Glasses Tech - Prescription Glasses, Prescription Eyeglasses » Glasses 2002

Looking Through the Glasses: J. D. Salinger’s Wise Children and Gifted Education

admin — Mon, 08 Mar 2010 05:18:41 +0000

Gifted children are often Big Picture thinkers (Schultz & Delisle, 1997). Even as young children, they may ask profound questions and view life from the perspective of The Most Important Things: meaning, goodness, truth, spirituality, death, and the like. J. D. Salinger’s stories about the gifted and precocious Glass children offer a vivid, provocative, and very useful description of a spiritual Big Picture perspective on life. This essay describes the Glasses’ spiritual development and draws out implications of their thinking and dilemmas for a critique of gifted education. It suggests that gifted education can adequately address the spiritual life of gifted students and other “Big Picture” perspectives only by becoming concerned with educating gifted children for life.

Barry Grant
University of Maryland/University College, Schwdbisch Gmund, Germany

Gifted Child Quarterly, Vol. 46, No. 1, 6-14 (2002)
DOI: 10.1177/001698620204600102

Development of a Novel Composite Based on Thermoplastic Polymers and Low Melting Point Thermoplastic Chalcogenide Glasses

admin — Mon, 08 Mar 2010 05:09:43 +0000

A novel composite material has been developed based on thermoplastic polymers on one hand and thermoplastic chalcogenide glass on the other hand. Extrusion technique and pressing allowed the production of very different structures of the composite, ranging from fibrous to “sandwich” structures. Also obtained were highly homogenous compositions that contain perfectly spherical glass particles of 1-6 mm in diameter dispersed into a polymer matrix.

Optical properties of the composite have been studied thoroughly. It was established that extrusion allows the obtaining of composites, which are highly transparent in the 2-25 mm wavelength band when the concentration of the chalcogenide glass does not exceed 33%. When the concentration of chalcogenide glass was as great as 40%, dramatic changes in the transmission spectrum were observed. The extruded films are opaque not only in the visible band but in the near and middle IR as well, while being transparent in the far IR band. Such composite films are suitable as far IR filters.

Pressing permits the production of “sandwiches” which are opaque in visible light and highly transparent in the near and middle IR. “Sandwich” composites could be used as effective flexible near-IR filters. Oriented composites can be applied as IR waveguides.

Key Words: composite • polymer • thermoplastic • chalcogenide • IR • spectrum • oriented • “sandwich” • filter

Journal of Thermoplastic Composite Materials, Vol. 15, No. 6, 511-523 (2002)
DOI: 10.1177/0892705702015006212
Edward Bormashenko
The College of Judea and Samaria, The Research Institute, 44837, Ariel, Israel, polytris@netvision.net.il

Roman Pogreb

The College of Judea and Samaria, The Research Institute, 44837, Ariel, Israel

Semion Sutovsky

Polytris LTD, Israel, P.O.B. 3, 44837, Ariel, Israel, Polytris

Progression of Childhood Myopia in Soft Contact Lenses and Glasses

admin — Mon, 08 Mar 2010 05:08:49 +0000

Purpose: to examine the effect of correction type on myopia progression in subjects who completed a randomized clinical trial of bifocal glasses.
Methods: Forty nine of 55 subjects, who completed a 42-month clinical trial, returned for a 1-yr post-treatment visit (54 months of follow-up). Original treatment assignments were single-vision glasses (SV) or bifocal glasses (BF) with a +1.50 D add. Once released from treatment, children chose either to wear soft contact lenses (CL), to continue in their assigned glasses, or to switch to the other type of glasses. Progression during that year, i.e. from 42 to 54 mos., was used to estimate the effect of switching correction type. Myopia was measured with automated refraction 30 min after instilling two drops of 1% tropicamide. We used ANOVA with age as co-variate and averaged myopia over both eyes. Means presented here are age-adjusted.
Results: In the SV group, seven children who switched to CL progressed 1.8 x faster than the twelve children who remained in BF (p=0.005), those remaining in SV progressing an average of 0.27 D compared to 0.75 D for those switching to CL. In the BF group, twelve children who switched to CL progressed 1.9 x faster than the twelve who remained in SV (p=0.001), those remaining in BF progressing an average of 0.26 D compared to 0.75 D for those switching to CL. Three children from the original SV group who switched to BF on average decreased in myopia by 0.08 D compared to an increase of 0.27 D for the twelve remaining in SV (p=0.02).
Conclusion: In the children we studied, wearing soft-contact lenses seemed to increase myopia progression compared to wearing either single-vision or bifocal glasses.

