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UPPER LIMITS ON THE NUMBER OF SMALL BODIES IN SEDNA-LIKE ORBITS BY THE TAOS PROJECT
Wang, J.-H.,Lehner, M. J.,Zhang, Z.-W.,Bianco, F. B.,Alcock, C.,Chen, W.-P.,Axelrod, T.,Byun, Y.-I.,Coehlo, N. ,K.,Cook, K. H.,Dave, R.,de Pater, I.,Porrata, R.,Kim, D.-W.,King, S.-K.,Lee, T.,Lin, American Institute of Physics 2009 The Astronomical journal Vol.138 No.6
<P>We present the results of a search for occultation events by objects at distances between 100 and 1000 AU in light curves from the Taiwanese-American Occultation Survey. We searched for consecutive, shallow flux reductions in the stellar light curves obtained by our survey between 2005 February 7 and 2006 December 31 with a total of ~4.5 × 10<SUP>9</SUP> three-telescope simultaneous photometric measurements. No events were detected, allowing us to set upper limits on the number density as a function of size and distance of objects in Sedna-like orbits, using simple models.</P>
THE TAOS PROJECT: RESULTS FROM SEVEN YEARS OF SURVEY DATA
Zhang, Z.-W.,Lehner, M. J.,Wang, J.-H.,Wen, C.-Y.,Wang, S.-Y.,King, S.-K.,Granados, Á,. P.,Alcock, C.,Axelrod, T.,Bianco, F. B.,Byun, Y.-I.,Chen, W. P.,Coehlo, N. K.,Cook, K. H.,de Pater, I.,Kim American Institute of Physics 2013 The Astronomical journal Vol.146 No.1
<P>The Taiwanese-American Occultation Survey (TAOS) aims to detect serendipitous occultations of stars by small (~1 km diameter) objects in the Kuiper Belt and beyond. Such events are very rare (<10<SUP>–3</SUP> events per star per year) and short in duration (~200 ms), so many stars must be monitored at a high readout cadence. TAOS monitors typically ~500 stars simultaneously at a 5 Hz readout cadence with four telescopes located at Lulin Observatory in central Taiwan. In this paper, we report the results of the search for small Kuiper Belt objects (KBOs) in seven years of data. No occultation events were found, resulting in a 95% c.l. upper limit on the slope of the faint end of the KBO size distribution of q = 3.34-3.82, depending on the surface density at the break in the size distribution at a diameter of about 90 km.</P>
Bianco, F. B.,Zhang, Z.-W.,Lehner, M. J.,Mondal, S.,King, S.-K.,Giammarco, J.,Holman, M. J.,Coehlo, N. ,K.,Wang, J.-H.,Alcock, C.,Axelrod, T.,Byun, Y.-I.,Chen, W. P.,Cook, K. H.,Dave, R.,de Pater, American Institute of Physics 2010 The Astronomical journal Vol.139 No.4
<P>We have analyzed the first 3.75 years of data from the Taiwanese American Occultation Survey (TAOS). TAOS monitors bright stars to search for occultations by Kuiper Belt objects (KBOs). This data set comprises 5 × 10<SUP>5</SUP> star hours of multi-telescope photometric data taken at 4 or 5 Hz. No events consistent with KBO occultations were found in this data set. We compute the number of events expected for the Kuiper Belt formation and evolution models of Pan & Sari, Kenyon & Bromley, Benavidez & Campo Bagatin, and Fraser. A comparison with the upper limits we derive from our data constrains the parameter space of these models. This is the first detailed comparison of models of the KBO size distribution with data from an occultation survey. Our results suggest that the KBO population is composed of objects with low internal strength and that planetary migration played a role in the shaping of the size distribution.</P>
Kim, D.-W.,Protopapas, P.,Alcock, C.,Byun, Y.-I.,Kyeong, J.,Lee, B.-C.,Wright, N. J.,Axelrod, T.,Bianco, F. B.,Chen, W.-P.,Coehlo, N. K.,Cook, K. H.,Dave, R.,King, S.-K.,Lee, T.,Lehner, M. J.,Lin, H.- American Institute of Physics 2010 The Astronomical journal Vol.139 No.2
<P>We analyzed data accumulated during 2005 and 2006 by the Taiwan-American Occultation Survey (TAOS) in order to detect short-period variable stars (periods of <img entity='lsim' SRC='http://ej.iop.org/icons/Entities/lsim.gif' ALT='lsim' ALIGN='BASELINE' />1 hr) such as δ Scuti. TAOS is designed for the detection of stellar occultation by small-size Kuiper Belt Objects and is operating four 50 cm telescopes at an effective cadence of 5 Hz. The four telescopes simultaneously monitor the same patch of the sky in order to reduce false positives. To detect short-period variables, we used the fast Fourier transform algorithm (FFT) in as much as the data points in TAOS light curves are evenly spaced. Using FFT, we found 41 short-period variables with amplitudes smaller than a few hundredths of a magnitude and periods of about an hour, which suggest that they are low-amplitude δ Scuti stars. The light curves of TAOS δ Scuti stars are accessible online at the Time Series Center Web site (http://timemachine.iic.harvard.edu).</P>
Mondal, S.,Lin, C. C.,Chen, W. P.,Zhang, Z.-W.,Alcock, C.,Axelrod, T.,Bianco, F. B.,Byun, Y.-I.,Coehlo, N. K.,Cook, K. H.,Dave, R.,Kim, D.-W.,King, S.-K.,Lee, T.,Lehner, M. J.,Lin, H.-C.,Marshall, S. American Institute of Physics 2010 The Astronomical journal Vol.139 No.5
