WorldWideScience

Sample records for diurnal photometric variability

  1. Photometric variability in earthshine observations.

    Science.gov (United States)

    Langford, Sally V; Wyithe, J Stuart B; Turner, Edwin L

    2009-04-01

    The identification of an extrasolar planet as Earth-like will depend on the detection of atmospheric signatures or surface non-uniformities. In this paper we present spatially unresolved flux light curves of Earth for the purpose of studying a prototype extrasolar terrestrial planet. Our monitoring of the photometric variability of earthshine revealed changes of up to 23% per hour in the brightness of Earth's scattered light at around 600 nm, due to the removal of specular reflection from the view of the Moon. This variability is accompanied by reddening of the spectrum and results from a change in surface properties across the continental boundary between the Indian Ocean and Africa's east coast. Our results based on earthshine monitoring indicate that specular reflection should provide a useful tool in determining the presence of liquid water on extrasolar planets via photometric observations.

  2. Photometric Variability in the Faint Sky Variability Survey

    NARCIS (Netherlands)

    Morales-Rueda, L.; Groot, P.J.; Augusteijn, T.; Nelemans, G.A.; Vreeswijk, P.M.; Besselaar, E.J.M. van den

    2005-01-01

    The Faint Sky Variability Survey (FSVS) is aimed at finding photometric and/or astrometric variable objects between 16th and 24th mag on time-scales between tens of minutes and years with photometric precisions ranging from 3 millimag to 0.2 mag. An area of ~23 deg2, located at mid and

  3. Photometric Variability of the Be Star Population

    Energy Technology Data Exchange (ETDEWEB)

    Labadie-Bartz, Jonathan; Pepper, Joshua; McSwain, M. Virginia [Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem, PA 18015 (United States); Bjorkman, J. E.; Bjorkman, K. S. [Ritter Observatory, Department of Physics and Astronomy, University of Toledo, 2801 W. Bancroft, Toledo, OH 43606-3390 (United States); Lund, Michael B.; Rodriguez, Joseph E.; Stassun, Keivan G. [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States); Stevens, Daniel J. [Department of Astronomy, The Ohio State University, 140 W. 18th Avenue, Columbus, OH 43210 (United States); James, David J. [Cerro Tololo Inter-American Observatory, Casilla 603 La Serena (Chile); Kuhn, Rudolf B. [Southern African Large Telescope, P.O. Box 9, Observatory 7935, Cape Town (South Africa); Siverd, Robert J. [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Santa Barbara, CA 93117 (United States); Beatty, Thomas G. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States)

    2017-06-01

    Be stars have generally been characterized by the emission lines in their spectra, and especially the time variability of those spectroscopic features. They are known to also exhibit photometric variability at multiple timescales, but have not been broadly compared and analyzed by that behavior. We have taken advantage of the advent of wide-field, long-baseline, and high-cadence photometric surveys that search for transiting exoplanets to perform a comprehensive analysis of brightness variations among a large number of known Be stars. The photometric data comes from the KELT transit survey, with a typical cadence of 30 minutes, a baseline of up to 10 years, photometric precision of about 1%, and coverage of about 60% of the sky. We analyze KELT light curves of 610 known Be stars in both the northern and southern hemispheres in an effort to study their variability. Consistent with other studies of Be star variability, we find most of the stars to be photometrically variable. We derive lower limits on the fraction of stars in our sample that exhibit features consistent with non-radial pulsations (25%), outbursts (36%), and long-term trends in the circumstellar disk (37%), and show how these are correlated with spectral sub-types. Other types of variability, such as those owing to binarity, are also explored. Simultaneous spectroscopy for some of these systems from the Be Star Spectra database allow us to better understand the physical causes for the observed variability, especially in cases of outbursts and changes in the disk.

  4. Photometric Variability of the Be Star Population

    International Nuclear Information System (INIS)

    Labadie-Bartz, Jonathan; Pepper, Joshua; McSwain, M. Virginia; Bjorkman, J. E.; Bjorkman, K. S.; Lund, Michael B.; Rodriguez, Joseph E.; Stassun, Keivan G.; Stevens, Daniel J.; James, David J.; Kuhn, Rudolf B.; Siverd, Robert J.; Beatty, Thomas G.

    2017-01-01

    Be stars have generally been characterized by the emission lines in their spectra, and especially the time variability of those spectroscopic features. They are known to also exhibit photometric variability at multiple timescales, but have not been broadly compared and analyzed by that behavior. We have taken advantage of the advent of wide-field, long-baseline, and high-cadence photometric surveys that search for transiting exoplanets to perform a comprehensive analysis of brightness variations among a large number of known Be stars. The photometric data comes from the KELT transit survey, with a typical cadence of 30 minutes, a baseline of up to 10 years, photometric precision of about 1%, and coverage of about 60% of the sky. We analyze KELT light curves of 610 known Be stars in both the northern and southern hemispheres in an effort to study their variability. Consistent with other studies of Be star variability, we find most of the stars to be photometrically variable. We derive lower limits on the fraction of stars in our sample that exhibit features consistent with non-radial pulsations (25%), outbursts (36%), and long-term trends in the circumstellar disk (37%), and show how these are correlated with spectral sub-types. Other types of variability, such as those owing to binarity, are also explored. Simultaneous spectroscopy for some of these systems from the Be Star Spectra database allow us to better understand the physical causes for the observed variability, especially in cases of outbursts and changes in the disk.

  5. UV Reconstruction Algorithm And Diurnal Cycle Variability

    Science.gov (United States)

    Curylo, Aleksander; Litynska, Zenobia; Krzyscin, Janusz; Bogdanska, Barbara

    2009-03-01

    UV reconstruction is a method of estimation of surface UV with the use of available actinometrical and aerological measurements. UV reconstruction is necessary for the study of long-term UV change. A typical series of UV measurements is not longer than 15 years, which is too short for trend estimation. The essential problem in the reconstruction algorithm is the good parameterization of clouds. In our previous algorithm we used an empirical relation between Cloud Modification Factor (CMF) in global radiation and CMF in UV. The CMF is defined as the ratio between measured and modelled irradiances. Clear sky irradiance was calculated with a solar radiative transfer model. In the proposed algorithm, the time variability of global radiation during the diurnal cycle is used as an additional source of information. For elaborating an improved reconstruction algorithm relevant data from Legionowo [52.4 N, 21.0 E, 96 m a.s.l], Poland were collected with the following instruments: NILU-UV multi channel radiometer, Kipp&Zonen pyranometer, radiosonde profiles of ozone, humidity and temperature. The proposed algorithm has been used for reconstruction of UV at four Polish sites: Mikolajki, Kolobrzeg, Warszawa-Bielany and Zakopane since the early 1960s. Krzyscin's reconstruction of total ozone has been used in the calculations.

  6. A PHOTOMETRICALLY AND MORPHOLOGICALLY VARIABLE INFRARED NEBULA IN L483

    International Nuclear Information System (INIS)

    Connelley, Michael S.; Hodapp, Klaus W.; Fuller, Gary A.

    2009-01-01

    We present narrow and broad K-band observations of the Class 0/I source IRAS 18148-0440 that span 17 years. The infrared nebula associated with this protostar in the L483 dark cloud is both morphologically and photometrically variable on a timescale of only a few months. This nebula appears to be an infrared analog to other well known optically visible variable nebulae associated with young stars, such as Hubble's Variable Nebula. Along with Cepheus A, this is one of the first large variable nebulae to be found that is only visible in the infrared. The variability of this nebula is most likely due to changing illumination of the cloud rather than any motion of the structure in the nebula. Both morphological and photometric changes are observed on a timescale only a few times longer than the light crossing time of the nebula, suggesting very rapid intrinsic changes in the illumination of the nebula. Our narrowband observations also found that H 2 knots are found nearly twice as far to the east of the source as to its west, and that H 2 emission extends farther east of the source than the previously known CO outflow.

  7. Heliospheric Modulation of Galactic Cosmic Rays; Diurnal Variability Abstract Details

    Science.gov (United States)

    Kalu, D. F.; Okpala, K. C.

    2017-12-01

    We have studied the variability of Cosmic rays flux during solar quiet days at mid and high latitudes in the Northern Hemisphere. By using the five (5) quietest days for each month and the five disturbed days for each month, the monthly mean diurnal variation of cosmic ray anisotropy have been derived for the period 1999-2015, which covers part of cycles 23, and cycle 24. This study seeks to understand the heliospheric contribution to the variation of these Cosmic rays on quietest days, three stations (Inuvik, Moscow, Rome) Neutron Monitors were employed. This study seeks to understand the important features of the high latitude and mid latitude diurnal wave, and how solar and geomagnetic activity may be influencing the wave characteristics. Cosmic ray wave characteristics were obtained by discrete Fourier transform (DFT). The mean, diurnal amplitude, phase and dispersion for each month's diurnal wave were calculated and profiled. There was clear indication that the terrestrial effect on the variability of the monthly mean was more associated with geomagnetic activity rather than rigidity of the cosmic rays. Correlation of the time series of these wave characteristic with solar and geomagnetic activity index showed better association with solar activity.

  8. Interannual and Intraseasonal Variability of the Diurnal Tide

    Science.gov (United States)

    Riggin, D. M.; Ortland, D. A.; Lieberman, R. S.; Oberheide, J.; Murayama, Y.; Hocking, W. K.; Vincent, R. A.; Reid, I. M.; Kumar, G. K.; Batista, P. P.; Clemesha, B. R.

    2013-12-01

    Temporal variations in the amplitude of the diurnal tide (DT) have been observed by radars with a seasonal dependence that is typically semiannual in the tropics. During some years the wind variation departs from the normal seasonal behavior with anomalously large amplitudes compared to most other years. This anomaly often takes the form of a greatly enhanced boreal spring equinoctal maximum. The boreal spring of 2008 is a example of this behavior. Diurnal amplitudes in the meridional winds are shown in the figure below for the first 6 months of 2008. Note that the diurnal tide undergoes a sharp increase in amplitude up to 80 ms-1 during this event. The characteristics of this event are diagnosed in a variety of global data sets. These include our own physics-based assimilation of SABER temperatures, and gridded analyses from the national weather services (NCAR/NCEP and ECMWF). Tidal amplitude variations are sometimes attributed to nonlinear interaction. However, this type of interaction would be expected to produce non-migrating tides, e.g., westward-2 or standing. SABER data show that the amplitude anomaly is mainly in the migrating DT. The global data sets allow us to explore properties of the anomaly, such as its origin, evolution in time, and associated momentum flux. In addition to this case study, we also investigate the general characteristics of DT interannual variability during the years of the SABER mission (2002-present). Diurnal tide momentum deposition plays a significant role in controlling the zonal mean wind in the mesosphere, We demonstrate its importance in driving the mesospheric semiannual oscillation (MSAO). Diurnal tide wind amplitudes in the meridional component observed at two radar sites, Rarotonga, Cook Islands (22.1°S, 159.8°W), and at Guanacaste, Costa Rica (10.3°N, 85.6°W).

  9. Modelling the diurnal variability of SST and its vertical extent

    DEFF Research Database (Denmark)

    Karagali, Ioanna; Høyer, Jacob L.; Donlon, Craig J.

    2014-01-01

    of the water column where most of the heat is absorbed and where the exchange of heat and momentum with the atmosphere occurs. During day-time and under favourable conditions of low winds and high insolation, diurnal warming of the upper layer poses challenges for validating and calibrating satellite sensors......Sea Surface Temperature (SST) is a key variable in air-sea interactions, partly controlling the oceanic uptake of CO2 and the heat exchange between the ocean and the atmosphere, amongst others. Satellite SSTs are representative of skin and sub-skin temperature, i.e. in the upper millimetres...... and merging SST time series. When radiometer signals, typically from satellites, are validated with in situ measurements from drifting and moored buoys a general mismatch is found, associated with the different reference depth of each type of measurement. A generally preferred approach to bridge the gap...

  10. Classical variables in the era of space photometric missions

    Directory of Open Access Journals (Sweden)

    Molnár L.

    2015-01-01

    Full Text Available The space photometric missions like CoRoT and Kepler transformed our view of pulsating stars, including the well-known RR Lyrae and Cepheid classes. The K2, TESS and PLATO missions will expand these investigations to larger sample sizes and to specific stellar populations.

  11. Diurnal variability of Synechococcus abundance in Sagami Bay, Japan

    Digital Repository Service at National Institute of Oceanography (India)

    Mitbavkar, S.; Saino, T.

    Synechococcus, the most dominant picophytoplankton in coastal regions, exhibits diurnal variations in the open ocean. The aim of this study was to assess its short-term population dynamics and cell cycle phases through DNA analysis in a coastal...

  12. SST diurnal variability in the North Sea and the Baltic Sea

    DEFF Research Database (Denmark)

    Karagali, Ioanna; Høyer, Jacob; Hasager, Charlotte Bay

    2012-01-01

    (σ) between 0.4K and 0.9K. The 5year record with daytime temperature anomalies is used to derive robust statistical description of duration, spatial extent, proximity to coast and water depth of the diurnal warming events. Seasonal and inter-annual variations in the diurnal warming are also...... quantified. Daytime anomalies exceeding 2K are identified during the spring and summer months of every year, peaking at 1500 LT. Events with daily anomalies exceeding 5K are observed. Areas where diurnal variability is often observed coincide with areas of frequently observed low winds and turbid waters...

  13. Search for relation between flares and photometric variability outside of flares in EV Lac

    International Nuclear Information System (INIS)

    Rojzman, G.Sh.

    1984-01-01

    The observations of the flare star EV Lac in July-September 1981 have confirmed the existence of photometric variability outside the flares during the night. It was found that, as a rule, a slow increase of brightness in U and B bands during 1-2 hours preceded the flares. It is suggested that the variability outside the flares is the result of the variability of chpomospheric emission lines and continuum that are emitted by the chromospheric preflare formations

  14. Stellar variability and its implications for photometric planet detection with Kepler

    Science.gov (United States)

    Batalha, N. M.; Jenkins, J.; Basri, G. S.; Borucki, W. J.; Koch, D. G.

    2002-01-01

    Kepler is one of three candidates for the next NASA Discovery Mission and will survey the extended solar neighborhood to detect and characterize hundreds of terrestrial (and larger) planets in or near the habitable zone. Its strength lies in its ability to detect large numbers of Earth-sized planets - planets which produced a 10-4 change in relative stellar brightness during a transit across the disk of a sun-like parent star. Such a detection requires high instrumental relative precision and is facilitated by observing stars which are photometrically quiet on hourly timescales. Probing stellar variability across the HR diagram, one finds that many of the photometrically quietest stars are the F and G dwarfs. The Hipparcos photometric database shows the lowest photometric variances among stars of this spectral class. Our own Sun is a prime example with RMS variations over a few rotational cycles of typically (3 - 4)×10-4 (computed from VIRGO/DIARAD data taken Jan-Mar 2001). And variability on the hourly time scales crucial for planet detection is significantly smaller: just (2 - 5)×10-5. This bodes well for planet detection programs such as Kepler and Eddington. With significant numbers of photometrically quiet solar-type stars, Earth-sized planets should be readily identified provided they are abundant in the solar neighborhood. In support of the Kepler science objectives, we have initiated a study of stellar variability and its implications for planet detection. Herein, we summarize existing observational and theoretrical work with the objective of determining the percentage of stars in the Kepler field of view expected to be photometrically stable at a level which allows for Earth-sized planet detection.

  15. COMPARISON OF KEPLER PHOTOMETRIC VARIABILITY WITH THE SUN ON DIFFERENT TIMESCALES

    International Nuclear Information System (INIS)

    Basri, Gibor; Walkowicz, Lucianne M.; Reiners, Ansgar

    2013-01-01

    We utilize Kepler data to study the precision differential photometric variability of solar-type and cooler stars at different timescales, ranging from half an hour to three months. We define a diagnostic that characterizes the median differential intensity change between data bins of a given timescale. We apply the same diagnostics to Solar and Heliospheric Observatory data that has been rendered comparable to Kepler. The Sun exhibits similar photometric variability on all timescales as comparable solar-type stars in the Kepler field. The previously defined photometric ''range'' serves as our activity proxy (driven by starspot coverage). We revisit the fraction of comparable stars in the Kepler field that are more active than the Sun. The exact active fraction depends on what is meant by ''more active than the Sun'' and on the magnitude limit of the sample of stars considered. This active fraction is between a quarter and a third (depending on the timescale). We argue that a reliable result requires timescales of half a day or longer and stars brighter than M Kep of 14, otherwise non-stellar noise distorts it. We also analyze main sequence stars grouped by temperature from 6500 to 3500 K. As one moves to cooler stars, the active fraction of stars becomes steadily larger (greater than 90% for early M dwarfs). The Sun is a good photometric model at all timescales for those cooler stars that have long-term variability within the span of solar variability.

  16. Optical photometric variability of 2S 0114+65

    Science.gov (United States)

    Taylor, M.; Finley, J. P.; Kurt, C.; Koenigsberger, G.

    1995-01-01

    In this paper we present Johnson V photometry of the Be/x-ray binary star system 2S 0114+65. Although this star exhibits periodic variations in x-rays, optical studies have failed to reveal fluctuations greater than 5 millimag. The data presented in this paper provide the first evidence for periodic optical variability in 2S 0114+65. On each of four nights in October 1993, we find low amplitude variations with a period of 2.77 +/- 0.48 h and with a semiamplitude of 4 millimag. This period is in good agreement with results of a comprehensive study of the x-ray data. We explore the possibility that this period represents the pulsational period of the B-star primary and the possibility that it is the rotational period of the neutron star. If the latter is the correct interpretation, we calculate a spin-up time scale of 5 x 10(exp 5) yr.

  17. Photometric variability of the SS 433 (V 1343 Aq1) in 1979-1981

    International Nuclear Information System (INIS)

    Gladyshev, S.A.; Goranskij, V.P.; Cherepashchuk, A.M.

    1983-01-01

    Results of photometric observations of SS 433 carried out in 1981 are presented, the 164-day and 13-day variability of this ob ect being confirmed. All available photometric observations of SS 433 during 1979-1981 are summarized in order to investigate main regularities in brightness variability. Using the photometric data of three years the precessing period of 164sup(d)+-1sup(d) is determined. The orbital period is 13sup(d).086+-0sup(d).006. The maximum of the uneclipsed brightness of SS 433 is observed at the moment of maximum separation of ''relativistic'' emission lines. At this moment the orbital brightness curve is most similar to that of #betta# Lyr-type eclipsing variables. The amplitude of the orbital 13-day variability is minimal near the moments of coincidence of relativistic emissions (''cross-over'' dates). New observational data confirm the model of SS 433 as a massive eclipsing binary with a ''slaved'' bright accretion disk

  18. Computing the Polarimetric and Photometric Variability of Be Stars

    Science.gov (United States)

    Marr, K. C.; Jones, C. E.; Halonen, R. J.

    2018-01-01

    We investigate variations in the linear polarization as well as in the V-band and B-band color–magnitudes for classical Be star disks. We present two models: disks with enhanced disk density and disks that are tilted or warped from the stellar equatorial plane. In both cases, we predict variation in observable properties of the system as the disk rotates. We use a non-LTE radiative transfer code BEDISK (Sigut & Jones) in combination with a Monte Carlo routine that includes multiple scattering (Halonen et al.) to model classical Be star systems. We find that a disk with an enhanced density region that is one order of magnitude denser than the disk’s base density shows as much as ∼ 0.2 % variability in the polarization while the polarization position angle varies by ∼ 8^\\circ . The ΔV magnitude for the same system shows variations of up to ∼ 0.4 mag while the Δ(B–V) color varies by at most ∼ 0.01 mag. We find that disks tilted from the equatorial plane at small angles of ∼ 30^\\circ more strongly reflect the values of polarization and color–magnitudes reported in the literature than disks tilted at larger angles. For this model, the linear polarization varies by ∼ 0.3 % , the polarization position angle varies by ∼ 60^\\circ , the ΔV magnitude varies up to 0.35 mag, and the Δ(B–V) color varies by up to 0.1 mag. We find that the enhanced disk density models show ranges of polarization and color–magnitudes that are commensurate with what is reported in the literature for all sizes of the density-enhanced regions. From this, we cannot determine any preference for small or large density-enhanced regions.

  19. Confirming LBV Candidates Through Variability: A Photometric and Spectroscopic Monitoring Study

    Science.gov (United States)

    Stringfellow, Guy; Gvaramadze, Vasilii

    2013-02-01

    Luminous Blue Variable (LBV) stars represent an extremely rare class of luminous massive stars with high mass loss rates. The paucity ( 12) of confirmed Galactic LBV precludes determining a solid evolutionary connection between LBV and other intermediate (e.g. Ofpe/WN9, WNL) phases in the life of very massive stars. We've been conducting an optical/near-IR spectral survey of a large subset of central stars residing within newly discovered it Spitzer nebulae and have identified over two dozen new candidate LBVs (cLBVs) based on spectral similarity alone; confirming them as bona fide LBVs requires demonstrating 1-3 mag photometric and spectroscopic variability. This marks a significant advancement in the study of massive stars, far outweighing the return from many studies searching for LBVs and WRs the past several decades. Monitoring from semesters 2011B-2012A already has confirmed one new cLBV as a bona fide LBV. We propose to continue optical-IR photometric monitoring of these cLBVS with the 1.3m. Chiron, replacing the RC spectrograph on the 1.5m, now allows high-resolution optical spectroscopic monitoring of bright cLBVs, 11 of which are proposed herein. Spectra are important for understanding the physics driving photometric variability, properties of the wind, and allow analysis of line profiles.

  20. ESA STSE “SST Diurnal Variability: Regional Extend - Implications in Atmospheric Modelling”

    DEFF Research Database (Denmark)

    Karagali, Ioanna

    The diurnal variability of SST, driven by the coincident occurrence of low enough wind and solar heating, has been observed in various regions of the global ocean [4, 5, 6]. Atmospheric, oceanic and climate models are not adequately resolving the daily SST cycle, resulting in biases of the total...

  1. Diurnal variability of surface fluxes at an oceanic station in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Sarma, Y.V.B.; Rao, D.P.

    Diurnal variability of the surface fluxes and ocean heat content was studied using the time-series data on marine surface meteorological parameters and upper ocean temperature collected at an oceanic station in the Bay of Bengal during 1st to 8th...

  2. Diurnal variability of inner-shelf circulation in the lee of a cape under upwelling conditions

    Science.gov (United States)

    Lamas, L.; Peliz, A.; Dias, J.; Oliveira, P. B.; Angélico, M. M.; Castro, J. J.; Fernandes, J. N.; Trindade, A.; Cruz, T.

    2017-07-01

    The nearshore circulation in the lee of a cape under upwelling conditions was studied using in-situ data from 3 consecutive summers (2006-2008). Focus was given to a period between 20 July and 04 August 2006 to study the diurnal variability of the cross-shelf circulation. This period was chosen because it had a steady upwelling-favourable wind condition modulated by a diurnal cycle much similar to sea breeze. The daily variability of the observed cross-shelf circulation consisted of three distinct periods: a morning period with a 3-layer vertical structure with onshore velocities at mid-depth, a mid-day period where the flow is reversed and has a 2-layer structure with onshore velocities at the surface and offshore flow below, and, lastly, in the evening, a 2-layer period with intensified offshore velocities at the surface and onshore flow at the bottom. The observed cross-shelf circulation showed a peculiar vertical shape and diurnal variability different from several other systems described in literature. We hypothesize that the flow reversal of the cross-shelf circulation results as a response to the rapid change of the wind magnitude and direction at mid-day with the presence of the cape north of the mooring site influencing this response. A numerical modelling experiment exclusively forced by winds simulated successfully most of the circulation at the ADCP site, especially the mid-day reversal and the evening's upwelling-type structure. This supports the hypothesis that the cross-shelf circulation at diurnal timescales is mostly wind-driven. By analysing the 3D circulation in the vicinity of Cape Sines we came to the conclusion that the diurnal variability of the wind and the flow interaction with topography are responsible for the circulation variability at the ADCP site, though only a small region in the south of the cape showed a similar diurnal variability. The fact that the wind diurnally undergoes relaxation and intensification strongly affects the

  3. SPECTROSCOPIC AND PHOTOMETRIC VARIABILITY IN THE A0 SUPERGIANT HR 1040

    International Nuclear Information System (INIS)

    Corliss, David J.; Morrison, Nancy D.; Adelman, Saul J.

    2015-01-01

    A time-series analysis of spectroscopic and photometric observables of the A0 Ia supergiant HR 1040 has been performed, including equivalent widths, radial velocities, and Strömgren photometric indices. The data, obtained from 1993 through 2007, include 152 spectroscopic observations from the Ritter Observatory 1 m telescope and 269 Strömgren photometric observations from the Four College Automated Photoelectric Telescope. Typical of late B- and early A-type supergiants, HR 1040 has a highly variable Hα profile. The star was found to have an intermittent active phase marked by correlation between the Hα absorption equivalent width and blue-edge radial velocity and by photospheric connections observed in correlations to equivalent width, second moment and radial velocity in Si ii λλ6347, 6371. High-velocity absorption (HVA) events were observed only during this active phase. HVA events in the wind were preceded by photospheric activity, including Si ii radial velocity oscillations 19–42 days prior to onset of an HVA event and correlated increases in Si ii W λ and second moment from 13 to 23 days before the start of the HVA event. While increases in various line equivalent widths in the wind prior to HVA events have been reported in the past in other stars, our finding of precursors in enhanced radial velocity variations in the wind and at the photosphere is a new result

  4. Analysis of optically variable devices using a photometric light-field approach

    Science.gov (United States)

    Soukup, Daniel; Å tolc, Svorad; Huber-Mörk, Reinhold

    2015-03-01

    Diffractive Optically Variable Image Devices (DOVIDs), sometimes loosely referred to as holograms, are popular security features for protecting banknotes, ID cards, or other security documents. Inspection, authentication, as well as forensic analysis of these security features are still demanding tasks requiring special hardware tools and expert knowledge. Existing equipment for such analyses is based either on a microscopic analysis of the grating structure or a point-wise projection and recording of the diffraction patterns. We investigated approaches for an examination of DOVID security features based on sampling the Bidirectional Reflectance Distribution Function (BRDF) of DOVIDs using photometric stereo- and light-field-based methods. Our approach is demonstrated on the practical task of automated discrimination between genuine and counterfeited DOVIDs on banknotes. For this purpose, we propose a tailored feature descriptor which is robust against several expected sources of inaccuracy but still specific enough for the given task. The suggested approach is analyzed from both theoretical as well as practical viewpoints and w.r.t. analysis based on photometric stereo and light fields. We show that especially the photometric method provides a reliable and robust tool for revealing DOVID behavior and authenticity.

  5. The central star candidate of the planetary nebula Sh2-71: photometric and spectroscopic variability

    Science.gov (United States)

    Močnik, T.; Lloyd, M.; Pollacco, D.; Street, R. A.

    2015-07-01

    We present the analysis of several newly obtained and archived photometric and spectroscopic data sets of the intriguing and yet poorly understood 13.5 mag central star candidate of the bipolar planetary nebula Sh2-71. Photometric observations confirmed the previously determined quasi-sinusoidal light curve with a period of 68 d and also indicated periodic sharp brightness dips, possibly eclipses, with a period of 17.2 d. In addition, the comparison between U and V light curves revealed that the 68 d brightness variations are accompanied by a variable reddening effect of ΔE(U - V) = 0.38. Spectroscopic data sets demonstrated pronounced variations in spectral profiles of Balmer, helium and singly ionized metal lines and indicated that these variations occur on a time-scale of a few days. The most accurate verification to date revealed that spectral variability is not correlated with the 68 d brightness variations. The mean radial velocity of the observed star was measured to be ˜26 km s-1 with an amplitude of ±40 km s-1. The spectral type was determined to be B8V through spectral comparison with synthetic and standard spectra. The newly proposed model for the central star candidate is a Be binary with a misaligned precessing disc.

  6. DISCOVERY OF A WOLF-RAYET STAR THROUGH DETECTION OF ITS PHOTOMETRIC VARIABILITY

    Energy Technology Data Exchange (ETDEWEB)

    Littlefield, Colin [Law School, University of Notre Dame, Notre Dame, IN 46556 (United States); Garnavich, Peter; McClelland, Colin; Rettig, Terrence [Physics Department, University of Notre Dame, Notre Dame, IN 46556 (United States); Marion, G. H. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Vinko, Jozsef [Department of Optics, University of Szeged (Hungary); Wheeler, J. Craig [Astronomy Department, University of Texas, Austin, TX 78712 (United States)

    2012-06-15

    We report the serendipitous discovery of a heavily reddened Wolf-Rayet star that we name WR 142b. While photometrically monitoring a cataclysmic variable, we detected weak variability in a nearby field star. Low-resolution spectroscopy revealed a strong emission line at 7100 A, suggesting an unusual object and prompting further study. A spectrum taken with the Hobby-Eberly Telescope confirms strong He II emission and an N IV 7112 A line consistent with a nitrogen-rich Wolf-Rayet star of spectral class WN6. Analysis of the He II line strengths reveals no detectable hydrogen in WR 142b. A blue-sensitive spectrum obtained with the Large Binocular Telescope shows no evidence for a hot companion star. The continuum shape and emission line ratios imply a reddening of E(B - V) = 2.2-2.6 mag. We estimate that the distance to WR 142b is 1.4 {+-} 0.3 kpc.

  7. A SEARCH FOR PHOTOMETRIC VARIABILITY IN L- AND T-TYPE BROWN DWARF ATMOSPHERES

    International Nuclear Information System (INIS)

    Khandrika, Harish; Burgasser, Adam J.; Melis, Carl; Luk, Christopher; Bowsher, Emily; Swift, Brandon

    2013-01-01

    Using the Gemini infrared camera on the 3 m Shane telescope at Lick Observatory, we have searched for broadband J and K' photometric variability for a sample of 15 L- and T-type brown dwarfs, including 7 suspected spectral binaries. Four of the dwarfs—2MASS J0939–2448, 2MASS J1416+1348A, 2MASS J1711+2232, and 2MASS J2139+0220—exhibit statistically significant variations over timescales ranging from ∼0.5 hr to 6 days. Our detection of variability in 2MASS J2139+0220 confirms that reported by Radigan et al., and periodogram and phase dispersion minimization analysis also confirms a variability period of approximately 7.6 ± 0.2 hr. Remarkably, two of the four variables are known or candidate binary systems, including 2MASS J2139+0220, for which we find only marginal evidence of radial velocity variation over the course of a year. This result suggests that some spectral binary candidates may appear as such due to the blending of cloudy and non-cloudy regions in a single ''patchy'' atmosphere. Our results are consistent with an overall variability fraction of 35% ± 5%, with no clear evidence of greater variability among brown dwarfs at the L dwarf/T dwarf transition.

  8. Optical photometric variable stars towards the Galactic H II region NGC 2282

    Science.gov (United States)

    Dutta, Somnath; Mondal, Soumen; Joshi, Santosh; Jose, Jessy; Das, Ramkrishna; Ghosh, Supriyo

    2018-05-01

    We report here CCD I-band time series photometry of a young (2-5 Myr) cluster NGC 2282, in order to identify and understand the variability of pre-main-sequence (PMS) stars. The I-band photometry, down to ˜20.5 mag, enables us to probe the variability towards the lower mass end (˜0.1 M⊙) of PMS stars. From the light curves of 1627 stars, we identified 62 new photometric variable candidates. Their association with the region was established from H α emission and infrared (IR) excess. Among 62 variables, 30 young variables exhibit H α emission, near-IR (NIR)/mid-IR (MIR) excess or both and are candidate members of the cluster. Out of 62 variables, 41 are periodic variables, with a rotation rate ranging from 0.2-7 d. The period distribution exhibits a median period at ˜1 d, as in many young clusters (e.g. NGC 2264, ONC, etc.), but it follows a unimodal distribution, unlike others that have bimodality, with slow rotators peaking at ˜6-8 d. To investigate the rotation-disc and variability-disc connection, we derived the NIR excess from Δ(I - K) and the MIR excess from Spitzer [3.6]-[4.5] μm data. No conclusive evidence of slow rotation with the presence of discs around stars and fast rotation for discless stars is obtained from our periodic variables. A clear increasing trend of the variability amplitude with IR excess is found for all variables.

  9. Diurnal and seasonal DOC and POC variability in the land-locked sea

    Directory of Open Access Journals (Sweden)

    Beata Szymczycha

    2017-07-01

    Full Text Available Organic matter is a minor yet important component of the marine environment. The aim of this study was to investigate the diurnal and seasonal changes in dissolved and particulate organic carbon (DOC and POC, respectively. Thus, DOC and POC as well as chlorophyll a (Chl a, δ13C, NO3−, NO2−, NH4+, PO43−, salinity, pH, and temperature were regularly measured in samples collected for 24 h (2-h resolution in the Gdańsk Deep (54°44.730′N, 19°08.531′E at three water depths (1, 10, and 40 m during sampling campaigns in 2011 (May, 2014 (May, and 2015 (January, March, May, July, September, November. Seasonal variations in DOC and POC followed the seasonality of Chl a (proportional trend and nutrients (reverse trend concentrations. Diurnal oscillations were detected in six out of the eight measurement series. The strongest diurnal variability in both POC and DOC occurred in May 2011 and March 2015, when phytoplankton activity was highest (high Chl a. The surprisingly low δ13C values (range: −28‰ to −24‰ measured over the course of the study revealed the gaps in our knowledge of the isotopic characteristics of terrestrial- vs. marine-derived particulate organic matter.

  10. Pruning The ELM Survey: Characterizing Candidate Low-mass White Dwarfs through Photometric Variability

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Keaton J.; Winget, D. E.; Montgomery, M. H.; Castanheira, B. G.; Vanderbosch, Z.; Winget, K. I. [Department of Astronomy, University of Texas at Austin, Austin, TX 78712 (United States); Gianninas, A.; Kilic, Mukremin [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States); Hermes, J. J. [Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599 (United States); Brown, Warren R., E-mail: keatonb@astro.as.utexas.edu [Smithsonian Astrophysical Observatory, Cambridge, MA 02138 (United States)

    2017-02-01

    We assess the photometric variability of nine stars with spectroscopic T {sub eff} and log g values from the ELM Survey that locates them near the empirical extremely low-mass (ELM) white dwarf instability strip. We discover three new pulsating stars: SDSS J135512.34+195645.4, SDSS J173521.69+213440.6, and SDSS J213907.42+222708.9. However, these are among the few ELM Survey objects that do not show radial velocity (RV) variations that confirm the binary nature expected of helium-core white dwarfs. The dominant 4.31 hr pulsation in SDSS J135512.34+195645.4 far exceeds the theoretical cut-off for surface reflection in a white dwarf, and this target is likely a high-amplitude δ Scuti pulsator with an overestimated surface gravity. We estimate the probability to be less than 0.0008 that the lack of measured RV variations in four of eight other pulsating candidate ELM white dwarfs could be due to low orbital inclination. Two other targets exhibit variability as photometric binaries. Partial coverage of the 19.342 hr orbit of WD J030818.19+514011.5 reveals deep eclipses that imply a primary radius >0.4 R {sub ⊙}—too large to be consistent with an ELM white dwarf. The only object for which our time series photometry adds support to ELM white dwarf classification is SDSS J105435.78−212155.9, which has consistent signatures of Doppler beaming and ellipsoidal variations. We conclude that the ELM Survey contains multiple false positives from another stellar population at T {sub eff}≲9000 K, possibly related to the sdA stars recently reported from SDSS spectra.

