A systematic approach to determining the constitutive parameters of metamaterials in the context of transformation electromagnetics

A novel systematic method for the retrieval of the constitutive electromagnetic parameters of metamaterials is presented. The analysis is focused on the important class of metamaterials consisting of a stack of planar periodic structures. A complete characterization of the effective medium is obtained by retrieving all the components of the permeability and permittivity tensors and accounting for both spatial and time dispersion. The capability of characterizing the anisotropy is especially useful in the implementation via metamaterials of the results of transformation electromagnetics, which requires a full control of all the components of the constitutive dyadic parameters. Numerical results are presented to demonstrate how the retrieved parameters can be used to obtain an accurate prediction of the scattering from a finite metamaterial slab

Effects of different enrichment devices on some welfare indicators of post-weaned undocked piglets

Two experimental trials were carried out in order to test the effectiveness of different environmental enrichments in improving the welfare of weaned pigs. A total of 120 undocked piglets was used. In trial one, group C1 received a metal chain and group WL a wooden log mounted on a frame. In trial two, the enrichments proposed were a hanging chain (group C2), an edible block (group ED) and a wooden briquette (group WB) mounted on a frame. The effectiveness of the enrichments was assessed in terms of animal behaviour, cortisol from bristles, hematologic and hematic profiles, cutaneous (skin and tail) lesions. Growth parameters were also recorded. Although some differences were detected in growth parameters in trial 1 (with C1 group having better productive outcomes than WL group) and some minor differences were observed in animal behaviour in both trials, the overall welfare status did not differ among the experimental groups. On the other hand, no welfare issues emerged in groups C1 and C2, receiving the enrichment device which is generally believed to be scarcely attractive, i.e. the hanging chain. We can therefore conclude that, if no managerial errors are made (floor space availability, feed inadequacy, group stability, microclimate, illumination), under the tested experimental conditions, hanging chains can provide a sufficient environmental enrichment for undocked piglets, even when compared to more attractive enrichment

Narrow-band filtering by means of triangular meta-material resonators based on RF MEMS cantilevers in CPW configuration

Triangular resonators, designed by using Radio Frequency Micro Electro Mechanical Systems (RF MEMS) cantilevers in coplanar waveguide (CPW) configuration, have been proposed, fabricated on alumina and on silicon substrates and tested up to 40 GHz. They can be utilized as building blocks for realizing reconfigurable filters . A triangular split ring resonator has been etched in the cen- tral conductor of the CPW transmission line and the split is provided by the presence of a technologically actuated cantilever beam, i.e. with metal directly deposited without the sacrificial layer, to emulate the ideal actuation and to get preliminary information of the expected microwave response in comparison to numerical simulations. Two main configurations of the triangular transmission line have been studied for narrow-band microwave switching, the first one without the MEMS cantilever and the second one with a technologically actuated MEMS cantilever switch. Because of the contributions of both the resonator and the switch, the device has a narrow band filtering feature. Moreover, these geometries can also be characterized in the broad class of metamaterial devices, because the unit cell can be described by negative equivalent electric permit- tivity and/or magnetic permeability, by means of a trans- mission line parameters extraction method. This finding contributes to the possibility of miniaturization implemen- tations of the resonating structures. A simple but effective lumped element circuit for the modeling of the single triangular resonator is also presented

INFANT EPENDYMOMA IN A 10-YEAR AIEOP (ASSOCIAZIONE ITALIANA EMATOLOGIA ONCOLOGIA PEDIATRICA) EXPERIENCE WITH OMITTED OR DEFERRED RADIOTHERAPY

Purpose: The protocols of the 1990s omitted or delayed irradiation, using upfront chemotherapy to spare the youngest children with ependymoma the sequelae of radiotherapy (RT). We treated 41 children under the age of 3 years with intracranial ependymoma between 1994 and 2003. Patients and Methods: After surgery, chemotherapy was given as follows: regimen 1 with four blocks of vincristine, high-dose methotrexate 5 g/m(2), and cyclophosphamide 1.5 g/m(2) alternating with cisplatin 90 mg/m(2) plus VP16 450 mg/m(2) for 14 months; subsequently, regimen II was used: VEC (VCR, VP16 300 mg/m(2), and cyclophosphamide 3 g/m(2)) for 6 months. Radiotherapy was planned for residual tumor after the completion of chemotherapy or for progression. Results: We treated 23 boys and 18 girls who were a median 22 months old; 14 were given regimen I, 27 were given regimen II; 22 underwent complete resection, 19 had residual tumor. Ependymoma was Grade 2 in 25 patients and Grade 3 in 16; tumors were infratentorial in 37 patients and supratentorial in 4. One child had intracranial metastases; 29 had progressed locally after a median 9 months. Event-free survival was 26% at 3 and 5 years and 23% at 8 years. One child died of sepsis, and another developed a glioblastoma 72 months after RT. Progression-free survival was 27% at 3, 5, and 8 years, and overall survival was 48%, 37%, and 28% at 3, 5, and 8 years, respectively. Of the 13 survivors, 6 never received RT; their intellectual outcome did not differ significantly in those children than in those without RT. Conclusions: Our results confirm poor rates of event-free survival and overall survival for up-front chemotherapy in infant ependymoma. No better neurocognitive outcome was demonstrated in the few survivors who never received RT. (C) 2011 Elsevier Inc