Terahertz Néel spin-orbit torques drive nonlinear magnon dynamics in antiferromagnetic Mn2Au.

Antiferromagnets have large potential for ultrafast coherent switching of magnetic order with minimum heat dissipation. In materials such as Mn2Au and CuMnAs, electric rather than magnetic fields may control antiferromagnetic order by Néel spin-orbit torques (NSOTs). However, these torques have not yet been observed on ultrafast time scales. Here, we excite Mn2Au thin films with phase-locked single-cycle terahertz electromagnetic pulses and monitor the spin response with femtosecond magneto-optic probes. We observe signals whose symmetry, dynamics, terahertz-field scaling and dependence on sample structure are fully consistent with a uniform in-plane antiferromagnetic magnon driven by field-like terahertz NSOTs with a torkance of (150 ± 50) cm2 A-1 s-1. At incident terahertz electric fields above 500 kV cm-1, we find pronounced nonlinear dynamics with massive Néel-vector deflections by as much as 30°. Our data are in excellent agreement with a micromagnetic model. It indicates that fully coherent Néel-vector switching by 90° within 1 ps is within close reach.

Antiferromagnetic half-skyrmions electrically generated and controlled at room temperature.

Topologically protected magnetic textures are promising candidates for information carriers in future memory devices, as they can be efficiently propelled at very high velocities using current-induced spin torques. These textures-nanoscale whirls in the magnetic order-include skyrmions, half-skyrmions (merons) and their antiparticles. Antiferromagnets have been shown to host versions of these textures that have high potential for terahertz dynamics, deflection-free motion and improved size scaling due to the absence of stray field. Here we show that topological spin textures, merons and antimerons, can be generated at room temperature and reversibly moved using electrical pulses in thin-film CuMnAs, a semimetallic antiferromagnet that is a testbed system for spintronic applications. The merons and antimerons are localized on 180° domain walls, and move in the direction of the current pulses. The electrical generation and manipulation of antiferromagnetic merons is a crucial step towards realizing the full potential of antiferromagnetic thin films as active components in high-density, high-speed magnetic memory devices.

Current-driven writing process in antiferromagnetic Mn2Au for memory applications.

Current pulse driven Néel vector rotation in metallic antiferromagnets is one of the most promising concepts in antiferromagnetic spintronics. We show microscopically that the Néel vector of epitaxial thin films of the prototypical compound Mn2Au can be reoriented reversibly in the complete area of cross shaped device structures using single current pulses. The resulting domain pattern with aligned staggered magnetization is long term stable enabling memory applications. We achieve this switching with low heating of ≈20 K, which is promising regarding fast and efficient devices without the need for thermal activation. Current polarity dependent reversible domain wall motion demonstrates a Néel spin-orbit torque acting on the domain walls.

[Prioritization of intensive medical treatment places - Concept proposal]. / Priorisierung intensivmedizinischer Behandlungsplätze ­ Konzeptvorschlag.

In the situation of a shortage of ventilation beds, ethically justifiable, transparent and comprehensible decisions must be made. This concept proposes that all patients are first intubated depending on necessity and then assessed by a triage team afterwards. In this situation newly admitted COVID patients compete with newly admitted Non-COVID patients as well as patients already treated in intensive care units for a ventilator. The combination of short-term and long-term prognoses should enable the interprofessional triage team to make comprehensible decisions. The aim of the prioritization concept is to save as many human lives as possible and to relieve the treatment team of the difficult decision on prioritization.

Learned predictiveness effects following single-cue training in humans.

The results of several recent studies of human associative learning indicate that people will learn more rapidly about cues that have previously been experienced as predictive of events of significance, as compared with cues previously experienced as nonpredictive. Notably, however, these experiments have typically established this prior predictiveness by means of pretraining with multiple, simultaneously presented cues, some of which are more predictive than others. The present experiments instead investigated the influence of prior predictiveness on future learning when this predictiveness was established via pretraining with individual cues, each of which was the best available predictor of the outcome with which it was paired. Results indicate that, following this pretraining, human participants again show better learning about previously predictive cues than about previously nonpredictive cues.

Impairing and monitoring glucose catabolite repression in L-carnitine biosynthesis.

Signal transduction pathways are usually avoided when optimizing a biotransformation process because they require complex mathematical formulations. The aim of this work was to use a Systems Biology approach to optimize and monitor the biotransformation of L-carnitine using signal transduction pathways. To this end, a dynamic model was constructed, integrating the metabolic pathways of L-carnitine biosynthesis as well as the expression of this metabolism by means of its regulation by transcription factors such as cAMP-CRP and CaiF. The model was validated using different C-sources as well as different reactor feeding approaches. A linear relationship between the external cellular cAMP and the L-carnitine production levels was predicted before being experimentally confirmed in several scenarios. Moreover, results of the model simulations and subsequent experimental findings demonstrated that the addition of exogenous cAMP was able to restore the L-carnitine production when glucose was used as C-source. Additionally, a way to monitor the L-carnitine biosynthesis by using the level of cAMP as a marker of the biotransformation state was in silico and experimentally demonstrated.

