Shot noise in resonant tunneling through a zero-dimensional state with a complex energy spectrum

We investigate the noise properties of a GaAs/AlGaAs resonant tunneling structure at bias voltages where the current characteristic is determined by single electron tunneling. We discuss the suppression of the shot noise in the framework of a coupled two-state system. For large bias voltages we observed super-Poissonian shot noise up to values of the Fano factor $\alpha \approx 10$.Comment: 4 pages, 4 figures, accepted for Phys. Rev.

Chemokine receptor expression in tumour islets and stroma in non-small cell lung cancer

<p>Abstract</p> <p>Background</p> <p>We have previously demonstrated that tumour islet infiltration by macrophages is associated with extended survival (ES) in NSCLC. We therefore hypothesised that patients with improved survival would have high tumour islet expression of chemokine receptors known to be associated with favourable prognosis in cancer. This study investigated chemokine receptor expression in the tumour islets and stroma in NSCLC.</p> <p>Methods</p> <p>We used immunohistochemistry to identify cells expressing CXCR1, CXCR2, CXCR3, CXCR4, CXCR5 and CCR1 in the tumour islets and stroma in 20 patients with surgically resected NSCLC. Correlations were made with macrophage and mast cell expression.</p> <p>Results</p> <p>There was increased expression of CXCR2, CXCR3, and CCR1 in the tumour islets of ES compared with poor survival (PS) patients (p = 0.007, 0.01, and 0.002, respectively). There was an association between 5 year survival and tumour islet CXCR2, CXCR3 and CCR1 density (p = 0.02, 0.003 and <0.001, respectively) as well as stromal CXCR3 density (p = 0.003). There was a positive correlation between macrophage density and CXCR3 expression (r_s= 0.520, p = 0.02) and between mast cell density and CXCR3 expression (r_s= 0.499, p = 0.03) in the tumour islets.</p> <p>Conclusion</p> <p>Above median expression of CXCR2, CXCR3 and CCR1 in the tumour islets is associated with increased survival in NSCLC, and expression of CXCR3 correlates with increased macrophage and mast cell infiltration in the tumour islets.</p

In Situ Electrochemical Quartz Crystal Microbalance Study of Potential Oscillations During the Electrodeposition of Cu/Cu₂O Layered Nanostructures

Application of a constant cathodic current to an electrode in an alkaline Cu(II) lactate solution results in oscillation of the electrode potential during the electrodeposition of copper/cuprous oxide layered nanostructures. The electrochemical quartz crystal microbalance (EQCM) is used for in situ phase analysis measurements of the nanoscale layers and the results are compared with bulk XRD measurements. The EQCM is also used to estimate the layer thicknesses and overall modulation wavelength of the nanostructures. We propose that Cu2U is deposited during the positive spikes in electrode potential, while a composite of Cu and Cu2U is deposited during the more negative plateau region of the oscillation. The modulation wavelength calculated from the EQCM is in good agreement with that observed with scanning electron microscopy. The EQCM is shown to be a useful tool for estimating layer thicknesses and phase compositions for layers that are too thin to be examined by other instrumental techniques

Potential Oscillations During the Electrochemical Self-assembly of Copper/Cuprous Oxide Layered Nanostructures

Layered nanostructures of copper metal and cuprous oxide are electrodeposited from alkaline solutions of CU(II) lactate at room temperature. No subsequent heat treatment is necessary to effect crystallization.The electrode potential spontaneously oscillates during constant-current deposition. at a fixed current density the oscillation period decreases as either the pH or temperature is increased. the oscillations are periodic in stirred solution, but show period doubling and evidence of quasi-periodic or chaotic behavior in unstirred solution. the phase composition and resistivity of the films can be controlled by varying the applied current density. the resistivity of the films can be varied over ten orders of magnitude. Scanning electron microscopy shows that the films are layered

Transverse-momentum fluctuations in π+p\pi^{+}p and K+pK^{+}p collisions at 250 GeV/c

We report results on event-by-event fluctuations of transverse momentum, Phi (p/sub t/), in pi /sup +/p and K/sup +/p collisions at 250 GeV/c. For the first time, their dependence on rapidity region, transverse momentum acceptance, multiplicity, mean transverse momentum per event, and on the correlation between transverse momentum and multiplicity are systematically presented. The results are compared with those from the PYTHIA Monte Carlo generator. The fluctuations under the same acceptance cuts as used in current heavy- ion experiments are also presented