Injection locking at 2f of spin torque oscillators under influence of thermal noise.

Integration of Spin Torque Nano-Oscillators STNO's in conventional microwave circuits means that the devices have to meet certain specifications. One of the most important criteria is the phase noise, being the key parameter to evaluate the performance and define possible applications. Phase locking several oscillators together has been suggested as a possible means to decrease phase noise and consequently, the linewidth. In this work we present experiments, numerical simulations and an analytic model to describe the effects of thermal noise in the injection locking of a tunnel junction based STNO. The analytics show the relation of the intrinsic parameters of the STNO with the phase noise level, opening the path to tailor the spectral characteristics by the magnetic configuration. Experiments and simulations demonstrate that in the in-plane magnetized structure, while the frequency is locked, much higher reference currents are needed to reduce the noise by phase locking. Moreover, our analysis shows that it is possible to control the phase noise by the reference microwave current (IRF) and that it can be further reduced by increasing the bias current (IDC) of the oscillator, keeping the reference current in feasible limits for applications.

Doxorubicin levels in the serum and ascites of patients with ovarian cancer.

AIMS: To investigate the diffusion and accumulation of doxorubicin metabolites in the ascites of patients with ovarian cancer following intravenous injection, as a model for intraperitoneal accumulation of drugs. METHODS: The concentrations of doxorubicin and its metabolites [Doxorubicinol (Dox-ol), 7-deoxydoxorubicinolone (7d-Dox-ol-on) and 7-deoxydoxorubicinone (7d-Dox-on)] were measured using high-performance liquid chromatography in the serum and in the ascites of seven patients with recurrent ovarian carcinoma suffering from symptomatic ascites and treated with intravenous doxorubicin. RESULTS: Doxorubicin metabolites accumulated in the peritoneal cavity. The concentrations of the doxorubicin metabolites were initially higher in the serum compared to the ascitic fluid, but following several hours the doxorubicin metabolites became higher in the ascites, and remained detectable in the ascites for up to 168h, long after disappearance from the serum. CONCLUSIONS: Doxorubicin metabolites accumulate in the ascites and are cleared more slowly from the peritoneal compartment than from the serum. Accumulation in the peritoneal cavity with prolonged half-life should be considered when administering medication in patients with ascites.

Driven kink in the frenkel-kontorova model

The dynamics of dc driven chain of harmonically interacting atoms in the external sinusoidal potential (the Frenkel-Kontorova model) is studied. It is shown that in the underdamped case the motion of the topological soliton (kink) becomes unstable at a high velocity due to excitation of the localized intrinsic kink mode (the discrete shape mode, or discrete breather) in the kink tail. When the amplitude of the breather's oscillation becomes large enough, it decays into a kink-antikink pair. The subsequent collision of newly created kink and antikink leads to a sharp transition to the running state, where all atoms of the chain slide over the external potential almost freely.