Tomography of atomic number and density of materials using dual-energy imaging and the Alvarez and Macovski attenuation model

Dual-energy computed tomography and the Alvarez and Macovski [Phys. Med. Biol. 21, 733 (1976)] transmitted intensity (AMTI) model were used in this study to estimate the maps of density (ρ) and atomic number (Z) of mineralogical samples. In this method, the attenuation coefficients are represented [Alvarez and Macovski, Phys. Med. Biol. 21, 733 (1976)] in the form of the two most important interactions of X-rays with atoms that is, photoelectric absorption (PE) and Compton scattering (CS). This enables material discrimination as PE and CS are, respectively, dependent on the atomic number (Z) and density (ρ) of materials [Alvarez and Macovski, Phys. Med. Biol. 21, 733 (1976)]. Dual-energy imaging is able to identify sample materials even if the materials have similar attenuation coefficients at single-energy spectrum. We use the full model rather than applying one of several applied simplified forms [Alvarez and Macovski, Phys. Med. Biol. 21, 733 (1976); Siddiqui et al., SPE Annual Technical Conference and Exhibition (Society of Petroleum Engineers, 2004); Derzhi, U.S. patent application 13/527,660 (2012); Heismann et al., J. Appl. Phys. 94, 2073–2079 (2003); Park and Kim, J. Korean Phys. Soc. 59, 2709 (2011); Abudurexiti et al., Radiol. Phys. Technol. 3, 127–135 (2010); and Kaewkhao et al., J. Quant. Spectrosc. Radiat. Transfer 109, 1260–1265 (2008)]. This paper describes the tomographic reconstruction of ρ and Z maps of mineralogical samples using the AMTI model. The full model requires precise knowledge of the X-ray energy spectra and calibration of PE and CS constants and exponents of atomic number and energy that were estimated based on fits to simulations and calibration measurements. The estimated ρ and Z images of the samples used in this paper yield average relative errors of 2.62% and 1.19% and maximum relative errors of 2.64% and 7.85%, respectively. Furthermore, we demonstrate that the method accounts for the beam hardening effect in density (ρ) and atomic number (Z) reconstructions to a significant extent.S.J.L., G.R.M., and A.M.K. acknowledge funding through the DigiCore consortium and the support of a linkage grant (LP150101040) from the Australian Research Council and FEI Company

Wasted lives:The social dynamics of shame and youth suicide

Youth suicide is a specific gesture of waste, a throwing away of the gift, and thus it embodies a powerful statement about young people's refusal to live. In this article I suggest that it is a refusal to engage with, and be sustained by, the particular economies of value, morality and meaning that govern identity within contemporary cultural life. From a post-structuralist perspective the metaphors through which suicide comes to be known are examined via indepth interviews conducted with young people ( n = 41) as part of a larger study also involving adults/professionals ( n = 40) within urban and regional communities. Shame figures predominantly in young people's accounts of suicidal experiences and the everyday social relations that govern the expression of emotion. In contrast to the positivist bent of much suicide research and policy, this article argues for the necessity of understanding the social dynamics of shame in relation to the forces of affect that constitute the emergent subjectivities of young people.Griffith Business School, Department of Tourism, Sport and Hotel ManagementFull Tex

The effect of an acute sleep hygiene strategy following a late-night soccer match on recovery of players

© 2016 Taylor & Francis. Elite soccer players are at risk of reduced recovery following periods of sleep disruption, particularly following late-night matches. It remains unknown whether improving sleep quality or quantity in such scenarios can improve post-match recovery. Therefore, the aim of this study was to investigate the effect of an acute sleep hygiene strategy (SHS) on physical and perceptual recovery of players following a late-night soccer match. In a randomised cross-over design, two highly-trained amateur teams (20 players) played two late-night (20:45) friendly matches against each other seven days apart. Players completed an SHS after the match or proceeded with their normal post-game routine (NSHS). Over the ensuing 48 h, objective sleep parameters (sleep duration, onset latency, efficiency, wake episodes), countermovement jump (CMJ; height, force production), YoYo Intermittent Recovery test (YYIR2; distance, maximum heart rate, lactate), venous blood (creatine kinase, urea and c-reactive protein) and perceived recovery and stress markers were collected. Sleep duration was significantly greater in SHS compared to NSHS on match night (P = 0.002, d = 1.50), with NSHS significantly less than baseline (P 0.05); although maximum heart rate during the YYIR2 was significantly higher in NSHS than SHS at 36 h post-match (P = 0.01; d = 0.81). There were no significant differences between conditions for perceptual “overall recovery” (P = 0.47) or “overall stress” (P = 0.17). Overall, an acute SHS improved sleep quantity following a late-night soccer match; albeit without any improvement in physical performance, perceptual recovery or blood-borne markers of muscle damage and inflammation

