5,485 research outputs found

    Modular vector fields attached to Dwork family: sl2(C)\mathfrak{sl}_2(\mathbb{C}) Lie algebra

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    We introduce an algebraic group G\sf G that acts from right on the moduli space T\textsf{T} of Calabi-Yau nn-folds arising from Dwork family enhanced with differential forms, and describe its Lie algebra Lie(G){\rm Lie}({\sf G}). We observe that Lie(G){\rm Lie}({\sf G}) together with a modular vector field R{\sf R} on T\textsf{T} generates another Lie algebra G\mathfrak{G}, called AMSY-Lie algebra, such that dim⁑G=dim⁑T\dim \mathfrak{G}=\dim {\sf T}. We find sl2(C)\mathfrak{sl}_2(\mathbb{C}) as a Lie subalgebra of G\mathfrak{G} that contains R\sf R.Comment: 20 page

    WAMDII observation of an auroral atmosphere wave event

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    Field tests of WAMDII (Wide Angle Michelson Doppler Imaging Interferometer) on February 23 to 24, 1984 in Saskatoon produced wind images of the aurora that show well defined wave structures in lambda 5577. Wavelengths and velocities of these structures suggest an acoustic-gravity wave interpretation, but their short duration warrants their being termed an event. The Dopplergrams are presented with emphasis on the interpretation of the waves and a discussion of possible sources

    Simultaneous dual-element analyses of refractory metals in naturally occurring matrices using resonance ionization of sputtered atoms

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    The combination of secondary neutral mass spectrometry (SNMS) and resonance ionization spectroscopy (RIS) has been shown to be a powerful tool for the detection of low levels of elemental impurities in solids. Drawbacks of the technique have been the laser-repetition-rate-limited, low duty cycle of the analysis and the fact that RIS schemes are limited to determinations of a single element. These problems have been addressed as part of an ongoing program to explore the usefulness of RIS/SNMS instruments for the analysis of naturally occurring samples. Efficient two-color, two-photon (1+1) resonance ionization schemes were identified for Mo and for four platinum-group elements (Ru, Os, Ir, and Re). Careful selection of the ionization schemes allowed Mo or Ru to be measured simultaneously with Re, Os, or Ir, using two tunable dye lasers and an XeCl excimer laser. Resonance frequencies could be switched easily under computer control, so that all five elements can be rapidly analyzed. In situ measurements of these elements in metal grains from five meteorites were conducted. From the analyses, estimates of the precision and the detection limit of the instrument were made. The trade-off between lower detection limits and rapid multielement RIS analyses is discussed

    The solar oxygen-isotopic composition: Predictions and implications for solar nebula processes

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    The outer layers of the Sun are thought to preserve the average isotopic and chemical composition of the solar system. The solar O-isotopic composition is essentially unmeasured, though models based on variations in meteoritic materials yield several predictions. These predictions are reviewed and possible variations on these predictions are explored. In particular, the two-component mixing model of Clayton and Mayeda (1984) (slightly revised here) predicts solar compositions to lie along an extension of the calcium-aluminum-rich inclusion (CAI) ^(16)O line between (Ξ΄^(18)O, Ξ΄^(17)O) = (16.4, 11.4)%0 and (12.3, 7.5)%0. Consideration of data from ordinary chondrites suggests that the range of predicted solar composition should extend to slightly lower Ξ΄^(18)O values. The predicted solar composition is critically sensitive to the solid/gas ratio in the meteorite-forming region, which is often considered to be significantly enriched over solar composition. A factor of two solid/gas enrichment raises the predicted solar (Ξ΄^(18)O, Ξ΄^(17)O) values along an extension of the CAI ^(16)O line to (33, 28)%0. The model is also sensitive to the nebular O gas phase. If conversion of most of the gaseous O from CO to H_2O occurred at relatively low temperatures and was incomplete at the time of CM aqueous alteration, the predicted nebular gas composition (and hence the solar composition) would be isotopically heavier along a slope 1/2 line. The likelihood of having a single solid nebular O component is discussed. A distribution of initial solid compositions along the CAI ^(16)O line (rather than simply as an end-member) would not significantly change the predictions above in at least one scenario. Even considering these variations within the mixing model, the predicted range of solar compositions is distinct from that expected if the meteoritic variations are due to non-mass-dependent fractionation. Thus, a measurement of the solar O composition to a precision of several permil would clearly distinguish between these theories and should clarify a number of other important issues regarding solar system formation

    Brightness variations of the northern 630nm intertropical arc and the midnight pressure bulge over Eritrea

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    The nightglow brightness at 630nm from the thermospheric O(<sup>1</sup>D) layer was monitored nightly at Asmara, Eritrea (15.4° N, 39.9° E, 7° N dip) with an all-sky imager. Averages of north-south strips of the images enabled contour plots of brightness on a latitude vs. local time grid. The contours show the movement of the intertropical arc southward before midnight, staying just north of Asmara after midnight, and gradually brightening to a maximum at 02:00h local civil time, 02:00 LT, after which it disappears before dawn. It is argued that all features of the plots can be explained by known mechanisms capable of driving ions along magnetic field lines, including the fountain effect, summer to winter transequatorial winds, and the midnight pressure bulge. <P style="line-height: 20px;"> The 02:00 LT brightness maximum is the most striking and the most persistent feature in the data. The persistence of the location of the 02:00 LT brightening is attributed to a pressure bulge centered on the geographic equator at midnight and extending to higher latitudes with increasing local time in both the winter and the summer hemispheres. The bulge is shown to be stronger near solstice than near equinox, confirming earlier work

