Limiting shapes of birth-and-death processes on Young diagrams

We consider a family of birth processes and birth-and-death processes on Young diagrams of integer partitions of n. This family incorporates three famous models from very different fields: Rost?s totally asymmetric particle model (in discrete time), Simon?s urban growth model, and Moran?s infinite alleles model. We study stationary distributions and limit shapes as n tends to infinity, and present a number of results and conjectures.     

Maximal spanning trees,asset graphs and random matrix denoising in the analysis of dynamics of financial networks

We study the time dependence of maximal spanning trees and asset graphs based on correlation matrices of stock returns. In these networks the nodes represent companies and links are related to the correlation coefficients between them. Special emphasis is given to the comparison between ordinary and denoised correlation matrices. The analysis of single- and multi-step survival ratios of the corresponding networks reveals that the ordinary correlation matrices are more stable in time than the denoised ones. Our study also shows that some information about the cluster structure of the companies is lost in the denoising procedure. Cluster structure that makes sense from an economic point of view exists, and can easily be observed in networks based on denoised correlation matrices. However, this structure is somewhat clearer in the networks based on ordinary correlation matrices. Some technical aspects, such as the random matrix denoising procedure, are also presented.     

Functional fluid jetting performance optimization

The manufacturing method utilizing digital printing technology offers alternatives to create electronic structures to be used even in microelectronic applications. Material deposition based on digital inkjet technology offers advantages over both traditional mask-etch technologies and other printing methods. Inkjet technology works in an additive manner, reducing material consumption and the amount of created waste. Additionally, the digital nature of the process allows flexible production, e.g., rapid design changes, quick prototyping, and small, customized series. This research paper introduces ink jetting performance optimization utilized in a concept where discrete components and bare silicon chips were integrated in a single module with ink jetted interconnections. Jetting optimization of fluids enhances the droplet placement and volume accuracy that is a critical issue when forming interconnections for dense IC circuits. The overall drop placement error in jet printing is a combination of several error sources such as mechanical, dynamical and material related issues. However, the largest error portion is induced by a single printhead. The printhead related errors can be detected by observing the flight behavior after firing from the printhead nozzle. This paper focuses on optimizing the performance of ejected droplets during flight, i.e., drop formation sequence and minimum flight time variance. The average drop velocities of drops fired from separate printhead nozzles can be used to evaluate the difference in placement on substrate, which in worse case may lead to electrical wiring failures. The performance optimization was done by analyzing the initial state, modeling the drop velocity during flight, optimizing the process parameters to satisfy the model, and accepting the model after verification. Two inks, conductive and dielectric, were evaluated and improvement in placement accuracy was achieved through enhanced uniformity in drop average velocities, a dimensionless number, coefficient of variation was enhanced from 0.051 to 0.040,with conductive ink and from 0.111 to 0.049 with dielectric ink, thus decreasing the velocity related drop placement error.     

A fully integrated CMOS voltage regulator for supply-noise-insensitive charge pump PLL design

In this paper, a new design of on-chip CMOS voltage regulator, which provides two stable power supplies to charge pump and voltage controlled oscillator (VCO) in charge pump phase-locked loop (PLL), is presented. A power supply noise rejection (PSNR) whose peaking is less than −40 dB is achieved over the entire frequency spectrum for VCO supply. The voltage regulator provides maximum 14 mA current, and static current is about 780 μA at 3.3 V. Based on the proposed voltage regulator, a PLL clock generator has been developed and measured in the AMS 0.35 μm CMOS process. Operating at 160 MHz, a period jitter of 13.64 ps was measured under a clean power supply, while period jitter became 16.24 ps under a power supply modulated with a 400 mV, 10 kHz square wave.     

Quantaloids,enriched categories and automata theory

This article is intended to be an survey article outlining how the theory of quantaloids and categories enriched in them provides an effective means of analyzing both automata and tree automata. The emphasis is on the unification of concepts and how categorical methods provide insight into various calculations and theorems, both illuminating the original presentation as well as yielding conceptually simpler proofs. Proofs will be omitted and the emphasis is on providing the reader (even a relatively inexperienced one) with an understanding of the basic constructions and results.     

Electron ionization and chemical ionization fragmentation of o/p isomers of bisphenol-A with tandem mass spectrometry

The fragmentation of o/p isomers of bisphenol-A was examined by using collisionally activated decomposition and the tanden mass spectrometric techniques. Also chemical ionization was performed using methane, isobutane and ammonia. The o/p position of the hydroxy groups in the bisphenol-A molecule directed the fragmentation both in electron and chemical ionization.     

Polygon Posets and the Weak Order of Coxeter Groups

We explore the connection between polygon posets, which is a class of ranked posets with an edge-labeling which satisfies certain polygon properties, and the weak order of Coxeter groups. We show that every polygon poset is isomorphic to a join ideal in the weak order, and for Coxeter groups where no pair of generators have infinite order the converse is also true.The class of polygon posets is seen to include the class of generalized quotients defined by Björner and Wachs, while itself being included in the class of alternative generalized quotients also considered by these authors. By studying polygon posets we are then able to answer an open question about common properties of these two classes.     

FREE RADICALS FROM PHOTODECOMPOSITION OF BISPHENOL-A

Abstract— Irradiation of 2,2-bis-(4-hydroxyphenyl)-propane (bisphenol-A) with UV light causes photo-decomposition of the compound. Spin-trapping with α-phenyl-N-tert-butyl-nitrone showed that free radicals were cleaved from the molecule. No direct ESR-spectroscopic information concerning the structure of the remaining radical skeleton could be obtained. Gas chromatographic mass spectrometric analysis of the decomposition products indicated the existence of a semiquinone structure following cleavage of a methyl radical from 2,2-bis-4–(hydroxyphenyl)-propane. The capacity of 2,2-bis-(4- hydroxyphenyl)-propane to give rise to radicals might explain its photoallergenic properties.