[Therapy motivation of young prisoners]. / Therapiemotivation junger Strafgefangener.

OBJECTIVES: Therapy adherence was examined within a sample of 145 imprisoned male juveniles with regard to factors of influence, structure and predictability. METHODS: Predictors included biographic data, expectations with regard to therapy, personality traits (measured with the FPI-R) and psychological impairment (investigated by means of the Symptom Checklist). Therapy adherence as a criterion can be divided into the following dimensions: affliction, dissatisfaction, requests for change and help, and expectations of success. RESULTS: Within the sample a clear impairment of biographical and psychological data, as well as of personality traits was found. Values were average for expectations regarding therapy and therapy adherence, while two thirds of the sample were willing to undergo treatment during imprisonment. CONCLUSIONS: Therapy adherence proved to be a one-dimensional construct, best predicted by emotional instability, followed by the symptom score, expectations regarding therapy and inhibition. Dividing the entire sample into subgroups, significant differences were found mainly for psychological test data and less so for the construct of therapy adherence.

Tests of the ratio rule in categorization.

Many theories of learning and memory (e.g., connectionist, associative, rational, exemplar based) produce psychological magnitude terms as output (i.e., numbers representing the momentary level of some subjective property). Many theories assume that these numbers may be translated into choice probabilities via the ratio rule, also known as the choice axiom (Luce, 1959) or the constant-ratio rule (Clarke, 1957). We present two categorization experiments employing artificial, visual, prototype-structured stimuli constructed from 12 symbols positioned on a grid. The ratio rule is shown to be incorrect for these experiments, given the assumption that the magnitude terms for each category are univariate functions of the number of category-appropriate symbols contained in the presented stimulus. A connectionist winner-take-all model of categorical decision (Wills & McLaren, 1997) is shown to account for our data given the same assumption. The central feature underlying the success of this model is the assumption that categorical decisions are based on a Thurstonian choice process (Thurstone, 1927, Case V) whose noise distribution is not double exponential in form.

Expression of mRNAs for type-I collagen, bone sialoprotein, osteocalcin, and osteopontin at different stages of osteoblastic differentiation and their regulation by 1,25 dihydroxyvitamin D3.

We have used in situ hybridization to evaluate the effects of 1,25 dihydroxyvitamin D3 (1,25 (OH)2 D3) on the expression of mRNA for bone-matrix proteins and to determine whether mature osteoblasts respond differently to 1,25 (OH)2 D3 than younger, newly differentiated osteoblasts. Rat calvaria cells were cultured for 7, 12, 15, and 19 days to obtain a range of nodules from very young to very mature. At each time point, some cultures were treated with 10 nM 1,25 (OH)2 D3 for 24 h prior to fixation. In control cultures, type-I collagen mRNA was detectable in osteoblastic cells in very young nodules and increased with increasing maturity of the nodules and the osteoblasts lining them. The bone sialoprotein mRNA signal was weak in young osteoblasts, increased in older osteoblasts, and decreased in mature osteoblasts. Weak osteocalcin and osteopontin signals were seen only in osteoblasts of intermediate and mature nodules. 1,25 (OH)2 D3 treatment markedly upregulated osteocalcin and osteopontin mRNAs and downregulated mRNA levels of bone sialoprotein and, to a lesser extent, type-I collagen in both young and mature osteoblasts. However, a marked diversity of signal levels for bone sialoprotein, osteocalcin, and osteopontin existed between neighboring mature osteoblasts, particularly after 1,25 (OH)2 D3 treatment, which may therefore selectively affect mature osteoblasts, depending on their differentiation status or functional stage of activity.

Influence of feeding hay on the alopecia of breeding guinea pigs.

