The conduction pathway of potassium channels is water free under physiological conditions.

Ion conduction through potassium channels is a fundamental process of life. On the basis of crystallographic data, it was originally proposed that potassium ions and water molecules are transported through the selectivity filter in an alternating arrangement, suggesting a "water-mediated" knock-on mechanism. Later on, this view was challenged by results from molecular dynamics simulations that revealed a "direct" knock-on mechanism where ions are in direct contact. Using solid-state nuclear magnetic resonance techniques tailored to characterize the interaction between water molecules and the ion channel, we show here that the selectivity filter of a potassium channel is free of water under physiological conditions. Our results are fully consistent with the direct knock-on mechanism of ion conduction but contradict the previously proposed water-mediated knock-on mechanism

Zero kinetic energy-pulsed field ionization and resonance enhanced multiphoton ionization photoelectron spectroscopy: Ionization dynamics of Rydberg states in HBr

The results of rotationally resolved resonance enhanced multiphoton ionization photoelectron spectroscopy and zero kinetic energy‐pulsed field ionization studies on HBr via various rotational levels of the F^ 1Δ_2 and f^ 3Δ_2 Rydberg states are reported. These studies lead to an accurate determination of the lowest ionization threshold as 94 098.9±1 cm^(−1). Observed rotational and spin–orbit branching ratios are compared to the results of ab initio calculations. The differences between theory and experiment highlight the dominant role of rotational and spin–orbit interactions for the dynamic properties of the high‐n Rydberg states involved in the pulsed field ionization process

Sinuous breakdown in a flat plate boundary layer exposed to free-stream turbulence

In a flat plate boundary layer, perturbed with streaks, breakdown occurs due to a secondary instability acting on the streaks. An experimental study using a water channel with static turbulence grid, revealed the presence of a sinuous secondary instability mode in the bypass transition process. Five sinuous instabilities are investigated in detail in the horizontal plane. The streamwise length scale of the sinuous instability is around $40\delta^*_{300}$ and the spanwise scale equals around $\delta^*_{300}$. Four main features are found in the underlying streak configuration and developing streak-streak interactions. Firstly, all instabilities arise in a streak configuration where two low speed streaks are located at a small spanwise distance from each other. Patches of low speed fluid (forming a discontinuity in the streak pattern) are present in the high speed streaks surrounding the unstable low speed streak. As a consequence of the streak-streak interactions at the discontinuities vortices arise in a staggered configuration. Finally, the vortices develop into three-dimensional structures after which the flow falls apart into smaller three-dimensional flow regions

Stimulating job crafting behaviors of older workers:The influence of opportunity-enhancing human resource practices and psychological empowerment

Since job crafting behaviour is of profound importance for the retention of older workers, we examined how organizations can stimulate job crafting behaviour among older workers with opportunity-enhancing Human Resource (HR) practices. We introduced three job crafting behaviours: accommodative, utilization, and developmental job crafting. We hypothesized that opportunity-enhancing HR practices increase psychological empowerment among older workers and therefore their job crafting behaviour. We conducted a survey study with two waves among 125 Dutch older workers (65+) affiliated with a temporary employment agency aiming to employ older workers and found that changes in perceptions of opportunity-enhancing HR practices are positively related to changes in psychological empowerment and, in turn, to changes in utilization and developmental crafting behaviours. Unexpectedly, changes in psychological empowerment were not associated with changes in accommodative crafting and changes in opportunity-enhancing HR practices perceptions were not directly associated with changes in job crafting behaviour. With this study, we contribute to the literature on job crafting and human resource management by showing that opportunity-enhancing HR practices influence job crafting behaviour through psychological empowerment

Direct microwave measurement of Andreev-bound-state dynamics in a proximitized semiconducting nanowire

The modern understanding of the Josephson effect in mesosopic devices derives from the physics of Andreev bound states, fermionic modes that are localized in a superconducting weak link. Recently, Josephson junctions constructed using semiconducting nanowires have led to the realization of superconducting qubits with gate-tunable Josephson energies. We have used a microwave circuit QED architecture to detect Andreev bound states in such a gate-tunable junction based on an aluminum-proximitized InAs nanowire. We demonstrate coherent manipulation of these bound states, and track the bound-state fermion parity in real time. Individual parity-switching events due to non-equilibrium quasiparticles are observed with a characteristic timescale $T_\mathrm{parity} = 160\pm 10~\mathrm{\mu s}$. The $T_\mathrm{parity}$ of a topological nanowire junction sets a lower bound on the bandwidth required for control of Majorana bound states