Keywords: 357 clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials • 481 myopia • 367 contact lens
GW Fulk1, LA Cyert2 and DE Parker3
1 College of Optometry Northeastern State University Tahlequah OK
2 Tahlequah OK
3 Biostatistics and Epidemiology Univ of Oklahoma Health Science Center Oklahoma City OK

Commercial Relationships: G.W. Fulk, None; L.A. Cyert, None; D.E. Parker, None.
Grant Identification: NIH EY10613

Mantle-melt Evolution (Dynamic Source) in the Origin of a Single MORB Suite: a Perspective from Magnesian Glasses of Macquarie Island

admin — Mon, 08 Mar 2010 04:41:17 +0000

The effects of source composition and source evolution during progressive partial melting on the chemistry of mantle-derived mid-ocean ridge basalt (MORB) melts were tested using a comprehensive geochemical and Sr–Nd–Pb isotopic dataset for fresh, magnesian basaltic glasses from the Miocene Macquarie Island ophiolite, SW Pacific. These glasses: (1) exhibit clear parent–daughter relationships; (2) allow simple reconstruction of primary melt compositions; (3) show exceptional compositional diversity (e.g. K2O/TiO2 0·09–0·9; La/Yb 1·5–22; 206Pb/204Pb 18·70–19·52); (4) preserve changes in major element and isotope compositions, which are correlated with the degree of trace element enrichment (e.g. La/Sm). Conventional models for MORB genesis invoke melting of mantle that is heterogeneous on a small scale, followed by binary mixing of variably lithophile element-enriched melt batches. This type of model fails to explain the compositions of the Macquarie Island glasses, principally because incompatible element ratios (e.g. Nb/U, Sr/Nd) and Pb isotope ratios vary non-systematically with the degree of enrichment. We propose that individual melt batches are produced from instantaneous ‘parental’ mantle parageneses, which change continuously as melting and melt extraction proceeds. This concept of a ‘dynamic source’ combines the models of small-scale mantle heterogeneities and fractional melting. A dynamic source is an assemblage of locally equilibrated mantle solids and a related melt fraction. Common MORB magmas that integrate the characteristics of numerous melt batches therefore tend to conceal the chemical and isotopic identity of a dynamic source. This study shows that isotope ratios of poorly mixed MORB melts are a complex function of the dynamic source evolution, and that the range in isotope ratios within a single MORB suite does not necessarily require mixing of diverse components.

KEY WORDS: mid-ocean ridge basalt; Macquarie Island; radiogenic isotopes; mantle; geochemistry

VADIM S. KAMENETSKY1,* and ROLAND MAAS2,
1SCHOOL OF EARTH SCIENCES AND CENTRE FOR ORE DEPOSIT RESEARCH, UNIVERSITY OF TASMANIA, GPO BOX 252-79, HOBART, TASMANIA, 7001, AUSTRALIA
2DEPARTMENT OF EARTH SCIENCES, LA TROBE UNIVERSITY, BUNDOORA, VICTORIA 3083, AUSTRALIA

“Drink at least eight glasses of water a day.” Really? Is there scientific evidence for “8 × 8″?

admin — Mon, 08 Mar 2010 04:39:49 +0000

Despite the seemingly ubiquitous admonition to “drink at least eight 8-oz glasses of water a day” (with an accompanying reminder that beverages containing caffeine and alcohol do not count), rigorous proof for this counsel appears to be lacking. This review sought to find the origin of this advice (called “8 × 8″ for short) and to examine the scientific evidence, if any, that might support it. The search included not only electronic modes but also a cursory examination of the older literature that is not covered in electronic databases and, most importantly and fruitfully, extensive consultation with several nutritionists who specialize in the field of thirst and drinking fluids. No scientific studies were found in support of 8 × 8. Rather, surveys of food and fluid intake on thousands of adults of both genders, analyses of which have been published in peer-reviewed journals, strongly suggest that such large amounts are not needed because the surveyed persons were presumably healthy and certainly not overtly ill. This conclusion is supported by published studies showing that caffeinated drinks (and, to a lesser extent, mild alcoholic beverages like beer in moderation) may indeed be counted toward the daily total, as well as by the large body of published experiments that attest to the precision and effectiveness of the osmoregulatory system for maintaining water balance. It is to be emphasized that the conclusion is limited to healthy adults in a temperate climate leading a largely sedentary existence, precisely the population and conditions that the “at least” in 8 × 8 refers to. Equally to be emphasized, lest the message of this review be misconstrued, is the fact (based on published evidence) that large intakes of fluid, equal to and greater than 8 × 8, are advisable for the treatment or prevention of some diseases and certainly are called for under special circumstances, such as vigorous work and exercise, especially in hot climates. Since it is difficult or impossible to prove a negativein this instance, the absence of scientific literature supporting the 8 × 8 recommendationthe author invites communications from readers who are aware of pertinent publications.

