Design of LTCC with High Thermal Expansion

New applications of low-temperature co-fired ceramics (LTCC), such as pressure sensors or integrated functional layers, require materials that possess higher coefficients of thermal expansion (CTE). To fabricate LTCC with elevated CTE, two methods of material design are examined: firstly, glass ceramic composites (GCC), which consist of >50 vol% glass in the starting powder, and, secondly, glass-bonded ceramics (GBC), where glass is added as a sintering aid only. The CTE of GBC is mainly determined by the crystalline component. For GCC, the CTE can be well predicted, if CTE and elastic data of each phase in the microstructure are known. A nonlinear characteristic of the CTE versus phase composition was found with increasing E _crystals/ E _glass ratio and absolute CTE difference between the components. The glass composition and glass amount can be used to compensate the fixed properties of a crystalline material in a desired way. However, because the CTE and permittivity of a glass cannot be chosen independently, an optimum glass composition has to be found. For a given LTCC, it is possible to control the devitrification by shifting the glass composition. In this way, the resulting CTE values can be predicted more exactly and tailoring becomes possible. Different LTCC materials, based on the crystalline compounds Ba(La,Nd)₂Ti₄O₁₂, ZrO₂ (Y-TZP), SiO₂ (quartz), and specially developed glasses, possessing an elevated CTE of around 10 × 10⁻⁶ K⁻¹ while showing permittivity ɛ_r between 6 and 63, are introduced.     

CARIN theory reanalysis reanalyzed: A comment on Maguire, Devereux, Costello, and Cater (2007).

P. Maguire, B. Devereux, F. Costello, and A. Cater (see record 2007-08734-012) discussed the Gagné and Shoben (1997) CARIN theory of conceptual combination and, after presenting a sample drawn from the British National Corpus and comparing the two corpora, concluded that the Gagné and Shoben corpus is too small and unrepresentative. They then discussed the mathematical model presented by Gagné and Shoben and claimed that the model does not incorporate relational competition. In this article, the authors present critical aspects of the mathematical model not considered by Maguire et al. and show that the mathematical instantiation of CARIN presented by Gagń and Shoben is, in fact, very sensitive to the number of strong competing relations. The authors then present some new comparisons between the corpora, showing that they correspond surprisingly well. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Improving TCP performance over wireless networks at the link layer

We present the transport unaware link improvement protocol (TULIP), which dramatically improves the performance of TCP over lossy wireless links, without competing with or modifying the transport- or network-layer protocols. TULIP is tailored for the half-duplex radio links available with today's commercial radios and provides a MAC acceleration feature applicable to collision-avoidance MAC protocols (e.g., IEEE 802.11) to improve throughput. TULIP's timers rely on a maximum propagation delay over the link, rather than performing a round-trip time estimate of the channel delay. The protocol does not require a base station and keeps no TCP state. TULIP is exceptionally robust when bit error rates are high; it maintains high goodput, i.e., only those packets which are in fact dropped on the wireless link are retransmitted and then only when necessary. The performance of TULIP is compared against the performance of the Snoop protocol (a TCP-aware approach) and TCP without link-level retransmission support. The results of simulation experiments using the actual code of the Snoop protocol show that TULIP achieves higher throughput, lower packet delay, and smaller delay variance. This revised version was published online in June 2006 with corrections to the Cover Date.     

A two-platform task reveals a deficit in the ability of rats to return to the start location in the water maze.

The ability of rats to return to the start location was examined with a 4-arm radial water maze. The task required rats to find 2 hidden platforms in sequence. Rats were released from 1 of 3 arms and there was a platform located in the fourth arm. Once a rat found this platform, a 2nd platform was raised in another location, which was either the start location, for 1 group, or another fixed location, for a control group. Across 3 experiments, all rats learned the location of the 1st fixed platform in 80 to 120 trials. However, rats had difficulty finding a 2nd platform if it was at the start location. Control groups revealed that rats could learn 2 platform locations and that the difficulty in learning to return to the start location did not seem to be attributable to its aversive nature. In separate groups, exposure to the start location was increased by starting the rats from an initially stable platform. Rats still did not readily learn to return to the start location. The authors suggest that start location, when varied, cannot readily be used to define the location of a hidden platform. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Global Perspectives on Fetal Alcohol Syndrome: Assessing Practices, Policies, and Campaigns in Four English-Speaking Countries.

