Structural Studies of (Ca,Sr)F2 Single Crystals with Raman and NMR Spectroscopies

Single crystal CaF₂ is the material of choice for optics in the vacuum UV, due in part to its high transmission at these wavelengths. Unfortunately, as the wavelengths decrease, intrinsic birefringence (also referred to as spatial dispersion) can become larger than the target birefringence for precision optics at 157 nm, even for a cubic material such as CaF₂. One elegant solution to this problem is to capitalize on opposite signs for this intrinsic birefringence, such as mixing SrF₂ or BaF₂ with CaF₂. If the proper fluorides are mixed with the correct concentration, the intrinsic birefringence of the mixed single crystals can be minimized. It is also important that the resulting mixed single crystal maintain the high symmetry of CaF₂, which requires that the cations mix randomly in the CaF₂ structure. We show through Raman and NMR spectroscopic studies that this random mixing of cations can be achieved for mixed (Ca,Sr)F₂ single crystals. A single Raman band is observed for all mixed crystals, which changes in both position and width upon addition of SrF₂ to CaF₂. ¹⁹F NMR spectra also reflect a random distribution of cations around the different fluorine environments in the mixed crystals.     

Blind source separation of internal combustion engine piston slap from other measured vibration signals

Internal combustion engines have several vibration sources, such as combustion, fuel injection, piston slap and valve operation. For machine condition monitoring or design improvement purposes, it is necessary to separate the vibration signals caused by different sources and then analyse each of them individually. However, traditional frequency analysis techniques are not very useful due to overlap of the different sources over a wide frequency range. This paper attempts to separate the vibration sources, especially piston slap, by using blind source separation techniques with the intention of revealing the potential of the new technique for solving mechanical vibration problems. The BSS method and the Blind least mean square algorithm using Gray's variable norm as a measure of non-Gaussianity of the sources is briefly described and separation results for both simulated and measured data are presented and discussed.     

Comparing six video chat tools: A critical evaluation by language teachers

This article presents a critical comparison of the usefulness and practicality of six CMC video chat tools (CUworld, ICQ, MSN Messenger, Paltalk, Skype, and Yahoo Messenger) from the perspective of language teaching professionals. This comparison is based on the results of a semester-long project between graduate students at an American university and their counterparts at a university in Turkey. The language teachers were asked to pair up with a partner in the collaborating university to test and then evaluate each of these tools via video chat tool evaluation sheets. They also completed an overall evaluation sheet commenting on CMC tools in general and ranking the video chat tools in terms of their potential as language teaching tools and their usability for personal communication purposes. The qualitative and quantitative analyses of the evaluation sheets indicate a clear preference for MSN Messenger and Skype while placing CUworld and Paltalk at the bottom of the list. The article also provides pedagogical implications and applications for using tools for language teaching purposes.     

Self-attention and reported symptoms: Implications for forensic assessment.

Does patient self-attention to physical and psychological symptoms compared to self-distraction result in different clinical conclusions in forensic contexts? Participants in 2 studies were instructed either to attend carefully to somatic symptoms and sensations (attention instructions), to tally how many questionnaire items were related to physical versus emotional symptoms (distraction instructions), or received no attentional instructions (controls). The principal findings were that physical symptoms and reports of anxiety and depression were greater after attention instructions than after distraction instructions. Insofar as assessment contexts produce differential attention to self, examiners are advised to use caution in drawing conclusions regarding accuracy of self-reported symptoms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Design of the PID Evaluation and Clinical Health (PEACH) Study

This paper describes the PID Evaluation and Clinical Health Study (PEACH), a multicenter, randomized clinical trial designed to compare treatment with outpatient and inpatient antimicrobial regimens among women with pelvic inflammatory disease (PID). PEACH is the first trial to evaluate the effectiveness and cost-effectiveness of currently recommended antibiotic combinations in preventing infertility, ectopic pregnancy, chronic pelvic pain, recurrent PID, and other health outcomes. It is also the largest prospective study of PID ever conducted in North America. We describe the PEACH study's specific aims, study organization, patient selection criteria, conditions for exclusion, data collected upon entry, randomization and treatment, adherence measures, follow-up activities, quality-of-life measures, outcomes, and statistical analyses. In the first 11 months of enrollment (March 1996-January 1997), 312 women were randomized. Of eligible women, 59% consented to enroll. Participating women are primarily black (72%) and young (mean age 24 years). After a median of 5.5 months of follow-up, we were in contact with 95% of study participants. The PEACH study will provide a rationale for selecting between inpatient and outpatient antibiotic treatment, the two most common treatment strategies, for PID.     