fluid intake; optimal fluid intake; daily water intake; water balance
Heinz Valtin
(With the Technical Assistance of Sheila A. Gorman)
Department of Physiology, Dartmouth Medical School, Lebanon, New Hampshire 03756

Si-F bonding in aluminosilicate glasses: Inferences from ab initio NMR calculations

admin — Mon, 08 Mar 2010 04:37:04 +0000

Although it has been well accepted that F-Al linkages dominate in F-bearing alkali aluminosilicate glasses, the possibility of F-Si linkages remains unresolved. Recent 19F NMR results have been interpreted as indicative of not only the presence of the Al-F-Na(n) linkages but also of the presence of Si-F-Na(n) linkages. High level ab initio NMR calculations were performed to investigate the nature of possible species contributing to the 19F spectra.

The B3LYP/6-31G* level was used to optimize structures and a scaling technique applied to the calculation of NMR properties using both HF and B3LYP methods at the 6-311+G(2df,p) level. The applicability of this scaling method was checked by comparing calculated results against experimental data on several crystalline materials; the results are improved over HF or DFT methods alone. The calculation results show that none of the F-Al species investigated can produce the –147 ppm peak of Schaller et al. (1992). However, several species in which F is bonded to fourfold-, fivefold-, and sixfold-coordinated Si produce a 19F chemical shift of approximately –147 ppm. These results verify the assignments of this peak by Zeng and Stebbins (2000) to tetrahedral Si-F and NaSiF6-like species, and rule out many other possible species. Several additional species such as a fivefold coordinated Si-F species may further contribute to the –147 ppm 19F peak.
Yun Liu* and Hanna Nekvasil
Center for High Pressure Research and Department of Geosciences, State University of New York, Stony Brook, New York 11794-2100, U.S.A.

Correspondence: * E-mail: yunliu@ic.sunysb.edu

Molecular orbital calculations on aluminosilicate tricluster molecules: Implications for the structure of aluminosilicate glasses

admin — Mon, 08 Mar 2010 04:32:42 +0000

Ab initio, molecular orbital calculations were carried out to study the energetic stability and NMR characteristics of “triclusters” of composition [T(XO)(OH)2]O[Al(OH)3][T(OH)3] (X = no atom, H+, Li+, Na+, K+, Mg2+, or Ca2+; T = Si4+ or Al3+). These triclusters consist of a central oxygen atom in trigonal coordination (IIIO) surrounded by three tetrahedrally coordinated, network-forming cations (Al and Si). All tricluster configurations modeled are predicted to be dynamically stable except for one containing three Al3+ cations. Tricluster viability was further tested by computing energetic stabilities relative to Al(OH)3 and dimers with non-bridging oxygen atoms (NBO). With these species as reactants and T = Si4+, calculated reaction energies vary from –87 kJ/mol with X = H+, to –253 kJ/mol with X = Mg2+. For the case of X = Ca2+, where structures with 1 Si and 2 Al were also modeled, the reaction energy was found to be over 50 kJ/mol more negative in the latter case (–278 kJ/mol compared to –222 kJ/mol). However, when the energy of the triclusters [Si(Na+O)(OH)2]O [Al(OH)3][Si(OH)3] and [Al(Ca2+O)(OH)2]O[Al(OH)3][Si(OH)3] was calculated relative to isochemical chains of three tetrahedra without NBO or IIIO, the triclusters were predicted to be +124 and +142 kJ/mol less stable than the corresponding trimer chains. Although these latter computed energy changes do not preclude formation of triclusters, they imply that such species should occur only in minor concentrations.

To help identify IIIO within aluminosilicate glasses, predictions of 17O NMR chemical shifts (17O), quadrupolar coupling constants (QCCs), and asymmetry parameters () are also presented. When compared with predictions of 17O NMR parameters in a number of molecules representing Si and Al-bearing Q4 species, it is found that the calculated parameters for IIIO are generally within the range of normal bridging oxygen atoms (BO). Thus, if IIIO are a minor percentage of oxygen atoms within a glass, we conclude that their identification may be difficult using NMR spectroscopy.
J.D. Kubicki1,* and M.J. Toplis2
1 Department of Geosciences, The Pennsylvania State University, University Park, Pennsylvania 16802, U.S.A
2 CRPG-CNRS, BP 20, F-54501, Vandoeuvre-lès-Nancy, France

