• A bibliographic review of medicine and science research in DanceSport

      Wyon, Matthew; Riding-McCabe, T; Ambegaonkar, J; Redding, E (Science & Medicine, 2013-06)
      DanceSport is the competitive form of ballroom dancing, and even though it has more participants worldwide than ballet and modern dance, there is less peer-reviewed research. A review was conducted to identify all relevant literature to help researchers and clinicians gain an enhanced understanding of dancesport. Eight databases were searched, with 34 articles found in topics including participation motives, psychology, exercise physiology, fitness training, injuries and injury prevention, biomechanics, menstrual dysfunction, and substance use. Our results indicate that researchers have been inconsistently recording and reporting anthropometric and dancesport data; for example, 31 studies separated participants by gender, 21 included the competition classification of dancers, 19 reported which style of dancesport participants competed in, and 13 described the participants as a dance couple. Common injuries affected the neck, shoulder, spine, knee, lower leg, and foot. Dancesport is in the very heavy to extremely heavy category in energy expenditure (mean heart rate: male 175.2 ± 10.7, female 178.6 ± 8.6 bpm) and utilizes both aerobic and anaerobic energy systems. Alpha-beta and heart rate variability intervention techniques are reported to successfully enhance performance in dancers. Dancesport participants also appear less likely to smoke cigarettes, but have little knowledge about anti-doping rules. During events, professionals danced farther (30 m) and faster (0.3 m/sec) than junior dancers. Female competitors were more likely to be eumenorrheic. Dancesport is a physically and mentally demanding competitive sport, but there is a need to standardize measurements in future studies to allow comparison.
    • A brief exposure to moderate passive smoke increases metabolism and thyroid hormone secretion.

      Metsios, Giorgos S.; Flouris, Andreas D.; Jamurtas, Athanasios Z.; Carrillo, A.E.; Kouretas, Dimitris; Germenis, A.E.; Gourgoulianis, K.; Kiropoulos, T.; Tzatzarakis, M.N.; Tsatsakis, A.M.; et al. (The Endocrine Society/HighWire Press, 2007)
      CONTEXT: Active smoking influences normal metabolic status and thyroid function. OBJECTIVE: The objective was to assess experimentally the effects of 1 h of moderate passive smoking in a controlled simulated bar/restaurant environment on the metabolism and thyroid hormone levels in healthy nonsmokers. PARTICIPANTS: Eighteen (nine females, nine males) healthy individuals (mean +/- sd: age, 25.3 +/- 3.1 yr; height, 174.0 +/- 10.1 cm; weight, 65.2 +/- 13.7 kg) participated in the study. DESIGN: In repeated-measures randomized blocks, participants visited the laboratory on 2 consecutive days. In the experimental condition, they were exposed to 1 h of moderate passive smoking at a carbon monoxide concentration of 23 +/- 1 ppm in an environmental chamber, whereas in the control condition participants remained in the same chamber for 1 h breathing normal atmospheric air. MAIN OUTCOME MEASURES: In both conditions, cotinine serum and urine levels, resting energy expenditure (REE), as well as concentration of T3, free T4, and TSH were assessed before participants entered the chamber and immediately after their exit. Heart rate and blood pressure were tested in 10-min intervals during all REE assessments. RESULTS: The mean +/- sd difference of serum and urine cotinine levels (-0.27 +/- 3.94 vs. 14.01 +/- 6.54 and 0.05 +/- 2.07 vs. 7.23 +/- 3.75, respectively), REE (6.73 +/- 98.06 vs. 80.58 +/- 120.91) as well as T3 and free T4 (0.05 +/- 0.11 vs. 0.13 +/- 0.12 and 0.02 +/- 0.15 vs. 0.22 +/- 0.20) were increased in the experimental compared with the control condition at baseline and follow-up (P < 0.05). No statistically significant variation was observed in the mean difference of the remaining parameters (P > 0.05). Serum and urine cotinine values were linearly associated with REE (P < 0.05). CONCLUSION: One hour of passive smoking at bar/restaurant levels is accompanied by significant increases in metabolism and thyroid hormone levels.
    • A calculated risk

      Pitt, Linsey (University of Wolverhampton, 2003)
    • A comparative study on the clinical decision making processes of nurse practitioners versus medical doctors using scenarios within a secondary care environment

