Letters between O. T. Geckeler and W. J. Kerr

Letters concerning a position in the mathematics department at Utah Agricultural College as well as a booklet describing O. T. Geckeler\u27s education

Promoting Partnerships for Student Success: Lessons from the SSPIRE Initiative

The Student Support Partnership Integrating Resources and Education (SSPIRE) initiative aimed to increase the success of young, low-income, and academically underprepared California community college students by helping colleges strengthen their support services and better integrate these services with academic instruction. This report describes what the nine participating community colleges did to meet the goals of SSPIRE and offers lessons for other institutions drawn from MDRC's research on the initiative

Transfer of autocollimator calibration for use with scanning gantry profilometers for accurate determination of surface slope and curvature of state of the art x ray mirrors

X ray optics, desired for beamlines at free electron laser and diffraction limited storage ring x ray light sources, must have almost perfect surfaces, capable of delivering light to experiments without significant degradation of brightness and coherence. To accurately characterize such optics at an optical metrology lab, two basic types of surface slope profilometers are used the long trace profilers LTPs and nanometer optical measuring NOM like angular deflectometers, based on electronic autocollimator AC ELCOMAT 3000. The inherent systematic errors of the instrument s optical sensors set the principle limit to their measuring performance. Where autocollimator of a NOM like profiler may be calibrated at a unique dedicated facility, this is for a particular configuration of distance, aperture size, and angular range that does not always match the exact use in a scanning measurement with the profiler. Here we discuss the developed methodology, experimental set up, and numerical methods of transferring the calibration of one reference AC to the scanning AC of the Optical Surface Measuring System OSMS , recently brought to operation at the ALS Xray Optics Laboratory. We show that precision calibration of the OSMS performed in three steps, allows us to provide high confidence and accuracy low spatial frequency metrology and not print into measurements the inherent systematic error of tool in use. With the examples of the OSMS measurements with a state of the art x ray aspherical mirror, available from one of the most advanced vendors of X ray optics, we demonstrate the high efficacy of the developed calibration procedure. The results of our work are important for obtaining high reliability data, needed for sophisticated numerical simulations of beamline performance and optimization of beamline usage of the optics. This work was supported by the U. S. Department of Energy under contract number DE AC02 05CH1123

Detection of orbital and superhump periods in Nova V2574 Ophiuchi (2004)

We present the results of 37 nights of CCD unfiltered photometry of nova V2574 Oph (2004) from 2004 and 2005. We find two periods of 0.14164 d (~3.40 h) and 0.14773 d (~3.55 h) in the 2005 data. The 2004 data show variability on a similar timescale, but no coherent periodicity was found. We suggest that the longer periodicity is the orbital period of the underlying binary system and that the shorter period represents a negative superhump. The 3.40 h period is about 4% shorter than the orbital period and obeys the relation between superhump period deficit and binary period. The detection of superhumps in the light curve is evidence of the presence of a precessing accretion disk in this binary system shortly after the nova outburst. From the maximum magnitude - rate of decline relation, we estimate the decay rate t_2 = 17+/-4 d and a maximum absolute visual magnitude of M_Vmax = -7.7+/-1.7 mag.Comment: 6 pages, 6 figures, 2 .sty files, AJ accepted, minor change to one of reference

An alternative model of the magnetic cataclysmic variable V1432 Aquilae (=RX J1940.1-1025)

V1432 Aql is currently considered to be an asynchronous AM Her type system, with an orbital period of 12116.3 s and a spin period of 12150 s. I present an alternative model in which V1432 Aql is an intermediate polar with disk overflow or diskless accretion geometry, with a spin period near 4040 s. I argue that published data are insufficient to distinguish between the two models; instead, I provide a series of predictions of the two models that can be tested against future observations.Comment: 10 pages LaTeX including 3 Postscript Figures, to be published in Ap

Ontology: Use and abuse

The final publication is available at Springer via http://dx.doi.org/110.1007/978-3-540-79860-6_2Revised Selected Papers of 5th International Workshop, AMR 2007, Paris, France, July 5-6, 2007This paper is a critical analysis of the use of ontology as an instrument to specify the semantics of a document. The paper argue that not only is a logic of the type used in ontology insufficient for such a purpose, but that the very idea that meaning is a property of a document that can be expressed and stored independently of the interpretation activity is misguided. The paper proposes, in very general lines, a possible alternative view of meaning as modification of context and shows that many current approaches to meaning, from ontology to emergent semantics, can be seen as spacial cases of this approach, and can be analyzed from a very general theoretical framework

Carbon nanotubes: are they dispersed or dissolved in liquids?

