Dynamics of a FitzHugh-Nagumo system subjected to autocorrelated noise

We analyze the dynamics of the FitzHugh-Nagumo (FHN) model in the presence of colored noise and a periodic signal. Two cases are considered: (i) the dynamics of the membrane potential is affected by the noise, (ii) the slow dynamics of the recovery variable is subject to noise. We investigate the role of the colored noise on the neuron dynamics by the mean response time (MRT) of the neuron. We find meaningful modifications of the resonant activation (RA) and noise enhanced stability (NES) phenomena due to the correlation time of the noise. For strongly correlated noise we observe suppression of NES effect and persistence of RA phenomenon, with an efficiency enhancement of the neuronal response. Finally we show that the self-correlation of the colored noise causes a reduction of the effective noise intensity, which appears as a rescaling of the fluctuations affecting the FHN system.Comment: 13 pages, 10 figure

AR function in promoting metastatic prostate cancer.

Prostate cancer (PCa) remains a leading cause of cancer-related death in the USA. While localized lesions are effectively treated through radical prostatectomy and/or radiation therapy, treatment for metastatic disease leverages the addiction of these tumors on the androgen receptor (AR) signaling axis for growth and disease progression. Though initially effective, tumors resistant to AR-directed therapeutics ultimately arise (a stage of the disease known as castration-resistant prostate cancer) and are responsible for PCa-specific mortality. Importantly, an abundance of clinical and preclinical evidence strongly implicates AR signaling cascades in the development of metastatic disease in both early and late stages, and thus a concerted effort has been made to delineate the AR-specific programs that facilitate progression to metastatic PCa. A multitude of downstream AR targets as well as critical AR cofactors have been identified which impinge upon both the AR pathway as well as associated metastatic phenotypes. This review will highlight the functional significance of these pathways to disseminated disease and define the molecular underpinnings behind these unique, AR-driven, metastatic signatures

Solid Waste Landfill Performance During the 1994 Northridge Earthquake

The performance of 22landfills in the Los Angeles area during the January 17, 1994 Northridge earthquake has been investigated. Observations of damage at these landfills indicate that the overall performance of solid waste landfills was encouraging. None of the surveyed landfills showed any signs of major damage. However, one geosynthetic-lined landfill experienced two tears in the geomembrane liner. Most landfills within 30 km of the zone of energy release experienced some form of cracking in the soil cover. Beyond approximately 40 km from the zone of energy release, little to no damage was observed

Effects of colored noise in short overdamped Josephson junction

We investigate the transient dynamics of a short overdamped Josephson junction with a periodic driving signal in the presence of colored noise. We analyze noise induced phenomena, specifically resonant activation and noise enhanced stability. We find that the positions both of the minimum of RA and maximum of NES depend on the value of the noise correlation time \u3c4_c. Moreover, in the range where RA is observed, we find a non-monotonic behavior of the mean switching time as a function of \u3c4_c

Relaxation phenomena in classical and quantum systems

et al.Relaxation phenomena in three different classical and quantum systems are investigated. First, the role of multiplicative and additive noise in a classical metastable system is analyzed. The mean lifetime of the metastable state shows a nonmonotonic behavior with a maximum as a function of both the additive and multiplicative noise intensities. In the second system, the simultaneous action of thermal and non-Gaussian noise on the dynamics of an overdamped point Josephson junction is studied. The effect of a Lévy noise generated by a Cauchy-Lorentz distribution on the mean lifetime of the superconductive metastable state, in the presence of a periodic driving, is investigated. We find resonant activation and noise enhanced stability in the presence of Lévy noise. Finally, the time evolution of a quantum particle moving in a metastable potential and interacting with a thermal reservoir is analyzed. Within the Caldeira-Legget model and the Feynman-Vernon functional approach, we obtain the time evolution of the population distributions in the position eigenstates of the particle, for different values of the thermal bath coupling strength.This work was partially supported by MIUR (Ministero dell’Istruzione dell’Universita‘ e della Ricerca), CNISM (Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia) and the Russian Foundation for Basic Research (project 11-02-01418). This work was also partially supported by the EU through Grant No. PITN-GA-2009-234970 and the Joint Italian Japanese Laboratory on “Quantum Technologies” of the Italian Ministry of Foreign Affairs.Peer Reviewe

HDAC6 mediates the acetylation of TRIM50

The E3 Ubiquitin ligase TRIM50 promotes the formation and clearance of aggresome-associated polyubiquitinated proteins through HDAC6 interaction, a tubulin specific deacetylase that regulates microtubule-dependent aggresome formation. In this report we showed that TRIM50 is a target of HDAC6 with Lys-372 as a critical residue for acetylation. We identified p300 and PCAF as two TRIM50 acetyltransferases and we further showed that a balance between ubiquitination and acetylation regulates TRIM50 degradatio