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Gender differences in competitiveness have been hypothesized as a potential explanation for gender differences in education and labor market outcomes. We examine the predictive power of a standard laboratory experimental measure of competitiveness for the later important choice of academic track of secondary school students in the Netherlands. Although boys and girls display similar levels of academic ability, boys choose substantially more prestigious academic tracks, where more prestigious tracks are more math- and science-intensive. Our experimental measure shows that boys are also substantially more competitive than girls. We find that competitiveness is strongly positively correlated with choosing more prestigious academic tracks even conditional on academic ability. Most important, we find that the gender difference in competitiveness accounts for a substantial portion (about 20%) of the gender difference in track choice.

This document presents the recommendations developed by the IOC Medical and Scientific Commission and several international federations (IF) on the protection of athletes competing in the heat. It is based on a working group, meetings, field experience and a Delphi process. The first section presents recommendations for event organisers to monitor environmental conditions before and during an event; to provide sufficient ice, shading and cooling; and to work with the IF to remove regulatory and logistical limitations. The second section summarises recommendations that are directly associated with athletes’ behaviours, which include the role and methods for heat acclimation; the management of hydration; and adaptation to the warm-up and clothing. The third section explains the specific medical management of exertional heat stroke (EHS) from the field of play triage to the prehospital management in a dedicated heat deck, complementing the usual medical services. The fourth section provides an example for developing an environmental heat risk analysis for sport competitions across all IFs. In summary, while EHS is one of the leading life-threatening conditions for athletes, it is preventable and treatable with the proper risk mitigation and medical response. The protection of athletes competing in the heat involves the close cooperation of the local organising committee, the national and international federations, the athletes and their entourages and the medical team.

Thirty years into its development, additive manufacturing has become a mainstream manufacturing process. Additive manufacturing build up parts by adding materials one layer at a time based on a computerized 3D solid model. It does not require the use of fixtures, cutting tools, coolants, and other auxiliary resources. It allows design optimization and the producing of customized parts on-demand. Its advantages over conventional manufacturing have captivated the imagination of the public, reflected in recent mainstream publications that call additive manufacturing “the third industrial revolution.” This paper reviews the societal impact of additive manufacturing from a technical perspective. Abundance of evidences were found to support the promises of additive manufacturing in the following areas: (1) customized healthcare products to improve population health and quality of life, (2) reduced environmental impact for manufacturing sustainability, and (3) simplified supply chain to increase efficiency and responsiveness in demand fulfillment. In the mean time, the review also identified the need for further research in the areas of life-cycle energy consumption evaluation and potential occupation hazard assessment for additive manufacturing.

Physical activity provides many health benefits, yet few children meet the physical activity recommendations. In school-age children, low proficiency in fundamental movement skills (FMS) is associated with low physical activity (PA). It is unknown if the same relationship exists in pre-schoolers (aged 3-5 years). The aims of this review were to firstly evaluate interventions for improving FMS and PA levels in children aged 3-5 years and 5-12 years, and secondly to determine, where possible, if there is a similar relationship between change in FMS and change in PA across both age groups. A systematic search of electronic databases was conducted up until 20 July 2017. Controlled trials that implemented an FMS/PA intervention and measured PA levels (objective/subjective) and FMS (objective) in healthy children between the ages of 3 and 12 years were included. Sub-analysis was conducted based on the type of intervention (teacher-led [TL] or teacher educated), sessions per week (( 3 or )= 3) and age group. Search terms yielded 17,553 articles, of which 18 met the inclusion criteria. There was significant improvement in FMS with TL interventions of three or more sessions per week (standardised mean difference = 0.23 [0.11-0.36]; p = 0.0002). In TL interventions, there was a strong negative correlation between moderate-vigorous physical activity (MVPA) and sedentary behaviour (SB) (r = - 0.969; p = 0.031). There are limited studies measuring both FMS and PA following an FMS intervention, especially in school-aged children. Results indicate that training pre-schoolers at least three times a week in FMS can improve proficiency, increase intensity of PA, and reduce SB, possibly helping to reduce the burden of childhood obesity and its associated health risks. (Autor).

