Near-field second harmonic imaging of lead zirconate titanate piezoceramic

Near-field optical microscopy has been used to image variations in local optical second harmonic generation (SHG) from the surface of lead zirconate titanate (PZT) piezoceramic. As PZT ceramic is a strongly scattering medium. SHG occurs in the thin layer near the surface of the ceramic. Thus, individual crystalline grains and grain boundaries located near the surface are the main features visible in the images. In general, this technique allows us to determine the local poling direction of individual submicrometre-sized crystalline grains of ceramic by near-field SH imaging at different angles of incidence and polarization states of the fundamental excitation light. In some cases 'hot spots' of submicrometre size showing enhanced SHG have been observed. This enhancement is believed to result from local cavity resonances.     

Monte carlo simulation of a single-molecule detection experiment

The physical and instrumental processes that occur in experiments for the detection of individual fluorescent molecules in solution are described, with emphasis on their incorporation into a quantitative Monte Carlo simulation. The simulation is applied to the conditions of a past experiment [Appl. Opt. 34, 3208 (1995)], which utilizes a sheath flow system for high detection efficiency, and it generates comparable results, while helping to identify experimental limitations. The simulation indicates that the use of low dead-time electronics and appropriate selection of experimental parameters should enable detection at more rapid rates for applications in which large numbers of molecules are to be efficiently counted.     

Lateral epitaxial overgrowth of GaN films on SiO2 areas via metalorganic vapor phase epitaxy

Lateral epitaxial growth and coalescence of GaN regions over SiO₂ masks previously deposited on GaN/AlN/6H-SiC(0001) substrates and containing 3 μm wide rectangular windows spaced 7 μm apart have been achieved. The extent and microstructural characteristics of these regions of lateral overgrowth were a complex function of stripe orientation, growth temperature, and triethylgallium (TEG) flow rate. The most successful growths were obtained from stripes oriented along 〈1 00〉 at 1100°C and a TEG flow rate of 26 μmol/min. A density of ∼10⁹ cm⁻² threading dislocations, originating from the underlying GaN/AlN interface, were contained in the GaN grown in the window regions. The overgrowth regions, by contrast, contained a very low density of dislocations. The surfaces of the coalesced layers had a terrace structure and an average root mean square roughness of 0.26 nm.     

Irritant contact stomatitis: a review of the condition

Several different types of interactions are possible between a chemical, a mixture of chemicals, and associated extrinsic factors (i.e., mechanical irritation) in the oral mucosa. These interactions can be broadly classified as irritative or allergenic in nature. In each case, the pathology usually includes mucosal inflammation. The information compiled and reviewed in this article suggests that, given the broad definition of surface lesions/mucosal abnormalities, there may be a continuum of irritation that can be termed "irritant contact stomatitis." This may be due to the fact that the mouth is lined with highly vascular mucosa that turns over rapidly compared to the skin, and may or may not be covered by keratin. Some regions in the mouth are uniquely sensitive to irritants because they can penetrate through the tissue easily. Key factors involved in the potential development of irritation are: inherent irritation potential of the agent, amount of exposure (concentration, duration, and frequency), ability to penetrate the tissue, and inherent reactivity of the subject as well as other extrinsic factors. Irritation leading to oral mucosal alterations is a common occurrence caused by a wide variety of exposures and insults to the oral cavity. Various irritants such as foods, chemicals, friction, thermal/mechanical injury, metals, spices, and oral care products have been documented to cause irritant reactions in susceptible individuals, particularly if used under exaggerated exposure conditions. It is important to note that most irritation in the oral cavity tends to reverse quickly when the causative agent is removed. Oral irritation is a commonly occurring phenomenon. Thus, it is important that the clinician be aware of the clinical manifestations and etiology of the condition.     

A five-year study of graduates' performance on NCLEX-RN

A 5-year study of graduates' performance on NCLEX-RN was conducted using data from July 1988 through February 1994. This time frame related to the "new" test plan introduced in 1988 with pass/fail results for NCLEX analysis. Using a quota sampling technique of 188 graduates, selected admission and curriculum variables and National League for Nursing (NLN) Comprehensive Achievement Test scores were studied in relationship to NCLEX-RN examination results. The strongest indicators of success were SAT verbal scores, nursing grade point average, and NLN Comprehensive Achievement Test scores. In addition, logistic regression analyses identified three nursing courses in combination with the NLN Comprehensive Achievement Test score as a strong model for prediction. Even though pass/fail data limit statistical analyses, the predictor variables were strong at P = 0.0001. These findings are consistent with prior studies.     

