Vortex Dynamics in Bi2Sr2CaCu2O8 Single Crystal with Low Density Columnar Defects Studied by Magnetic Force Microscope

We have studied vortex dynamics in Bi₂Sr₂CaCu₂O₈ single crystal with low density columnar defects by using a magnetic force microscope. Single crystal Bi₂Sr₂CaCu₂O₈ sample was irradiated by 1.3 GeV uranium ion to form artificial pinning centers along the crystalline c-axis. The irradiation dose corresponded to a matching field of 20 gauss. The radius of an individual vortex is approximately 140 nm, which is close to the penetration depth of this material. Magnetic force microscope (MFM) images show that intrinsic crystalline defects such as stacking fault dislocations are very effective pinning centers for vortices in addition to the pinning centers due to ion bombardment. By counting the number of vortex, we found that the flux trapped at each pinning center is a single flux quantum. At higher magnetic field, the vortex structure showed an Abrikosov lattice disturbed only by immobile vortices located at pinning centers. When increasing or decreasing the external magnetic field, the spatial distribution of vortices showed a Bean model like behavior.     

Reliability assessment of polysilicon MEMS structures under mechanical fatigue loading

This paper examines the current status and methodologies of study of material and system reliability in Microelectromechanical Systems (MEMS). This includes: a review of the current literature in the area of MEMS regarding failure analysis experimental investigations; testing methods and philosophies for material characterization and possible mechanistic analytical solutions for estimating material properties. The paper proposes a reliability framework that encompasses all the available information. This statistical platform will enable the MEMS design engineer to distill all the available information in the literature into a stand-alone semi-empirical material reliability model, and a holistic system-level model for a complete system.     

Growth of GaAs on polycrystalline silicon-on-insulator

The growth of GaAs on polycrystalline silicon-on-insulator (SOI) substrates by metal organic vapor phase epitaxy using a two-step growth process was studied in this work. We have compared the variation of the growth temperature and the thickness of the initial GaAs epilayer in the structures grown on polycrystalline SOI to ones grown on SOI and epi-Si. Structural properties were studied using high-resolution X-ray diffraction (XRD). The growth temperature had a strong effect on the FWHM of the (0 0 4) XRD curve in structures grown on SOI and epi-Si. In the case of polycrystalline SOI the effect was not as strong. Optical properties of the samples in which the optically active layer consisted of self-organized In_0.5Ga_0.5As quantum dots were investigated by photoluminescence measurements. The photoluminescence intensity from structures grown on polycrystalline SOI was comparable to that from structures grown on SOI and epi-Si.     

Entropy Based Approach to Data Loss Reparation Through the Indeterminate Fine-Grained Parallel Computation

The new method of a gap recovery in symbol sequences is presented. A covering is combined from the suitable reasonably short strings of the parts of a sequence available for observation. Two criteria are introduced to choose the best covering. It must yield the maximum of entropy of a frequency dictionary developed over the sequence obtained due to the recovery, if an overlapping combined from the copies of strings from the available parts of the sequence exists. The second criterion identifies the best covering in case when one has to use any string to cover the gap; here the best covering must yield the minimum of specific entropy of the frequency dictionary developed over the available parts of the sequence against the one developed over the entire sequence obtained due to the recovery. Kirdin kinetic machine which is the ideal fine-grained structureless computer has been used to resolve the problem of the reconstruction of a gap in symbol sequence.     

Ethernet-based passive optical local-area networks for fiber-to-the-desk application

We introduce optical local-area network (LAN) architectures based on multimode optical fiber and components, short wavelength lasers and detectors, and the widely used fast Ethernet protocol. These architectures are designed to lower the costs associated with passive optical LAN implementation. Further reduction in overall cost is achieved through decreased network downtime, lower maintenance cost, extended geometrical spans, and larger headroom for future capacity increase. These optically transparent networks represent a novel approach for implementing fiber-to-the-desk.     

Explicit Self-Regulated Strategy Development Versus Reciprocal Questioning: Effects on Expository Reading Comprehension Among Struggling Readers.

The effects of 2 rigorous strategic approaches to reading comprehension for 32 5th-grade students who struggle with reading were investigated. The first approach, TWA (Think before reading, think While reading, think After reading), was taught following explicit self-regulated strategy development instructional procedures (K. R. Harris & S. Graham. 1999). The second approach, reciprocal questioning (RQ), was taught following Cooperative ReQuest procedures developed by A. V. Manzo. U. C. Manzo, and T. H. Estes (2001). Compared with RQ students, TWA students improved significantly (with medium to large effect sizes) on 5 oral reading comprehension measures. There were no significant differences, however, between groups on 3 written comprehension measures, self-efficacy, or motivation. Students were positive about each intervention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)