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.

Néel Vector Induced Manipulation of Valence States in the Collinear Antiferromagnet Mn2Au.

The coupling of real and momentum space is utilized to tailor electronic properties of the collinear metallic antiferromagnet Mn2Au by aligning the real space Néel vector indicating the direction of the staggered magnetization. Pulsed magnetic fields of 60 T were used to orient the sublattice magnetizations of capped epitaxial Mn2Au(001) thin films perpendicular to the applied field direction by a spin-flop transition. The electronic structure and its corresponding changes were investigated by angular-resolved photoemission spectroscopy with photon energies in the vacuum-ultraviolet, soft, and hard X-ray range. The results reveal an energetic rearrangement of conduction electrons propagating perpendicular to the Néel vector. They confirm previous predictions on the origin of the Néel spin-orbit torque and anisotropic magnetoresistance in Mn2Au and reflect the combined antiferromagnetic and spin-orbit interaction in this compound leading to inversion symmetry breaking.

Retraction: Néel Spin-Orbit Torque Driven Antiferromagnetic Resonance in Mn_{2}Au Probed by Time-Domain THz Spectroscopy [Phys. Rev. Lett. 120, 237201 (2018)].

Retraction of DOI: 10.1103/PhysRevLett.120.237201.

Néel Spin-Orbit Torque Driven Antiferromagnetic Resonance in Mn_{2}Au Probed by Time-Domain THz Spectroscopy.

We observe the excitation of collective modes in the terahertz (THz) range driven by the recently discovered Néel spin-orbit torques (NSOTs) in the metallic antiferromagnet Mn_{2}Au. Temperature-dependent THz spectroscopy reveals a strong absorption mode centered near 1 THz, which upon heating from 4 to 450 K softens and loses intensity. A comparison with the estimated eigenmode frequencies implies that the observed mode is an in-plane antiferromagnetic resonance (AFMR). The AFMR absorption strength exceeds those found in antiferromagnetic insulators, driven by the magnetic field of the THz radiation, by 3 orders of magnitude. Based on this and the agreement with our theory modeling, we infer that the driving mechanism for the observed mode is the current-induced NSOT. Here the electric field component of the THz pulse drives an ac current in the metal, which subsequently drives the AFMR. This electric manipulation of the Néel order parameter at high frequencies makes Mn_{2}Au a prime candidate for antiferromagnetic ultrafast memory applications.

Writing and reading antiferromagnetic Mn2Au by Néel spin-orbit torques and large anisotropic magnetoresistance.

Using antiferromagnets as active elements in spintronics requires the ability to manipulate and read-out the Néel vector orientation. Here we demonstrate for Mn2Au, a good conductor with a high ordering temperature suitable for applications, reproducible switching using current pulse generated bulk spin-orbit torques and read-out by magnetoresistance measurements. Reversible and consistent changes of the longitudinal resistance and planar Hall voltage of star-patterned epitaxial Mn2Au(001) thin films were generated by pulse current densities of ≃107 A/cm2. The symmetry of the torques agrees with theoretical predictions and a large read-out magnetoresistance effect of more than ≃6% is reproduced by ab initio transport calculations.

Molecular structures of carbonyl-linked bis(dioxolene) complexes: can a carbonyl group act as an effective ferromagnetic coupler?

Molecular structures of two bis(ZnIIdioxolene) complexes are described: (TpCum,MeZn)(2)1-H2 (C106H123.50B2N12O10Zn2), tetragonal, P4/ncc, a = 25.1810(2) A, b = 25.1810(2) A, c = 34.7744(2) A, alpha = 90 degrees, beta = 90 degrees, gamma = 90 degrees, Z = 8; (TpCum,MeZn)(2)1-H (C101H120B2N12O6Zn2), triclinic, P1, a = 13.6624(2) A, b = 13.80920(10) A, c = 26.62340(10) A, alpha = 96.6910(10) degrees, beta = 91.8560(10) degrees, gamma = 109.0190(10) degrees, Z = 2. One of the complexes, (TpCum,MeZn)(2)1-H2, has two protonated catecholate ligands, while the other complex, (TpCum,MeZn)(2)1-H, has one protonated catecholate and one semiquinone ligand. When reacted with PbO2, a labile S = 1, bis(ZnIIsemiquinone) complex is formed in which the two semiquinones are attached to a common carbonyl group.

A bis-bidentate dioxolene ligand induces thermal hysteresis in valence tautomerism interconversion processes.

