Standards for electron probe microanalysis of silicates prepared by convenient method

Standard compositions suitable for electron probe microanalysis of various silicates are prepared by coprecipitation of specified salts with colloidal silica to form a gel which is decomposed into a powdered oxide mixture and compressed into thin pellets. These pellets of predetermined standard are compared with a silicate sample to determine its composition

Early Childhood Expulsions and Suspensions Undermine Our Nation's Most Promising Agent of Opportunity and Social Justice

This brief presents the latest information regarding early childhood expulsions and suspensions with a special emphasis on how continuing gender and race disparities violate the civil rights of many of our youngest learners and contribute to our nation's costly achievement gap by locking our boys and African-American children out of educational opportunities and diminishing the ability of early education to provide the social justice remedy it was designed to produce

Volatilization-fractionation of silicates related to chondrite composition

The compositions of chondritic meteorites are linked to the solar composition. It is believed that the chemistry of the (generally) drop-shaped chondrules which comprise a large portion of these meteorites may present valuable clues to their formation and, ultimately, to the early conditions and processes of the planets. The purpose of this experiment is to determine the nature of volatilization-fractionation of silicate (and related metallic) compositions related to chondrite composition

Mantle plumes on Venus revisited

The Equatorial Highlands of Venus consist of a series of quasicircular regions of high topography, rising up to about 5 km above the mean planetary radius. These highlands are strongly correlated with positive geoid anomalies, with a peak amplitude of 120 m at Atla Regio. Shield volcanism is observed at Beta, Eistla, Bell, and Atla Regiones and in the Hathor Mons-Innini Mons-Ushas Mons region of the southern hemisphere. Volcanos have also been mapped in Phoebe Regio and flood volcanism is observed in Ovda and Thetis Regiones. Extensional tectonism is also observed in Ovda and Thetis Regiones. Extensional tectonism is also observed in many of these regions. It is now widely accepted that at least Beta, Atla, Eistla, and Bell Regiones are the surface expressions of hot, rising mantel plumes. Upwelling plumes are consistent with both the volcanism and the extensional tectonism observed in these regions. The geoid anomalies and topography of these four regions show considerable variation. Peak geoid anomalies exceed 90 m at Beta and Atla, but are only 40 m at Eistla and 24 m at Bell. Similarly, the peak topography is greater at Beta and Atla than at Eistla and Bell. Such a range of values is not surprising because terrestrial hotspot swells also have a side range of geoid anomalies and topographic uplifts. Kiefer and Hager used cylindrical axisymmetric, steady-state convection calculations to show that mantle plumes can quantitatively account for both the amplitude and the shape of the long-wavelength geoid and topography at Beta and Atla. In these models, most of the topography of these highlands is due to uplift by the vertical normal stress associated with the rising plume. Additional topography may also be present due to crustal thickening by volcanism and crustal thinning by rifting. Smrekar and Phillips have also considered the geoid and topography of plumes on Venus, but they restricted themselves to considering only the geoid-topography ratio and did not examine either the geoid and topography amplitudes separately or the shapes of anomalies

Entangled maximal mixings in U_PMNS=U_l^dagger U_nu, and a connection to complex mass textures

We discuss two different configurations of U_PMNS=U_l^dagger U_nu with maximal mixings in both U_l and U_nu. The non-maximal mixing angles are assumed to be small, which means that they can be expanded in. Since we are particularly interested in the implications for CP violation, we fully take into account complex phases. We demonstrate that one possibility leads to intrinsically large theta_13 and strong deviations from maximal mixings. The other possibility is generically close to tri-bimaximal mixing, and allows for large CP violation. We demonstrate how the determination of the theta_23 octant and the precision measurement of delta_CP could discriminate among different qualitative sub-cases. In order to constrain the unphysical and observable phases even further, we relate our configurations to complex mass matrix textures. In particular, we focus on phase patterns which could be generated by powers of a single complex quantity eta=theta_C exp(i Phi), which can be motivated by Froggatt-Nielsen-like models. For example, it turns out that in all of the discussed cases, one of the Majorana phases is proportional to Phi to leading order. In the entire study, we encounter three different classes of sum rules, which we systematically classify.Comment: 27 pages, 6 tables, 1 figure. Shortened version to appear in Phys. Rev.

CO2 per se activates carbon dioxide receptors.

Carbon dioxide has been used in traps for more than six decades to monitor mosquito populations and help make informed vector management decisions. CO2 is sensed by gustatory receptors (GRs) housed in neurons in the maxillary palps. CO2-sensitive GRs have been identified from the vinegar fly and mosquitoes, but it remains to be resolved whether these receptors respond to CO2 or bicarbonate. As opposed to the vinegar fly, mosquitoes have three GR subunits, but it is assumed that subunits GR1 and GR3 form functional receptors. In our attempt to identify the chemical species that bind these receptors, we discovered that GR2 and GR3 are essential for receptor function and that GR1 appears to function as a modulator. While Xenopus oocytes coexpressing Culex quinquefasciatus subunits CquiGR1/3 and CquiGR1/2 were not activated, CquiGR2/3 gave robust responses to sodium bicarbonate. Interestingly, CquiGR1/2/3-coexpressing oocytes gave significantly lower responses. That the ternary combination is markedly less sensitive than the GR2/GR3 combination was also observed with orthologs from the yellow fever and the malaria mosquito. By comparing responses of CquiGR2/CquiGR3-coexpressing oocytes to sodium bicarbonate samples (with or without acidification) and measuring the concentration of aqueous CO2, we showed that there is a direct correlation between dissolved CO2 and receptor response. We then concluded that subunits GR2 and GR3 are essential for these carbon dioxide-sensitive receptors and that they are activated by CO2 per se, not bicarbonate