Search PubMed⌕ Search

Biomedical subjects

S W Brown

Publications and source records attributed to S W Brown.

At least 19 recordsLinked to original sources
PubMed2002

The role of practice and automaticity in temporal and nontemporal dual-task performance.

Research on time and attention shows that a nontemporal task may interfere with a concurrent timing task by making time judgments shorter, more variable, and/or more inaccurate compared to timing-only conditions. Brown (1998, Psychological Research, 61, 71-81) counteracted the interference effect by giving subjects automaticity training on a nontemporal task to reduce the amount of processing resources the task required. Such practice attenuated interference in timing. Two new experiments were designed to replicate and extend the previous findings. Subjects generated a series of 5-s temporal productions under single-task (timing only) and dual-task (timing plus nontemporal task) conditions. The nontemporal tasks were pursuit rotor tracking (Experiment 1), and mirror-reversed reading (Experiment 2). We employed a pretest-practice-posttest paradigm, with the practice sessions devoted to performance of the nontemporal task. Pretest-posttest comparisons showed that practice reduced interference in timing in both experiments. Dual-task probe trials were given during the practice sessions to trace the time course of the improvement in timing. The results showed that interference in timing was reduced with even small amounts of practice. The findings support the idea that timing is very sensitive to changes in the allocation of attentional resources.

Adolescent↗
PubMed2001

Electron and nuclear spin interactions in the optical spectra of single GaAs quantum dots.

Fine and hyperfine splittings arising from electron, hole, and nuclear spin interactions in the magneto-optical spectra of individual localized excitons are studied. We explain the magnetic field dependence of the energy splitting through competition between Zeeman, exchange, and hyperfine interactions. An unexpectedly small hyperfine contribution to the splitting close to zero applied field is described well by the interplay between fluctuations of the hyperfine field experienced by the nuclear spin and nuclear dipole/dipole interactions.

Journal Article↗
PubMed2001

The use of seizure-alert dogs.

We report our experience of training dogs to assist people with epilepsy by providing a useful warning of seizures. An unexpected finding has been that human subjects report an improvement in seizure rate. This may be related to increased confidence and activity levels. We have observed some hazards associated with untrained dogs, which raises questions about future experimental design. We plan further research to test our method and assess outcomes more formally. Recent changes in UK quarantine law provide an opportunity for further international collaboration.

Animals↗
PubMed2000

Expressed emotion in the families of young people with epilepsy.

The parents of 41 young people with epilepsy who were living in the same household as the patients were interviewed using the Camberwell Family Interview, and ratings of expressed emotion (EE) carried out according to standard criteria. The presence of any seizures in the 6 months prior to interview was found to be a predictor of EE (p= 0. 0017). Absolute seizure frequency, as well as presence or absence of seizures was also found to vary with the EE score. Fathers may exhibit high EE by critical comments, mothers by emotional over involvement. Although it is unclear whether high EE is the result of seizures, or whether high EE makes seizures more likely to occur, an intervention study aimed at assessing the effect of lowering parental EE levels on young people's seizure frequency might be worth pursuing.

Adolescent↗
PubMed2000

Should people with epilepsy have untrained dogs as pets?

We report 36 cases of pet dogs, who suffered significant adverse health effects as a result of spontaneously reacting to, or anticipating, epileptic seizures in their human owners. These included three cases in which the dog died, and 12 cases in which the dog exhibited aggressive behaviour towards humans. However, where dogs have been specially trained as Seizure Alert Dogs, these adverse effects have not been seen. As interest grows in the use of dogs to anticipate human seizures and support people with epilepsy, it is important to emphasize the need for specially chosen dogs to be used, and for them to be specially trained. This also raises concerns about potential use of untrained dogs as controls in future research using Seizure Alert Dogs.

Adult↗
PubMed1999

Seizure-alert dogs--fact or fiction?