Printed electronics is a revolutionary technology aimed at unconventional electronic device manufacture on plastic foils, and will probably rely on polymeric semiconductors for organic thin-film transistor (OTFT) fabrication. In addition to having excellent charge-transport characteristics in ambient conditions, such materials must meet other key requirements, such as chemical stability, large solubility in common solvents, and inexpensive solution and/or low-temperature processing. Furthermore, compatibility of both p-channel (hole-transporting) and n-channel (electron-transporting) semiconductors with a single combination of gate dielectric and contact materials is highly desirable to enable powerful complementary circuit technologies, where p- and n-channel OTFTs operate in concert. Polymeric complementary circuits operating in ambient conditions are currently difficult to realize: although excellent p-channel polymers are widely available, the achievement of high-performance n-channel polymers is more challenging. Here we report a highly soluble (∼60 g l -1 ) and printable n-channel polymer exhibiting unprecedented OTFT characteristics (electron mobilities up to ∼0.45–0.85 cm 2  V -1  s -1 ) under ambient conditions in combination with Au contacts and various polymeric dielectrics. Several top-gate OTFTs on plastic substrates were fabricated with the semiconductor-dielectric layers deposited by spin-coating as well as by gravure, flexographic and inkjet printing, demonstrating great processing versatility. Finally, all-printed polymeric complementary inverters (with gain 25–65) have been demonstrated. Printed transistors Printed electronics devices show great potential for cheap consumer and health-care products and new applications are rapidly emerging. But device applications are limited by the fact that the plastic semiconductors currently available are almost exclusively 'hole-transporting' materials that operate via the conduction of positive charges. If an electron-transporting equivalent can be found — retaining good electrical transport properties, chemical stability and ease of processing — then it would be possible to use it in tandem with the existing plastic semiconductors to produce yet more powerful devices. Such combinations are known as 'complementary' circuitry. A team working at the Polyera Corporation labs in the United States and at BASF in Germany has produced a new material that achieves that goal. It is a highly soluble electron-transporting plastic semiconductor that exhibits unprecedented device performance, and is compatible with a broad range of printing and processing technologies. A range of plastic semiconductors have been developed that have the combination of physical and chemical properties required to enable printable electronic circuitry, but these are almost exclusively 'hole transporting' materials. If an electron-transporting equivalent could be found, it could be combined with the existing classes of materials to produce yet more powerful devices. This paper reports the development of a such a material: the electron-transporting plastic semiconductor exhibits unprecedented device performance, and is compatible with a broad range of printing and processing technologies.

The prohibitive cost of platinum for catalyzing the cathodic oxygen reduction reaction (ORR) has hampered the widespread use of polymer electrolyte fuel cells. We describe a family of non-precious metal catalysts that approach the performance of platinum-based systems at a cost sustainable for high-power fuel cell applications, possibly including automotive power. The approach uses polyaniline as a precursor to a carbon-nitrogen template for high-temperature synthesis of catalysts incorporating iron and cobalt. The most active materials in the group catalyze the ORR at potentials within ~60 millivolts of that delivered by state-of-the-art carbon-supported platinum, combining their high activity with remarkable performance stability for non-precious metal catalysts (700 hours at a fuel cell voltage of 0.4 volts) as well as excellent four-electron selectivity (hydrogen peroxide yield <1.0%).