Carbon nanotubes (CNTs) constitute a novel class of nanomaterials with remarkable applications in diverse domains. However, the main intrincsic problem of CNTs is their insolubility or very poor solubility in most of the common solvents. The basic key question here is: are carbon nanotubes dissolved or dispersed in liquids, specifically in water? When analyzing the scientific research articles published in various leading journals, we found that many researchers confused between "dispersion" and "solubilization" and use the terms interchangeably, particularly when stating the interaction of CNTs with liquids. In this article, we address this fundamental issue to give basic insight specifically to the researchers who are working with CNTs as well asgenerally to scientists who deal with nano-related research domains

Time-Resolved HST Spectroscopy of Four Eclipsing Magnetic Cataclysmic Variables

Time-resolved HST UV eclipse spectrophotometry is presented for the magnetic CVs V1309 Ori, MN Hya, V2301 Oph, and V1432 Aql. Separation of the light curves into wavebands allows the multiple emission components to be distinguished. Photospheric hot spots are detected in V1309 Ori and V2301 Oph. The emission- line spectra of V1309 Ori and MN Hya are unusual, with the strength of N V 1240 and N IV 1718 suggesting an overabundance of nitrogen. Three epochs of observation of the asynchronous V1432 Aql cover ~1/3 of a 50-day lap cycle between the white dwarf spin and binary orbit. The light curves vary from epoch to epoch and as a function of waveband. The dereddened UV spectrum is extremely bright and the spectral energy distribution coupled with the duration of eclipse ingress indicate that the dominant source of energy is a hot (T~35,000K) white dwarf. Undiminished line emission through eclipse indicates that the eclipse is caused by the accretion stream, not the secondary star. The hot white dwarf, combined with its current asynchronous nature and rapid timescale for relocking, suggests that V1432 Aql underwent a nova eruption in the past 75-150 yr. The reversed sense of asynchronism, with the primary star currently spinning up toward synchronism, is not necessarily at odds with this scenario, if the rotation of the magnetic white dwarf can couple to the ejecta during the wind phase of the eruption.Comment: To appear in ApJ Part 1; 25 pages, 12 figure

X-Ray Emission and Optical Polarization of V1432 Aquilae: An Asynchronous Polar

A detailed analysis of X-ray data from ROSAT, ASCA, XMM and RXTE for the asynchronous polar V1432 Aql along with Stokes polarimetry data from SAAO, is presented. Power spectra from long-baseline ROSAT data show a spin period of 12150s along with several system related frequency components. However, the second harmonic of the spin period dominates power spectrum in the XMM data. For the optical circular polarization, the dominant period corresponds to half the spin period. The ROSAT data can be explained as due to accretion onto two hot spots that are not anti-podal. The variations seen in the optical polarization and the ASCA and XMM data suggest the presence of at least three accretion foot prints on the white dwarf surface. Two spectral models, a multi-temperature plasma and a photo-ionized plasma model, are used for spectral study. The RXTE PCA data are used to constrain the white dwarf mass to 1.2$\pm$0.1 M_odot using the multi-temperature plasma model. A strong soft X-ray excess (<0.8 keV) in the XMM MOS data is well modeled by a blackbody component having a temperature of 80-90 eV. The plasma emission lines seen at 6.7 and 7.0 keV are well fitted using the multi-temperature plasma model, however an additional Gaussian is needed for the 6.4 keV line. The multi-temperature plasma model requires a homogeneous absorber fully covering the source and a partial absorber covering 65% of the source. The photo-ionized plasma model, with a range of Fe column densities, gives a slightly better overall fit and fits all emission lines. The presence of a strong blackbody component, a spin period of 12150s, modulation of the 6.4 keV line flux with spin period, and a very hard X-ray component suggest that V1432 Aql is a polar with X-ray spectral properties similar to that of a soft intermediate polar.Comment: 46 pages, including 13 figures and 4 tables, To appear in The Astrophysical Journal, 20 May 2005 issue, vol. 625, Added Report-no and Journal-ref, no change in the text of the pape