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.     

Neuroimaging in children, adolescents and young adults with psychological trauma

Childhood psychological trauma is a strong predictor of psychopathology. Preclinical research points to the influence of this type of trauma on brain development. However, the effects of psychological trauma on the developing human brain are less known and a challenging question is whether the effects can be reversed or even prevented. The aim of this review is to give an overview of neuroimaging studies in traumatized juveniles and young adults up till 2012. Neuroimaging studies in children and adolescents with traumatic experiences were found to be scarce. Most studies were performed by a small number of research groups in the United States and examined structural abnormalities. The reduction in hippocampal volume reported in adults with PTSD could not be confirmed in juveniles. The most consistent finding in children and adolescents, who experienced psychological trauma are structural abnormalities of the corpus callosum. We could not identify any studies investigating treatment effects. Neuroimaging studies in traumatized children and adolescents clearly lag behind studies in traumatized adults as well as studies on ADHD and autism.     

Assessing the use of the Family Affluence Scale (FAS) among Irish schoolchildren

The objective of this analysis was to examine the answering rates, internal reliability and external validity of the Family Affluence Scale (FAS) employing data from the 2002 Irish Health Behaviour in School-aged Children study HBSC; a cross-sectional survey of 8,424 Irish schoolchildren aged 10-18. Father's occupation was reported by 80.6% of the schoolchildren and 60.6% reported on mother's occupation, while over 96% reported on the FAS items. Lower answering rates on parental occupation were found among younger schoolchildren and among those with poorer material circumstances. Analysis of the FAS revealed a moderate internal reliability and FAS scores were significantly associated with reported parental occupation. The traditional SES measures suffer from poor answering rates that pose a serious methodological threat. The FAS has moderate internal reliability and does not capture the SES status in full, but it has high completion rates, and can be used as an additional measure of SES in late childhood and adolescence.     

Cognitive defusion versus experiential avoidance in the reduction of smoking behaviour: an experimental and preliminary investigation

Background: Brief procedures that reduce smoking behaviour may be useful in reaching the many people that do not seek help for smoking addiction.

Objectives: The current study aimed to determine if one component of Acceptance and Commitment Therapy (ACT), cognitive defusion, could be useful in reducing smoking behaviour in a sample of students.

Methods: The study employed a between-subjects three-arm design. For one week, participants were asked to reduce their cigarette consumption. To aid them in their reduction, participants were randomly allocated to one of three conditions: the first received a defusion procedure, the second received an experiential avoidance procedure and a control condition received no procedure. For a second week, the instruction to reduce cigarette consumption was lifted. During both weeks participants were required to monitor their smoking behaviour via a tally diary system.

Results: The defusion condition smoked significantly less than the control condition during week one and significantly less than the control and experiential avoidance conditions during week two.

Conclusion: Results are discussed in terms of the potential utility of defusion in this domain, and the limitations of this preliminary research that would need to be addressed in future investigations.     

The contribution of inherited and acquired thrombophilic defects, alone or combined with antiphospholipid antibodies, to venous and arterial thromboembolism in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is associated with an increased risk of venous (VTE) and arterial thromboembolism (ATE). Lupus anticoagulant (LA) and anticardiolipin antibodies (ACAs) are established risk factors. We assessed the contribution of deficiencies of antithrombin, protein C, total protein S, factor V Leiden, the prothrombin G20210A mutation and APC resistance, either alone or in various combinations with LA and/or ACAs, to the thrombotic risk in a cohort of 144 consecutive patients with SLE. Median follow-up was 12.7 years. VTE had occurred in 10% and ATE in 11% of patients. LA,ACAs, factor V Leiden, and the prothrombin mutation were identified as risk factors for VTE. Annual incidences of VTE were 2.01 (0.74-4.37) in patients with one of these disorders and 3.05 (0.63-8.93) in patients with 2 disorders. The risk of VTE was 20- and 30-fold higher, respectively, compared with the normal population. In contrast with LA and ACAs, thrombophilic disorders did not influence the risk of ATE. In conclusion, factor V Leiden and the prothrombin mutation contribute to the risk of VTE in patients with SLE, and potentiate this risk when one of these thrombophilic defects are combined with LA and/or ACAs.     

