Visualizing the uncertainty in the relationship between seasonal average climate and malaria risk.

Around $1.6 billion per year is spent financing anti-malaria initiatives, and though malaria morbidity is falling, the impact of annual epidemics remains significant. Whilst malaria risk may increase with climate change, projections are highly uncertain and to sidestep this intractable uncertainty, adaptation efforts should improve societal ability to anticipate and mitigate individual events. Anticipation of climate-related events is made possible by seasonal climate forecasting, from which warnings of anomalous seasonal average temperature and rainfall, months in advance are possible. Seasonal climate hindcasts have been used to drive climate-based models for malaria, showing significant skill for observed malaria incidence. However, the relationship between seasonal average climate and malaria risk remains unquantified. Here we explore this relationship, using a dynamic weather-driven malaria model. We also quantify key uncertainty in the malaria model, by introducing variability in one of the first order uncertainties in model formulation. Results are visualized as location-specific impact surfaces: easily integrated with ensemble seasonal climate forecasts, and intuitively communicating quantified uncertainty. Methods are demonstrated for two epidemic regions, and are not limited to malaria modeling; the visualization method could be applied to any climate impact.

The effect of knee-flexion angle on wheelchair turning.

The increasingly popular hyperflexed knee-flexion angle was evaluated to determine its effects on wheelchair turning. Twenty able-bodied subjects were tested comparing the effect of full knee extension and full knee flexion on a number of parameters. We empirically measured the angular velocity of subjects spinning 720 degrees in place, subjects' perceived ease of wheelchair turning, the overall length of the wheelchair, the anteroposterior position of the center of mass (COM), rolling resistance, turning resistance and rear-wheel traction. The combined moment of inertia of the wheelchair and system was modeled. We found that, in comparison with full extension, fully flexing the knees increased angular velocity by 40% and was perceived to be 66% easier by subjects. Overall length decreased by 39%, COM moved rearward 38%, rolling and turning resistance decreased by 21% and 17% respectively, rear-wheel traction increased by 12% and moment of inertia decreased by 42%. All empirically tested parameters were statistically significant (p<0.007). We conclude that the knee-flexion angle has a significant effect on wheelchair turning. The implications of these findings for wheelchair design and prescription will need to be validated on actual wheelchair users and for smaller increments in knee-flexion range.

Proactive balance strategy while maintaining a stationary wheelie.

OBJECTIVE: To test the hypothesis that a reactive balance strategy is used while maintaining a stationary wheelie, specifically that a forward pitch from the wheelie equilibrium position is associated with a forward displacement of the wheelchair and a rear pitch with rear displacement, with the displacement slightly after the change in pitch. DESIGN: Descriptive and quantitative kinematic analysis. SETTING: Kinesiologic laboratory. PARTICIPANTS: A convenience sample of 10 able-bodied adults. INTERVENTION: Subjects taught to pop and maintain a stationary wheelie for 15 seconds while remaining within a .75 x .75 m2. Three trials of 5 seconds; digitized targets videotaped for analysis. MAIN OUTCOME MEASURES: Pitch angle and rear-wheel position of the wheelchair, derived from digitized videotape and time-series analysis of phase lag. RESULTS: There was an inverse relationship between the direction of pitch and linear displacement-rear pitch was associated with forward wheel displacement and forward pitch was associated with rearward wheel displacement. The mean pitch angle +/- standard deviation was 13.6 degrees +/- 2.3 degrees and the mean horizontal position of the wheelchair was 0.0 +/- 4.9cm. There was little or no phase lag between pitch and displacement. CONCLUSIONS: Wheelie performers maintaining a stationary wheelie appeared to use a proactive balance strategy, in which they used a functional base of support that was larger than the geometric one. These findings may have significance for those who are learning and teaching wheelies and provide broader insights into the nature of dynamic balance.

A unique insight into the incidence of rugby injuries using referee replacement reports.

OBJECTIVES: To obtain further information the incidence of injuries and playing positions affected in club rugby in Scotland. METHODS: Routine reports of injury (permanent) and blood (temporary) replacements occurring in competitive club rugby matches by referees to the Scottish Rugby Union during seasons 1990-1991 to 1996-1997 were analysed. RESULTS: A total of 3,513 injuries (87 per 100 scheduled matches) and 1,000 blood replacements (34 per 100 scheduled matches) were reported. Forwards accounted for 60% of the injury and 72% of the blood replacements. Flankers and the front row were the most commonly replaced forwards while wing and centre three quarters were the most vulnerable playing positions among backs. The incidence of injury replacements increased as the match progressed up until the last 10 minutes when the trend was reversed. Blood replacements showed a different pattern with 60% occurring during the first half of the match. CONCLUSION: The most important finding of the study was reliability of referees in documenting the vulnerability of certain playing positions, and the timing when injuries took place, thus assisting coaches and team selectors when choosing replacement players for competitive club and representative rugby matches. This study re-emphasises the need for continuing epidemiological research.