Correspondence: * E-mail: kubicki@geosc.psu.edu

Volatiles in basaltic glasses from a subglacial volcano in northern British Columbia (Canada): implications for ice sheet thickness and mantle volatiles

admin — Mon, 08 Mar 2010 04:31:27 +0000

Dissolved H2O, CO2, S and Cl concentrations were measured in glasses from Tanzilla Mountain, a 500 m-high, exposed subglacial volcano from the Tuya-Teslin region, north central British Columbia, Canada. The absence of a flat-topped subaerial lava cap and the dominance of pillows and pillow breccias imply that the Tanzilla Mountain volcanic edifice did not reach a subaerial eruptive phase. Lavas are dominantly tholeiitic basalt with minor amounts of alkalic basalt erupted at the summit and near the base. Tholeiites have roughly constant H2O (c.0.56 ± 0.07 wt%), CO2 (<30 ppm), S (980 ± 30 ppm) and Cl (200 ± 20 ppm) concentrations. Alkalic basalts have higher and more variable volatile concentrations that decrease with increasing elevation (0.62–0.92 wt% H2O, <30 ppm CO2, 870–1110 ppm S and 280–410 ppm Cl) consistent with eruptive degassing. Calculated vapour saturation pressures for the alkalic basalts are 36 to 81 bars corresponding to ice thicknesses of 400 to 900 m. Maximum calculated ice thickness (c. 1 km) is at the lower end of the range of predicted maximum Fraser glaciation (c. 1–2 km), and may indicate initiation of volcanism during the waning stages of glaciation. Temporal evolution from tholeiitic to alkalic compositions may reflect compositional gradients within a melting column, instead of convective processes within a stratified magma chamber. The mantle source region for the subglacial volcanoes is enriched in incompatible elements similar to that for enriched mid-oceanic ridge basalt (e.g. Endeavour Ridge) and does not contain residual amphibole. Thus, metasomatic enrichment most likely reflects small degree partial melts rather than hydrous fluids.

J. E. Dixon1, J. R. Filiberto1,4, J. G. Moore2 & C. J. Hickson3
1 Division of Marine Geology and Geophysics, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami FL 33149, USA jdixon@rsmas.miami.edu
2 US Geological Survey, MS-910, 345 Middlefield Road, Menlo Park, CA 94025, USA
3 Geological Survey of Canada, 101-605 Robson Street, Vancouver, British Columbia V6B 5J3, Canada
4 Department of Geosciences, SUNY, Stonybrook, NY 11794-2100, USA

Chloride ion sites in silicate and aluminosilicate glasses: A preliminary study by 35Cl solid-state NMR

admin — Mon, 08 Mar 2010 04:30:38 +0000

Despite the importance of the chloride ion in magmas and the fluids that separate from them, very little is known about atomic-scale structural environments for Cl– in silicate glasses. We present here the first solid-state 35Cl NMR data for Cl in silicate and aluminosilicate glasses, made possible by the availability of very high (14.1 to 18.8 Tesla) magnetic fields. We find that 35Cl has a wide range in chemical shifts that correlate well with cation-Cl distance and thus contain considerable structural information. In general, Cl is coordinated primarily by network-modifying alkali or alkaline earth cations, and we see no evidence for Al-Cl bonding.

Jonathan F. Stebbins* and Lin-Shu Du
Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305-2115, U.S.A.

Correspondence: * E-mail: stebbins@pangea.stanford.edu

Determination of molar absorptivities for infrared absorption bands of H2O in andesitic glasses

admin — Mon, 08 Mar 2010 04:29:31 +0000

We have determined infrared molar absorptivities for water absorption bands in Fe-bearing and Fe-free andesitic glasses. Water dissolves in andesitic glasses as both hydroxyl groups and molecular water as observed in other silicate glasses. Concentrations of molecular water and hydroxyl species are a strong function of total water content. IR molar absorptivities for Fe-bearing andesite are 3570 = 62.32 ± 0.42 L/mol·cm, 4500 = 0.79 ± 0.07 L/mol·cm, 5200 = 1.07 ± 0.07 L/mol·cm, and 1630 = 42.34 ± 2.77 L/mol·cm. Molar absorptivities for Fe-free andesite are 69.21 ± 0.52 L/mol·cm for 3570, 0.89 ± 0.07 L/mol·cm for 4500, 1.46 ± 0.07 L/mol·cm for 5200, and 52.05 ± 2.85 L/mol·cm for 1630. Molar absorptivities show significant compositional dependencies that can be predicted based on tetrahedral cation (Si+4, Al+3)/total cation fraction.
Charles W. Mandeville1,*, James D. Webster1, Malcolm J. Rutherford2, Bruce E. Taylor3, Adrian Timbal3 and Kevin Faure4
1 American Museum of of Natural History, Central Park West at 79th St. New York, New York 10024-5192, U.S.A.
2 Department of Geological Sciences, Brown University, Box 1846, Providence, Rhode Island 02912, U.S.A.
3 Geological Survey of Canada, 601 Booth Street, Ottawa, Ontario K1A0E8, Canada
4 Institute of Geological & Nuclear Sciences, 30 Gracefield Rd. Lower Hutt, New Zealand

Correspondence: * E-mail: cmandy@amnh.org