Interaction of neuropeptide Y genotype and childhood emotional maltreatment on brain activity during emotional processing

Neuropeptide Y (NPY) has been associated with stress reactivity in affective disorders and is most densely expressed in the amygdala. An important stressor associated with affective disorders is the experience of childhood emotional maltreatment (CEM). We investigated whether the interaction of NPY risk genotype and CEM would affect brain activation. From the Netherlands Study of Depression and Anxiety, 33 healthy controls and 85 patients with affective disorders were scanned with functional magnetic resonance imaging while making gender decisions of emotional facial expressions. Results showed interactions between genotype and CEM, within carriers of the risk genotype, CEM was associated with higher amygdala activation, whereas CEM did not influence activation in non-risk carriers. In the posterior cingulate cortex (PCC), less activation was seen in those with CEM and the risk genotype, whereas genotype did not influence PCC activation in those without CEM. In addition, those carrying the risk genotype and with experience of CEM made a faster gender decision than those without CEM. Thus, the combined effect of carrying NPY risk genotype and a history of CEM affected amygdala and PCC reactivity, areas related to emotion, self-relevance processing and autobiographical memory. These results are consistent with the notion that the combination of risk genotype and CEM may cause hypervigilance.     

In vivo assessment of guided neural stem cell differentiation in growth factor immobilized chitosan-based hydrogel scaffolds

In this study, we demonstrate that a unique growth factor-biomaterial system can offer spatial control of growth factors with sustained signaling to guide the specific lineage commitment of neural stem/progenitor cells (NSPCs) in vivo. First, recombinant fusion proteins incorporating an N-terminal biotin tag and interferon-γ (IFN-γ), platelet derived growth factor-AA (PDGF-AA), or bone morphogenic protein-2 (BMP-2) were immobilized to a methacrylamide chitosan (MAC) based biopolymer via a streptavidin linker to specify NSPC differentiation into neurons, oligodendrocytes, or astrocytes, respectively. MAC was mixed with growth factors (immobilized or adsorbed), acrylated laminin, NSPCs, and crosslinked within chitosan conduits. This system mimics regenerative aspects of the central nervous system ECM, which is largely composed of a crosslinked polysaccharide matrix with cell-adhesive regions, and adds the new functionality of protein sequestration. We demonstrated that these growth factors are maintained at functionally significant levels for 28 d in vitro. In the main study, immobilized treatments were compared to absorbed and control treatments after 28 d in vivo (rat subcutaneous). Masson's Trichrome staining revealed that small collagen capsules formed around the chitosan conduits with an average acceptable thickness of 153.07 ± 6.02 μm for all groups. ED-1 staining showed mild macrophage clustering around the outside of chitosan conduits in all treatments with no macrophage invasion into hydrogel portions. Importantly, NSPC differentiation staining demonstrated that immobilized growth factors induced the majority of cells to differentiate into the desired cell types as compared with adsorbed growth factor treatments and controls by day 28. Interestingly, immobilized IFN-γ resulted in neural rosette-like arrangements and even structures resembling neural tubes, suggesting this treatment can lead to guided dedifferentiation and subsequent neurulation.     

Effects of essential oils from Cymbopogon citratus (DC) Stapf., Lippia sidoides Cham., and Ocimum gratissimum L. on growth and ultrastructure of Leishmania chagasi promastigotes

The current therapy for leishmaniasis, which affects annually about 2 million people, is far from satisfactory. All available drugs require parenteral administration and are potentially toxic. Plant essential oils have been traditionally used in folk medicine and appear as valuable alternative source for chemotherapeutic compounds. In this study, we demonstrated the effect of essential oils from Cymbopogon citratus, Lippia sidoides, and Ocimum gratissimum on growth and ultrastructure of Leishmania chagasi promastigote forms. Steam distillation was used to isolate the essential oils, and their constituents were characterized by gas chromatography coupled to mass spectrometry and nuclear magnetic resonance. All essential oils showed in vitro inhibitory action on L. chagasi promastigotes growth in a dose-dependent way, with IC₅₀/72 h of 45, 89, and 75 μg/mL for C. citratus, L. sidoides, and O. gratissimum, respectively. Drastic morphological alterations were observed in all essential oil-treated parasites, including cell swelling, accumulation of lipid droplets in the cytoplasm, and increase of acidocalcisome volume. Furthermore, aberrant-shaped cells with multi-septate body were observed by scanning electron microscopy, suggesting an additional effect on cytokinesis. Taken together, our data show that these essential oils affect the parasite viability being the C. citratus essential oil the most effective against L. chagasi.