In this paper, we experimentally compare orthogonal frequency-division multiplexing (OFDM) and on-off keying (OOK) modulation in the context of the IEEE 802.15.13-2023 standard at bandwidths up to 50 MHz across a Li-Fi link with distances up to 5 m and a lateral offset up to 51°. Error vector magnitude (EVM) and bit error rate (BER) evaluations confirm that the high peak-to-average power ratio (PAPR) of OFDM limits the achievable transmission distance, but it offers higher data rates due to its higher spectral efficiency. Due to the lower PAPR, OOK-based Pulsed Modulation PHY (PM-PHY) shows a significantly higher link range. As the structure of the PM-PHY is based on OFDM symbols, the two solutions may also be combined to open a wider range of use cases for optical wireless communications.
LINK
Renewable energy sources have an intermittent character that does not necessarily match energy demand. Such imbalances tend to increase system cost as they require mitigation measures and this is undesirable when available resources should be focused on increasing renewable energy supply. Matching supply and demand should therefore be inherent to early stages of system design, to avoid mismatch costs to the greatest extent possible and we need guidelines for that. This paper delivers such guidelines by exploring design of hybrid wind and solar energy and unusual large solar installation angles. The hybrid wind and solar energy supply and energy demand is studied with an analytical analysis of average monthly energy yields in The Netherlands, Spain and Britain, capacity factor statistics and a dynamic energy supply simulation. The analytical focus in this paper differs from that found in literature, where analyses entirely rely on simulations. Additionally, the seasonal energy yield profile of solar energy at large installation angles is studied with the web application PVGIS and an hourly simulation of the energy yield, based on the Perez model. In Europe, the energy yield of solar PV peaks during the summer months and the energy yield of wind turbines is highest during the winter months. As a consequence, three basic hybrid supply profiles, based on three different mix ratios of wind to solar PV, can be differentiated: a heating profile with high monthly energy yield during the winter months, a flat or baseload profile and a cooling profile with high monthly energy yield during the summer months. It is shown that the baseload profile in The Netherlands is achieved at a ratio of wind to solar energy yield and power of respectively Ew/Es = 1.7 and Pw/Ps = 0.6. The baseload ratio for Spain and Britain is comparable because of similar seasonal weather patterns, so that this baseload ratio is likely comparable for other European countries too. In addition to the seasonal benefits, the hybrid mix is also ideal for the short-term as wind and solar PV adds up to a total that has fewer energy supply flaws and peaks than with each energy source individually and it is shown that they are seldom (3%) both at rated power. This allows them to share one cable, allowing “cable pooling”, with curtailment to -for example-manage cable capacity. A dynamic simulation with the baseload mix supply and a flat demand reveals that a 100% and 75% yearly energy match cause a curtailment loss of respectively 6% and 1%. Curtailment losses of the baseload mix are thereby shown to be small. Tuning of the energy supply of solar panels separately is also possible. Compared to standard 40◦ slope in The Netherlands, facade panels have smaller yield during the summer months, but almost equal yield during the rest of the year, so that the total yield adds up to 72% of standard 40◦ slope panels. Additionally, an hourly energy yield simulation reveals that: façade (90◦) and 60◦ slope panels with an inverter rated at respectively 50% and 65% Wp, produce 95% of the maximum energy yield at that slope. The flatter seasonal yield profile of “large slope panels” together with decreased peak power fits Dutch demand and grid capacity more effectively.