Aqueous lithium-ion batteries may solve the safety problem associated with lithium-ion batteries that use highly toxic and flammable organic solvents, and the poor cycling life associated with commercialized aqueous rechargeable batteries such as lead-acid and nickel-metal hydride systems. But all reported aqueous lithium-ion battery systems have shown poor stability: the capacity retention is typically less than 50% after 100 cycles. Here, the stability of electrode materials in an aqueous electrolyte was extensively analysed. The negative electrodes of aqueous lithium-ion batteries in a discharged state can react with water and oxygen, resulting in capacity fading upon cycling. By eliminating oxygen, adjusting the pH values of the electrolyte and using carbon-coated electrode materials, LiTi 2 (PO 4 ) 3 /Li 2 SO 4 /LiFePO 4 aqueous lithium-ion batteries exhibited excellent stability with capacity retention over 90% after 1,000 cycles when being fully charged/discharged in 10 minutes and 85% after 50 cycles even at a very low current rate of 8 hours for a full charge/discharge offering an energy storage system with high safety, low cost, long cycling life and appropriate energy density. Aqueous lithium-ion batteries have great potential as stationary power sources, but they have had problems with poor stability. A significant improvement in their cycling stability has been achieved by eliminating oxygen, adjusting the electrolyte pH values, and using a carbon-coated electrode material.

We describe the recent experimental progress in the control of spontaneous emission by manipulating optical modes with photonic crystals. It has been clearly demonstrated that the spontaneous emission from light emitters embedded in photonic crystals can be suppressed by the so-called photonic bandgap, whereas the emission efficiency in the direction where optical modes exist can be enhanced. Also, when an artificial defect is introduced into the photonic crystal, a photonic nanocavity is produced that can interact with light emitters. Cavity quality factors, or Q factors, of up to 2 million have been realized while maintaining very small mode volumes, and both spontaneous-emission modification (the Purcell effect) and strong-coupling phenomena have been demonstrated. The use of photonic crystals and nanocavities to manipulate spontaneous emission will contribute to the evolution of a variety of applications, including illumination, display, optical communication, solar energy and even quantum-information systems.

The oxidation of alcohols to aldehydes with O₂ in place of stoichiometric oxygen donors is a crucial process for the synthesis of fine chemicals. However, the catalysts that have been identified so far are relatively inactive with primary alkyl alcohols. We showed that Au/Pd-TiO₂ catalysts give very high turnover frequencies (up to 270,000 turnovers per hour) for the oxidation of alcohols, including primary alkyl alcohols. The addition of Au to Pd nanocrystals improved the overall selectivity and, using scanning transmission electron microscopy combined with x-ray photoelectron spectroscopy, we showed that the Au-Pd nanocrystals were made up of a Au-rich core with a Pd-rich shell, indicating that the Au electronically influences the catalytic properties of Pd.

Substantial evidence shows that physical activity and fitness play a protective role in the development of stress related disorders. However, the beneficial effects of fitness for resilience to modern life stress are not fully understood. Potentially protective effects may be attributed to enhanced resilience via underlying psychosocial mechanisms such as self-efficacy expectations. This study investigated whether physical activity and fitness contribute to prospectively measured resilience and examined the mediating effect of general self-efficacy. 431 initially healthy adults participated in fitness assessments as part of a longitudinal-prospective study, designed to identify mechanisms of resilience. Self-efficacy and habitual activity were assessed in parallel to cardiorespiratory and muscular fitness, which were determined by a submaximal step-test, hand strength and standing long jump test. Resilience was indexed by stressor reactivity: mental health problems in relation to reported life events and daily hassles, monitored quarterly for nine months. Hierarchical linear regression models and bootstrapped mediation analyses were applied. We could show that muscular and self-perceived fitness were positively associated with stress resilience. Extending this finding, the muscular fitness–resilience relationship was partly mediated by self-efficacy expectations. In this context, self-efficacy expectations may act as one underlying psychological mechanism, with complementary benefits for the promotion of mental health. While physical activity and cardiorespiratory fitness did not predict resilience prospectively, we found muscular and self-perceived fitness to be significant prognostic parameters for stress resilience. Although there is still more need to identify specific fitness parameters in light of stress resilience, our study underscores the general relevance of fitness for stress-related disorders prevention.