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Biomedical subjects

D Larkin

Publications and source records attributed to D Larkin.

9 recordsLinked to original sources
PubMed2001

MPer1 and mper2 are essential for normal resetting of the circadian clock.

Mammalian Per1 and Per2 genes are involved in the mechanism of the circadian clock and are inducible by light. A light pulse can evoke a change in the onset of wheel-running activity in mice by shifting the onset of activity to earlier times (phase advance) or later times (phase delays) thereby advancing or delaying the clock (clock resetting). To assess the role of mouse Per (mPer) genes in circadian clock resetting, mice carrying mutant mPer1 or mPer2 genes were tested for responses to a light pulse at ZT 14 and ZT 22, respectively. The authors found that mPer1 mutants did not advance and mPer2 mutants did not delay the clock. They conclude that the mammalian Per genes are not only light-responsive components of the circadian oscillator but also are involved in resetting of the circadian clock.

Animals↗
PubMed2001

Using the Rasch measurement model to investigate the construct of motor ability in young children.

This paper reports the use of a Rasch measurement model, the Extended Logistic Model of Rasch (Andrich, 1988), to explore the construct of a general motor ability in young children. Data were collected from 332 five and six year old children performing 24 motor skills, including run, hop, balance and ball skills. The data were categorised based on threshold estimates provided by the measurement model. Gender differences in performances on items were hypothesised to contribute to initial item and person misfit for the total sample. The data for boys and for girls were separated and independently analysed resulting in improved item and person fit. Two different, unidimensional scales for boys and for girls were created.

Aptitude↗
PubMed1999

Creating performance categories from continuous motor skill data using a Rasch measurement model.

This paper reports the use of the Extended Logistic Model (ELM) of Rasch (Andrich, 1988), based on Item Response Theory, to validate the reduction of continuous motor skill data to categories of performance. The data were gathered from the performances of 5 and 6 year old children on 24 fundamental movement skills and involved different measurement units such as seconds, centimetres, scores and counts. In order to compare results across all skills the data were collapsed into discrete sets of categories. Several alternative cut-off locations based on normative data were considered. A feature of the ELM is that it can account for correct scoring of the response categories, but only if the threshold estimates derived from the data by the measurement model are correctly ordered in a hierarchical fashion, from lowest to highest. Should this be the case, a valid scoring function has been established. In this study, the data were successfully reduced to three categories based on the 15th and 85th percentile allowing further analysis to proceed.

Child↗
PubMed1993

Stability and change in children's skill.

This paper explores age-related performance variability, both within trials and between sessions, in repetitive hopping. The mean, the standard deviation (SD), and the coefficient of variation (CV) of several timing and ground-reaction-force variables of hopping were analysed by repeated-measures ANOVA for age-related effects across test sessions and foot used. Forty-five subjects in five age groups (3-4 years, 4-5 years, 6-7 years, 8-9 years, or Adult) performed self-paced, one-footed hopping on three occasions within one week. As was expected, the results showed main effects for Age in all force and time variables, with the exception of CV of medio-lateral force. No significant main effects for Feet were revealed. However, significant Feet x Session interactions were found in flight-time measures, with higher flight-time SD and lower CV for the non-preferred foot in Session 1, a reversal in Session 2, and a negligible difference in Session 3. Across sessions, decreased SD and CV for both vertical and medio-lateral force and shorter flight time indicated more efficient hopping. Overall, it was concluded that SD and CV measures were more sensitive measures of children's performance across repeated sessions than were mean scores and that the order of testing the limbs is an important consideration in experimental protocols when lateralized tasks are measured.

Adolescent↗
PubMed1991

Kinaesthetic abilities of clumsy children.

Kinaesthesis was examined in 80 clumsy and 80 control children aged between six and nine years. Seven tasks were administered which required passive and active movements in both kinaesthetic and kinaesthetic-visual modes. Clumsy children performed inferiorly on three tasks which involved passive or active demands. A range of tasks appears to be necessary to identify kinaesthetic dysfunction.

Child↗
PubMed1989

Movement laterality and its relationship to hemispheric specialization.

Hypothesized relationships between asymmetric brain processes and movement-related asymmetries are reviewed. Theories that attribute asymmetric preference and performance to hemisphere dominance have been superseded by more complex ideas: motor-specific and more global hemispheric specializations are considered to influence movement organization. Environmentally conditioned preferences and their relationship to preferential asymmetric movements are also addressed. The literature suggests that laterality may be dynamic, because task requirements have been shown to override asymmetric brain influences. This observation of the nature of laterality may result in a more flexible approach to the reeducation of preference and performance in brain-injured patients.

Brain↗
PubMedDate not supplied

Audit of cost and clinical outcome of cataract surgery.

An audit of routine cataract surgery in our hospital was carried out by examining records of 340 adult patients who underwent such surgery during October 1990. The category of intended accommodation (day case or inpatient), operative details, post-operative course and management were recorded, along with the outcome measures of visual acuity (unaided and corrected) and refractive error (spherical equivalent and cylinder). The costs of treatment, including post-operative management, were calculated for each patient. The results indicate that day case surgery under local anaesthesia was the most cost-effective method of cataract surgery, with no detrimental effect on clinical outcome.

Ambulatory Surgical Procedures↗