to assess changes over time.Results. There were no significant differences between ECC, CON and ISO peak torque output (211+/-63 vs 169+/-41 vs 177+/-61 Nm; ECC, CON, ISO) and IEMG activity (280+/-143 vs 305+/-146 vs 287+/-143 mV; ECC, CON, ISO) during maximal contractions. Serial reductions in torque output were greatest in ISO in which torque output during the final epoch was 31+/-13% of initial values, similar to the final torque values in CON (58+/-15%), but significantly less than ECC (108.6+/-38.6%; P<0. 001) values. In CON and ECC, IEMG was maintained (95+/-27% and 93+/-21%; CON and ECC), whereas IEMG for ISO decreased to 38+/-13% of initial values. The greatest reduction in MPFS occurred in CON (69+/-10%) compared to ISO (78+/-9%; P<0.05) and ECC (93+/-6%; P<0.001).Conclusion. These data demonstrate distinct neuromuscular fatigue profiles for the different types of muscle contraction. Whereas eccentric activity was largely fatigue resistant, isometric and concentric contractions displayed different neuromuscular fatigue profiles.

Adult↗
PubMed2000

Parent reported allergy and anaphylaxis in 4173 South Australian children.

OBJECTIVES: To determine the prevalence of parent reported allergy and anaphylaxis in a sample of children and to investigate the first aid management of anaphylaxis in the schools and preschools that these children attend. METHODS: The study sample comprised 4173 South Australian children aged 3-17 years. Information was collected regarding parent-reported allergy and anaphylaxis. All children with known anaphylaxis were contacted and an attempt was made to contact those with reports of allergy to ascertain if these children had anaphylaxis. A telephone questionnaire was used to verify reports of anaphylaxis and determine the cause, severity and school first aid management of anaphylaxis. RESULTS: The rate of parent reported allergy and anaphylaxis was 7.3 and 0.59 per 100 children, respectively. Two-thirds of children with anaphylaxis did not have emergency medication available at school, an emergency action plan, or a teacher on site able to administer adrenaline for first aid use. CONCLUSIONS: Children attending preschool or school may have had a past history of anaphylaxis. Arrangements for first aid management of these children while in this environment are often inadequate.

Adolescent↗
PubMed2000

Fluid ingestion and exercise hyperthermia: implications for performance, thermoregulation, metabolism and the development of fatigue.

The development of fatigue during exercise and the subsequent onset of exhaustion occur earlier in the heat than in cooler environments. The underlying mechanisms responsible for the premature development of fatigue in the heat have yet to be clearly identified. However, the proposed mechanisms include metabolic, cardiovascular and central nervous system perturbations, together with an elevated core temperature. Fluid ingestion is one of three strategies that have been shown to be successful in enhancing the performance of endurance exercise in the heat, with the other interventions being precooling and acclimatization. However, like the development of fatigue in the heat, the mechanisms by which fluid ingestion allows for improved exercise performance remain unclear. We propose that fluid ingestion enhances exercise performance in the heat by increasing the heat storage capacity of the body. We suggest that the thermoregulatory, metabolic and cardiovascular alterations that occur as a result of this increased heat storage capacity contribute to performance enhancement when fluid is ingested during exercise heat stress.

Body Fluids↗
PubMed2000

Diagnosis and management of the lateralized tympanic membrane.

OBJECTIVE: Lateralization of the tympanic membrane (TM) is associated with significant morbidity. In a series of 14 patients, we make observations to illuminate this condition for the diagnosing and treating physician. STUDY DESIGN: Chart review of 14 consecutively treated patients. METHODS: We analyzed the presenting signs and symptoms, etiology, audiometric data, and operative findings of patients with a lateralized tympanic membrane (TM). RESULTS: The etiology was postsurgical in 13 patients (there were four aural atresia repairs and nine tympanoplasties), with 2 patients having had multiple previous surgeries. Presentation averaged more than 5 years after the latest surgery. Presenting symptoms included hearing loss in 10, tinnitus in 3, vertigo in 3, and otorrhea in 2 patients; 3 patients were nonsymptomatic at the time of presentation. The average air-bone gaps were 39 dB before treatment and 29 dB after treatment. Operative findings included cholesteatoma in six patients. Eight patients healed with the TM in the normal position; one had TM retraction, one had a TM perforation, and three had a recurrent lateralization. CONCLUSION: The lateralized TM is primarily, but not necessarily, a complication of otological surgery. It may be associated with considerable morbidity, including hearing loss and cholesteatoma. Patients may present several years after their surgery, occasionally as an incidental finding. Surgical repair is often necessary for significant underlying disease, but re-establishment of a normal TM can be challenging.

Adolescent↗
PubMed1999

Whole-body pre-cooling and heat storage during self-paced cycling performance in warm humid conditions.

