Synthesis and Characterization of Amorphous Si2N2O

Amorphous silicon oxynitride powder was synthesized by nitridation of high-purity silica in ammonia at 1120°C. The resulting material was X-ray amorphous, and its chemical characteristics were determined by X-ray photoelectron spectroscopy (XPS) and ²⁹Si nuclear magnetic resonance (NMR). The XPS analysis showed a shift to lower binding energies for the Si₂ p peak with increasing nitrogen content. Upon initial nitridation, the full width at half maximum (FWHM) of the Si₂ p peak increased, but decreased again at higher nitrogen contents, thus showing the formation of a silicon oxynitride phase with a single or small range of composition. The ²⁹Si NMR analysis showed the formation of (amorphous) Si₃N₄ (Si–N₄) and possibly two oxynitride phases (Si–N₃O, Si–N₂O₂). It is concluded that while XPS, FT-IR, and nitrogen analysis may show the formation of an homogeneous, amorphous silicon oxynitride (Si₂N₂O) phase, the formation of phase–pure, amorphous Si₂N₂O is extremely difficult via this route.     

Note: flowing ion population from a resonance cavity source

The experimental low energy plasma for hemispherical analyzers nominal testing thermal plasma facility of Dartmouth College uses a microwave plasma source which generates an ionosphere-like plasma through a two-step process. The plasma is initially generated inside a cylindrical, insulated, resonance cavity. This initial plasma must pass through a sheath in order to enter the main experimental region. This process imparts a significant flow velocity to the ions which has been neglected in previous analysis of this plasma source. We predict the flow energy of the ions to be between 12-15 eV depending on conservation laws and show agreement with experimental results.     

Enhanced Auditory Displays for Discriminating Landmines from Clutter Using Electromagnetic Induction Sensors

Landmine detection is primarily performed using electromagnetic induction (EMI) sensors. These sensors detect the presence of metal and convey the information to the sensor operators via an audio signal. Reduction of false alarms from objects that contain metal but are not landmines, i.e. discrimination, is a challenging problem. Recent work on automated algorithms has shown promise towards reducing false alarm rates of EMI sensors. In this study, the audio signal was modified to encode the presence of metal as well as information regarding mine/non-mine belief in order to determine whether the additional information enabled operators to better discriminate mines from clutter. Using data collected from real landmines, we experimentally investigated which perceptual dimensions most effectively convey different aspects of the information contained in the sensor response to a listener. Results indicated that the presence of metal (detection) could be coded in the fundamental frequency of the audio signal, and that mine/non-mine belief (discrimination), determined using an automated algorithm, could be coded in a separate audio dimension. Operators performed better with this audio coding scheme than one where only metal content information was presented via the fundamental frequency of the audio signal.     

Application of the Cytosensor microphysiometer to drug discovery

The Cytosensor microphysiometer uses silicon chip technology to correlate changes in extracellular acidification rates with quantitative changes in cellular metabolism in response to ligand binding to surface receptors. This functional measure of physiology makes the Cytosensor a valuable tool in drug discovery research by allowing application of the instrument to screening of prospective pharmacologically active agents, characterizations of dose responses and structure-activity relationships, and investigation of mechanisms of action.     

Specificity is complex and time consuming: mutual exclusivity in tyrosine kinase-mediated signaling

Most fundamental cellular processes are transduced through tyrosine kinase (TK)-mediated pathways. For transduction without corruption, the protein-protein interactions involved have to be mutually exclusive. Many of these proteins bind via homologous domains whose binding characteristics suggest that their innate specificity is not sufficiently high to account for the integrity of signal transduction. Stimulation of TK-mediated signals is often accompanied by recruitment of a precise, multimolecular protein complex that is itself capable of imposing specificity. Furthermore, this complex provides protection against phosphatase activity, controlling the longevity of the active signaling complex, and thus influencing outcomes in subsequent downstream events.     

Concern about weight gain associated with quitting smoking: Prevalence and association with outcome in a sample of young female smokers.

This study investigated the relationship between weight gain concern and outcomes of a large-scale smoking cessation study among 506 young female smokers attending Planned Parenthood clinics. Results of this prospective study did not support the clinical importance of weight gain concerns. Using an index of weight concern that was predictive in previous research, baseline weight concern was unrelated to smoking cessation efforts, whether participants made a quit attempt, reduced the number of cigarettes they smoked, or reported a change in self-efficacy for stopping smoking. Both the overall level of concern expressed in this sample of predominantly White young women and the lack of relationship between weight gain concern and smoking cessation outcomes suggest that weight gain concern may not be a critical factor for cessation programs targeting similar female smokers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the psychometric principles of affect.

D. Watson and L. A. Clark (see record 1997-03581-003) announced "two fundamental psychometric principles" (p. 282) of affect: The positive correlation between affects with the same valence tends to be substantial, whereas the negative correlation between affects with opposite valence tends to be weak. These allegedly robust empirical generalizations underlie various conceptual models of affect (such as those that posit an independence between positive and negative affect) and various scales of affect. The authors offer an alternative analysis: The correlation between two affects is a function of the angle between them within a circular ordering. Two data sets were reanalyzed and showed predicted exceptions to Watson and Clark's principles: same-valenced pairs with weak correlations and oppositely valenced pairs with substantial correlations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Carotenoid content and flesh color of selected banana cultivars growing in Australia

BACKGROUND: The problems of vitamin A deficiency and chronic diseases have emerged in recent years in some countries in the Micronesian region. These problems are associated with the dietary shift towards imported processed foods and lifestyle changes. Research in the Federated States of Micronesia indicates that yellow- and orange-fleshed banana cultivars contain significant levels of provitamin A carotenoids. OBJECTIVE: To identify further banana cultivars that may be promoted to alleviate vitamin A deficiency among children and women and chronic disease problems among adults. METHODS: Ripe fruit of banana cultivars growing in Australia (sourced mostly from a field research collection) were assessed for carotenoid content and flesh color. Ten cultivars with yellow or yellow/orange flesh color (including common cultivars of Southeast Asia and the Pacific Islands) were selected and compared with two cream-fleshed cultivars, including Williams, of the Cavendish group, the most commonly marketed banana worldwide. Carotenoid content was analyzed by high-performance liquid chromatography (HPLC). Flesh color was analyzed by HunterLab colorimetry. RESULTS: The yellow/orange-fleshed Asupina (a Fe'i banana) contained the highest level (1,412 microg/100 g) of trans beta-carotene, the most important provitamin A carotenoid, a level more than 20 times higher than that of Williams. All 10 yellow or yellow/orange-fleshed cultivars (Asupina, Kirkirnan, Pisang Raja, Horn Plantain, Pacific Plantain, Kluai Khai Bonng, Wain, Red Dacca, Lakatan, and Sucrier) had significant carotenoid levels, potentially meeting half or all of the estimated vitamin A requirements for a nonpregnant, nonlactating adult woman within normal consumption patterns. All were acceptable for taste and other attributes. The cream-fleshed cultivars had minimal carotenoid levels. There was a positive significant correlation between carotenoid content and deeper yellow/orange coloration indicators. CONCLUSIONS: These yellow- or yellow/orange-fleshed carotenoid-rich banana cultivars should be considered for promotion in order to alleviate vitamin A deficiency and chronic disease in susceptible target communities and to provide variety and enjoyment as exotic fruits in both developing and industrialized countries.