The Open International Soccer Database for machine learning

How well can machine learning predict the outcome of a soccer game, given the most commonly and freely available match data? To help answer this question and to facilitate machine learning research in soccer, we have developed the Open International Soccer Database. Version v1.0 of the Database contains essential information from 216,743 league soccer matches from 52 leagues in 35 countries. The earliest entries in the Database are from the year 2000, which is when football leagues generally adopted the “three points for a win” rule. To demonstrate the use of the Database for machine learning research, we organized the 2017 Soccer Prediction Challenge. One of the goals of the Challenge was to estimate where the limits of predictability lie, given the type of match data contained in the Database. Another goal of the Challenge was to pose a real-world machine learning problem with a fixed time line and a genuine prediction task: to develop a predictive model from the Database and then to predict the outcome of the 206 future soccer matches taking place from 31 March 2017 to the end of the regular season. The Open International Soccer Database is released as an open science project, providing a valuable resource for soccer analysts and a unique benchmark for advanced machine learning methods. Here, we describe the Database and the 2017 Soccer Prediction Challenge and its results.

     

Cognitive impact of traumatic events

The impact of traumatic experiences on cognitive processes, especially memory, is reviewed. The major psychological sequelae of trauma (reexperiencing, avoidance, hypervigilance) and posttraumatic stress disorder (PTSD) are noted and related to traditional views of fear conditioning. Evidence indicating enhanced memory for the gist of emotional events is reviewed as are psychological and neurophysiological mechanisms underlying this enhancement. This view is updated by introducing the distinction between explicit and implicit memory and its relevance to traumatic memory and PTSD. The central role of "the experiencing ego" in the storage and retrieval of episodic memories is postulated. This leads into discussion of dissociative experiences during traumas and the occasional amnesia for voluntary recall of the trauma accompanied by involuntary, uncontrollable flashbacks of it. The relationship of dissociative experiences to hypnotizability and to pathological reactions to traumas is discussed, although the interpretation of those correlations is questioned. The article concludes by noting that beyond conditioning of fear, traumas often violate and shake the victims' basic assumptions about the benevolence, justice, and meaningfulness of their physical and social worlds. Psychotherapy with trauma victims then needs to attend not only to extinguishing the victims' fear and feelings of extreme vulnerability, but also to rebuilding their basic beliefs about the relative benevolence of the world.     

Structure and mucoadhesion of mussel glue protein in dilute solution

Purified mussel adhesive protein mefp-1 (Mytilus edulis foot protein 1) has been studied regarding its state of oligomerization and gross conformation in dilute solution. Sedimentation equilibrium in the analytical ultracentrifuge of a dilute solution of protein (0.4 mg/mL) in acetate buffer at pH 4.5 and I = 0.10 M yielded an apparent molecular weight (whole distribution weight average, Mw, app) of 114 000 +/- 5000 via the "M" procedure, a value in almost exact agreement with the monomeric molecular weight obtained by MALDI mass spectrometry. At this low concentration, it is reasonable to assume thermodynamic ideality, i.e., Mw,app approximately Mw. This result, together with plots of point weight average apparent molecular weight versus concentration for three different loading concentrations (0.4, 0.8, 1.0 mg/mL), clearly demonstrates that this protein is essentially monomeric in dilute solution. Sedimentation velocity experiments yielded an estimate of the sedimentation coefficient s020,w = 2.34 +/- 0.17 S, which for M = 110 000 gives a frictional ratio f/f0 = 3.2 +/- 0.3. The interpretation of this, in terms of an extended rather than globular conformation for the structure of mefp-1 in dilute solution, is considered, within plausible limits of molecular hydration, and models for the structure in solution are considered, in light of the thermodynamic nonideality behavior of these molecules and previously published circular dichroism data. The significance of these observations in terms of the bioadhesive properties of mefp-1 is described, and the very strong interaction in dilute solution with a mucin glycoprotein is demonstrated.