A. Romeo

Trends in spin-transfer-driven magnetization dynamics of CoFe∕AlO∕Py and CoFe∕MgO∕Py magnetic tunnel junctions

A spin-polarized current is able to excite magnetization dynamics in nanomagnets. A detailed theoretical study of dynamics in low and high field regimes in AlO and MgO magnetic tunnel junctions (MTJs) is presented, considering the maximum value of the applied current which comes from the breakdown voltage of the tunnel barrier. In low field regime, dynamics with a well-defined peak in frequency is observed. In high field regime, AlO MTJ presents the same behavior, while the magnetization in the MgO MTJ shows chaotic motion with a noisy spectrum. Lastly, an effect of the presence of a pinhole in the tunnel barrier is discussed.

Nanocontact spin-transfer oscillators based on perpendicular anisotropy in the free layer

Micromagnetic simulations are used to predict the behavior exhibited by spin-transfer oscillators when materials with perpendicular anisotropy are introduced in the “free” layer of nanocontact devices. Under a perpendicular-to-plane bias field, the frequency exhibits nonlinear dependence on the anisotropy field, mostly originated by the exchange-dominated propagating nature of spin-wave modes. The increase of frequency without using large bias fields makes it suitable for potential technological applications. A study of the feasibility of bias-field-free devices has been also performed deriving multiharmonic signals at gigahertz frequencies. Here, the magnetization describes a gyrotropic motion where both vortex-core polarization and rotation sense switch periodically.

Muscle-invasive bladder cancer in elderly-unfit patients with concomitant illness: can a curative radiation therapy be delivered?

Aims and background There is no standard treatment for elderly-unfit patients with muscle-invasive bladder cancer. Pelvic irradiation alone is an usual approach in this instance, and some reports have demonstrated that curative radiotherapy is feasible in elderly patients. To our knowledge, no data exist about the feasibility of a curative treatment in elderly patients with concomitant illness and a Charlson Comorbidity Index (an index of comorbidity that includes age) greater than 2. The main purpose of the present study was to establish the feasibility of irradiation in a cohort of elderly patients in poor general condition. Methods The records of 45 elderly-unfit patients (median age, 75 years; range, 70-85), with a comorbid Charlson score >2, treated with curative dose, planned continuous-course, external beam radiotherapy for muscle-invasive bladder cancer were reviewed. The patients were treated to a median total dose of 60 Gy (range, 56–64), with an average fractional dose of 190 ± 10 cGy using megavoltage (6–15 MV). All patients were treated with radiation fields encompassing the bladder and grossly involved lymph nodes with a radiographic margin of at least 1.5 cm. Results No treatment-related mortality and clinically insignificant acute morbidity was recorded. No patient was hospitalized during or after the irradiation because of gastrointestinal or urogenital side effects. In one patient a week rest from therapy was necessary due a febrile status. Median survival was 21.5 months; overall 3- and 5-year survival was 36% and 19.5%, respectively. Conclusions Elderly-unfit patients with comorbidities and >70 years of age can be submitted to radical pelvic irradiation. The results observed in this retrospective analysis have encouraged us to use non-palliative radiotherapy doses in these patients with muscle-invasive bladder cancer.

Magnetization dynamics in CoFe∕AlO/Permalloy and CoFe∕MgO/Permalloy magnetic tunnel junctions

This paper presents a theoretical study about the effect of nonidealities in the shape of elliptical cross sectional area of magnetic tunnel junctions on the magnetization dynamics driven by spin-polarized currents (no applied field). The set of nonideal shapes has been computed from scanning electron microscopy images directly. The polarization function deduced by Slonczewski in 2005 [Phys. Rev. B 71, 024411 (2005)] has been used for the simulations, considering the polarization factor independent of the bias. Depending on the shape, results of micromagnetic simulations show that the main steps of the magnetization dynamics do not change qualitatively, but in contrast, (a) other modes (defect modes) are excited, (b) a shift in the excited main mode is observed, and (c) the spatial distribution of the main mode changes.

Induction Chemotherapy to Weekly Paclitaxel Concurrent with Curative Radiotherapy in Stage IV (M0) Unresectable Head and Neck Squamous Cell Carcinoma: a Dose Escalation Study

Abstract The purpose was to determine the maximum tolerated dose (MTD) of weekly paclitaxel with concurrent, daily irradiation in patients with unresectable head and neck squamous cell carcinoma previously submitted to induction chemotherapy. Patients with stage IV, and unresectable tumor and/or node/s were enrolled. Nine male patients were submitted to a course of paclitaxel 175 mg/m2 day 1 and cis-platin 75 mg/m2 day 2 given every 3 weeks for three courses. Curative radiothera-py (RT) started 3 weeks after the last cycle of chemotherapy with the goal of deliv-ering a total dose of 66-70 Gy. During RT weekly paclitaxel was administered for 6 courses if feasible; paclitaxel was given according to a dose escalation schema in cohorts of three patients. Dose level A, 30 mg/m2; dose level B, 40 mg/m2; dose level C, 50 mg/m2. During weekly paclitaxel the major toxicity was mucositis that required a treatment break in two of three patients in dose level C; mucositis grade 4 required interruption of paclitaxel administration in all these patients. RT can be given in a continuous fashion with weekly paclitaxel after induction chemotherapy. The MTD of weekly paclitaxel was 40 mg/m2.