Biliary glycoprotein (CD66a), a cell adhesion molecule of the immunoglobulin superfamily, on human lymphocytes: structure, expression and involvement in T cell activation

The biliary glycoproteins (BGP or CD66a), a group of different splice variants of a single gene, are members of the carcinoembryonic antigen family and the immunoglobulin superfamily. Recently, we detected CD66a on IL-2 activated lymphocytes. In this study we characterized the structure and the expression pattern of BGP on human lymphocytes and investigated its role in T cell activation. Lymphocytes express 2 of the 13 known splice variants, i.e. BGPa and BGPb, which are glycosylated in a lymphocyte-specific manner. Both BGPa and BGPb have the long cytoplasmic tail, which contains two immunoreceptor tyrosine-based inhibitory motif (ITIM)-like motifs, but differ in their extracellular region containing 4 and 3 immunoglobulin-like domains, respectively. On PBL BGP is expressed in small amounts only on B cells and Th cells. Stimulation with IL-2 leads to a strong up-regulation of BGP by these cells, and induces de novo BGP expression on gammabeta T cells, CD8+ and CD56+ cells, but not on CD16+ lymphocytes. This up-regulation of BGP seems to be part of the physiological process of T cell activation, since stimulation with anti-CD3 mAb is sufficient to induce BGP up-regulation. Based on the presence of the two ITIM-like motifs, one may expect that BGP inhibits T cell activation, but surprisingly, engagement of BGP enhances the proliferation of anti-CD3-stimulated T cells.     

Advantages of Low Partial Pressure of Oxygen Processing of Alkali Niobate: NaNbO3

This work focused on the processing of low oxygen partial pressure (low‐pO₂) calcination and sintering with respect to NaNbO₃ (NN) of one key member in ferroelectric (Na,K)NbO₃. The high‐density NN ceramics were successfully prepared without any sintering additives using the low‐pO₂ process. Comparing conventional air process, the low‐pO₂ calcined NN powders showed lower defect concentration and higher densification. The low‐pO₂ sintered NN ceramics had dielectric constant and dielectric loss performance at high temperatures. Furthermore, the low‐pO₂ sintered NN ceramics indicated ferroelectric behavior, and both maximum polarization and strain improved to two to three times that of conventional air‐sintered NN ceramics. From this relatively simple compound, NN, the advantage of low‐pO₂ is unambiguously demonstrated and points to its consideration. It is hypotheses as a kinetically controlled process that limits the volatility under low‐pO₂ condition.     

Effect of Ferroelectric Polarization on Ionic Transport and Resistance Degradation in BaTiO3 by Phase‐Field Approach

We proposed a model to study the resistance degradation behavior of ferroelectric oxides in the presence of ferroelectric spontaneous polarization by combining the phase‐field model of ferroelectric domains and nonlinear diffusion equations for ionic/electronic transport. We took into account the nonperiodic boundary conditions for solving the electrochemical transport equations and Ginzburg–Landau equations using the Chebyshev collocation algorithm. We considered a single domain structure relative to a thin film BaTiO₃ single crystal orientated to the normal of the electrode plates (Ni) in a single parallel plate capacitor configuration. The capacitor was subjected to a dc bias of 0.5 V either along the polarization direction or opposite to the polarization direction at 25°C. It is shown that the polarization bound charges at the metal/ferroelectric interface play an important role in charge carrier transport and leakage current evolution in BaTiO₃ capacitor.     

Mixture-Amount Design and Response Surface Modeling to Assess the Effects of Flavonoids and Phenolic Acids on Developmental Performance of Anastrepha ludens

Host plant resistance to insect attack and expansion of insect pests to novel hosts may to be modulated by phenolic compounds in host plants. Many studies have evaluated the role of phenolics in host plant resistance and the effect of phenolics on herbivore performance, but few studies have tested the joint effect of several compounds. Here, we used mixture-amount experimental design and response surface modeling to study the effects of a variety of phenolic compounds on the development and survival of Mexican fruit fly (Anastrepha ludens [Loew]), a notorious polyphagous pest of fruit crops that is likely to expand its distribution range under climate change scenarios. (+)- Catechin, phloridzin, rutin, chlorogenic acid, and p-coumaric acid were added individually or in mixtures at different concentrations to a laboratory diet used to rear individuals of A. ludens. No effect was observed with any mixture or concentration on percent pupation, pupal weight, adult emergence, or survival from neonate larvae to adults. Larval weight, larval and pupal developmental time, and the prevalence of adult deformities were affected by particular mixtures and concentrations of the compounds tested. We suggest that some combinations/concentrations of phenolic compounds could contribute to the management of A. ludens. We also highlight the importance of testing mixtures of plant secondary compounds when exploring their effects upon insect herbivore performance, and we show that mixture-amount design is a useful tool for this type of experiments.