  11. A MODEL FOR (QUASI-)PERIODIC MULTIWAVELENGTH PHOTOMETRIC VARIABILITY IN YOUNG STELLAR OBJECTS

    Energy Technology Data Exchange (ETDEWEB)

    Kesseli, Aurora Y. [Boston University, 725 Commonwealth Ave, Boston, MA 02215 (United States); Petkova, Maya A.; Wood, Kenneth; Gregory, Scott G. [SUPA, School of Physics and Astronomy, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9AD (United Kingdom); Whitney, Barbara A. [Department of Astronomy, University of Wisconsin-Madison, 475 N. Charter St, Madison, WI 53706 (United States); Hillenbrand, L. A. [Astronomy Department, California Institute of Technology, Pasadena, CA 91125 (United States); Stauffer, J. R.; Morales-Calderon, M.; Rebull, L. [Spitzer Science Center, California Institute of Technology, CA 91125 (United States); Alencar, S. H. P., E-mail: aurorak@bu.com [Departamento de Física—ICEx—UFMG, Av. Antônio Carlos, 6627, 30270-901, Belo Horizonte, MG (Brazil)

    2016-09-01

    We present radiation transfer models of rotating young stellar objects (YSOs) with hot spots in their atmospheres, inner disk warps, and other three-dimensional effects in the nearby circumstellar environment. Our models are based on the geometry expected from magneto-accretion theory, where material moving inward in the disk flows along magnetic field lines to the star and creates stellar hot spots upon impact. Due to rotation of the star and magnetosphere, the disk is variably illuminated. We compare our model light curves to data from the Spitzer YSOVAR project to determine if these processes can explain the variability observed at optical and mid-infrared wavelengths in young stars. We focus on those variables exhibiting “dipper” behavior that may be periodic, quasi-periodic, or aperiodic. We find that the stellar hot-spot size and temperature affects the optical and near-infrared light curves, while the shape and vertical extent of the inner disk warp affects the mid-IR light curve variations. Clumpy disk distributions with non-uniform fractal density structure produce more stochastic light curves. We conclude that magneto-accretion theory is consistent with certain aspects of the multiwavelength photometric variability exhibited by low-mass YSOs. More detailed modeling of individual sources can be used to better determine the stellar hot-spot and inner disk geometries of particular sources.

  12. Observing Seasonal and Diurnal Hydrometeorological Variability Within a Tropical Alpine Valley: Implications for Evapotranspiration

    Science.gov (United States)

    Hellstrom, R. A.; Mark, B. G.

    2007-12-01

    Conditions of glacier recession in the seasonally dry tropical Peruvian Andes motivate research to better constrain the hydrological balance in alpine valleys. There is an outstanding need to better understand the impact of the pronounced tropical hygric seasonality on energy and water budgets within pro-glacial valleys that channel glacier runoff to stream flow. This paper presents a novel embedded network installed in the glacierized Llanganuco valley of the Cordillera Blanca (9°S) comprising eight low-cost, discrete temperature and humidity microloggers ranging from 3470 to 4740 masl and an automatic weather station at 3850 masl. Data are aggregated into distinct dry and wet periods sampled from two full annual cycles (2004-2006) to explore patterns of diurnal and seasonal variability. The magnitude of diurnal solar radiation varies little within the valley between the dry and wet periods, while wet season near-surface air temperatures are cooler. Seasonally characteristic diurnal fluctuations in lapse rate partially regulate convection and humidity. Steep lapse rates during the wet season afternoon promote up-slope convection of warm, moist air and nocturnal rainfall events. Standardized grass reference evapotranspiration (ET0) was estimated using the FAO-56 algorithm of the United Nations Food and Agriculture Organization and compared with estimates of actual ET from the process-based BROOK90 model that incorporates more realistic vegetation parameters. Comparisons of composite diurnal cycles of ET for the wet and dry periods suggest about twice the daily ET0 during the dry period, attributed primarily to the 500% higher vapor pressure deficit and 20% higher daily total solar irradiance. Conversely, the near absence of rainfall during the dry season diminishes actual ET below that of the wet season by two orders of magnitude. Nearly cloud-free daylight conditions are critical for ET during the wet season. We found significant variability of ET with elevation

  13. Seasonal and diurnal variability of N{sub 2}O emissions from a full-scale municipal wastewater treatment plant

    Energy Technology Data Exchange (ETDEWEB)

    Daelman, Matthijs R.J., E-mail: m.r.j.daelman@tudelft.nl [Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft (Netherlands); Department of Biosystems engineering, Ghent University, Coupure links 653, 9000 Gent (Belgium); Voorthuizen, Ellen M. van [Royal HaskoningDHV, P.O. Box 151, 6500AD Nijmegen (Netherlands); Dongen, Udo G.J.M. van [Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft (Netherlands); Volcke, Eveline I.P. [Department of Biosystems engineering, Ghent University, Coupure links 653, 9000 Gent (Belgium); Loosdrecht, Mark C.M. van [Department of Biotechnology, Delft University of Technology, Julianalaan 67, 2628 BC Delft (Netherlands)

    2015-12-01

    During nitrogen removal in conventional activated sludge processes, nitrous oxide can be emitted. With a global warming potential of 298 CO{sub 2}-equivalents it is an important greenhouse gas that affects the sustainability of wastewater treatment. The present study reports nitrous oxide emission data from a 16 month monitoring campaign on a full-scale municipal wastewater treatment. The emission demonstrated a pronounced diurnal and seasonal variability. This variability was compared with the variability of a number of process variables that are commonly available on a municipal wastewater treatment plant. On a seasonal timescale, the occurrence of peaks in the nitrite concentration correlated strongly with the emission. The diurnal trend of the emission coincided with the diurnal trend of the nitrite and nitrate concentrations in the tank, suggesting that suboptimal oxygen concentrations may induce the production of nitrous oxide during both nitrification and denitrification. This study documents an unprecedented dataset that could serve as a reference for further research. - Highlights: • Unique dataset of long-term nitrous oxide emission from activated sludge tanks • Emission exhibited pronounced diurnal variability, superimposed on seasonal trend • Seasonal nitrous oxide emission trend correlated with daily nitrite peaks • Emission’s diurnal trend suggests suboptimal oxygen concentrations as cause.

  14. THE LICK AGN MONITORING PROJECT: PHOTOMETRIC LIGHT CURVES AND OPTICAL VARIABILITY CHARACTERISTICS

    International Nuclear Information System (INIS)

    Walsh, Jonelle L.; Bentz, Misty C.; Barth, Aaron J.; Minezaki, Takeo; Sakata, Yu; Yoshii, Yuzuru; Baliber, Nairn; Bennert, Vardha Nicola; Street, Rachel A.; Treu, Tommaso; Li Weidong; Filippenko, Alexei V.; Stern, Daniel; Brown, Timothy M.; Canalizo, Gabriela; Gates, Elinor L.; Greene, Jenny E.; Malkan, Matthew A.; Woo, Jong-Hak

    2009-01-01

    The Lick AGN Monitoring Project targeted 13 nearby Seyfert 1 galaxies with the intent of measuring the masses of their central black holes using reverberation mapping. The sample includes 12 galaxies selected to have black holes with masses roughly in the range 10 6 -10 7 M sun , as well as the well-studied active galactic nucleus (AGN) NGC 5548. In conjunction with a spectroscopic monitoring campaign, we obtained broadband B and V images on most nights from 2008 February through 2008 May. The imaging observations were carried out by four telescopes: the 0.76 m Katzman Automatic Imaging Telescope, the 2 m Multicolor Active Galactic Nuclei Monitoring telescope, the Palomar 60 inch (1.5 m) telescope, and the 0.80 m Tenagra II telescope. Having well-sampled light curves over the course of a few months is useful for obtaining the broad-line reverberation lag and black hole mass, and also allows us to examine the characteristics of the continuum variability. In this paper, we discuss the observational methods and the photometric measurements, and present the AGN continuum light curves. We measure various variability characteristics of each of the light curves. We do not detect any evidence for a time lag between the B- and V-band variations, and we do not find significant color variations for the AGNs in our sample.

  15. DISCOVERY OF A WOLF-RAYET STAR THROUGH DETECTION OF ITS PHOTOMETRIC VARIABILITY

    International Nuclear Information System (INIS)

    Littlefield, Colin; Garnavich, Peter; McClelland, Colin; Rettig, Terrence; Marion, G. H.; Vinkó, József; Wheeler, J. Craig

    2012-01-01

    We report the serendipitous discovery of a heavily reddened Wolf-Rayet star that we name WR 142b. While photometrically monitoring a cataclysmic variable, we detected weak variability in a nearby field star. Low-resolution spectroscopy revealed a strong emission line at 7100 Å, suggesting an unusual object and prompting further study. A spectrum taken with the Hobby-Eberly Telescope confirms strong He II emission and an N IV 7112 Å line consistent with a nitrogen-rich Wolf-Rayet star of spectral class WN6. Analysis of the He II line strengths reveals no detectable hydrogen in WR 142b. A blue-sensitive spectrum obtained with the Large Binocular Telescope shows no evidence for a hot companion star. The continuum shape and emission line ratios imply a reddening of E(B – V) = 2.2-2.6 mag. We estimate that the distance to WR 142b is 1.4 ± 0.3 kpc.

  16. The effect of the number of consecutive night shifts on diurnal rhythms in cortisol, melatonin and heart rate variability (HRV)

    DEFF Research Database (Denmark)

    Jensen, Marie Aarrebo; Garde, Anne Helene; Kristiansen, Jesper

    2016-01-01

    PURPOSE: The purpose of this review is to summarize the current knowledge from field studies on how many consecutive night shifts are required for adaptation of diurnal rhythms in cortisol, melatonin and heart rate variability (HRV) to night work. METHODS: A systematic search of the databases Pub...... recordings for HRV. Most of the studies in the review were small studies with less than 30 participants, and most studies evaluated diurnal rhythms after only two consecutive night shifts whereas only six studies used seven or more consecutive night shifts. The majority of studies found that adaptation...... to night work had not occurred after two consecutive night shifts, whereas a small number found evidence for full adaptation after seven consecutive night shifts based on diurnal rhythms in cortisol and melatonin. CONCLUSION: There are methodological differences in the field studies analyzing diurnal...

  17. A PHOTOMETRIC VARIABILITY SURVEY OF FIELD K AND M DWARF STARS WITH HATNet

    International Nuclear Information System (INIS)

    Hartman, J. D.; Bakos, G. A.; Noyes, R. W.; Sipocz, B.; Pal, A.; Kovacs, G.; Mazeh, T.; Shporer, A.

    2011-01-01

    Using light curves from the HATNet survey for transiting extrasolar planets we investigate the optical broadband photometric variability of a sample of 27, 560 field K and M dwarfs selected by color and proper motion (V - K ∼> 3.0, μ > 30 mas yr -1 , plus additional cuts in J - H versus H - K S and on the reduced proper motion). We search the light curves for periodic variations and for large-amplitude, long-duration flare events. A total of 2120 stars exhibit potential variability, including 95 stars with eclipses and 60 stars with flares. Based on a visual inspection of these light curves and an automated blending classification, we select 1568 stars, including 78 eclipsing binaries (EBs), as secure variable star detections that are not obvious blends. We estimate that a further ∼26% of these stars may be blends with fainter variables, though most of these blends are likely to be among the hotter stars in our sample. We find that only 38 of the 1568 stars, including five of the EBs, have previously been identified as variables or are blended with previously identified variables. One of the newly identified EBs is 1RXS J154727.5+450803, a known P = 3.55 day, late M-dwarf SB2 system, for which we derive preliminary estimates for the component masses and radii of M 1 = M 2 = 0.258 ± 0.008 M sun and R 1 = R 2 = 0.289 ± 0.007 R sun . The radii of the component stars are larger than theoretical expectations if the system is older than ∼200 Myr. The majority of the variables are heavily spotted BY Dra-type stars for which we determine rotation periods. Using this sample, we investigate the relations between period, color, age, and activity measures, including optical flaring, for K and M dwarfs, finding that many of the well-established relations for F, G, and K dwarfs continue into the M dwarf regime. We find that the fraction of stars that is variable with peak-to-peak amplitudes greater than 0.01 mag increases exponentially with the V - K S color such that

  18. Diurnal variability of CO2 flux at coastal zone of Taiwan based on eddy covariance observation

    Science.gov (United States)

    Chien, Hwa; Zhong, Yao-Zhao; Yang, Kang-Hung; Cheng, Hao-Yuan

    2018-06-01

    In this study, we employed shore-based eddy covariance systems for a continuous measurement of the coastal CO2 flux near the northwestern coast of Taiwan from 2011 to 2015. To ensure the validity of the analysis, the data was selected and filtered with a footprint model and an empirical mode decomposition method. The results indicate that the nearshore air-sea and air-land CO2 fluxes exhibited a significant diurnal variability and a substantial day-night difference. The net air-sea CO2 flux was -1.75 ± 0.98 μmol-C m-2 s-1, whereas the net air-land CO2 flux was 0.54 ± 7.35 μmol-C m-2 s-1, which indicated that in northwestern Taiwan, the coastal water acts as a sink of atmospheric CO2 but the coastal land acts as a source. The Random Forest Method was applied to hierarchize the influence of Chl-a, SST, DO, pH and U10 on air-sea CO2 fluxes. The result suggests that the strength of the diurnal air-sea CO2 flux is strongly influenced by the local wind speed.

  19. PHOTOMETRIC VARIABILITY OF THE DISK-INTEGRATED THERMAL EMISSION OF THE EARTH

    International Nuclear Information System (INIS)

    Gómez-Leal, I.; Selsis, F.; Pallé, E.

    2012-01-01

    Here we present an analysis of the global-integrated mid-infrared emission flux of the Earth based on data derived from satellite measurements. We have studied the photometric annual, seasonal, and rotational variability of the thermal emission of the Earth to determine which properties can be inferred from the point-like signal. We find that the analysis of the time series allows us to determine the 24 hr rotational period of the planet for most observing geometries, due to large warm and cold areas, identified with geographic features, which appear consecutively in the observer's planetary view. However, the effects of global-scale meteorology can effectively mask the rotation for several days at a time. We also find that orbital time series exhibit a seasonal modulation, whose amplitude depends strongly on the latitude of the observer but weakly on its ecliptic longitude. As no systematic difference of brightness temperature is found between the dayside and the nightside, the phase variations of the Earth in the infrared range are negligible. Finally, we also conclude that the phase variation of a spatially unresolved Earth-Moon system is dominated by the lunar signal.

  20. PHOTOMETRIC VARIABILITY IN KEPLER TARGET STARS: THE SUN AMONG STARS-A FIRST LOOK

    International Nuclear Information System (INIS)

    Basri, Gibor; Walkowicz, Lucianne M.; Batalha, Natalie; Jenkins, Jon; Borucki, William J.; Koch, David; Caldwell, Doug; Gilliland, Ronald L.; Dupree, Andrea K.; Latham, David W.; Meibom, Soeren; Howell, Steve; Brown, Tim

    2010-01-01

    The Kepler mission provides an exciting opportunity to study the light curves of stars with unprecedented precision and continuity of coverage. This is the first look at a large sample of stars with photometric data of a quality that has heretofore been only available for our Sun. It provides the first opportunity to compare the irradiance variations of our Sun to a large cohort of stars ranging from very similar to rather different stellar properties, at a wide variety of ages. Although Kepler data are in an early phase of maturity, and we only analyze the first month of coverage, it is sufficient to garner the first meaningful measurements of our Sun's variability in the context of a large cohort of main-sequence stars in the solar neighborhood. We find that nearly half of the full sample is more active than the active Sun, although most of them are not more than twice as active. The active fraction is closer to a third for the stars most similar to the Sun, and rises to well more than half for stars cooler than mid-K spectral types.

  1. Study of Diurnal Cycle Variability of Planetary Boundary Layer Characteristics over the Red Sea and Arabian Peninsula

    KAUST Repository

    Li, Weigang

    2012-07-01

    This work is aimed at investigating diurnal cycle variability of the planetary boundary layer characteristics over the Arabian Peninsula and the Red Sea region. To fulfill this goal the downscaling simulations are performed using Weather Research and Forecasting (WRF) model. We analyze planetary boundary layer height, latent and sensible heat fluxes, and surface air temperature. The model results are compared with observations in different areas, for different seasons, and for different model resolutions. The model results are analyzed in order to better quantify the diurnal cycle variability over the Arabian Peninsula and the Red Sea. The specific features of this region are investigated and discussed.

  2. Diurnal and seasonal variability of outdoor radon concentration in the area of the NRPI Prague.

    Science.gov (United States)

    Jilek, K; Slezákova, M; Thomas, J

    2014-07-01

    In autumn 2010, an outdoor measuring station for measurement of atmospheric radon, gamma equivalent dose rate in the range of 100 nSv h(-1)-1 Sv h(-1) and proper meteorological parameters such as thermal air gradient, relative air humidity, wind speed and direction and solar radiation intensity was built in the area of the National Radiation Protection Institute vvi. The station was designed to be independent of an electrical network and enables on-line wireless transfer of all data. After introduction of the station, illustrations of its measurement properties and the results of measured diurnal and seasonal variability of atmospheric radon, based on annual continuous measurement using a high-volume scintillation cell at a height of 2.5 m above the ground, are presented. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  3. ESA STSE Project “Sea Surface Temperature Diurnal Variability: Regional Extend – Implications in Atmospheric Modelling”

    DEFF Research Database (Denmark)

    Karagali, Ioanna

    of the vertical extend of diurnal signals. Drifting buoys provide measurements close to the surface but are not always available. Moored buoys are generally not able to resolve the daily SST signal, which strongly weakens with depth within the upper water column. For such reasons, the General Ocean Turbulence......, atmospheric and oceanic modelling, bio-chemical processes and oceanic CO2 studies. The diurnal variability of SST, driven by the coincident occurrence of low enough wind and solar heating, is currently not properly understood. Atmospheric, oceanic and climate models are currently not adequately resolving...... the daily SST variability, resulting in biases of the total heat budget estimates and therefore, demised model accuracies. The ESA STSE funded project SSTDV:R.EX.-IM.A.M. aimed at characterising the regional extend of diurnal SST signals and their impact in atmospheric modelling. This study will briefly...

  4. Diurnal, synoptic and seasonal variability of atmospheric CO2 in the Paris megacity area

    Science.gov (United States)

    Xueref-Remy, Irène; Dieudonné, Elsa; Vuillemin, Cyrille; Lopez, Morgan; Lac, Christine; Schmidt, Martina; Delmotte, Marc; Chevallier, Frédéric; Ravetta, François; Perrussel, Olivier; Ciais, Philippe; Bréon, François-Marie; Broquet, Grégoire; Ramonet, Michel; Spain, T. Gerard; Ampe, Christophe

    2018-03-01

    Most of the global fossil fuel CO2 emissions arise from urbanized and industrialized areas. Bottom-up inventories quantify them but with large uncertainties. In 2010-2011, the first atmospheric in situ CO2 measurement network for Paris, the capital of France, began operating with the aim of monitoring the regional atmospheric impact of the emissions coming from this megacity. Five stations sampled air along a northeast-southwest axis that corresponds to the direction of the dominant winds. Two stations are classified as rural (Traînou - TRN; Montgé-en-Goële - MON), two are peri-urban (Gonesse - GON; Gif-sur-Yvette - GIF) and one is urban (EIF, located on top of the Eiffel Tower). In this study, we analyze the diurnal, synoptic and seasonal variability of the in situ CO2 measurements over nearly 1 year (8 August 2010-13 July 2011). We compare these datasets with remote CO2 measurements made at Mace Head (MHD) on the Atlantic coast of Ireland and support our analysis with atmospheric boundary layer height (ABLH) observations made in the center of Paris and with both modeled and observed meteorological fields. The average hourly CO2 diurnal cycles observed at the regional stations are mostly driven by the CO2 biospheric cycle, the ABLH cycle and the proximity to urban CO2 emissions. Differences of several µmol mol-1 (ppm) can be observed from one regional site to the other. The more the site is surrounded by urban sources (mostly residential and commercial heating, and traffic), the more the CO2 concentration is elevated, as is the associated variability which reflects the variability of the urban sources. Furthermore, two sites with inlets high above ground level (EIF and TRN) show a phase shift of the CO2 diurnal cycle of a few hours compared to lower sites due to a strong coupling with the boundary layer diurnal cycle. As a consequence, the existence of a CO2 vertical gradient above Paris can be inferred, whose amplitude depends on the time of the day and on

  5. Diurnal, synoptic and seasonal variability of atmospheric CO2 in the Paris megacity area

    Directory of Open Access Journals (Sweden)

    I. Xueref-Remy

    2018-03-01

    Full Text Available Most of the global fossil fuel CO2 emissions arise from urbanized and industrialized areas. Bottom-up inventories quantify them but with large uncertainties. In 2010–2011, the first atmospheric in situ CO2 measurement network for Paris, the capital of France, began operating with the aim of monitoring the regional atmospheric impact of the emissions coming from this megacity. Five stations sampled air along a northeast–southwest axis that corresponds to the direction of the dominant winds. Two stations are classified as rural (Traînou – TRN; Montgé-en-Goële – MON, two are peri-urban (Gonesse – GON; Gif-sur-Yvette – GIF and one is urban (EIF, located on top of the Eiffel Tower. In this study, we analyze the diurnal, synoptic and seasonal variability of the in situ CO2 measurements over nearly 1 year (8 August 2010–13 July 2011. We compare these datasets with remote CO2 measurements made at Mace Head (MHD on the Atlantic coast of Ireland and support our analysis with atmospheric boundary layer height (ABLH observations made in the center of Paris and with both modeled and observed meteorological fields. The average hourly CO2 diurnal cycles observed at the regional stations are mostly driven by the CO2 biospheric cycle, the ABLH cycle and the proximity to urban CO2 emissions. Differences of several µmol mol−1 (ppm can be observed from one regional site to the other. The more the site is surrounded by urban sources (mostly residential and commercial heating, and traffic, the more the CO2 concentration is elevated, as is the associated variability which reflects the variability of the urban sources. Furthermore, two sites with inlets high above ground level (EIF and TRN show a phase shift of the CO2 diurnal cycle of a few hours compared to lower sites due to a strong coupling with the boundary layer diurnal cycle. As a consequence, the existence of a CO2 vertical gradient above Paris can be inferred, whose amplitude depends

  6. Photometrics Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — Purpose:The Photometrics Laboratory provides the capability to measure, analyze and characterize radiometric and photometric properties of light sources and filters,...

  7. The Tokar Gap Jet: Regional Circulation, Diurnal Variability, and Moisture Transport Based on Numerical Simulations

    KAUST Repository

    Davis, Shannon R.

    2015-05-14

    The structure, variability, and regional connectivity of the Tokar Gap jet (TGJ) are described using WRF Model analyses and supporting atmospheric datasets from the East African–Red Sea–Arabian Peninsula (EARSAP) region during summer 2008. Sources of the TGJ’s unique quasi-diurnal nature and association with atypically high atmospheric moisture transport are traced back to larger-scale atmospheric dynamics influencing its forcing. These include seasonal shifts in the intertropical convergence zone (ITCZ), variability of the monsoon and North African wind regimes, and ties to other orographic flow patterns. Strong modulation of the TGJ by regional processes such as the desert heating cycle, wind convergence at the ITCZ surface front, and the local land–sea breeze cycle are described. Two case studies present the interplay of these influences in detail. The first of these was an “extreme” gap wind event on 12 July, in which horizontal velocities in the Tokar Gap exceeded 26 m s−1 and the flow from the jet extended the full width of the Red Sea basin. This event coincided with development of a large mesoscale convective complex (MCC) and precipitation at the entrance of the Tokar Gap as well as smaller gaps downstream along the Arabian Peninsula. More typical behavior of the TGJ during the 2008 summer is discussed using a second case study on 19 July. Downwind impact of the TGJ is evaluated using Lagrangian model trajectories and analysis of the lateral moisture fluxes (LMFs) during jet events. These results suggest means by which TGJ contributes to large LMFs and has potential bearing upon Sahelian rainfall and MCC development.

  8. The global surface composition of 67P/Churyumov-Gerasimenko nucleus by Rosetta/VIRTIS. II) Diurnal and seasonal variability

    Science.gov (United States)

    Ciarniello, M.; Raponi, A.; Capaccioni, F.; Filacchione, G.; Tosi, F.; De Sanctis, M. C.; Kappel, D.; Rousseau, B.; Arnold, G.; Capria, M. T.; Barucci, M. A.; Quirico, E.; Longobardo, A.; Kuehrt, E.; Mottola, S.; Erard, S.; Bockelée-Morvan, D.; Leyrat, C.; Migliorini, A.; Zinzi, A.; Palomba, E.; Schmitt, B.; Piccioni, G.; Cerroni, P.; Ip, W.-H.; Rinaldi, G.; Salatti, M.

    2016-11-01

    VIRTIS-M observations of the nucleus of comet 67P/Churyumov-Gerasimenko acquired from 2014 August to 2015 May have been analysed to investigate surface temporal variability at both seasonal and diurnal scales. The measured reflectance spectra are studied by means of comet spectral indicators (CSI) such as slopes in the visible and infrared ranges, and 3.2 μm band area and band centre. CSI maps derived from data acquired at different heliocentric distances (from 3.62 to 1.72 au) along the inbound leg of the comet's orbit are used to infer surface water ice abundance. We measure a global scale enrichment of water ice from 2014 August to 2015 May across the body of the comet, along with variability at small spatial scale, possibly related with the local insolation conditions. Analysis of water ice diurnal variability is performed on 2014 August observations. Water ice appears at the border of receding shadows in the neck of the comet (Hapi), sublimating in less than 1 h, after exposure to sunlight. As similar variability is not observed in other regions of the comet, we interpreted this as the expression of a diurnal cycle of sublimation and re-condensation of water ice, triggered by sudden shadowing produced on the neck by the body and the head of the nucleus.

  9. An investigation of the photometric variability of confirmed and candidate Galactic Be stars using ASAS-3 data

    Science.gov (United States)

    Bernhard, Klaus; Otero, Sebastián; Hümmerich, Stefan; Kaltcheva, Nadejda; Paunzen, Ernst; Bohlsen, Terry

    2018-05-01

    We present an investigation of a large sample of confirmed (N=233) and candidate (N=54) Galactic classical Be stars (mean V magnitude range of 6.4 to 12.6 mag), with the main aim of characterizing their photometric variability. Our sample stars were preselected among early-type variables using light curve morphology criteria. Spectroscopic information was gleaned from the literature, and archival and newly-acquired spectra. Photometric variability was analyzed using archival ASAS-3 time series data. To enable a comparison of results, we have largely adopted the methodology of Labadie-Bartz et al. (2017), who carried out a similar investigation based on KELT data. Complex photometric variations were established in most stars: outbursts on different time-scales (in 73±5 % of stars), long-term variations (36±6 %), periodic variations on intermediate time-scales (1±1 %) and short-term periodic variations (6±3 %). 24±6 % of the outbursting stars exhibit (semi)periodic outbursts. We close the apparent void of rare outbursters reported by Labadie-Bartz et al. (2017), and show that Be stars with infrequent outbursts are not rare. While we do not find a significant difference in the percentage of stars showing outbursts among early-type, mid-type and late-type Be stars, we show that early-type Be stars exhibit much more frequent outbursts. We have measured rising and falling times for well-covered and well-defined outbursts. Nearly all outburst events are characterized by falling times that exceed the rising times. No differences were found between early-, mid- and late-type stars; a single non-linear function adequately describes the ratio of falling time to rising time across all spectral subtypes, with the ratio being larger for short events.

  10. Seasonal and diurnal variability of pressure fluctuation in the infrasound frequency range observed in the Czech microbarograph network

    Czech Academy of Sciences Publication Activity Database

    Šindelářová, Tereza; Kozubek, Michal; Chum, Jaroslav; Potužníková, Kateřina

    2016-01-01

    Roč. 60, č. 2 (2016), s. 747-762 ISSN 0039-3169 R&D Projects: GA ČR GP13-09778P; GA ČR(CZ) GAP209/12/2440 Institutional support: RVO:68378289 Keywords : infrasound environments * Czech microbarograph network * seasonal and diurnal variability Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 0.764, year: 2016 http://link.springer.com/article/10.1007/s11200-015-0250-1

  11. Variability of Diurnal Temperature Range During Winter Over Western Himalaya: Range- and Altitude-Wise Study

    Science.gov (United States)

    Shekhar, M. S.; Devi, Usha; Dash, S. K.; Singh, G. P.; Singh, Amreek

    2018-04-01

    The current trends in diurnal temperature range, maximum temperature, minimum temperature, mean temperature, and sun shine hours over different ranges and altitudes of Western Himalaya during winter have been studied. Analysis of 25 years of data shows an increasing trend in diurnal temperature range over all the ranges and altitudes of Western Himalaya during winter, thereby confirming regional warming of the region due to present climate change and global warming. Statistical studies show significant increasing trend in maximum temperature over all the ranges and altitudes of Western Himalaya. Minimum temperature shows significant decreasing trend over Pir Panjal and Shamshawari range and significant increasing trend over higher altitude of Western Himalaya. Similarly, sunshine hours show significant decreasing trend over Karakoram range. There exists strong positive correlation between diurnal temperature range and maximum temperature for all the ranges and altitudes of Western Himalaya. Strong negative correlation exists between diurnal temperature range and minimum temperature over Shamshawari and Great Himalaya range and lower altitude of Western Himalaya. Sunshine hours show strong positive correlation with diurnal temperature range over Pir Panjal and Great Himalaya range and lower and higher altitudes.

  12. Meteorological controls on the diurnal variability of carbon monoxide mixing ratio at a mountaintop monitoring site in the Appalachian Mountains

    Directory of Open Access Journals (Sweden)

    Temple R. Lee

    2015-05-01

    Full Text Available The variability of trace gases such as carbon monoxide (CO at surface monitoring stations is affected by meteorological forcings that are particularly complicated over mountainous terrain. A detailed understanding of the impact of meteorological forcings on trace gas variability is challenging, but is vital to distinguish trace gas measurements affected by local pollutant sources from measurements representative of background mixing ratios. In the present study, we investigate the meteorological and CO characteristics at Pinnacles (38.61 N, 78.35 W, 1017 m above mean sea level, a mountaintop monitoring site in northwestern Virginia, USA, in the Appalachian Mountains, from 2009 to 2012, and focus on understanding the dominant meteorological forcings affecting the CO variability on diurnal timescales. The annual mean diurnal CO cycle shows a minimum in the morning between 0700 and 0900 LST and a maximum in the late afternoon between 1600 and 2000 LST, with a mean (median daily CO amplitude of 39.2±23.7 ppb (33.2 ppb. CO amplitudes show large day-to-day variability. The largest CO amplitudes, in which CO mixing ratios can change >100 ppb in <3 h, occur in the presence of synoptic disturbances. Under fair weather conditions, local- to regional-scale transport processes are found to be more important drivers of the diurnal CO variability. On fair weather days with northwesterly winds, boundary layer dilution causes a daytime CO decrease, resembling the variability observed atop tall towers in flat terrain. Fair weather days with a wind shift from the northwest to the south are characterised by an afternoon CO increase and resemble the variability observed at mountaintops influenced by the vertical transport of polluted air from adjacent valleys.

  13. Photometric variability in a warm, strongly magnetic DQ white dwarf, SDSS J103655.39+652252.2

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Kurtis A. [Department of Physics and Astronomy, Texas A and M University-Commerce, P.O. Box 3011, Commerce, TX 75429 (United States); Winget, D. E.; Montgomery, M. H.; Hermes, J. J.; Falcon, Ross E.; Winget, K. I. [Department of Astronomy, University of Texas, 1 University Station C1400, Austin, TX 78712 (United States); Dufour, Patrick [Département de Physique, Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, QC H3C 3J7 (Canada); Kepler, S. O. [Departamento de Astronomia, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500 Porto Alegre 91501-970, RS (Brazil); Bolte, Michael [UCO/Lick Observatory, University of California, 1156 High St., Santa Cruz, CA 95064 (United States); Rubin, Kate H. R. [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Liebert, James, E-mail: Kurtis.Williams@tamuc.edu, E-mail: jamesliebert@gmail.com [Emeritus, Steward Observatory, University of Arizona, 933 N. Cherry Ave., Tucson, AZ 85721 (United States)

    2013-06-01

    We present the discovery of photometric variability in the DQ white dwarf SDSS J103655.39+652252.2 (SDSS J1036+6522). Time-series photometry reveals a coherent monoperiodic modulation at a period of 1115.64751(67) s with an amplitude 0.442% ± 0.024%; no other periodic modulations are observed with amplitudes ≳ 0.13%. The period, amplitude, and phase of this modulation are constant within errors over 16 months. The spectrum of SDSS J1036+6522 shows magnetic splitting of carbon lines, and we use Paschen-Back formalism to develop a grid of model atmospheres for mixed carbon and helium atmospheres. Our models, while reliant on several simplistic assumptions, nevertheless match the major spectral and photometric properties of the star with a self-consistent set of parameters: T {sub eff} ≈ 15, 500 K, log g ≈ 9, log (C/He) = –1.0, and a mean magnetic field strength of 3.0 ± 0.2 MG. The temperature and abundances strongly suggest that SDSS J1036+6522 is a transition object between the hot, carbon-dominated DQs and the cool, helium-dominated DQs. The variability of SDSS J1036+6522 has characteristics similar to those of the variable hot carbon-atmosphere white dwarfs (DQVs), however, its temperature is significantly cooler. The pulse profile of SDSS J1036+6522 is nearly sinusoidal, in contrast with the significantly asymmetric pulse shapes of the known magnetic DQVs. If the variability in SDSS J1036+6522 is due to the same mechanism as other DQVs, then the pulse shape is not a definitive diagnostic on the absence of a strong magnetic field in DQVs. It remains unclear whether the root cause of the variability in SDSS J1036+6522 and the other hot DQVs is the same.

