Observation of compact ferrimagnetic skyrmions in DyCo3 film.

Owing to the experimental discovery of magnetic skyrmions stabilized by the Dzyaloshinskii-Moriya and/or dipolar interactions in thin films, there is a recent upsurge of interest in magnetic skyrmions with antiferromagnetic spins in order to overcome the fundamental limitations inherent with skyrmions in ferromagnetic materials. Here, we report on the observation of compact ferrimagnetic skyrmions for the class of amorphous alloys consisting of 4f rare-earth and 3d transition-metal elements with perpendicular magnetic anisotropy, using a DyCo3 film, that are identified by combining X-ray magnetic scattering, scanning transmission X-ray microscopy, and Hall transport technique. These skyrmions, with antiparallel aligned Dy and Co magnetic moments and a characteristic core radius of about 40 nm, are formed during the nucleation and annihilation of the magnetic maze-like domain pattern exhibiting a topological Hall effect contribution. Our findings provide a promising route for fundamental research in the field of ferrimagnetic/antiferromagnetic spintronics towards practical applications.

Impact of Symmetry on Anisotropic Magnetoresistance in Textured Ferromagnetic Thin Films.

We report on the magnetoresistance of textured films consisting of 3d-ferromagnetic layers sandwiched by Pt. While the conventional cos^{2}φ behavior of the anisotropic magnetoresistance (AMR) is found when the magnetization M is varied in the film plane, cos^{2n}θ contributions (2n≤6) exist for rotating M in the plane perpendicular to the current. This finding is explained by the symmetry-adapted modeling of AMR of textured films demonstrating that the cos^{2}θ behavior cannot be used as a fingerprint for the presence of spin Hall magnetoresistance (SMR). Further, the interfacial MR contributions for Pt/Ni/Pt contradict the SMR behavior confirming the dominant role of AMR in all-metallic systems.

Population Modeling of Selexipag Pharmacokinetics and Clinical Response Parameters in Patients With Pulmonary Arterial Hypertension.

Selexipag (Uptravi) is an oral selective IP prostacyclin receptor agonist approved for the treatment of pulmonary arterial hypertension (PAH). The pivotal GRIPHON study was the largest clinical study ever conducted in PAH patients, providing long-term data from 1,156 patients. PAH comedication did not affect exposure to selexipag, while exposure to its active metabolite ACT-333679 was reduced by 30% when taken in combination, clinically not relevant in the context of individual dose up-titration. Using log-linear regression models linking model-predicted steady-state exposure to pharmacodynamics (PD), exposure to selexipag and ACT-333679 showed some statistically significant, albeit not clinically relevant, effects on exercise capacity, laboratory values, and the occurrence of prostacyclin-related adverse events, but not on vital signs or adverse events denoting hemorrhage. Using suitable modeling techniques, the GRIPHON study yielded clinically relevant data with limited burden of pharmacokinetics (PK) blood sampling, demonstrating that PK/PD modeling enables firm conclusions even with sparse PK and PD sampling.

Magnetic resonance imaging of the proximal upper extremity musculature in boys with Duchenne muscular dystrophy.

There is a pressing need for biomarkers and outcomes that can be used across disease stages in Duchenne muscular dystrophy (DMD), to facilitate the inclusion of a wider range of participants in clinical trials and to improve our understanding of the natural history of DMD. Quantitative magnetic resonance imaging (qMRI) and spectroscopy (MRS) biomarkers show considerable promise in both the legs and forearms of individuals with DMD, but have not yet been examined in functionally important proximal upper extremity muscles such as the biceps brachii and deltoid. The primary objective of this study was to examine the feasibility of implementing qMRI and MRS biomarkers in the proximal upper extremity musculature, and the secondary objective was to examine the relationship between MR measures of arm muscle pathology and upper extremity functional endpoints. Biomarkers included MRS and MRI measures of fat fraction and transverse relaxation time (T 2). The MR exam was well tolerated in both ambulatory and non-ambulatory boys. qMR biomarkers differentiated affected and unaffected participants and correlated strongly with upper extremity function (r = 0.91 for biceps brachii T 2 versus performance of upper limb score). These qMR outcome measures could be highly beneficial to the neuromuscular disease community, allowing measurement of the quality of functionally important muscles across disease stages to understand the natural history of DMD and particularly to broaden the opportunity for clinical trial participation.

