Characterization and Performance Enhancement of Cement-Based Thermoelectric Materials.

Thermoelectric materials enable the direct conversion of thermal to electrical energy. One application of this is ambient heat energy harvesting where relatively stable temperature gradients existing between the inside and outside of a building could be utilized to produce electricity. Buildings can thus change from energy consumers to energy generators. This could ultimately help reduce the surface temperatures and energy consumption of buildings, especially in urban areas. In this paper, research work carried out on developing and characterizing a cement-based thermoelectric material is presented. Cement-based samples are doped with different metal oxides (Bi2O3 and Fe2O3) to enhance their thermoelectric properties, which are defined through their Seebeck coefficient, electrical conductivity and thermal conductivity. The study also discusses the positive impact of moisture content on the electrical conductivity.

Performance of Passive Samplers Analyzed by Computer-Controlled Scanning Electron Microscopy to Measure PM10-2.5.

We report on the precision and accuracy of measuring PM10-2.5 and its components with particles collected by passive aerosol samplers and analyzed by computer-controlled scanning electron microscopy with energy dispersive X-ray spectroscopy. Passive samplers were deployed for week-long intervals in triplicate and colocated with a federal reference method sampler at three sites and for 5 weeks in summer 2009 and 5 weeks in winter 2010 in Cleveland, OH. The limit of detection of the passive method for PM10-2.5 determined from blank analysis was 2.8 µg m(-3). Overall precision expressed as root-mean-square coefficient of variation (CVRMS) improved with increasing concentrations (37% for all samples, n = 30; 19% for PM10-2.5 > 10 µg m(-3), n = 9; and 10% for PM10-2.5 > 15 µg m(-3), n = 4). The linear regression of PM10-2.5 measured passively on that measured with the reference sampler exhibited an intercept not statistically different than zero (p = 0.46) and a slope not statistically different from unity (p = 0.92). Triplicates with high CVs (CV > 40%, n = 5) were attributed to low particle counts (and mass concentrations), spurious counts attributed to salt particles, and Al-rich particles. This work provides important quantitative observations that can help guide future development and use of passive samplers for measuring atmospheric particulate matter.

Elevated Concentrations of Lead in Particulate Matter on the Neighborhood-Scale in Delhi, India As Determined by Single Particle Analysis.

High mass concentrations of atmospheric lead particles are frequently observed in the Delhi, India metropolitan area, although the sources of lead particles are poorly understood. In this study, particles sampled across Delhi (August - December 2008) were analyzed by computer-controlled scanning electron microscopy with energy dispersive X-ray spectroscopy (CCSEM-EDX) to improve our understanding of the spatial and physicochemical variability of lead-rich particles (>90% lead). The mean mass concentration of lead-rich particles smaller than 10 µm (PM10) was 0.7 µg/m(3) (1.5 µg/m(3) std. dev.) with high variability (range: 0-6.2 µg/m(3)). Four samples (16% of 25 samples) with PM10 lead-rich particle concentrations >1.4 µg/m(3) were defined as lead events and studied further. The temporal characteristics, heterogeneous spatial distribution, and wind patterns of events, excluded regional monsoon conditions or common anthropogenic sources from being the major causes of the lead events. Individual particle composition, size, and morphology analysis indicate informal recycling operations of used lead-acid batteries as the likely source of the lead events. This source is not typically included in emission inventories, and the observed isolated hotspots with high lead concentrations could represent an elevated exposure risk in certain neighborhoods of Delhi.

Differences in the Judged Direction of Gaze From Heads Imaged in 3-D versus 2-D.

Observers viewed a model imaged on an LCD monitor in 3-D or 2-D as she gazed at points along a horizontally oriented meter stick from a distance of 80 cm. Her head was either straight or turned 20 degrees to the side, and for each head orientation, her gaze was straight, 10 degrees, or 20 degrees to the side, with her eyes individually open, both open, or both closed. For images in which both eyes were closed, the observers pointed along the same meter stick to where they judged her head to be pointed. When one or both eyes were open they judged where she appeared to be gazing. Gaze from the 2-D images agreed with previous studies. A comparison of the results from the 2-D versus 3-D images showed that the judgments were virtually identical for gaze from the straight versus turned head in all combinations of straight versus averted gaze, eyes individually open versus both open. The judgments were also virtually identical for head point. This suggests that 2-D studies that have used procedures similar to those described in this study may be applied to real world 3-D gaze perception.

