Technical challenges to a decentralized phone system

Changes that followed in the wake of the divestiture of AT&T are examined. One of these is the growth of new services, particularly ISDN and Switching System No.7 (SS7) services. Another is that setting standards has become a public and global, rather than strictly AT&T-determined, process. Waiting for standards is slowing innovations in the networks, because major equipment vendors to not want to take risks in developing new features, functions, and capabilities before standards are decided on. Service gains and lags in the new environment are discussed     

下一代网络的新业务

本文介绍下一代网络（NGN）各个层面的新技术及基于下一代网络（NGN）的语音、数据、多媒体等多种新业务的发展。     

Dependence of Photocurrent Enhancements in Quantum Dot (QD)‐Sensitized MoS2 Devices on MoS2 Film Properties

This report demonstrates highly efficient nonradiative energy transfer (NRET) from alloyed CdSeS/ZnS semiconductor nanocrystal quantum dots (QDs) to MoS₂ films of varying layer thicknesses, including pristine monolayers, mixed monolayer/bilayer, polycrystalline bilayers, and bulk‐like thicknesses, with NRET efficiencies of over 90%. Large‐area MoS₂ films are grown on Si/SiO₂ substrates by chemical vapor deposition. Despite the ultrahigh NRET efficiencies there is no distinct increase in the MoS₂ photoluminescence intensity. However, by studying the optoelectronic properties of the MoS₂ devices before and after adding the QD sensitizing layer photocurrent enhancements as large as ≈14‐fold for pristine monolayer devices are observed, with enhancements on the order of ≈2‐fold for MoS₂ devices of mixed monolayer and bilayer thicknesses. For the polycrystalline bilayer and bulk‐like MoS₂ devices there is almost no increase in the photocurrent after adding the QDs. Industrially scalable techniques are specifically utilized to fabricate the samples studied in this report, demonstrating the viability of this hybrid structure for commercial photodetector or light harvesting applications.     

A comparison of hardware implementations of the biorthogonal 9/7 DWT: convolution versus lifting

The filter bank approach for computing the discrete wavelet transform (DWT), which we call the convolution method, can employ either a nonpolyphase or polyphase structure. This work compares filter banks with an alternative polyphase structure for calculating the DWT-the lifting method. We look at the traditional lifting structure and a recently proposed "flipping" structure for implementing lifting. All filter bank structures are implemented on an Altera field-programmable gate array. The quantization of the coefficients (for implementation in fixed-point hardware) plays a crucial role in the performance of all structures, affecting both image compression quality and hardware metrics. We design several quantization methods and compare the best design for each approach: the nonpolyphase filter bank, the polyphase filter bank, the lifting and flipping structures. The results indicate that for the same image compression performance, the flipping structure gives the smallest and fastest, low-power hardware.     

The dynamic digital disk

The DVD (digital versatile disk) standard was the first format to truly unite the computer and consumer electronics environments-but it also launched an unprecedented debate about copy protection. The DVD is much more than just a new and improved version of the CD. Advances in optical storage, signal processing, and disc manufacturing technology have emerged in the 15 years or so since the CD's birth, and the new disc includes or builds on many of them. But DVD has also been a wake-up call for the motion picture and music industries, rousing them to ready their intellectual property for the new age of digital distribution of content. Four main specifications apply to the physical media itself: one each for the DVD-ROM, DVD-RAM, DVD-R, and DVD-RW. Next, at the logical layer, a common file system specification supports all applications. Named the Universal Disc Format (UDF), it was developed by the Optical Storage Trade Association, Santa Barbara, Calif. Together, the logical and physical layers support an overlying set of applications defined by the DVD-Video, DVD-Audio, and (as yet developmental) DVD-Professional specifications     

New Zealand or Aotearoa ? The Battle for Nationhood in the English Curriculum

Raymond Williams argued that education was centrally concerned with establishing and transmitting a 'selective tradition'. He identified three discourses that shape these processes of selection. This paper argues for the existence of a fourth discourse - 'education for nationhood'. The author outlines the concept of national identity and, using the history of schooling in New Zealand, argues that historically this discourse has been important in shaping educational curricula and practices. The paper focuses particularly on the role of literature in English as a subject, tracing the debate over the literature component in the latest revision of the 6th and 7th Form (senior secondary school) English curriculum in Aotearoa/New Zealand and arguing that this debate provides insight into the struggle taking place over the construction of nationhood in Aotearoa/New Zealand.     

Viral quantitative capillary electrophoresis for counting intact viruses

The quantification of a virus plays an important role in vaccine development, clinical diagnostics, and environmental contamination assays. In all these cases, it is essential to calculate the concentration or number of intact virus particles (ivp) and estimate the degree of degradation and contamination of virus samples. In this work, we propose a cost-efficient, robust method for the quantification and characterization of intact viruses based on capillary zone electrophoresis. This separation method is demonstrated on vaccinia virus (VV) with oncolytic properties. After virus sample preparation, the solution contains intact VV as well as broken viruses and residual DNA from the host cell used for preparation. Regulatory requirements limit the amount of the host cell DNA that can be present in vaccines or human therapeutics. We apply capillary electrophoresis to separate intact virus particles and the residual DNA and to measure the level of virus contamination with DNA impurities. Intercalating YOYO-1 dye is used to detect the encapsulated and free DNA by laser-induced fluorescence. After soft lysis of VV with proteinase K, all encapsulated DNA is dissolved to the free DNA. The change in peak areas and a DNA calibration curve help determine the initial concentration of intact viruses. This viral quantitative capillary electrophoresis (Viral qCE) is able to quantify the oncolytic vaccinia virus in the range of 10(6) to 10(12) ivp/mL.     

Equilibrium and dynamic swelling of polyacrylates

Polyacrylates were prepared by solution polymerization of partially neutralized acrylic acid at 37°C. The swelling behavior of the polyacrylates was examined using equilibrium and dynamic swelling studies. Equilibrium swelling studies in deionized water were used to determine the molecular weight between crosslinks using the Flory-Rehner theory. The amount of crosslinking agent incorporated into the network was a function of the nominal crosslinking ratio. Dynamic swelling studies in saline solutions were used to investigate the initial swelling rate for the polyacrylates. Swelling studies of the polyacrylates in saline solutions under load were used to elucidate the degree of swelling under load, the compliance, and sample elasticity.     

Antiplasticization behavior of polycaprolactone/polycarbonate-modified epoxies

Antiplasticization behavior was found in the polycaprolactone (PCL)/polycarbonate (PC)-modified epoxy system, cured with an aromatic amine. The initial modulus increased and the fracture toughness and the elongation at break decreased with the addition of the PCL/PC modifier. The glass transition temperature (T_g) decreased slightly. In this system, the antiplasticization phenomenon can be explained well by the formation of hydrogen bonding between the carbonyl groups in the PCL/PC and the hydroxyl groups in the epoxy. The hydrogen bonding proportion, as analyzed from Fourier transform infrared spectra, increased with the addition of PCL/PC up to 15 parts. This is consistent with the trend observed in the mechanical properties. It was thought that for antiplasticization to occur, a strong molecular interaction is necessary for a restriction of molecular motion, in turn decreasing the free volume of the matrix and thereby causing an increase in the modulus of the material. The dynamic mechanical thermal behavior of these systems was also studied. It was found that there was no change in the molecular weights between crosslinks, which excluded the effect of crosslink density on the changes of the properties. Instead, the activation energy was increased and the peak area was decreased for the β relaxation because of the restriction of the molecular motion by hydrogen bonding. The results indirectly support the hypothesis that the motion of the 2-hydroxypropyl ether is responsible for the β relaxation process.