Understanding the transfer of spin angular momentum is essential in modern magnetism research. A model case is the generation of magnons in magnetic insulators by heating an adjacent metal film. ...Here, we reveal the initial steps of this spin Seebeck effect with <27 fs time resolution using terahertz spectroscopy on bilayers of ferrimagnetic yttrium iron garnet and platinum. Upon exciting the metal with an infrared laser pulse, a spin Seebeck current j
arises on the same ~100 fs time scale on which the metal electrons thermalize. This observation highlights that efficient spin transfer critically relies on carrier multiplication and is driven by conduction electrons scattering off the metal-insulator interface. Analytical modeling shows that the electrons' dynamics are almost instantaneously imprinted onto j
because their spins have a correlation time of only ~4 fs and deflect the ferrimagnetic moments without inertia. Applications in material characterization, interface probing, spin-noise spectroscopy and terahertz spin pumping emerge.
Determining the sample size of an experiment can be challenging, even more so when incorporating external information via a prior distribution. Such information is increasingly used to reduce the ...size of the control group in randomized clinical trials. Knowing the amount of prior information, expressed as an equivalent prior effective sample size (ESS), clearly facilitates trial designs. Various methods to obtain a prior's ESS have been proposed recently. They have been justified by the fact that they give the standard ESS for one‐parameter exponential families. However, despite being based on similar information‐based metrics, they may lead to surprisingly different ESS for nonconjugate settings, which complicates many designs with prior information. We show that current methods fail a basic predictive consistency criterion, which requires the expected posterior‐predictive ESS for a sample of size N to be the sum of the prior ESS and N. The expected local‐information‐ratio ESS is introduced and shown to be predictively consistent. It corrects the ESS of current methods, as shown for normally distributed data with a heavy‐tailed Student‐t prior and exponential data with a generalized Gamma prior. Finally, two applications are discussed: the prior ESS for the control group derived from historical data and the posterior ESS for hierarchical subgroup analyses.
The cobalt(I)-catalyzed cyclotrimerization of (un)symmetrical 1,4-disubstituted 1,3-butadiynes is presented. In the case of unsymmetrical 1,3-butadiynes, this reaction can generate eight ...1,2,4-substituted and four 1,3,5-substituted isomers. A single 1,2,4-substituted isomer was formed in excellent yields (up to 99%) and exclusive regioselectivities (>99:1) when symmetrical or a 1,3-butadiyne with an aryl or alkyl substituent and a trimethylsilyl group were applied. A large number of products accepting a wide variety of functional groups were synthesized.
Indium tribromide catalysed the transfer hydrogenation from dihydroaromatic compounds, such as the commercially available γ‐terpinene, to enones, which resulted in the cyclisation to trisubstituted ...furan derivatives. The reaction was initiated by a Michael addition of a hydride nucleophile to the enone subunit followed by a Lewis‐acid‐assisted cyclisation and the formation of a furan–indium intermediate and a Wheland intermediate derived from the dihydroaromatic starting material. The product was formed by protonation from the Wheland complex and replaced the indium tribromide substituent. In addition, a site‐specific deuterium labelling of the dihydroaromatic HD surrogates resulted in site specific labelling of the products and gave useful insights into the reaction mechanism by H–D scrambling.
InBr3 is used as functional‐group‐tolerant catalyst for the transfer hydrogenation from γ‐terpinene as H2 surrogate to initiate the cyclisation of 2‐alkynyl‐substituted enones to trisubstituted furans in good yields. Design of Experiments was used to optimise the reaction conditions with a few experiments to almost quantitative yields and deuterium‐labelling experiments gave valuable mechanistic insights.
Randomized controlled trials are the gold standard to investigate efficacy and safety of new treatments. In certain settings, however, randomizing patients to control may be difficult for ethical or ...feasibility reasons. Borrowing strength using relevant individual patient data on control from external trials or real‐world data (RWD) sources may then allow us to reduce, or even eliminate, the concurrent control group. Naive direct use of external control data is not valid due to differences in patient characteristics and other confounding factors. Instead, we suggest the rigorous application of meta‐analytic and propensity score methods to use external controls in a principled way. We illustrate these methods with two case studies: (i) a single‐arm trial in a rare cancer disease, using propensity score matching to construct an external control from RWD; (ii) a randomized trial in children with multiple sclerosis, borrowing strength from past trials using a Bayesian meta‐analytic approach.
