X-Ray Magnetic Circular Dichroism in Altermagnetic α-MnTe.

Altermagnetism is a recently identified magnetic symmetry class combining characteristics of conventional collinear ferromagnets and antiferromagnets, that were regarded as mutually exclusive, and enabling phenomena and functionalities unparalleled in either of the two traditional elementary magnetic classes. In this work we use symmetry, ab initio theory, and experiments to explore x-ray magnetic circular dichroism (XMCD) in the altermagnetic class. As a representative material for our XMCD study we choose α-MnTe with compensated antiparallel magnetic order in which an anomalous Hall effect has been already demonstrated. We predict and experimentally confirm a characteristic XMCD line shape for compensated moments lying in a plane perpendicular to the light propagation vector. Our results highlight the distinct phenomenology in altermagnets of this time-reversal symmetry breaking response, and its potential utility for element-specific spectroscopy and microscopy.

Valence-state mixing and reduced magnetic moment inFe3-δGeTe2single crystals with varying Fe content probed by x-ray spectroscopy.

We present a spectroscopic study of the magnetic properties ofFe3-δGeTe2single crystals with varying Fe content, achieved by tuning the stoichiometry of the crystals. We carried out x-ray absorption spectroscopy and analyzed the x-ray circular magnetic dichroism spectra using the sum rules, to determine the orbital and spin magnetic moments of the materials. We find a clear reduction of the spin and orbital magnetic moment with increasing Fe deficiency. Magnetic susceptibility measurements show that the reduction in magnetization is accompanied by a reduced Curie temperature. Multiplet calculations reveal that the Fe2+state increasingly mixes with a higher valence state when the Fe deficiency is increased. This effect is correlated with the weakening of the magnetic moment. As single crystals are the base material for exfoliation processes, our results are relevant for the assembly of 2D magnetic heterostructures.

Direct Observation of a Localized Magnetic Soliton in a Spin-Transfer Nanocontact.

We report the direct observation of a localized magnetic soliton in a spin-transfer nanocontact using scanning transmission x-ray microscopy. Experiments are conducted on a lithographically defined 150 nm diameter nanocontact to an ultrathin ferromagnetic multilayer with perpendicular magnetic anisotropy. Element-resolved x-ray magnetic circular dichroism images show an abrupt onset of a magnetic soliton excitation localized beneath the nanocontact at a threshold current. However, the amplitude of the excitation ≃25° at the contact center is far less than that predicted (⪅180°), showing that the spin dynamics is not described by existing models.

X-ray Detection of Transient Magnetic Moments Induced by a Spin Current in Cu.

We have used a MHz lock-in x-ray spectromicroscopy technique to directly detect changes in magnetic moment of Cu due to spin injection from an adjacent Co layer. The elemental and chemical specificity of x rays allows us to distinguish two spin current induced effects. We detect the creation of transient magnetic moments of 3×10^{-5}µ_{B} on Cu atoms within the bulk of the 28 nm thick Cu film due to spin accumulation. The moment value is compared to predictions by Mott's two current model. We also observe that the hybridization induced existing magnetic moments at the Cu interface atoms are transiently increased by about 10% or 4×10^{-3}µ_{B} per atom. This reveals the dominance of spin-torque alignment over Joule heat induced disorder of the interfacial Cu moments during current flow.

Practices for caring in nursing: Brazilian research groups.

BACKGROUND: The present study considers the production of knowledge and the interactions in the environment of research and their relationships in the system of caring in nursing and health. AIM: To elaborate a theoretical model of the organization of the practices used for caring, based on the experiences made by the research groups of administration and management in nursing, in Brazil. METHODS: The study is based on grounded theory. Twelve leaders of research groups, working as professors in public universities in the south and the south-east of Brazil, distributed in sample groups, were interviewed. FINDINGS: The core phenomenon 'research groups of administration and management in nursing: arrangements and interactions in the system of caring in nursing' was derived from the categories: conceptual bases and contexts of the research groups; experiencing interactions in the research groups; functionality of the research groups; and outputs of the research groups. The research groups are integrated in the system of caring in nursing. CONCLUSIONS: The activities of the Brazilian administration and management in nursing research groups are process oriented and in a process of constant renovation, socially relevant, operate in a complex scenario and contribute to the advancement of the organizations of the system of caring in nursing through strengthening the connection among academia, service and community.

Readout of an antiferromagnetic spintronics system by strong exchange coupling of Mn2Au and Permalloy.

In antiferromagnetic spintronics, the read-out of the staggered magnetization or Néel vector is the key obstacle to harnessing the ultra-fast dynamics and stability of antiferromagnets for novel devices. Here, we demonstrate strong exchange coupling of Mn2Au, a unique metallic antiferromagnet that exhibits Néel spin-orbit torques, with thin ferromagnetic Permalloy layers. This allows us to benefit from the well-established read-out methods of ferromagnets, while the essential advantages of antiferromagnetic spintronics are only slightly diminished. We show one-to-one imprinting of the antiferromagnetic on the ferromagnetic domain pattern. Conversely, alignment of the Permalloy magnetization reorients the Mn2Au Néel vector, an effect, which can be restricted to large magnetic fields by tuning the ferromagnetic layer thickness. To understand the origin of the strong coupling, we carry out high resolution electron microscopy imaging and we find that our growth yields an interface with a well-defined morphology that leads to the strong exchange coupling.