  14. Photometric variability in a warm, strongly magnetic DQ white dwarf, SDSS J103655.39+652252.2

    International Nuclear Information System (INIS)

    Williams, Kurtis A.; Winget, D. E.; Montgomery, M. H.; Hermes, J. J.; Falcon, Ross E.; Winget, K. I.; Dufour, Patrick; Kepler, S. O.; Bolte, Michael; Rubin, Kate H. R.; Liebert, James

    2013-01-01

    We present the discovery of photometric variability in the DQ white dwarf SDSS J103655.39+652252.2 (SDSS J1036+6522). Time-series photometry reveals a coherent monoperiodic modulation at a period of 1115.64751(67) s with an amplitude 0.442% ± 0.024%; no other periodic modulations are observed with amplitudes ≳ 0.13%. The period, amplitude, and phase of this modulation are constant within errors over 16 months. The spectrum of SDSS J1036+6522 shows magnetic splitting of carbon lines, and we use Paschen-Back formalism to develop a grid of model atmospheres for mixed carbon and helium atmospheres. Our models, while reliant on several simplistic assumptions, nevertheless match the major spectral and photometric properties of the star with a self-consistent set of parameters: T eff ≈ 15, 500 K, log g ≈ 9, log (C/He) = –1.0, and a mean magnetic field strength of 3.0 ± 0.2 MG. The temperature and abundances strongly suggest that SDSS J1036+6522 is a transition object between the hot, carbon-dominated DQs and the cool, helium-dominated DQs. The variability of SDSS J1036+6522 has characteristics similar to those of the variable hot carbon-atmosphere white dwarfs (DQVs), however, its temperature is significantly cooler. The pulse profile of SDSS J1036+6522 is nearly sinusoidal, in contrast with the significantly asymmetric pulse shapes of the known magnetic DQVs. If the variability in SDSS J1036+6522 is due to the same mechanism as other DQVs, then the pulse shape is not a definitive diagnostic on the absence of a strong magnetic field in DQVs. It remains unclear whether the root cause of the variability in SDSS J1036+6522 and the other hot DQVs is the same.

  15. Amazon forest structure generates diurnal and seasonal variability in light utilization

    Science.gov (United States)

    Douglas C. Morton; Jeremy Rubio; Bruce D. Cook; Jean-Philippe Gastellu-Etchegorry; Marcos Longo; Hyeungu Choi; Maria Hunter; Michael Keller

    2016-01-01

    The complex three-dimensional (3-D) structure of tropical forests generates a diversity of light environments for canopy and understory trees. Understanding diurnal and seasonal changes in light availability is critical for interpreting measurements of net ecosystem exchange and improving ecosystem models. Here, we used the Discrete Anisotropic Radiative Transfer (DART...

  16. The Solar Neighborhood. XLI. A Study of the Wide Main Sequence for M Dwarfs—Long-term Photometric Variability

    Energy Technology Data Exchange (ETDEWEB)

    Clements, Tiffany D.; Jao, Wei-Chun; Silverstein, Michele L. [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States); Henry, Todd J.; Hosey, Altonio D. [RECONS Institute, Chambersburg, PA 17201 (United States); Winters, Jennifer G. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Dieterich, Sergio B. [Carnegie Institution for Science, Washington, DC 20015 (United States); Riedel, Adric R., E-mail: pewett@astro.gsu.edu, E-mail: jao@astro.gsu.edu, E-mail: silverstein@astro.gsu.edu, E-mail: toddhenry28@gmail.com, E-mail: altoniohosey@gmail.com, E-mail: jennifer.winters@cfa.harvard.edu, E-mail: sdieterich@carnegiescience.edu, E-mail: adric.riedel@gmail.com [Space Telescope Science Institute, Baltimore, MD 21218 (United States)

    2017-09-01

    We report findings from a long-term photometric variability study of M dwarfs carried out at the SMARTS 0.9 m telescope at the Cerro Tololo Inter-American Observatory. As part of a multi-faceted effort to investigate the range of luminosities of M dwarfs of a given color on the Hertzsprung–Russell Diagram, 76 M dwarfs have been observed for 3–17 years in the Johnson–Kron–Cousins V band. We find that stars elevated above the center of the main sequence distribution tend to have higher levels of variability, likely caused by magnetic activity, than their fainter counterparts below the center. This study provides insight into how the long-term magnetic activity of these stars may be affecting their sizes, luminosities, and thus positions on the H-R Diagram.

  17. The effects of the diurnal atmospheric variability on entry, descent and landing on Mars

    Directory of Open Access Journals (Sweden)

    Marčeta D.

    2014-01-01

    Full Text Available Landing on Mars is extremely challenging task due to the fact that the Martian atmosphere is the most hostile environment in the Solar system to perform the entry, descent and landing (EDL process, because it is thick enough to create substantial heating of the entry vehicle but not thick enough to reduce its velocity to the one necessary for safe landing. Beside this, the atmosphere is very dynamic mainly due to high eccentricity of the Martian orbit, obliquity of the orbital to the equatorial plane and close alignment of the winter solstice and the orbital perihelion. Although seasonal variations of atmospheric parameters are significantly larger than the diurnal, it is very important to analyze diurnal cycles as they can significantly change vertical and horizontal atmospheric profiles in very short time intervals. This can present a serious threat to missions which have very precise timings and specific requirements such as the requirement for the daytime landing to enable ground images acquisition during the descent and landing phase. A 3-degrees-of-freedom trajectory integration routine was combined with the Mars Global Reference Atmospheric Model (Mars-GRAM to identify the dependence of the EDL profiles on the diurnal cycles of atmospheric parameters throughout the Martian year. The obtained results show that the influence of the diurnal cycles is the largest at the equator and decreases relatively symmetrically towards the poles with a slightly stronger influence in the northern hemisphere. Also, there is a significant influence of the orbital position of Mars on the effect of diurnal atmospheric variations which causes that, around the orbital perihelion and winter solstice, there is some kind of inversion of the dependance of optimal entry timing on latitude of the landing site comparing to the rest of the Martian year. [Projekat Ministarstva nauke Republike Srbije, br. 176002

  18. Weather on Other Worlds. IV. Hα Emission and Photometric Variability Are Not Correlated in L0–T8 Dwarfs

    Energy Technology Data Exchange (ETDEWEB)

    Miles-Páez, Paulo A.; Metchev, Stanimir A. [Department of Physics and Astronomy and Centre for Planetary Science and Exploration, The University of Western Ontario, London, Ontario N6A 3K7 (Canada); Heinze, Aren [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Apai, Dániel, E-mail: ppaez@uwo.ca [The University of Arizona, Department of Astronomy, 933 North Cherry Avenue, Tucson, AZ 85721 (United States)

    2017-05-10

    Recent photometric studies have revealed that surface spots that produce flux variations are present on virtually all L and T dwarfs. Their likely magnetic or dusty nature has been a much-debated problem, the resolution to which has been hindered by paucity of diagnostic multi-wavelength observations. To test for a correlation between magnetic activity and photometric variability, we searched for H α emission among eight L3–T2 ultra-cool dwarfs with extensive previous photometric monitoring, some of which are known to be variable at 3.6 μ m or 4.5 μ m. We detected H α only in the non-variable T2 dwarf 2MASS J12545393−0122474. The remaining seven objects do not show H α emission, even though six of them are known to vary photometrically. Combining our results with those for 86 other L and T dwarfs from the literature show that the detection rate of H α emission is very high (94%) for spectral types between L0 and L3.5 and much smaller (20%) for spectral types ≥L4, while the detection rate of photometric variability is approximately constant (30%–55%) from L0 to T8 dwarfs. We conclude that chromospheric activity, as evidenced by H α emission, and large-amplitude photometric variability are not correlated. Consequently, dust clouds are the dominant driver of the observed variability of ultra-cool dwarfs at spectral types, at least as early as L0.

  19. Weather on Other Worlds. IV. Hα Emission and Photometric Variability Are Not Correlated in L0–T8 Dwarfs

    International Nuclear Information System (INIS)

    Miles-Páez, Paulo A.; Metchev, Stanimir A.; Heinze, Aren; Apai, Dániel

    2017-01-01

    Recent photometric studies have revealed that surface spots that produce flux variations are present on virtually all L and T dwarfs. Their likely magnetic or dusty nature has been a much-debated problem, the resolution to which has been hindered by paucity of diagnostic multi-wavelength observations. To test for a correlation between magnetic activity and photometric variability, we searched for H α emission among eight L3–T2 ultra-cool dwarfs with extensive previous photometric monitoring, some of which are known to be variable at 3.6 μ m or 4.5 μ m. We detected H α only in the non-variable T2 dwarf 2MASS J12545393−0122474. The remaining seven objects do not show H α emission, even though six of them are known to vary photometrically. Combining our results with those for 86 other L and T dwarfs from the literature show that the detection rate of H α emission is very high (94%) for spectral types between L0 and L3.5 and much smaller (20%) for spectral types ≥L4, while the detection rate of photometric variability is approximately constant (30%–55%) from L0 to T8 dwarfs. We conclude that chromospheric activity, as evidenced by H α emission, and large-amplitude photometric variability are not correlated. Consequently, dust clouds are the dominant driver of the observed variability of ultra-cool dwarfs at spectral types, at least as early as L0.

  20. Variability of radiatively forced diurnal cycle of intense convection in the tropical west pacific

    Energy Technology Data Exchange (ETDEWEB)

    Gray, W.M.; Sheaffer, J.D.; Thorson, W.B. [Colorado State Univ., Fort Collins, CO (United States)

    1996-04-01

    Strong differences occur in daytime versus nighttime (DVN) net radiative cooling in clear versus cloudy areas of the tropical atmosphere. Daytime average cooling is approximately -0.7{degrees}C/day, whereas nighttime net tropospheric cooling rates are about -1.5{degrees}C/day, an approximately two-to-one difference. The comparatively strong nocturnal cooling in clear areas gives rise to a diurnally varying vertical circulation and horizontal convergence cycle. Various manifestations of this cyclic process include the observed early morning heavy rainfall maxima over the tropical oceans. The radiatively driven DVN circulation appears to strongly modulate the resulting diurnal cycle of intense convection which creates the highest, coldest cloudiness over maritime tropical areas and is likely a fundamental mechanism governing both small and large scale dynamics over much of the tropical environment.

  1. Analysis on diurnal global geomagnetic variability under quiet-time conditions

    OpenAIRE

    Klausner, Virginia; Domingues, Margarete Oliveira; Mendes Jr, Odim; Papa, Andres Reinaldo Rodriguez; Frick, Peter

    2012-01-01

    This paper describes a methodology (or treatment) to establish a representative signal of the global magnetic diurnal variation based on a spatial distribution in both longitude and latitude of a set of magnetic stations as well as their magnetic behavior on a time basis. For that, we apply the Principal Component Analysis (PCA) technique implemented using gapped wavelet transform and wavelet correlation. The continuous gapped wavelet and the wavelet correlation techniques were used to descri...

  2. Tidal influences on vertical diffusion and diurnal variability of ozone in the mesosphere

    Science.gov (United States)

    Bjarnason, Gudmundur G.; Solomon, Susan; Garcia, Rolando R.

    1987-01-01

    Possible dynamical influences on the diurnal behavior of ozone are investigated. A time dependent one-dimensional photochemical model is developed for this purpose; all model calculations are made at 70 deg N during summer. It is shown that the vertical diffusion can vary as much as 1 order of magnitude within a day as a result of large changes in the zonal wind induced by atmospheric thermal tides. It is found that by introducing a dissipation time scale for turbulence produced by breaking gravity waves, the agreement with Poker Flat echo data is improved. Comparisons of results from photochemical model calculations, where the vertical diffusion is a function of height only, with those in which the vertical diffusion coefficient is changing in time show large differences in the diurnal behavior of ozone between 70 and 90 km. By including the dynamical effect, much better agreement with the Solar Mesosphere Explorers data is obtained. The results are, however, sensitive to the background zonally averaged wind. The influence of including time-varying vertical diffusion coefficient on the OH densities is also large, especially between 80 and 90 km. This suggests that dynamical effects are important in determining the diurnal behavior of the airglow emission from the Meinel bands.

  3. PRECISION PHOTOMETRIC MONITORING OF VERY LOW MASS σ ORIONIS CLUSTER MEMBERS: VARIABILITY AND ROTATION AT A FEW Myr

    International Nuclear Information System (INIS)

    Cody, Ann Marie; Hillenbrand, Lynne A.

    2010-01-01

    We present high-precision photometry on 107 variable low-mass stars and brown dwarfs in the ∼3 Myr σ Orionis open cluster. We have carried out I-band photometric monitoring within two fields, encompassing 153 confirmed or candidate members of the low-mass cluster population, from 0.02 to 0.5 M sun . We are sensitive to brightness changes on timescales from 10 minutes to two weeks with amplitudes as low as 0.004 mag, and find variability on these timescales in nearly 70% of cluster members. We identify both periodic and aperiodic modes of variability, as well as semi-periodic rapid fading events that are not accounted for by the standard explanations of rotational modulation of surface features or accretion. We have incorporated both optical and infrared color data to uncover trends in variability with mass and circumstellar disks. While the data confirm that the lowest-mass objects (M sun ) rotate more rapidly than the 0.2-0.5 M sun members, they do not support a direct connection between rotation rate and the presence of a disk. Finally, we speculate on the origin of irregular variability in cluster members with no evidence for disks or accretion.

  4. Diurnal and vertical variability of the sensible heat and carbon dioxide budgets in the atmospheric surface layer

    International Nuclear Information System (INIS)

    Casso-Torralba, P.; Rosa Soler, M.; Vila-Guerau de Arellano, J.; Bosveld, F.; Vermeulen, A.; Werner, C.; Moors, E.

    2008-08-01

    The diurnal and vertical variability of heat and carbon dioxide (CO2) in the atmospheric surface layer are studied by analyzing measurements from a 213 m tower in Cabauw (Netherlands). Observations of thermodynamic variables and CO2 mixing ratio as well as vertical profiles of the turbulent fluxes are used to retrieve the contribution of the budget terms in the scalar conservation equation. On the basis of the daytime evolution of turbulent fluxes, we calculate the budget terms by assuming that turbulent fluxes follow a linear profile with height. This assumption is carefully tested and the deviation from linearity is quantified. The budget calculation allows us to assess the importance of advection of heat and CO2 during day hours for three selected days. It is found that, under nonadvective conditions, the diurnal variability of temperature and CO2 is well reproduced from the flux divergence measurements. Consequently, the vertical transport due to the turbulent flux plays a major role in the daytime evolution of both scalars and the advection is a relatively small contribution. During the analyzed days with a strong contribution of advection of either heat or carbon dioxide, the flux divergence is still an important contribution to the budget. For heat, the quantification of the advection contribution is in close agreement with results from a numerical model. For carbon dioxide, we qualitatively corroborate the results with a Lagrangian transport model. Our estimation of advection is compared with traditional estimations based on the Net Ecosystem-atmosphere Exchange (NEE)

  5. IMPROVED VARIABLE STAR SEARCH IN LARGE PHOTOMETRIC DATA SETS: NEW VARIABLES IN CoRoT FIELD LRa02 DETECTED BY BEST II

    International Nuclear Information System (INIS)

    Fruth, T.; Cabrera, J.; Csizmadia, Sz.; Eigmüller, P.; Erikson, A.; Kirste, S.; Pasternacki, T.; Rauer, H.; Titz-Weider, R.; Kabath, P.; Chini, R.; Lemke, R.; Murphy, M.

    2012-01-01

    The CoRoT field LRa02 has been observed with the Berlin Exoplanet Search Telescope II (BEST II) during the southern summer 2007/2008. A first analysis of stellar variability led to the publication of 345 newly discovered variable stars. Now, a deeper analysis of this data set was used to optimize the variability search procedure. Several methods and parameters have been tested in order to improve the selection process compared to the widely used J index for variability ranking. This paper describes an empirical approach to treat systematic trends in photometric data based upon the analysis of variance statistics that can significantly decrease the rate of false detections. Finally, the process of reanalysis and method improvement has virtually doubled the number of variable stars compared to the first analysis by Kabath et al. A supplementary catalog of 272 previously unknown periodic variables plus 52 stars with suspected variability is presented. Improved ephemerides are given for 19 known variables in the field. In addition, the BEST II results are compared with CoRoT data and its automatic variability classification.

  6. A photometric study of the giant red variable stars with small amplitudes

    International Nuclear Information System (INIS)

    Wisse, P.N.J.

    1979-01-01

    Three colour UBV observations of southern semiregular and irregular red variable stars are presented. Well covered light and colour curves have been obtained for ca. 40 stars. In most cases the observations span more than one cycle. A short description is given for all individual variables. The observations are accurate enough to reveal many minor irregularities in the light variation. The SRb and Lb variables define a narrow curved strip in the (U-B) - (B-V) diagram. This strip has been called the Locus of Red Variables (LRV). The (U-B) of the variables is about 0.5 magnitudes bluer than that of the K III giants. (Auth.)

  7. The Seasonal and Intraseasonal Variability of Diurnal Cloud Activity over the Tibetan Plateau

    OpenAIRE

    Hatsuki, Fujinami; Tetsuzo, Yasunari; Institute of Geoscience, University of Tsukuba; Institute of Geoscience, University of Tsukuba

    2001-01-01

    Seasonal variation of diurnal cloud activity(abbreviated DCA)over the Tibetan Plateau throughout the year is examined using 3-hourly geostationary meteorological satellite(GMS)data for 6-years(1989-1994). The DCA shows two distinct variance maxima in the seasonal cycle. One is in spring(pre-monsoon season), and the other is in the summer monsoon season. The DCA begins in late January, and reaches its maximum from March through April. The active DCA extends over almost the whole of the plateau...

  8. Diurnal global variability of the Earth's magnetic field during geomagnetically quiet conditions

    Science.gov (United States)

    Klausner, V.

    2012-12-01

    This work proposes a methodology (or treatment) to establish a representative signal of the global magnetic diurnal variation. It is based on a spatial distribution in both longitude and latitude of a set of magnetic stations as well as their magnetic behavior on a time basis. We apply the Principal Component Analysis (PCA) technique using gapped wavelet transform and wavelet correlation. This new approach was used to describe the characteristics of the magnetic variations at Vassouras (Brazil) and 12 other magnetic stations spread around the terrestrial globe. Using magnetograms from 2007, we have investigated the global dominant pattern of the Sq variation as a function of low solar activity. This year was divided into two seasons for seasonal variation analysis: solstices (June and December) and equinoxes (March and September). We aim to reconstruct the original geomagnetic data series of the H component taking into account only the diurnal variations with periods of 24 hours on geomagnetically quiet days. We advance a proposal to reconstruct the Sq baseline using only the PCA first mode. The first interpretation of the results suggests that PCA/wavelet method could be used to the reconstruction of the Sq baseline.

  9. THE FIRST DETECTION OF PHOTOMETRIC VARIABILITY IN A Y DWARF: WISE J140518.39+553421.3

    International Nuclear Information System (INIS)

    Cushing, Michael C.; Hardegree-Ullman, Kevin K.; Trucks, Jesica L.; Morley, Caroline V.; Fortney, Jonathan J.; Gizis, John E.; Marley, Mark S.; Gelino, Christopher R.; Kirkpatrick, J. Davy; Mace, Gregory N.; Carey, Sean J.

    2016-01-01

    We present the first detection of the photometric variability in a spectroscopically confirmed Y dwarf. The Infrared Array Camera on board the Spitzer Space Telescope was used to obtain time series photometry of WISE J140518.39+553421.3 at 3.6 and 4.5 μ m over a 24-hr period at two different epochs separated by 149 days. Variability is evident at 4.5 μ m in the first epoch and at 3.6 and 4.5 μ m in the second epoch, which suggests that the underlying cause or causes of this variability change on the timescales of months. The second-epoch [3.6] and [4.5] light curves are nearly sinusoidal in form, in phase, have periods of roughly 8.5 hr, and have semi-amplitudes of 3.5%. We find that a simple geometric spot model with a single bright spot reproduces these observations well. We also compare our measured semi-amplitudes of the second-epoch light curves to predictions of the static, one-dimensional, partly cloudy, and hot spot models of Morley and collaborators, and find that neither set of models can reproduce the observed [3.6] and [4.5] semi-amplitudes simultaneously. Therefore, more advanced two-dimensional or three-dimensional models that include time-dependent phenomena like vertical mixing, cloud formation, and thermal relaxation are sorely needed in order to properly interpret our observations.

  10. Variable stars classification based on photometric data from the "Pi of the Sky" project

    Science.gov (United States)

    Majczyna, A.; Nalezyty, M.; Siudek, M.; Malek, K.; Barnacka, A.; Mankiewicz, L.; Żarnecki, A. F.

    2009-06-01

    We present the first few steps of creation the second edition of the variable stars catalogue, based on the "Pi of the Sky" data, collected during two years 2006-2007. We have chosen - 3000 variable star candidates from about 1.5 million objects.

  11. Photometric and spectroscopic variability of the B5IIIe star HD 171219

    Science.gov (United States)

    Andrade, L.; Janot-Pacheco, E.; Emilio, M.; Frémat, Y.; Neiner, C.; Poretti, E.; Mathias, P.; Rainer, M.; Suárez, J. C.; Uytterhoeven, K.; Briquet, M.; Diago, P. D.; Fabregat, J.; Gutiérrez-Soto, J.

    2017-07-01

    We analyzed the star HD 171219, one of the relatively bright Be stars observed in the seismo field of the CoRoT satellite, in order to determine its physical and pulsation characteristics. Classical Be stars are main-sequence objects of mainly B-type, whose spectra show, or have shown at some epoch, Balmer lines in emission and an infrared excess. Both characteristics are attributed to an equatorially concentrated circumstellar disk fed by non-periodic mass-loss episodes (outbursts). Be stars often show nonradial pulsation gravity modes and, as more recently discovered, stochastically excited oscillations. Applying the CLEANEST algorithm to the high-cadence and highly photometrically precise measurements of the HD 171219 light curve led us to perform an unprecedented detailed analysis of its nonradial pulsations. Tens of frequencies have been detected in the object compatible with nonradial g-modes. Additional high-resolution ground-based spectroscopic observations were obtained at La Silla (HARPS) and Haute Provence (SOPHIE) observatories during the month preceding CoRoT observations. Additional information was obtained from low-resolution spectra from the BeSS database. From spectral line fitting we determined physical parameters of the star, which is seen equator-on (I = 90°). We also found in the ground data the same frequencies as in CoRoT data. Additionally, we analyzed the circumstellar activity through the traditional method of violet to red emission Hα line variation. A quintuplet was identified at approximately 1.113 c d-1 (12.88 μHz) with a separation of 0.017 c d-1 that can be attributed to a pulsation degree ℓ 2. The light curve shows six small- to medium-scale outbursts during the CoRoT observations. The intensity of the main frequencies varies after each outburst, suggesting a possible correlation between the nonradial pulsations regime and the feeding of the envelope. The CoRoT space mission was developed and operated by the French space agency

  12. Photometric search for variable stars in the young open cluster Berkeley 59

    Science.gov (United States)

    Lata, Sneh; Pandey, A. K.; Maheswar, G.; Mondal, Soumen; Kumar, Brijesh

    2011-12-01

    We present the time series photometry of stars located in the extremely young open cluster Berkeley 59. Using the 1.04-m telescope at Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital, we have identified 42 variables in a field of ˜13 × 13 arcmin2 around the cluster. The probable members of the cluster have been identified using a (V, V-I) colour-magnitude diagram and a (J-H, H-K) colour-colour diagram. 31 variables have been found to be pre-main-sequence stars associated with the cluster. The ages and masses of the pre-main-sequence stars have been derived from the colour-magnitude diagram by fitting theoretical models to the observed data points. The ages of the majority of the probable pre-main-sequence variable candidates range from 1 to 5 Myr. The masses of these pre-main-sequence variable stars have been found to be in the range of ˜0.3 to ˜3.5 M⊙, and these could be T Tauri stars. The present statistics reveal that about 90 per cent T Tauri stars have period dispersal of the discs of relatively massive stars.

  13. ACTIVE LEARNING TO OVERCOME SAMPLE SELECTION BIAS: APPLICATION TO PHOTOMETRIC VARIABLE STAR CLASSIFICATION

    Energy Technology Data Exchange (ETDEWEB)

    Richards, Joseph W.; Starr, Dan L.; Miller, Adam A.; Bloom, Joshua S.; Butler, Nathaniel R.; Berian James, J. [Astronomy Department, University of California, Berkeley, CA 94720-7450 (United States); Brink, Henrik [Dark Cosmology Centre, Juliane Maries Vej 30, 2100 Copenhagen O (Denmark); Long, James P.; Rice, John, E-mail: jwrichar@stat.berkeley.edu [Statistics Department, University of California, Berkeley, CA 94720-7450 (United States)

    2012-01-10

    Despite the great promise of machine-learning algorithms to classify and predict astrophysical parameters for the vast numbers of astrophysical sources and transients observed in large-scale surveys, the peculiarities of the training data often manifest as strongly biased predictions on the data of interest. Typically, training sets are derived from historical surveys of brighter, more nearby objects than those from more extensive, deeper surveys (testing data). This sample selection bias can cause catastrophic errors in predictions on the testing data because (1) standard assumptions for machine-learned model selection procedures break down and (2) dense regions of testing space might be completely devoid of training data. We explore possible remedies to sample selection bias, including importance weighting, co-training, and active learning (AL). We argue that AL-where the data whose inclusion in the training set would most improve predictions on the testing set are queried for manual follow-up-is an effective approach and is appropriate for many astronomical applications. For a variable star classification problem on a well-studied set of stars from Hipparcos and Optical Gravitational Lensing Experiment, AL is the optimal method in terms of error rate on the testing data, beating the off-the-shelf classifier by 3.4% and the other proposed methods by at least 3.0%. To aid with manual labeling of variable stars, we developed a Web interface which allows for easy light curve visualization and querying of external databases. Finally, we apply AL to classify variable stars in the All Sky Automated Survey, finding dramatic improvement in our agreement with the ASAS Catalog of Variable Stars, from 65.5% to 79.5%, and a significant increase in the classifier's average confidence for the testing set, from 14.6% to 42.9%, after a few AL iterations.

  14. ACTIVE LEARNING TO OVERCOME SAMPLE SELECTION BIAS: APPLICATION TO PHOTOMETRIC VARIABLE STAR CLASSIFICATION

    International Nuclear Information System (INIS)

    Richards, Joseph W.; Starr, Dan L.; Miller, Adam A.; Bloom, Joshua S.; Butler, Nathaniel R.; Berian James, J.; Brink, Henrik; Long, James P.; Rice, John

    2012-01-01

    Despite the great promise of machine-learning algorithms to classify and predict astrophysical parameters for the vast numbers of astrophysical sources and transients observed in large-scale surveys, the peculiarities of the training data often manifest as strongly biased predictions on the data of interest. Typically, training sets are derived from historical surveys of brighter, more nearby objects than those from more extensive, deeper surveys (testing data). This sample selection bias can cause catastrophic errors in predictions on the testing data because (1) standard assumptions for machine-learned model selection procedures break down and (2) dense regions of testing space might be completely devoid of training data. We explore possible remedies to sample selection bias, including importance weighting, co-training, and active learning (AL). We argue that AL—where the data whose inclusion in the training set would most improve predictions on the testing set are queried for manual follow-up—is an effective approach and is appropriate for many astronomical applications. For a variable star classification problem on a well-studied set of stars from Hipparcos and Optical Gravitational Lensing Experiment, AL is the optimal method in terms of error rate on the testing data, beating the off-the-shelf classifier by 3.4% and the other proposed methods by at least 3.0%. To aid with manual labeling of variable stars, we developed a Web interface which allows for easy light curve visualization and querying of external databases. Finally, we apply AL to classify variable stars in the All Sky Automated Survey, finding dramatic improvement in our agreement with the ASAS Catalog of Variable Stars, from 65.5% to 79.5%, and a significant increase in the classifier's average confidence for the testing set, from 14.6% to 42.9%, after a few AL iterations.

  15. Active Learning to Overcome Sample Selection Bias: Application to Photometric Variable Star Classification

    Science.gov (United States)

    Richards, Joseph W.; Starr, Dan L.; Brink, Henrik; Miller, Adam A.; Bloom, Joshua S.; Butler, Nathaniel R.; James, J. Berian; Long, James P.; Rice, John

    2012-01-01

    Despite the great promise of machine-learning algorithms to classify and predict astrophysical parameters for the vast numbers of astrophysical sources and transients observed in large-scale surveys, the peculiarities of the training data often manifest as strongly biased predictions on the data of interest. Typically, training sets are derived from historical surveys of brighter, more nearby objects than those from more extensive, deeper surveys (testing data). This sample selection bias can cause catastrophic errors in predictions on the testing data because (1) standard assumptions for machine-learned model selection procedures break down and (2) dense regions of testing space might be completely devoid of training data. We explore possible remedies to sample selection bias, including importance weighting, co-training, and active learning (AL). We argue that AL—where the data whose inclusion in the training set would most improve predictions on the testing set are queried for manual follow-up—is an effective approach and is appropriate for many astronomical applications. For a variable star classification problem on a well-studied set of stars from Hipparcos and Optical Gravitational Lensing Experiment, AL is the optimal method in terms of error rate on the testing data, beating the off-the-shelf classifier by 3.4% and the other proposed methods by at least 3.0%. To aid with manual labeling of variable stars, we developed a Web interface which allows for easy light curve visualization and querying of external databases. Finally, we apply AL to classify variable stars in the All Sky Automated Survey, finding dramatic improvement in our agreement with the ASAS Catalog of Variable Stars, from 65.5% to 79.5%, and a significant increase in the classifier's average confidence for the testing set, from 14.6% to 42.9%, after a few AL iterations.

  16. Diurnal variability in carbon and nitrogen pools within Chesapeake Bay and northern Gulf of Mexico: implications for future ocean color satellite sensors

    Science.gov (United States)

    Mannino, A.; Novak, M. G.; Tzortziou, M.; Salisbury, J.

    2016-02-01

    Relative to their areal extent, estuaries and coastal ocean ecosystems contribute disproportionately more to global biogeochemical cycling of carbon, nitrogen and other elements compared to the open ocean. Applying ocean color satellite data to study biological and biogeochemical processes within coastal ecosystems is challenging due to the complex mixtures of aquatic constituents derived from terrestrial, anthropogenic, and marine sources, human-impacted atmospheric properties, presence of clouds during satellite overpass, fine-scale spatial gradients, and time-varying processes on diurnal scales that cannot be resolved with current sensors. On diurnal scales, biological, photochemical, and biogeochemical processes are regulated by the variation in solar radiation. Other physical factors, such as tides, river discharge, estuarine and coastal ocean circulation, wind-driven mixing, etc., impart further variability on biological and biogeochemical processes on diurnal to multi-day time scales. Efforts to determine the temporal frequency required from a NASA GEO-CAPE ocean color satellite sensor to discern diurnal variability C and N stocks, fluxes and productivity culminated in field campaigns in the Chesapeake Bay and northern Gulf of Mexico. Near-surface drogues were released and tracked in quasi-lagrangian space to monitor hourly changes in community production, C and N stocks, and optical properties. While only small diurnal changes were observed in dissolved organic carbon (DOC) and colored dissolved organic matter (CDOM) absorption in Chesapeake Bay, substantial variation in particulate organic carbon (POC) and nitrogen (PN), chlorophyll-a, and inorganic nitrogen (DIN) were measured. Similar or greater diurnal changes in POC, PN, chlorophyll-a and DIN were found in Gulf of Mexico nearshore and offshore sites. These results suggest that satellite observations at hourly frequency are desirable to capture diurnal variability in carbon and nitrogen stocks, fluxes

  17. Short-term variability and mass loss in Be stars. II. Physical taxonomy of photometric variability observed by the Kepler spacecraft

    Science.gov (United States)

    Rivinius, Th.; Baade, D.; Carciofi, A. C.

    2016-09-01

    Context. Classical Be stars have been established as pulsating stars. Space-based photometric monitoring missions contributed significantly to that result. However, whether Be stars are just rapidly rotating SPB or β Cep stars, or whether they have to be understood differently, remains debated in the view of their highly complex power spectra. Aims: Kepler data of three known Be stars are re-visited to establish their pulsational nature and assess the properties of additional, non-pulsational variations. The three program stars turned out to be one inactive Be star, one active, continuously outbursting Be star, and one Be star transiting from a non-outbursting into an outbursting phase, thus forming an excellent sample to distill properties of Be stars in the various phases of their life-cycle. Methods: The Kepler data was first cleaned from any long-term variability with Lomb-Scargle based pre-whitening. Then a Lomb-Scargle analysis of the remaining short-term variations was compared to a wavelet analysis of the cleaned data. This offers a new view on the variability, as it enables us to see the temporal evolution of the variability and phase relations between supposed beating phenomena, which are typically not visualized in a Lomb-Scargle analysis. Results: The short-term photometric variability of Be stars must be disentangled into a stellar and a circumstellar part. The stellar part is on the whole not different from what is seen in non-Be stars. However, some of the observed phenomena might be to be due to resonant mode coupling, a mechanism not typically considered for B-type stars. Short-term circumstellar variability comes in the form of either a group of relatively well-defined, short-lived frequencies during outbursts, which are called Štefl frequencies, and broad bumps in the power spectra, indicating aperiodic variability on a time scale similar to typical low-order g-mode pulsation frequencies, rather than true periodicity. Conclusions: From a

  18. Study of the diurnal time variability of δ15 N and δ13 C in domestic sewage of Piracicaba city (Sao Paulo State, Brazil)

    International Nuclear Information System (INIS)

    Evangelista, Ricardo A.O.; Bortoletto Junior, Milton J.; Mortatti, Jefferson

    2002-01-01

    Diurnal variability concentrations and δ 13 C of DOC (dissolved organic carbon), DTC (dissolved total carbon) and POC (particulate organic carbon) as well as concentrations and δ 13 N of NH 4 + and PON (particulate organic nitrogen) have been measured using a ANCA-SL mass spectrometry in three points of raw sewage inputs within Piracicaba river. The results shows an important variability in the isotopic signatures and concentrations of the nitrogen and carbon forms during the diurnal period that can be successfully used to characterize and to distinguish three types of investigated effluents. (author)

  19. Global Structures and Multi-Temporal Variabilities of MLT Migrating Diurnal Tide

    International Nuclear Information System (INIS)

    Ze-Yu, Chen; Da-Ren, Lu

    2008-01-01

    Migrating diurnal tide in the MLT region is examined by the application of Hough mode decomposition with the tide delineated from the SABER/TIMED temperatures over 2002-2006. The decomposition results show that in the height range 60-100 km, the (1, 1) mode is the most predominant among eight leading Hough modes including four propagating and four trapped modes. It exhibits a sustained maximum at 97 km and significant semi-annual oscillation. Additionally, a novel feature of inter-annual variation with period of about two years is clearly seen in the (1, 1) mode, e.g., repeated maxima are seen at the March equinox of 2002, 2004 and 2006, respectively. This feature is further manifested by the tidal amplitudes in the height range 70-100 km in the height-time cross-section at the equator. It is likely of the QBO as the height range just coincides to where the zonal mean zonal winds derived by using the UARS data exhibiting the QBO. The other results show that the (1, 2) mode is important at < 80km exhibiting comparable amplitude to that of the (1, 1) mode, and in particular the nearly anti-correlation with the (1, 1) mode. The tide at about 85 km is suggested of rather complex as the four trapped modes exhibit maximum at these heights, which indicates the presence of local excitations or sources at below

  20. On the influence of cloud fraction diurnal cycle and sub-grid cloud optical thickness variability on all-sky direct aerosol radiative forcing

    International Nuclear Information System (INIS)

    Min, Min; Zhang, Zhibo

    2014-01-01

    The objective of this study is to understand how cloud fraction diurnal cycle and sub-grid cloud optical thickness variability influence the all-sky direct aerosol radiative forcing (DARF). We focus on the southeast Atlantic region where transported smoke is often observed above low-level water clouds during burning seasons. We use the CALIOP observations to derive the optical properties of aerosols. We developed two diurnal cloud fraction variation models. One is based on sinusoidal fitting of MODIS observations from Terra and Aqua satellites. The other is based on high-temporal frequency diurnal cloud fraction observations from SEVIRI on board of geostationary satellite. Both models indicate a strong cloud fraction diurnal cycle over the southeast Atlantic region. Sensitivity studies indicate that using a constant cloud fraction corresponding to Aqua local equatorial crossing time (1:30 PM) generally leads to an underestimated (less positive) diurnal mean DARF even if solar diurnal variation is considered. Using cloud fraction corresponding to Terra local equatorial crossing time (10:30 AM) generally leads overestimation. The biases are a typically around 10–20%, but up to more than 50%. The influence of sub-grid cloud optical thickness variability on DARF is studied utilizing the cloud optical thickness histogram available in MODIS Level-3 daily data. Similar to previous studies, we found the above-cloud smoke in the southeast Atlantic region has a strong warming effect at the top of the atmosphere. However, because of the plane-parallel albedo bias the warming effect of above-cloud smoke could be significantly overestimated if the grid-mean, instead of the full histogram, of cloud optical thickness is used in the computation. This bias generally increases with increasing above-cloud aerosol optical thickness and sub-grid cloud optical thickness inhomogeneity. Our results suggest that the cloud diurnal cycle and sub-grid cloud variability are important factors

  1. Diurnal variability and biogeochemical reactivity of mercury species in an extreme high-altitude lake ecosystem of the Bolivian Altiplano.