Longitudinal measurements of MRI-T2 in boys with Duchenne muscular dystrophy: effects of age and disease progression.

Duchenne muscular dystrophy (DMD) is characterized by an increased muscle damage and progressive replacement of muscle by noncontractile tissue. Both of these pathological changes can lengthen the MRI transverse proton relaxation time (T2). The current study measured longitudinal changes in T2 and its distribution in the lower leg of 16 boys with DMD (5-13years, 15 ambulatory) and 15 healthy controls (5-13years). These muscles were chosen to allow extended longitudinal monitoring, due to their slow progression compared with proximal muscles in DMD. In the soleus muscle of boys with DMD, T2 and the percentage of pixels with an elevated T2 (⩾2SD above control mean T2) increased significantly over 1year and 2years, while the width of the T2 histogram increased over 2years. Changes in soleus T2 variables were significantly greater in 9-13years old compared with 5-8years old boys with DMD. Significant correlations between the change in all soleus T2 variables over 2years and the change in functional measures over 2years were found. MRI measurement of muscle T2 in boys with DMD is sensitive to disease progression and shows promise as a clinical outcome measure.

Spatial fluctuations of loose spin coupling in CuMn/Co multilayers.

A detailed investigation of magnetic impurity-mediated interlayer exchange coupling observed in Cu(0.94)Mn(0.06)/Co multilayers using polarized neutron reflectometry and magnetic x-ray techniques is reported. Excellent descriptions of temperature and magnetic field dependent biquadratic coupling are obtained using a variant of the loose spin model that takes into account the distribution of the impurity Mn ions in three dimensions. Positional disorder of the magnetic impurities is shown to enhance biquadratic coupling via a new contribution J(2)(fluct), leading to a temperature dependent canting of magnetic domains in the multilayer. These results provide measurable effects on RKKY coupling associated with the distribution of impurities within planes parallel to the interfaces.

Anisotropic interface magnetoresistance in Pt/Co/Pt sandwiches.

We report on an effect of reduced dimensionality on the magnetotransport in cobalt layers sandwiched by platinum. In a current in-plane geometry it is found that the resistivity depends on the magnetization orientation within the plane perpendicular to the current direction. The resistivity shows a symmetry adapted cos(2) dependence on the angle to the surface normal, with the maximum along the surface normal. The Co thickness dependence of the effect in Pt/Co/Pt sandwiches clearly points out that the mechanism behind this effect originates at the Co/Pt interfaces and is disparate to the texture induced geometrical size effect.

Computational fluid dynamic simulation to assess flow characteristics of an in vitro aneurysm model.

BACKGROUND: Modifications of in vitro aneurysm modeling to study the effects of morphology on flow dynamics are time consuming, costly and analysis tends to be more qualitative than quantitative. This study develops a virtual two-dimensional flow model replicating an in vitro aneurysm model and analyzes how changes in morphology modify flow characteristics. METHODS: Using finite volume analysis, a two-dimensional saccular aneurysm model was created with a configuration matching a published, experimental, in vitro model. Qualitative comparisons were made determining whether a two-dimensional fluid dynamic model can replicate the results of an in vitro model. Quantitative changes in flow patterns, wall shear stress, dynamic pressure and maximum velocities were assessed by modifying the shape of the neck and proximal dome without modifying the overall size of the aneurysm. RESULTS: A two-dimensional computational fluid dynamic model reproducing the shape of a published aneurysm demonstrated excellent qualitative fidelity to an in vitro flow model. Additional information regarding dynamic pressure, shear stress and velocity along the aneurysm neck and within the aneurysm dome were determined. Although all dimensions were kept constant, slight modifications of the neck and proximal dome resulted in quantitative changes in studied parameters, such as wall shear stress and dynamic pressure. CONCLUSIONS: Computer generated aneurysm flow models, when carefully developed, reproduce flow events within in vitro aneurysms providing objective data on biophysical parameters. Effective flow modeling of aneurysms depends on flow input, size of the parent vessel and aneurysm, and other factors. These data suggest that neck and proximal dome configuration, independent of size, are important characteristics of flow.