The use of a bis-bidentate ligand in a solid cobalt dioxolene complex affords the necessary cooperative properties that lead to thermal hysteresis in a valence tautomeric interconversion equilibrium.

Synthesis and structure of a complex having a quartet ground state with three entirely different spin carriers: nitronyl nitroxide, o-semiquinone, and CuII.

A "spin diverse" S = 3/2 ground-state complex, NN-SQCuTpCum,Me, has been prepared. The three S = 1/2 spin carriers are nitronyl nitroxide (NN), o-semiquinone (o-SQ), and cupric ion. The solid-state structure of the ZnII derivative, NN-SQZnTpCum,Me (C56H69BN8O4Zn), was determined: monoclinic, P2(1)/c, a = 12.5781(12) A, b = 17.7408(17) A, c = 24.440(2) A, alpha = 90.00 degrees, beta = 98.240(2) degrees, gamma = 90.00 degrees, Z = 4. The results of X-ray structural characterization of the ZnII derivative suggest substantial interaction between the two spin carriers NN and o-SQ. Indeed, strong intramolecular exchange coupling has been determined by variable-temperature magnetic susceptibility studies. Intraligand ferromagnetic exchange is considerably greater than kT, such that only the triplet state is populated at 300 K, and CuII-ligand exchange is ferromagnetic, with J = +75 cm-1.

Laparoscopic cholecystectomy in acute cholecystitis.

The authors retrospective analyze the role of golden standard laparoscopic cholecystectomy for the treatment of acute cholecystitis. They make a comparison between the results of 50 early cholecystectomy and 44 "a froid" cholecystectomy (operation was postponed until 6 weeks after acute cholecystitis had healed). From January 1997 to December 1998 536 laparoscopic cholecystectomies were performed. In 491 cases (91.6%) laparoscopic, and in 45 cases (8.4%) traditional (opening) method was indicated. Converted cholecystectomies were in 36 cases (7.3%). Agreeing to the literature they can determine the optimal timing of the operation in 72 hours from the onset of acute cholecystitis [2, 4]. In this group (first group) there were 50 cases, with 14 conversions (28%). In the second group (postponed, so called "a froid" phase) there were 44 patients. From this group was the intraoperative diagnosis serious acute-subacute cholecystitis in 24 cases (54.54%) causing complicated laparoscopic cholecystectomy and resulting in 11 conversions (11/44: 25%). The causes of the higher rate of conversion were the grave inflammation and slow dissection of central formation. There were no serious complication and mortality in both groups. It was diagnosed bile leak (two cases) which ceased spontaneously, one haematoma in abdominal layers, and one trocar's hernia. The authors have recommended the laparoscopic cholecystectomy for early diagnose acute cholecystitis in order to prevent the complications and reduce the sick-leave. Supporting their viewpoint the most important clinical end economical facts are: the recurrence of inflammation forced urgent surgery and caused more complication in the course of "a froid" phase there were scrutable anatomical situation the patients recovered in a shorter time.

Synchronically performed laparoscopic cholecystectomy and hernioplasty.

Cholecystectomies and hernioplasties are the two most frequently performed surgical interventions. The laparoscopic technique can be offered for the simultaneous treatment with both operating indications. The synchronical operation can give all the advantages of the minimally invasive technique. Authors had performed laparoscopic cholecystectomy with laparoscopic hernioplasty in five cases. Two inguinal and three postoperative hernias were reconstructed. The cholecystectomy was performed with a "three punction method", and the hernioplasty by using the same approach, completed by inserting a fourth assisting trocar as required. The hernial ring was covered with an intraperitoneally placed mesh, which was fixed by staplers (the so-called "IPOM-method": intraperitoneal on-lay mesh). There was no intra-, nor postoperative complication. The hernioplasty combined with laparoscopic cholecystectomy did not have effect on postoperative pain and nursing time. The return to the normal physical activity was short, similar to laparoscopic hernioplasty (in 1-2 weeks). Authors conclude that the simultaneous, synchronous laparoscopic cholecystectomy and hernioplasty is recommended and should be the method of choice because it is more advantageous for patients.

Eliminating needless testing in intensive care--an information-based team management approach.

