Coherent quantum transport in narrow constrictions in the presence of a finite-range longitudinally polarized time-dependent field

We have studied the quantum transport in a narrow constriction acted upon by a finite-range longitudinally polarized time-dependent electric field. The electric field induces coherent inelastic scatterings which involve both intra-subband and inter-sideband transitions. Subsequently, the dc conductance G is found to exhibit suppressed features. These features are recognized as the quasi-bound-state (QBS) features which are associated with electrons making transitions to the vicinity of a subband bottom, of which the density of states is singular. Having valley-like instead of dip-like structures, these QBS features are different from the G characteristics for constrictions acted upon by a finite-range time-modulated potential. In addition, the subband bottoms in the time-dependent electric field region are shifted upward by an energy proportional to the square of the electric field and inversely proportional to the square of the frequency. This effective potential barrier is originated from the square of the vector potential and it leads to the interesting field-sensitive QBS features. An experimental set-up is proposed for the observation of these features.Comment: 8 pages, 4 figure

A Set-Theoretic Method for Verifying Feasibility of a Fast Explicit Nonlinear Model Predictive Controller

In this chapter an algorithm for nonlinear explicit model predictive control is presented. A low complexity receding horizon control law is obtained by approximating the optimal control law using multiscale basis function approximation. Simultaneously, feasibility and stability of the approximate control law is ensured through the computation of a capture basin (region of attraction) for the closed-loop system. In a previous work, interval methods were used to construct the capture basin (feasible region), yet this approach suffered due to slow computation times and high grid complexity. In this chapter, we suggest an alternative to interval analysis based on zonotopes. The suggested method significantly reduces the complexity of the combined function approximation and verification procedure through the use of DC (difference of convex) programming, and recursive splitting. The result is a multiscale function approximation method with improved computational efficiency for fast nonlinear explicit model predictive control with guaranteed stability and constraint satisfaction

Mesoscopic effects in tunneling between parallel quantum wires

We consider a phase-coherent system of two parallel quantum wires that are coupled via a tunneling barrier of finite length. The usual perturbative treatment of tunneling fails in this case, even in the diffusive limit, once the length L of the coupling region exceeds a characteristic length scale L_t set by tunneling. Exact solution of the scattering problem posed by the extended tunneling barrier allows us to compute tunneling conductances as a function of applied voltage and magnetic field. We take into account charging effects in the quantum wires due to applied voltages and find that these are important for 1D-to-1D tunneling transport.Comment: 8 pages, 7 figures, improved Figs., added Refs. and appendix, to appear in Phys. Rev.

Prognostic factors for outcomes of patients with refractory or relapsed acute myelogenous leukemia or myelodysplastic syndromes undergoing allogeneic progenitor cell transplantation

AbstractAllogeneic progenitor cell transplantation is the only curative therapy for patients with refractory acute myelogenous leukemia or myelodysplastic syndromes. To identify prognostic factors in these patients, we performed a retrospective analysis of transplantation outcomes. Patients were selected if they had undergone an allogeneic transplantation between January 1988 and January 2002 and were not in remission or first untreated relapse at the time of transplantation. A total of 135 patients were identified. The median age was 49.5 years (range, 19-75 years). At the time of transplantation, 39.3% of patients had not responded to induction therapy, 37% had not responded to first salvage therapy, and 23.7% were beyond first salvage. Forty-one patients (30%) received unrelated donor progenitor cells. Eighty patients (59%) received either a reduced-intensity or a nonmyeloablative regimen. A total of 104 (77%) of 135 patients died, with a median survival time of 4.9 months (95% confidence interval, 3.9-6.6 months). The median progression-free survival was 2.9 months (95% confidence interval, 2.5-4.2 months). A Cox regression analysis showed that Karnofsky performance status, peripheral blood blasts, and tacrolimus exposure during the first 11 days after transplantation were predictive of survival. These data support the use of allogeneic transplantation for patients with relapsed or refractory acute myelogenous leukemia/myelodysplastic syndromes and suggest that optimal immune suppression early after transplantation is essential for long-term survival even in patients with refractory myeloid leukemias

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

Pathogenesis of Penile Squamous Cell Carcinoma: Molecular Update and Systematic Review.

Penile squamous cell carcinoma (PSCC) is a rare but aggressive neoplasm with dual pathogenesis (human papillomavirus (HPV)-associated and HPV-independent). The development of targeted treatment is hindered by poor knowledge of the molecular landscape of PSCC. We performed a thorough review of genetic alterations of PSCC focused on somatic mutations and/or copy number alterations. A total of seven articles have been identified which, overall, include 268 PSCC. However, the series are heterogeneous regarding methodologies employed for DNA sequencing and HPV detection together with HPV prevalence, and include, in general, a limited number of cases, which results in markedly different findings. Reported top-ranked mutations involve TP53, CDKN2A, FAT1, NOTCH-1 and PIK3CA. Numerical alterations involve gains in MYC and EGFR, as well as amplifications in HPV integration loci. A few genes including TP53, CDKN2A, PIK3CA and CCND1 harbor both somatic mutations and copy number alterations. Notch, RTK-RAS and Hippo pathways are frequently deregulated. Nevertheless, the relevance of the identified alterations, their role in signaling pathways or their association with HPV status remain elusive. Combined targeting of different pathways might represent a valid therapeutic approach in PSCC. This work calls for large-scale sequencing studies with robust HPV testing to improve the genomic understanding of PSCC

Cosmological principle and honeycombs

We present the possibility that the gravitational growth of primordial density fluctuations leads to what can be considered a week version of the cosmological principle. The large scale mass distribution associated with this principle must have the geometrical structures known as a regular honeycombs. We give the most important parameters that characterize the honeycombs associated with the closed, open, and flat FLRW models. These parameters can be used to determine by means of observations which is the appropriate honeycomb. For each of these honeycombs, and for a nearly flat universe, we have calculated the probability that a randomly placed observer could detect the honeycomb as a function of the density parameters.Comment: 16 pages, 3 figures. Minor revisions to reflect version published in Class.Quant.Gra

Channel Length Scaling of MoS2 MOSFETs

In this article, we investigate electrical transport properties in ultrathin body (UTB) MoS2 two-dimensional (2D) crystals with channel lengths ranging from 2 {\mu}m down to 50 nm. We compare the short channel behavior of sets of MOSFETs with various channel thickness, and reveal the superior immunity to short channel effects of MoS2 transistors. We observe no obvious short channel effects on the device with 100 nm channel length (Lch) fabricated on a 5 nm thick MoS2 2D crystal even when using 300 nm thick SiO2 as gate dielectric, and has a current on/off ratio up to ~109. We also observe the on-current saturation at short channel devices with continuous scaling due to the carrier velocity saturation. Also, we reveal the performance limit of short channel MoS2 transistors is dominated by the large contact resistance from the Schottky barrier between Ni and MoS2 interface, where a fully transparent contact is needed to achieve a high-performance short channel device.Comment: 22 pages, 6 figures; ACS Nano, ASAP, 201