Field induced chirality in the helix structure of Dy/Y multilayer films and experimental evidence for Dzyaloshinskii-Moriya interaction on the interfaces.

Polarized neutron scattering experiments have demonstrated that Dy/Y multilayer structures possess a coherent spin helix with a preferable chirality induced by the magnetic field. The average chirality, being proportional to the difference in the left- and right-handed helix population numbers, is measured as a polarization-dependent asymmetric part of the magnetic neutron scattering. The magnetic field applied in the plane of the sample upon cooling below T(N) is able to repopulate the otherwise equal population numbers for the left- and right-handed helixes. The experimental results strongly indicate that the chirality is caused by Dzyaloshinskii-Moriya interaction due to the lack of the symmetry inversion on the interfaces.

On the use of infinite elements for the determination of optimal closure patterns based on stress analysis.

Solid infinite elements are used in conjunction with finite elements to compute the stress and displacement distribution resulting from the suturing of wounds of symmetric and nonsymmetric shapes in orthotropic, abdominal human skin. The optimal pattern of suturing of wounds are investigated from a stress perspective. Highly accurate, quantitative and qualitative improvements over the use of finite elements to approximate distant boundaries are obtained. Numerical results quantitatively agree with analytic results computed using complex analysis techniques. The technique used and the results obtained will aid surgeons in closing nonsymmetrical wounds on regions of the body that exhibit orthotropy.

Sunscreen standards tested with differently filtered solar simulators.

BACKGROUND: The COLIPA standard for solar simulators permits a range of spectral filtration. Published studies comparing the SPFs of sunscreen formulas show that a range of SPFs is generally expected between laboratories. Specifically, three studies determining the SPFs of sunscreen standards have been performed in a series of laboratories and differences exceeding 50% have been reported. No studies to date have specifically examined potential differences in performance of Standard Sunscreen Test Formulas with varying solar simulator spectra within the permitted range of optical filtration. METHODS: In a paired clinical trial, two SPF standard sunscreen formulas were tested using two solar simulators that complied with the COLIPA standard for solar simulators but were filtered differently. One solar simulator was filtered as supplied by the manufacturer and delivered a high percentage of UVB; the other solar simulator was modified by removing the visible absorbing filter to deliver energy more closely resembling sunlight in the UVA-1 part of the spectrum, with a lower percentage of UVB. RESULTS AND CONCLUSION: The result was that the SPF of each standard sunscreen was almost 50% greater with the unmodified solar simulator than with the modified solar simulator. In vitro evaluation of the sunscreen standards predicted similar differences due to the spectral differences of the solar simulators, which appears to rule out reciprocity failure. However, reciprocity failure of the control MEDs was observed. The total intensity of the modified lamp was approximately 3 times that of the unmodified lamp.

The Behavior Problems Inventory: an instrument for the assessment of self-injury, stereotyped behavior, and aggression/destruction in individuals with developmental disabilities.

The Behavior Problems Inventory (BPI-01) is a 52-item respondent-based behavior rating instrument for self-injurious, stereotypic, and aggressive/destructive behavior in mental retardation and other developmental disabilities. Items are rated on a frequency scale and a severity scale. The BPI-01 was administered by interviewing direct care staff of 432 randomly selected residents from a developmental center between the ages of 14 to 91 years. For 73% of those selected, at least one problem was endorsed on the BPI-01. A total of 43% showed self-injury, 54% stereotyped behavior, and 38% aggressive/destructive behavior. Confirmatory factor analysis and item-total correlations supported the three a priori factors. Analyses of variance (ANOVA) showed that of the variables age, sex, and level of mental retardation, only the latter had a significant effect on the BPI-01 total score, the SIB subscale score, and the Stereotyped Behavior subscale score. Aggression/destruction was not significantly related to any of the three variables. Individuals with a diagnosis of pervasive developmental disorder had higher scores on all three subscales than those without, whereas residents with a diagnosis of stereotyped movement disorder had higher Stereotyped Behavior scale scores than those without. The BPI-01 was found to be a reliable (retest reliability, internal consistency, and between-interviewer-agreement) and valid (factor and criterion validity) behavior rating instrument for problem behaviors in mental retardation and developmental disabilities with a variety of potentially useful applications. Strengths and limitations of the instrument are discussed.