      Barratt, Julian; Moorley, Calvin; Thompson, Stephen (Wiley, 2017-04-07)
      Subjects This study was conducted from May 2012 to January 2013.Aim To investigate the decision-making skills of secondary care nurse practitioners compared to those of medical doctors.Background A literature review was conducted, searching for articles published from 1990 to 2012. The review found that nurse practitioners are key to the modernisation of the National Health Service. Studies have shown that compared to doctors, nurse practitioners can be efficient and cost-effective in consultations.Design Qualitative research design. Methods The information processing theory and think-aloud approach were used to understand the cognitive processes of 10 participants (5 doctors and 5 nurse practitioners). One nurse practitioner was paired with one doctor from the same speciality, and they were compared using a structured scenario-based interview. To ensure that all critical and relevant cues were covered by the individual participating in the scenario, a reference model was used to measure the degree of successful diagnosis, management and treatment.Results The data were processed for 5 months, from July to November 2012. The two groups of practitioners differed in the number of cue acquisitions obtained in the scenarios. In our study, nurse practitioners took three minutes longer to complete the scenarios. Conclusion This study suggests that nurse practitioner consultations are comparable to those of medical doctors within a secondary care environment in terms of correct diagnoses and therapeutic treatments. The information processing theory highlighted that both groups of professionals had similar models for decision-making processes.
    • A comparison of developmental coordination disorder prevalence rates in Canadian and Greek children.

      Tsiotra, Georgia D.; Flouris, Andreas D.; Koutedakis, Yiannis; Faught, Brent E.; Nevill, Alan M.; Lane, Andrew; Skenteris, Nicolaos (Elsevier BV, 2006)
      We examined whether lifestyle differences between Canadian and Greek children may be reflected in Developmental Coordination Disorder (DCD) prevalence rates. Data revealed that the relatively inactive Greek children demonstrated higher DCD prevalence rates compared to the Canadian sample and exhibited a greater risk for clinical obesity and low cardiorespiratory fitness.
    • A comparison of strength and stretch interventions on active and passive ranges of movement in dancers: a randomized controlled trial.

      Wyon, Matthew A.; Smith, Anna; Koutedakis, Yiannis (Lippincott Williams & Wilkins, 2013-11)
      The majority of stretching interventional research has focused on the development of a muscle's passive range of movement (PROM). Active range of movement (AROM) refers to the functional range of movement (ROM) available to the participant and provides a better insight into the relationship between muscular antagonistic pairings. The purpose of this study was to assess the effect of 3 strengthening or stretching interventions on hip and lower limb active (AROM) and passive (PROM) ranges of movement. Thirty-nine female dance students (17 ± 0.52 years; 61.7 ± 8.48 kg; 164.4 ± 5.49 cm) volunteered. They were randomly divided into 3 groups, strength training (n = 11); low-intensity stretching (n = 13); moderate-intensity or high-intensity stretching (n = 11). Four dancers withdrew during the study. All groups carried out a 6-week intervention. The strength training group focused on end of range hip flexor strength; the low-intensity and moderate-intensity stretch group carried out a series of stretches at 3/10 and 8/10 perceived exertion, respectively. Active range of movement and PROM were measured preintervention and postintervention using 2-d video analysis. Repeated measures analysis indicated that although all 3 groups improved their PROM during the experimental period (range increase: 9-200 p < 0.01), no significant differences were found between the groups. For AROM, both the strength training and the low-intensity stretch groups revealed significant improvements in ROM (range increase: 20-300) compared with the moderate-intensity or high-intensity stretch group (p < 0.01). The present data show that interventions based on strengthening agonist muscles or decreasing the resistance of antagonist muscles through low-intensity stretching are beneficial in the development of both active and passive ranges of movement and provide functional training techniques that are often over looked in favor of the more conservative moderate-intensity stretching programs.
    • A comparison of two stretching modalities on lower-limb range of motion measurements in recreational dancers.

