Curvature-induced stabilization and field-driven dynamics of magnetic hopfions in toroidal nanorings.

Three dimensional magnetic textures are a cornerstone in magnetism research. In this work, we analyze the stabilization and dynamic response of a magnetic hopfion hosted in a toroidal nanoring with intrinsic Dzyaloshinskii-Moriya interaction simulating FeGe. Our results evidence that unlike their planar counterparts, where perpendicular magnetic anisotropies are necessary to stabilize hopfions, the shape anisotropy originated on the torus symmetry naturally yields the nucleation of these topological textures. We also analyze the magnetization dynamical response by applying a magnetic field pulse to differentiate among several magnetic patterns. Finally, to understand the nature of spin wave modes, we analyze the spatial distributions of the resonant mode amplitudes and phases and describe the differences among bulk and surface modes. Importantly, hopfions lying in toroidal nanorings present a non-circularly symmetric poloidal resonant mode, which is not observed in other systems hosting hopfions.

Dynamic and static properties of stadium-shaped antidot arrays.

In this work we performed a detailed numerical analysis on the static and dynamic properties of magnetic antidot arrays as a function of their geometry. In particular, we explored how by varying the shape of these antidot arrays from circular holes to stadium-shaped holes, we can effectively control the magnetic properties of the array. Using micromagnetic simulations we evidenced that coercivity is very sensitive to the shape of antidots, while the remanence is more robust to these changes. Furthermore, we studied the dynamic susceptibility of these systems, finding that it is possible to control both the position and the number of resonance peaks simply by changing the geometry of the holes. Thus, this work provides useful insights on the behavior of antidot arrays for different geometries, opening routes for the design and improvement of two-dimensional technologies.

Infection with human herpesvirus type 8 and kaposi's sarcoma in a central Italian area formerly endemic for malaria.

BACKGROUND: To estimate the prevalence of infection with human herpes virus type 8 (HHV8) and the incidence of Kaposi's sarcoma among HHV8-infected individuals, we conducted a population-based, cross-sectional study in Latina. This area of central Italy was formerly endemic for malaria and it is now covered by a population-based cancer registry. MATERIALS AND METHODS: Residual sera samples from 200 persons (100 men and 100 women) aged 50 years or older, randomly selected from a larger population-based survey on cardiovascular diseases, were tested for antibodies against HHV8. HHV8 seroprevalence and yearly incidence rates of Kaposi's sarcoma (KS) among HHV8-positive persons were computed. RESULTS: HHV8 infection was not significantly higher in men (9.0%, 95% CI: 3.4-14.6) than in women (6.0%, 95% CI: 1.3-10.7). The estimated yearly incidence rate of KS among HHV-positive persons was twice as high in men (1 : 2200) as in women (1 : 4110). CONCLUSION: These results were comparable to those derived from geographic areas at low risk for KS where malaria was not endemic (e. g. Malta). The seemingly higher incidence of KS among HHV8-positive men suggests that different cofactors for the two sexes are likely to play a role in KS etiology.

First Report of White Rust of Gerbera Caused by Albugo tragopogonis in North America.

In October, 1995, in Villa Guerrero, Mexico, white erumpent sori were detected on the undersurfaces of leaves of a bed of African daisy (Gerbera jamesonii H. Bolus ex J. D. Hook.). The white sori on the undersurfaces of leaves corresponded to chlorotic spots on the upper leaf surfaces. All gerbera plants examined were severely diseased. The gerbera planting was adjacent to a planting of chrysanthemums with symptoms of white rust caused by Puccinia horiana Henn. Symptoms on the leaves of the two crops looked similar, and therefore P. horiana was suspected of causing both diseases. However, when subepidermal sori (pustules) on Gerbera plants were examined microscopically, erumpent chains of round to cylindrical, hyaline to pale yellow sporangiospores borne on short club-shaped sporangiophores were found. The sporangiospores are typical of Albugo tragopogonis (Pers.) S. F. Gray, and it was concluded that the white rust found on gerbera in Villa Guerrero, Mexico, was caused by A. tragopogonis. This disease was reported on gerbera from Australia and New Zealand in 1965 (1) and from Spain in 1977 (2). Other hosts of A. tragopogonis include members in the genera Pericallis (cineraria), Centaurea (dusty miller, basket flower, cornflower, bachelor's-buttons), Ambrosia (common ragweed), Tragopogon (salsify), Antennaria (everlasting, pussytoes), Artemisia (wormwort, mugwort), Cirsium (thistle), Matricaria (false chamomile, pineapple weed), Iva (marshelder), Parthenium (guayule, American feverfew), and Xanthium (common cocklebur, spiny cocklebur). This is the first report of white rust of gerbera caused by A. tragopogonis in North America, and may represent a new disease problem for species of important floral crops in the future. References: (1) R. F. Doepel. J. Agric. West. Aust. Ser. 4 6:439, 1965. [Rev. Appl. Mycol. 45:80, 1966] (2) H. P. Plate and H. Kruber. Nachrichtenbl. Dtsch. Pflanzen-schutzdienst (Berlin) 29(11):169, 1977. [Rev. Plant Pathol. 57:204, 1978].

Impairment of human brain development: glycoconjugate and lipid changes in congenital athyroidism.

The brain glycoconjugates, glycosidases and lipids have been studied in a case of human congenital athyroidism never treated with hormonal replacement. Increase of membrane-bound mucopolysaccharides has been found in the grey matter. Total lipids in the white matter, and phospholipids, and total glycolipids and cholesterol in both white and grey matter were reduced. Sialic acid (NeuNAc) and hexosamines in the cytosol grey matter were significantly raised, while they were reduced in the membrane-bound grey fraction. These biochemical findings confirm impairment of the myelination process in human hypothyroidism as is well established in experimental hypothyroidism. The significant changes in the carbohydrate moieties of the brain glycoproteins focus attention on complex alterations of structure and function of the cell plasma membranes.