The Effect of Court Location and Available Time on the Tactical Shot Selection of Elite Squash Players

No previous research in squash has considered the time between shots or the proximity of the ball to a wall, which are two important variables that influence shot outcomes. The aim of this paper was to analyse shot types to determine the extent to which they are played in different court areas and a more detailed analysis to determine whether the time available had an influence on the shot selected. Ten elite matches, contested by fifteen of the world’s top right handed squash players (age 27 ± 3.2, height 1.81 ± 0.06 m, weight 76.3 ± 3.7 kg), at the men’s World Team Championships were processed using the SAGIT/Squash tracking system with shot information manually added to the system. Results suggested that shot responses were dependent upon court location and the time between shots. When these factors were considered repeatable performance existed to the extent that one of two shots was typically played when there was limited time to play the shot (< 1.20s). For example, it was clear that when players did not have a lot of time to hit the ball (low time i.e. < 1.06s, and mid time i.e. 1.06 - 1.20s) in the front left corner close to the side wall, the crosscourt lob was used frequently (44.30% and 36.31% respectively) whereas when there was more time this shot was seldom used (13.64%). Consequently variant and invariant behaviour were shown to exist in elite squash although for the first time it was suggested that the availability of time to play a shot contributed to which of these behaviours was evident. This analysis could be extended by adopting a case study approach to see how individual differences in strategy and tactics affect shot selections.

Key points

• Previous research has suggested that a playing strategy, elements decided in advance of the match, may be evident for elite players by examining court location and preceding shot type, however these parameters alone are unlikely to be sufficient predictors.
• At present there is no known analysis in squash, or indeed in any of the racket sports, that has quantified the time available to respond to different shot types. An understanding of the time interval between shots and the movement characteristics of the player responding to different shots according to the court positions might facilitate a better understanding of the dynamics that determine shot selection.
• Some elements of a general playing strategy were evident e.g. predominately hitting to the back left of the court, but tactical differences in shot selection were also evident on the basis of court location and time available to play a shot.

Key words: Strategy, tactics, SAGIT, invariant behaviour.     

HIV sero-discordance among married HIV patients initiating anti-retroviral therapy in northern Vietnam

Background

In many countries in Asia, the HIV epidemic is in a concentrated phase, with high prevalence in certain risk groups, such as men who inject drugs. There is also a rapid increase of HIV among women. The latter might be due to high levels of sero-discordant couples and increasing transmission from male to female partners over time.

Methods

All adult married patients initiating antiretroviral treatment at four out-patient clinics in Quang Ninh province in north-eastern Vietnam between 2007 and 2009 were asked to participate in the study. Clinical information was extracted from patients’ records, and a structured questionnaire was used to collect social, demographic and economic data.

Results

Two hundred eighty-eight married patients for whom information on the HIV status of their spouse was available were included in the study. Overall, the sero-discordance rate was 58%. The sero-discordance rate was significantly higher among married males, 71% had spouses not infected, than married females, of whom 18% had spouses not infected. Other factors associated with a high rate of sero-discordance were injection drug use (IDU) history, tuberculosis (TB) history and the availability of voluntary counselling and testing (VCT) in residential locations. High sero-concordance was associated with college/university education.

Conclusion

The sero-discordance was significantly higher among married males than married females. Other factors also related to high sero-discordance were history of IDU, history of TB and the availability of VCT in residential locations. In contrast, college/university education and female sex were significantly related to low sero-discordance. To contain the increasing HIV prevalence among women, measures should be taken to prevent transmission among sero-discordant couples. Trial registration NCT01433601

     

The impact of head and neck radiation on airway management: a retrospective data review

Canadian Journal of Anesthesia/Journal canadien d'anesthésie -     

Development of a portable electrochemical loop mediated isothermal amplification (LAMP) device for detection of hepatitis B virus

The objective of this study was to develop a simple, inexpensive prototype device for rapid detection of hepatitis B virus (HBV). The device was able to simultaneously amplify, detect and quantify the target HBV DNA. The system was fabricated from a custom-made electrochemical set-up of which the temperature was thermostatically controlled by a water bath. Real-time monitoring of HBV DNA was accomplished by measuring the response of redox indicator in the reaction mixture. Concentration of HBV DNA in the samples was determined from the peak high ratio (PHR) and threshold time relationship. The signal was processed by sigmoidal model fitting to enhance the accuracy of the results. Key parameters including concentrations of redox indicator and reaction temperatures were optimized. Sensitivity and specificity of the method toward HBV DNA were evaluated. The prototype was capable of real-time amplification and detection of HBV DNA with concentration as low as 6.18 fg μl⁻¹. The test showed high specificity against HBV DNA. The system was also able to detect HBV positive serum directly with simple thermal pretreatment instead of tedious DNA extraction. The electrochemical set-up was compatible with microfluidic platforms and can be readily adapted for efficient and high throughput point-of-care (POC) diagnosis of HBV.

A novel prototype device using LAMP and electrochemical drop cell set-up for rapid detection of hepatitis B virus.     

Changing Blue Fluorescent Protein to Green Fluorescent Protein Using Chemical RNA Editing as a Novel Strategy in Genetic Restoration

Using the transition from cytosine of BFP (blue fluorescent protein) gene to uridine of GFP (green fluorescent protein) gene at position 199 as a model, we successfully controlled photochemical RNA editing to effect site‐directed deamination of cytidine (C) to uridine (U). Oligodeoxynucleotides (ODNs) containing 5′‐carboxyvinyl‐2′‐deoxyuridine (^CVU) were used for reversible photoligation, and single‐stranded 100‐nt BFP DNA and in vitro‐transcribed full‐length BFP mRNA were the targets. Photo‐cross‐linking with the responsive ODNs was performed using UV (366 nm) irradiation, which was followed by heat treatment, and the cross‐linked nucleotide was cleaved through photosplitting (UV, 312 nm). The products were analyzed using restriction fragment length polymorphism (RFLP) and fluorescence measurements. Western blotting and fluorescence‐analysis results revealed that in vitro‐translated proteins were synthesized from mRNAs after site‐directed RNA editing. We detected substantial amounts of the target‐base‐substituted fragment using RFLP and observed highly reproducible spectra of the transition‐GFP signal using fluorescence spectroscopy, which indicated protein stability. ODNc restored approximately 10% of the C‐to‐U transition. Thus, we successfully used non‐enzymatic site‐directed deamination for genetic restoration in vitro. In the near future, in vivo studies that include cultured cells and model animals will be conducted to treat genetic disorders.