The effect of head turn and illumination on the perceived direction of gaze.

Thirty observers judged the direction of monocular and binocular gaze from a model's LCD-imaged head when the head, gaze, and illumination were either straight or turned 20.6 degrees to the side. The judged direction of binocular eye contact from a turned head was judged to go past the direction of the observer, while judged monocular gaze from the eye toward the observer followed that for binocular gaze. Although judged monocular gaze from the eye away from the observer also passed the observer, it did so by a smaller amount. The judged direction of binocular gaze in the same direction as the head turn was judged to pass the direction of the head turn. The judged direction of monocular gaze from the eye away from the observer was nearly true, but the judged direction of monocular gaze from the eye toward the observer was judged as closer to the observer than true. Illumination of the model's head from the side made the direction of both head turn and gaze appear to move away from the direction of the light source. These results are discussed in connection with angle k and the perceived direction of head turn.

Was Rembrandt strabismic?

PURPOSE: We studied a set of Rembrandt's self-portraits to reassess a previous claim, based on measurements of the centration of his painted irises, that Rembrandt had a large exotropia. METHODS: Of the 24 self-portraits that Rembrandt painted, with significant ocular detail to give an impression of the direction of his gaze, we scanned 10; the five with the largest difference in centration between the irises and the five with the smallest difference. The right and left eyes in each image were then occluded using Photoshop to produce two additional images that gave monocular gaze. Thirty observers then judged where the portraits appeared to be gazing within the plane of their face. RESULTS: Although our observers did judge a significant outward deviation for gaze between the two eyes, part of this was caused by an outward deviation from central by the presumably nonstrabismic eye. Any greater amount of outward deviation from the "strabismic" than the nonstrabismic eye can then be explained by a gaze overshoot induced by head turn, painting with a mirror, and angle kappas. In addition, Rembrandt's apparent strabismus is seen only in those portraits painted during a few years early in his career, and portraits that Rembrandt and his students produced of other presumably nonstrabismic individuals often give a similar impression of strabismus. CONCLUSIONS: There are several factors that can explain why some of Rembrandt's self-portraits make him look strabismic without concluding that he actually was. Rembrandt and his students may also have painted this appearance as an artistic style.

Heterogeneity of coarse particles in an urban area.

The variation in composition and concentration of coarse particles in Rochester, a medium-sized city in western New York, was studied using UNC passive samplers and computer-controlled scanning electron microscopy (CCSEM). The samplers were deployed in a 5 × 5 grid (2 km × 2 km per grid cell) for 2-3 week periods in two seasons (September 2008 and May 2009) at 25 different sites across Rochester. CCSEM analysis yielded size and elemental composition for individual particles and analyzed more than 800 coarse particles per sample. Based on the composition as reflected in the fluoresced X-ray spectrum, the particles were grouped into classes with similar chemical compositions using an adaptive resonance theory (ART) network. The mass fractions of particles in the identified classes were then used to assess the homogeneity of composition and concentration across the measurement domain. These results illustrate how particle sampling using the UNC passive sampler coupled with CCSEM/ART can be used to determine the concentration and source of the coarse particulate matter at multiple sites. The particle compositions were dominated by elements suggesting that the major particle sources are road dust and biological particles. Considerable heterogeneity in both composition and concentration were observed between adjacent sites as indicated by cofficient of divergence analyses.

Influence of the direction of eye turn on the appearance of strabismus.

PURPOSE: The purpose of this study was to determine whether an equal amount of exotropia (XT) or esotropia (ET) produces a more noticeable eye turn, which gives the better impression of eye contact, and how a positive angle kappa (K) affects this judgment. METHODS: Images from a white male model were manipulated to simulate 0, 5, 10, and 15° of ET and XT for both 0 and +5° K. A series of image pairs was then created that juxtaposed XT and ET of equal angles for both 0 and +5° K. Forty-five optometry students then judged which image in each pair appeared to have the greater tropia and which gave the greater impression of eye contact. RESULTS: When angle kappa was 0, there was no significant difference in whether XT or ET appeared to be more noticeable. However, when angle kappa was +5°, an XT of 5° or greater became more apparent than an equal ET (p < 0.001). However, when the criterion was eye contact, ET gave the greater impression that eye contact was being made when the deviation was 10° or more, and this was true for both 0 and +5° K (p < 0.001). CONCLUSIONS: When a strabismus is to be evaluated or corrected purely for cosmetic reasons, the results may differ depending on the value of angle kappa and whether the criterion for good cosmesis is ocular deviation or eye contact.

