Modelling Drainage Performance in an Indian Catchment

Surface-water flooding occurs frequently in low-income urban settlements of developing countries, with impacts on public health and the local economy. In many locations, drainage systems are neither appropriate nor sustainable. A computer model of a small surface-water drainage catchment has been developed within a slum improvement programme in Indore, India. The model was calibrated and verified against flow-survey data, and was used to study the effects on performance of maintenance (as reflected in solids build-up in pipes) and site grading. The results confirm the critical importance of maintenance in drainage performance and the need for construction engineers to consider drainage carefully before changing site-grading plans. The results also suggest some general trends in drainage performance during floods.     

Determinants of help seeking: Relations between perceived reasons for classroom help-avoidance and help-seeking behaviors in an experimental context.

It was predicted that orientations to help-avoidance (HA) would predict styles of help seeking (HS). In Study 1, a total of 1,029 pupils aged 10–12 years rated reasons for HA in math class. Ratings formed 3 factors reflecting autonomous strivings for independent mastery, ability-focused concerns to mask poor ability, and expedient perceptions that help would not expedite task completion. In Study 2, a total of 272 pupils who had endorsed one or another HA orientation could request help for math problems. An autonomous orientation was associated with autonomous HS, which promoted independent mastery, and an expedient orientation with executive HS, which expedited task completion. Pupils, especially boys, with an ability-focused orientation exhibited avoidant-covert HS: they requested least help and were most likely to cheat. HS was moderated by perceived threat to competence (ability-focused orientation) but not by perceived competence. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Isolators, polarizers, and other optical waveguide devices using a resonant-layer effect

This paper investigates the effect of a high-refractive-index layer added onto the clad layer of an optical waveguide. With proper design, the value of the fundamental mode's confinement factor in the added layer can exhibit a resonance. This resonance depends on the added layer's location, thickness, complex index, and wavelength of operation. If loss is incorporated into this added layer, relatively small changes in waveguide properties can result in large changes in loss. This phenomenon is referred to in this paper as the resonant-layer effect (RLE). A number of devices, including isolators, polarizers, and modulators, can be made and/or improved by using the RLE. As examples, this paper describes an integratable isolator giving 240-dB/cm isolation and 13-dB/cm insertion loss, an integratable polarizer with 90-dB/cm rejection and about 0.8-dB/cm insertion loss, and a 300-/spl mu/m-long modulator requiring electric fields of /spl plusmn/5 V//spl mu/m for /spl sim/45% intensity modulation. In general, the resonant layer need not be epitaxial with the waveguide, allowing for integration with a variety of material systems.     

Human respiratory muscles: sensations, reflexes and fatiguability

1. Given the importance of the ventilatory 'pump' muscles, it would not be surprising if they were endowed with both sensory and motor specializations. The present review focuses on some unexpected properties of the respiratory muscle system in human subjects. 2. Although changes in blood gas tension were long held not to influence sensation directly, studies in subjects who are completely paralysed show that increases in arterial CO2 levels elicit strong sensations of respiratory discomfort. 3. Stretch reflexes in human limb muscles contain a monosynaptic spinal excitation and a long-latency excitation. However, inspiratory muscles show an initial inhibition when tested with brief airway occlusions during inspiration. This inhibition does not depend critically on input from pulmonary or upper airway receptors. 4. Human inspiratory muscles (including the diaphragm) have been considered to fatigue during inspiratory resistive loading. However, recent studies using phrenic nerve stimulation to test the force produced by the diaphragm show that carbon dioxide retention (hypoventilation) and voluntary cessation of loading occur before the muscles become overtly fatigued.     