    Science.gov (United States)

    Alanoca, L; Amouroux, D; Monperrus, M; Tessier, E; Goni, M; Guyoneaud, R; Acha, D; Gassie, C; Audry, S; Garcia, M E; Quintanilla, J; Point, D

    2016-04-01

    Methylation and demethylation represent major transformation pathways regulating the net production of methylmercury (MMHg). Very few studies have documented Hg reactivity and transformation in extreme high-altitude lake ecosystems. Mercury (Hg) species concentrations (IHg, MMHg, Hg°, and DMHg) and in situ Hg methylation (M) and MMHg demethylation (D) potentials were determined in water, sediment, floating organic aggregates, and periphyton compartments of a shallow productive Lake of the Bolivian Altiplano (Uru Uru Lake, 3686 m). Samples were collected during late dry season (October 2010) and late wet season (May 2011) at a north (NS) and a south (SS) site of the lake, respectively. Mercury species concentrations exhibited significant diurnal variability as influenced by the strong diurnal biogeochemical gradients. Particularly high methylated mercury concentrations (0.2 to 4.5 ng L(-1) for MMHgT) were determined in the water column evidencing important Hg methylation in this ecosystem. Methylation and D potentials range were, respectively, production in both water (up to 0.45 ng MMHg L(-1) day(-1)) and sediment compartments (2.0 to 19.7 ng MMHg g(-1) day(-1)). While the sediment compartment appears to represent a major source of MMHg in this shallow ecosystem, floating organic aggregates (dry season, SS) and Totora's periphyton (wet season, NS) were found to act as a significant source (5.8 ng MMHg g(-1) day(-1)) and a sink (-2.1 ng MMHg g(-1) day(-1)) of MMHg, respectively. This work demonstrates that high-altitude productive lake ecosystems can promote MMHg formation in various compartments supporting recent observations of high Hg contents in fish and water birds.

  2. The Tokar Gap Jet: Regional Circulation, Diurnal Variability, and Moisture Transport Based on Numerical Simulations

    KAUST Repository

    Davis, Shannon R.; Pratt, Lawrence J.; Jiang, Houshuo

    2015-01-01

    The structure, variability, and regional connectivity of the Tokar Gap jet (TGJ) are described using WRF Model analyses and supporting atmospheric datasets from the East African–Red Sea–Arabian Peninsula (EARSAP) region during summer 2008. Sources

  3. Assessing the sources and magnitude of diurnal nitrate variability in the San Joaquin River (California) with an in situ optical nitrate sensor and dual nitrate isotopes

    Science.gov (United States)

    Pellerin, Brian A.; Downing, Bryan D.; Kendall, Carol; Dahlgren, Randy A.; Kraus, Tamara E.C.; Saraceno, John Franco; Spencer, Robert G. M.; Bergamaschi, Brian A.

    2009-01-01

    1. We investigated diurnal nitrate (NO3−) concentration variability in the San Joaquin River using an in situ optical NO3− sensor and discrete sampling during a 5‐day summer period characterized by high algal productivity. Dual NO3− isotopes (δ15NNO3 and δ18ONO3) and dissolved oxygen isotopes (δ18ODO) were measured over 2 days to assess NO3− sources and biogeochemical controls over diurnal time‐scales.2. Concerted temporal patterns of dissolved oxygen (DO) concentrations and δ18ODOwere consistent with photosynthesis, respiration and atmospheric O2 exchange, providing evidence of diurnal biological processes independent of river discharge.3. Surface water NO3− concentrations varied by up to 22% over a single diurnal cycle and up to 31% over the 5‐day study, but did not reveal concerted diurnal patterns at a frequency comparable to DO concentrations. The decoupling of δ15NNO3 and δ18ONO3isotopes suggests that algal assimilation and denitrification are not major processes controlling diurnal NO3− variability in the San Joaquin River during the study. The lack of a clear explanation for NO3− variability likely reflects a combination of riverine biological processes and time‐varying physical transport of NO3− from upstream agricultural drains to the mainstem San Joaquin River.4. The application of an in situ optical NO3− sensor along with discrete samples provides a view into the fine temporal structure of hydrochemical data and may allow for greater accuracy in pollution assessment.

  4. Diurnal variability of upper ocean temperature and heat budget in the southern Bay of Bengal during October-November, 1998 (BOBMEX-Pilot)

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, V.S.N.; RameshBabu, V.; Rao, L.V.G.; Prabhu, C.V.; Tilvi, V.

    °N locations along 87°E during October -- November, 1998 under BOBMEX-Pilot programme. These data have been analysed to examine the diurnal variability of upper oceanic heat budget and to estimate the eddy diffusivity coefficient of heat in the upper...

  5. Diurnal variability of heat fluxes and heat content at a few locations off central east coast of India during April 1989

    Digital Repository Service at National Institute of Oceanography (India)

    Sadhuram, Y.; Rao, B.P.; Rao, V.S.; Rao, T.V.N.

    Diurnal variability of surface wind speed, net heat exchange, sea surface temperature, vertical thermal structure and heat content at three locations, viz., station A (17 degrees 59'N, 83 degrees 53.9'E), station B (17 degrees 00'N, 82 degrees 32...

  6. Preliminary results from the ESA STSE project on SST diurnal variability, its regional extent and implications in atmospheric modelling (SSTDV:R.EX.–IM.A.M.)

    DEFF Research Database (Denmark)

    Karagali, Ioanna; Hasager, Charlotte Bay; Høyer, Jacob L.

    2013-01-01

    This study presents some preliminary results of the ESA Support To Science Element (STSE) funded project on the Diurnal Variability of the Sea Surface Temperature, regarding its Regional Extend and Implications in Atmospheric Modelling (SSTDV:R.EX.–IM.A.M.). Comparisons of SEVIRI SST with AATSR...

  7. BINARY CENTRAL STARS OF PLANETARY NEBULAE DISCOVERED THROUGH PHOTOMETRIC VARIABILITY. II. MODELING THE CENTRAL STARS OF NGC 6026 AND NGC 6337

    International Nuclear Information System (INIS)

    Hillwig, Todd C.; Bond, Howard E.; Afsar, Melike; De Marco, Orsola

    2010-01-01

    Close-binary central stars of planetary nebulae (CSPNe) provide an opportunity to explore the evolution of PNe, their shaping, and the evolution of binary systems undergoing a common-envelope phase. Here, we present the results of time-resolved photometry of the binary central stars (CSs) of the PNe NGC 6026 and NGC 6337 as well as time-resolved spectroscopy of the CS of NGC 6026. The results of a period analysis give an orbital period of 0.528086(4) days for NGC 6026 and a photometric period of 0.1734742(5) days for NGC 6337. In the case of NGC 6337, it appears that the photometric period reflects the orbital period and that the variability is the result of the irradiated hemisphere of a cool companion. The inclination of the thin PN ring is nearly face-on. Our modeled inclination range for the close central binary includes nearly face-on alignments and provides evidence for a direct binary-nebular shaping connection. For NGC 6026, however, the radial-velocity curve shows that the orbital period is twice the photometric period. In this case, the photometric variability is due to an ellipsoidal effect in which the CS nearly fills its Roche lobe and the companion is most likely a hot white dwarf. NGC 6026 then is the third PN with a confirmed central binary where the companion is compact. Based on the data and modeling using a Wilson-Devinney code, we discuss the physical parameters of the two systems and how they relate to the known sample of close-binary CSs, which comprise 15%-20% of all PNe.

  8. Seasonal and diurnal variability of the meteor flux at high latitudes observed using PFISR

    Science.gov (United States)

    Sparks, J. J.; Janches, D.; Nicolls, M. J.; Heinselman, C. J.

    2009-05-01

    We report in this and a companion paper [Fentzke, J.T., Janches, D., Sparks, J.J., 2008. Latitudinal and seasonal variability of the micrometeor input function: A study using model predictions and observations from Arecibo and PFISR. Journal of Atmospheric and Solar-Terrestrial Physics, this issue, doi:10.1016/j.jastp.2008.07.015] a complete seasonal study of the micrometeor input function (MIF) at high latitudes using meteor head-echo radar observations performed with the Poker Flat Incoherent Scatter Radar (PFISR). This flux is responsible for a number of atmospheric phenomena; for example, it could be the source of meteoric smoke that is thought to act as condensation nuclei in the formation of ice particles in the polar mesosphere. The observations presented here were performed for full 24-h periods near the summer and winter solstices and spring and autumn equinoxes, times at which the seasonal variability of the MIF is predicted to be large at high latitudes [Janches, D., Heinselman, C.J., Chau, J.L., Chandran, A., Woodman, R., 2006. Modeling of the micrometeor input function in the upper atmosphere observed by High Power and Large Aperture Radars, JGR, 11, A07317, doi:10.1029/2006JA011628]. Precise altitude and radar instantaneous line-of-sight (radial) Doppler velocity information are obtained for each of the hundreds of events detected every day. We show that meteor rates, altitude, and radial velocity distributions have a large seasonal dependence. This seasonal variability can be explained by a change in the relative location of the meteoroid sources with respect to the observer. Our results show that the meteor flux into the upper atmosphere is strongly anisotropic and its characteristics must be accounted for when including this flux into models attempting to explain related aeronomical phenomena. In addition, the measured acceleration and received signal strength distribution do not seem to depend on season; which may suggest that these observed

  9. Interannual and Diurnal Variability in Water Ice Clouds Observed from MSL Over Two Martian Years

    Science.gov (United States)

    Kloos, J. L.; Moores, J. E.; Whiteway, J. A.; Aggarwal, M.

    2018-01-01

    We update the results of cloud imaging sequences from the Mars Science Laboratory (MSL) rover Curiosity to complete two Mars years of observations (LS=160° of Mars year (MY) 31 to LS=160° of MY 33). Relatively good seasonal coverage is achieved within the study period, with just over 500 observations obtained, averaging one observation every 2-3 sols. Cloud opacity measurements are made using differential photometry and a simplified radiative transfer method. These opacity measurements are used to assess the interannual variability of the aphelion cloud belt (ACB) for MY 32 and 33. Upon accounting for a statistical bias in the data set, the variation is found to be year. Although a gap in data around local noon prevents a complete assessment, we find that cloud opacity is moderately increased in the morning hours (07:00-09:00) compared to the late afternoon (15:00-17:00).

  10. Photometric studies of two W UMa type variables in the field of distant open cluster NGC 6866

    International Nuclear Information System (INIS)

    Joshi, Yogesh Chandra; Joshi, Santosh; Jagirdar, Rukmini

    2016-01-01

    We present photometric analysis of the two W UMa type binaries identified in the field of distant open star cluster NGC 6866. Although these systems, namely ID487 and ID494, were reported by Joshi et al., a detailed study of these stars has not been carried out before. The orbital periods of these stars are found to be 0.415110±0.000001 day and 0.366709±0.000004 day, respectively. Based on the photometric and infrared colors, we find their respective spectral types to be K0 and K3. The photometric light variations of both stars show the O'Connell effect which can be explained by employing a dark spot on the secondary components. The V and I band light curves are analyzed using the Wilson-Devinney (WD) code and relations given by Gazeas which yield radii and masses for the binary components of star ID487 of R 1 = 1.24 ± 0.01 R ⊙ , R 2 = 1.11 ± 0.02 R ⊙ , and M 1 = 1.24 ± 0.02 M ⊙ , M 2 = 0.96 ± 0.05 M ⊙ and for star ID494 of R 1 = 1.22±0.02R ⊙ , R 2 = 0.81±0.01 R ⊙ , and M 1 = 1.20±0.06 M ⊙ , M 2 = 0.47±0.01 M ⊙ . (paper)

  11. Diurnal and seasonal variability in size-dependent atmospheric deposition fluxes of polycyclic aromatic hydrocarbons in an urban center

    Science.gov (United States)

    Zhang, Kai; Zhang, Bao-Zhong; Li, Shao-Meng; Zhang, Lei-Ming; Staebler, Ralf; Zeng, Eddy Y.

    2012-09-01

    Atmospheric gaseous and size-segregated particle samples were collected from urban Guangzhou at the heights of 100 and 150 m above the ground in daytime and at night in August and December 2010, and were analyzed for polycyclic aromatic hydrocarbons (PAHs). Particulate PAHs were more abundant at night than in daytime, and significantly higher in winter than in summer. The observed vertical, diurnal, and seasonal variability in the occurrences of PAH were attributed to varying meteorological conditions and atmospheric boundary layers. More than 60% of the particulate PAHs were contained in particles in the accumulation mode with an aerodynamic diameter (Dp) in the range of 0.1-1.8 μm. Different mass transfer velocities by volatilization and condensation are considered the main causes for the different particle size distributions among individual PAHs, while combustion at different temperatures and atmospheric transport were probable causes of the observed seasonal variation in the size distribution of PAHs. Based on the modeled size-dependent dry deposition velocities, daily mean dry deposition fluxes of particulate PAHs ranged from 604 to 1190 ng m-2 d-1, with PAHs in coarse particles (Dp > 1.8 μm) accounting for 55-95% of the total fluxes. In addition, gaseous PAHs were estimated to contribute 0.6-3.1% to the total dry deposition fluxes if a conservative dry deposition velocity for gaseous species (2 × 10-4 m s-1) were used. Finally, disequilibrium phase partitioning, meteorological conditions and atmospheric transport were regarded as the main reasons for the variances in dry deposition velocities of individual PAHs.

  12. Diurnal variability in riverine dissolved organic matter composition determined by in situ optical measurement in the San Joaquin River (California, USA)

    Science.gov (United States)

    Spencer, R.G.M.; Pellerin, B.A.; Bergamaschi, B.A.; Downing, B.D.; Kraus, T.E.C.; Smart, D.R.; Dahlgren, R.A.; Hernes, P.J.

    2007-01-01

    Dissolved organic matter (DOM) concentration and composition in riverine and stream systems are known to vary with hydrological and productivity cycles over the annual and interannual time scales. Rivers are commonly perceived as homogeneous with respect to DOM concentration and composition, particularly under steady flow conditions over short time periods. However, few studies have evaluated the impact of short term variability ( DOC) measurement alone. The in situ optical measurements described in this study clearly showed for the first time diurnal variations in DOM measurements, which have previously been related to both composition and concentration, even though diurnal changes were not well reflected in bulk DOC concentrations. An apparent asynchronous trend of DOM absorbance and chlorophyll-a in comparison to chromophoric dissolved organic matter (CDOM) fluorescence and spectral slope S290-350 suggests that no one specific CDOM spectrophotometric measurement explains absolutely DOM diurnal variation in this system; the measurement of multiple optical parameters is therefore recommended. The observed diurnal changes in DOM composition, measured by in situ optical instrumentation likely reflect both photochemical and biologically-mediated processes. The results of this study highlight that short-term variability in DOM composition may complicate trends for studies aiming to distinguish different DOM sources in riverine systems and emphasizes the importance of sampling specific study sites to be compared at the same time of day. The utilization of in situ optical technology allows short-term variability in DOM dynamics to be monitored and serves to increase our understanding of its processing and fundamental role in the aquatic environment. Copyright ?? 2007 John Wiley & Sons, Ltd.

  13. A FIVE-YEAR SPECTROSCOPIC AND PHOTOMETRIC CAMPAIGN ON THE PROTOTYPICAL α CYGNI VARIABLE AND A-TYPE SUPERGIANT STAR DENEB

    International Nuclear Information System (INIS)

    Richardson, N. D.; Morrison, N. D.; Kryukova, E. E.; Adelman, S. J.

    2011-01-01

    Deneb is often considered the prototypical A-type supergiant and is one of the visually most luminous stars in the Galaxy. A-type supergiants are potential extragalactic distance indicators, but the variability of these stars needs to be better characterized before this technique can be considered reliable. We analyzed 339 high-resolution echelle spectra of Deneb obtained over the five-year span of 1997 through 2001 as well as 370 Stroemgren photometric measurements obtained during the same time frame. Our spectroscopic analysis included dynamical spectra of the Hα profile, Hα equivalent widths, and radial velocities measured from Si II λλ 6347, 6371. Time-series analysis reveals no obvious cyclic behavior that proceeds through multiple observing seasons, although we found a suspected 40 day period in two, non-consecutive observing seasons. Some correlations are found between photometric and radial velocity data sets and suggest radial pulsations at two epochs. No correlation is found between the variability of the Hα profiles and that of the radial velocities or the photometry. Lucy found evidence that Deneb was a long-period single-lined spectroscopic binary star, but our data set shows no evidence for radial velocity variations caused by a binary companion.

  14. Spectral and photometric observations of fast irregular variables. 3. VX Cas, UX Ori, BN Ori and WW Vul - results of U,B,V,J,H,K,L photometry

    International Nuclear Information System (INIS)

    Kolotilov, E.A.; Zajtseva, G.V.; Chenavrin, V.I.

    1977-01-01

    In the 1975-76 period photometric observations of the variable stars VX Cas, BN Ori and WW Vul in the optical (U,B,V) and infrared (J,H,K,L) spectral ranges have been conducted on the 60-cm and 125-cm reflector at the GAISh station in the Crimea. In most cases the optical and infrared measurements were carried out concurrently for each star. The photometric behavior of the variables during the observation period is described and, where possible, radiation variabilities in the different spectra ranges are compared

  15. Change in diurnal variations of meteorological variables induced by anthropogenic aerosols over the North China Plain in summer 2008

    Science.gov (United States)

    Gao, Yi; Zhang, Meigen; Liu, Xiaohong; Wang, Lili

    2016-04-01

    This study investigates the impacts of all anthropogenic aerosols and anthropogenic black carbon (BC) on the diurnal variations of meteorological variables in the atmospheric boundary layer over the North China Plain (NCP) during June to August 2008, using a coupled meteorology and chemistry model (WRF-Chem). The results of the ensemble numerical experiments show that surface air temperature decreases by about 0.6 to 1.2 K with the maximum decrease over the Beijing urban area and the southern part of Hebei province, and the surface relative humidity (RH) increases by 2-4 % owing to all anthropogenic aerosols. On the contrary, anthropogenic BC induces a small change of temperature and RH at surface. Averaged for Beijing, Tianjin, and Hebei province (BTH region) and High Particle Concentration (HPC) periods when PM2.5 surface concentration is more than 60 μg m-3 and daily AOD is more than 0.9, all anthropogenic aerosols decrease air temperature under 850 hPa and increase it between 500 and 850 hPa, while anthropogenic BC increases it for whole atmosphere. The maximum changes occur at 08:00-20:00 (local time). Aerosol-induced surface energy and diabatic heating change leads to a cooling at the surface and in the lower atmosphere and a warming in the middle troposphere at 08:00-17:00, with reversed effects at 20:00-05:00. BC cools the atmosphere at the surface and warms the atmosphere above for the whole day. As a result, the equivalent potential temperature profile change shows that the lower atmosphere is more stable at 08:00 and 14:00. All anthropogenic aerosols decrease the surface wind speed by 20-60 %, while anthropogenic BC decreases the wind speed by 10-40 % over the NCP with the maximum decrease at 08:00. The aerosol-induced stabilization of the lower atmosphere favors the accumulation of air pollutants and thus contributes to deterioration of visibility and fog-haze events.

  16. Photometric Uncertainties

    Science.gov (United States)

    Zou, Xiao-Duan; Li, Jian-Yang; Clark, Beth Ellen; Golish, Dathon

    2018-01-01

    The OSIRIS-REx spacecraft, launched in September, 2016, will study the asteroid Bennu and return a sample from its surface to Earth in 2023. Bennu is a near-Earth carbonaceous asteroid which will provide insight into the formation and evolution of the solar system. OSIRIS-REx will first approach Bennu in August 2018 and will study the asteroid for approximately two years before sampling. OSIRIS-REx will develop its photometric model (including Lommel-Seelinger, ROLO, McEwen, Minnaert and Akimov) of Bennu with OCAM and OVIRS during the Detailed Survey mission phase. The model developed during this phase will be used to photometrically correct the OCAM and OVIRS data.Here we present the analysis of the error for the photometric corrections. Based on our testing data sets, we find:1. The model uncertainties is only correct when we use the covariance matrix to calculate, because the parameters are highly correlated.2. No evidence of domination of any parameter in each model.3. And both model error and the data error contribute to the final correction error comparably.4. We tested the uncertainty module on fake and real data sets, and find that model performance depends on the data coverage and data quality. These tests gave us a better understanding of how different model behave in different case.5. L-S model is more reliable than others. Maybe because the simulated data are based on L-S model. However, the test on real data (SPDIF) does show slight advantage of L-S, too. ROLO is not reliable to use when calculating bond albedo. The uncertainty of McEwen model is big in most cases. Akimov performs unphysical on SOPIE 1 data.6. Better use L-S as our default choice, this conclusion is based mainly on our test on SOPIE data and IPDIF.

  17. The influence of sea- and land-breeze circulations on the diurnal variability in precipitation over a tropical island

    Directory of Open Access Journals (Sweden)

    L. Zhu

    2017-11-01

    Full Text Available This study examines the diurnal variation in precipitation over Hainan Island in the South China Sea using gauge observations from 1951 to 2012 and Climate Prediction Center MORPHing technique (CMORPH satellite estimates from 2006 to 2015, as well as numerical simulations. The simulations are the first to use climatological mean initial and lateral boundary conditions to study the dynamic and thermodynamic processes (and the impacts of land–sea breeze circulations that control the rainfall distribution and climatology. Precipitation is most significant from April to October and exhibits a strong diurnal cycle resulting from land–sea breeze circulations. More than 60 % of the total annual precipitation over the island is attributable to the diurnal cycle with a significant monthly variability. The CMORPH and gauge datasets agree well, except that the CMORPH data underestimate precipitation and have a 1 h peak delay. The diurnal cycle of the rainfall and the related land–sea breeze circulations during May and June were well captured by convection-permitting numerical simulations with the Weather Research and Forecasting (WRF model, which were initiated from a 10-year average ERA-Interim reanalysis. The simulations have a slight overestimation of rainfall amounts and a 1 h delay in peak rainfall time. The diurnal cycle of precipitation is driven by the occurrence of moist convection around noontime owing to low-level convergence associated with the sea-breeze circulations. The precipitation intensifies rapidly thereafter and peaks in the afternoon with the collisions of sea-breeze fronts from different sides of the island. Cold pools of the convective storms contribute to the inland propagation of the sea breeze. Generally, precipitation dissipates quickly in the evening due to the cooling and stabilization of the lower troposphere and decrease of boundary layer moisture. Interestingly, the rather high island orography is not a

  18. Impact of atmospheric boundary layer depth variability and wind reversal on the diurnal variability of aerosol concentration at a valley site

    Energy Technology Data Exchange (ETDEWEB)

    Pal, S., E-mail: sp5hd@Virginia.EDU; Lee, T.R.; Phelps, S.; De Wekker, S.F.J.

    2014-10-15

    concentration variability • Only accumulation mode particles are affected by boundary layer dilution effect. • Effect of wind reversal in a valley on the diurnal cycle of particle concentrations. • Decreasing trend in the boundary layer depths resulted in an increasing trend in aerosol concentration. • Effect of boundary layer depth growth rate on aerosol concentration.

  19. Spatial Variability of the Background Diurnal Cycle of Deep Convection around the GoAmazon2014/5 Field Campaign Sites

    Energy Technology Data Exchange (ETDEWEB)

    Burleyson, Casey D.; Feng, Zhe; Hagos, Samson M.; Fast, Jerome; Machado, Luiz A. T.; Martin, Scot T.

    2016-07-01

    The Amazon rainforest is one of a few regions of the world where continental tropical deep convection occurs. The Amazon’s isolation makes it challenging to observe, but also creates a unique natural laboratory to study anthropogenic impacts on clouds and precipitation in an otherwise pristine environment. Extensive measurements were made upwind and downwind of the large city of Manaus, Brazil during the Observations and Modeling of the Green Ocean Amazon 2014-2015 (GoAmazon2014/5) field campaign. In this study, 15 years of high-resolution satellite data are analyzed to examine the spatial and diurnal variability of convection occurring around the GoAmazon2014/5 sites. Interpretation of anthropogenic differences between the upwind (T0) and downwind (T1-T3) sites is complicated by naturally-occurring spatial variability between the sites. During the rainy season, the inland propagation of the previous day’s sea-breeze front happens to be in phase with the background diurnal cycle near Manaus, but is out of phase elsewhere. Enhanced convergence between the river-breezes and the easterly trade winds generates up to 10% more frequent deep convection at the GoAmazon2014/5 sites east of the river (T0a, T0t/k, and T1) compared to the T3 site which was located near the western bank. In general, the annual and diurnal cycles during 2014 were representative of the 2000-2013 distributions. The only exceptions were in March when the monthly mean rainrate was above the 95th percentile and September when both rain frequency and intensity were suppressed. The natural spatial variability must be accounted for before interpreting anthropogenically-induced differences among the GoAmazon2014/5 sites.

  20. Distinct patterns in the diurnal and seasonal variability in four components of soil respiration in a temperate forest under free-air CO2 enrichment

    Directory of Open Access Journals (Sweden)

    M. A. Gonzalez-Meler

    2011-10-01

    Full Text Available Soil respiration (RS is a major flux in the global carbon (C cycle. Responses of RS to changing environmental conditions may exert a strong control on the residence time of C in terrestrial ecosystems and in turn influence the atmospheric concentration of greenhouse gases. Soil respiration consists of several components oxidizing soil C from different pools, age and chemistry. The mechanisms underlying the temporal variability of RS components are poorly understood. In this study, we used the long-term whole-ecosystem 13C tracer at the Duke Forest Free Air CO2 Enrichment site to separate forest RS into its autotrophic (RR and heterotrophic components (RH. The contribution of RH to RS was further partitioned into litter decomposition (RL, and decomposition of soil organic matter (RSOM of two age classes – up to 8 yr old and SOM older than 8 yr. Soil respiration was generally dominated by RSOM during the growing season (44% of daytime RS, especially at night. The contribution of heterotrophic respiration (RSOM and RL to RS was not constant, indicating that the seasonal variability in RR alone cannot explain seasonal variation in RS. Although there was no diurnal variability in RS, there were significant compensatory differences in the contribution of individual RS components to daytime and nighttime rates. The average contribution of RSOM to RS was greater at night (54% than during the day (44%. The average contribution of RR to total RS was ~30% during the day and ~34% during the night. In contrast, RL constituted 26% of RS during the day and only 12% at night. About 95% of the decomposition of soil C older than 8 yr (Rpre-tr originated from RSOM and showed more pronounced and consistent diurnal variability than any other RS component; nighttime rates were on average 29% higher than daytime rates. In contrast, the decomposition of more recent, post-treatment C (Rpre-tr did not vary diurnally. None of the diurnal variations in components of RH

  1. BINARY CENTRAL STARS OF PLANETARY NEBULAE DISCOVERED THROUGH PHOTOMETRIC VARIABILITY. IV. THE CENTRAL STARS OF HaTr 4 AND Hf 2-2

    Energy Technology Data Exchange (ETDEWEB)

    Hillwig, Todd C.; Schaub, S. C. [Department of Physics and Astronomy, Valparaiso University, Valparaiso, IN 46383 (United States); Bond, Howard E. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Frew, David J. [Department of Physics, The University of Hong Kong, Pokfulam Road (Hong Kong); Bodman, Eva H. L., E-mail: todd.hillwig@valpo.edu [Southeastern Association for Research in Astronomy (SARA) (United States)

    2016-08-01

    We explore the photometrically variable central stars of the planetary nebulae HaTr 4 and Hf 2-2. Both have been classified as close binary star systems previously based on their light curves alone. Here, we present additional arguments and data confirming the identification of both as close binaries with an irradiated cool companion to the hot central star. We include updated light curves, orbital periods, and preliminary binary modeling for both systems. We also identify for the first time the central star of HaTr 4 as an eclipsing binary. Neither system has been well studied in the past, but we utilize the small amount of existing data to limit possible binary parameters, including system inclination. These parameters are then compared to nebular parameters to further our knowledge of the relationship between binary central stars of planetary nebulae and nebular shaping and ejection.

  2. VizieR Online Data Catalog: Photometric variability of BeSS-KELT stars (Labadie-Bartz+, 2017)

    Science.gov (United States)

    Labadie-Bartz, J.; Pepper, J.; McSwain, M. V.; Bjorkman, J. E.; Bjorkman, K. S.; Lund, M. B.; Rodriguez, J. E.; Stassun, K. G.; Stevens, D. J.; James, D. J.; Kuhn, R. B.; Siverd, R. J.; Beatty, T. G.

    2018-04-01

    Kilodegree Extremely Little Telescope (KELT) is a photometric survey using two small-aperture (42 mm) wide-field (26°x26°) telescopes, with a northern location at Winer Observatory in Arizona in the United States, and a southern location at the South African Astronomical Observatory near Sutherland, South Africa. The Be Star Spectra (BeSS) database is a continually updated catalog that attempts to include all known Be stars, as well as their stellar parameters. This catalog is based primarily on the catalog of classical Be stars published by Jaschek et al. (1982, Cat. III/67) but also includes more recently discovered Be stars from a variety of sources (e.g., Neiner et al. 2005ApJS..156..237N; Martayan et al. 2006A&A...445..931M). From the BeSS database, we compiled a list of all the classical Be stars with 7

  3. Assessing the diurnal variability of pharmaceutical and personal care products in a full-scale activated sludge plant

    International Nuclear Information System (INIS)

    Salgado, R.; Marques, R.; Noronha, J.P.; Mexia, J.T.; Carvalho, G.; Oehmen, A.; Reis, M.A.M.

    2011-01-01

    An intensive sampling campaign has been carried out in a municipal wastewater treatment plant (WWTP) to assess the dynamics of the influent pharmaceutical active compounds (PhAC) and musks. The mass loadings of these compounds in wastewater influents displayed contrasting diurnal variations depending on the compound. The musks and some groups of PhACs tended to follow a similar diurnal trend as compared to macropollutants, while the majority of PhACs followed either the opposite trend or no repeatable trend. The total musk loading to the WWTP was 0.74 ± 0.25 g d -1 , whereas the total PhAC mass loading was 84.7 ± 63.8 g d -1 . Unlike the PhACs, the musks displayed a high repeatability from one sampling day to the next. The range of PhAC loadings in the influent to WWTPs can vary several orders of magnitude from one day or week to the next, representing a challenge in obtaining data for steady-state modelling purposes. - Highlights: → Investigated the variations in influent wastewater pharmaceutical and musk loadings. → A high number of different pharmaceutical and musk compounds was analysed. → Many pharmaceutical groups displayed different characteristic patterns. → A representative steady-state pattern was observable for musks, not pharmaceuticals. → The results are relevant to the design of sampling campaigns for modelling purposes. - The diurnal variations of pharmaceuticals and musks were studied in an activated sludge plant, where the loadings of the musks were more repeatable than the pharmaceuticals.

  4. Diurnal blood pressure changes.

    Science.gov (United States)

    Asayama, Kei; Satoh, Michihiro; Kikuya, Masahiro

    2018-05-23

    The definition of diurnal blood pressure changes varies widely, which can be confusing. Short-term blood pressure variability during a 24-h period and the dipping status of diurnal blood pressure can be captured by ambulatory blood pressure monitoring, and these metrics are reported to have prognostic significance for cardiovascular complications. Morning blood pressure surge also indicates this risk, but its effect may be limited to populations with specific conditions. Meanwhile, the combined use of conventional office blood pressure and out-of-office blood pressure allows us to identify people with white-coat and masked hypertension. Current home devices can measure nocturnal blood pressure during sleep more conveniently than ambulatory monitoring; however, we should pay attention to blood pressure measurement conditions regardless of whether they are in a home, ambulatory, or office setting. The relatively poor reproducibility of diurnal blood pressure changes, including the nocturnal fall of blood pressure, is another underestimated issue to be addressed. Although information on diurnal blood pressure changes is expected to be used more effectively in the future, we should also keep in mind that blood pressure levels have remained central to the primary and secondary prevention of blood pressure-related cardiovascular diseases in clinical practice.

  5. Variability and trend of diurnal temperature range in China and their relationship to total cloud cover and sunshine duration

    Energy Technology Data Exchange (ETDEWEB)

    Xia, X. [Chinese Academy of Sciences, Beijing (China). LAGEO

    2013-07-01

    This study aims to investigate the effect of total cloud cover (TCC) and sunshine duration (SSD) in the variation of diurnal temperature range (DTR) in China during 1954-2009. As expected, the inter-annual variation of DTR was mainly determined by TCC. Analysis of trends of 30- year moving windows of DTR and TCC time series showed that TCC changes could account for that of DTR in some cases. However, TCC decreased during 1954-2009, which did not support DTR reduction across China. DTRs under sky conditions such as clear, cloudy and overcast showed nearly the same decreasing rate that completely accounted for the overall DTR reduction. Nevertheless, correlation between SSD and DTR was weak and not significant under clear sky conditions in which aerosol direct radiative effect should be dominant. Furthermore, 30-60% of DTR reduction was associated with DTR decrease under overcast conditions in south China. This implies that aerosol direct radiative effect appears not to be one of the main factors determining long-term changes in DTR in China. (orig.)

  6. An Experimental Comparison of the Effects of Zostera marina and Zostera japonica on the Diurnal Variability of the Carbonate System in the Context of a Pacific Northwest Estuary

    Science.gov (United States)

    Miller, C.; Love, B. A.; Yang, S.

