Neurocognitive signs in prodromal Huntington disease.

Objective: PREDICT-HD is a large-scale international study of people with the Huntington disease (HD) CAG-repeat expansion who are not yet diagnosed with HD. The objective of this study was to determine the stage in the HD prodrome at which cognitive differences from CAG-normal controls can be reliably detected. Method: For each of 738 HD CAG-expanded participants, we computed estimated years to clinical diagnosis and probability of diagnosis in 5 years based on age and CAG-repeat expansion number (Langbehn, Brinkman, Falush, Paulsen, & Hayden, 2004). We then stratified the sample into groups: NEAR, estimated to be ≤9 years; MID, between 9 and 15 years; and FAR, ≥15 years. The control sample included 168 CAG-normal participants. Nineteen cognitive tasks were used to assess attention, working memory, psychomotor functions, episodic memory, language, recognition of facial emotion, sensory–perceptual functions, and executive functions. Results: Compared with the controls, the NEAR group showed significantly poorer performance on nearly all of the cognitive tests and the MID group on about half of the cognitive tests (p = .05, Cohen's d NEAR as large as ?1.17, MID as large as ?0.61). One test even revealed significantly poorer performance in the FAR group (Cohen's d = ?0.26). Individual tasks accounted for 0.2% to 9.7% of the variance in estimated proximity to diagnosis. Overall, the cognitive battery accounted for 34% of the variance; in comparison, the Unified Huntington's Disease Rating Scale motor score accounted for 11.7%. Conclusions: Neurocognitive tests are robust clinical indicators of the disease process prior to reaching criteria for motor diagnosis of HD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Vaccines against endogenous hormones: a possible future tool in animal production

Vaccines have been widely used by the livestock industry to control and prevent disease. New technologies now permit development of vaccines against hormones that control reproduction, growth, and lactation in domestic farm animals. Results of research projects studying passive and active immunization against such hormones as estrogen, testosterone, LH, FSH, and somatotropin have demonstrated that reproductive efficiencies and growth can be altered through vaccination. Although immunizations against most of the hormones studied have proven effective in most cases, there remain problems related to longevity, consistency, and efficiency of response both within and between animals. When these areas have been clearly defined for individual hormones, standardized immunization regimens can be developed that will optimize antibody production in the animal, thus providing the animal agriculture industry with a powerful and profitable production tool.     

QoS control versus generous dimensioning

As the world of telecommunications embraces IP as the route to truly converged networks there are, for pioneering national telecommunications operators, difficult engineering requirements to address — in particular, how to deliver high-quality session-based services over a connectionless infrastructure. The falling price of commodity bit transport leads some to suggest that simply providing high levels of capacity will be enough to provide effective quality in the ‘new wave’ networks, and that sophisticated approaches, such as explicit bandwidth reservation, are an expensive luxury. We discuss the implications of operating a network under the two very different paradigms of QoS control (bandwidth reservation under connection control) and generous dimensioning, focusing at first on a pure PSTN replacement, before considering the implications for a true, converged multiservice platform. We conclude that these two approaches give rise to different services. In an increasingly competitive world we might choose either approach for different commercial reasons, but we should not be misled into believing that generous dimensioning gives us the same service as QoS control.     

Low‐Temperature Superionic Conductivity in Strained Yttria‐Stabilized Zirconia

Very high lateral ionic conductivities in epitaxial cubic yttria‐stabilized zirconia (YSZ) synthesized on single‐crystal SrTiO₃ and MgO substrates by reactive direct current magnetron sputtering are reported. Superionic conductivities (i.e., ionic conductivities of the order ～1 Ω^?1cm^?1) are observed at 500 °C for 58‐nm‐thick films on MgO. The results indicate a superposition of two parallel contributions – one due to bulk conductivity and one attributable to conduction along the film–substrate interface. Interfacial effects dominate the conductivity at low temperatures (<350 °C), showing more than three orders of magnitude enhancement compared to bulk YSZ. At higher temperatures, a more bulk‐like conductivity is observed. The films have a negligible grain‐boundary network, thus ruling out grain boundaries as a pathway for ionic conduction. The observed enhancement in lateral ionic conductivity is caused by a combination of misfit dislocation density and elastic strain in the interface. These very high ionic conductivities in the temperature range 150–500 °C are of great fundamental importance but may also be technologically relevant for low‐temperature applications.     