Locomotor-respiratory coupling during axillary crutch ambulation.

OBJECTIVE: To test the hypotheses that locomotor-respiratory coupling occurs in humans using axillary crutches in a swing-through ambulation pattern and that expiration occurs during crutch-stance phase during locomotor-respiratory coupling. DESIGN: Eighteen able-bodied persons were trained in one-footed swing-through gait with axillary crutches. Then, as subjects walked at "somewhat hard" speeds (Borg) on a motorized treadmill for 5 min, we recorded signals from a crutch pressure switch and a mouthpiece-mounted thermocouple. Coupling was defined as being present when the onset of inspiration varied by < or = 5% with respect to the onset of the crutch gait cycle for a minimum of 10 consecutive gait cycles and when there was no drift on a raster plot of the respiratory phases relative to the onset of the gait cycle. RESULTS: Ten (56%) of the 18 subjects exhibited locomotor-respiratory coupling on 1-4 occasions each, with episodes lasting 11.3-148 sec. In 17 (89%) of the 19 episodes of 1:1 locomotor-respiratory coupling, expiration occurred during the crutch-stance phase of the gait cycle and inspiration occurred during crutch swing. CONCLUSIONS: Transient 1:1 locomotor-respiratory coupling occurs in many able-bodied subjects ambulating with axillary crutches and a swing-through gait. Expiration is most often associated with the crutch-stance phase of the gait cycle. This study may have implications for training axillary crutch users.

Impact of professionalism on injuries in rugby union.

OBJECTIVES: To measure the frequency and nature of injuries occurring in competitive matches since professionalism was introduced in rugby union. METHODS: The cohort study previously conducted in players from senior rugby clubs in the Scottish Borders in 1993-1994 when rugby union was an entirely amateur sport was repeated in 1997-1998. The same injury definition, outcome criteria, and method of calculating playing hours were used. In total, 803 (84%) of 960 eligible players participated, including all 30 adult players who played professionally for the Scottish Rugby Union or Border Reivers District. The 576 injury episodes in 381 of these players in competitive matches were compared with the 373 injuries in 266 players out of 975 (94%) who were eligible and registered with the same senior rugby clubs in 1993-1994. Outcomes were the occurrence of injury episodes, days away from playing or training for rugby, and time lost to employment or attendance at school/college as a consequence of being injured. RESULTS: The proportion of players who were injured almost doubled from 1993-1994 to 1997-1998, despite an overall reduction of 7% of the playing strength of participating clubs. Period prevalence injury rates rose in all age specific groups, particularly in younger players. This translated into an injury episode every 3.4 matches in 1993-94, rising to one in every 2.0 matches in 1997-1998. An injury episode occurred in a professional team for every 59 minutes of competitive play. Professional players sustained a higher proportion of recurrent injuries, particularly in the early part of the season. Some 56% of all their days lost to the game were caused by injuries to the muscles, ligaments, and joints of the knee, hip, and thigh. CONCLUSIONS: The introduction of professionalism in rugby union has coincided with an increase in injuries to both professional and amateur players. To reduce this, attention should be focused on the tackle, where many injuries occur. The International Rugby Board should place a moratorium on the use of protective equipment in competitive matches until its contribution to player morbidity has been fully assessed.

Menstruation, the oral contraceptive pill, and acute appendicitis.

OBJECTIVE: To find out if there was any association between histologically confirmed acute appendicitis, menstruation, and the use of the oral contraceptive pill. DESIGN: Retrospective study. SETTING: District general hospital, Scotland. SUBJECTS: 366 consecutive patients (median age 21, range 10-51) with histologically confirmed acute appendicitis during the period 1981-1990 were studied, 314 of whom were having menstrual cycles. 208 patients with physiological menstrual cycle were included in the study, and 82 patients were taking the oral contraceptive pill. INTERVENTIONS: Prospectively collected standardised data using computer assisted diagnosis of acute abdominal pain was used to review patients with histologically confirmed acute appendicitis. RESULTS: Acute appendicitis was confirmed in 17/208 of patients (8%) who were menstruating, which is significantly less than might be expected (p < 0.003). 5/82 (6%) of those taking oral contraception had withdrawal bleeding and acute appendicitis (p = 0.2). CONCLUSIONS: Acute appendicitis is less common among women during physiological menstruation, but no differences are noted during the withdrawal bleeding phase when taking oral contraception.