Imaging of domain wall inertia in Permalloy half-ring nanowires by time-resolved photoemission electron microscopy.

Using photoemission electron microscopy, we image the dynamics of a field pulse excited domain wall in a Permalloy nanowire. We find a delay in the onset of the wall motion with respect to the excitation and an oscillatory relaxation of the domain wall back to its equilibrium position, defined by an external magnetic field. The origin of both of these inertia effects is the transfer of energy between energy reservoirs. By imaging the distribution of the exchange energy in the wall spin structure, we determine these reservoirs, which are the basis of the domain wall mass concept.

Domain-wall depinning assisted by pure spin currents.

We study the depinning of domain walls by pure diffusive spin currents in a nonlocal spin valve structure based on two ferromagnetic Permalloy elements with copper as the nonmagnetic spin conduit. The injected spin current is absorbed by the second Permalloy structure with a domain wall, and from the dependence of the wall depinning field on the spin current density we find an efficiency of 6×10{-14} T/(A/m{2}), which is more than an order of magnitude larger than for conventional current induced domain-wall motion. Theoretically we find that this high efficiency arises from the surface torques exerted by the absorbed spin current that lead to efficient depinning.

Gadolinium Enhancement of the Aneurysm Wall in Unruptured Intracranial Aneurysms Is Associated with an Increased Risk of Aneurysm Instability: A Follow-Up Study.

BACKGROUND AND PURPOSE: Previous studies have suggested that gadolinium enhancement of the wall of unruptured intracranial aneurysms on MR imaging may reflect aneurysm wall instability. However, all previous studies were cross-sectional. In this longitudinal study, we investigated whether aneurysm wall enhancement is associated with an increased risk of aneurysm instability. MATERIALS AND METHODS: We included all patients 18 years of age or older with ≥1 unruptured aneurysm from the University Medical Center Utrecht, the Netherlands, who were included in 2 previous studies with either 3T or 7T aneurysm wall MR imaging and for whom it was decided not to treat the aneurysm but to monitor it with follow-up imaging. We investigated the risk of growth or rupture during follow-up of aneurysms with and without gadolinium enhancement of the aneurysm wall at baseline and calculated the risk difference between the 2 groups with corresponding 95% confidence intervals. RESULTS: We included 57 patients with 65 unruptured intracranial aneurysms. After a median follow-up of 27 months (interquartile range, 20-31 months), growth (n = 2) or rupture (n = 2) was observed in 4 of 19 aneurysms (21%; 95% CI, 6%-54%) with wall enhancement and in zero of 46 aneurysms (0%; 95% CI, 0%-8%) without enhancement (risk difference, 21%; 95% CI, 3%-39%). CONCLUSIONS: Gadolinium enhancement of the aneurysm wall on MR imaging is associated with an increased risk of aneurysm instability. The absence of wall enhancement makes it unlikely that the aneurysm will grow or rupture in the short term. Larger studies are needed to investigate whether aneurysm wall enhancement is an independent predictor of aneurysm instability.

Direct observation and imaging of a spin-wave soliton with p-like symmetry.

Spin waves, the collective excitations of spins, can emerge as nonlinear solitons at the nanoscale when excited by an electrical current from a nanocontact. These solitons are expected to have essentially cylindrical symmetry (that is, s-like), but no direct experimental observation exists to confirm this picture. Using a high-sensitivity time-resolved magnetic X-ray microscopy with 50 ps temporal resolution and 35 nm spatial resolution, we are able to create a real-space spin-wave movie and observe the emergence of a localized soliton with a nodal line, that is, with p-like symmetry. Micromagnetic simulations explain the measurements and reveal that the symmetry of the soliton can be controlled by magnetic fields. Our results broaden the understanding of spin-wave dynamics at the nanoscale, with implications for the design of magnetic nanodevices.

Quantitation of vancomycin and its crystalline degradation product (CDP-1) in human serum by high performance liquid chromatography.

The delayed clearance of vancomycin results in accumulation of vancomycin crystalline degradation product, CDP-1, in the bodies of renally impaired patients. The 2 isomers, CDP-1-M (major) and CDP-1-m (minor), of CDP-1 are antibiotically inactive but cross-react with some immunoassays that use polyclonal antibodies resulting in falsely elevated results. A high performance liquid chromatographic (HPLC) method was developed to quantitate vancomycin and CDP-1 in the serum of renal patients. After solid phase extraction of 200 microliters serum, the separation of vancomycin, the 2 isomers of CDP-1 and the internal standard (cefazolin) was accomplished by gradient HPLC on a reversed phase C18 column with detection at 210 nm. Linearity was established from 1 to 25 and 25 to 100 micrograms ml-1 vancomycin and 1 to 25 micrograms ml-1 CDP-1. Coefficients of variation for vancomycin and CDP-1 were 3.3-8.6% (n = 10) and 2.8-5.2% (n = 8).