Intramedullary pressure and pulmonary function during total knee arthroplasty.

Twenty-eight patients who underwent unilateral total knee arthroplasty and 20 patients who underwent simultaneous bilateral total knee arthroplasties participated in this study and were randomized to have either a fluted or round 10-mm diameter femoral intramedullary alignment rod used during surgery. The intramedullary rods were cannulated and connected with pressure tubing to a monitor which provided measurements of pressure at the tip of each rod. Arterial blood gas measurements on room air were obtained before and on the morning after surgery. An arterial line was placed and an arterial blood gas measurement was obtained at the time of skin incision and again after tourniquet release. Pulmonary shunt was calculated from the arterial blood gas measurements. Intramedullary pressure during rod insertion was significantly higher for the groups of patients having the round compared with the fluted rod. The change in pulmonary shunt during surgery was lowest for the patients in the unilateral group having the fluted rod and highest for the patients in the bilateral group having the round rod. A fluted rather than a round intramedullary alignment rod should be used to minimize intramedullary pressure and pulmonary shunting during unilateral and bilateral total knee arthroplasties.

Physical and behavioral findings in a pseudohermaphrodite American bison.

A pseudohermaphrodite American bison (Bison bison) behaved like an adult male when interacting with adult females, but like an adult female when interacting with adult males. Its chromosomes were a normal 60, XX and it had a uterus; but it had bilateral testes rather than ovaries. Skull measurements were intermediate between a bull and a cow. Gonadotrophin levels were typical of ovariectomized domestic cows or steers.

[The findings of color Doppler sonography in breast tumors]. / Befunde der Farb-Doppler-Sonographie bei Tumoren der Brustdrüse.

UNLABELLED: 72 histologically confirmed tumours of the breast--37 carcinomas and 35 benign tumours--for which mammograms were also available were examined by colour Doppler sonography. Vascularisation of benign processes showed at most 2 vessels (with the exception of 3 sarcoma phylloides and one proliferative mastopathy). Vascularisation clearly in excess of benign processes was observed in only 15 of the 37 carcinomas. In 33 of the carcinomas there was no doubt concerning the diagnosis preoperatively, in the remaining 4 the high vascularity was taken as an indication for surgery. CONCLUSION: In rare cases colour Doppler sonography can provide additional information in the presence of 'vascular' tumours. It is not possible to differentiate between poorly vascularised carcinomas and benign tumours.

Cefazolin-induced pseudomembranous colitis resulting in perforation of the sigmoid colon.

The seventh case of probable cefazolin-induced pseudomembranous colitis is reported. Perforation of the colon necessitated sigmoid resection. The postoperative course was protracted, and illustrates the difficulty of managing advanced pseudomembranous colitis when the oral route of antibiotic administration is not available. Although rare, pseudomembranous colitis related to cefazolin administration is a potentially fatal complication. The routine use of prophylactic antibiotics must be weighed against this possibility.

Surgical alteration of the mesosalpinx and its influence upon ovarian ovulatory function in the rabbit.

Ovarian ovulatory function as correlated with the production of corpora lutea was studied in 58 rabbits that were subjected to unilateral surgical procedures. Initially, a resection of 50% of the isthmus and 50% (n = 8) or all (n = 8) of the corresponding mesosalpinx was performed. Next, 50% of the ampulla and 50% (n = 7) or all (n = 8) of the corresponding mesosalpinx was resected. Finally, a variable length, either one third, two thirds, or all, of the ampulla (n = 27) was dissected from the adjacent mesosalpinx. After natural copulation of the animals, without administration of gonadotropin, the numbers of corpora lutea on the operated and control sides were counted. A slight but nonsignificant overall reduction in corpora lutea on the operated side was observed. This showed no correlation either to the amount of mesosalpinx resected or the proximity of the surgical procedure to the ovary. Also, no correlation was observed with the length of dissected ampullary part.