    2016-02-01

    Atmospheric CO2 emissions are being absorbed at an unprecedented rate by the global and coastal oceans, shifting the baseline pCO2, and inducing anthropogenic ocean acidification (OA). Recent studies have highlighted the potential benefits of near-shore vegetated habitats, such as seagrass beds as carbon sinks, potentially mitigating the effects of OA for vulnerable calcifying organisms. Seagrasses are capable of raising seawater pH and CaCO3 saturation state during times of high photosynthetic activity; however, the converse occurs during periods of dark respiration, resulting in a cyclical pattern of high and low pH and saturation state. A better understanding of diurnal seagrass induced carbonate system variability is needed to determine whether seagrass beds act as refugia from OA, and if individual species differentially affect the carbonate system. We conducted experiments to compare the effects of the native Zostera marina and non-native Zostera japonica on the carbonate system. Leaf clippings were incubated at five different light intensities (including dark) and pCO2 levels, representing the range of light and pCO2 in a given day. Induced changes in dissolved inorganic carbon (DIC) via photosynthesis and respiration were measured as well as pH and alkalinity. As irradiance and concentration of bio-available inorganic carbon are the two main drivers of photosynthetic activity, our measurements of the short-term response of photosynthesis to a spectrum of pCO2 and irradiance intensity can predict the diurnal fluctuation of pH and DIC for both species. This lab study provides a mechanistic background for building complex models based on field monitoring of carbonate chemistry in seagrass communities by comparing and integrating our results with in situ measurements. Interpretation of our findings will be placed in the context of short-term seagrass response to the spatiotemporal variability of pCO2 with respect to the progression of ocean acidification.

  7. The relationship of diurnal variability and level of glycemia with structural and functional parameters of heart in patients with chronic heart failure and diabetes mellitus type 2

    Directory of Open Access Journals (Sweden)

    Виктор Денисович Сиволап

    2016-01-01

    Full Text Available An important contribution in the development of diabetes mellitus (DM complications makes not only the chronic hyperglycemia but also the intense diurnal glycemia variability (GV. The aim of research was to assess systolic and diastolic heart functions in patients with chronic heart failure (CHF of ischemic genesis on the background of DM type 2 depending on GV profile and the mean level of glycemia during the last 3 month.Methods: There were examined 65 patients who were divided into groups twice on the different categoric indicators. The first indicator – an intensity of glycemia profile (GP variability, the second – the mean calculated level of glucose concentration in patients during the last 3 month. All patients underwent dopplerechocardiography, the standard declination and the coefficient of GP variations were calculated. An assessment of reliability of the results of statistic study was carried out by nonparametric method.Results: in patients with the high GP variability was detected the reliably greater size of the left atrium, decrease of the left ventricle output fraction, tendency to the transition of diastolic dysfunction from the I type to the II one comparing with the group with low GP variability. There was not revealed any reliable difference between groups or correlative connection of the mean level of glycemia with parameters that characterize contractility and diastolic myocardium function.Conclusions: There was revealed the negative influence of the high glycemia variability on systolic and diastolic heart functions, left atrium size and there was not revealed any reliable influence of the mean level of glycemia on cardiohemodynamics

  8. Effects of Diurnal Variation and Caffeine Consumption on Test of Variables of Attention (TOVA) Performance in Healthy Young Adults

    Science.gov (United States)

    Hunt, Melissa G.; Momjian, Ani J.; Wong, Keri K.

    2011-01-01

    The Test of Variables of Attention (TOVA) is a continuous performance test (CPT) that assesses attention, impulsivity, and processing speed. CPTs are used in the assessment of attention-deficit/hyperactivity disorder (ADHD) in children, but more young adults are being assessed for ADHD as well. The TOVA norms are based on a standardization sample…

  9. Satellite Photometric Error Determination

    Science.gov (United States)

    2015-10-18

    Satellite Photometric Error Determination Tamara E. Payne, Philip J. Castro, Stephen A. Gregory Applied Optimization 714 East Monument Ave, Suite...advocate the adoption of new techniques based on in-frame photometric calibrations enabled by newly available all-sky star catalogs that contain highly...filter systems will likely be supplanted by the Sloan based filter systems. The Johnson photometric system is a set of filters in the optical

  10. Diurnal Variation and Twenty-Four Hour Sleep Deprivation Do Not Alter Supine Heart Rate Variability in Healthy Male Young Adults.

    Directory of Open Access Journals (Sweden)

    Daniel S Quintana

    Full Text Available Heart rate variability (HRV has become an increasingly popular index of cardiac autonomic control in the biobehavioral sciences due to its relationship with mental illness and cognitive traits. However, the intraindividual stability of HRV in response to sleep and diurnal disturbances, which are commonly reported in mental illness, and its relationship with executive function are not well understood. Here, in 40 healthy adult males we calculated high frequency HRV-an index of parasympathetic nervous system (PNS activity-using pulse oximetry during brain imaging, and assessed attentional and executive function performance in a subsequent behavioral test session at three time points: morning, evening, and the following morning. Twenty participants were randomly selected for total sleep deprivation whereas the other 20 participants slept as normal. Sleep deprivation and morning-to-night variation did not influence high frequency HRV at either a group or individual level; however, sleep deprivation abolished the relationship between orienting attention performance and HRV. We conclude that a day of wake and a night of laboratory-induced sleep deprivation do not alter supine high frequency HRV in young healthy male adults.

  11. Diurnal Evolution and Annual Variability of Boundary Layer Height in the Columbia River Gorge through the `Eye' of Wind Profiling Radars

    Science.gov (United States)

    Bianco, L.; Djalalova, I.; Konopleva-Akish, E.; Kenyon, J.; Olson, J. B.; Wilczak, J. M.

    2016-12-01

    The Second Wind Forecast Improvement Project (WFIP2) is a DoE- and NOAA-sponsored program whose goal is to improve the accuracy of numerical weather prediction (NWP) forecasts in complex terrain. WFIP2 consists of an 18-month (October 2015 - March 2017) field campaign held in the Columbia River basin, in the Pacific Northwest of the U.S. As part of WFIP2 a large suite of in-situ and remote sensing instrumentation has been deployed, including, among several others, a network of eight 915-MHz wind profiling radars (WPRs) equipped with radio acoustic sounding systems (RASSs), and many surface meteorological stations. The diurnal evolution and annual variability of boundary layer height in the area of WFIP2 will be investigated through the `eye' of WPRs, employing state-of-the-art automated algorithms, based on fuzzy logic and artificial intelligence. The results will be used to evaluate possible errors in NWP models in this area of complex terrain.

  12. Diurnal Variability in Chlorophyll-a, Carotenoids, CDOM and SO42− Intensity of Offshore Seawater Detected by an Underwater Fluorescence-Raman Spectral System

    Science.gov (United States)

    Chen, Jing; Ye, Wangquan; Guo, Jinjia; Luo, Zhao; Li, Ying

    2016-01-01

    A newly developed integrated fluorescence-Raman spectral system (λex = 532 nm) for detecting Chlorophyll-a (chl-a), Chromophoric Dissolved Organic Matter (CDOM), carotenoids and SO42− in situ was used to successfully investigate the diurnal variability of all above. Simultaneously using the integration of fluorescence spectroscopy and Raman spectroscopy techniques provided comprehensive marine information due to the complementarity between the different excitation mechanisms and different selection rules. The investigation took place in offshore seawater of the Yellow Sea (36°05′40′′ N, 120°31′32′′ E) in October 2014. To detect chl-a, CDOM, carotenoids and SO42−, the fluorescence-Raman spectral system was deployed. It was found that troughs of chl-a and CDOM fluorescence signal intensity were observed during high tides, while the signal intensity showed high values with larger fluctuations during ebb-tide. Chl-a and carotenoids were influenced by solar radiation within a day cycle by different detection techniques, as well as displaying similar and synchronous tendency. CDOM fluorescence cause interference to the measurement of SO42−. To avoid such interference, the backup Raman spectroscopy system with λex = 785 nm was employed to detect SO42− concentration on the following day. The results demonstrated that the fluorescence-Raman spectral system has great potential in detection of chl-a, carotenoids, CDOM and SO42− in the ocean. PMID:27420071

  13. Diurnal Variability in Chlorophyll-a, Carotenoids, CDOM and SO42− Intensity of Offshore Seawater Detected by an Underwater Fluorescence-Raman Spectral System

    Directory of Open Access Journals (Sweden)

    Jing Chen

    2016-07-01

    Full Text Available A newly developed integrated fluorescence-Raman spectral system (λex = 532 nm for detecting Chlorophyll-a (chl-a, Chromophoric Dissolved Organic Matter (CDOM, carotenoids and SO42− in situ was used to successfully investigate the diurnal variability of all above. Simultaneously using the integration of fluorescence spectroscopy and Raman spectroscopy techniques provided comprehensive marine information due to the complementarity between the different excitation mechanisms and different selection rules. The investigation took place in offshore seawater of the Yellow Sea (36°05′40′′ N, 120°31′32′′ E in October 2014. To detect chl-a, CDOM, carotenoids and SO42−, the fluorescence-Raman spectral system was deployed. It was found that troughs of chl-a and CDOM fluorescence signal intensity were observed during high tides, while the signal intensity showed high values with larger fluctuations during ebb-tide. Chl-a and carotenoids were influenced by solar radiation within a day cycle by different detection techniques, as well as displaying similar and synchronous tendency. CDOM fluorescence cause interference to the measurement of SO42−. To avoid such interference, the backup Raman spectroscopy system with λex = 785 nm was employed to detect SO42− concentration on the following day. The results demonstrated that the fluorescence-Raman spectral system has great potential in detection of chl-a, carotenoids, CDOM and SO42− in the ocean.

  14. Diurnal Variability in Chlorophyll-a, Carotenoids, CDOM and SO₄(2-) Intensity of Offshore Seawater Detected by an Underwater Fluorescence-Raman Spectral System.

    Science.gov (United States)

    Chen, Jing; Ye, Wangquan; Guo, Jinjia; Luo, Zhao; Li, Ying

    2016-07-13

    A newly developed integrated fluorescence-Raman spectral system (λex = 532 nm) for detecting Chlorophyll-a (chl-a), Chromophoric Dissolved Organic Matter (CDOM), carotenoids and SO₄(2-) in situ was used to successfully investigate the diurnal variability of all above. Simultaneously using the integration of fluorescence spectroscopy and Raman spectroscopy techniques provided comprehensive marine information due to the complementarity between the different excitation mechanisms and different selection rules. The investigation took place in offshore seawater of the Yellow Sea (36°05'40'' N, 120°31'32'' E) in October 2014. To detect chl-a, CDOM, carotenoids and SO₄(2-), the fluorescence-Raman spectral system was deployed. It was found that troughs of chl-a and CDOM fluorescence signal intensity were observed during high tides, while the signal intensity showed high values with larger fluctuations during ebb-tide. Chl-a and carotenoids were influenced by solar radiation within a day cycle by different detection techniques, as well as displaying similar and synchronous tendency. CDOM fluorescence cause interference to the measurement of SO₄(2-). To avoid such interference, the backup Raman spectroscopy system with λex = 785 nm was employed to detect SO₄(2-) concentration on the following day. The results demonstrated that the fluorescence-Raman spectral system has great potential in detection of chl-a, carotenoids, CDOM and SO₄(2-) in the ocean.

  15. Impact of atmospheric boundary layer depth variability and wind reversal on the diurnal variability of aerosol concentration at a valley site.

    Science.gov (United States)

    Pal, S; Lee, T R; Phelps, S; De Wekker, S F J

    2014-10-15

    The development of the atmospheric boundary layer (ABL) plays a key role in affecting the variability of atmospheric constituents such as aerosols, greenhouse gases, water vapor, and ozone. In general, the concentration of any tracers within the ABL varies due to the changes in the mixing volume (i.e. ABL depth). In this study, we investigate the impact on the near-surface aerosol concentration in a valley site of 1) the boundary layer dilution due to vertical mixing and 2) changes in the wind patterns. We use a data set obtained during a 10-day field campaign in which a number of remote sensing and in-situ instruments were deployed, including a ground-based aerosol lidar system for monitoring of the ABL top height (zi), a particle counter to determine the number concentration of aerosol particles at eight different size ranges, and tower-based standard meteorological instruments. Results show a clearly visible decreasing trend of the mean daytime zi from 2900 m AGL (above ground level) to 2200 m AGL during a three-day period which resulted in increased near-surface pollutant concentrations. An inverse relationship exists between the zi and the fine fraction (0.3-0.7 μm) accumulation mode particles (AMP) on some days due to the dilution effect in a well-mixed ABL. These days are characterized by the absence of daytime upvalley winds and the presence of northwesterly synoptic-driven winds. In contrast, on the days with an onset of an upvalley wind circulation after the morning transition, the wind-driven local transport mechanism outweighs the ABL-dilution effect in determining the variability of AMP concentration. The interplay between the ABL depth evolution and the onset of the upvalley wind during the morning transition period significantly governs the air quality in a valley and could be an important component in the studies of mountain meteorology and air quality. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Seasonal and diurnal variability of essential oil and its components in Origanum onites L. grown in the ecological conditions of Çukurova

    Directory of Open Access Journals (Sweden)

    Kirpik, Muzaffer

    2005-12-01

    Full Text Available Turkish Oregano ( Origanum onites L. is one of the most commonly collected from nature as well as cultivated Origanum species in Turkey . In addition, Turkish Oregano is the most exported Origanum species from Turkey to the entire World. In this study, the seasonal and diurnal variability of the essential oil content in Origanum onites L. grown in the ecological conditions of Çukurova was studied from September 2000-August 2001. Monthly variability of the essential oil composition was also studied. The plant cuttings collected from the region were rooted in the greenhouse and transferred to the field in a split plot design with three replications. One year later from transplanting, fresh leaves from the top shoots were collected every week three times a day on Monday (at 08.00, 12.00 and 16.00 o'clock throughout the year. The content and composition of the essential oil were analysed in fresh leaf samples by hydrodistillation. The essential oil content changed according to the seasons and the hour of day. The highest essential oil content (% 1.92 was found in the post-flowering -at the beginning of the seed formation period in the afternoon harvests during the second half of June (40th week. The essential oil composition varied monthly and the highest value (% 73.65 of carvacrol, the main component of the essential oil, was obtained from the flowering period in MayEl orégano turco ( Origanum onites L. es uno de los más recolectados de la naturaleza así como la especie de orégano más cultivada en Turquía. Además es la especie de orégano más exportada desde Turquía a todo el mundo. En este trabajo se estudió la variabilidad estacional y diurna del contenido de aceite esencial de Origanum onites L. cultivado en las condiciones ecológicas de Çukurova desde Septiembre de 2000 a Agosto de 2001. Se estudió también la variabilidad mensual de la composición del aceite esencial. Los plantones recogidos en la región fueron plantados en un

  17. Photometric and polarimetric variability and mass-loss rate of the massive binary Wolf-Rayet star HDE 311884 (WN6 + 05: V)

    International Nuclear Information System (INIS)

    Moffat, A.F.J.; Drissen, L.; Robert, C.; Lamontagne, R.; Coziol, R.

    1990-01-01

    Photometric and polarimetric monitoring of the Wolf-Rayet (W-R) + O-type binary system HDE 311884 = WR 47 over many orbital cycles shows the clear effects of phase-dependent electron scattering of O-star light as the orbiting O companion shines through varying column density of W-R stellar wind material. In contrast to this wind-type eclipse, the stars themselves do not quite eclipse. Both photometry and polarimetry give a consistent estimate of the mass-loss rate of the W-R component: at about 0.00003 solar mass/yr. The orbital inclination, i = 70 deg, along with the previously published velocity orbit, yields high masses: M(WN6) = 48 solar masses and M(O5:V) = 57 solar masses. 33 refs

  18. THE ALHAMBRA PHOTOMETRIC SYSTEM

    International Nuclear Information System (INIS)

    Villegas, T. Aparicio; Alfaro, E. J.; Cabrera-Cano, J.

    2010-01-01

    This paper presents the characterization of the optical range of the ALHAMBRA photometric system, a 20 contiguous, equal-width, medium-band CCD system with wavelength coverage from 3500 A to 9700 A. The photometric description of the system is done by presenting the full response curve as a product of the filters, CCD, and atmospheric transmission curves, and using some first- and second-order moments of this response function. We also introduce the set of standard stars that defines the system, formed by 31 classic spectrophotometric standard stars which have been used in the calibration of other known photometric systems, and 288 stars, flux calibrated homogeneously, from the Next Generation Spectral Library (NGSL). Based on the NGSL, we determine the transformation equations between Sloan Digital Sky Survey ugriz photometry and the ALHAMBRA photometric system, in order to establish some relations between both systems. Finally, we develop and discuss a strategy to calculate the photometric zero points of the different pointings in the ALHAMBRA project.

  19. Photometric Lunar Surface Reconstruction

    Science.gov (United States)

    Nefian, Ara V.; Alexandrov, Oleg; Morattlo, Zachary; Kim, Taemin; Beyer, Ross A.

    2013-01-01

    Accurate photometric reconstruction of the Lunar surface is important in the context of upcoming NASA robotic missions to the Moon and in giving a more accurate understanding of the Lunar soil composition. This paper describes a novel approach for joint estimation of Lunar albedo, camera exposure time, and photometric parameters that utilizes an accurate Lunar-Lambertian reflectance model and previously derived Lunar topography of the area visualized during the Apollo missions. The method introduced here is used in creating the largest Lunar albedo map (16% of the Lunar surface) at the resolution of 10 meters/pixel.

  20. Summer to Winter Diurnal Variabilities of Temperature and Water Vapour in the Lowermost Troposphere as Observed by HAMSTRAD over Dome C, Antarctica

    Science.gov (United States)

    Ricaud, P.; Genthon, C.; Durand, P.; Attié, J.-L.; Carminati, F.; Canut, G.; Vanacker, J.-F.; Moggio, L.; Courcoux, Y.; Pellegrini, A.; Rose, T.

    2012-04-01

    The HAMSTRAD (H2O Antarctica Microwave Stratospheric and Tropospheric Radiometers) microwave radiometer operating at 60 GHz (oxygen line, thus temperature) and 183 GHz (water vapour line) has been permanently deployed at the Dome C station, Concordia, Antarctica [75°06'S, 123°21'E, 3,233 m above mean sea level] in January 2010 to study long-term trends in tropospheric absolute humidity and temperature. The great sensitivity of the instrument in the lowermost troposphere helped to characterize the diurnal cycle of temperature and H2O from the austral summer (January 2010) to the winter (June 2010) seasons from heights of 10 to 200 m in the planetary boundary layer (PBL). The study has characterized the vertical resolution of the HAMSTRAD measurements: 10-20 m for temperature and 25-50 m for H2O. A strong diurnal cycle in temperature and H2O (although noisier) has been measured in summertime at 10 m, decreasing in amplitude with height, and phase-shifted by about 4 h above 50 m with a strong H2O-temperature correlation (>0.8) throughout the entire PBL. In autumn, whilst the diurnal cycle in temperature and H2O is less intense, a 12-h phase shift is observed above 30 m. In wintertime, a weak diurnal signal measured between 10 to 200 m is attributed to the methodology employed, which consists of monthly averaged data, and that combines air masses from different origins (sampling effect) and not to the imprint of the null solar irradiation. In situ sensors scanning the entire 24-h period, radiosondes launched at 2000 local solar time (LST) and European Centre for Medium-Range Weather Forecasts (ECMWF) analyses at 0200, 0800, 1400 and 2000 LST agree very well with the HAMSTRAD diurnal cycles for temperature and relatively well for absolute humidity. For temperature, HAMSTRAD tends to be consistent with all the other datasets but shows a smoother vertical profile from 10 to 100 m compared to radiosondes and in-situ data, with ECMWF profiles even smoother than HAMSTRAD

  1. Astrometric vs. photometric microlensing

    NARCIS (Netherlands)

    Dominik, M; Brainerd, TG; Kochanek, CS

    2001-01-01

    I discuss the differences between the properties of astrometric and photometric microlensing and between the arising prospects for survey and follow-up experiments based on these two different signatures. In particular, the prospects for binary stars and extra-solar planets are considered.

  2. Photometric microdetermination of malathion

    Science.gov (United States)

    Kallman, B.J.

    1962-01-01

    Carboxylic esters and lactones react with alkaline hydroxylamine to yield hydroxamates; these in acidic solution form colored iron(III) complexes. A photometric determination of such esters and lactones is thus permitted and has been extensively applied ( I-6). Hestrin ( 3) utilized this method for the microdetermination of acetylcholine and his procedure is much used for the in vitro study of cholinesterase activity and inhibition (4-6).

  3. Multiview photometric stereo.

    Science.gov (United States)

    Hernández Esteban, Carlos; Vogiatzis, George; Cipolla, Roberto

    2008-03-01

    This paper addresses the problem of obtaining complete, detailed reconstructions of textureless shiny objects. We present an algorithm which uses silhouettes of the object, as well as images obtained under changing illumination conditions. In contrast with previous photometric stereo techniques, ours is not limited to a single viewpoint but produces accurate reconstructions in full 3D. A number of images of the object are obtained from multiple viewpoints, under varying lighting conditions. Starting from the silhouettes, the algorithm recovers camera motion and constructs the object's visual hull. This is then used to recover the illumination and initialise a multi-view photometric stereo scheme to obtain a closed surface reconstruction. There are two main contributions in this paper: Firstly we describe a robust technique to estimate light directions and intensities and secondly, we introduce a novel formulation of photometric stereo which combines multiple viewpoints and hence allows closed surface reconstructions. The algorithm has been implemented as a practical model acquisition system. Here, a quantitative evaluation of the algorithm on synthetic data is presented together with complete reconstructions of challenging real objects. Finally, we show experimentally how even in the case of highly textured objects, this technique can greatly improve on correspondence-based multi-view stereo results.

  4. New Variable Stars Discovered by Data Mining Images Taken during Recent Asteroid Photometric Observations. II. Results from July 2015 through December 2016

    Science.gov (United States)

    Papini, R.; Marchini, A.; Salvaggio, F.; Agnetti, D.; Bacci, P.; Banfi, M.; Bianciardi, G.; Collina, M.; Franco, L.; Galli, G.; Milani, M. G. A.; Lopresti, C.; Marino, G.; Rizzuti, L.; Ruocco, N.; Quadri, U.

    2017-12-01

    This paper follows the previous publication of new variables discovered at Astronomical Observatory, DSFTA, University of Siena, while observing asteroids in order to determine their rotational periods. Usually, this task requires time series images acquisition on a single field for as long as possible on a few nights not necessarily consecutive. Checking continually this "goldmine" allowed us to discover 57 variable stars not yet listed in catalogues or databases. While most of the new variables are eclipsing binaries, a few belong to the RR Lyrae or delta Scuti class. Since asteroid work is definitely a time-consuming activity, coordinated campaigns of follow-up with other observatories have been fundamental in order to determine the elements of the ephemeris and sometimes the right subclass of variability. Further observations of these new variables are therefore strongly encouraged in order to better characterize these stars, especially pulsating ones whose data combined with those taken during professional surveys seem to suggest the presence of light curve amplitude and period variations.

  5. Photometric properties of Mars soils analogs

    Science.gov (United States)

    Pommerol, A.; Thomas, N.; Jost, B.; Beck, P.; Okubo, C.; McEwen, A.S.

    2013-01-01

    We have measured the bidirectional reflectance of analogs of dry, wet, and frozen Martian soils over a wide range of phase angles in the visible spectral range. All samples were produced from two geologic samples: the standard JSC Mars-1 soil simulant and Hawaiian basaltic sand. In a first step, experiments were conducted with the dry samples to investigate the effects of surface texture. Comparisons with results independently obtained by different teams with similar samples showed a satisfying reproducibility of the photometric measurements as well as a noticeable influence of surface textures resulting from different sample preparation procedures. In a second step, water was introduced to produce wet and frozen samples and their photometry investigated. Optical microscope images of the samples provided information about their microtexture. Liquid water, even in relatively low amount, resulted in the disappearance of the backscattering peak and the appearance of a forward-scattering peak whose intensity increases with the amount of water. Specular reflections only appeared when water was present in an amount large enough to allow water to form a film at the surface of the sample. Icy samples showed a wide variability of photometric properties depending on the physical properties of the water ice. We discuss the implications of these measurements in terms of the expected photometric behavior of the Martian surface, from equatorial to circum-polar regions. In particular, we propose some simple photometric criteria to improve the identification of wet and/or icy soils from multiple observations under different geometries.

  6. The field high-amplitude SX Phe variable BL Cam: results from a multisite photometric campaign. II. Evidence of a binary - possibly triple - system

    Czech Academy of Sciences Publication Activity Database

    Fauvaud, S.; Sareyan, J.P.; Ribas, I.; Rodriguez, E.; Lampens, P.; Klingenberg, G.; Farrell, J.A.; Fumagalli, F.; Simonetti, J.H.; Wolf, M.; Santacana, G.; Zhou, A.; Michel, R.; Fox-Machado, L.; Alvarez, M.; Nava-Vega, A.; Lopez-Gonzalez, M.J.; Casanova, V.M.; Aceituno, F.J.; Scheggia, I.; Rives, J.-J.; Hintz, E.G.; Van Cauteren, P.; Helvaci, M.; Yesilyaprak, C.; Graham, K.A.; Král, L.; Kocián, R.; Kučáková, Hana; Fauvaud, M.; Granslo, B.H.; Michelet, J.; Nicholson, M.P.; Vugnon, J.-M.; Kotková, Lenka; Truparova, K.; Ulusoy, G.; Yasarsoy, B.; Avdibegovic, A.; Blazek, M.; Kliner, J.; Zasche, P.; Bartosikova, S.; Vilasek, M.; Trondal, O.; Van Den Abbeel, F.; Behrend, R.; Wuecher, H.

    2010-01-01

    Roč. 515, June (2010), A39/1-A39/7 ISSN 0004-6361 Institutional research plan: CEZ:AV0Z10030501 Keywords : variables stars * BL Camelopardalis * oscillations Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.410, year: 2010

  7. Photometric investigation of the Herbig Ae/Be star MWC 297. I. Quasisimultaneous UBVRIJHK observations

    International Nuclear Information System (INIS)

    Bergner, Yu.K.; Kozlov, V.P.; Krivtsov, A.A.; Miroshnichenko, A.S.; Yudin, R.V.; Yutanov, N.Yu.; Dzhakusheva, K.G.; Kuratov, K.S.; Mukanov, D.B.

    1988-01-01

    In order to make a statistical investigation of the photometric variability of the young star MWC 297 a number of quasisimultaneous observations in the photometric bands UBVRIJHK has been made. The coefficients of the correlation between the variations of the brightness in the different photometric bands have been determined by the proposed method. An anticorrelation between the variations in the bands U and K has been found. A possible mechanisms of the irregular variability of the star is proposed

  8. Long-term photometric behaviour of outbursting AM CVn systems

    OpenAIRE

    Levitan, David; Groot, Paul J.; Prince, Thomas A.; Kulkarni, Shrinivas R.; Laher, Russ; Ofek, Eran O.; Sesar, Branimir; Surace, Jason

    2015-01-01

    The AM CVn systems are a class of He-rich, post-period minimum, semidetached, ultracompact binaries. Their long-term light curves have been poorly understood due to the few systems known and the long (hundreds of days) recurrence times between outbursts. We present combined photometric light curves from the Lincoln Near Earth Asteroid Research, Catalina Real-Time Transient Survey, and Palomar Transient Factory synoptic surveys to study the photometric variability of these systems over an almo...

  9. Improved boundary layer height measurement using a fuzzy logic method: Diurnal and seasonal variabilities of the convective boundary layer over a tropical station

    Science.gov (United States)

    Allabakash, S.; Yasodha, P.; Bianco, L.; Venkatramana Reddy, S.; Srinivasulu, P.; Lim, S.

    2017-09-01

    This paper presents the efficacy of a "tuned" fuzzy logic method at determining the height of the boundary layer using the measurements from a 1280 MHz lower atmospheric radar wind profiler located in Gadanki (13.5°N, 79°E, 375 mean sea level), India, and discusses the diurnal and seasonal variations of the measured convective boundary layer over this tropical station. The original fuzzy logic (FL) method estimates the height of the atmospheric boundary layer combining the information from the range-corrected signal-to-noise ratio, the Doppler spectral width of the vertical velocity, and the vertical velocity itself, measured by the radar, through a series of thresholds and rules, which did not prove to be optimal for our radar system and geographical location. For this reason the algorithm was tuned to perform better on our data set. Atmospheric boundary layer heights obtained by this tuned FL method, the original FL method, and by a "standard method" (that only uses the information from the range-corrected signal-to-noise ratio) are compared with those obtained from potential temperature profiles measured by collocated Global Positioning System Radio Sonde during years 2011 and 2013. The comparison shows that the tuned FL method is more accurate than the other methods. Maximum convective boundary layer heights are observed between 14:00 and 15:00 local time (LT = UTC + 5:30) for clear-sky days. These daily maxima are found to be lower during winter and postmonsoon seasons and higher during premonsoon and monsoon seasons, due to net surface radiation and convective processes over this region being more intense during premonsoon and monsoon seasons and less intense in winter and postmonsoon seasons.

  10. Supernova Photometric Lightcurve Classification

    Science.gov (United States)

    Zaidi, Tayeb; Narayan, Gautham

    2016-01-01

    This is a preliminary report on photometric supernova classification. We first explore the properties of supernova light curves, and attempt to restructure the unevenly sampled and sparse data from assorted datasets to allow for processing and classification. The data was primarily drawn from the Dark Energy Survey (DES) simulated data, created for the Supernova Photometric Classification Challenge. This poster shows a method for producing a non-parametric representation of the light curve data, and applying a Random Forest classifier algorithm to distinguish between supernovae types. We examine the impact of Principal Component Analysis to reduce the dimensionality of the dataset, for future classification work. The classification code will be used in a stage of the ANTARES pipeline, created for use on the Large Synoptic Survey Telescope alert data and other wide-field surveys. The final figure-of-merit for the DES data in the r band was 60% for binary classification (Type I vs II).Zaidi was supported by the NOAO/KPNO Research Experiences for Undergraduates (REU) Program which is funded by the National Science Foundation Research Experiences for Undergraduates Program (AST-1262829).

  11. Diurnal variations of Titan

    Science.gov (United States)

    Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Mueller-Wodarg, I. C. F.; Kasprzak, W. T.; Waite, J. H.

    2009-04-01

    We present our analysis of the diurnal variations of Titan's ionosphere (between 1,000 and 1,400 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from 8 close encounters of the Cassini spacecraft with Titan. Though there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ~700 cm-3 below ~1,300 km. Such a plateau is associated with the combination of distinct diurnal variations of light and heavy ions. Light ions (e.g. CH5+, HCNH+, C2H5+) show strong diurnal variation, with clear bite-outs in their nightside distributions. In contrast, heavy ions (e.g. c-C3H3+, C2H3CNH+, C6H7+) present modest diurnal variation, with significant densities observed on the nightside. We propose that the distinctions between light and heavy ions are associated with their different chemical loss pathways, with the former primarily through "fast" ion-neutral chemistry and the latter through "slow" electron dissociative recombination. The INMS data suggest day-to-night transport as an important source of ions on Titan's nightside, to be distinguished from the conventional scenario of auroral ionization by magnetospheric particles as the only ionizing source on the nightside. This is supported by the strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes. We construct a time-dependent ion chemistry model to investigate the effects of day-to-night transport on the ionospheric structures of Titan. The predicted diurnal variation has similar general characteristics to those observed, with some apparent discrepancies which could be reconciled by imposing fast horizontal thermal winds in Titan's upper atmosphere.

  12. Impact of resolving the diurnal cycle in an ocean-atmosphere GCM. Pt. 1: a diurnally forced OGCM

    Energy Technology Data Exchange (ETDEWEB)

    Bernie, D.J. [University of Reading, National Centre for Atmospheric Science - Climate, Department of Meteorology, Reading (United Kingdom); Laboratoire d' Oceanographie et du Climat, Experimentation et Approches Numeriques, IPSL, Paris (France); Met Office Hadley Centre, Exeter, EX1 3PB (United Kingdom); Guilyardi, E. [University of Reading, National Centre for Atmospheric Science - Climate, Department of Meteorology, Reading (United Kingdom); Laboratoire d' Oceanographie et du Climat, Experimentation et Approches Numeriques, IPSL, Paris (France); Madec, G. [Laboratoire d' Oceanographie et du Climat, Experimentation et Approches Numeriques, IPSL, Paris (France); Slingo, J.M.; Woolnough, S.J. [University of Reading, National Centre for Atmospheric Science - Climate, Department of Meteorology, Reading (United Kingdom)

    2007-11-15

    The diurnal cycle is a fundamental time scale in the climate system, at which the upper ocean and atmosphere are routinely observed to vary. Current climate models, however, are not configured to resolve the diurnal cycle in the upper ocean or the interaction of the ocean and atmosphere on these time scales. This study examines the diurnal cycle of the tropical upper ocean and its climate impacts. In the present paper, the first of two, a high vertical resolution ocean general circulation model (OGCM), with modified physics, is developed which is able to resolve the diurnal cycle of sea surface temperature (SST) and current variability in the upper ocean. It is then validated against a satellite derived parameterization of diurnal SST variability and in-situ current observations. The model is then used to assess rectification of the intraseasonal SST response to the Madden-Julian oscillation (MJO) by the diurnal cycle of SST. Across the equatorial Indo-Pacific it is found that the diurnal cycle increases the intraseasonal SST response to the MJO by around 20%. In the Pacific, the diurnal cycle also modifies the exchange of momentum between equatorially divergent Ekman currents and the meridionally convergent geostrophic currents beneath, resulting in a 10% increase in the strength of the Ekman cells and equatorial upwelling. How the thermodynamic and dynamical impacts of the diurnal cycle effect the mean state, and variability, of the climate system cannot be fully investigated in the constrained design of ocean-only experiments presented here. The second part of this study, published separately, addresses the climate impacts of the diurnal cycle in the coupled system by coupling the OGCM developed here to an atmosphere general circulation model. (orig.)

  13. Diurnal variability in riverine dissolved organic matter composition determined by in situ optical measurement in the San Joaquin River (California, USA)

    Science.gov (United States)

    Spencer, R.G.M.; Pellerin, B.A.; Bergamaschi, B.A.; Downing, B.D.; Kraus, T.E.C.; Smart, D.R.; Dahlgren, R.A.; Hernes, P.J.

    2007-01-01

    Dissolved organic matter (DOM) concentration and composition in riverine and stream systems are known to vary with hydrological and productivity cycles over the annual and interannual time scales. Rivers are commonly perceived as homogeneous with respect to DOM concentration and composition, particularly under steady flow conditions over short time periods. However, few studies have evaluated the impact of short term variability ( monitored and serves to increase our understanding of its processing and fundamental role in the aquatic environment. Copyright ?? 2007 John Wiley & Sons, Ltd.