Ecgonine methyl ester, a major metabolite of cocaine.

Most assays for the identification of cocaine use are aimed at detection of benzoylecgonine, a major urinary metabolite. Gas chromatography assays require derivatization of benzoylecgonine. Recently, ecgonine methyl ester (methylecgonine) has been shown to be major urinary metabolite of cocaine in man after oral administration. These results indicate that ecgonine methyl ester is a prominent urinary metabolite after street use of cocaine, which primarily involves intranasal application and intravenous injection rather than ingestion. Advantages of GC/MS analysis for ecgonine methyl ester in identifying cocaine use include the ability to chromatograph it on common stationary phases without derivatization and its early elution.

[Rural nursing]. / Enfermagem rural.

This paper describes the experience of a teacher and four students of the Federal University of Rio Grande do Sul within a sitting of members of a rural social movement that claims for land in Brazil. The work began with an activity of familiarization and ended up being an extension project. The aim of this project was the development of a Nursing assistencial model for the population of the rural area, considering the specificities of this movement, wishing to adapt Nursing teaching to this reality. The author sought for theoretical references in Breilh (1999) and Freire (1981). The activities were developed in 1996 and consisted of home care and group education.

Relationship between nonadiabaticity and damping in permalloy studied by current induced spin structure transformations.

By direct imaging we determine spin structure changes in Permalloy wires and disks due to spin transfer torque as well as the critical current densities for different domain wall types. Periodic domain wall transformations from transverse to vortex walls and vice versa are observed, and the transformation mechanism occurs by vortex core displacement perpendicular to the wire. The results imply that the nonadiabaticity parameter beta does not equal the damping alpha, in agreement with recent theoretical predictions. The vortex core motion perpendicular to the current is further studied in disks revealing that the displacement in opposite directions can be attributed to different polarities of the vortex core.

Spatially resolved dynamic eigenmode spectrum of Co rings.

The spatially resolved eigenmode spectrum of micrometer-sized Co ring elements has been determined by means of combined vector network analyzer ferromagnetic resonance and time resolved magneto-optic Kerr effect measurements. Up to 5 resonant eigenmodes were observed in the frequency range from 45 MHz to 20 GHz as a function of an external magnetic bias field. A well-defined mode structure was found for the two equilibrium states (vortex and onion) which correspond to distinctive spatial modes. The effect of dynamic inter-ring coupling on the modes in the remanent states was evinced. The experimental results are found to be in good agreement with those of micromagnetic simulations. Our results demonstrate that, in analogy to the well-defined static equilibrium magnetic states of ring elements, the eigenmode spectra of this high symmetry geometry consist of a well-defined and simple mode structure.

Determination of methotrexate in serum by high-performance liquid chromatography.

A sensitive high-performance liquid chromatographic method with ultraviolet detection was developed to quantitate methotrexate in serum-based calibrators, controls and patient samples. Sample clean-up was achieved with C18 Sep-Pak Classic cartridges. The chromatographic separation was accomplished on a 5-microns Ultrasphere ODS Beckman column. 8-Chlorotheophylline was used as an internal standard. The method was validated by recovery, linearity, accuracy and precision studies. Two standard curves were constructed to cover the high and the low ends of the calibrator range (0.05-1.0 mumol/l). Response was found linear over the whole range of the calibrator set with a correlation coefficient of 0.999 and 1.00 for the low-level and the high-level curves, respectively. Accuracy varied from 12% at the lowest level to 1.2% at the highest level. The precision study showed a C.V. of 14.4% at the lowest level and 3.3% at the highest level.

Intestinocystoplasty in combination with clean intermittent catheterization in the management of vesical dysfunction.

Intestinocystoplasty in combination with clean intermittent catheterization has been used in the management of 60 young patients with bladder dysfunction. Of the patients 39 (65 per cent) had the primary diagnosis of myelomeningocele, 8 had sacral agenesis, 3 had spinal cord tumors and 1 had spinal cord trauma. The remaining 9 patients had either congenital, surgical or traumatic loss of all or a large portion of the bladder. Of the 60 patients 30 had undergone prior urinary diversion, while the remaining 30 were considered failures with management by clean intermittent catheterization and medication. A total of 16 patients underwent ileocecocystoplasty, while 44 had augmentation with either cecum (8), sigmoid (18) or ileum (18). Mean followup was 4 years (range 16 months to 7 years). Fifty-nine patients have stable or improved renal function and the excretory urogram is stable or improved in all 60. Of the patients 38 (63 per cent) were considered dry after the initial bladder augmentation, while an additional 14 were rendered dry by a second procedure consisting of bladder neck reconstruction or placement of the artificial urinary sphincter, for a total of 52 (87 per cent) currently considered to be dry. Eleven patients have had at least 1 symptomatic urinary tract infection (18 per cent) and 21 had a positive urine culture but remained asymptomatic. In contrast to earlier beliefs, intestinocystoplasty can be applied effectively and appropriately to patients with bladder and urethral dysfunction. Intestinocystoplasty combined with clean intermittent catheterization offers a significant alternative to diversion in such patients.