Study of Morphological Defects on Dual-Band HgCdTe on CdZnTe

HgCdTe dual-band epitaxial layers on lattice-matched CdZnTe substrates often have morphological defects. These defects, unlike normal void and microvoid defects, do not contain a polycrystalline core and, therefore, do not offer a good contrast for observation using optical and electron microscopes. This paper reports a way of identifying these defects by using a Nomarski optical microscopy image overlay on focused ion beam microscopy images for preparation of thin cross-sectional foils of these defects. Transmission electron microscopy was used to study the defect cross-sections to identify the origin and evolution of the morphological defects and their effect on the epitaxial layer. This paper reports cross-sectional analysis of four morphological defects of different shape and size.     

A methodology for designing,modifying, and implementing Fourier transform algorithms on various architectures

Fourier transform algorithms are described using tensor (Kronecker) products and an associated class of permutations. Algebraic properties of tensor products and the related permutations are used to derive variants of the Cooley-Tukey fast Fourier transform algorithm. These algorithms can be implemented by translating tensor products and permutations to programming constructs. An implementation can be matched to a specific computer architecture by selecting the appropriate variant. This methodology is carried out for the Cray X-MP and the AT&T DSP32.This work was performed at the Center for Large Scale Computation, Suite 400, 25 West 43rd Street, New York, New York 10036, USA, and was supported by a grant from DARPA/ACMP.     

Monolithic two-dimensional GaAs/AIGaAs laser arrays fabricated by chlorine lon-beam-assisted micromachining

Chlorine ion-beam-assisted etching (IBAE) has been used to micromachine laser facets and deflecting mirrors for monolithic two-dimensional GaAs/AIGaAs laser arrays. Three laser cavity/deflector designs have been successfully implemented. The first utilizes a parabolic deflecting mirror to directly focus the laser radiation; the second consists of a folded cavity with a vertical facet, a top surface facet, and an internal 45° reflector; and the third has a folded cavity with an internal Al_0.2Ga_0.8As/Al_0.8Ga_0.2As dielectric mirror stack and a top surface facet formed in a single etch step with two internal 45° reflectors. The parabolic deflecting mirrors are currently modeled forf- 0.8 collection efficiency, making the first design attractive in incoherent arrays for high-power applications such as pumping Nd:YAG lasers. The other two structures are of interest for incoherent or coherent arrays used in high- and medium-power applications, since the top surface facets can easily be antireflection coated. The design with a dielectric mirror stack is particularly simple to fabricate.     

Developing a conductive oxygen barrier for ferroelectric integration

For high-density FeRAM memories, the 1T–1C architecture has been proposed. In this scheme, the ferrocapacitor (FeCAP), a metal\ferroelectric film\metal-like sandwich, is placed directly on top of polysilicon or tungsten plugs contacted to the underlying CMOS technology. Our ferroelectric material of choice, SrBi₂Ta₂O₉ (SBT), requires crystallization anneals ranging from 650 to 800 °C in full oxygen. The bottom electrode (BE) needs to be conductive, as well as an oxygen barrier to protect the underlying plug from oxidation. We have developed a BE stack combination consisting of Pt/IrO₂/Ir/Ti(Al)N. Each layer plays a critical role in the performance of the barrier. Issues such as thermal expansion, stress relaxation, grain growth, and oxidation can be critical in order to have a working bottom electrode. For capacitor formation, the complete stack is etched and covered by SBT. Since all layers are in contact with SBT, it is important to understand how the ferroelectric interacts with both the individual layers and the combined structure. In this paper, we will present our understanding of the chemical reactivity between SBT and the BE stack, which has been successfully engineered to prevent oxidation of the underlying plug.