Perceived direction of gaze from eyes with dark vs. light irises.

PURPOSE: Much of the previous research on the perceived direction of gaze has not specified eye color or pupil visibility. This study tests whether the lightness or darkness of a gazer's irises (typically brown vs. blue) affects their perceived direction of gaze. METHODS: Twenty-five observers judged the direction of horizontal gaze from a model whose LCD-imaged head gazed toward points on the plane of the observer's face. The model's head was displayed with its natural brown irises and also with its irises digitally altered to look blue without pupils, blue with centered pupils, and blue with nasally decentered pupils. True gaze location was compared with the judged gaze location for each type of iris. RESULTS: For all iris types, observers judged that monocular gaze was biased outward from its true direction for all gaze locations, including central, whereas binocular gaze was close to centered and had a greater slope. Blue eyes with no pupil and blue eyes with a centered pupil exaggerated this perceived outward deviation for monocular gaze but binocular gaze remained the same. When the pupils were nasally decentered by a typical amount, straight monocular as well as binocular gaze appeared to be centered. CONCLUSIONS: The direction of monocular gaze from eyes that differ in the darkness of their irises is perceived differently, and, within the blue irises, small differences in pupil centration made surprisingly large differences in the perceived directions of gaze.

Differences in the perception of monocular and binocular gaze.

PURPOSE: The judged direction of side gaze from a straight head is known to be biased from its true direction. This study reports the specific biases in the perceived direction of gaze from right, left, or both eyes when targets are in the plane of the observer or in a plane in front of the observer. Theories are discussed about the ocular cues that are used to determine the perceived direction of gaze. METHODS: Two sets of 16 observers judged the direction of gaze from each of two models whose LCD-imaged heads gazed toward points that were either on the plane of the observers' faces or on a plane that was midway between the models and observers. RESULTS: For both distant and near targets, straight monocular gaze from the right and left eyes appeared to be mildly exotropic, as expected from the positive angle kappa of the models, but straight binocular gaze appeared orthotropic. However, when binocular gaze was toward the side, the perceived direction of gaze differed significantly between the two eyes, and for this condition, the perception of binocular gaze followed that of the abducting eye. CONCLUSION: When the perceived directions of monocular gaze from the two eyes do not agree, the perceived direction of binocular gaze resolves this conflict by matching that of the abducting eye.

The effect of head turn on the perception of gaze.

When subjects viewed straight and turned eyes that were isolated singly or in pairs from a head that was straight or turned, they underestimated their true direction of gaze. They also underestimated the direction of head turn when both eyes were closed. However, the judged direction of gaze was improved when the eyes were layered against the heads. Judged direction of averted gaze was primarily based on the abducting eye. The effect that the deviation between an eye's optical axis and its true direction of gaze (angle kappa) has on its judged direction of gaze is discussed.

Influence of the epicanthal fold on the perceived direction of gaze.

PURPOSE: Judged direction of gaze from straight and turned heads is known to be biased from its true direction. We have tested the additional influence of epicanthal folds on the perceived direction of gaze. METHODS: Western observers (U.S. residents of Western appearance) and Eastern observers (native Japanese) judged the direction of gaze from cathode ray tube-imaged heads with and without epicanthal folds (Japanese vs. Western models) when the heads, both straight and turned, gazed in different lateral directions. RESULTS: When the gazers' heads were straight and gave eye contact, both Western and Eastern observers judged the gaze to be giving eye contact. However, with straight heads and gaze to the side, epicanthal folds produced significant differences in the judged direction of gaze. Observers judged the right and left eyes to be gazing in nearly the same direction when the gazer had the eye appearance that the observers were used to viewing within their own country, but in very different directions when the gazer had eyes typical of the other country. When the gazers' heads were turned, the Western and Eastern observers judged the direction of gaze of the Western gazer's right and left eyes similarly, but both judged large differences in direction of gaze between right and left eyes for the Eastern gazer. CONCLUSION: Direction of gaze from eyes that have epicanthal folds is judged very differently than gaze from eyes that do not have epicanthal folds. This difference is sensitive to the cultural experience of the observers.