Anecdotal evidence suggests that some dogs may be able to sense the onset of seizures and other medical conditions in humans, although this has never been explored scientifically. There is, however, evidence that dogs can be specially trained to recognize specific changes preceding a seizure and give an overt signal enabling the dog to warn his/her owner. The introduction of the use of dogs to detect and accurately predict the onset of a seizure, giving sufficient time for a person to take control of the situation will have a dramatic impact on quality of life. Support Dogs, a registered charity which trains dogs to assist disabled people, has successfully trained several 'Seizure-alert dogs'. As training progressed, the dogs were able to provide overt signals to their owners within time periods varying from 15 to 45 minutes prior to a seizure occurring. Each dog had an accurate prediction time and, in each case, the owner's seizure frequency was reduced.

Adolescent↗
PubMed1999

A comparative morphological study of human germ cells in vitro or in situ within seminiferous tubules.

For many infertile couples, intracytoplasmic germ cell/spermatozoon injection into unfertilized eggs may be their only hope for producing their own biological children. Thus far, success with injection of pre-spermatozoan germ cells such as round spermatids has not been as great as that of spermatozoon injection. This could be due in part to the difficulty of identifying younger (less mature) male germ cells in testicular biopsy dispersions. To improve the identification of various types of live, dispersed, human testicular cells in vitro, a comparative study of the morphological characteristics of human spermatogenic germ cells in vitro or in situ within seminiferous tubules was conducted. Live human testicular tissue was obtained from an organ-donating, brain-dead person with a high density of various germ cells. A cell suspension was obtained by enzymatic digestion, and cells were cultured for 3 days in an excessive volume (100-fold medium:cells; v:v) of HEPES-TC 199 medium at 5 degrees C and observed live with Nomarski optics (interference-contrast microscopy). For comparative purposes, testes from ten men obtained at autopsy were fixed, embedded in epoxy resin, sectioned at 20 microm, and observed unstained by Nomarski optics. This approach allowed comparison of morphological characteristics of individual germ cells seen in vitro or in situ in the human testis. In both live and fixed preparations from control men with varied daily sperm production rates, Sertoli cells have oval to pear-shaped nuclei with indented nuclear envelopes and large nucleoli, which makes their appearance distinctly different from germ cells. The size, shape, and chromatin pattern of nuclei, and the presence of meiotic metaphase figures, acrosomic vesicles/structures, tails, and/or mitochondria in the middle piece of germ cells are characteristically seen in live cells in vitro and in those cells observed in the fixed seminiferous tubules. Hence, this comparative approach allows verification of the identity of individual germ cells seen in vitro and provides a checklist of distinguishing characteristics of live human germ cells, to be used by scientists and technical staff in infertility clinics when selecting specific germ cells from a testicular aspirate or enzymatically digested biopsy.

Adult↗
PubMed1998

Optical NMR from single quantum dots.

Nuclear magnetic resonance (NMR) from constituent Ga and As nuclei was optically detected on excitonic recombination in single GaAs quantum dots formed by interface fluctuations in GaAs/Al0.3Ga0.7As quantum wells. Orientation of the nuclear spin system by optical pumping causes an Overhauser shift of the excitonic energy levels proportional to the degree of nuclear orientation. NMR was subsequently detected by monitoring changes in the combined Overhauser plus Zeeman splitting of excitons localized in single quantum dots as the RF frequency was swept through a nuclear resonance. The NMR signals originate from approximately 10(5) nuclei in the quantum dot-with dimensions of approximately 4 nm X 10 nm X 100 nm--illustrating the extreme sensitivity and spatial resolution of the technique. NMR from such small structures provides a chemically specific probe of the local environment on the nanometer scale.

Arsenicals↗
PubMed1998

Interpersonal forgiving in close relationships: II. Theoretical elaboration and measurement.

Interpersonal forgiving was conceptualized in the context of a 2-factor motivational system that governs people's responses to interpersonal offenses. Four studies were conducted to examine the extent to which forgiving could be predicted with relationship-level variables such as satisfaction, commitment, and closeness; offense-level variables such as apology and impact of the offense; and social-cognitive variables such as offender-focused empathy and rumination about the offense. Also described is the development of the transgression-related interpersonal motivations inventory--a self-report measure designed to assess the 2-component motivational system (Avoidance and Revenge) posited to underlie forgiving. The measure demonstrated a variety of desirable psychometric properties, commending its use for future research. As predicted, empathy, apology, rumination, and several indexes of relationship closeness were associated with self-reported forgiving.