Animals with partial alopecia were seen frequently in a breeding colony of guinea pigs. No pathologic aetiology could be determined. An influence of nutrition on the density of the hair coat was considered. Breeding groups were fed one of the commercial guinea pig diets of differing composition, with or without the addition of hay. Observation occurred over a period of months and the quality of the hair coat was evaluated periodically using a semi-quantitative scoring system. More extensive and more frequent fur defects were found is guinea pigs receiving a breeding diet with a high content of crude protein (23%) and a low level of crude fibre (12%), offered hay only restrictively compared with animals receiving a diet with a lower content of crude protein (15.5%) and a higher level of crude fibre (19.5%), offered the same amount of hay. The amount of hay offered is of paramount importance. Animals fed only the diet with the higher level of crude fibre (19.5%), according to the manufacturer's instructions as a complete food, without the addition of hay, showed a less dense hair coat within 4 weeks. In our colony a group of five breeding animals and their young required 200 g of hay daily in order to improve their hair coat quality to normal. Conversely, animals receiving less hay had progressively deteriorating hair coat density. Not only the amount of hay offered, but also the accessibility for all animals plays a role in preventing alopecia in guinea pigs. In larger cages (twice the usual ground surface area) fur defects were seen when the same amount of hay (200 g) was offered in only one central area, rather than spread out evenly throughout the cage. Hair loss was observed to be the result of trichophagia between adult animals kept in the same cage. The need for crude fibre of breeding animals does not appear to be completely met by pellets rich in fibre segments.

Changes in expression of alpha 1 type 1 collagen and osteocalcin mRNA in osteoblasts and odontoblasts at different stages of maturity as shown by in situ hybridization.

We investigated whether the expressed phenotype of osteoblasts and odontoblasts is changing with increasing maturity of the cells. Thus we determined, using in situ hybridization techniques, whether the expression of mRNA's for osteocalcin and the alpha 1 type 1 collagen chain was different in newly developed and more mature cuboidal osteoblasts of the primary and secondary spongiosa of radii of 8 day old rats, in mature cuboidal and older flat osteoblasts in the metatarsals of pig embryos, and in apical and coronal odontoblasts of the developing unerupted molars of pig embryos. The results indicate that newly differentiated osteoblasts in the primary spongiosa of the 8 day rat radius contained approximately the same amount of type 1 collagen message as more mature osteoblasts in the secondary spongiosa. Osteocalcin mRNA, on the other hand, was undetectable in the newly differentiated osteoblasts but clearly detectable in the mature osteoblasts of the secondary spongiosa. When we compared expression of osteocalcin and collagen type 1 mRNA in mature cuboidal and older flat osteoblasts, we found that the amount of osteocalcin mRNA relative to collagen type 1 mRNA was higher in flat osteoblasts than in cuboidal osteoblasts. In odontoblasts, however, the steady state level of collagen type 1 mRNA was higher in the older coronal odontoblasts, and the level of osteocalcin message lower, when compared to the younger apical odontoblasts. The results indicate that relative levels of osteocalcin and collagen mRNA in osteoblasts and odontoblasts vary depending on the stage in their secretory lifetime. This heterogeneity of the osteoblast and odontoblast population suggests that the composition of the matrix produced by these cells also differs.

Localization of bone sialoprotein (BSP) expression to sites of mineralized tissue formation in fetal rat tissues by in situ hybridization.

Bone sialoprotein (BSP) is a major protein in the mineralized matrix of bone and dentine. To study the relationship between the expression of BSP and the formation of mineralized connective tissues, a cDNA probe to rat BSP was prepared for in situ hybridization analysis of developing fetal rat bones and teeth. When used for Northern hybridization analysis of rat bone marrow cells induced to differentiate into osteogenic cells by dexamethasone, the BSP cDNA revealed a specific induction of 1.6- and 2.0-kb mRNA species of BSP. In tissue sections a strong hybridization signal associated with osteoblasts was observed in areas of endochondral bone formation in the long bone metaphysis and condylar cartilage, and in the intramembranous bone of the calvaria and mandible. Hybridization reflecting a lower degree of expression was evident in cells of the transitional zone of mineralizing cartilage and in odontoblasts forming incisor dentine. Expression of BSP was also demonstrated in the hypertrophic cartilage cells in the long bone and condylar process. In contrast, expression of BSP could not be detected in the reserve or proliferative chondrocytes, fibroblasts and muscle cells. These studies demonstrate that the expression of BSP in bones and teeth is essentially restricted to cells directly involved in the formation of mineralizing connective tissue matrices, indicating that BSP has a specific role in biological mineralization and that it is a useful marker of bone formation.

Drug handling and patient compliance in an outpatient paediatric trial.

New routines for drug handling were used in a 24-week outpatient double-blind trial of naproxen versus acetylsalicylic acid in 80 patients with juvenile rheumatoid arthritis. The clinician ordered tablets from the pharmacy for each patient by stating name, weight and randomization number. The pharmacy dispensed the drugs in sealed and labelled 1-week medication containers. Totally, 2176 containers were packed and distributed to the patients. Two errors in ordering of drugs were detected. Patient compliance was studied by tablet count in used containers returned by 25 of the patients. The calculated compliance was 95%. The procedures for drug handling seem useful and may increase the validity of clinical trials. The staff at the local pharmacy can be valuable partners in the planning and performance of clinical drug trials.