      Wyon, Matthew A.; Felton, Lee; Galloway, Shaun (National Strength and Conditioning Association, 2009-10)
      Most stretching techniques are designed to place a "stress" on the musculoskeletal unit that will increase its resting length and range of motion (ROM). Twenty-four adolescent dancers participated in a 6-week intervention program that compared low-intensity stretching (Microstretching) with moderate-intensity static stretching on active and passive ranges of motion. Microstretching is a new modality that reduces the possibility of the parasympathetic system being activated. Repeated measures analysis indicated changes in ROM over the intervention period (p < 0.05), with the Microstretching group demonstrating greater increases in passive and active ROM than the static stretch group (p < 0.01); there was no noted bilateral differences in ROM. The results from this study agree with past studies that have found that stretching increases the compliance of any given muscle and therefore increases the range of motion. One main finding of the present study was that throughout a 6-week training program very-low-intensity stretching had a greater positive effect on lower-limb ROM than moderate-intensity static stretching. The most interesting aspect of the study was the greater increase in active ROM compared to passive ROM by the Microstretching group. This suggests that adaptation has occurred within the muscle itself to a greater extent than in structures of the hip joint. Practical application for this technique suggests it is beneficial as a postexercise modality that potentially has a restorative component.
    • A conversation analysis of asking about disruptions in method of levels psychotherapy

      Cannon, Caitlyn; Meredith, Joanne; Speer, Susan; Mansell, Warren (Wiley, 2019-06-17)
      Background: Method of Levels (MOL) is a cognitive therapy with an emerging evidence base. It is grounded in Perceptual Control Theory and its transdiagnostic nature means techniques are widely applicable and not diagnosis-specific. This paper contributes to psychotherapy process research by investigating a key technique of MOL, asking about disruptions, and in doing so aims to explore how the technique works and aid the understanding of related techniques in other psychotherapies. Method: Conversation Analysis (CA) is applied to asking about disruptions in twelve real-life therapeutic interactions. Findings: Analyses explore how and when therapists ask about disruptions, with examples presented according to their degree of adherence to the MOL approach. The majority of identified instances project responses consistent with MOL aims; encouraging further talk, focused on the client’s problem, and with a shift to meta-level commentary. Also presented are examples of therapist and client influence on disruptions. Conclusion: The paper provides support for a number of MOL practices, with clinical implications and links to other psychotherapies highlighted.
    • A critical process: developing skills in conducting a critical review of the literature.

      Mason, Andrea (University of Wolverhampton, 2004)
      White & Taylor (2002) suggest that for many years, the United Kingdom Central Council for Nursing, Midwifery and Health Visiting (UKCC), has sought to promote the development of research knowledge and skills in Registered nurses. One aspect of this is the critical review of published literature. This can be viewed as an activity which spans across both undergraduate and post graduate work (Morris & Maynard 2000). It has also been suggested that such skills are necessary attributes of independent learning (Patterson et al., 2002). However, there is a view that constructing a critical review of published literature is challenging and that it can present difficulties for students (Carnwell & Daly 2001). This view supports expert opinion within the School of Health, where academics have identified that student nurses appear to experience difficulties in some or all of the stages of the process of critically reviewing published literature. The aim of the project was to develop an online study package for student nurses and midwives, aimed at developing skills in conducting a critical review of literature. The outcome of the project is the development of an interactive topic within the university virtual learning environment, Wolverhampton On-line Learning Framework (WOLF) which focuses on the stages of conducting a critical review of published articles.
    • A Cross-Cultural Comparison of Health Behaviors between Saudi and British Adolescents Living in Urban Areas: Gender by Country Analyses.

      Al-Hazzaa, Hazzaa M; Al-Nakeeb, Yahya; Duncan, Michael J; Al-Sobayel, Hana I; Abahussain, Nada A; Musaiger, Abdulrahman O; Lyons, Mark; Collins, Peter; Nevill, Alan M. (MDPI, 2013-12)
      This study investigated the cross-cultural differences and similarity in health behaviors between Saudi and British adolescents. A school-based cross-sectional study was conducted at four cities in Saudi Arabia (Riyadh and Al-Khobar; N = 1,648) and Britain (Birmingham and Coventry; N = 1,158). The participants (14-18 year-olds) were randomly selected using a multistage stratified cluster sampling technique. Measurements included anthropometric, screen time, validated physical activity (PA) questionnaire and dietary habits. The overweight/obesity prevalence among Saudi adolescents (38.3%) was significantly (p < 0.001) higher than that found among British adolescents (24.1%). The British adolescents demonstrated higher total PA energy expenditure than Saudi adolescents (means ± SE = 3,804.8 ± 81.5 vs. 2,219.9 ± 65.5 METs-min/week). Inactivity prevalence was significantly (p < 0.001) higher among Saudi adolescents (64%) compared with that of British adolescents (25.5%). The proportions of adolescents exceeding 2 h of daily screen time were high (88.0% and 90.8% among Saudis and British, respectively). The majority of Saudi and British adolescents did not have daily intakes of breakfast, fruit, vegetables and milk. MANCOVA showed significant (p < 0.05) gender by country interactions in several lifestyle factors. There was a significant (p < 0.001) gender differences in the ratio of physical activity to sedentary behaviors. In conclusion, Saudi and British adolescents demonstrated some similarities and differences in their PA levels, sedentary behaviors and dietary habits. Unhealthy lifestyle behaviors among adolescents appear to be a cross-cultural phenomenon.
    • A field-test battery for elite, young soccer players.