    Variations in solar wind fractionation as seen by ACE/SWICS over a solar cycle and the implications for Genesis Mission results

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    We use ACE/SWICS elemental composition data to compare the variations in solar wind fractionation as measured by SWICS during the last solar maximum (1999-2001), the solar minimum (2006-2009) and the period in which the Genesis spacecraft was collecting solar wind (late 2001 - early 2004). We differentiate our analysis in terms of solar wind regimes (i.e. originating from interstream or coronal hole flows, or coronal mass ejecta). Abundances are normalized to the low-FIP ion magnesium to uncover correlations that are not apparent when normalizing to high-FIP ions. We find that relative to magnesium, the other low-FIP elements are measurably fractionated, but the degree of fractionation does not vary significantly over the solar cycle. For the high-FIP ions, variation in fractionation over the solar cycle is significant: greatest for Ne/Mg and C/Mg, less so for O/Mg, and the least for He/Mg. When abundance ratios are examined as a function of solar wind speed, we find a strong correlation, with the remarkable observation that the degree of fractionation follows a mass-dependent trend. We discuss the implications for correcting the Genesis sample return results to photospheric abundances.Comment: Accepted for publication in Ap

    Solar Carbon Monoxide, Thermal Profiling, and the Abundances of C, O, and their Isotopes

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    A solar photospheric "thermal profiling" analysis is presented, exploiting the infrared rovibrational bands of carbon monoxide (CO) as observed with the McMath-Pierce Fourier transform spectrometer (FTS) at Kitt Peak, and from above the Earth's atmosphere by the Shuttle-borne ATMOS experiment. Visible continuum intensities and center-limb behavior constrained the temperature profile of the deep photosphere, while CO center-limb behavior defined the thermal structure at higher altitudes. The oxygen abundance was self consistently determined from weak CO absorptions. Our analysis was meant to complement recent studies based on 3-D convection models which, among other things, have revised the historical solar oxygen (and carbon) abundance downward by a factor of nearly two; although in fact our conclusions do not support such a revision. Based on various considerations, an oxygen abundance of 700+/-100 ppm (parts per million relative to hydrogen) is recommended; the large uncertainty reflects the model sensitivity of CO. New solar isotopic ratios also are reported for 13C, 17O, and 18O.Comment: 90 pages, 19 figures (some with parts "a", "b", etc.); to be published in the Astrophysical Journal Supplement

    Rey Auditory-Verbal Learning Test: Development of Norms for Healthy Young Adults

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    The Rey Auditory-Verbal Learning Test (AVLT) has been widely used in clinical neuropsychology because of the usefulness of its multiple measures of learning and memory and its ease of administration. Normative data has been reported for some patient populations but little normative data exists for healthy individuals. This study reports AVLT data for 222 job applicants, presently employed in a variety of occupations, who had previously passed basic-academic-skills tests and physical examinations and were motivated to perform well on AVLT testing. AVLT normative data are presented by WAIS-R FSIQ, Age, Education, and by Age and FSIQ combined. We also present a proposal for sharing and pooling data to expand the data matrix we present

    ΠŸΡ€ΠΈΠ½Ρ†ΠΈΠΏΡ‹ построСния ΠΈΠ½Ρ„ΠΎΡ€ΠΌΠ°Ρ†ΠΈΠΎΠ½Π½ΠΎΠΉ систСмы для планирования, согласования ΠΈ ΠΌΠΎΠ½ΠΈΡ‚ΠΎΡ€ΠΈΠ½Π³Π° Π³Π΅ΠΎΠ»ΠΎΠ³ΠΎ-тСхничСских мСроприятий

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    Описана ΠΏΡ€ΠΎΠ±Π»Π΅ΠΌΠ°Ρ‚ΠΈΠΊΠ° ΠΈ ΠΈΠ½Ρ„ΠΎΡ€ΠΌΠ°Ρ†ΠΈΠΎΠ½Π½Ρ‹Π΅ ΠΏΠΎΠ΄Ρ…ΠΎΠ΄Ρ‹, примСняСмыС Π°Π²Ρ‚ΠΎΡ€Π°ΠΌΠΈ ΠΏΡ€ΠΈ Ρ€Π΅ΡˆΠ΅Π½ΠΈΠΈ Π·Π°Π΄Π°Ρ‡ΠΈ вСдСния Π΅Π΄ΠΈΠ½ΠΎΠΉ Π±Π°Π·Ρ‹ Π΄Π°Π½Π½Ρ‹Ρ… Π³Π΅ΠΎΠ»ΠΎΠ³ΠΎ-тСхничСских мСроприятий, ΠΎΡ€Π³Π°Π½ΠΈΠ·Π°Ρ†ΠΈΠΈ совмСстного взаимодСйствия ΠΏΡ€ΠΎΠ΅ΠΊΡ‚Π½Ρ‹Ρ… ΠΏΠΎΠ΄Ρ€Π°Π·Π΄Π΅Π»Π΅Π½ΠΈΠΉ ΠΈ Π½Π΅Π΄Ρ€ΠΎΠΏΠΎΠ»ΡŒΠ·ΠΎΠ²Π°Ρ‚Π΅Π»Ρ ΠΏΡ€ΠΈ ΠΏΠ»Π°Π½ΠΈΡ€ΠΎΠ²Π°Π½ΠΈΠΈ, согласовании ΠΈ ΠΌΠΎΠ½ΠΈΡ‚ΠΎΡ€ΠΈΠ½Π³Π΅ Π³Π΅ΠΎΠ»ΠΎΠ³ΠΎ-тСхничСских мСроприятий
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