A biocultural perspective on Marianas prehistory: recent trends in bioarchaeological research

Fifteen years ago, the biohistory of Micronesia was still a blank slate relative to other regions of the Pacific. Since 1980, however, the Mariana Islands, one of the largest island chains in Micronesia, have been the focus of intensive archaeological investigation and human remains have been ubiquitous components of the archaeological assemblages recovered from the islands of Guam, Rota, Tinian, and Saipan. These investigations have provided us with a wealth of new data that will contribute substantially to our understanding of population adaptation to island ecosystems in this part of the Pacific. Much of the recent bioarchaeological research in the Marianas is the product of archaeological mitigation rather than directed research. Consequently, many of our research efforts have been articulated with the needs of cultural resource management (CRM) where research designs focus on several general problem areas: 1) subsistence adaptation with emphasis on the contribution of marine vs. terrestrial resources and the role of pelagic, or deep-ocean resources in the marine component of the diet; 2) regional (upland vs. coastal; interisland) and temporal variation in subsistence/settlement; and 3) geomorphologic variation in coastal sediments, particularly as influenced by storm events.     

Wavelength tuning of fiber Bragg gratings over 90 nm using a simple tuning package

We demonstrate a silica-based tunable fiber Bragg grating filter with a wavelength tuning range over 90 nm. A bend-tuning technique in a simple tuning package is employed to obtain a wide wavelength tuning range from 1634 to 1544 nm, covering the entire L-band and a half of the C-band. The polarization-mode dispersion and polarization-dependent loss of the device show little variations over the whole operating region.     

Characterization of immiscibly blended polyurethane coatings part 1: selective staining for enhanced micro-Raman spectroscopy

Raman spectroscopy (RS) mapping of the selective infiltration of styrene monomer has been developed as a protocol for polymeric phase identification in resin-blended thermoset powder coatings. Blends of incompatible acrylic polyols, with low and high hydroxyl contents, combined with matting agents and pigments, were crosslinked to produce unique low gloss thermosets. The low reflectance originated from a synergistic effect between the polymeric phase separation and the incorporation of the matting agents and pigments. RS conclusively identified the phases within the blended film using polyester-embedded cross-section samples. Further analysis has revealed that monomeric styrene from the polyester-embedding resin produced the spectroscopic handle necessary for domain identification. Preferential infiltration of styrene was therefore investigated through dip and vapor staining of the blended and individual resin films. The spectroscopic handle had manifested through the consistent infiltration of styrene within the low hydroxyl film. The contamination in the cross-sections was eliminated when an epoxy-embedding resin was utilized, which produced no such marker peak in the ensuing spectra. These observations led to the development of the described selective staining protocol for micro-Raman analysis, which enabled very reproducible results for enhanced chemical mapping of phase-separated coatings.     

Weakly Coupled Relaxor Behavior of BaTiO3–BiScO3 Ceramics

The structural and dielectric properties of (1− x )BaTiO₃– x BiScO₃ ( x =0–0.5) ceramics were investigated to acquire a better understanding of the binary system, including determination of the symmetry of the phases, the associated dielectric properties, and the differences in the roles of Bi₂O₃ and BiScO₃ substitutions in a BaTiO₃ solid solution. The solubility limit for BiScO₃ into the BaTiO₃ perovskite structure was determined to be about x =0.4. A systematic structural change from the ferroelectric tetragonal phase to a pseudo-cubic one was observed at about x =0.05–0.075 at room temperature. Dielectric measurements revealed a gradual change from proper ferroelectric behavior in pure BaTiO₃ to highly diffusive and dispersive relaxor-like characteristics from 10 to 40 mol% BiScO₃. Several of the compositions showed high relative permittivities with low-temperature coefficients of capacitance over a wide range of temperature. Quantification of the relaxation behavior was obtained through the Vogel–Fulcher model, which yielded an activation energy of 0.2–0.3 eV. The attempt characteristic frequency was 10¹³ Hz and the freezing temperature, T _f, ranged from −177° to −93°C as a function of composition. The high coercive fields, low remanent polarization, and high activation energies suggest that in the BiScO₃–BaTiO₃ solid solutions, the polarization in nanopolar regions is weakly coupled from region to region, limiting the ability to obtain long-range dipole ordering in these relaxors under field-cooled conditions.