Polarization-dependent discharge in fibers of semiconducting ladder-type polymer

We report results on polarization-dependent photoinduced discharge in oriented fibers and films of ladder-type, electron-transporting polymer poly (benzimidazobenzophenanthroline), BBL. The photocarrier generation efficiency in the fiber which is indicated by the rate of discharge, is found to be distinctly higher for light polarized parallel to the fiber axis as compared to the radially perpendicular direction . Similar results, with photocarrier generation efficiency anisotropy ~ 10 are obtained for oriented films. These observations are different from previously obtained results on polyparaphenylenevinylene (PPV). The results are compared with the polarization-dependent steady- state photoconductivity measurements. We interpret these results on the basis of molecular and macroscopic features of the material.Comment: This article has been accepted for publication in applied physics letters and tentatively to be published in March 12, 2001 issu

Model checking Branching-Time Properties of Multi-Pushdown Systems is Hard

We address the model checking problem for shared memory concurrent programs modeled as multi-pushdown systems. We consider here boolean programs with a finite number of threads and recursive procedures. It is well-known that the model checking problem is undecidable for this class of programs. In this paper, we investigate the decidability and the complexity of this problem under the assumption of bounded context-switching defined by Qadeer and Rehof, and of phase-boundedness proposed by La Torre et al. On the model checking of such systems against temporal logics and in particular branching time logics such as the modal $\mu$-calculus or CTL has received little attention. It is known that parity games, which are closely related to the modal $\mu$-calculus, are decidable for the class of bounded-phase systems (and hence for bounded-context switching as well), but with non-elementary complexity (Seth). A natural question is whether this high complexity is inevitable and what are the ways to get around it. This paper addresses these questions and unfortunately, and somewhat surprisingly, it shows that branching model checking for MPDSs is inherently an hard problem with no easy solution. We show that parity games on MPDS under phase-bounding restriction is non-elementary. Our main result shows that model checking a $k$ context bounded MPDS against a simple fragment of CTL, consisting of formulas that whose temporal operators come from the set {\EF, \EX}, has a non-elementary lower bound

Virtual Customer: Communication for E-Business

Volume 2 Issue 7 (July 2014

Anatomical variations of testicular artery: a review

The testicular arteries (TAs) also known as internal spermatic arteries are long and slender arteries usually arising from the anterolateral aspect of the abdominal aorta, 2.5 cm to 5 cm caudal to the renal arteries. The variation in TAs may be found with respect to their origin, number or course. They can originate from the abdominal aorta itself at an abnormal level. If not arising from abdominal aorta the TA variants may arise from renal artery, suprarenal artery or any one of the lumbar arteries. Rarely it can arise from common or internal iliac artery, or from the superior epigastric artery. The most common variation with respect to origin of TA was found in association with renal vessels. In regard to their number, double TA was found to be most common and with respect to course most common variation was arched TA over ipsilateral renal vein. The arched TA at times on right side had a retrocaval course. Occurrence of TA variants is explained with embryology and the knowledge of its clinical significance is essential for future surgeons for designing vascular surgeries. Four studies had attempted to classify TA variants regarding their origin, number and course but they could not accommodate recently found TA variants. This led to our new proposed classification

Solution of the Lane-Emden Equation Using the Bernstein Operational Matrix of Integration

Lane-Emden's equation has fundamental importance in the recent analysis of many problems in relativity and astrophysics including some models of density profiles for dark matter halos. An efficient numerical method is presented for linear and nonlinear Lane-Emden-type equations using the Bernstein polynomial operational matrix of integration. The proposed approach is different from other numerical techniques as it is based on the Bernstein polynomial integration matrix. Some illustrative examples are given to demonstrate the efficiency and validity of the proposed algorithm