DOCUMENT
The massive die-off of the herbivorous sea urchin Diadema antillarum in 1983 and 1984 resulted in phase shifts on Caribbean coral reefs, where macroalgae replaced coral as the most dominant benthic group. Since then, D. antillarum recovery has been slow to non-existent on most reefs. Studying settlement rates can provide insight into the mechanisms constraining the recovery of D. antillarum, while efficient settlement collectors can be used to identify locations with high settlement rates and to collect settlers for restoration practices. The aim of this study was to compare pre and post die-off settlement rates and to determine possible settlement peaks in the Eastern Caribbean island of St. Eustatius. Additionally, we aimed to determine the effectiveness and reproducibility of five different settlement collectors for D. antillarum. D. antillarum settlement around St. Eustatius was highest in May, June and August and low during the rest of the study. Before the die-off, settlement recorded for Curaçao was high throughout the year and was characterized by multiple settlement peaks. Even though peak settlement rates in this study were in the same order of magnitude as in Curaçao before the die-off, overall yearly settlement rates around St. Eustatius were still lower. As no juvenile or adult D. antillarum were observed on the reefs around the settlement collectors, it is likely that other factors are hindering the recovery of the island's D. antillarum populations. Of all five materials tested, bio ball collectors were the most effective and reproducible method to monitor D. antillarum settlement. Panels yielded the least numbers of settlers, which can partly be explained by their position close to the seabed. Settler collection was higher in mid-water layers compared to close to the bottom and maximized when strings of bio balls were used instead of clumps. We recommend research into the feasibility of aiding D. antillarum recovery by providing suitable settlement substrate during the peak of the settlement season and adequate shelter to increase post-settlement survival of settlers. The bio ball collectors could serve as a suitable settlement substrate for this new approach of assisted natural recovery.
MULTIFILE
Background Wheelchair tennis, a globally popular sport, features a professional tour spanning 40 countries and over 160 tournaments. Despite its widespread appeal, information about the physical demands of wheelchair tennis is scattered across various studies, necessitating a comprehensive systematic review to synthesise available data. Objective The aim was to provide a detailed synthesis of the physical demands associated with wheelchair tennis, encompassing diverse factors such as court surfaces, performance levels, sport classes, and sexes. Methods We conducted comprehensive searches in the PubMed, Embase, CINAHL, and SPORTDiscus databases, covering articles from inception to March 1, 2023. Forward and backward citation tracking from the included articles was carried out using Scopus, and we established eligibility criteria following the Population, Exposure, Comparison, Outcome, and Study design (PECOS) framework. Our study focused on wheelchair tennis players participating at regional, national, or international levels, including both juniors and adults, and open and quad players. We analysed singles and doubles matches and considered sex (male, female), sport class (open, quad), and court surface type (hard, clay, grass) as key comparative points. The outcomes of interest encompassed play duration, on-court movement, stroke performance, and physiological match variables. The selected study designs included observational cross-sectional, longitudinal, and intervention studies (baseline data only). We calculated pooled means or mean differences with 95% confidence intervals (CIs) and employed a random-effects meta-analysis with robust variance estimation. We assessed heterogeneity using Cochrane Q and 95% prediction intervals. Results Our literature search retrieved 643 records, with 24 articles meeting our inclusion criteria. Most available information focused on international male wheelchair tennis players in the open division, primarily competing in singles on hard courts. Key findings (mean [95% CI]) for these players on hard courts were match duration 65.9 min [55.0–78.8], set duration 35.0 min [28.2–43.5], game duration 4.6 min [0.92–23.3], rally duration 6.1 s [3.7–10.2], effective playing time 19.8% [18.9–20.7], and work-to-rest ratio 1:4.1 [1:3.7–1:4.4]. Insufficient data were available to analyse play duration for female players. However, for the available data on hard court matches, the average set duration was 34.8 min [32.5–37.2]. International male players on hard court covered an average distance per match of 3859 m [1917–7768], with mean and peak average forward speeds of 1.06 m/s [0.85–1.32] and 3.55 m/s [2.92–4.31], respectively. These players executed an average of 365.9 [317.2–422.1] strokes per match, 200.6 [134.7–299.0] per set, 25.4 [16.7–38.7] per game, and 3.4 [2.6–4.6] per rally. Insufficient data were available for a meta-analysis of female players’ on-court movement and stroke performance. The average and peak heart rates of international male players on hard court were 134.3 [124.2–145.1] and 166.0 [132.7–207.6] beats per minute, and the average match heart rate expressed as a percentage of peak heart rate was 74.7% [46.4–100]. We found no studies concerning regional players or juniors, and only one study on doubles match play. Conclusions While we present a comprehensive overview of the physical demands of wheelchair tennis, our understanding predominantly centres around international male players competing on hard courts in the open division. To attain a more comprehensive insight into the sport’s physical requirements, future research should prioritise the inclusion of data on female and quad players, juniors, doubles, and matches played on clay and grass court surfaces. Such endeavours will facilitate the development of more tailored and effective training programmes for wheelchair tennis players and coaches.
