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

Synthesis and characterization of a new compound K6Ti2Nb14O42 in K2O-TiO2-Nb2O5 system

A new compound K6Ti2Nb14O42 was found in the ternary system K2O-TiO2-Nb2O5. The compound was characterized and investigated by electron probe, X-ray powder diffraction and differential thermal analysis. The transparent crystal of light yellow color in form of hexagon-thin plate can be grown by flux method. Further, its crystal structure was determined by four-circle diffractometer. K6Ti2Nb14 O-42 crystallizes in hexagonal system with unitcell parameters a = 9.1106 (5) X 10(-10) m, c = 12.0136 (9) X 10(-10) m, Z = 1 and space group P6(3)/mcm (193)