The Effects of Sleep Loss on Military Physical Performance

© 2019, Springer Nature Switzerland AG. As part of both training and active service, military members can be exposed to prolonged periods of sleep loss. Given the extent of physical and cognitive performances viewed as critical to successful military performance, such sleep disruption may present risk to health and performance. The primary aim of this narrative review was to investigate evidence on the effect of inadequate sleep on measures of aerobic capacity, anaerobic capacity, muscular strength and muscular endurance in military personnel. Sleep loss appears to have the greatest negative impact on aerobic capacity, muscular endurance and military-specific performance in military populations. The findings showed varied results for handgrip strength and anaerobic capacity, with sleep loss inducing a decrease in mean power of the upper body. In comparison to other measures of performance, lower-body muscular strength appeared to be resilient to sleep restriction. However, due to the limited evidence and inter-individual variability in results there is no clear consensus on the specific volume of sleep loss that induces significant or meaningful performance decrements. The difficulties of conducting well-designed and -controlled interventions in military populations are appreciated. However, due to the low quality of reporting and lack of control for confounders (i.e. physical activity, load carriage, prior sleep debt, motivation and energy intake) in the majority of studies, it is difficult to establish the relationship between sleep loss and physical performance in military populations

Subjective wellness, acute: Chronic workloads, and injury risk in college football

© 2019 National Strength and Conditioning Association Sampson, JA, Murray, A, Williams, S, Sullivan, A, and Fullagar, HHK. Subjective wellness, acute: chronic workloads and injury risk in college football. J Strength Cond Res 33(12): 3367-3373, 2019-Acute:chronic workload ratios (ACWRs) are associated with injury risk across team sports. In this study, one season of workload and wellness data from 42 collegiate football players were retrospectively analyzed. Daily 7:21 day exponentially weighted moving average (EWMA) ACWRs were calculated, and z-score fluctuations (“normal,” “better,” and “worse”) in sleep, soreness, energy, and overall wellness were assessed relative to the previous day ACWRs and considered as an interactive effect on the risk of noncontact injury within 0-3 days. Fifty-five noncontact injuries were observed, and injury risks were very likely higher when ACWRs were 2 SDs above (relative risk [RR]: 3.05, 90% confidence interval [CI]: 1.14-8.16) and below (RR: 2.49, 90% CI: 1.11-5.58) the mean. A high ACWR was trivially associated (p, 0.05) with “worse” wellness (r = 20.06, CI: 20.10 to 20.02), muscle soreness (r = 20.07, CI: 20.11 to 20.03), and energy (r = 20.05, CI: 20.09 to 20.01). Feelings of “better” overall wellness and muscle soreness with collectively high EWMA ACWRs displayed likely higher injury risks compared with “normal” (RR: 1.52, 90% CI: 0.91 to 2.54; RR: 1.64, 90% CI: 1.10-2.47) and likely or very likely (RR: 2.36, 90% CI: 0.83 to 674; RR: 2.78, 90% CI: 1.21-6.38) compared with “worse” wellness and soreness, respectively. High EWMA ACWRs increased injury risk and negatively impacted wellness. However, athletes reporting “better” wellness, driven by “better” muscle soreness presented with the highest injury risk when high EWMA ACWRs were observed. This suggests that practitioners are responsive to, and/or athletes are able to self-modulate workload activities

