Electrical conduction in single crystals of alumina

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Three terminal laser structure for high-speed modulation using dynamic carrier heating

A three-terminal laser structure is proposed as a means to achieve laser modulation using dynamic carrier heating. The injection of hot electrons, with energy tuned by variable joule heating over a high electric field region, is used to govern the carrier temperature in the active layer of a laser, while a separate heterojunction controls the injection rate. Simulations show the possibility of generating good-shaped picosecond optical pulses by modulating the voltage that controls the heating electric field

Field-based tests for the assessment of physical fitness in children and adolescents practicing sport: A systematic review within the ESA program

High levels of physical fitness (PF) can positively affect both health and cognitive function, thus monitoring its levels in youth can help increase health and quality of life in adult populations later on. This systematic review aims to identify PF field-based tests used in young European populations practicing sport to find tools that are adequate for the considered target involving a new battery within the Enriched Sport Activities (ESA) project. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was followed. In the 83 identified articles, the main tests used were: vertical/horizontal jumps (for muscular strength/power); push-ups, running at maximum effort, sit-ups (for muscular strength/endurance); multistage non-intermittent and intermittent tests (for aerobic endurance); sit and reach (for flexibility); sprinting and agility T-tests (for speed and agility, respectively); 10 x 5 m shuttle run (SR) (for both speed and agility). Few studies assessed coordination, reaction time, power, and balance. Although the selected tests are widely used and validated, they do not determine all PF aspects and do not reflect sport-specific features. A final decision was made for the inclusion of the following tests: standing broad jump, seated medicine ball throw, 20 m SR test, 30 m sprint, Illinois test, and a new test, i.e., the crunning test, to assess different skill-related components at once. The use of this combination of tests allows for the assessment of all PF components and can help planning eective training programs and cultivate sporting talent

Modeling of the transient interstitial diffusion of implanted atoms during low-temperature annealing of silicon substrates

It has been shown that many of the phenomena related to the formation of "tails" in the low-concentration region of ion-implanted impurity distribution are due to the anomalous diffusion of nonequilibrium impurity interstitials. These phenomena include boron implantation in preamorphized silicon, a "hot" implantation of indium ions, annealing of ion-implanted layers et cetera. In particular, to verify this microscopic mechanism, a simulation of boron redistribution during low-temperature annealing of ion-implanted layers has been carried out under different conditions of transient enhanced diffusion suppression. Due to the good agreement with the experimental data, the values of the average migration length of nonequilibrium impurity interstitials have been obtained. It has been shown that for boron implanted into a silicon layer preamorphized by germanium ions the average migration length of impurity interstitials at the annealing temperature of 800 Celsius degrees be reduced from 11 nm to approximately 6 nm due to additional implantation of nitrogen. The further shortening of the average migration length is observed if the processing temperature is reduced to 750 Celsius degrees. It is also found that for implantation of BF2 ions into silicon crystal, the value of the average migration length of boron interstitials is equal to 7.2 nm for thermal treatment at a temperature of 800 Celsius degrees.Comment: 10 pages, 6 figures, RevTe

Cognitive and motivational monitoring during enriched sport activities in a sample of children living in Europe. The ESA program

Enriched Sport Activities (ESA) Program is an Evidence-based Practice Exercise Program cofounded by the Erasmus + Programme of the European Union (Key action: Sport-579661-EPP-1-2016-2-IT-SPO-SCP). It aims to enhance social inclusion, equal opportunities and psycho-physical wellbeing in children with typical development and special needs. This aim will be pursued through two ways: (1) Children and preadolescents’ participation in Enriched Sport Activities (ESA) Program; (2) Parents’ involvement and education on cognitive, motivational and social benefits of Physical Activities (PA) in their children. Recent research showed that high-level cognitive processes, such as inhibition, shifting, working memory and planning, can be improved by aerobic exercise programs following both single bouts of exercise and longer trainings from moderate to vigorous intensity [1]. Nevertheless, in the developmental age, structured sport activities, such as martial arts, basketball, soccer, rowing and dancing, act by delivering both physical and psychological benefits. The former involve physical fitness such as cardiorespiratory fitness, muscular strength, muscular endurance, flexibility and motor skills such as coordination, whilst the latter concern enjoyment, self-confidence and self-esteem, a sense of belonging and social support [2–4]. The effectiveness of PMA (Programma Motorio Arricchito), a structured motor program on coordination and executive functioning in kindergarten children, has been demonstrated [5]

The chemistry and structure of lanthanide phosphates

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Solid-state synthesis and X-ray diffraction studies of Na2S

Na2S was synthesized by a new solid-gas reaction of Na2CO3 with a sulfidizing gas mixture and a solid-solid reaction of carbon with Na2SO4. The reaction products were analyzed by X-ray powder diffraction and IR methods. Two new crystal modifications of Na2S were identified in addition to the previously reported antifluorite structure. They were designated as cubic Form II and orthorhombic Form III. The approximate unit cell dimensions were found to be a = 11.29 Å for the cubic form and a = 15.94, b = 16.00, and c = 16.18 Å for the orthorhombic form