  14. Photometric stereo endoscopy.

    Science.gov (United States)

    Parot, Vicente; Lim, Daryl; González, Germán; Traverso, Giovanni; Nishioka, Norman S; Vakoc, Benjamin J; Durr, Nicholas J

    2013-07-01

    While color video endoscopy has enabled wide-field examination of the gastrointestinal tract, it often misses or incorrectly classifies lesions. Many of these missed lesions exhibit characteristic three-dimensional surface topographies. An endoscopic system that adds topographical measurements to conventional color imagery could therefore increase lesion detection and improve classification accuracy. We introduce photometric stereo endoscopy (PSE), a technique which allows high spatial frequency components of surface topography to be acquired simultaneously with conventional two-dimensional color imagery. We implement this technique in an endoscopic form factor and demonstrate that it can acquire the topography of small features with complex geometries and heterogeneous optical properties. PSE imaging of ex vivo human gastrointestinal tissue shows that surface topography measurements enable differentiation of abnormal shapes from surrounding normal tissue. Together, these results confirm that the topographical measurements can be obtained with relatively simple hardware in an endoscopic form factor, and suggest the potential of PSE to improve lesion detection and classification in gastrointestinal imaging.

  15. Astronomical Research Institute Photometric Results

    Science.gov (United States)

    Linder, Tyler R.; Sampson, Ryan; Holmes, Robert

    2013-01-01

    The Astronomical Research Institute (ARI) conducts astrometric and photometric studies of asteroids with a concentration on near-Earth objects (NEOs). A 0.76-m autoscope was used for photometric studies of seven asteroids of which two were main-belt targets and five were NEOs, including one potentially hazardous asteroid (PHA). These objects are: 3122 Florence, 3960 Chaliubieju, 5143 Heracles, (6455) 1992 HE, (36284) 2000 DM8, (62128) 2000 SO1, and 2010 LF86.

  16. Probabilistic Photometric Redshifts in the Era of Petascale Astronomy

    Energy Technology Data Exchange (ETDEWEB)

    Carrasco Kind, Matias [Univ. of Illinois, Urbana-Champaign, IL (United States)

    2014-01-01

    With the growth of large photometric surveys, accurately estimating photometric redshifts, preferably as a probability density function (PDF), and fully understanding the implicit systematic uncertainties in this process has become increasingly important. These surveys are expected to obtain images of billions of distinct galaxies. As a result, storing and analyzing all of these photometric redshift PDFs will be non-trivial, and this challenge becomes even more severe if a survey plans to compute and store multiple different PDFs. In this thesis, we have developed an end-to-end framework that will compute accurate and robust photometric redshift PDFs for massive data sets by using two new, state-of-the-art machine learning techniques that are based on a random forest and a random atlas, respectively. By using data from several photometric surveys, we demonstrate the applicability of these new techniques, and we demonstrate that our new approach is among the best techniques currently available. We also show how different techniques can be combined by using novel Bayesian techniques to improve the photometric redshift precision to unprecedented levels while also presenting new approaches to better identify outliers. In addition, our framework provides supplementary information regarding the data being analyzed, including unbiased estimates of the accuracy of the technique without resorting to a validation data set, identification of poor photometric redshift areas within the parameter space occupied by the spectroscopic training data, and a quantification of the relative importance of the variables used during the estimation process. Furthermore, we present a new approach to represent and store photometric redshift PDFs by using a sparse representation with outstanding compression and reconstruction capabilities. We also demonstrate how this framework can also be directly incorporated into cosmological analyses. The new techniques presented in this thesis are crucial

  17. Diurnal changes in ocean color sensed in satellite imagery

    Science.gov (United States)

    Arnone, Robert; Vandermuelen, Ryan; Soto, Inia; Ladner, Sherwin; Ondrusek, Michael; Yang, Haoping

    2017-07-01

    Measurements of diurnal changes in ocean color in turbid coastal regions in the Gulf of Mexico were characterized using above water spectral radiometry from a National Aeronautics and Space Administration (aerosol robotic network-WaveCIS CSI-06) site that can provide 8 to 10 observations per day. Satellite capability to detect diurnal changes in ocean color was characterized using hourly overlapping afternoon orbits of the visual infrared imaging radiometer suite (VIIRS) Suomi National Polar-orbiting Partnership ocean color sensor and validated with in situ observations. The monthly cycle of diurnal changes was investigated for different water masses using VIIRS overlaps. Results showed the capability of satellite observations to monitor hourly color changes in coastal regions that can be impacted by vertical movement of optical layers, in response to tides, resuspension, and river plume dispersion. The spatial variability of VIIRS diurnal changes showed the occurrence and displacement of phytoplankton blooming and decaying processes. The diurnal change in ocean color was above 20%, which represents a 30% change in chlorophyll-a. Seasonal changes in diurnal ocean color for different water masses suggest differences in summer and winter responses to surface processes. The diurnal changes observed using satellite ocean color can be used to define the following: surface processes associated with biological activity, vertical changes in optical depth, and advection of water masses.

  18. Diurnal changes in flavonoids

    International Nuclear Information System (INIS)

    Veit, M.; Bilger, W.; Mühlbauer, T.; Brummet, W.; Winter, K.

    1996-01-01

    Field studies of a tropical tree, Anacardium excelsum, and a northern hemisphere high altitude fern, Cryptogramma crispa, revealed marked diurnal changes in soluble flavonoid content of leaves and fronds, respectively. The flavonoid content increased during the morning and decreased during the afternoon. In plants of C. crispa covered with UV-B absorbing filters, the flavonoid content remained at a constant level throughout the day/night cycle. Upon removal of UV-B absorbing filters (at night), the flavonoid content increased the next morning in a fashion similar to that observed in control plants maintained without filters. Decreases in photosystem II photochemical efficiency upon exposure of C. crispa to natural daylight were similar in plants previously covered with UV-B absorbing filters and in control plants, probably owing to the observed ability of plants to rapidly accumulate UV-B protective flavonoids. (author)

  19. Biophysical information in asymmetric and symmetric diurnal bidirectional canopy reflectance

    Science.gov (United States)

    Vanderbilt, Vern C.; Caldwell, William F.; Pettigrew, Rita E.; Ustin, Susan L.; Martens, Scott N.; Rousseau, Robert A.; Berger, Kevin M.; Ganapol, B. D.; Kasischke, Eric S.; Clark, Jenny A.

    1991-01-01

    The authors present a theory for partitioning the information content in diurnal bidirectional reflectance measurements in order to detect differences potentially related to biophysical variables. The theory, which divides the canopy reflectance into asymmetric and symmetric functions of solar azimuth angle, attributes asymmetric variation to diurnal changes in the canopy biphysical properties. The symmetric function is attributed to the effects of sunlight interacting with a hypothetical average canopy which would display the average diurnal properties of the actual canopy. The authors analyzed radiometer data collected diurnally in the Thematic Mapper wavelength bands from two walnut canopies that received differing irrigation treatments. The reflectance of the canopies varied with sun and view angles and across seven bands in the visible, near-infrared, and middle infrared wavelength regions. Although one of the canopies was permanently water stressed and the other was stressed in mid-afternoon each day, no water stress signature was unambiguously evident in the reflectance data.

  20. Photometric requirements for portable changeable message signs.

    Science.gov (United States)

    2001-09-01

    This project reviewed the performance of pchangeable message signs (PCMSs) and developed photometric standards to establish performance requirements. In addition, researchers developed photometric test methods and recommended them for use in evaluati...

  1. Planck 2013 results. VIII. HFI photometric calibration and mapmaking

    CERN Document Server

    Ade, P A R; Armitage-Caplan, C; Arnaud, M; Ashdown, M; Atrio-Barandela, F; Aumont, J; Baccigalupi, C; Banday, A J; Barreiro, R B; Battaner, E; Benabed, K; Benoît, A; Benoit-Lévy, A; Bernard, J -P; Bersanelli, M; Bertincourt, B; Bielewicz, P; Bobin, J; Bock, J J; Bond, J R; Borrill, J; Bouchet, F R; Boulanger, F; Bridges, M; Bucher, M; Burigana, C; Cardoso, J -F; Catalano, A; Challinor, A; Chamballu, A; Chary, R -R; Chen, X; Chiang, L -Y; Chiang, H C; Christensen, P R; Church, S; Clements, D L; Colombi, S; Colombo, L P L; Combet, C; Couchot, F; Coulais, A; Crill, B P; Curto, A; Cuttaia, F; Danese, L; Davies, R D; de Bernardis, P; de Rosa, A; de Zotti, G; Delabrouille, J; Delouis, J -M; Désert, F -X; Dickinson, C; Diego, J M; Dole, H; Donzelli, S; Doré, O; Douspis, M; Dupac, X; Efstathiou, G; Enßlin, T A; Eriksen, H K; Filliard, C; Finelli, F; Forni, O; Frailis, M; Franceschi, E; Galeotta, S; Ganga, K; Giard, M; Giardino, G; Giraud-Héraud, Y; González-Nuevo, J; Górski, K M; Gratton, S; Gregorio, A; Gruppuso, A; Hansen, F K; Hanson, D; Harrison, D; Helou, G; Henrot-Versillé, S; Hernández-Monteagudo, C; Herranz, D; Hildebrandt, S R; Hivon, E; Hobson, M; Holmes, W A; Hornstrup, A; Hovest, W; Huffenberger, K M; Jaffe, T R; Jaffe, A H; Jones, W C; Juvela, M; Keihänen, E; Keskitalo, R; Kisner, T S; Kneissl, R; Knoche, J; Knox, L; Kunz, M; Kurki-Suonio, H; Lagache, G; Lamarre, J -M; Lasenby, A; Laureijs, R J; Lawrence, C R; Jeune, M Le; Lellouch, E; Leonardi, R; Leroy, C; Lesgourgues, J; Liguori, M; Lilje, P B; Linden-Vørnle, M; López-Caniego, M; Lubin, P M; Macías-Pérez, J F; Maffei, B; Mandolesi, N; Maris, M; Marshall, D J; Martin, P G; Martínez-González, E; Masi, S; Matarrese, S; Matthai, F; Maurin, L; Mazzotta, P; McGehee, P; Meinhold, P R; Melchiorri, A; Mendes, L; Mennella, A; Migliaccio, M; Mitra, S; Miville-Deschênes, M -A; Moneti, A; Montier, L; Moreno, R; Morgante, G; Mortlock, D; Munshi, D; Murphy, J A; Naselsky, P; Nati, F; Natoli, P; Netterfield, C B; Nørgaard-Nielsen, H U; Noviello, F; Novikov, D; Novikov, I; Osborne, S; Oxborrow, C A; Paci, F; Pagano, L; Pajot, F; Paladini, R; Paoletti, D; Partridge, B; Pasian, F; Patanchon, G; Perdereau, O; Perotto, L; Perrotta, F; Piacentini, F; Piat, M; Pierpaoli, E; Pietrobon, D; Plaszczynski, S; Pointecouteau, E; Polenta, G; Ponthieu, N; Popa, L; Poutanen, T; Pratt, G W; Prézeau, G; Prunet, S; Puget, J -L; Rachen, J P; Reinecke, M; Remazeilles, M; Renault, C; Ricciardi, S; Riller, T; Ristorcelli, I; Rocha, G; Rosset, C; Roudier, G; Rusholme, B; Santos, D; Savini, G; Shellard, E P S; Spencer, L D; Starck, J -L; Stolyarov, V; Stompor, R; Sudiwala, R; Sunyaev, R; Sureau, F; Sutton, D; Suur-Uski, A -S; Sygnet, J -F; Tauber, J A; Tavagnacco, D; Techene, S; Terenzi, L; Tomasi, M; Tristram, M; Tucci, M; Umana, G; Valenziano, L; Valiviita, J; Van Tent, B; Vielva, P; Villa, F; Vittorio, N; Wade, L A; Wandelt, B D; Yvon, D; Zacchei, A; Zonca, A

    2014-01-01

    This paper describes the processing applied to the HFI cleaned time-ordered data to produce photometrically calibrated maps. HFI observes the sky over a broad range of frequencies, from 100 to 857 GHz. To get the best accuracy on the calibration on such a large range, two different photometric calibration schemes have to be used. The 545 and 857 \\GHz\\ data are calibrated using Uranus and Neptune flux density measurements, compared with models of their atmospheric emissions to calibrate the data. The lower frequencies (below 353 GHz) are calibrated using the cosmological microwave background dipole.One of the components of this anisotropy results from the orbital motion of the satellite in the Solar System, and is therefore time-variable. Photometric calibration is thus tightly linked to mapmaking, which also addresses low frequency noise removal. The 2013 released HFI data show some evidence for apparent gain variations of the HFI bolometers' detection chain. These variations were identified by comparing obse...

  2. PHOTOMETRIC REDSHIFTS OF SUBMILLIMETER GALAXIES

    International Nuclear Information System (INIS)

    Chakrabarti, Sukanya; Magnelli, Benjamin; Lutz, Dieter; Berta, Stefano; Popesso, Paola; McKee, Christopher F.; Pozzi, Francesca

    2013-01-01

    We use the photometric redshift method of Chakrabarti and McKee to infer photometric redshifts of submillimeter galaxies with far-IR (FIR) Herschel data obtained as part of the PACS Evolutionary Probe program. For the sample with spectroscopic redshifts, we demonstrate the validity of this method over a large range of redshifts (4 ∼> z ∼> 0.3) and luminosities, finding an average accuracy in (1 + z phot )/(1 + z spec ) of 10%. Thus, this method is more accurate than other FIR photometric redshift methods. This method is different from typical FIR photometric methods in deriving redshifts from the light-to-gas mass (L/M) ratio of infrared-bright galaxies inferred from the FIR spectral energy distribution, rather than dust temperatures. To assess the dependence of our photometric redshift method on the data in this sample, we contrast the average accuracy of our method when we use PACS data, versus SPIRE data, versus both PACS and SPIRE data. We also discuss potential selection effects that may affect the Herschel sample. Once the redshift is derived, we can determine physical properties of infrared-bright galaxies, including the temperature variation within the dust envelope, luminosity, mass, and surface density. We use data from the GOODS-S field to calculate the star formation rate density (SFRD) of submillimeter bright sources detected by AzTEC and PACS. The AzTEC-PACS sources, which have a threshold 850 μm flux ∼> 5 mJy, contribute 15% of the SFRD from all ultraluminous infrared galaxies (L IR ∼> 10 12 L ☉ ), and 3% of the total SFRD at z ∼ 2

  3. Radial velocity variations of photometrically quiet, chromospherically inactive Kepler stars: A link between RV jitter and photometric flicker

    Energy Technology Data Exchange (ETDEWEB)

    Bastien, Fabienne A.; Stassun, Keivan G.; Pepper, Joshua [Physics and Astronomy Department, Vanderbilt University, 1807 Station B, Nashville, TN 37235 (United States); Wright, Jason T. [Center for Exoplanets and Habitable Worlds, 525 Davey Laboratory, The Pennsylvania State University, University Park, PA 16803 (United States); Aigrain, Suzanne [Sub-department of Astrophysics, Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom); Basri, Gibor [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Johnson, John A. [Department of Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Howard, Andrew W. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Walkowicz, Lucianne M. [Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08544 (United States)

    2014-02-01

    We compare stellar photometric variability, as measured from Kepler light curves by Basri et al., with measurements of radial velocity (RV) rms variations of all California Planet Search overlap stars. We newly derive rotation periods from the Kepler light curves for all of the stars in our study sample. The RV variations reported herein range from less than 4 to 135 m s{sup –1}, yet the stars all have amplitudes of photometric variability less than 3 mmag, reflecting the preference of the RV program for chromospherically 'quiet' stars. Despite the small size of our sample, we find with high statistical significance that the RV rms manifests strongly in the Fourier power spectrum of the light curve: stars that are noisier in RV have a greater number of frequency components in the light curve. We also find that spot models of the observed light curves systematically underpredict the observed RV variations by factors of ∼2-1000, likely because the low-level photometric variations in our sample are driven by processes not included in simple spot models. The stars best fit by these models tend to have simpler light curves, dominated by a single relatively high-amplitude component of variability. Finally, we demonstrate that the RV rms behavior of our sample can be explained in the context of the photometric variability evolutionary diagram introduced by Bastien et al. We use this diagram to derive the surface gravities of the stars in our sample, revealing many of them to have moved off the main sequence. More generally, we find that the stars with the largest RV rms are those that have evolved onto the 'flicker floor' sequence in that diagram, characterized by relatively low amplitude but highly complex photometric variations which grow as the stars evolve to become subgiants.

  4. Photometric Orbit of TX UMa

    Directory of Open Access Journals (Sweden)

    Kyu-Dong Oh

    1986-06-01

    Full Text Available Two-color photometric light curves (Oh and Chan 1984 of the eclipsing binary TX UMa have been analyzed by the method of differential corrections of the model of Wilson and Devinney(1971. The system found to be simi-detached with cooler and less massive component filling its Roche lobe. The absolute dimensions have been derived from the results of the photometric solutions with spectroscopic elements of Hiltner(1945. It is assumed that the B8V primary component is on the zero age main sequence stage of the core hydrogen burning and the secondary os at the core contraction stage after the shell hydrogen burning stage according to the Iben's (1967 evolutional tracks for 3.0m_solar and 1.0m_solar.

  5. Photometric device using optical fibers

    International Nuclear Information System (INIS)

    Boisde, Gilbert; Perez, J.-J.

    1981-02-01

    Remote measurements in radioactive environment are now possible with optical fibers. Measurement instruments developed by CEA are constitued of: - an optical probe (5 mm to 1 meter optical path length), - a photometric measurement device, - optical fiber links. 'TELEPHOT' is a photometric device for industrial installations. It is uses interferentiel filters for 2 to 5 simultaneous wave lengths. 'CRUDMETER' measures the muddiness of water. It can be equipped with a high sensitivity cell of 50 cm optical path length tested up to 250 bars. Coupling a double beam spectrophotometer to a remote optical probe, up to 1 meter optical path length, is carried out by means of an optical device using optical fibers links, eventually several hundred meter long. For these equipments special step index large core fibers, 1 to 1.5 mm in diameter, have been developed as well connectors. For industrial control and research these instruments offer new prospect thanks to optical fibers use [fr

  6. ACS Photometric Zero Point Verification

    Science.gov (United States)

    Dolphin, Andrew

    2003-07-01

    The uncertainties in the photometric zero points create a fundamental limit to the accuracy of photometry. The current state of the ACS calibration is surprisingly poor, with zero point uncertainties of 0.03 magnitudes in the Johnson filters. The reason for this is that ACS observations of excellent ground-based standard fields, such as the omega Cen field used for WFPC2 calibrations, have not been obtained. Instead, the ACS photometric calibrations are based primarily on semi-emprical synthetic zero points and observations of fields too crowded for accurate ground-based photometry. I propose to remedy this problem by obtaining ACS broadband images of the omega Cen standard field with both the WFC and HRC. This will permit the direct determination of the ACS transformations, and is expected to double the accuracy to which the ACS zero points are known. A second benefit is that it will facilitate the comparison of the WFPC2 and ACS photometric systems, which will be important as WFPC2 is phased out and ACS becomes HST's primary imager.

  7. Impact of resolving the diurnal cycle in an ocean-atmosphere GCM. Pt. 2. A diurnally coupled CGCM

    Energy Technology Data Exchange (ETDEWEB)

    Bernie, D.J. [Met Office Hadley Centre, Exeter (United Kingdom); University of Reading, National Centre for Atmospheric Science-Climate, Department of Meteorology, Reading (United Kingdom); Numeriques, IPSL, Laboratoire d' Oceanographie et du Climat, Experimentation et Approches, Paris (France); Guilyardi, E. [University of Reading, National Centre for Atmospheric Science-Climate, Department of Meteorology, Reading (United Kingdom); Numeriques, IPSL, Laboratoire d' Oceanographie et du Climat, Experimentation et Approches, Paris (France); Madec, G. [Numeriques, IPSL, Laboratoire d' Oceanographie et du Climat, Experimentation et Approches, Paris (France); Slingo, J.M.; Woolnough, S.J.; Cole, J. [University of Reading, National Centre for Atmospheric Science-Climate, Department of Meteorology, Reading (United Kingdom)

    2008-12-15

    Coupled ocean atmosphere general circulation models (GCM) are typically coupled once every 24 h, excluding the diurnal cycle from the upper ocean. Previous studies attempting to examine the role of the diurnal cycle of the upper ocean and particularly of diurnal SST variability have used models unable to resolve the processes of interest. In part 1 of this study a high vertical resolution ocean GCM configuration with modified physics was developed that could resolve the diurnal cycle in the upper ocean. In this study it is coupled every 3 h to atmospheric GCM to examine the sensitivity of the mean climate simulation and aspects of its variability to the inclusion of diurnal ocean-atmosphere coupling. The inclusion of the diurnal cycle leads to a tropics wide increase in mean sea surface temperature (SST), with the strongest signal being across the equatorial Pacific where the warming increases from 0.2 C in the central and western Pacific to over 0.3 C in the eastern equatorial Pacific. Much of this warming is shown to be a direct consequence of the rectification of daily mean SST by the diurnal variability of SST. The warming of the equatorial Pacific leads to a redistribution of precipitation from the Inter tropical convergence zone (ITCZ) toward the equator. In the western Pacific there is an increase in precipitation between Papa new guinea and 170 E of up to 1.2 mm/day, improving the simulation compared to climatology. Pacific sub tropical cells are increased in strength by about 10%, in line with results of part 1 of this study, due to the modification of the exchange of momentum between the equatorially divergent Ekman currents and the geostropic convergence at depth, effectively increasing the dynamical response of the tropical Pacific to zonal wind stresses. During the spring relaxation of the Pacific trade winds, a large diurnal cycle of SST increases the seasonal warming of the equatorial Pacific. When the trade winds then re-intensify, the increase in

  8. Calibrating photometric redshifts of luminous red galaxies

    International Nuclear Information System (INIS)

    Padmanabhan, Nikhil; Budavari, Tamas; Schlegel, David J.; Bridges, Terry; Brinkmann, Jonathan

    2005-01-01

    We discuss the construction of a photometric redshift catalogue of luminous red galaxies (LRGs) from the Sloan Digital Sky Survey (SDSS), emphasizing the principal steps necessary for constructing such a catalogue: (i) photometrically selecting the sample, (ii) measuring photometric redshifts and their error distributions, and (iii) estimating the true redshift distribution. We compare two photometric redshift algorithms for these data and find that they give comparable results. Calibrating against the SDSS and SDSS–2dF (Two Degree Field) spectroscopic surveys, we find that the photometric redshift accuracy is σ~ 0.03 for redshifts less than 0.55 and worsens at higher redshift (~ 0.06 for z < 0.7). These errors are caused by photometric scatter, as well as systematic errors in the templates, filter curves and photometric zero-points. We also parametrize the photometric redshift error distribution with a sum of Gaussians and use this model to deconvolve the errors from the measured photometric redshift distribution to estimate the true redshift distribution. We pay special attention to the stability of this deconvolution, regularizing the method with a prior on the smoothness of the true redshift distribution. The methods that we develop are applicable to general photometric redshift surveys.

  9. Photometric monitoring of pre-main sequence stars - 2

    International Nuclear Information System (INIS)

    Evans, A.; Davies, J.K.; Kilkenny, D.; Bode, M.F.

    1989-01-01

    A discussion is presented of the infrared and optical photometric variability of the pre-main sequence stars BF Ori and UX Ori. In the former case, the reddening that occurs during decline, at both optical and infrared wavelengths, is consistent with variable extinction by circumstellar grains having an interstellar-like reddening law. While in the case of UX Ori, the data suggest variability due to starspots. In both cases, a study of the polarimetric variability would be valuable to confirm these conclusions. (author)

  10. Revised photometric elements of XZ And

    International Nuclear Information System (INIS)

    Giuricin, G.; Mardirossian, F.; Predolin, F.

    1980-01-01

    With the aid of Wood's (1972) computer program we have reanalyzed the photoelectric lightcurves of XZ And, made by Blitzstein (1954) and by Reinhardt (1967), from which appreciably different sets of photometric elements have previously been deduced. The photometric elements that we have derived separately from different lightcurves turned out to be in good agreement. Thus XZ And, whose seondary - somewhat larger than its hotter companion - appears to be roughly a G5-type star, has well-determined photometric elements. (author)

  11. A photometric study of Enceladus

    Science.gov (United States)

    Verbiscer, Anne J.; Veverka, Joseph

    1994-01-01

    We have supplemented Voyager imaging data from Enceladus (limited to phase angles of 13 deg-43 deg) with recent Earth-based CCD observations to obtain an improved determination of the Bond albedo, to construct an albedo map of the satellite, and to constrain parameters in Hapke's (1986) photometric equation. A major result is evidence of regional variations in the physical properties of Enceladus' surface. The average global photometric properties are described by single scattering albedo omega(sub 0) average = 0.998 +/- 0.001, macroscopic roughness parameter theta average = 6 +/- 1 deg, and Henyey-Greenstein asymmetry parameter g = -0.399 +/- 0.005. The value of theta average is smaller than the 14 deg found by fitting whole-disk data, which include all terrains on Enceladus. The opposition surge amplitude B(sub 0) = 0.21 +/- 0.07 and regolith compaction parameter h = 0.014 +/- 0.02 are loosely constrained by the scarcity of and uncertainty in near-opposition observations. From the solar phase curve we determine the geometric albedo of Enceladus p(sub v) = 0.99 +/- 0.06 and phase integral q = 0.92 +/- 0.05, which corresponds to a spherical albedo A = p(sub v)q = 0.91 +/- 0.1. Since the spectrum of Enceladus is fairly flat, we can approximate the Bond albedo A(sub B) with the spherical albedo. Our photometric analysis is summarized in terms of an albedo map which generally reproduces the satellite's observed lightcurve and indicates that normal reflectances range from 0.9 on the leading hemisphere to 1.4 on the trailing one. The albedo map also revels an albedo variation of 15% from longitudes 170 deg to 200 deg, corresponding to the boundary between the leading and trailing hemispheres.

  12. Sloan Digital Sky Survey Photometric Calibration Revisited

    International Nuclear Information System (INIS)

    Marriner, John

    2012-01-01

    The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

  13. Sloan Digital Sky Survey Photometric Calibration Revisited

    Energy Technology Data Exchange (ETDEWEB)

    Marriner, John; /Fermilab

    2012-06-29

    The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

  14. Using a 1-D model to reproduce diurnal SST signals

    DEFF Research Database (Denmark)

    Karagali, Ioanna; Høyer, Jacob L.

    2014-01-01

    The diurnal variability of SST has been extensively studied as it poses challenges for validating and calibrating satellite sensors, merging SST time series, oceanic and atmospheric modelling. As heat is significantly trapped close to the surface, the diurnal signal’s maximum amplitude is best...... captured by radiometers. The availability of infra-red retrievals from a geostationary orbit allows the hourly monitoring of the diurnal SST evolution. When infra-red SSTs are validated with in situ measurements a general mismatch is found, associated with the different reference depth of each type...... of measurement. A generally preferred approach to bridge the gap between in situ and remotely obtained measurements is through modelling of the upper ocean temperature. This ESA supported study focuses on the implementation of the 1 dimensional General Ocean Turbulence Model (GOTM), in order to resolve...

  15. Diurnal tides in the Arctic Ocean

    Science.gov (United States)

    Kowalik, Z.; Proshutinsky, A. Y.

    1993-01-01

    A 2D numerical model with a space grid of about 14 km is applied to calculate diurnal tidal constituents K(1) and O(1) in the Arctic Ocean. Calculated corange and cotidal charts show that along the continental slope, local regions of increased sea level amplitude, highly variable phase and enhanced currents occur. It is shown that in these local regions, shelf waves (topographic waves) of tidal origin are generated. In the Arctic Ocean and Northern Atlantic Ocean more than 30 regions of enhanced currents are identified. To prove the near-resonant interaction of the diurnal tides with the local bottom topography, the natural periods of oscillations for all regions have been calculated. The flux of energy averaged over the tidal period depicts the gyres of semitrapped energy, suggesting that the shelf waves are partially trapped over the irregularities of the bottom topography. It is shown that the occurrence of near-resonance phenomenon changes the energy flow in the tidal waves. First, the flux of energy from the astronomical sources is amplified in the shelf wave regions, and afterwards the tidal energy is strongly dissipated in the same regions.

  16. Diurnal changes in ocean color in coastal waters

    Science.gov (United States)

    Arnone, Robert; Vandermeulen, Ryan; Ladner, Sherwin; Ondrusek, Michael; Kovach, Charles; Yang, Haoping; Salisbury, Joseph

    2016-05-01

    Coastal processes can change on hourly time scales in response to tides, winds and biological activity, which can influence the color of surface waters. These temporal and spatial ocean color changes require satellite validation for applications using bio-optical products to delineate diurnal processes. The diurnal color change and capability for satellite ocean color response were determined with in situ and satellite observations. Hourly variations in satellite ocean color are dependent on several properties which include: a) sensor characterization b) advection of water masses and c) diurnal response of biological and optical water properties. The in situ diurnal changes in ocean color in a dynamic turbid coastal region in the northern Gulf of Mexico were characterized using above water spectral radiometry from an AErosol RObotic NETwork (AERONET -WavCIS CSI-06) site that provides up to 8-10 observations per day (in 15-30 minute increments). These in situ diurnal changes were used to validate and quantify natural bio-optical fluctuations in satellite ocean color measurements. Satellite capability to detect changes in ocean color was characterized by using overlapping afternoon orbits of the VIIRS-NPP ocean color sensor within 100 minutes. Results show the capability of multiple satellite observations to monitor hourly color changes in dynamic coastal regions that are impacted by tides, re-suspension, and river plume dispersion. Hourly changes in satellite ocean color were validated with in situ observation on multiple occurrences during different times of the afternoon. Also, the spatial variability of VIIRS diurnal changes shows the occurrence and displacement of phytoplankton blooms and decay during the afternoon period. Results suggest that determining the temporal and spatial changes in a color / phytoplankton bloom from the morning to afternoon time period will require additional satellite coverage periods in the coastal zone.

  17. Individual Differences in Diurnal Preference and Time-of-Exercise Interact to Predict Exercise Frequency.

    Science.gov (United States)

    Hisler, Garrett C; Phillips, Alison L; Krizan, Zlatan

    2017-06-01

    Diurnal preference (and chronotype more generally) has been implicated in exercise behavior, but this relation has not been examined using objective exercise measurements nor have potential psychosocial mediators been examined. Furthermore, time-of-day often moderates diurnal preference's influence on outcomes, and it is unknown whether time-of-exercise may influence the relation between chronotype and exercise frequency. The current study examined whether individual differences in diurnal preference ("morningness-eveningness") predict unique variance in exercise frequency and if commonly studied psychosocial variables mediate this relation (i.e., behavioral intentions, internal exercise control, external exercise control, and conscientiousness). Moreover, the study sought to test whether individuals' typical time-of-exercise moderated the impact of diurnal preference on exercise frequency. One hundred twelve healthy adults (mean age = 25.4; SD = 11.6 years) completed baseline demographics and then wore Fitbit Zips® for 4 weeks to objectively measure exercise frequency and typical time-of-exercise. At the end of the study, participants also self-reported recent exercise. Diurnal preference predicted both self-reported exercise and Fitbit-recorded exercise frequency. When evaluating mediators, only conscientiousness emerged as a partial mediator of the relation between diurnal preference and self-reported exercise. In addition, time-of-exercise moderated diurnal preference's relation to both self-reported exercise and Fitbit-recorded exercise frequency such that diurnal preference predicted higher exercise frequency when exercise occurred at a time that was congruent with one's diurnal preference. Based on these findings, diurnal preference is valuable, above and beyond other psychological constructs, in predicting exercise frequency and represents an important variable to incorporate into interventions seeking to increase exercise.

  18. Photometric Studies of GEO Debris

    Science.gov (United States)

    Seitzer, Patrick; Cowardin, Heather M.; Barker, Edwin; Abercromby, Kira J.; Foreman, Gary; Horstman, Matt

    2009-01-01

    The photometric signature of a debris object can be useful in determining what the physical characteristics of a piece of debris are. We report on optical observations in multiple filters of debris at geosynchronous Earth orbit (GEO). Our sample is taken from GEO objects discovered in a survey with the University of Michigan's 0.6-m aperture Schmidt telescope MODEST (for Michigan Orbital DEbris Survey Telescope), and then followed up in real-time with the SMARTS (Small and Medium Aperture Research Telescope System) 0.9-m at CTIO for orbits and photometry. Our goal is to determine 6 parameter orbits and measure colors for all objects fainter than R = 15 th magnitude that are discovered in the MODEST survey. At this magnitude the distribution of observed angular rates changes significantly from that of brighter objects. There are two objectives: 1. Estimate the orbital distribution of objects selected on the basis of two observational criteria: brightness (magnitude) and angular rates. 2. Obtain magnitudes and colors in standard astronomical filters (BVRI) for comparison with reflectance spectra of likely spacecraft materials. What is the faint debris likely to be? In this paper we report on the photometric results. For a sample of 50 objects, more than 90 calibrated sequences of R-B-V-I-R magnitudes have been obtained with the CTIO 0.9-m. For objects that do not show large brightness variations, the colors are largely redder than solar in both B-R and R-I. The width of the color distribution may be intrinsic to the nature of the surfaces, but also could be that we are seeing irregularly shaped objects and measuring the colors at different times with just one telescope. For a smaller sample of objects we have observed with synchronized CCD cameras on the two telescopes. The CTIO 0.9-m observes in B, and MODEST in R. The CCD cameras are electronically linked together so that the start time and duration of observations are the same to better than 50 milliseconds. Thus

  19. Photometric functions for photoclinometry and other applications

    Science.gov (United States)

    McEwen, A.S.

    1991-01-01

    Least-squared fits to the brightness profiles across a disk or "limb darkening" described by Hapke's photometric function are found for the simpler Minnaert and lunar-Lambert functions. The simpler functions are needed to reduce the number of unknown parameters in photoclinometry, especially to distinguish the brightness variations of the surface materials from that due to the resolved topography. The limb darkening varies with the Hapke parameters for macroscopic roughness (??), the single-scattering albedo (w), and the asymmetry factor of the particle phase function (g). Both of the simpler functions generally provide good matches to the limb darkening described by Hapke's function, but the lunar-Lambert function is superior when viewing angles are high and when (??) is less than 30??. Although a nonunique solution for the Minnaert function at high phase angles has been described for smooth surfaces, the discrepancy decreases with increasing (??) and virtually disappears when (??) reaches 30?? to 40??. The variation in limb darkening with w and g, pronounced for smooth surfaces, is reduced or eliminated when the Hapke parameters are in the range typical of most planetary surfaces; this result simplifies the problem of photoclinometry across terrains with variable surface materials. The Minnaert or lunar-Lambert fits to published Hapke models will give photoclinometric solutions that are very similar (>1?? slope discrepancy) to the Hapke-function solutions for nearly all of the bodies and terrains thus far modeled by Hapke's function. ?? 1991.