The aim of this study was to establish the effect that pre-cooling the skin without a concomitant reduction in core temperature has on subsequent self-paced cycling performance under warm humid (31 degrees C and 60% relative humidity) conditions. Seven moderately trained males performed a 30 min self-paced cycling trial on two separate occasions. The conditions were counterbalanced as control or whole-body pre-cooling by water immersion so that resting skin temperature was reduced by approximately 5-6 degrees C. After pre-cooling, mean skin temperature was lower throughout exercise and rectal temperature was lower (P < 0.05) between 15 and 25 min of exercise. Consequently, heat storage increased (P < 0.003) from 84.0+/-8.8 W x m(-2) to 153+/-13.1 W x m(-2) (mean +/- s(mean)) after pre-cooling, while total body sweat fell from 1.7+/-0.1 l x h(-1) to 1.2+/-0.1 l h(-1) (P < 0.05). The distance cycled increased from 14.9+/-0.8 to 15.8+/-0.7 km (P < 0.05) after pre-cooling. The results indicate that skin pre-cooling in the absence of a reduced rectal temperature is effective in reducing thermal strain and increasing the distance cycled in 30 min under warm humid conditions.

Adolescent↗
PubMed1999

Evaluation of a training and diagnostic ultrasound service for general practitioners using narrowband ISDN.

We carried out a four-month pilot study of telemedicine for the delivery of training and diagnostic ultrasound services for general practitioners (GPs). Two health centres and a district general hospital were linked using ISDN (128 kbit/s) and PC-based videoconferencing units. Sixteen videoconferencing sessions were conducted, with 64 patients scanned over the ISDN link for a range of clinical conditions. Nine cases of pathology were demonstrated and confirmed by a consultant radiologist. A total of 229 images were transmitted using the store-and-forward facility, of which 194 (85%) images were of diagnostic quality and 35 (15%) were regarded as non-diagnostic. Allowing for sampling error, we would expect 79-89% of stored images to provide diagnostic information at a 95% confidence level. A total of 115 store-and-forward images (SAFI) were randomly selected and compared with hard-copy images (HCI) for technical quality. There was a significant difference in the quality of images. The results show that SAFI are far superior to HCI, traditionally used by clinicians for making primary diagnosis and that the superior quality of the SAFI improved diagnostic accuracy. This pilot study showed a high degree of confidence in videoconferencing for training GPs to carry out ultrasound clinics, enhancing their ability to make accurate diagnoses, and providing them with immediate access the second and higher opinion.

Education, Medical, Continuing↗
PubMed1998

Estimates of the severity of illnesses associated with bathing in marine recreational waters contaminated with domestic sewage.

BACKGROUND: During the summers of 1989-1992 we conducted four randomized intervention trials at four separate UK bathing locations judged of acceptable quality under current USEPA and EU criteria. The results showed bathers to be at increased risk of gastroenteritis, acute febrile respiratory illness (ICD-9 461-466, 480), ear and eye infections relative to non-bathers. The public health significance of these findings has been questioned based upon the unproven assumption that these illnesses are minor in nature and thus of questionable public health significance. METHODS: The severity of these illnesses or ailments in terms of duration of illness, percentage of participants seeking medical treatment, and number of days of lost normal daily activity among study participants reporting specific illnesses or ailments were assessed. In addition the attributable proportion of illness among the exposed (bathers) was calculated for each illness or ailment. RESULTS: Average duration of illness ranged from approximately 4 days to approximately 8 days depending on the specific illness reported. The percentage of study participants seeking medical treatment ranged from 4.2% to 22.2% while the percentage reporting the loss of at least one day of normal daily activity ranged from 7.0% to 25.9% depending on the illness reported. The overall percentage of each illness that can be directly attributable to exposure to marine waters contaminated with domestic sewage ranged from a low of 34.5% for gastroenteritis to a high of 65.8% for ear infections. CONCLUSIONS: To our knowledge, this is the first study to assess and report the severity of illnesses associated with bathing in recreational waters contaminated with domestic sewage. Illness associated with bathing in marine waters contaminated with domestic sewage can no longer be viewed as minor, and indeed can have a substantial impact on the public health.

Adult↗
PubMed1998

Effect of healed tympanic membrane perforations on umbo velocity in the rat.

Heterodyne laser interferometry was used to measure tympanic membrane (TM) velocity at the umbo during acoustic stimulation in 2 groups of rats. The control group had a normal TM, while in the other group the TM was perforated and then allowed to heal for at least 28 days. Umbo velocity functions for constant sound pressure level stimuli were obtained for test tones between 0.3 and 40.0 kHz in each animal. The results revealed that velocity was the same in the control and healed TMs below 3.0 kHz. Above 5.0 kHz, the velocity response in the healed ear was between 3 and 12 dB smaller than in the control ears. Histologic evaluation of the healed perforation revealed a thick fibrous reaction between the epidermal and lamina propria layers. The results indicated that the added mass of the scar tissue changed the middle- and high-frequency TM responses.

Acoustic Stimulation↗