Maternal alcohol consumption during pregnancy places the fetus at risk for a number of neurological abnormalities and functional impairments. These deficits are 100% preventable by abstaining from alcohol use during pregnancy. Nevertheless, the worldwide prevalence of Fetal Alcohol Syndrome (FAS), the most severe outcome of prenatal alcohol consumption, is estimated at 0.97 cases per 1,000 live births (see May & Gossage, 2001). This paper examines awareness of the problem in Canada, the United States, the United Kingdom, and Australia along three dimensions: 1) the relationship between alcohol consumption rates and the incidence of FAS; 2) government action and policy creation; and 3) prevention/intervention initiatives and educational efforts. The extent of knowledge within each country affects, and is affected by, the level of research activity, the emphasis on policy creation, and the initiatives that drive educational efforts. At present, Canada and the U.S. have the highest levels of activity and a clear recognition of the problem. Activity in the U.K. and Australia is at the grass-roots level, although some promising movements toward greater public and professional awareness have begun. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reliability of adult retrospective recall of lifetime tobacco use.

Retrospective assessment of tobacco use underlies much of the data collected in epidemiological and genetic epidemiological research. Although individuals are asked to report lifetime tobacco use for periods spanning months to decades, the test-retest reliability intervals of the instruments often span only a few weeks to several months. The present analyses examined the test-retest reliability of retrospective tobacco use measures, including details of first use, circumstances of first use, and initial subjective reactions. The questions were part of the Lifetime Tobacco Use Questionnaire (LTUQ), a Web-based questionnaire designed to assess use of most forms of tobacco or nicotine retrospectively across the lifespan. A convenience sample of 236 men and women with history of tobacco use (Time 1 mean age, 44.9 years; 74.2% females; 75.1% regular monthly tobacco use) responded verifiably to invitations to self-administer the LTUQ two times, 2 years apart. Test-retest reliability analyses reflected high reliability for salient tobacco-use questions. Acceptable levels of reliability were observed for initial subjective reactions to smoking, if the scaled response options were dichotomized. Few differences in the reliability of recall were apparent between sexes and between age groups. These results indicate that recall of important tobacco use information can form a reliable basis for research.     

What Makes a Good City in Pre-schoolers' Eyes? Findings from Participatory Planning Projects in Australia and New Zealand

Pre-schooler's voices are absent in urban planning and design. With the possible exception of playgrounds, there is limited knowledge about their experiences in and expectations for urban environments. This paper discusses pre-schoolers' aspirations and desires for aesthetic and accessible green spaces as well as social and physical connectedness. Although this age range has so far been limited in its ability to inform policy and decision-makers, it is argued that pre-schoolers have the capacity and capability of making valuable contributions to design. In the eyes of pre-schoolers, creating a good city means to live in a safe place full of diverse destinations in which they can become streetwise and socialize as part of society.     

Age and Mating Status Do Not Affect Transcript Levels of Odorant Receptor Genes in Male Antennae of Heliothis virescens and Heliothis subflexa

In biological systems, it is expected that gene expression levels generally will correlate with temporally varying physiological and biological needs, and that gene expression levels could regulate biological capabilities. In moth species, male response to female sex pheromones often is affected by moth age and mating status. Odorant receptors (ORs) expressed in neurons within male antennae are critical for detecting the female pheromones. Therefore, we hypothesized that the expression level of these receptor proteins would be affected by age and mating status of male moths. We examined expression levels of two OR genes that are preferentially expressed in the male antennae of Heliothis virescens (HvOR13 and HvOR15) and Heliothis subflexa (HsOR13 and HsOR15). Antennae were dissected from virgin males at 2 h, 1 d, 2 d, 4 d, and 8 d. We also dissected antennae from 4-d-old mated males. We found that age had no effect on expression levels of either OR in either species, except for a small difference in HsOR15 expression between 2 h and 8-d-old virgin males. Furthermore, we found no effect of mating status on expression level of these ORs in either species. We discuss these findings in relationship to studies of age and mating status effects on male electrophysiological and behavioral response to female pheromones, and contrast our results to studies on the effects of age and mating status on gene expression of pheromone receptor proteins and pheromone binding proteins in other moths.