SQUATS PERFORMED ON AN UNSTABLE SURFACE ELICIT HIGHER TRANSVERSAL FORCE OUTPUT COMPARED TO MORE STABLE SQUATS

Instability resistance training (RT) or exercising within an unstable environment is a popular training modality and frequently used in training, rehabilitation and prevention settings. Yet, due to the reported reduced force output during exercising within unstable condition, instability RT is said to lack the necessary overload to induce meaningful effects. However, empirical evidence of interventions suggests otherwise. The aim of this study was to systematically analyse instability RT vs. stable RT and discuss potential mechanisms. Therefore, we analysed squats within unstable and stable environments and calculated transversal and vertical forces. Greater transversal plane ground reaction forces were observed while performing squats on the unstable surface (p = .013; d = 1.88, CI-95% [0.33, 3.39]). In contrast, vertical force output remained similar for both conditions (p = .764; d = 0.14, CI-95% [-0.77, 1.02])

Phonons and related properties of extended systems from density-functional perturbation theory

This article reviews the current status of lattice-dynamical calculations in crystals, using density-functional perturbation theory, with emphasis on the plane-wave pseudo-potential method. Several specialized topics are treated, including the implementation for metals, the calculation of the response to macroscopic electric fields and their relevance to long wave-length vibrations in polar materials, the response to strain deformations, and higher-order responses. The success of this methodology is demonstrated with a number of applications existing in the literature.Comment: 52 pages, 14 figures, submitted to Review of Modern Physic

The dynamics of Early Celtic consumption practices: a case study of the pottery from the Heuneburg

The Early Celtic site of the Heuneburg (Baden-Wuerttemberg, Germany) has long been understood as a hallmark of early urbanization in Central Europe. The rich collection of Mediterranean imports recovered from the settlement, the elite burials in its surroundings and the Mediterranean-inspired mudbrick fortification wall further point to the importance of intercultural connections with the Mediterranean as a crucial factor in the transformation of Early Iron Age societies. We describe a new facet of this process by studying the transformation of consumption practices, especially drinking habits, brought about by intercultural encounters from the late 7th to the 5th century BC through the analysis of organic remains in 133 ceramic vessels found at the Heuneburg using Organic Residue Analysis (ORA). During the Ha D1 phase, fermented beverages, including Mediterranean grape wine, were identified in and appear to have been consumed from local handmade ceramics. The latter were recovered from different status-related contexts within the Heuneburg, suggesting an early and well-established trade/exchange system of this Mediterranean product. This contrasts with the results obtained for the drinking and serving vessels from the Ha D3 phase that were studied. The consumption of fermented beverages (wine and especially bacteriofermented products) appears to have been concentrated on the plateau. The ORA analyses presented here seem to indicate that during this time, grape wine was consumed primarily from imported vessels, and more rarely from local prestigious fine wheel-made vessels. In addition to imported wine, we demonstrate the consumption of a wide variety of foodstuffs, such as animal fats (especially dairy products), millet, plant oils and waxy plants, fruit and beehive products as well as one or several other fermented beverage(s) that were probably locally produced. Through this diachronic study of vessel function from different intra-site contexts, we inform on changing and status-related practices of food processing and consumption

Refining and regaining skills in fixation/diversification stage performers: The Five-A Model

Technical change is one of many factors underpinning success in elite, fixation/diversification stage performers. Surprisingly, however, there is a dearth of research pertaining to this process or the most efficacious methods used to bring about such a change. In this paper we highlight the emergent processes, yet also the lack in mechanistic comprehension surrounding technical change, addressing issues within the motor control, sport psychology, coaching and choking literature. More importantly, we seek an understanding of how these changes can be made more secure to competitive pressure, and how this can be embedded within the process of technical change. Following this review, we propose The Five-A Model based on successful coaching techniques, psychosocial concomitants, the avoidance of choking and principles of effective behaviour change. Specific mechanisms for each stage are discussed, with a focus on the use of holistic rhythm-based cues as a possible way of internalising changes. Finally, we suggest the need for further research to examine these five stages, to aid a more comprehensive construction of the content and delivery of such a programme within the applied setting

What autocorrelation tells us about motor variability: Insights from dart throwing

In sports such as golf and darts it is important that one can produce ballistic movements of an object towards a goal location with as little variability as possible. A factor that influences this variability is the extent to which motor planning is updated from movement to movement based on observed errors. Previous work has shown that for reaching movements, our motor system uses the learning rate (the proportion of an error that is corrected for in the planning of the next movement) that is optimal for minimizing the endpoint variability. Here we examined whether the learning rate is hard-wired and therefore automatically optimal, or whether it is optimized through experience. We compared the performance of experienced dart players and beginners in a dart task. A hallmark of the optimal learning rate is that the lag-1 autocorrelation of movement endpoints is zero. We found that the lag-1 autocorrelation of experienced dart players was near zero, implying a near-optimal learning rate, whereas it was negative for beginners, suggesting a larger than optimal learning rate. We conclude that learning rates for trial-by-trial motor learning are optimized through experience. This study also highlights the usefulness of the lag-1 autocorrelation as an index of performance in studying motor-skill learning

Miniband-related 1.4–1.8 μm luminescence of Ge/Si quantum dot superlattices

The luminescence properties of highly strained, Sb-doped Ge/Si multi-layer heterostructures with incorporated Ge quantum dots (QDs) are studied. Calculations of the electronic band structure and luminescence measurements prove the existence of an electron miniband within the columns of the QDs. Miniband formation results in a conversion of the indirect to a quasi-direct excitons takes place. The optical transitions between electron states within the miniband and hole states within QDs are responsible for an intense luminescence in the 1.4–1.8 µm range, which is maintained up to room temperature. At 300 K, a light emitting diode based on such Ge/Si QD superlattices demonstrates an external quantum efficiency of 0.04% at a wavelength of 1.55 µm

Difficult tracheal intubation in neonates and infants. NEonate and Children audiT of Anaesthesia pRactice IN Europe (NECTARINE): a prospective European multicentre observational study

Background: Neonates and infants are susceptible to hypoxaemia in the perioperative period. The aim of this study was to analyse interventions related to anaesthesia tracheal intubations in this European cohort and identify their clinical consequences. Methods: We performed a secondary analysis of tracheal intubations of the European multicentre observational trial (NEonate and Children audiT of Anaesthesia pRactice IN Europe [NECTARINE]) in neonates and small infants with difficult tracheal intubation. The primary endpoint was the incidence of difficult intubation and the related complications. The secondary endpoints were the risk factors for severe hypoxaemia attributed to difficult airway management, and 30 and 90 day outcomes. Results: Tracheal intubation was planned in 4683 procedures. Difficult tracheal intubation, defined as two failed attempts of direct laryngoscopy, occurred in 266 children (271 procedures) with an incidence (95% confidence interval [CI]) of 5.8% (95% CI, 5.1e6.5). Bradycardia occurred in 8% of the cases with difficult intubation, whereas a significant decrease in oxygen saturation (SpO2<90% for 60 s) was reported in 40%. No associated risk factors could be identified among comorbidities, surgical, or anaesthesia management. Using propensity scoring to adjust for confounders, difficult anaesthesia tracheal intubation did not lead to an increase in 30 and 90 day morbidity or mortality. Conclusions: The results of the present study demonstrate a high incidence of difficult tracheal intubation in children less than 60 weeks post-conceptual age commonly resulting in severe hypoxaemia. Reassuringly, the morbidity and mortality at 30 and 90 days was not increased by the occurrence of a difficult intubation event. Clinical trial registration: NCT02350348