      Hulse, M A; Morris, J G; Hawkins, R D; Hodson, A; Nevill, Alan M.; Nevill, M E (2013-04)
      The validity and reliability of a battery of field-based performance tests was examined. The opinions of coaches, fitness professionals and players (n=170, 172 and 101 respectively) on the importance of performance testing were established using a questionnaire. On 2 occasions, separated by 7 days, 80 elite, young soccer players (mean±SD [and range]: age 13.2±2.6 [8.9-19.1] years; stature 1.59±0.18 m [1.32-1.91]; body mass 50.6±17.1 [26.5-88.7] kg) completed a battery of field-based tests comprised of heart rate response to a submaximal Multi-stage fitness test, 3 types of vertical jump, sprints over 10 and 20 m, and an agility test. Physical performance testing was considered important by coaches (97%), fitness professionals (94%) and players (83%). The systematic bias ratio and the random error components of the 95% ratio limits of agreement for the first and second tests, for the U9-U11 vs. U12-U14 vs. U15-U18 age groups, were [Systematic bias (*/÷ ratio limits)]: Heart rate (Level 5): 0.983 (*/÷ 1.044) vs. 0.969 (*/÷ 1.056) vs. 0.983 (*/÷ 1.055); Rocket jump: 0998 (*/÷ 1.112) vs. 0.999 (*/÷ 1.106) vs. 0.996 (*/÷ 1.093); 10 m sprint: 0.997 (*/÷ 1.038) vs. 0.994 (*/÷ 1.033) vs. 0.994 (*/÷ 1.038); Agility test: 1.010 (*/÷1.050) vs. 1.014 (*/÷1.050) vs. 1.002 (*/÷1.053). All tests, except heart rate recovery from the Multi-stage fitness test, were able to distinguish between different ability and age groups of players (p<0.05). Thus, the field-test battery demonstrated logical and construct validity, and was shown to be a reliable and objective tool for assessing elite, young soccer players.
    • A History of World Cup Posters 1930-2014

      Williams, Jean (Berg, 2017)
      The historical development of official World Cup posters provides a fascinating means of considering the growth of the world’s most popular sport. There are important continuities with the history of the modern Olympic Games, which were inaugurated in 1896 in Athens. From 1908 the Olympic Games staged a small but influential football tournament, out of which the World Cup eventually developed. At the London 1908 Olympic Games, the Football Association (FA) organised the competition, though it remained contested whether representative players were entirely amateur. Formed in 1863, the FA had agreed to tolerate professionalism since 1885, and the entirely professional Football League was formed in 1888. Friendly international football rivalries against other national teams has begun in 1872, and were instantly popular with spectators and the media alike.
    • A large scale examination of the effectiveness of anonymous marking in reducing group performance differences in higher education assessment

      Hinton, Danny; Higson, Helen (PLOS, 2017-08-15)
      The present research aims to more fully explore the issues of performance differences in higher education assessment, particularly in the context of a common measure taken to address them. The rationale for the study is that, while performance differences in written examinations are relatively well researched, few studies have examined the efficacy of anonymous marking in reducing these performance differences, particularly in modern student populations. By examining a large archive (N = 30674) of assessment data spanning a twelve-year period, the relationship between assessment marks and factors such as ethnic group, gender and socio-environmental background was investigated. In particular, analysis focused on the impact that the implementation of anonymous marking for assessment of written examinations and coursework has had on the magnitude of mean score differences between demographic groups of students. While group differences were found to be pervasive in higher education assessment, these differences were observed to be relatively small in practical terms. Further, it appears that the introduction of anonymous marking has had a negligible effect in reducing them. The implications of these results are discussed, focusing on two issues, firstly a defence of examinations as a fair and legitimate form of assessment in Higher Education, and, secondly, a call for the re-examination of the efficacy of anonymous marking in reducing group performance differences.
    • A low-protein, high-carbohydrate diet increases browning in perirenal adipose tissue but not in inguinal adipose tissue

