On finite complete rewriting systems and large subsemigroups

Let $S$ be a semigroup and $T$ be a subsemigroup of finite index in $S$ (that is, the set $S\setminus T$ is finite). The subsemigroup $T$ is also called a large subsemigroup of $S$. It is well known that if $T$ has a finite complete rewriting system then so does $S$. In this paper, we will prove the converse, that is, if $S$ has a finite complete rewriting system then so does $T$. Our proof is purely combinatorial and also constructive.Comment: We have made major changes to the paper and simplified most of the proof

Using NMR to Measure Fractal Dimensions

A comment is made on the recent PFG NMR measurements by Stallmach, et al. on water-saturated sands [Phys. Rev. Lett. 88, 105505 (2002)]. It is pointed out that the usual law for the time-dependent diffusion coefficient D(t) used by these authors is not valid for a fractal surface. It is shown that (1-D(t)/D0) \~ t^[(3-Ds)/2] at short times for a surface of fractal dimension Ds, where D0 is the bulk diffusion coefficient. Preliminary PFG NMR data on water saturated limestone and plastic beads are presented to illustrate this analysis.Comment: 1 page, 1 figur

Meson-Meson Scattering in Relativistic Constraint Dynamics

Dirac's relativistic constraint dynamics have been successfully applied to obtain a covariant nonperturbative description of QED and QCD bound states. We use this formalism to describe a microscopic theory of meson-meson scattering as a relativistic generalization of the nonrelativistic quark-interchange model developed by Barnes and Swanson.Comment: 5 pages, 1 figure in LaTex, talk present at the First Meeting of the APS Topical Group on Hadronic Physics (Fermilab, October 24-26, 2004

Monolayer protection for eletrochemical migration control in silver nanocomposite

©2006 American Institute of Physics. The electronic version of this article is the complete one and can be found online at: http://link.aip.org/link/?APPLAB/89/112112/1DOI:10.1063/1.2353813The authors introduced an effective approach of using monolayer-protected silver nanoparticles to reduce silver migration for electronic device interconnect applications. Formation of surface complex between the carboxylate anion and surface silver ion reduces the solubility and diffusivity significantly of migration components and therefore contributes to effective migration control. A fundamental understanding of the mechanism of silver migration control was conducted by studying the current-voltage relationships of the nanocomposites with a migration model. The control of silver migration enables the application of the silver composites in fine pitch and high performance electronic device interconnects

The effect of integration time on fluctuation measurements: calibrating an optical trap in the presence of motion blur

Dynamical instrument limitations, such as finite detection bandwidth, do not simply add statistical errors to fluctuation measurements, but can create significant systematic biases that affect the measurement of steady-state properties. Such effects must be considered when calibrating ultra-sensitive force probes by analyzing the observed Brownian fluctuations. In this article, we present a novel method for extracting the true spring constant and diffusion coefficient of a harmonically confined Brownian particle that extends the standard equipartition and power spectrum techniques to account for video-image motion blur. These results are confirmed both numerically with a Brownian dynamics simulation, and experimentally with laser optical tweezers.Comment: 12 pages, 6 figures, revtex4; published in Optics Express. http://www.opticsinfobase.org/abstract.cfm?URI=oe-14-25-1251

Recent Advances in High-k Nanocomposite Materials for Embedded Capacitor Applications

©2008 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or distribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.DOI: 10.1109/TDEI.2008.4656240In this paper, a wide variety of high dielectric constant (k) composite materials which have been developed and evaluated for embedded capacitor application are reviewed. Current research efforts toward achieving high dielectric performance including highk and low dielectric loss for polymer composites are presented. New insights into the effect of unique properties of the nanoparticle filler, filler modification and the dispersion between filler and polymer matrix on the dielectric properties of the nanocomposites are discussed in details

An improved single-step lysis protocol to measure luciferase bioluminescence in Plasmodium falciparum

This report describes the optimization and evaluation of a simple single-step lysis protocol to measure luciferase bioluminescence from genetically modified Plasmodium falciparum. This protocol utilizes a modified commercial buffer to improve speed of assay and consistency in the bioluminescence signal measured by reducing the manipulation steps required to release the cytoplasmic fraction. The utility of this improved assay protocol is demonstrated in typical assays that explore absolute and temporal gene expression activity

Double-Layer No-Flow Underfill Process for Flip-Chip Applications

©2003 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or distribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.No-flow underfill technology shows potential advances over the conventional underfill technology toward a low-cost flop-chip underfill process. However, due to the filler entrapment in between solder bumps and contact pads on board, no-flow underfills are mostly unfilled or filled with very low filler loading. The high coefficient of thermal expansion (CTE) of the polymer material has significantly lowered the reliability of flip chip assembly and has limited its application to large chip assemblies. This paper presents a double-layer no-flow underfill process approach to incorporate silica filler into a no-flow underfill. Two layers of underfills are applied on to the substrate before chip placement. The bottom underfill layer facing the substrate is fluxed and unfilled; the upper layer facing the chip is filled with silica fillers. The total filler loading of the mixture is estimated to be around 55 wt%. The material properties of each layer of underfills, the underfill mixture, and a control unfilled underfill are characterized using differential scanning calorimeter (DCS), thermo-mechanical analyzer (TMA), dynamic mechanical analyzer (DMA), and a stress rheometer. FB250 daisy-chained test chips are assembled on FR-4 boards using the novel approach. A 100% assembly yield of solder Interconnect is achieved with the double-layer no-flow underfill while in the single-layer no-flow underfill process, no solder joint yield is observed. Scanning electronic microscope (SEM) and optical microscope are used to investigate the cross-section of both assemblies. A US provisional patent has been filed for this invention