Redirecting gaze to improve the cosmetic appearance of strabismus.

PURPOSE: We studied a behavioral technique in which strabismics can reduce the detectability of their eye turn by appropriately redirecting their gaze. We tested the efficacy of this technique for various amounts of strabismus and different positions of gaze. METHODS: We took digital images of a model gazing in different lateral directions and digitally edited them to simulate fixation with one eye on different lateral locations whereas the other eye was misaligned from the first by +/-0, 6, 12, 18, 24, and 30 Delta. Then we asked 22 lay observers to examine each of the images and to report whether or not they perceived eye contact and normal gaze. RESULTS: The observers reported that our model appeared to look normal and gave them eye contact two-thirds of the time for up to 18 Delta of exotropia and 12 of esotropia when she looked half her prismatic deviation to the side opposite her eye turn. CONCLUSION: By appropriately directing their gaze, both exotropes and esotropes can improve the cosmetic appearance of their strabismus and increase the perception that they are looking at the observer. This may be useful during job interviews and other social encounters where eye contact and a good impression are critical. A drawback is that large amounts of strabismus may require the gazer to look far to the side of the observer's head where it may be difficult to maintain gaze and the observer's facial expression may be hard to read. However, all patients may be counseled on which eye to look at when engaging in conversation, as looking at the appropriate rather than the inappropriate eye can reduce the perceived amount of their strabismus. Also, when their portrait is being taken, the full amount of eccentric gaze could easily be used.

Gaze as depicted in Vermeer's Girl with a Pearl Earring.

Ten observers viewed Vermeer's painting Girl With a Pearl Earring and estimated her direction of gaze when her eyes were exposed together and separately. The observers also viewed the painting when her eyes were digitally replaced by those of a real person. The authors found that Vermeer painted the girl's eyes with a precision that was near the limits of visual acuity. Also, Vermeer included 3 gaze illusions, none of which researchers have documented as known in Vermeer's time: (a) when a model whose head is turned to one side gazes at an observer, there is an illusion that she is looking to the side of the observer away from the direction of her head turn; (b) when a model's eyes are viewed separately, they appear to gaze outward relative to each other; and (c) when both of a model's eyes are viewed, the perceived direction of gaze follows that of the nearer eye.

Comparisons of dynamic retinoscopy measurements with a print card, a video display terminal, and a PRIO System Tester as test targets.

BACKGROUND: Dynamic retinoscopy is a common clinical test for assessment of visual function in patients with symptoms related to computer use. It has been suggested that performing dynamic retinoscopy with a fixation target resembling a computer screen may be valuable in the examination of computer users. However, such targets differ in luminance and other characteristics from the printed paper test cards typically used for dynamic retinoscopy. METHOD: To address the effect of varying test targets on dynamic retinoscopy results, this study compared lag of accommodation results from dynamic retinoscopy with three different fixation targets: (a) a printed paper target, (b) a video display terminal, and (c) the PRIO vision testing device, which is designed to simulate a computer screen. MEM (monocular estimate method) dynamic retinoscopy was performed with the print target and with the PRIO device. RESULTS: The difference between results with the different test conditions were generally small, with a statistically significant 0.32 D lower lag found on MEM retinoscopy with the PRIO target IMEM-PRIO) than on MEM retinoscopy with a print target (MEM-PRINT). Mean lag measurements on MEM with a print target and on Nott retinoscopy with the video display terminal (NOTT-VDT) were only 0.04 D different. The 95% limits of agreement for the difference between MEM-PRINT and MEM-PRIO (+/- 0.6 D) was similar to the 95% limits of agreement for the interexaminer reliability of the two procedures (+/- 0.6 D for MEM-PRINT and +/- 0.7 D for MEM-PRIO). CONCLUSION: There was a small but statistically significant difference in lag of accommodation measured with MEM dynamic retinoscopy on the PRIO testing device when compared to a print card.

Measurement of refractive errors in young myopes using the COAS Shack-Hartmann aberrometer.

