Voice over IP versus voice over frame relay

This paper presents a comparison of the voice‐enabling features of the Internet protocol (IP) and frame relay (FR) networks. The discussion focuses on the issues that affect the quality of service of voice applications and the relative suitability of IP and FR for delivering voice applications. This independent assessment serves to assist network managers in decision‐making regarding suitable packetized voice solutions. Copyright © 2004 John Wiley & Sons, Ltd.     

Plasmonic near-electric field enhancement effects in ultrafast photoelectron emission: correlated spatial and laser polarization microscopy studies of individual ag nanocubes

Electron emission from single, supported Ag nanocubes excited with ultrafast laser pulses (λ = 800 nm) is studied via spatial and polarization correlated (i) dark field scattering microscopy (DFM), (ii) scanning photoionization microscopy (SPIM), and (iii) high-resolution transmission electron microscopy (HRTEM). Laser-induced electron emission is found to peak for laser polarization aligned with cube diagonals, suggesting the critical influence of plasmonic near-field enhancement of the incident electric field on the overall electron yield. For laser pulses with photon energy below the metal work function, coherent multiphoton photoelectron emission (MPPE) is identified as the most probable mechanism responsible for electron emission from Ag nanocubes and likely metal nanoparticles/surfaces in general.     

How pervasive are relative age effects in secondary school education?

Relative age effects (RAEs; R. H. Barnsley, A. H. Thompson, & P. E. Barnsley, 1985) convey school attainment (dis)advantages depending on whether one is relatively older or younger within annually age-grouped cohorts. In the present study, the authors examined the pervasiveness of RAEs by examining (a) attainment in 4 secondary school subjects, (b) attainment consistency across subjects, (c) pupils enrolled in gifted and talented programs, (d) pupils referred for learning support or identified as having special educational needs, and (e) whether RAEs were related to pupil attendance. For 2004–2005, attainment, program participation, and attendance data for 657 pupils (aged 11–14) at a secondary school in North England were analyzed. Relatively older pupils (i.e., September–November born) attained significantly higher in subjects (except for English), were more likely to attain consistently high scores across subject areas, and be enrolled in gifted and talented programs. In contrast, relatively younger pupils (i.e., January–August born) were overrepresented in learning support referrals and identified as having special educational needs, and were more likely to be among the lowest 20% of attainment and attendees, attending on average school 6 days less. RAEs are pervasive and systematic across the curriculum, implicating maturational and psychological mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Combining scanning tunneling microscope (STM) imaging and local manipulation to probe the high dose oxidation structure of the Si(111)-7×7 surface

Nano Research - Understanding the atomistic formation of oxide layers on semiconductors is important for thin film fabrication, scaling down conventional devices and for the integration of emerging...     

Gold nanocages: from synthesis to theranostic applications

Gold nanostructures have garnered considerable attention in recent years for their potential to facilitate both the diagnosis and treatment of cancer through their advantageous chemical and physical properties. The key feature of Au nanostructures for enabling this diverse array of biomedical applications is their attractive optical properties, specifically the scattering and absorption of light at resonant wavelengths due to the excitation of plasmon oscillations. This phenomenon is commonly known as localized surface plasmon resonance (LSPR) and is the source of the ruby red color of conventional Au colloids. The resonant wavelength depends on the size, shape, and geometry of the nanostructures, providing a set of knobs to manipulate the optical properties as needed. For in vivo applications, especially when optical excitation or transduction is involved, the LSPR peaks of the Au nanostructures have to be tuned to the transparent window of soft tissues in the near-infrared (NIR) region (from 700 to 900 nm) to maximize the penetration depth. Gold nanocages represent one class of nanostructures with tunable LSPR peaks in the NIR region. These versatile nanostructures, characterized by hollow interiors and ultrathin, porous walls, can be prepared in relatively large quantities using a remarkably simple procedure based on the galvanic replacement between Ag nanocubes and aqueous chloroauric acid. The LSPR peaks of Au nanocages can be readily and precisely tuned to any wavelength in the NIR region by controlling their size, wall thickness, or both. Other significant features of Au nanocages that make them particularly intriguing materials for biomedical applications include their compact sizes, large absorption cross sections (almost five orders of magnitude greater than those of conventional organic dyes), and their bio-inertness, as well as a robust and straightforward procedure for surface modification based on Au-thiolate chemistry. In this Account, we present some of the most recent advances in the use of Au nanocages for a broad range of theranostic applications. First, we describe their use as tracers for tracking by multiphoton luminescence. Gold nanocages can also serve as contrast agents for photoacoustic (PA) and mutimodal (PA/fluorescence) imaging. In addition, these nanostructures can be used as photothermal agents for the selective destruction of cancerous or diseased tissue. Finally, Au nanocages can serve as drug delivery vehicles for controlled and localized release in response to external stimuli such as NIR radiation or high-intensity focused ultrasound (HIFU).     

Evaluation of the Possibility of using Diatomite Natural Mineral as a Composite Agent in Acrylic Coating

In the present study the possibility of the commercially available acryl and diatomite earth (DE) mineral as a composite coating for corrosion protection of Mg alloys has been evaluated. The acrylic coating is used as a top coating in a wide field of applications like automotive, aerospace, medicine and electronics where it shows beneficial properties. Diatomite-dispersed acrylic paint was applied over the substrate by conventional spray technique with an air pressure of 3 kg cm^?2. Firstly the acryl was mixed with hardener and then the DE was added to the mixture. Four types of coating with 0, 2, 4, 8 g/L DE have been prepared. The results show that adding up to 4 g/L of the DE improved the corrosion resistance and produced a coating with acceptable surface roughness.