      Pereira, Mayara P.; Ferreira, Laís A.A.; da Silva, Flávia H.S.; Christoffolete, Marcelo A.; Metsios, George S.; Chaves, Valéria E.; de França, Suélem A.; Damazo, Amílcar S.; Flouris, Andreas D.; Kawashita, Nair H. (Elsevier, 2017-05-31)
      Objective The aim of this study was to evaluate the browning and origin of fatty acids (FAs) in the maintenance of triacylglycerol (TG) storage and/or as fuel for thermogenesis in perirenal adipose tissue (periWAT) and inguinal adipose tissue (ingWAT) of rats fed a low-protein, high-carbohydrate (LPHC) diet. Methods LPHC (6% protein, 74% carbohydrate) or control (C; 17% protein, 63% carbohydrate) diets were administered to rats for 15 d. The tissues were stained with hematoxylin and eosin for histologic analysis. The content of uncoupling protein 1 (UCP1) was determined by immunofluorescence. Levels of T-box transcription factor (TBX1), PR domain containing 16 (PRDM16), adipose triacylglycerol lipase (ATGL), hormone-sensitive lipase, lipoprotein lipase (LPL), glycerokinase, phosphoenolpyruvate carboxykinase (PEPCK), glucose transporter 4, β3-adrenergic receptor (AR), β1-AR, protein kinase A (PKA), adenosine-monophosphate-activated protein kinase (AMPK), and phospho-AMPK were determined by immunoblotting. Serum fibroblast growth factor 21 (FGF21) was measured using a commercial kit (Student's t tests, P < 0.05). Results The LPHC diet increased FGF21 levels by 150-fold. The presence of multilocular adipocytes, combined with the increased contents of UCP1, TBX1, and PRDM16 in periWAT of LPHC-fed rats, suggested the occurrence of browning. The contents of β1-AR and LPL were increased in the periWAT. The ingWAT showed higher ATGL and PEPCK levels, phospho-AMPK/AMPK ratio, and reduced β3-AR and PKA levels. Conclusion These findings suggest that browning occurred only in the periWAT and that higher utilization of FAs from blood lipoproteins acted as fuel for thermogenesis. Increased glycerol 3-phosphate generation by glyceroneogenesis increased FAs reesterification from lipolysis, explaining the increased TG storage in the ingWAT.
    • A multicentre community-based study of dementia cases and subcases in older people in China--the GMS-AGECAT prevalence and socio-economic correlates.

      Chen, Ruoling; Ma, Ying; Wilson, Ken; Hu, Zhi; Sallah, David; Wang, Jiaji; Fan, Lihua; Chen, Ruo-Li; Copeland, John R (Wiley, 2011-09-21)
      Previous studies indicated overall relatively low prevalence of dementia in older people in China, which may be biased by studied samples or methods. We determined the prevalence of dementia cases and subcases in China and examined their socio-economic correlates. Using the Geriatric Mental State interview, we examined random samples of 2917 participants aged ≥ 65 years in urban and rural Anhui, China in 2001-2003, and 3327 in four other provinces in 2008-2009. Dementia cases and subcases were diagnosed by Geriatric Mental State-Automated Geriatric Examination for Computer Assisted Taxonomy. Age-standardised prevalence for cases and subcases of dementia in the Anhui elders was 7.20% (95%CI 6.29%-8.20%) and 10.5% (9.38%-11.6%), and in the four provinces, 9.86% (8.80%-10.9%) and 8.51% (7.51%-9.52%). The matched figures among the participants who were literate were 3.05% (2.08%-4.02%) and 10.0% (8.38%-11.6%), and 4.92% (3.89%-5.96%) and 6.76% (5.55%-7.96%), respectively. There were higher prevalence rates of dementia cases and subcases in the rural elders than in the urban. Both the Anhui and four-province studies showed an obvious association of dementia with higher and lower incomes among elders who had lower educational levels or had the lowest occupational class. The highest risk of dementia was found in those who were illiterate but had the highest income or had the job of business/nonmanual labouring. People in China have a higher prevalence of dementia than previously reported. Its U-shaped relationship with income and the excess subcases prevalence predicates a significant burden of disease, both now and for the future, suggesting preventive strategy for dementia in China.
    • A multidisciplinary approach to talent identification in soccer

