Laser absorption phenomena in flowing gas devices

A theoretical and experimental investigation is presented of inverse Bremsstrahlung absorption of CW CO2 laser radiation in flowing gases seeded with alkali metals. In order to motivate this development, some simple models are described of several space missions which could use laser powered rocket vehicles. Design considerations are given for a test call to be used with a welding laser, using a diamond window for admission of laser radiation at power levels in excess of 10 kW. A detailed analysis of absorption conditions in the test cell is included. The experimental apparatus and test setup are described and the results of experiments presented. Injection of alkali seedant and steady state absorption of the laser radiation were successfully demonstrated, but problems with the durability of the diamond windows at higher powers prevented operation of the test cell as an effective laser powered thruster

Lyrical Music Improves 5 km Time Trial Performance Compared to Non-Lyrical Music

This study examined the effects of lyrical music compared to non-lyrical music on 5 km running performance. Thirteen subjects with an average age of 33.5 ± 8.3 years of age ran three separate 5 km time trials. The first trial acted as a familiarization trial where no music was present, followed by either a lyrical or non-lyrical music trial in a random counterbalanced order. Trial times, RPE, HR, and questionnaire information was analyzed using paired samples t-tests, ANOVA, and multivariate regression analyses. Lyrical music showed a significant improvement over non-lyrical music improving performance time compared to non-lyrical music, on average by 36 ± 41s (p=.000). While not statistically significant, a trend showing lyrical music was faster than no music, followed by the slowest trial of non-lyrical music. No change was detected in HR, or RPE at the 3.05 km mark suggesting that at the end although subjects were working harder (indicated by the faster completion times) they do not perceive themselves to be working harder. A correlation between increased mileage and the decreased effects of music as an ergogenic aid was seen (p=.044 r=.638) which supports previous research. This study suggests that lyrical music may improve 5 km running performance compared to no lyrical music

Receptor protein tyrosine phosphatases control Purkinje neuron firing

Spinocerebellar ataxias (SCA) are a genetically heterogeneous family of cerebellar neurodegenerative diseases characterized by abnormal firing of Purkinje neurons and degeneration. We recently demonstrated the slowed firing rates seen in several SCAs share a common etiology of hyper-activation of the Src family of non-receptor tyrosine kinases (SFKs). However, the lack of clinically available neuroactive SFK inhibitors lead us to investigate alternative mechanisms to modulate SFK activity. Previous studies demonstrate that SFK activity can be enhanced by the removal of inhibitory phospho-marks by receptor-protein-tyrosine phosphatases (RPTPs). In this Extra View we show that MTSS1 inhibits SFK activity through the binding and inhibition of a subset of the RPTP family members, and lowering RPTP activity in cerebellar slices with peptide inhibitors increases the suppressed Purkinje neuron basal firing rates seen in two different SCA models. Together these results identify RPTPs as novel effectors of Purkinje neuron basal firing, extending the MTSS1/SFK regulatory circuit we previously described and expanding the therapeutic targets for SCA patients

Downhill running impairs activation and strength of the elbow flexors

PURPOSE: The aim of this study was to determine if knee extensor injury induced by 1 h of downhill running attenuated force production in uninjured skeletal muscle (e.g., elbow flexors). METHODS: Recreationally active subjects (n = 12) completed a two group (injury vs control) repeated measures design with the injury group running downhill for 1 h and the control group performing only the measurement procedures. Strength and percent voluntary muscle activation were measured using an isokinetic dynamometer and electrical stimulation of the elbow flexors and knee extensors before and after a fatigue protocol at the following time points in relation to the downhill run: 15 min pre, 15 min post, 24 h post, and 48 h post. Blood samples were collected at the same time points to measure IL-1β and TNF-α concentrations. RESULTS: Knee extensor strength was significantly reduced by 53.5±9.9% immediately post-injury and remained reduced for up to 48 h in the injury group. Elbow flexor strength was significantly reduced immediately and 24 h post-injury by 13.2±3.9% and 17.3±4.0% respectively in the injury group. Elbow flexor electrically stimulated strength was not found to be different at any time point (P = 0.561). Elbow flexor activation was significantly reduced compared to control at 24 and 48 h post-injury by 22.9±9.1% and 13.5±5.7% respectively. No differences were observed in IL-1β or TNF-α between groups. CONCLUSION: A 1 h downhill run significantly injured the knee extensors. The elbow flexor muscles remained uninjured based on electrically stimulated strength, but voluntary strength of these muscles was impaired due to reduced activation. This suggests an injury to the knee extensors can impair strength in uninjured muscles by reducing voluntary activation. The mechanism behind this reduction remains undetermined. INDEX WORDS: Downhill running, Muscle injury, Central nervous system, Inflammatio