Conductivity tomography at two frequencies

We present a new approach for crosshole radio tomography. Conductivity images of the investigated area are reconstructed from the ratio of the electric field intensities measured at two similar frequencies. The method largely avoids assumptions about the radiation pattern and in-situ intensity of the transmitting antenna, which introduce errors in conventional single-frequency crosshole electromagnetic-absorption tomography. Application of the method to field data achieved an improvement in resolution of anomalies over traditional single-frequency absorption tomography. The dual-frequency method is not a universal approach; it is suitable for moderately conductive media (>0.01 S/m) over the approximate frequency range 1-100 MHz

Impaired sleep and recovery after night matches in elite football players

© 2016 Informa UK Limited, trading as Taylor & Francis Group. ABSTRACT: Despite the perceived importance of sleep for elite footballers, descriptions of the duration and quality of sleep, especially following match play, are limited. Moreover, recovery responses following sleep loss remain unclear. Accordingly, the present study examined the subjective sleep and recovery responses of elite footballers across training days (TD) and both day and night matches (DM and NM). Sixteen top division European players from three clubs completed a subjective online questionnaire twice a day for 21 days during the season. Subjective recall of sleep variables (duration, onset latency, time of wake/sleep, wake episode duration), a range of perceptual variables related to recovery, mood, performance and internal training loads and non-exercise stressors were collected. Players reported significantly reduced sleep durations for NM compared to DM (−157 min) and TD (−181 min). In addition, sleep restfulness (SR; arbitrary scale 1 = very restful, 5 = not at all restful) and perceived recovery (PR; acute recovery and stress scale 0 = not recovered at all, 6 = fully recovered) were significantly poorer following NM than both TD (SR: +2.0, PR: −2.6), and DM (SR: +1.5; PR: −1.5). These results suggest that reduced sleep quantity and quality and reduced PR are mainly evident following NM in elite players

Social recovery and the move beyond deficit models of depression:A feminist analysis of mid-life women's self-care practices

In Australia, like other advanced liberal democracies, the adoption of a recovery orientation was hailed as a major leap forward in mental health policy and service provision. We argue that this shift in thinking about the meaning of recovery requires further analysis of the gendered dimension of self-identity and relationships with the social world. In this article we focus on how mid-life women constructed meaning about recovery through their everyday practices of self-care within the gendered context of depression. Findings from our qualitative research with 31 mid-life women identified how the recovery process was complicated by relapses into depression, with many women critically questioning the limitations of biomedical treatment options for a more relational understanding of recovery. Participant stories revealed important tacit knowledge about recovery that emphasised the process of realising and recognising capacities and self-knowledge. We identify two central themes through which women's tacit knowledge of this changing relation to self in recovery is made explicit: the disciplined self of normalised recovery, redefining recovery and depression. The findings point to the need to reconsider how both recovery discourses and gendered expectations can complicate women's experiences of moving through depression. We argue for a different conceptualisation of recovery as a social practice through which women realise opportunities to embody different 'beings and doings'. A gendered understanding of what women themselves identify is important to their well-being, can contribute to more effective recovery oriented policies based on capability rather than deficit.Full Tex

Sleep and recovery in team sport: Current sleep-related issues facing professional team-sport athletes

© 2015 Human Kinetics, Inc. While the effects of sleep loss on performance have previously been reviewed, the effects of disturbed sleep on recovery after exercise are less reported. Specifically, the interaction between sleep and physiological and psychological recovery in team-sport athletes is not well understood. Accordingly, the aim of the current review was to examine the current evidence on the potential role sleep may play in postexercise recovery, with a tailored focus on professional team-sport athletes. Recent studies show that team-sport athletes are at high risk of poor sleep during and after competition. Although limited published data are available, these athletes also appear particularly susceptible to reductions in both sleep quality and sleep duration after night competition and periods of heavy training. However, studies examining the relationship between sleep and recovery in such situations are lacking. Indeed, further observational sleep studies in team-sport athletes are required to confirm these concerns. Naps, sleep extension, and sleep-hygiene practices appear advantageous to performance; however, future proof-of-concept studies are now required to determine the efficacy of these interventions on postexercise recovery. Moreover, more research is required to understand how sleep interacts with numerous recovery responses in team-sport environments. This is pertinent given the regularity with which these teams encounter challenging scenarios during the course of a season. Therefore, this review examines the factors that compromise sleep during a season and after competition and discusses strategies that may help improve sleep in team-sport athletes