The contribution of vision to wheelie balance.

OBJECTIVE: To test the hypothesis that vision plays an important role in the maintenance of balance during a stationary wheelchair maneuver in which the wheelchair user lifts and maintains the chair's front wheels off the floor (wheelie). DESIGN: Within-subject comparisons of the ability of subjects to perform wheelies with their eyes open (EO) and their eyes closed (EC). SETTING: Kinesiologic laboratory. PARTICIPANTS: Ten able-bodied adults, a sample of convenience. MAIN OUTCOME MEASURES: Postural sway, as reflected by the standard deviation of sagittal-plane movements of the center of pressure of the chair's right rear wheel on a force platform during a 10-second stationary wheelie balance, and the number of mistrials. RESULTS: The postural sway for all trials (3 EO and EC data collections at the end of each of 3 one-hour training sessions) was 88% greater with the EC than with the EO condition (p < .001) and the number of mistrials was 324% greater (p = .001). By the end of the final training session, the postural sway with the EC (4.0cm) was still 100% greater than with the EO (2.0cm) (p < .001) although there was no longer a difference in the number of mistrials. CONCLUSION: Vision plays an important role in the maintenance of a stationary wheelie, but wheelies can be maintained with the eyes closed. These findings are relevant to the training of wheelchair users and also provide broader insights into the nature of wheelchair function and dynamic balance.

Walker inlet-closure strap for unsteady patients with lower-extremity amputations.

Some patients with lower-extremity amputations who use a walker fall backwards after advancing too far forward into the walker's base of support. In a pilot study of 14 patients with unilateral lower-extremity amputations who stepped into the forward two thirds of the walker base, this problem was corrected by using a knee-high elastic strap to close the open posterior "inlet" of the walker. Without the strap, the stance-phase position of the leading ankle was in the forward third of the walker base for 8 subjects and in the middle third for 6. With the walker strap, the ankle position was in the middle third for one subject, in the posterior third for 6, and at or behind the walker inlet for 7 (p < .0002). This simple intervention appears to correct the potentially dangerous behavior of stepping too far into the walker base.

Cystic hygroma in an adult: a case report.

Cystic hygromas are benign lesions arising due to an abnormality in lymphatic development and only rarely present in adults. Adequate radiological imaging prior to surgery is important as incomplete excision often leads to recurrence. Several adjunctive therapies have been shown to be beneficial in recurrent or inaccessible lesions but these are not in common use. We describe the case of a cystic lymphangioma appearing in adulthood that presented a diagnostic and therapeutic challenge.

Factors influencing tackle injuries in rugby union football.

OBJECTIVES: To assess the influence of selected aspects of lifestyle, personality, and other player related factors on injuries in the tackle. To describe the detailed circumstances in which these tackles occurred. METHODS: A prospective case-control study was undertaken in which the tackling and tackled players ("the cases") involved in a tackle injury were each matched with "control" players who held the same respective playing positions in the opposing teams. A total of 964 rugby matches involving 71 senior clubs drawn from all districts of the Scottish Rugby Union (SRU) were observed by nominated linkmen who administered self report questionnaires to the players identified as cases and controls. Information on lifestyle habits, match preparation, training, and coaching experience was obtained. A validated battery of psychological tests assessed players' trait anger and responses to anger and hostility. The circumstances of the tackles in which injury occurred were recorded by experienced SRU coaching staff in interviews with involved players after the match. RESULTS: A total of 71 tackle injury episodes with correct matching of cases and controls were studied. The following player related factors did not contribute significantly to tackle injuries: alcohol consumption before the match, feeling "below par" through minor illness, the extent of match preparation, previous coaching, or practising tackling. Injured and non-injured players in the tackle did not differ in their disposition toward, or expression of, anger or hostility. Some 85% of tackling players who were injured were three quarters, and 52% of injuries occurred when the tackle came in behind the tackled player or within his peripheral vision. Either the tackling or tackled player was sprinting or running in all of these injury episodes. One third of injuries occurred in differential speed tackles--that is, when one player was travelling much faster than the other at impact. The player with the lower momentum was injured in 80% of these cases. Forceful or crunching tackles resulting in injury mostly occurred head on or within the tackled player's side vision. CONCLUSIONS: Attention should be focused on high speed tackles going in behind the tackled player's line of vision. Comparative information on the circumstances of the vast majority of tackles in which no injury occurs is required before any changes are considered to reduce injuries in the tackle.