Effects of PTSD and MDD Comorbidity on Psychological Changes during Surf Therapy Sessions for Active Duty Service Members

Together, posttraumatic stress disorder (PTSD) and major depressive disorder (MDD) are debilitating and commonly comorbid; however, the effects of this comorbidity on psychological outcomes during exercise programs, such as surf therapy, have not been examined. This study compared changes in depression/anxiety and positive affect during surf therapy sessions between active duty service members with comorbid PTSD and MDD and those with either disorder alone. The study applied DSM-5 criteria to baseline self-report measures to assign probable disorder status, and used a longitudinal design involving repeated measurements to assess outcomes within 6 weekly sessions. Service members completed validated self-report questionnaires using the Patient Health Questionnaire-4 and the Positive Affect Schedule before and after each session. Within surf therapy sessions, both the comorbid and single disorder groups reported significant improvements in symptoms of depression/anxiety and positive affect. However, those with comorbid PTSD and MDD experienced significantly greater reductions in depression/anxiety (beta = -1.22, p = .028) and significantly greater improvements in positive affect (beta = 3.94, p = .046) compared with the single disorder group. Surf therapy appears to have global effects on psychological symptom reduction and may be a useful adjunctive intervention for the treatment of comorbid PTSD and MDD in both clinical and community health settings

Effects of PTSD and MDD Comorbidity on Psychological Changes during Surf Therapy Sessions for Active Duty Service Members

Together, posttraumatic stress disorder (PTSD) and major depressive disorder (MDD) are debilitating and commonly comorbid; however, the effects of this comorbidity on psychological outcomes during exercise programs, such as surf therapy, have not been examined. This study compared changes in depression/anxiety and positive affect during surf therapy sessions between active duty service members with comorbid PTSD and MDD and those with either disorder alone. The study applied DSM-5 criteria to baseline self-report measures to assign probable disorder status, and used a longitudinal design involving repeated measurements to assess outcomes within 6 weekly sessions. Service members completed validated self-report questionnaires using the Patient Health Questionnaire-4 and the Positive Affect Schedule before and after each session. Within surf therapy sessions, both the comorbid and single disorder groups reported significant improvements in symptoms of depression/anxiety and positive affect. However, those with comorbid PTSD and MDD experienced significantly greater reductions in depression/anxiety (beta = -1.22, p = .028) and significantly greater improvements in positive affect (beta = 3.94, p = .046) compared with the single disorder group. Surf therapy appears to have global effects on psychological symptom reduction and may be a useful adjunctive intervention for the treatment of comorbid PTSD and MDD in both clinical and community health settings

Time-resolved temperature measurements during pulsed laser irradiation uslng thin film metal thermometers

In this article, we describe a technique using Nisi and Pt thin film metal thermometers to provide accurate temperature information on a nanosecond time scale during pulsed laser processing of materials. A surface layer of interest is deposited onto the thermometer layer, and temperatures are determined from temperature dependent changes in the metal film's resistance. Details concerning the design and fabrication of the device structure and experimental considerations in making nanosecond resolved resistance measurements are discussed. Simple analytical estimates are presented to extract quantities such as incident laser energy stored in the sample. Finally, transient temperature data in the thermometer film, in combination with heat flow calculations, allow temperature determination as a function of time and depth into the sample and, additionally, can provide information about material properties of the surface layer

The effects of an experimental programme to support students’ autonomy on the overt behaviours of physical education teachers

Although the benefits of autonomy supportive behaviours are now well established in the literature, very few studies have attempted to train teachers to offer a greater autonomy support to their students. In fact, none of these studies has been carried out in physical education (PE). The purpose of this study is to test the effects of an autonomy-supportive training on overt behaviours of teaching among PE teachers. The experimental group included two PE teachers who were first educated on the benefits of an autonomy supportive style and then followed an individualised guidance programme during the 8 lessons of a teaching cycle. Their behaviours were observed and rated along 3 categories (i.e., autonomy supportive, neutral and controlling) and were subsequently compared to those of three teachers who formed the control condition. The results showed that teachers in the experimental group used more autonomy supportive and neutral behaviours than those in the control group, but no difference emerged in relation to controlling behaviours. We discuss the implications for schools of our findings