  20. RSO Characterization with Photometric Data Using Machine Learning

    Science.gov (United States)

    2015-10-18

    RSO Characterization with Photometric Data Using Machine Learning Michael Howard Charles River Analytics, Inc. Bernie Klem SASSO, Inc. Joe...and its behavior. This paper explores object characterization methods using photometric data. An important property of RSO photometric signatures is... photometric signature include geometry, orientation, material characteristics and stability. For this reason, it should be possible to recover these

  1. Photometric normalization of LROC WAC images

    Science.gov (United States)

    Sato, H.; Denevi, B.; Robinson, M. S.; Hapke, B. W.; McEwen, A. S.; LROC Science Team

    2010-12-01

    variability of the regolith from region to region. As the fitting area increases, the accuracy of curve fitting decreases due to the larger variety of albedo, topography, and composition. Thus we have adopted an albedo-dependent photometric normalization routine. Phase curves are derived for discreet bins of preliminary normalized reflectance calculated from Clementine global mosaic in a fitting area that is composed of predominantly mare in Oceanus Procellarum. The global WAC mosaic was then corrected pixel-by-pixel according to its preliminary reflectance map with satisfactory results. We observed that the phase curves per normalized-reflectance bins become steeper as the reflectance value increases. Further filtering by using FeO, TiO2, or optical maturity [5] for parameter calculations may help elucidate the effects of surface composition and maturity on photometric properties of the surface. [1] Hapke, B.W. (1993) Theory of Reflectance and Emittance Spectroscopy, Cambridge Univ. Press. [2] Schoenberg (1925) Ada. Soc. Febb., vol. 50. [3] Hillier et al. (1999) Icarus 141, 205-225. [4] McEwen (1991) Icarus 92, 298-311. [5] Lucey et al. (2000) JGR, v105, no E8, p20377-20386.

  2. ASTEROID PHOTOMETRIC CATALOG V1.1

    Data.gov (United States)

    National Aeronautics and Space Administration — The Asteroid Photometric Catalog (3rd update), Lagerkvist, et.al., 1993 [LAGERKVISTETAL1993], is a compilation of all asteroid lightcurve photometry published up to...

  3. Satellite, climatological, and theoretical inputs for modeling of the diurnal cycle of fire emissions

    Science.gov (United States)

    Hyer, E. J.; Reid, J. S.; Schmidt, C. C.; Giglio, L.; Prins, E.

    2009-12-01

    The diurnal cycle of fire activity is crucial for accurate simulation of atmospheric effects of fire emissions, especially at finer spatial and temporal scales. Estimating diurnal variability in emissions is also a critical problem for construction of emissions estimates from multiple sensors with variable coverage patterns. An optimal diurnal emissions estimate will use as much information as possible from satellite fire observations, compensate known biases in those observations, and use detailed theoretical models of the diurnal cycle to fill in missing information. As part of ongoing improvements to the Fire Location and Monitoring of Burning Emissions (FLAMBE) fire monitoring system, we evaluated several different methods of integrating observations with different temporal sampling. We used geostationary fire detections from WF_ABBA, fire detection data from MODIS, empirical diurnal cycles from TRMM, and simple theoretical diurnal curves based on surface heating. Our experiments integrated these data in different combinations to estimate the diurnal cycles of emissions for each location and time. Hourly emissions estimates derived using these methods were tested using an aerosol transport model. We present results of this comparison, and discuss the implications of our results for the broader problem of multi-sensor data fusion in fire emissions modeling.

  4. Photometric Study of Uranian Satellites

    Science.gov (United States)

    Kesten, Philip R.

    1998-01-01

    The best summary of my work at NASA is expressed in the following abstract, submitted the Division for Planetary Science of the American Astronomical Society and to be presented at the annual meeting in Madison in October. We report photometric measurements of Uranian satellites Miranda, Ariel, Umbriel and Titania (10.4 Aug. 1995), and Neptune's satellite Triton (21.2 Sept. 1995) with the infrared camera (IRCAM) and standard J (1.13 - 1.42 microns), H (1.53 - 1.81 microns), and K (2.00 - 2.41 microns) filters at the 3.8-m UKIRT telescope on Mauna Kea. The individual images frames are 256 x 256 pixels with a platescale of .286 arcsec/pixel, resulting in a 1.22 arc min field of view. This summer brought the IR photometry measurements nearly to a close. As indicated by the abstract above, I will present this work at the annual DPS meeting in October. In anticipation of the opening of the new Carl Sagan Laboratory for Cosmochemisty, of which I will be a participating member, I also devoted a considerable fraction of the summer to learning the biochemistry which underlies the experiments to be conducted. To put the end of the summary close to the beginning, it was a most productive summer.

  5. Photometric properties of Triton hazes

    Science.gov (United States)

    Hillier, J.; Veverka, J.

    1994-01-01

    Voyager imaging observations of Triton have been used to investigate the characteristics of the atmospheric hazes on Triton at three wavelengths: violet (0.41 micrometers), blue (0.48 micrometers), and green (0.56 micrometers). The globally averaged optical depth is wavelength dependent, varying from 0.034 in green to 0.063 in violet. These photometric results are dominated by the properties of localized discrete clouds rather than by those of the thinner, more widespread haze known to occur on Triton. The cloud particles are bright, with single-scattering albedos near unity at all three wavelengths, suggestive of a transparent icy condensate. The asymmetry parameter (+0.6) and the wavelength dependence of the optical depth both indicate cloud particles 0.2-0.4 micrometers in radius. The clouds are concentrated at 50-60 deg S latitude, where opacities up to three times the global average are observed. This is the same latitude region where most of the evidence for current surface activity is found, suggesting that the clouds may be related to the plumes or at least to some process connected with the sublimation of the south polar cap. The effects of possible temporal variations in the haze opacity are examined. Increases in the haze opacity tend to redden Triton. However, the degree of reddening is not sufficient to explain the full range of observed changed in Triton over the past decade; variations in the surface properties appear to be necessary.

  6. Photometrical Observations "SBIRS GEO-2"

    Science.gov (United States)

    Sukhov, P. P.; Epishev, V. P.; Karpenko, G. F.; Sukhov, K. P.; Kudak, V. I.

    2015-08-01

    Photometrical observations GSS "SBIRS GEO 2" in B,V,R filters were carried near the equinoxes 2014-2015. Used velocity electrophotometer based on the FEU-79 in the pulse-counting mode. Received more than 25 light curves. From the known dimensions are defined; effective reflecting area - Sγλ, the spectral reflectance index - γλ, periods of light variation. Color-indices showed that in the reflected light flux from the GSS prevails "red" component. In the light curves are periodically dips and specular flash. This shows that GSS orbit is not in a static position specified triaxial orientation as in dynamic motion. Assumed following dynamics of the satellite "SBIRS GEO 2" in orbit. Helical scanning the Earth's surface visible infrared sensors satellite occurs with a period P1 = 15.66 sec. and swinging of the GSS about the direction of the motion vector of the satellite in an orbit with P2 = 62.64 sec., from the northern to the southern pole. Thus, during the period of swinging GSS going on 2 scan the visible part of the northern and southern hemispheres. In some dates observations dynamics work satellite in orbit changed.

  7. Measurement of the photometric characteristics of LEDs

    International Nuclear Information System (INIS)

    Nazarenko, L.A.; Zubkov, D.P.

    2015-01-01

    Proposed and implemented a method for measuring LEDs, which is based on self-calibration of the LED goniophotometer facility by using a trap-detector. Designed and manufactured automated goniophotometer, which provides a measurement of high power LEDs at a specified junction temperature. Designed and experimentally researched the photometer with a photometric sphere based diffuser, which meets all requirements of CIE for photometric measurements of LEDs

  8. Diurnal variations of Titan's ionosphere

    Science.gov (United States)

    Cui, J.; Galand, M.; Yelle, R. V.; Vuitton, V.; Wahlund, J.-E.; Lavvas, P. P.; Müller-Wodarg, I. C. F.; Cravens, T. E.; Kasprzak, W. T.; Waite, J. H.

    2009-06-01

    We present our analysis of the diurnal variations of Titan's ionosphere (between 1000 and 1300 km) based on a sample of Ion Neutral Mass Spectrometer (INMS) measurements in the Open Source Ion (OSI) mode obtained from eight close encounters of the Cassini spacecraft with Titan. Although there is an overall ion depletion well beyond the terminator, the ion content on Titan's nightside is still appreciable, with a density plateau of ˜700 cm-3 below ˜1300 km. Such a plateau is a combined result of significant depletion of light ions and modest depletion of heavy ones on Titan's nightside. We propose that the distinctions between the diurnal variations of light and heavy ions are associated with their different chemical loss pathways, with the former primarily through “fast” ion-neutral chemistry and the latter through “slow” electron dissociative recombination. The strong correlation between the observed night-to-day ion density ratios and the associated ion lifetimes suggests a scenario in which the ions created on Titan's dayside may survive well to the nightside. The observed asymmetry between the dawn and dusk ion density profiles also supports such an interpretation. We construct a time-dependent ion chemistry model to investigate the effect of ion survival associated with solid body rotation alone as well as superrotating horizontal winds. For long-lived ions, the predicted diurnal variations have similar general characteristics to those observed. However, for short-lived ions, the model densities on the nightside are significantly lower than the observed values. This implies that electron precipitation from Saturn's magnetosphere may be an additional and important contributor to the densities of the short-lived ions observed on Titan's nightside.

  9. The many flavours of photometric redshifts

    Science.gov (United States)

    Salvato, Mara; Ilbert, Olivier; Hoyle, Ben

    2018-06-01

    Since more than 70 years ago, the colours of galaxies derived from flux measurements at different wavelengths have been used to estimate their cosmological distances. Such distance measurements, called photometric redshifts, are necessary for many scientific projects, ranging from investigations of the formation and evolution of galaxies and active galactic nuclei to precision cosmology. The primary benefit of photometric redshifts is that distance estimates can be obtained relatively cheaply for all sources detected in photometric images. The drawback is that these cheap estimates have low precision compared with resource-expensive spectroscopic ones. The methodology for estimating redshifts has been through several revolutions in recent decades, triggered by increasingly stringent requirements on the photometric redshift accuracy. Here, we review the various techniques for obtaining photometric redshifts, from template-fitting to machine learning and hybrid schemes. We also describe state-of-the-art results on current extragalactic samples and explain how survey strategy choices affect redshift accuracy. We close with a description of the photometric redshift efforts planned for upcoming wide-field surveys, which will collect data on billions of galaxies, aiming to investigate, among other matters, the stellar mass assembly and the nature of dark energy.

  10. CALIBRATION OF THE MEARTH PHOTOMETRIC SYSTEM: OPTICAL MAGNITUDES AND PHOTOMETRIC METALLICITY ESTIMATES FOR 1802 NEARBY M-DWARFS

    International Nuclear Information System (INIS)

    Dittmann, Jason A.; Irwin, Jonathan M.; Charbonneau, David; Newton, Elisabeth R.

    2016-01-01

    The MEarth Project is a photometric survey systematically searching the smallest stars near the Sun for transiting rocky planets. Since 2008, MEarth has taken approximately two million images of 1844 stars suspected to be mid-to-late M dwarfs. We have augmented this survey by taking nightly exposures of photometric standard stars and have utilized this data to photometrically calibrate the MEarth system, identify photometric nights, and obtain an optical magnitude with 1.5% precision for each M dwarf system. Each optical magnitude is an average over many years of data, and therefore should be largely immune to stellar variability and flaring. We combine this with trigonometric distance measurements, spectroscopic metallicity measurements, and 2MASS infrared magnitude measurements in order to derive a color–magnitude–metallicity relation across the mid-to-late M dwarf spectral sequence that can reproduce spectroscopic metallicity determinations to a precision of 0.1 dex. We release optical magnitudes and metallicity estimates for 1567 M dwarfs, many of which did not have an accurate determination of either prior to this work. For an additional 277 stars without a trigonometric parallax, we provide an estimate of the distance, assuming solar neighborhood metallicity. We find that the median metallicity for a volume-limited sample of stars within 20 pc of the Sun is [Fe/H] = −0.03 ± 0.008, and that 29/565 of these stars have a metallicity of [Fe/H] = −0.5 or lower, similar to the low-metallicity distribution of nearby G dwarfs. When combined with the results of ongoing and future planet surveys targeting these objects, the metallicity estimates presented here will be important for assessing the significance of any putative planet–metallicity correlation

  11. CALIBRATION OF THE MEARTH PHOTOMETRIC SYSTEM: OPTICAL MAGNITUDES AND PHOTOMETRIC METALLICITY ESTIMATES FOR 1802 NEARBY M-DWARFS

    Energy Technology Data Exchange (ETDEWEB)

    Dittmann, Jason A.; Irwin, Jonathan M.; Charbonneau, David; Newton, Elisabeth R. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States)

    2016-02-20

    The MEarth Project is a photometric survey systematically searching the smallest stars near the Sun for transiting rocky planets. Since 2008, MEarth has taken approximately two million images of 1844 stars suspected to be mid-to-late M dwarfs. We have augmented this survey by taking nightly exposures of photometric standard stars and have utilized this data to photometrically calibrate the MEarth system, identify photometric nights, and obtain an optical magnitude with 1.5% precision for each M dwarf system. Each optical magnitude is an average over many years of data, and therefore should be largely immune to stellar variability and flaring. We combine this with trigonometric distance measurements, spectroscopic metallicity measurements, and 2MASS infrared magnitude measurements in order to derive a color–magnitude–metallicity relation across the mid-to-late M dwarf spectral sequence that can reproduce spectroscopic metallicity determinations to a precision of 0.1 dex. We release optical magnitudes and metallicity estimates for 1567 M dwarfs, many of which did not have an accurate determination of either prior to this work. For an additional 277 stars without a trigonometric parallax, we provide an estimate of the distance, assuming solar neighborhood metallicity. We find that the median metallicity for a volume-limited sample of stars within 20 pc of the Sun is [Fe/H] = −0.03 ± 0.008, and that 29/565 of these stars have a metallicity of [Fe/H] = −0.5 or lower, similar to the low-metallicity distribution of nearby G dwarfs. When combined with the results of ongoing and future planet surveys targeting these objects, the metallicity estimates presented here will be important for assessing the significance of any putative planet–metallicity correlation.

  12. Evaluation of the sensitivity of the Amazonian diurnal cycle to convective intensity in reanalyses

    Science.gov (United States)

    Itterly, Kyle F.; Taylor, Patrick C.

    2017-02-01

    Model parameterizations of tropical deep convection are unable to reproduce the observed diurnal and spatial variability of convection in the Amazon, which contributes to climatological biases in the water cycle and energy budget. Convective intensity regimes are defined using percentiles of daily minimum 3-hourly averaged outgoing longwave radiation (OLR) from Clouds and the Earth's Radiant Energy System (CERES). This study compares the observed spatial variability of convective diurnal cycle statistics for each regime to MERRA-2 and ERA-Interim (ERA) reanalysis data sets. Composite diurnal cycle statistics are computed for daytime hours (06:00-21:00 local time) in the wet season (December-January-February). MERRA-2 matches observations more closely than ERA for domain averaged composite diurnal statistics—specifically precipitation. However, ERA reproduces mesoscale features of OLR and precipitation phase associated with topography and the propagation of the coastal squall line. Both reanalysis models are shown to underestimate extreme convection.

  13. Three-dimensional stereo by photometric ratios

    International Nuclear Information System (INIS)

    Wolff, L.B.; Angelopoulou, E.

    1994-01-01

    We present a methodology for corresponding a dense set of points on an object surface from photometric values for three-dimensional stereo computation of depth. The methodology utilizes multiple stereo pairs of images, with each stereo pair being taken of the identical scene but under different illumination. With just two stereo pairs of images taken under two different illumination conditions, a stereo pair of ratio images can be produced, one for the ratio of left-hand images and one for the ratio of right-hand images. We demonstrate how the photometric ratios composing these images can be used for accurate correspondence of object points. Object points having the same photometric ratio with respect to two different illumination conditions constitute a well-defined equivalence class of physical constraints defined by local surface orientation relative to illumination conditions. We formally show that for diffuse reflection the photometric ratio is invariant to varying camera characteristics, surface albedo, and viewpoint and that therefore the same photometric ratio in both images of a stereo pair implies the same equivalence class of physical constraints. The correspondence of photometric ratios along epipolar lines in a stereo pair of images under different illumination conditions is a correspondence of equivalent physical constraints, and the determination of depth from stereo can be performed. Whereas illumination planning is required, our photometric-based stereo methodology does not require knowledge of illumination conditions in the actual computation of three-dimensional depth and is applicable to perspective views. This technique extends the stereo determination of three-dimensional depth to smooth featureless surfaces without the use of precisely calibrated lighting. We demonstrate experimental depth maps from a dense set of points on smooth objects of known ground-truth shape, determined to within 1% depth accuracy

  14. Long-term stability of diurnal salivary cortisol and alpha-amylase secretion patterns.

    Science.gov (United States)

    Skoluda, Nadine; La Marca, Roberto; Gollwitzer, Mario; Müller, Andreas; Limm, Heribert; Marten-Mittag, Birgitt; Gündel, Harald; Angerer, Peter; Nater, Urs M

    2017-06-01

    This study aimed to investigate long-term stability and variability of diurnal cortisol and alpha-amylase patterns. Diurnal cortisol and alpha-amylase secretion patterns were assessed on a single workday with three waves of measurement across a total time period of 24months in 189 participants. Separate hierarchical linear models were analyzed, with and without a number of potential predictor variables (age, BMI, smoking, chronic stress, stress reactivity). While low long-term stability was found in diurnal cortisol, the stability of diurnal alpha-amylase was moderate across the time period of 24months. Several predictor variables had a positive impact on diurnal cortisol and alpha-amylase secretion patterns averaged across waves. Our findings underpin the notion that long-term stability is not necessarily warranted in longitudinal studies. It is important to choose an appropriate study design when attempting to disentangle clinically and biologically relevant changes from naturally occurring variations in diurnal cortisol and alpha-amylase. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. The effect of photometric and geometric context on photometric and geometric lightness effects.

    Science.gov (United States)

    Lee, Thomas Y; Brainard, David H

    2014-01-24

    We measured the lightness of probe tabs embedded at different orientations in various contextual images presented on a computer-controlled stereo display. Two background context planes met along a horizontal roof-like ridge. Each plane was a graphic rendering of a set of achromatic surfaces with the simulated illumination for each plane controlled independently. Photometric context was varied by changing the difference in simulated illumination intensity between the two background planes. Geometric context was varied by changing the angle between them. We parsed the data into separate photometric effects and geometric effects. For fixed geometry, varying photometric context led to linear changes in both the photometric and geometric effects. Varying geometric context did not produce a statistically reliable change in either the photometric or geometric effects.

  16. PNN NGC 246: A Complex Photometric Behaviour That Requires Wet

    Directory of Open Access Journals (Sweden)

    Pérez J. M. González

    2003-03-01

    Full Text Available We present a study over three single-site campaigns to investigate the photometric behaviour of the PNN NGC 246. We observed this object in 2000 and 2001. The analysis of the light curves indicates complex and variable temporal spectra. Using wavelet analysis we have found evidences for changes on time scales of hours in the 2000 dataset. The temporal spectra obtained during 2001 are quite different from the results of the previous year. The modulations in the light curve are more noticeable and the temporal spectra present a higher number of modulation frequencies. One peculiar characteristic is the presence of a variable harmonic structure related to one of these modulation frequencies. This complex photometric behaviour may be explained by a more complicated unresolved combination of modulation frequencies, but more likely due to a combination of pulsations of the star plus modulations related to interaction with a close companion, maybe indicating a disc. However, these characteristics cannot be confirmed from single site observations. The complex and variable behaviour of NGC 246 needs the WET co-operation in order to completely resolve its light curve.

  17. Monthly variations of diurnal rainfall in north coast of West Java Indonesia during boreal winter periods

    Science.gov (United States)

    Yulihastin, E.; Trismidianto

    2018-05-01

    Diurnal rainfall during the active monsoon period is usually associated with the highest convective activity that often triggers extreme rainfall. Investigating diurnal rainfall behavior in the north coast of West Java is important to recognize the behavioral trends of data leading to such extreme events in strategic West Java because the city of Jakarta is located in this region. Variability of diurnal rainfall during the period of active monsoon on December-January-February (DJF) composite during the 2000-2016 period was investigated using hourly rainfall data from Tropical Rainfall Measuring Mission (TRMM) 3B41RT dataset. Through the Empirical Mode Decomposition method was appears that the diurnal rain cycle during February has increased significantly in its amplitude and frequency. It is simultaneously shows that the indication of extreme rainfall events is related to diurnal rain divergences during February shown through phase shifts. The diurnal, semidiurnal, and terdiurnal cycles appear on the characteristics of the DJF composite rainfall data during the 2000-2016 period.The significant increases in amplitude occurred during February are the diurnal (IMF 3) and terdiurnal (IMF 1) of rainfall cycles.

  18. Defining photometric peculiar type Ia supernovae

    Energy Technology Data Exchange (ETDEWEB)

    González-Gaitán, S.; Pignata, G.; Förster, F.; Gutiérrez, C. P.; Bufano, F.; Galbany, L.; Hamuy, M.; De Jaeger, T. [Millennium Institute of Astrophysics, Casilla 36-D, Santiago (Chile); Hsiao, E. Y.; Phillips, M. M. [Carnegie Observatories, Las Campanas Observatory, Casilla 601, La Serena (Chile); Folatelli, G. [Kavli Institute for the Physics and Mathematics of the Universe, the University of Tokyo, Kashiwa 277-8583 (Kavli IPMU, WPI) (Japan); Anderson, J. P., E-mail: sgonzale@das.uchile.cl [European Southern Observatory, Alonso de Córdova 3107, Casilla 19, Santiago (Chile)

    2014-11-10

    We present a new photometric identification technique for SN 1991bg-like type Ia supernovae (SNe Ia), i.e., objects with light curve characteristics such as later primary maxima and the absence of a secondary peak in redder filters. This method is capable of selecting this sub-group from the normal type Ia population. Furthermore, we find that recently identified peculiar sub-types such as SNe Iax and super-Chandrasekhar SNe Ia have photometric characteristics similar to 91bg-like SNe Ia, namely, the absence of secondary maxima and shoulders at longer wavelengths, and can also be classified with our technique. The similarity of these different SN Ia sub-groups perhaps suggests common physical conditions. This typing methodology permits the photometric identification of peculiar SNe Ia in large upcoming wide-field surveys either to study them further or to obtain a pure sample of normal SNe Ia for cosmological studies.

  19. Photometric diversity of terrains on Triton

    Science.gov (United States)

    Hillier, J.; Veverka, J.; Helfenstein, P.; Lee, P.

    1994-01-01

    Voyager disk-resolved images of Triton in the violet (0.41 micrometers) and green (0.56 micrometer wavelengths have been analyzed to derive the photometric characteristics of terrains on Triton. Similar conclusions are found using two distinct but related definitions of photometric units, one based on color ratio and albedo properties (A. S. McEwen, 1990), the other on albedo and brightness ratios at different phase angles (P. Lee et al., 1992). A significant diversity of photometric behavior, much broader than that discovered so far on any other icy satellite, occurs among Triton's terrains. Remarkably, differences in photometric behavior do not correlate well with geologic terrain boundaries defined on the basis of surface morphology. This suggests that in most cases photometric properties on Triton are controlled by thin deposits superposed on underlying geologic units. Single scattering albedos are 0.98 or higher and asymmetry factors range from -0.35 to -0.45 for most units. The most distinct scattering behavior is exhibited by the reddish northern units already identified as the Anomalously Scattering Region (ASR), which scatters light almost isotropically with g = -0.04. In part due to the effects of Triton's clouds and haze, it is difficult to constrain the value of bar-theta, Hapke's macroscopic roughness parameter, precisely for Triton or to map differences in bar-theta among the different photometric terrains. However, our study shows that Triton must be relatively smooth, with bar-theta less than 15-20 degs and suggests that a value of 14 degs is appropriate. The differences in photometric characteristics lead to significantly different phase angle behavior for the various terrains. For example, a terrain (e.g., the ASR) that appears dark relative to another at low phase angles will reverse its contrast (become relatively brighter) at larger phase angles. The photometric parameters have been used to calculate hemispherical albedos for the units and to

  20. V 463 Cyg: revised photometric elements

    International Nuclear Information System (INIS)

    Giuricin, G.; Mardirossian, F.; Ferluga, S.

    1982-01-01

    Using Wood's (1972) model we have re-analyzed Vetesnik's (1968) two-colour photoelectric light curves of eclipsing binary V 463 Cyg. Our photometric solutions which confirm the presence of a large amount of third light do not greatly differ from previous results. The eclipsing pair appears to be composed of an A 0 primary attended by a somewhat smaller (around G 5) companion. In view of the large ratio of the radii this component cannot be in the main sequence. It seems to be more advanced in the evolution than the primary, like common secondaries of Algols, and it appears to fill its Roche lobe for our photometric mass ratio. (author)

  1. DETECTION OF KOI-13.01 USING THE PHOTOMETRIC ORBIT

    International Nuclear Information System (INIS)

    Shporer, Avi; Jenkins, Jon M.; Seader, Shawn E.; Smith, Jeffrey C.; Thompson, Susan E.; Twicken, Joseph D.; Rowe, Jason F.; Sanderfer, Dwight T.; Still, Martin D.; Welsh, William F.

    2011-01-01

    We use the KOI-13 transiting star-planet system as a test case for the recently developed BEER algorithm, aimed at identifying non-transiting low-mass companions by detecting the photometric variability induced by the companion along its orbit. Such photometric variability is generated by three mechanisms: the beaming effect, tidal ellipsoidal distortion, and reflection/heating. We use data from three Kepler quarters, from the first year of the mission, while ignoring measurements within the transit and occultation, and show that the planet's ephemeris is clearly detected. We fit for the amplitude of each of the three effects and use the beaming effect amplitude to estimate the planet's minimum mass, which results in M p sin i = 9.2 ± 1.1 M J (assuming the host star parameters derived by Szabo et al.). Our results show that non-transiting star-planet systems similar to KOI-13.01 can be detected in Kepler data, including a measurement of the orbital ephemeris and the planet's minimum mass. Moreover, we derive a realistic estimate of the amplitudes uncertainties, and use it to show that data obtained during the entire lifetime of the Kepler mission of 3.5 years will allow detecting non-transiting close-in low-mass companions orbiting bright stars, down to the few Jupiter mass level. Data from the Kepler Extended Mission, if funded by NASA, will further improve the detection capabilities.

  2. Long photometric cycles in hot algols

    Directory of Open Access Journals (Sweden)

    Mennickent R.E.

    2017-01-01

    Full Text Available We summarize the development of the field of Double Periodic Variables (DPVs, Mennickent et al. 2003 during the last fourteen years, placing these objects in the context of intermediate-mass close interacting binaries similar to β Persei (Algol and β Lyrae (Sheliak which are generally called Algols. DPVs show enigmatic long photometric cycles lasting on average about 33 times the orbital period, and have physical properties resembling, in some aspects, β Lyrae. About 200 of these objects have been found in the Galaxy and the Magellanic Clouds. Light curve models and orbitally resolved spectroscopy indicate that DPVs are semi-detached interacting binaries consisting of a near main-sequence B-type star accreting matter from a cooler giant and surrounded by an optically thick disc. This disc contributes a significant fraction of the system luminosity and its luminosity is larger than expected from the phenomenon of mass accretion alone. In some systems, an optically thin disc component is observed in well developed Balmer emission lines. The optically thick disc shows bright zones up to tens percent hotter than the disc, probably indicating shocks resulting from the gas and disc stream dynamics. We conjecture that a hotspot wind might be one of the channels for a mild systemic mass loss, since evidence for jets, winds or general mass loss has been found in β Lyrae, AUMon, HD170582, OGLE05155332-6925581 and V393 Sco. Also, theoretical work by Van Rensbergen et al. (2008 and Deschamps et al. (2013 suggests that hotspot could drive mass loss from Algols. We give special consideration to the recently published hypothesis for the long-cycle, consisting of variable mass transfer driven by a magnetic dynamo (Schleicher and Mennickent 2017. The Applegate (1992 mechanism should modify cyclically the equatorial radius of the chromospherically active donor producing cycles of enhanced mass loss through the inner Lagrangian point. Chromospheric emission in

  3. An unusual kind of diurnal streamflow variation

    Directory of Open Access Journals (Sweden)

    Cuevas Jaime G.

    2018-03-01

    Full Text Available During hydrological research in a Chilean swamp forest, we noted a pattern of higher streamflows close to midday and lower ones close to midnight, the opposite of an evapotranspiration (Et-driven cycle. We analyzed this diurnal streamflow signal (DSS, which appeared mid-spring (in the growing season. The end of this DSS coincided with a sustained rain event in autumn, which deeply affected stream and meteorological variables. A survey along the stream revealed that the DSS maximum and minimum values appeared 6 and 4 hours earlier, respectively, at headwaters located in the mountain forests/ plantations than at the control point in the swamp forest. Et in the swamp forest was higher in the morning and in the late afternoon, but this process could not influence the groundwater stage. Trees in the mountain headwaters reached their maximum Ets in the early morning and/or close to midday. Our results suggest that the DSS is a wave that moves from forests high in the mountains towards lowland areas, where Et is decoupled from the DSS. This signal delay seems to convert the link between streamflow and Et in an apparent, but spurious positive relationship. It also highlights the role of landscape heterogeneity in shaping hydrological processes.

  4. The VISTA ZYJHKs photometric system: calibration from 2MASS

    Science.gov (United States)

    González-Fernández, C.; Hodgkin, S. T.; Irwin, M. J.; González-Solares, E.; Koposov, S. E.; Lewis, J. R.; Emerson, J. P.; Hewett, P. C.; Yoldaş, A. K.; Riello, M.

    2018-03-01

    In this paper, we describe the routine photometric calibration of data taken with the VISTA infrared camera (VIRCAM) instrument on the ESO Visible and Infrared Survey Telescope for Astronomy (VISTA) telescope. The broad-band ZYJHKs data are directly calibrated from Two Micron all Sky Survey (2MASS) point sources visible in every VISTA image. We present the empirical transformations between the 2MASS and VISTA, and Wide-Field Camera and VISTA, photometric systems for regions of low reddening. We investigate the long-term performance of VISTA+VIRCAM. An investigation of the dependence of the photometric calibration on interstellar reddening leads to these conclusions: (1) For all broad-band filters, a linear colour-dependent correction compensates the gross effects of reddening where E(B - V) < 5.0. (2) For Z and Y, there is a significantly larger scatter above E(B - V) = 5.0, and insufficient measurements to adequately constrain the relation beyond this value. (3) The JHKs filters can be corrected to a few per cent up to E(B - V) = 10.0. We analyse spatial systematics over month-long time-scales, both inter- and intradetector and show that these are present only at very low levels in VISTA. We monitor and remove residual detector-to-detector offsets. We compare the calibration of the main pipeline products: pawprints and tiles. We show how variable seeing and transparency affect the final calibration accuracy of VISTA tiles, and discuss a technique, grouting, for mitigating these effects. Comparison between repeated reference fields is used to demonstrate that the VISTA photometry is precise to better than ≃ 2 per cent for the YJHKs bands and 3 per cent for the Z bands. Finally, we present empirically determined offsets to transform VISTA magnitudes into a true Vega system.

  5. On the realistic validation of photometric redshifts

    DEFF Research Database (Denmark)

    Beck, R.; Lin, C. A.; Ishida, E. E.O.

    2017-01-01

    test of photo-z methods. Using photometry from the Sloan Digital Sky Survey and spectroscopy from a collection of sources, we constructed data sets that mimic the biases between the underlying probability distribution of the real spectroscopic and photometric sample. We demonstrate the potential...

  6. Interstellar Extinction in the Gaia Photometric Systems

    Directory of Open Access Journals (Sweden)

    Bridžius A.

    2003-12-01

    Full Text Available Three medium-band photometric systems proposed for the Gaia space mission are intercompared in determining color excesses for stars of spectral classes from O to M at V = 18 mag. A possibility of obtaining a three-dimensional map of the interstellar extinction is discussed.

  7. Photometric study of uranyl-terramycin complex

    Energy Technology Data Exchange (ETDEWEB)

    Sankara Reddy, P B [Government Coll., Cuddapah, Andhra Pradesh (India). Dept. of Chemistry; Reddy, A V.R.; Brahmaji Rao, S [SVU Autonomous Post-Graduate Centre, Anantapur (India). Dept. of Chemistry

    1980-04-01

    The spectrophotometric investigation of uranylterramycin complex in solution has been studied photometrically at pH 1.3. The composition of the complex is established by Job's and Slope ratio methods as 1:1. The stability constant calculated from the data obtained in Job's method is 1.9 x 10/sup 3/. Beer's law is obeyed.

  8. Diurnal variation of zooplankton off Versova (Bombay)

    Digital Repository Service at National Institute of Oceanography (India)

    Gajbhiye, S.N.; Nair, V.R.; Desai, B.N.

    Physicochemical parameters and diurnal variaion of zooplankton were studied off Versova on 17/18 February 1981. Salinity and dissolved oxygen showed limited variation during the period of study. Nutrient values followed the tidal rhythm and high...

  9. Modelled and Observed Diurnal SST Signals: "SSTDV:R.EX.-IM.A.M." Project Preliminary Results

    DEFF Research Database (Denmark)

    Karagali, Ioanna; Høyer, Jacob; LeBorgne, Pierre

    2013-01-01

    This study presents some of the preliminary results from the ESA Support To Science Element (STSE) funded project on the Diurnal Variability of the Sea Surface Temperature, regarding its Regional Extend and Implications in Atmospheric Modelling (SSTDV:R.EX.–IM.A.M.). During this phase of the proj......This study presents some of the preliminary results from the ESA Support To Science Element (STSE) funded project on the Diurnal Variability of the Sea Surface Temperature, regarding its Regional Extend and Implications in Atmospheric Modelling (SSTDV:R.EX.–IM.A.M.). During this phase...

  10. Seasonal and diurnal variations of ocular pressure in ocular hypertensive subjects in Pakistan.

    Science.gov (United States)

    Qureshi, I A; Xiao, R X; Yang, B H; Zhang, J; Xiang, D W; Hui, J L

    1999-05-01

    Studies have been shown that intraocular pressure (IOP) shows a diurnal variation in ocular hypertensive subjects, but the amount of change differs from study to study. In recent years it has been noted that intraocular pressure is a dynamic function and is subjected to many influences both acutely and over the long term. The variability in the results may be due to negligence of factors that can affect IOP. Moreover, seasonal variations in the ocular hypertensive subjects have never been described. After placing control on those factors that can affect IOP, this study investigated seasonal and diurnal variations in IOP of ocular hypertensive subjects. IOP was measured each month over the course of 12 months with the Goldmann applanation tonometer in 91 ocular hypertensive male subjects. To see the diurnal changes, subjects were asked to stay in the hospital for 24 hours. The average IOP in the winter months was higher than those in spring, summer, and autumn. The IOP difference between winter and summer was (mean +/- sem) 2.9 +/- 0.9 mmHg (p < 0.001). The peak of mean IOP in diurnal variation curve (25.7 +/- 1.2 mmHg) appeared in the morning when the subjects had just awaken. The mean diurnal variation was found to be 4.2 +/- 0.6 mmHg (p < 0.001). This study confirms that seasons influence IOP and it shows diurnal variations. As compared to other nations, diurnal variations in ocular hypertensive subjects seem to be somewhat less in Pakistan. Knowledge of the seasonal and diurnal variations in IOP may help glaucoma screeners.

