Abstract. Using the method of unitary transformation in combination with chiral effective field theory we derive the two-pion exchange contributions to the two-nucleon electromagnetic current. A formal definition of the current operator in this scheme and the power counting is presented. We discuss the implications of additional unitary transformations that have to be present to ensure the renormalizability of the one-pion exchange current. Further, we give explicit and compact results for the current in coordinate-space.

We derive the leading one-loop contribution to the one-pion exchange and short-range two-nucleon electromagnetic current operator in the framework of chiral effective field theory. The derivation is carried out using the method of unitary transformation. Explicit results for the current and charge densities are given in momentum and coordinate space.

Sleep duration is truncated during long-haul international travel with a 4-h time-zone delay and after night matches in elite footballers. However, this lost sleep appeared to have a limited effect on perceptual recovery, which may be explained by a westbound flight and a relatively small change in time zones, in addition to the significant increase in sleep duration on the night of arrival after the long-haul flight.

Recovery is essential for high athletic performance, and therefore especially sleep has been identified as a crucial source for physical and psychological well-being. However, due to early-morning trainings, which are general practice in many sports, athletes are likely to experience sleep restrictions. Therefore, this study investigated the sleep-wake patterns of 55 junior national rowers (17.7 ± 0.6 years) via sleep logs and actigraphy during a four-week training camp. Recovery and stress ratings were obtained every morning with the Short Recovery and Stress Scale on a 7-point Likert-type scale ranging from 0 (does not apply at all) to 6 (fully applies). The first training session was scheduled for 6:30 h every day. With two to four training sessions per day, the training load was considerably increased from athletes' home training. Objective sleep measures (n = 14) revealed less total sleep time (TST) in the first two weeks (409.6 ± 19.1 and 416.0 ± 16.3 min), while training volume and intensity were higher. In the second half of the camp, less training sessions were implemented, more afternoons were training free and TSTs were longer (436.3 ± 15.8 and 456.9 ± 25.7 min). A single occasion of 1.5-h delayed bedtime and usual early morning training (6:30 h) resulted in reduced ratings of Overall Recovery (OR) (M = 3.3 ± 1.3) and greater Negative Emotional State (NES) (M = 1.3 ± 1.2, p < .05), which returned to baseline on the next day. Following an extended night due to the only training-free day, sleep-offset times were shifted from ~5:30 to ~8:00 h, and each recovery and stress score improved (p < .01). Moreover, subjective ratings of the first six days were summarised as a baseline score to generate reference data as well as to explore the association between sleep and recovery. Intercorrelations of these sleep parameters emphasised the relationship between restful sleep and falling asleep quickly (r = .34, p < .05) as well as few awakenings (r = .35, p < .05). Overall, the findings highlight the impact of sleep on subjective recovery measures in the setting of a training camp. Providing the opportunity of extended sleep (and a day off) seems the most simple and effective strategy to enhance recovery and stress-related ratings.

The recently derived long-range two-pion exchange (TPE) contributions to the nuclear current operator which appear at next-to-leading order (NLO) of the chiral expansion are used to describe electromagnetic processes. We study their role in the photodisintegration of 2 H and 3 He and compare our predictions with experimental data. The bound and scattering states are calculated using five different parametrizations of the chiral next-to-next-to-leading order (N 2 LO) nucleon-nucleon (NN) potential which allows us to estimate the theoretical uncertainty at a given order in the chiral expansion. For some observables the results are very close to the predictions based on the AV18 NN potential and the current operator (partly) consistent with this force. In the most cases, the addition of long-range TPE currents improved the description of the experimental data.

The body of research that reports the relevance of sleep in high-performance sports is growing steadily. While the identification of sleep cycles and diagnosis of sleep disorders is limited to lab-based assessment via polysomnography, the development of activity-based devices estimating sleep patterns provides greater insight into the sleep behaviour of athletes in ecological settings. Overall, small sleep quantity and/or poor quality appears to exist in many athletic populations, though this may be related to training and competition context. Typical sleep-affecting factors are the scheduling of training sessions and competitions as well as impaired sleep-onset as a result of increased arousal prior to competition or due to the use of electronic devices before bedtime. Further challenges are travel demands which may be accompanied by jet-lag symptoms and disruption of sleep habits. Promotion of sleep may be approached via behavioural strategies, such as sleep hygiene, extending night-time sleep or daytime napping. Pharmacological interventions should be limited to clinically-induced treatments as evidence among healthy and athletic populations is lacking. To optimise and manage sleep in athletes, it is recommended to implement routine sleep monitoring on an individual basis.

We calculate the magnetic form factor of the deuteron up to O(eP 4 ) in the chiral EFT expansion of the electromagnetic current operator. The two LECs which enter the two-body part of the isoscalar NN three-current operator are fit to experimental data, and the resulting values are of natural size. The O(eP 4 ) description of GM agrees with data for momentum transfers Q 2 < 0. Introduction: In the past two decades chiral effective field theory (χEFT) was fruitfully applied to few-nucleon dynamics (see Refs. [1, 2] for recent reviews). Twonucleon potentials at next-to-next-to-next-to-leading order (N 3 LO) in the chiral expansion were developed [3, 4] which accurately describe low-energy scattering data and the static properties of the deuteron. Higher-order corrections to the three-nucleon force are presently under investigation, see e.g. [10], although discussions regarding non-perturbative renormalization of the Schrödinger equation and implications for the χEFT power counting continue, see [5][6][7][8][9] for samples of different views. In parallel to these developments in the strong sector, much effort has been devoted to pionic and electroweak reactions in few-nucleon systems, see [11][12][13] for recent examples.

The concept of recovery strategies includes various ways to achieve a state of well-being, prevent underrecovery syndromes from occurring and re-establish pre-performance states. A systematic application of individualised relaxation techniques is one of those. Following a counterbalanced cross-over design, 27 sport science students (age 25.22 ± 1.08 years; sports participation 8.08 ± 3.92 h/week) were randomly assigned to series of progressive muscle relaxation, systematic breathing, power nap, yoga, and a control condition. Once a week, over the course of five weeks, their repeated sprint ability was tested. Tests (6 sprints of 4 s each with 20 s breaks between them) were executed on a non-motorised treadmill twice during that day intermitted by 25 min breaks. RM-ANOVA revealed significant interaction effects between the relaxation conditions and the two sprint sessions with regard to average maximum speed over all six sprints, F(4,96) = 4.06, P = 0.004, [Formula: see text] = 0.15. Post-hoc tests indicated that after systematic breathing interventions, F(1,24) = 5.02, P = 0.033, [Formula: see text] = 0.18, participants performed significantly better compared to control sessions. As the focus of this study lied on basic mechanisms of relaxation techniques in sports, this randomised controlled trial provides us with distinct knowledge on their effects, i.e., systematic breathing led to better performances, and therefore, seems to be a suited relaxation method during high-intensity training.