      Reilly, Thomas; Williams, A. Mark; Nevill, Alan M.; Franks, A. (Taylor & Francis Ltd, 2000-09)
      The requirements for soccer play are multifactorial and distinguishing characteristics of elite players can be investigated using multivariate analysis. The aim of the present study was to apply a comprehensive test battery to young players with a view to distinguishing between elite and sub-elite groups on the basis of performance on test items. Thirty-one (16 elite, 15 sub-elite) young players matched for chronological age (15± 16 years) and body size were studied. Test items included anthropometric (n = 15), physiological (n = 8), psychological (n = 3) and soccer-specific skills (n = 2) tests. Variables were split into separate groups according to somatotype, body composition, body size, speed, endurance, performance measures, technical skill, anticipation, anxiety and task and ego orientation for purposes of univariate and multivariate analysis of variance and stepwise discriminant function analysis. The most discriminating of the measures were agility, sprint time, ego orientation and anticipation skill. The elite players were also significantly leaner, possessed more aerobic power (9.0 ± 1.7 vs 55.5 ± 3.8 ml´kg- 1 ´min- 1) and were more tolerant of fatigue (P < 0.05). They were also better at dribbling the ball, but not shooting. We conclude that the test battery used may be useful in establishing baseline reference data for young players being selected onto specialized development programmes.
    • A National Learning Entitlement: Moving Beyond University Tuition Fees

      Schuller, Tom; Tuckett, Alan; Wilson, Tom (LLAKES Centre, UCL Institute of Education, 2018-01)
      The paper sets out a proposal for a National Learning Entitlement as a means of supporting all post-secondary students. The proposal takes the debate beyond the current narrow focus on university education and student debt, to a broader and more inclusive system which would encourage learning at all ages by a diverse range of students, at a lower cost than the abolition of university fees. The proposal is for a national learning entitlement which would enable free access to publicly provided, or publicly recognised, education and training for the equivalent of two years for all those aged 18 and above. It would be valid for further and adult education colleges as well as higher education. The entitlement would be pitched at around £5K per year, but could be used flexibly for part-time study, and spread over a lifetime. By going beyond university students the NLE spreads public subsidy far more equitably and efficiently. It brings into play the other 50% of the youth cohort, as well as adults who have missed out first time round. It strongly encourages diversity of provision and so matches supply better to demand. It wins on fairness, efficiency and future orientation.
    • A new quality of life consultation template for patients with venous leg ulceration

      Green, J.; Jester, R.; McKinley, R.; Pooler, A.; Mason, S.; Redsell, S.; Lecturer, School of Nursing and Midwifery, Keele University, Staffordshire, ST4 6QG; Professor, Faculty of Health and Social Care, London South Bank University, London, SE1 0AA.; Professor of Education in General Practice, Keele University Medical School, Staffordshire, ST5 5BG.; Lecturer, School of Nursing and Midwifery, Keele University, Staffordshire, ST4 6QG; et al. (MA Healthcare Ltd, 2015-03-02)
      OBJECTIVE: Chronic venous leg ulcers (CVLUs) are common and recurrent, however, care for patients predominantly has a focus which overlooks the impact of the condition on quality of life. The aim of this study was to develop a simple, evidence-based consultation template, with patients and practitioners, which focuses consultations on quality of life themes. METHOD: A nominal group was undertaken to develop a new consultation template for patients with CVLUs based on the findings of earlier qualitative study phases. RESULTS: A user-friendly two-sided A4 template was designed to focus nurse-patient consultations on the quality of life challenges posed by CVLUs. CONCLUSION: CVLUs impact negatively on the quality of life of the patient but this receives inadequate attention during current consultations. This new template will help to ensure that key concerns are effectively raised, explored and addressed during each consultation. DECLARATION OF INTEREST: The NHS West Midlands Strategic Health Authority funded this study. The authors have no conflicts of interest to declare.