DOCUMENT
The mass adoption of Electric Vehicles (EVs) might raise pressure on the power system, especially during peak hours. Therefore, there is a need for delayed charging. However, to optimize the charging system, the progression of charging from an empty battery until a full battery of the EVs based on realworld data needs to be analyzed. Many researchers currently view this charging profile as a static load and ignore the actual charging behavior during the charging session. This study investigates how different factors influence the charging profile of individual EVs based on real-world data of charging sessionsin the Netherlands, enabling optimization analysis of EV smart charging schemes.
DOCUMENT
Objectives: Aiming to reduce distributed denial-of-service (DDoS) attacks by alerting the consciences of Internet users, this paper evaluates the effectiveness of four warning banners displayed as online ads (deterrent—control, social, informative, and reorienting) and the contents of their two linked landing pages. Methods: We implement a 4 x 2 quasi-experimental design on a self-selected sample of Internet users to measure the engagement generated by the ads and the pages. Engagement is measured on the ads as the ratio of clicks to impressions, and on the pages as percentage of page scrolled, average session duration, video interaction rate, and URLs click rate. Results: Social ads generate significantly more engagement than the rest with low to medium effect sizes. Data reveal no differences in engagement between both landing page designs. Conclusions: Social messages may be a better alternative for engaging with potential cyber offenders than the traditional deterrent messages. Correspondence: Netherlands Institute for the Study of Crime and Law Enforcement (NSCR), De Boelelaan 1077, 1081 HV, Amsterdam, The Netherlands. Email: AMoneva@nscr.n This is a post-peer-review, pre-copyedit version of an article published in Journal of Experimental Criminology. The final authenticated version is available online at: https://link.springer.com/article/10.1007/s11292-022-09504-2
MULTIFILE
The mass adoption of Electric Vehicles (EVs) might raise pressure on the power system, especially during peak hours. Therefore, there is a need for delayed charging. However, to optimize the charging system, the progression of charging from an empty battery to a full battery of the EVs, based on real-world data, needs to be analyzed. Currently, many researchers view this charging profile as a static load and ignore the actual charging behavior during the charging session. However, this study investigates how different factors influence the charging profile of individual EVs based on real-world data of charging sessions in The Netherlands, and thereby enable optimization analysis of EV smart charging schemes.
DOCUMENT
Objectives Patients who underwent corrective surgery for tetralogy of Fallot (TOF) have increased long-term risk of cardiovascular morbidity and mortality. Yet, limited information is available on how to evaluate the risk in this population. Therefore, the aim of this study was to investigate the prognostic value of aerobic exercise capacity, along with other related parameters, at medium-term follow-up in adult patients with tetralogy of Fallot. Methods and results Between 2000 and 2003, 92 adults (age 26.2 ± 7.8 years; 63 male) with corrected TOF or TOF-type morphology underwent a cardiopulmonary exercise test (CPET) until exhaustion and echocardiography. During a mean follow-up of 7.3 ± 1.2 years (range 0.9 to 9.3 years), 2 patients died and 26 patients required at least 1 cardiac-related intervention at a mean age of 28.9 ± 7.9 years. Event-free survival tended to be higher in patients with the classical type of TOF (P = 0.061). At multivariate Cox analysis, age at CPET [hazard ratio (HR): 1.13, P = 0.006], age at correction (HR: 0.82, P = 0.037), right ventricular (RV) function (HR: 4.94, P = 0.001), QRS duration (HR: 1.02, P = 0.007), percentage of predicted peak oxygen uptake (peak VO2%) (HR: 0.96, P = 0.029) and ventilatory effi ciency slope (VE/VCO2 slope) (HR: 1.13, P = 0.021) were signifi cantly related to the incidence of death/cardiac-related intervention during medium follow-up. Conclusions Early corrective surgery and a well-preserved RV are associated with a better outcome in adults with corrected TOF. Furthermore, CPET provides important prognostic information; peak VO2% and VE/VCO2 slope are independent predictors for event-free survival in patients with corrected TOF.
