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This article discusses a study that used magnetic resonance imaging (MRI) to analyze blood flow in a rabbit model during different cannulation strategies for extracorporeal circulation (ECC) in cardiac surgery. The study found that the blood flow in the ascending aorta, aortic arch, and descending aorta was higher during antegrade perfusion compared to retrograde perfusion. However, there were no significant differences in cerebral or visceral perfusion between the two strategies. This study provides valuable insights into the optimal ECC cannulation strategy for cardiac surgery. [Extracted from the article]

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. Néel spin-orbit torques can occur in antiferromagnets with broken inversion symmetry, such as Mn2Au, and have garnered significant interest recently, as they allow for the electrical control of the antiferromagnetic ordering. Here, Behovits et al. apply intense terahertz electric fields to Mn2Au and observe the deflection of the Néel vector on ultrafast time scales due to Néel spin-orbit torques. [ABSTRACT FROM AUTHOR]

We demonstrate the reversible current-induced motion of 180° antiferromagnetic domain walls in a CuMnAs device. By controlling the magnitude and direction of the current pulse, the position of a domain wall can be switched between three distinct pinning sites. The domain wall motion is attributed to a field-like spin–orbit torque that induces the same sense of rotation on each magnetic sublattice, owing to the crystal symmetry of CuMnAs. Domain wall motion is observed for current densities down to ≈ 2.5 × 1 0 10 A/m2 at room temperature. [ABSTRACT FROM AUTHOR]

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. Antiferromagnets have an inbuilt resilience to external magnetic fields and intrinsically fast dynamics, properties that have garnered interest in the hope that they could be used for antiferromagnet memories. Central to this are Neel spin-orbit torques, which can switch the individual sublattices of the antiferromagnet. Here, Reimers et al demonstrate complete and reversible current induced switching of the Neel vector in Mn2Au. [ABSTRACT FROM AUTHOR]

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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 in 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. [ABSTRACT FROM AUTHOR]