The Alder-ene reaction of trialkylsilyl-substituted 1,3-butadiynes with terminal alkenes was investigated utilizing a cobalt-based catalyst, and the results were compared with Alder-ene rections ...catalyzed by the CpRu(H3CCN)3PF6 catalyst. Obviously, the two catalysts gave complementary results of yn-dienes differing in the site where the new carbon–carbon bond was formed. Of particular interest are observations concerning the double bond migration within the alkene component. While simple alkenes gave exclusively the E-configuration, the application of 3-buten-1-ol resulted in the corresponding Z-double bond, indicating that the hydroxyl group acts as donor coordinating to the cobalt center and thereby altering the reaction pathway.
A diastereoselective hydroalkynylation of terminal alkynes to form the head‐to‐head dimerization products by two different cobalt‐phosphine catalyst system is reported. The use of the bidentate ...ligand dppp and additional triphenylphosphine led to the selective formation of the (E)‐1,3‐enynes (E:Z>99:1) in good to excellent yields, while the tridentate ligand TriPhos led to the corresponding (Z)‐1,3‐enynes in moderate to good yields with excellent stereoselectivities (up to E:Z=1:99). Both pre‐catalysts are easy to handle, because of their stability under atmospheric conditions. The optimized reaction conditions were identified by the Design of Experiments (DoE) approach, which has not been used before in cobalt‐catalysed reaction optimisation. DoE decreased the number of required reactions to a minimum.
Cobalt catalysis at a crossroad: The choice of the ligands in a cobalt‐catalysed hydroalkynylation of terminal alkynes is decisive to form the dimerization products in a diastereoselective fashion. The (E)‐1,3‐enynes are formed in good to excellent yields and outstanding selectivities (E:Z>99:1), while the corresponding (Z)‐1,3‐enynes were isolated in moderate to good yields with excellent stereoselectivities (up to E:Z=1:99).
Free electron lasers offer unique properties to study matter in states far from equilibrium as they combine short pulses with a large range of photon energies. In particular, the possibility to ...excite core states drives new relaxation pathways that, in turn, also change the properties of the optically and chemically active electrons. Here, we present a theoretical model for the dynamics of the nonequilibrium occupation of the different energy bands in solid gold driven by exciting deep core states. The resulting optical response is in excellent agreement with recent measurements and, combined with our model, provides a quantitative benchmark for the description of electron-phonon coupling in strongly driven gold. Focusing on sub-picosecond time scales, we find essential differences between the dynamics induced by XUV and visible light.
Today, researchers, practitioners, and physicians measure the concentration of lactate during a graded exercise test to determine thresholds related to the maximal lactate steady state (maxLass) as a ...sensitive measure of endurance capacity. In the 1970s and 1980s, a group of Cologne-based researchers around Wildor Hollmann, Alois Mader, and Hermann Heck developed the methodology for systematic lactate testing and introduced a 4 mmol
.
L
−1
lactate threshold. Later, they also developed the concept of the maxLass, and Mader designed a sophisticated mathematical model of human energy metabolism during exercise. Mader`s model simulates metabolic responses to exercise based on individual variables such as maximum oxygen uptake (
V
˙
O
2max
) and the maximal rate of lactate formation (ν
La.max
). Mader’s model predicts that the ν
La.max
reduces the power at the anaerobic threshold and endurance performance but that a high ν
La.max
is required for events with high power outputs in elite athletes. Mader’s model also assumed before the millennium that the rate of fat oxidation is explained by the difference between glycolytic pyruvate synthesis and the actual rate of pyruvate oxidation which is consistent with current opinion. Mader’s model also simulated the
V
˙
O
2max
slow component in the mid-1980s. Unfortunately, several landmark studies by the Cologne group were only published in German, and as a result, contributions by the Cologne group are under-appreciated in the English-speaking world. This narrative review aims to introduce key contributions of the Cologne group to human metabolism research especially for readers who do not speak German.
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