<P>The Taiwanese-American Occultation Survey (TAOS) project has collected more than a billion photometric measurements since 2005 January. These sky survey data—covering timescales from a fraction of a second to a few hundred days—are a useful source to study stellar variability. A total of 167 star fields, mostly along the ecliptic plane, have been selected for photometric monitoring with the TAOS telescopes. This paper presents our initial analysis of a search for periodic variable stars from the time-series TAOS data on one particular TAOS field, No. 151 (R.A. = 17<SUP>h</SUP>30<SUP>m</SUP>6<img entity='fs' SRC='http://ej.iop.org/icons/Entities/fs.gif' ALT='fs' ALIGN='BASELINE' />7, decl. = 27°17'30'', J2000), which had been observed over 47 epochs in 2005. A total of 81 candidate variables are identified in the 3 deg<SUP>2</SUP> field, with magnitudes in the range 8 < R < 16. On the basis of the periodicity and shape of the light curves, 29 variables, 15 of which were previously unknown, are classified as RR Lyrae, Cepheid, δ Scuti, SX Phonencis, semi-regular, and eclipsing binaries.</P>
Preparation of ferroelectric nanoparticles for their use in liquid crystalline colloids
Atkuri, H,Cook, G,Evans, D R,Cheon, C-I,Glushchenko, A,Reshetnyak, V,Reznikov, Yu,West, J,Zhang, K Institute of Physics Publishing in association wit 2009 Journal of optics A, Pure and applied optics Vol.11 No.2
<P>In this paper we summarize our many years of experience in the preparation and optimization of stable colloids of ferroelectric nanoparticles dispersed in an isotropic carrier and in a liquid crystal host. The colloids are of interest for use in electro-optic devices, photorefractive hybrids and nonlinear optical elements. We also outline some of the most interesting features the nanoparticles bring to liquid crystals, along with the potential of these relatively new colloids.</P>
Park, K.W.,Serrano, L.A.,Ahn, S.,Baek, M.H.,Wiles, A.A.,Cooke, G.,Hong, J. Pergamon Press 2017 Tetrahedron Vol.73 No.8
Three 'D-π-A-π-A' based dyes have been synthesized featuring MeO-, MeS- and Me<SUB>2</SUB>N- as donor residues and benzothiadiazole and cyanoacrylic acid residues as acceptor units. UV-vis spectroscopy, solution electrochemistry and DFT modelling indicated that the Me<SUB>2</SUB>N- residue has the most significant effect on optical and redox properties of a photosensitizer. DSSCs with the Me<SUB>2</SUB>N- functionalized dye gave the highest power conversion efficiency of the series (η = 5.61%), presumably due to the better donor ability of this unit, which promotes more effective intramolecular charge transfer (ICT) characteristics.
DAZL is essential for stress granule formation implicated in germ cell survival upon heat stress
Kim, B.,Cooke, H. J.,Rhee, K. The Company of Biologists 2012 Development (Cambridge) Vol.139 No.3
<P>Mammalian male germ cells should be maintained below body temperature for proper development. Here, we investigated how male germ cells respond to heat stress. A short exposure of mouse testes to core body temperature induced phosphorylation of eIF2α and the formation of stress granules (SGs) in male germ cells. We observed that DAZL, a germ cell-specific translational regulator, was translocated to SGs upon heat stress. Furthermore, SG assembly activity was significantly diminished in the early male germ cells of Dazl-knockout mice. The DAZL-containing SGs played a protective role against heat stress-induced apoptosis by the sequestration of specific signaling molecules, such as RACK1, and the subsequent blockage of the apoptotic MAPK pathway. Based on these results, we propose that DAZL is an essential component of the SGs, which prevent male germ cells from undergoing apoptosis upon heat stress.</P>
MASSES AND ORBITAL CONSTRAINTS FOR THE OGLE-2006-BLG-109Lb,c JUPITER/SATURN ANALOG PLANETARY SYSTEM
Bennett, D. P.,Rhie, S. H.,Nikolaev, S.,Gaudi, B. S.,Udalski, A.,Gould, A.,Christie, G. W.,Maoz, D.,Dong, S.,McCormick, J.,Szymań,ski, M. K.,Tristram, P. J.,Macintosh, B.,Cook, K. H.,Kubiak, M.,P IOP Publishing 2010 The Astrophysical journal Vol.713 No.2
<P>We present a new analysis of the Jupiter+Saturn analog system, OGLE-2006-BLG-109Lb,c, which was the first double planet system discovered with the gravitational microlensing method. This is the only multi-planet system discovered by any method with measured masses for the star and both planets. In addition to the signatures of two planets, this event also exhibits a microlensing parallax signature and finite source effects that provide a direct measure of the masses of the star and planets, and the expected brightness of the host star is confirmed by Keck AO imaging, yielding masses of M(*) = 0.51(-0.04)(+0.05) M(circle dot), M(b) = 231 +/- 19 M(circle plus), and M(c) = 86 +/- 7 M(circle plus). The Saturn-analog planet in this system had a planetary light-curve deviation that lasted for 11 days, and as a result, the effects of the orbital motion are visible in the microlensing light curve. We find that four of the six orbital parameters are tightly constrained and that a fifth parameter, the orbital acceleration, is weakly constrained. No orbital information is available for the Jupiter-analog planet, but its presence helps to constrain the orbital motion of the Saturn-analog planet. Assuming co-planar orbits, we find an orbital eccentricity of epsilon = 0.15(-0.10) (+0.17) and an orbital inclination of i = 64 degrees(+ 4 degrees)(-7 degrees) The 95% confidence level lower limit on the inclination of i > 49 degrees implies that this planetary system can be detected and studied via radial velocity measurements using a telescope of greater than or similar to 30 m aperture.</P>