Interval timing accuracy and scalar timing in C57BL/6 mice.

In many species, interval timing behavior is accurate—appropriate estimated durations—and scalar—errors vary linearly with estimated durations. Whereas accuracy has been previously examined, scalar timing has not been clearly demonstrated in house mice (Mus musculus), raising concerns about mouse models of human disease. The authors estimated timing accuracy and precision in C57BL/6 mice, the most used background strain for genetic models of human disease, in a peak-interval procedure with multiple intervals. Both when timing 2 intervals (Experiment 1) or 3 intervals (Experiment 2), C57BL/6 mice demonstrated varying degrees of timing accuracy. An important finding was that, both at the individual and group levels, their precision varied linearly with the subjective estimated duration. Further evidence for scalar timing was obtained using an intraclass correlation statistic. This is the first report of consistent, reliable scalar timing in a sizable sample of house mice, thus validating the peak-interval procedure as a valuable technique, the intraclass correlation statistic as a powerful test of the scalar property, and the C57BL/6 strain as a suitable background for behavioral investigations of genetically engineered mice modeling disorders of interval timing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Essais saoudiens sur les ciments importés

Au fur et à mesure que le développement s'accélère en Arabie saoudite, les matériaux importés deviennent de plus en plus nombreux et entrent en concurrence les uns avec les autres. Le Materials Testing Laboratory de Riyad a procédé, il ny a pas très longtemps, à une étude comparative d'échantillons de ciments importés et de ciments fabriqués dans le pays. S'ils concernent avant tout les chimistes du ciment, les résultats n'en présentent pas moins un intérêt plus général.     

Single-Row Transformation of Complete Graphs

A complete graph is a fully-connected graph where every node is adjacent to all other nodes in the graph. Very often, many applications in science and engineering are reducible to this type of graph. Hence, a simplified form of a complete graph contributes in providing the solutions to these problems. In this paper, we present a technique for transforming a complete graph into a single-row routing problem. Single-row routing is a classical technique in the VLSI design that is known to be NP-complete. We solved this problem earlier using a method called ESSR, and, the same technique is applied to the present work to transform a complete graph into its single-row routing representation. A parallel computing model is proposed which contributes in making the problem modular and scalable. We also discuss the application of this work on the channel assignment problem in the wireless cellular telephone networks.     

Polychromatic reflectance and transmittance of a slab with a randomly rough boundary

We investigated four different approximation models for describing the polychromatic reflectance and transmittance of a slab with a randomly rough boundary while taking into account the coherent and the incoherent scattering of the rough boundary. Comparisons with experiments (an etched-silicon wafer) show that approximation models that apply a two-scale roughness to the randomly rough boundary and that take into account the coherent and the incoherent scattering yield better agreement and extend the range of validity of the approximation to shorter wavelengths.     

Experimental study of inward freezing in circular and square pipes

This paper describes the results of an experimental study of the inward freezing of water in tubes of circular and square geometries. The temperature-time history is recorded using thermocouples, from which the progress of the freezing front is deduced. The results obtained pertain to the conditions of water not initially at freezing temperature, the outside surface temperature of the tube varying with time. Since the available theories assume liquid to be initially at freezing temperature and a constant sub-freezing temperature at the outside surface, a rigorous comparison is not possible. In order to make some sort of comparison, the sensible heat of water has been incorporated into the latent heat while the actual surface temperature variation has been replaced by its time-average value. Despite these approximations, the experimental results are in reasonable agreement with the theory.     

Data Converter for Multistandard Mobile Phones

This paper describes an analog to digital converter (ADC) for mobile communication systems using a direct down conversion architecture. The ADC can be programmed to meet the requirements of different communication standards, including GSM (Global System for Mobile communication) and WCDMA (Wideband Code Division Multiple Access). The ADC is realized with a pipeline ADC architecture for WCDMA and a Sigma-Delta architecture for GSM. In order to have an optimized area and power consumption, the basic building blocks (opamps) of the converters are shared between the two converter architectures. The entire ADC consumes about 5.5 mW and occupies an active area of about 0.36 mm². A test circuit has been developed and fabricated and measurements show that both the required programmability and the required performance can be obtained using the proposed configurations.     

SIVA: A System for Coverage-Directed State Space Search

We introduce SImulation Verification with Augmentation (SIVA), a tool for coverage-directed state space search on digital hardware designs. SIVA tightly integrates simulation with symbolic techniques for efficient state space search. Specifically, the core algorithm uses a combination of ATPG and BDDs to generate directed input vectors, i.e., inputs which cover behavior not excited by simulation. We also present approaches to automatically generate lighthouses that guide the search towards hard-to-reach coverage goals. Experiments demonstrate that our approach is capable of achieving significantly greater coverage than either simulation or symbolic techniques in isolation.     

Successful Delivery of Public-Private Partnerships for Infrastructure Development

Two common approaches have been used by governments for the implementation of public-private partnerships (PPPs): a finance-based approach that aims to use private financing to satisfy infrastructure needs, and a service-based approach that aims to optimize the time and cost efficiencies in service delivery. The implementation of PPPs, however, may suffer from legal, political, and cultural impediments. In the United States, the federal government enabled a number of acts to ease the impediments and promote PPPs for infrastructure development. Based on a detailed analysis of PPPs in the United Kingdom and British Columbia, Canada, this paper describes principles that would characterize the implementation of PPPs at the program level (e.g., whether the implementation is successful). The principles pertain to the: availability of a PPP legal framework and implementation units; perception of the private finance objectives, risk allocation consequences, and value-for-money objectives; maintenance of PPPs process transparency; standardization of procedures; and use of performance specifications. Guidelines for successful implementation are explained and discussed in the context of the United States PPPs experience and impediments.     

Exciton-induced degradation of organic/electrode interfaces in ultraviolet organic photodetectors

We study the degradation mechanisms of ultraviolet (UV) organic photodetectors (OPDs). Contrary to expectations, we determine that the bulk of the organic layers in UV OPDs is stable under prolonged UV irradiation, showing no detectable changes in photophysical characteristics such as photoluminescence yield and exciton lifetime and thus not contributing to the observed degradation behavior of UV OPDs. However, the results show that the organic/electrode interfaces in UV OPDs, including indium tin oxide (ITO)/organic and organic/metal ones, are susceptible to UV irradiation, leading to a deterioration in both charge injection and extraction across the interfaces. The degradation of the organic/electrode interfaces in UV OPDs is essentially induced by UV-generated excitons in their vicinity and may be responsible for nearly 100% of the photo-current loss of UV OPDs. Approaches for improving the photo-stability of organic/electrode interfaces, and thus the lifetime of UV OPDs, are also investigated. We demonstrate that the use of thin (∼0.5 nm) interfacial layers such as lithium acetylacetonate at organic/metal interfaces can significantly reduce the interfacial degradation, and the use of appropriate hole transport materials such as N,N′-bis (naphthalen-1-yl)-N,N′-bis(phenyl) benzidine at ITO/organic interfaces can greatly improve the interfacial photo-stability.