PURPOSE: To evaluate the Complete Ophthalmic Analysis System (COAS; WaveFront Science) for accuracy, repeatability, and instrument myopia when measuring myopic refractive errors. METHODS: We measured the refractive errors of 20 myopic subjects (+0.25 to -10 D sphere; 0 to -1.75 D cylinder) with a COAS, a phoropter, and a Nidek ARK-2000 autorefractor. Measurements were made for right and left eyes, with and without cycloplegia, and data were analyzed for large and small pupils. We used the phoropter refraction as our estimate of the true refractive error, so accuracy was defined as the difference between phoropter refraction and that of the COAS and autorefractor. Differences and means were computed using power vectors, and accuracy was summarized in terms of mean vector and mean spherocylindrical power errors. To assess repeatability, we computed the mean vector deviation for each of five measurements from the mean power vector and computed a coefficient of repeatability. Instrument myopia was defined as the difference between cycloplegic and noncycloplegic refractions for the same eyes. RESULTS: Without cycloplegia, both the COAS and autorefractor had mean power vector errors of 0.3 to 0.4 D. Cycloplegia improved autorefractor accuracy by 0.1 D, but COAS accuracy remained the same. For large pupils, COAS accuracy was best when Zernike mode Z4(0) (primary spherical aberration) was included in the computation of sphere power. COAS repeatability was slightly better than autorefraction repeatability. Mean instrument myopia for the COAS was not significantly different from zero. CONCLUSIONS: When measuring myopes, COAS accuracy, repeatability, and instrument myopia were similar to those of the autorefractor. Error margins for both were better than the accuracy of subjective refraction. We conclude that in addition to its capability to measure higher-order aberrations, the COAS can be used as a reliable, accurate autorefractor.

The effect of changing from glasses to soft contact lenses on myopia progression in adolescents.

At the end of a clinical trial of bifocals as myopia treatment, subjects were allowed to select any type of optical correction they wished and were asked to return in 1 year. This report gives results of that last examination with emphasis on how progression rates differed between those remaining in their original type of glasses compared with those who switched to soft contact lenses. We found that myopia progressed at an age-adjusted average rate of 0.74 D in 19 children who switched to soft contact lens wear compared with 0.25 D for 24 children remaining in glasses (p < 0.0001). Increased growth of the vitreous chamber appeared to account for much of this excess myopia progression, although the difference in that variable did not reach statistical significance (p = 0.101). We also noted a 0.203 D steepening in the corneal curvature in contact lens wearers compared with spectacle wearers whose corneas steepened very little (0.014 D, p = 0.007). Soft contact lens wear was also accompanied by a greater change in the near-point phoria which moved 4.5 prism dioptres in the exo direction compared with spectacle wearers who experienced only a 1.4 prism dioptre divergent shift (p = 0.048).

Prohibitins and Ras2 protein cooperate in the maintenance of mitochondrial function during yeast aging.

The yeast Saccharomyces cerevisiae has a finite replicative life span. Yeasts possess two prohibitins, Phb1p and Phb2p, in similarity to mammalian cells. These proteins are located in the inner mitochondrial membrane, where they are involved in the processing of newly-synthesized membrane proteins. We demonstrate that the elimination of one or both of the prohibitin genes in yeast markedly diminished the replicative life span of cells that lack fully-functional mitochondria, while having no effect on cells with functioning mitochondria. This deleterious effect was suppressed by the deletion of the RAS2 gene. The expression of PHB1 and PHB2 declined gradually up to 5-fold during the life span. Cells in which PHB1 was deleted in conjunction with the absence of a mitochondrial genome displayed remarkable changes in mitochondrial morphology, distribution, and inheritance. This loss of mitochondrial integrity was not seen in cells devoid of PHB1 but possessing an intact mitochondrial genome. In a subset of the cells, the changes in mitochondrial integrity were associated with increased production of reactive oxygen species, which co-localized with the altered mitochondria. The mitochondrial deficits described above were all suppressed by deletion of RAS2. Our data, together with published information, are interpreted to provide a unified view of the role of the prohibitins in yeast aging. This model posits that the key initiating event is a decline in mitochondrial function, which leads to progressive oxidative damage that is exacerbated in the absence of the prohibitins. This aggravation of the initial damage is ameliorated by the suppression of the production of mitochondrial proteins in the absence of Ras2p signaling of mitochondrial biogenesis.