DOCUMENT
IntroductionMechanical power of ventilation, a summary parameter reflecting the energy transferred from the ventilator to the respiratory system, has associations with outcomes. INTELLiVENT–Adaptive Support Ventilation is an automated ventilation mode that changes ventilator settings according to algorithms that target a low work–and force of breathing. The study aims to compare mechanical power between automated ventilation by means of INTELLiVENT–Adaptive Support Ventilation and conventional ventilation in critically ill patients.Materials and methodsInternational, multicenter, randomized crossover clinical trial in patients that were expected to need invasive ventilation > 24 hours. Patients were randomly assigned to start with a 3–hour period of automated ventilation or conventional ventilation after which the alternate ventilation mode was selected. The primary outcome was mechanical power in passive and active patients; secondary outcomes included key ventilator settings and ventilatory parameters that affect mechanical power.ResultsA total of 96 patients were randomized. Median mechanical power was not different between automated and conventional ventilation (15.8 [11.5–21.0] versus 16.1 [10.9–22.6] J/min; mean difference –0.44 (95%–CI –1.17 to 0.29) J/min; P = 0.24). Subgroup analyses showed that mechanical power was lower with automated ventilation in passive patients, 16.9 [12.5–22.1] versus 19.0 [14.1–25.0] J/min; mean difference –1.76 (95%–CI –2.47 to –10.34J/min; P < 0.01), and not in active patients (14.6 [11.0–20.3] vs 14.1 [10.1–21.3] J/min; mean difference 0.81 (95%–CI –2.13 to 0.49) J/min; P = 0.23).ConclusionsIn this cohort of unselected critically ill invasively ventilated patients, automated ventilation by means of INTELLiVENT–Adaptive Support Ventilation did not reduce mechanical power. A reduction in mechanical power was only seen in passive patients.Study registrationClinicaltrials.gov (study identifier NCT04827927), April 1, 2021URL of trial registry recordhttps://clinicaltrials.gov/study/NCT04827927?term=intellipower&rank=1
MULTIFILE
Objective: To investigate the effects of a school-based once-a-week sports program on physical fitness, physical activity, and cardiometabolic health in children and adolescents with a physical disability. Methods: This controlled clinical trial included 71 children and adolescents from four schools for special education [mean age 13.7 (2.9) years, range 8–19, 55% boys]. Participants had various chronic health conditions including cerebral palsy (37%), other neuromuscular (44%), metabolic (8%), musculoskeletal (7%), and cardiovascular (4%) disorders. Before recruitment and based on the presence of school-based sports, schools were assigned as sport or control group. School-based sports were initiated and provided by motivated experienced physical educators. The sport group (n = 31) participated in a once-a-week school-based sports program for 6 months, which included team sports. The control group (n = 40) followed the regular curriculum. Anaerobic performance was assessed by the Muscle Power Sprint Test. Secondary outcome measures included aerobic performance, VO2 peak, strength, physical activity, blood pressure, arterial stiffness, body composition, and the metabolic profile. Results: A significant improvement of 16% in favor of the sport group was found for anaerobic performance (p = 0.003). In addition, the sport group lost 2.8% more fat mass compared to the control group (p = 0.007). No changes were found for aerobic performance, VO2 peak, physical activity, blood pressure, arterial stiffness, and the metabolic profile. Conclusion: Anaerobic performance and fat mass improved following a school-based sports program. These effects are promising for long-term fitness and health promotion, because sports sessions at school eliminate certain barriers for sports participation and adding a once-a-week sports session showed already positive effects for 6 months.
DOCUMENT