Energy spectrum of the relativistic Dirac-Morse problem

We derive an elegant analytic formula for the energy spectrum of the relativistic Dirac-Morse problem, which has been solved recently. The new formula displays the properties of the spectrum more vividly.Comment: Replaced with a more potrable PDF versio

People with dementia playing casual games on a tablet

Objective: Preserving clients’ quality of life (QoL) has become increasingly important in dementia care. Engagement in pleasant and meaningful activities may influence this QoL. We studied people with dementia’s experiences and views of independent tablet games in a practice-based study, conducted at two day-care centres and five small-scale living facilities for people with dementia in the city of Rotterdam. Method: The participants were 54 clients (24 men, 30 women; mean age 83 years) who participated in a total of 177 game-playing sessions. Ten existing iPad games and three new game prototypes were evaluated. Written informed consent was obtained from the clients or the clients’ representatives prior to the study. Data collection included epidemiological and game playing characteristics. Observers took note of the specific game(s) offered, the clients’ mood and engagement, and the duration of game playing. Immediately after each participant finished playing,a short 4-question interview was conducted to discover their opinion on the game. The participants’ answers were recorded verbatim. Qualitative content analysis was used to explore their experiences and views of the games. Results: This study revealed positive experiences related to people’s need for achievement, self-esteem, sense of connection and belonging, identity, having something to do, and admiration for the game. Negative experiences included failure (low self-esteem), annoyance and a sense of insecurity. Conclusions: This study shows there is potential for people with dementia to play casual games on a tablet as a pleasant and meaningful activity. It is important, however that there is a match between the game, the touchscreen skills of the person with dementia, and their ambitions or interests. It is challenging to find the right game for the right person. An interactive tool to support the choice of the game that is most suitable and a database of dementia-friendly tablet games may support the use of these games by people with dementia, in health care organisations as well as at home

HCl and ClO in activated Arctic air; first retrieved vertical profiles from TELIS submillimetre limb spectra

The first profile retrieval results of the Terahertz and submillimeter Limb Sounder (TELIS) balloon instrument are presented. The spectra are recorded during a 13-h balloon flight on 24 January 2010 from Kiruna, Sweden. The TELIS instrument was mounted on the MIPAS-B2 gondola and shared this platform with the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) and the mini- Differential Optical Absorption Spectroscopy (mini-DOAS) instruments. The flight took place within the Arctic vortex at an altitude of ≈34 km in chlorine activated air, and both active (ClO) and inactive chlorine (HCl) were measured over an altitude range of respectively ≈16–32 km and ≈10– 32 km. In this altitude range, the increase of ClO concentration levels during sunrise has been recorded with a temporal resolution of one minute. During the daytime equilibrium, a maximum ClO level of 2.1±0.3 ppbv has been observed at an altitude of 23.5 km. This equilibrium profile is validated against the ClO profile by the satellite instrument Microwave Limb Sounder (MLS) aboard EOS Aura. HCl profiles have been determined from two different isotopes – H35Cl and H37Cl – and are also validated againstMLS. The precision of all profiles is well below 0.01 ppbv and the overall accuracy is therefore governed by systematic effects. The total uncertainty of these effects is estimated to be maximal 0.3 ppbv for ClO around its peak value at 23.5 km during the daytime equilibrium, and for HCl it ranges from 0.05 to 0.4 ppbv, depending on altitude. In both cases the main uncertainty stems from a largely unknown non-linear response in the detector

Observation of Andreev Reflection Enhanced Shot Noise

We have experimentally investigated the quasiparticle shot noise in NbN/MgO/NbN superconductor - insulator - superconductor tunnel junctions. The observed shot noise is significantly larger than theoretically expected. We attribute this to the occurrence of multiple Andreev reflection processes in pinholes present in the MgO barrier. This mechanism causes the current to flow in large charge quanta (Andreev clusters), with a voltage dependent average value of m = 1+ 2 Delta/eV times the electron charge. Because of this charge enhancement effect, the shot noise is increased by the factor m.Comment: 4 pages, 5 figures include