OBJECTIVE: To determine if the application of an information-based management system in adult intensive care units (ICU) can produce sustained decreases in the use of laboratory resources and costs. DESIGN: Interventional study with prospective data collection on consecutive patients admitted during three time periods. SETTING: A 10-bed adult surgical ICU and an eight-bed adult medical ICU in a tertiary care hospital. PATIENTS: All patients admitted to an ICU during a 7-month baseline period (n = 647), a 1-yr intervention period (n = 1236), and a 2-yr follow-up period (n = 2349). INTERVENTIONS: Using a management database to track the use of 123 laboratory investigations during the baseline period, nine frequently ordered investigations (determination of blood gases, glucose, potassium, electrocardiogram, chest radiograph, sodium, chloride, complete blood count with differential, and serum osmolality) were targeted for reduction. Specific policies were developed by a multidisciplinary committee within the ICU to reduce the utilization of these laboratory, radiology, and cardiology tests. The policies were applied to all patients admitted during the 1-yr intervention period and during the 2-yr follow-up period. MEASUREMENTS AND MAIN RESULTS: A 25% reduction was observed in the frequency of all 123 monitored tests during the intervention period. The most dramatic reductions occurred in the nine targeted tests (range 19% to 46%) (p < .001). There were significant reductions in only 13 of the untargeted 114 investigations during this period. Potential annual cost savings were > $150,000 Canadian. No increases in ICU mortality rate, length of stay, or cost of medication were observed, and the reductions in the frequency of targeted tests were maintained during the 2-yr follow-up period. CONCLUSIONS: Application of an information-based multidisciplinary management system in the ICU can produce marked and sustained reductions in unnecessary testing in a cost-effective manner. Although rationing of intensive care services may be necessary, reducing needless testing can be a safe and effective cost-containment strategy in the ICU.

[Relations between food poisoning and ascariasis]. / Zusammenhänge zwischen Lebensmittelvergiftung und Ascariase.

During the examination of faeces for the causative agents of food poisoning, the search was also extended to the occurrence of worm eggs. Ascaris lumbricoides eggs occurred six times more frequently in persons affected with food poisoning than in consumers who were not harmed by the intake of poisoned food. This relationship was observed in non-specific cases of food poisoning and in those of unknown aetiology, whereas it was less pronounced in cases of specific poisoning. This difference has not been confirmed for Trichuris trichiura. It is safe to say that Ascaris infection increases the disposition to manifestation of symptoms of intoxication and represents, among other things, a factor in the aetiology of food poisoning.

[Additional studies of the pathogenicity of aerobic spore-forming organisms (genus Bacillus) for mice]. / Weitere Studien über die Mäusepathogenität aerober Sporenbildner (Genus Bacillus).

An investigation of the parenteral pathogenic potential of aerobic spore-forming bacteria (genus Bacillus) in mice revealed that in the case of i.p. inoculation (0.5 ml suspension, 10(6)-10(7) viable cells per ml) only B. cereus was pathogenic, killing appr. one half of the inoculated animals (293 out of 577). Other bacilli (B. subtilis, B. megaterium, B. pumilus etc.) administered intraperitoneally did not produce any lethal effect. If inoculated intracerebrally, B. cereus killed appr. 90% of the mice (138 out of 155), while for other bacilli the rate was appr. 50% only (260 out of 529). It is suggested that most of the aerobic spore-forming organisms cultured from cases of hospital infections are B. cereus which, however, does not completely exclude the presence of other species.

[Cases of severe enteric disease caused by spore-forming aerobic bacteria in Hungary (author's transl)]. / Durch aerobe Sporenbildner verursachte, schwer verlaufende Darmerkrankungen in Ungarn.

For a long time there has been doubt the facultative enteropathogenicity of saprophytic bacteria of the genus Bacillus; even today, it is not generally recognized. The simultaneous presence of numerous factors is known to be required for the genesis of enteric diseases (food poisoning). Among bacilli, B. cereus is the most pathogenic one, however, other species may also be involved. In Central Europe, food poisoning caused by bacteria become manifest after a latent period of 6-10 h. Gastric and intestinal convulsions which last for 8-12 h hand diarrhea with watery stools are observed. Nausea, vomiting, headache, and fever are rare symptoms. Cases of food poisoning observed in America and England were mainly characterized by nausea and vomiting lasting 4-6 h after a latent period of 1-2 h. both types have shown a mild course. In the present communication, 5 comparatively severe cases are described, of which 2 occurred in children. In 3 cases. foods of animal origin were incriminated as vehicles of infection, which had not been stated for earlier cases. The potential of spore-forming organisms, in particular of B. cereus, for causing severe disease should not be overlooked.