Adult↗
PubMed1998

Influence of individual differences in temporal sensitivity on timing performance.

This research was designed to examine the consistency of individual differences in timing. Subjects were tested initially on a temporal-signal-detection task. In a series of trials, subjects judged whether a stimulus figure was displayed for either 12 s or greater than 12 s. Task performance was used to classify the subjects into groups with high or low temporal sensitivity (d'). Later, the subjects were tested on two classic time-judgment tasks. In a temporal-interference task, subjects reproduced intervals of 8-16 s during which they had rehearsed 0, 3, or 7 digits. Absolute error in time judgments increased linearly as a function of task demands. However, subjects with low temporal sensitivity made more error under all conditions compared with those with high sensitivity. In an isochronous-tapping task, subjects produced a series of 2-s and 5-s intervals. The low-temporal-sensitivity group produced more variable and inaccurate responses than the high-sensitivity group. The results demonstrate cross-situational consistency in timing performance across different tasks, time-judgment methods, and stimulus durations.

Adult↗
PubMed1998

Cavitation phenomena in water involving the reflection of ultrasound pulses from a free surface, or from flexible membranes.

We report findings from studies of water subjected to tension by pulsed dynamic stressing which may have significance in the context of assessing the safety of biomedical applications of low-frequency ultrasound. When incident on bubbles near a free surface (or a flexible membrane), shockwaves generated by cavitation bubble collapse are found to lead to the production of liquid jets which are directed towards the surface. Tension pulses generated by reflection of these shockwaves at a free surface initiate, and propagate, the growth of further cavitation bubbles. Estimates of the tensile strength of water, Fc, from measurements of the velocity of these pulses suggest that Fc is far higher than has previously been reported for experiments involving the reflection of low-frequency ultrasound; and the estimate of Fc reported here considerably exceeds the values of tension thought to be generated by ultrasound in many biomedical applications.

Photography↗
PubMed1998

Process-oriented critical pathways in inpatient psychiatry: our first year.

The critical pathway methodology of assigning and timing staff interventions and expected patient outcomes has developed worldwide recognition, but is less likely to be used in psychiatry than in other medical fields. At St. Mary's in Rochester, New York, an interdisciplinary team adapted the critical pathway concept to meet the needs of an acute inpatient population with relative success. Although staff education needs continue and plans to modify the pathway are in progress, all staff feel that the critical pathway is a viable tool for enhancing patient care and optimizing resources use. Benefits, obstacles, and suggestions are discussed.

Critical Pathways↗
PubMed1998

Epilepsy--a guide to medical treatment. 1: Antiepileptic drugs.

The epilepsies are the commonest of serious disorders of brain function. Medical, psychological, social and financial implications can adversely affect quality of life in both patient and family. Accurate categorization of seizure type and epilepsy syndrome, with appropriate choice of drug and other management, can minimize the burden of a seizure disorder.

Adult↗
PubMed1998

Epilepsy--a guide to medical treatment. 2: Non-drug aspects.

Approximately 30-40% of people with epilepsy continue to have seizures despite drug treatment. Factors related to cognitive abilities, physical handicap, psychiatric illness and social circumstances are of great importance in the overall management.

Adolescent↗
PubMed1997

[Experiences in Great Britain with add-on therapy of epilepsy].

The new antiepileptic drugs represent a major part of the wider range of opportunities now available to treat epilepsy. Because of the way in which drugs are developed and the way in which product licences are granted, data sheet information does not necessarily reflect the optimum range of indications, dose escalation, maximum dose or degree of adverse events. Experience suggests that in most cases better results are obtained with slower dose escalations, and that often higher doses may be usefully achieved than those recommended in data sheets. All the new drugs are probably effective in monotherapy.

Anticonvulsants↗
PubMed1997

Paediatric one lung ventilation in the prone position.

Pulmonary lobectomy in the presence of infected secretions requires isolation of the affected lung to prevent soiling of the healthy lung. In young children this is usually accomplished using a Fogarty embolectomy catheter. We report the successful combination of a Fogarty catheter, a tracheal tube and the prone position, which provided adequate ventilation and oxygenation as well as excellent surgical exposure.

Bronchiectasis↗