  11. THE POLARIMETRIC AND PHOTOMETRIC VARIABILITY OF HH 30

    International Nuclear Information System (INIS)

    Duran-Rojas, MarIa Carolina; Watson, Alan M.; Stapelfeldt, Karl R.; Hiriart, David

    2009-01-01

    We have obtained ground-based photopolarimetry of the young stellar object HH 30 over the course of one year. Our observations reveal the presence of a dominant periodic modulation of the polarization with a period of 7.49 ± 0.04 days or one of the aliases of this period close to 1 day. There are also suggestions of a weak periodic modulation in the photometry with the same period but a phase displaced by one quarter of a period. These results are in agreement with the lighthouse model for HH 30, in which a beam or shadow from a central source sweeps across the disk. Our observations by themselves appear to be consistent with both of the mechanisms that have been proposed for the lighthouse-asymmetric accretion hot spots on the star or orbiting clumps or voids in the disk-and provide strong quantitative constraints for future models.

  12. Photometric Variability of Four Coronally Active Stars J. C. Pandey ...

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    ray surveys with the Einstein and the ROSAT observatories and found to be associated with bright late- type stars. Many of these stars have not been studied in detail for their chromospheric and coronal activity, and their nature is not fully ...

  13. No diurnal variation in rate or carbon isotope composition of soil respiration in a boreal forest

    International Nuclear Information System (INIS)

    Betson, N.R.; Gottlicher, S.G.; Hogberg, P.; Hall, M.; Wallin, G.; Richter, A.

    2007-01-01

    This study evaluated the diurnal variability in the rate and stable carbon isotope ratio ((delta) 13 C) of soil respiration in a northern boreal forest, measured with opaque chambers after the removal of understory vegetation. The experiment was conducted in June and August 2004 at the Picea abies L. Karst-dominated Flakaliden Research Forest in northern Sweden, using unfertilized girdled-tree plots and unfertilized non-girdled tree plots. Soil respiration and (delta) 13 C of soil-respired carbon dioxide (CO 2 ) were measured every 4 hours on 6 plots, with a total of 11 sampling times over each 48 hour period. The purpose was to clarify an earlier study regarding the origin of diurnal patterns of soil CO 2 flux. This study explored whether the diurnal patterns were the result of photosynthetic CO 2 uptake during the day by the understory or whether there were underlying trends in soil respiration driven by plant root allocation. The sampling campaigns undertaken in this study investigated whether diurnal variations in soil respiration rate and (delta) 13 C exist in this ecosystem when no understory vegetation is present. Shoot photosynthesis and environmental parameters were measured simultaneously. Despite significant variations in climatic conditions and shoot photosynthetic rates in non-girdled trees, no diurnal patterns in soil respiration rates and (delta) 13 C were noted in either treatment. The lack of detectable diurnal changes in both treatments indicates that modeling of daily boreal forest carbon balances based on single instantaneous measurements are unlikely to be misconstrued by substantial diurnal trends. However, it was suggested that spatial variable should be accounted for, given the large standard errors. The impact of tree girdling on soil respiration rates also emphasized the significance of canopy photosynthesis in driving soil processes. 37 refs., 2 figs

  14. Diurnal and semi-diurnal tidal currents in the deep mid-Arabian sea

    Digital Repository Service at National Institute of Oceanography (India)

    Shenoi, S.S.C.; Gouveia, A.D.; Shetye, S.R.

    Current meter records from two depths, approximately 1000 m, at three mooring in the deep mid-Arabian Sea were used to study tidal components. Tidal ellipses for the semi-diurnal (M2, S2 and K2) and the diurnal (K1 and P1) tidal constituents have...

  15. Application of photometric models to asteroids

    International Nuclear Information System (INIS)

    Bowell, E.; Dominque, D.; Hapke, B.

    1989-01-01

    The way an asteroid or other atmosphereless solar system body varies in brightness in response to changing illumination and viewing geometry depends in a very complicated way on the physical and optical properties of its surface and on its overall shape. The authors summarize the formulation and application of recent photometric models by Hapke and by Lumme and Bowell. In both models, the brightness of a rough and porous surface is parametrized in terms of the optical properties of individual particles, by shadowing between particles, and by the way in which light scattered among collections of particles. Both models succeed in their goal of fitting the observed photometric behavior of a wide variety of bodies, but neither has led to a very complete understanding of the properties of asteroid regoliths, primarily because in most cases the parameters in the present models cannot be adequately constrained by observations of integral brightness alone over a restricted range of phase angles

  16. Stellar physics with the ALHAMBRA photometric system

    International Nuclear Information System (INIS)

    Villegas, T Aparicio; Alfaro, E J; Moles, M; Benítez, N; Perea, J; Olmo, A del; Cristóbal-Hornillos, D; Cervio, M; Delgado, R M González; Márquez, I; Masegosa, J; Prada, F; Cabrera-Caño, J; Fernández-Soto, A; Aguerri, J A L; Cepa, J; Broadhurst, T; Castander, F J; Infante, L; Martínez, V J

    2011-01-01

    The ALHAMBRA photometric system was specifically designed to perform a tomography of the Universe in some selected areas. Although mainly designed for extragalactic purposes, its 20 contiguous, equal-width, medium-band photometric system in the optical wavelength range, shows a great capacity for stellar classification. In this contribution we propose a methodology for stellar classification and physical parameter estimation (T eff , log g, [Fe/H], and color excess E(B – V)) based on 18 independent reddening-free Q-values from the ALHAMBRA photometry. Based on the theoretical Spectral library BaSeL 2.2, and applied to 288 stars from the Next Generation spectral Library (NGSL), we discuss the reliability of the method and its dependence on the extinction law used.

  17. Photometric Characterization of the Dark Energy Camera

    Science.gov (United States)

    Bernstein, G. M.; Abbott, T. M. C.; Armstrong, R.; Burke, D. L.; Diehl, H. T.; Gruendl, R. A.; Johnson, M. D.; Li, T. S.; Rykoff, E. S.; Walker, A. R.; Wester, W.; Yanny, B.

    2018-05-01

    We characterize the variation in photometric response of the Dark Energy Camera (DECam) across its 520 Mpix science array during 4 years of operation. These variations are measured using high signal-to-noise aperture photometry of >107 stellar images in thousands of exposures of a few selected fields, with the telescope dithered to move the sources around the array. A calibration procedure based on these results brings the rms variation in aperture magnitudes of bright stars on cloudless nights down to 2–3 mmag, with color corrections; and the use of an aperture-correction proxy. The DECam response pattern across the 2° field drifts over months by up to ±9 mmag, in a nearly wavelength-independent low-order pattern. We find no fundamental barriers to pushing global photometric calibrations toward mmag accuracy.

  18. A MACHINE-LEARNING METHOD TO INFER FUNDAMENTAL STELLAR PARAMETERS FROM PHOTOMETRIC LIGHT CURVES

    International Nuclear Information System (INIS)

    Miller, A. A.; Bloom, J. S.; Richards, J. W.; Starr, D. L.; Lee, Y. S.; Butler, N. R.; Tokarz, S.; Smith, N.; Eisner, J. A.

    2015-01-01

    A fundamental challenge for wide-field imaging surveys is obtaining follow-up spectroscopic observations: there are >10 9 photometrically cataloged sources, yet modern spectroscopic surveys are limited to ∼few× 10 6 targets. As we approach the Large Synoptic Survey Telescope era, new algorithmic solutions are required to cope with the data deluge. Here we report the development of a machine-learning framework capable of inferring fundamental stellar parameters (T eff , log g, and [Fe/H]) using photometric-brightness variations and color alone. A training set is constructed from a systematic spectroscopic survey of variables with Hectospec/Multi-Mirror Telescope. In sum, the training set includes ∼9000 spectra, for which stellar parameters are measured using the SEGUE Stellar Parameters Pipeline (SSPP). We employed the random forest algorithm to perform a non-parametric regression that predicts T eff , log g, and [Fe/H] from photometric time-domain observations. Our final optimized model produces a cross-validated rms error (RMSE) of 165 K, 0.39 dex, and 0.33 dex for T eff , log g, and [Fe/H], respectively. Examining the subset of sources for which the SSPP measurements are most reliable, the RMSE reduces to 125 K, 0.37 dex, and 0.27 dex, respectively, comparable to what is achievable via low-resolution spectroscopy. For variable stars this represents a ≈12%-20% improvement in RMSE relative to models trained with single-epoch photometric colors. As an application of our method, we estimate stellar parameters for ∼54,000 known variables. We argue that this method may convert photometric time-domain surveys into pseudo-spectrographic engines, enabling the construction of extremely detailed maps of the Milky Way, its structure, and history

  19. Uncertain Photometric Redshifts with Deep Learning Methods

    Science.gov (United States)

    D'Isanto, A.

    2017-06-01

    The need for accurate photometric redshifts estimation is a topic that has fundamental importance in Astronomy, due to the necessity of efficiently obtaining redshift information without the need of spectroscopic analysis. We propose a method for determining accurate multi-modal photo-z probability density functions (PDFs) using Mixture Density Networks (MDN) and Deep Convolutional Networks (DCN). A comparison with a Random Forest (RF) is performed.

  20. Photometric Defocus Observations of Transiting Extrasolar Planets

    Directory of Open Access Journals (Sweden)

    Tobias C. Hinse

    2015-03-01

    Full Text Available We have carried out photometric follow-up observations of bright transiting extrasolar planets using the CbNUOJ 0.6 m telescope. We have tested the possibility of obtaining high photometric precision by applying the telescope defocus technique, allowing the use of several hundred seconds in exposure time for a single measurement. We demonstrate that this technique is capable of obtaining a root-mean-square scatter of sub-millimagnitude order over several hours for a V ~10 host star, typical for transiting planets detected from ground-based survey facilities. We compared our results with transit observations from a telescope operated in in-focus mode. High photometric precision was obtained due to the collection of a larger amount of photons, resulting in a higher signal compared to other random and systematic noise sources. Accurate telescope tracking is likely to further contribute to lowering systematic noise by exposing the same pixels on the CCD. Furthermore, a longer exposure time helps reduce the effect of scintillation noise which otherwise has a significant effect for small-aperture telescopes operated in in-focus mode. Finally we present the results of modelling four light-curves in which a root-mean-square scatter of 0.70 to 2.3 milli-magnitudes was achieved.

  1. Can Selforganizing Maps Accurately Predict Photometric Redshifts?

    Science.gov (United States)

    Way, Michael J.; Klose, Christian

    2012-01-01

    We present an unsupervised machine-learning approach that can be employed for estimating photometric redshifts. The proposed method is based on a vector quantization called the self-organizing-map (SOM) approach. A variety of photometrically derived input values were utilized from the Sloan Digital Sky Survey's main galaxy sample, luminous red galaxy, and quasar samples, along with the PHAT0 data set from the Photo-z Accuracy Testing project. Regression results obtained with this new approach were evaluated in terms of root-mean-square error (RMSE) to estimate the accuracy of the photometric redshift estimates. The results demonstrate competitive RMSE and outlier percentages when compared with several other popular approaches, such as artificial neural networks and Gaussian process regression. SOM RMSE results (using delta(z) = z(sub phot) - z(sub spec)) are 0.023 for the main galaxy sample, 0.027 for the luminous red galaxy sample, 0.418 for quasars, and 0.022 for PHAT0 synthetic data. The results demonstrate that there are nonunique solutions for estimating SOM RMSEs. Further research is needed in order to find more robust estimation techniques using SOMs, but the results herein are a positive indication of their capabilities when compared with other well-known methods

  2. Photometric Calibration of Consumer Video Cameras

    Science.gov (United States)

    Suggs, Robert; Swift, Wesley, Jr.

    2007-01-01

    Equipment and techniques have been developed to implement a method of photometric calibration of consumer video cameras for imaging of objects that are sufficiently narrow or sufficiently distant to be optically equivalent to point or line sources. Heretofore, it has been difficult to calibrate consumer video cameras, especially in cases of image saturation, because they exhibit nonlinear responses with dynamic ranges much smaller than those of scientific-grade video cameras. The present method not only takes this difficulty in stride but also makes it possible to extend effective dynamic ranges to several powers of ten beyond saturation levels. The method will likely be primarily useful in astronomical photometry. There are also potential commercial applications in medical and industrial imaging of point or line sources in the presence of saturation.This development was prompted by the need to measure brightnesses of debris in amateur video images of the breakup of the Space Shuttle Columbia. The purpose of these measurements is to use the brightness values to estimate relative masses of debris objects. In most of the images, the brightness of the main body of Columbia was found to exceed the dynamic ranges of the cameras. A similar problem arose a few years ago in the analysis of video images of Leonid meteors. The present method is a refined version of the calibration method developed to solve the Leonid calibration problem. In this method, one performs an endto- end calibration of the entire imaging system, including not only the imaging optics and imaging photodetector array but also analog tape recording and playback equipment (if used) and any frame grabber or other analog-to-digital converter (if used). To automatically incorporate the effects of nonlinearity and any other distortions into the calibration, the calibration images are processed in precisely the same manner as are the images of meteors, space-shuttle debris, or other objects that one seeks to

  3. Photometric observations of nine Transneptunian objects and Centaurs

    Science.gov (United States)

    Hromakina, T.; Perna, D.; Belskaya, I.; Dotto, E.; Rossi, A.; Bisi, F.

    2018-02-01

    We present the results of photometric observations of six Transneptunian objects and three Centaurs, estimations of their rotational periods and corresponding amplitudes. For six of them we present also lower limits of density values. All observations were made using 3.6-m TNG telescope (La Palma, Spain). For four objects - (148975) 2001 XA255, (281371) 2008 FC76, (315898) 2008 QD4, and 2008 CT190 - the estimation of short-term variability was made for the first time. We confirm rotation period values for two objects: (55636) 2002 TX300 and (202421) 2005 UQ513, and improve the precision of previously reported rotational period values for other three - (120178) 2003 OP32, (145452) 2005 RN43, (444030) 2004 NT33 - by using both our and literature data. We also discuss here that small distant bodies, similar to asteroids in the Main belt, tend to have double-peaked rotational periods caused by the elongated shape rather than surface albedo variations.

  4. DES Science Portal: Computing Photometric Redshifts

    Energy Technology Data Exchange (ETDEWEB)

    Gschwend, Julia [LIneA, Rio de Janeiro

    2016-01-01

    An important challenge facing photometric surveys for cosmological purposes, such as the Dark Energy Survey (DES), is the need to produce reliable photometric redshifts (photo-z). The choice of adequate algorithms and configurations and the maintenance of an up-to-date spectroscopic database to build training sets, for example, are challenging tasks when dealing with large amounts of data that are regularly updated and constantly growing. In this paper, we present the first of a series of tools developed by DES, provided as part of the DES Science Portal, an integrated web-based data portal developed to facilitate the scientific analysis of the data, while ensuring the reproducibility of the analysis. We present the DES Science Portal photometric redshift tools, starting from the creation of a spectroscopic sample to training the neural network photo-z codes, to the final estimation of photo-zs for a large photometric catalog. We illustrate this operation by calculating well calibrated photo-zs for a galaxy sample extracted from the DES first year (Y1A1) data. The series of processes mentioned above is run entirely within the Portal environment, which automatically produces validation metrics, and maintains the provenance between the different steps. This system allows us to fine tune the many steps involved in the process of calculating photo-zs, making sure that we do not lose the information on the configurations and inputs of the previous processes. By matching the DES Y1A1 photometry to a spectroscopic sample, we define different training sets that we use to feed the photo-z algorithms already installed at the Portal. Finally, we validate the results under several conditions, including the case of a sample limited to i<22.5 with the color properties close to the full DES Y1A1 photometric data. This way we compare the performance of multiple methods and training configurations. The infrastructure presented here is an effcient way to test several methods of

  5. Photometry of Variable Stars, and System Transformability Over Long Time Intervals

    Directory of Open Access Journals (Sweden)

    Sterken C.

    2003-12-01

    Full Text Available The fundamental problem of long-term photometric monitoring of variable stars and of multi-wavelength photometric campaigns is the problem of bringing the data to a common standard. Such homogenization can be achieved only when the measurements are made in photometric systems that are truly transformable. This fundamental problem is of a technical nature, and photometric observers, sometimes, are not aware of the problems. This frequently leads to over-interpretation of the data.

  6. Diurnal variations of tritium uptake by plants

    International Nuclear Information System (INIS)

    Hettinger, M.; Diabate, S.; Strack, S.

    1991-02-01

    The influence of the diurnal cycle is important for the behaviour of environmental tritium in the vegetation. A mathematical model has been used to calculate the deposition of tritium in plants as a function of diurnal variations of climatic parameters. The necessary physiological parameters (relationship of net photosynthesis and growth) were derived from growth experiments for tomatoes and maize. In chamber experiments, tomato and maize plants were exposed to tritium with natural diurnal variations of the climatic conditions. Within the range of standard deviations the measured concentrations of tritium in tissue free water of tomatoes correspond well to the estimated values. Furthermore, the incorporation into non-exchangeable organically bound tritium (OBT nx) can be sufficiently modelled and explained. There are deviations from the estimated concentrations in some parts of maize leaves. (orig.) [de

  7. ANALYSIS THE DIURNAL VARIATIONS ON SELECTED PHYSICAL AND PHYSIOLOGICAL PARAMETERS

    Directory of Open Access Journals (Sweden)

    A. MAHABOOBJAN

    2010-12-01

    Full Text Available The purpose of the study was to analyze the diurnal variations on selected physical and physiological parameters such as speed, explosive power, resting heart rate and breath holding time among college students. To achieve the purpose of this study, a total of twenty players (n=20 from Government Arts College, Salem were selected as subjects To study the diurnal variation of the players on selected physiological and performance variables, the data were collected 4 times a day with every four hours in between the times it from 6.00 to 18.00 hours were selected as another categorical variable. One way repeated measures (ANOVA was used to analyze the data. If the obtained F-ratio was significant, Seheffe’s post-hoc test was used to find out the significant difference if anyamong the paired means. The level of significance was fixed at.05 level. It has concluded that both physical and physiological parameters were significantly deferred with reference to change of temperature in a day

  8. Global evaluation of ammonia bidirectional exchange and livestock diurnal variation schemes

    Science.gov (United States)

    Bidirectional air–surface exchange of ammonia (NH3) has been neglected in many air quality models. In this study, we implement the bidirectional exchange of NH3 in the GEOS-Chem global chemical transport model. We also introduce an updated diurnal variability scheme for NH3...

  9. Photometric Exoplanet Characterization and Multimedia Astronomy Communication

    Science.gov (United States)

    Cartier, Kimberly M. S.

    The transit method of detecting exoplanets has dominated the search for distant worlds since the success of the Kepler space telescope and will continue to lead the field after the launch of the Transiting Exoplanet Survey Satellite in 2018. But detections are just the beginning. Transit light curves can only reveal a limited amount of information about a planet, and that information is almost entirely dependent on the properties of the host star or stars. This dissertation discusses follow-up techniques to more precisely characterize transiting planets using photometric observations. A high-resolution follow-up imaging program using the Hubble Space Telescope (HST) searched for previously unknown stars nearby the hosts of small and cool Kepler exoplanets and observed a higher-than-expected occurrence rate of stellar multiplicity. The rate of previously unknown stellar multiples has strong implications for the size and habitability of the orbiting planets. Three systems with newly discovered stellar multiplicity, Kepler-296 (2 stars, 5 planets), KOI-2626 (3 stars, 1 planet), and KOI-3049 (2 stars, 1 planet), were characterized in more detail. In the cases of Kepler-296 and KOI-2626, some of the planets lost their previous habitable zone status because of host star ambiguity. Next, the ultra-short period, ultra-hot Jupiter WASP-103b was used as a casestudy to test for the presence of a stratospheric temperature inversion through dayside emission spectroscopy using HST. WASP-103b's near-infrared emission spectrum is consistent with an isothermal or thermally-inverted atmosphere and shows no significant broadband water absorption feature. Detection of an anomalously strong "super- Rayleigh" slope in its optical transmission spectrum prompted follow-up transmission spectroscopy of WASP-103b's atmosphere using the MINiature Radial Velocity Array (MINERVA), which tentatively verified the unexplained "super-Rayleigh" spectral slope. The final follow-up technique for

  10. RECONSTRUCTING THE PHOTOMETRIC LIGHT CURVES OF EARTH AS A PLANET ALONG ITS HISTORY

    International Nuclear Information System (INIS)

    Sanromá, E.; Pallé, E.

    2012-01-01

    By utilizing satellite-based estimations of the distribution of clouds, we have studied Earth's large-scale cloudiness behavior according to latitude and surface types (ice, water, vegetation, and desert). These empirical relationships are used here to reconstruct the possible cloud distribution of historical epochs of Earth's history such as the Late Cretaceous (90 Ma ago), the Late Triassic (230 Ma ago), the Mississippian (340 Ma ago), and the Late Cambrian (500 Ma ago), when the landmass distributions were different from today's. With this information, we have been able to simulate the globally integrated photometric variability of the planet at these epochs. We find that our simple model reproduces well the observed cloud distribution and albedo variability of the modern Earth. Moreover, the model suggests that the photometric variability of the Earth was probably much larger in past epochs. This enhanced photometric variability could improve the chances for the difficult determination of the rotational period and the identification of continental landmasses for a distant planets.

  11. Statistical learning modeling method for space debris photometric measurement

    Science.gov (United States)

    Sun, Wenjing; Sun, Jinqiu; Zhang, Yanning; Li, Haisen

    2016-03-01

    Photometric measurement is an important way to identify the space debris, but the present methods of photometric measurement have many constraints on star image and need complex image processing. Aiming at the problems, a statistical learning modeling method for space debris photometric measurement is proposed based on the global consistency of the star image, and the statistical information of star images is used to eliminate the measurement noises. First, the known stars on the star image are divided into training stars and testing stars. Then, the training stars are selected as the least squares fitting parameters to construct the photometric measurement model, and the testing stars are used to calculate the measurement accuracy of the photometric measurement model. Experimental results show that, the accuracy of the proposed photometric measurement model is about 0.1 magnitudes.

  12. PHOTOMETRIC OBSERVATIONS OF SELECTED, OPTICALLY BRIGHT QUASARS FOR SPACE INTERFEROMETRY MISSION AND OTHER FUTURE CELESTIAL REFERENCE FRAMES

    International Nuclear Information System (INIS)

    Ojha, Roopesh; Zacharias, Norbert; Hennessy, Gregory S.; Gaume, Ralph A.; Johnston, Kenneth J.

    2009-01-01

    Photometric observations of 235 extragalactic objects that are potential targets for the Space Interferometry Mission (SIM) are presented. Mean B, V, R, I magnitudes at the 5% level are obtained at 1-4 epochs between 2005 and 2007 using the 1 m telescopes at Cerro Tololo Inter-American Observatory and the Naval Observatory Flagstaff Station. Of the 134 sources that have V magnitudes in the Veron and Veron-Cetty catalog, a difference of over 1.0 mag is found for the observed-catalog magnitudes for about 36% of the common sources, and 10 sources show over 3 mag difference. Our first set of observations presented here form the basis of a long-term photometric variability study of the selected reference frame sources to assist in mission target selection and to support QSO multicolor photometric variability studies in general.

  13. Diurnal variations in the UV albedo of arctic snow

    Directory of Open Access Journals (Sweden)

    O. Meinander

    2008-11-01

    Full Text Available The relevance of snow for climate studies is based on its physical properties, such as high surface reflectivity. Surface ultraviolet (UV albedo is an essential parameter for various applications based on radiative transfer modeling. Here, new continuous measurements of the local UV albedo of natural Arctic snow were made at Sodankylä (67°22'N, 26°39'E, 179 m a.s.l. during the spring of 2007. The data were logged at 1-min intervals. The accumulation of snow was up to 68 cm. The surface layer thickness varied from 0.5 to 35 cm with the snow grain size between 0.2 and 2.5 mm. The midday erythemally weighted UV albedo ranged from 0.6 to 0.8 in the accumulation period, and from 0.5 to 0.7 during melting. During the snow melt period, under cases of an almost clear sky and variable cloudiness, an unexpected diurnal decrease of 0.05 in albedo soon after midday, and recovery thereafter, was detected. This diurnal decrease in albedo was found to be asymmetric with respect to solar midday, thus indicating a change in the properties of the snow. Independent UV albedo results with two different types of instruments confirm these findings. The measured temperature of the snow surface was below 0°C on the following mornings. Hence, the reversible diurnal change, evident for ~1–2 h, could be explained by the daily metamorphosis of the surface of the snowpack, in which the temperature of the surface increases, melting some of the snow to liquid water, after which the surface freezes again.

  14. Diurnal levels of immunoreactive erythropoietin in normal subjects and subjects with chronic lung disease

    Energy Technology Data Exchange (ETDEWEB)

    Miller, M.E.; Garcia, J.F.; Cohen, R.A.; Cronkite, E.P.; Moccia, G.; Acevedo, J.

    1981-10-01

    Serum levels of immunoreactive erythropoietin (Ep) were measured in 48 normal male and female volunteers, ages 20-60 years, to establish a control value for Ep of 18.5 +/- 5.0 (mean +/- SD) mU/ml. Levels of the hormone were also measured sequentially over a 24 h period of time in an additional 17 normal volunteers with no diurnal variation. Diurnal levels of immunoreactive Ep were also measured in 30 subjects, with chronic lung disease. These patients, in contrast to normal subjects exhibited a diurnal variation in the level of immunoreactive Ep with peak levels occurring at midnight. The only variable measured which correlated with the serum immunoreactive Ep level in subjects with chronic lung disease was the level of carboxyhaemoglobin (P less than 0.02).

  15. Diurnal variability of upper ocean temperature and heat budget in ...

    Indian Academy of Sciences (India)

    Time-series data on upper-ocean temperature, Vessel-Mounted Acoustic Doppler Current Profiler (VM-ADCP) measured currents and surface meteorological parameters have been obtained for the first time in the southern Bay of Bengal at 7° N, 10° N, and 13° N locations along 87° E during October - November, 1998 ...

  16. Pathophysiology of diurnal drooling in Parkinson's disease

    NARCIS (Netherlands)

    Kalf, J.G.; Munneke, M.; Engel-Hoek, L. van den; Swart, B.J.M. de; Borm, G.F.; Bloem, B.R.; Zwarts, M.J.

    2011-01-01

    Drooling is an incapacitating feature of Parkinson's disease. Better pathophysiological insights are needed to improve treatment. In this study, we tested the hypothesis that the cause of drooling is multifactorial. We examined 15 patients with Parkinson's disease with distinct diurnal saliva loss

  17. Robust fitting of diurnal brightness temperature cycle

    CSIR Research Space (South Africa)

    Udahemuka, G

    2007-11-01

    Full Text Available for a pixel concerned. Robust fitting of observed Diurnal Temperature Cycle (DTC) taken over a day of a given pixel without cloud cover and other abnormally conditions such as fire can give a data based brightness temperature model for a given pixel...

  18. Scale interactions on diurnal toseasonal timescales and their relevanceto model systematic errors

    Directory of Open Access Journals (Sweden)

    G. Yang

    2003-06-01

    Full Text Available Examples of current research into systematic errors in climate models are used to demonstrate the importance of scale interactions on diurnal,intraseasonal and seasonal timescales for the mean and variability of the tropical climate system. It has enabled some conclusions to be drawn about possible processes that may need to be represented, and some recommendations to be made regarding model improvements. It has been shown that the Maritime Continent heat source is a major driver of the global circulation but yet is poorly represented in GCMs. A new climatology of the diurnal cycle has been used to provide compelling evidence of important land-sea breeze and gravity wave effects, which may play a crucial role in the heat and moisture budget of this key region for the tropical and global circulation. The role of the diurnal cycle has also been emphasized for intraseasonal variability associated with the Madden Julian Oscillation (MJO. It is suggested that the diurnal cycle in Sea Surface Temperature (SST during the suppressed phase of the MJO leads to a triggering of cumulus congestus clouds, which serve to moisten the free troposphere and hence precondition the atmosphere for the next active phase. It has been further shown that coupling between the ocean and atmosphere on intraseasonal timescales leads to a more realistic simulation of the MJO. These results stress the need for models to be able to simulate firstly, the observed tri-modal distribution of convection, and secondly, the coupling between the ocean and atmosphere on diurnal to intraseasonal timescales. It is argued, however, that the current representation of the ocean mixed layer in coupled models is not adequate to represent the complex structure of the observed mixed layer, in particular the formation of salinity barrier layers which can potentially provide much stronger local coupling between the atmosphere and ocean on diurnal to intraseasonal timescales.

  19. Impact of assimilation window length on diurnal features in a Mars atmospheric analysis

    Directory of Open Access Journals (Sweden)

    Yongjing Zhao

    2015-05-01

    Full Text Available Effective simulation of diurnal variability is an important aspect of many geophysical data assimilation systems. For the Martian atmosphere, thermal tides are particularly prominent and contribute much to the Martian atmospheric circulation, dynamics and dust transport. To study the Mars diurnal variability and Mars thermal tides, the Geophysical Fluid Dynamics Laboratory Mars Global Climate Model with the 4D-local ensemble transform Kalman filter (4D-LETKF is used to perform an analysis assimilating spacecraft temperature retrievals. We find that the use of a ‘traditional’ 6-hr assimilation cycle induces spurious forcing of a resonantly enhanced semi-diurnal Kelvin waves represented in both surface pressure and mid-level temperature by forming a wave 4 pattern in the diurnal averaged analysis increment that acts as a ‘topographic’ stationary forcing. Different assimilation window lengths in the 4D-LETKF are introduced to remove the artificially induced resonance. It is found that short assimilation window lengths not only remove the spurious resonance, but also push the migrating semi-diurnal temperature variation at 50 Pa closer to the estimated ‘true’ tides even in the absence of a radiatively active water ice cloud parameterisation. In order to compare the performance of different assimilation window lengths, short-term to mid-range forecasts based on the hour 00 and 12 assimilation are evaluated and compared. Results show that during Northern Hemisphere summer, it is not the assimilation window length, but the radiatively active water ice clouds that influence the model prediction. A ‘diurnal bias correction’ that includes bias correction fields dependent on the local time is shown to effectively reduce the forecast root mean square differences between forecasts and observations, compensate for the absence of water ice cloud parameterisation and enhance Martian atmosphere prediction. The implications of these results for

  20. A CRITICAL ASSESSMENT OF PHOTOMETRIC REDSHIFT METHODS: A CANDELS INVESTIGATION

    International Nuclear Information System (INIS)

    Dahlen, Tomas; Ferguson, Henry C.; Mobasher, Bahram; Faber, Sandra M.; Barro, Guillermo; Guo, Yicheng; Finkelstein, Steven L.; Finlator, Kristian; Fontana, Adriano; Gruetzbauch, Ruth; Johnson, Seth; Pforr, Janine; Dickinson, Mark E.; Salvato, Mara; Wuyts, Stijn; Wiklind, Tommy; Acquaviva, Viviana; Huang, Jiasheng; Huang, Kuang-Han; Newman, Jeffrey A.

    2013-01-01

    We present results from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) photometric redshift methods investigation. In this investigation, the results from 11 participants, each using a different combination of photometric redshift code, template spectral energy distributions (SEDs), and priors, are used to examine the properties of photometric redshifts applied to deep fields with broadband multi-wavelength coverage. The photometry used includes U-band through mid-infrared filters and was derived using the TFIT method. Comparing the results, we find that there is no particular code or set of template SEDs that results in significantly better photometric redshifts compared to others. However, we find that codes producing the lowest scatter and outlier fraction utilize a training sample to optimize photometric redshifts by adding zero-point offsets, template adjusting, or adding extra smoothing errors. These results therefore stress the importance of the training procedure. We find a strong dependence of the photometric redshift accuracy on the signal-to-noise ratio of the photometry. On the other hand, we find a weak dependence of the photometric redshift scatter with redshift and galaxy color. We find that most photometric redshift codes quote redshift errors (e.g., 68% confidence intervals) that are too small compared to that expected from the spectroscopic control sample. We find that all codes show a statistically significant bias in the photometric redshifts. However, the bias is in all cases smaller than the scatter; the latter therefore dominates the errors. Finally, we find that combining results from multiple codes significantly decreases the photometric redshift scatter and outlier fraction. We discuss different ways of combining data to produce accurate photometric redshifts and error estimates

  1. Photometric Properties of Network and Faculae Derived from HMI Data Compensated for Scattered Light

    Energy Technology Data Exchange (ETDEWEB)

    Criscuoli, Serena; Whitney, Taylor [National Solar Observatory, 3665 Discovery Drive, Boulder, CO 80303 (United States); Norton, Aimee [Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA, 94305 (United States)

    2017-10-01

    We report on the photometric properties of faculae and network, as observed in full-disk, scattered-light-corrected images from the Helioseismic Magnetic Imager. We use a Lucy–Richardson deconvolution routine that corrects an image in less than one second. Faculae are distinguished from network through proximity to active regions. This is the first report that full-disk observations, including center-to-limb variations, reproduce the photometric properties of faculae and network observed previously only in sub-arcsecond-resolution; small field-of-view studies, i.e. that network, as defined by distance from active regions, exhibit higher photometric contrasts. Specifically, for magnetic flux values larger than approximately 300 G, the network is brighter than faculae and the contrast differences increase toward the limb, where the network contrast is about twice the facular one. For lower magnetic flux values, network appear darker than faculae. Contrary to reports from previous full-disk observations, we also found that network exhibits a higher center-to-limb variation. Our results are in agreement with reports from simulations that indicate magnetic flux alone is a poor proxy of the photometric properties of magnetic features. We estimate that the contribution of faculae and network to Total Solar Irradiance variability of the current Cycle 24 is overestimated by at least 11%, due to the photometric properties of network and faculae not being recognized as different. This estimate is specific to the method employed in this study to reconstruct irradiance variations, so caution should be paid when extending it to other techniques.

  2. DISSECTING PHOTOMETRIC REDSHIFT FOR ACTIVE GALACTIC NUCLEUS USING XMM- AND CHANDRA-COSMOS SAMPLES

    International Nuclear Information System (INIS)

    Salvato, M.; Hasinger, G.; Ilbert, O.; Rau, A.; Brusa, M.; Bongiorno, A.; Civano, F.; Elvis, M.; Zamorani, G.; Vignali, C.; Comastri, A.; Bardelli, S.; Bolzonella, M.; Cappelluti, N.; Aussel, H.; Le Floc'h, E.; Fiore, F.; Mainieri, V.; Capak, P.; Caputi, K.

    2011-01-01

    In this paper, we release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of the Cosmic Evolution Survey (COSMOS) field. The availability of a large training set of spectroscopic redshifts that extends to faint magnitudes enabled photometric redshifts comparable to the highest quality results presently available for normal galaxies. We demonstrate that morphologically extended, faint X-ray sources without optical variability are more accurately described by a library of normal galaxies (corrected for emission lines) than by active galactic nucleus (AGN) dominated templates, even if these sources have AGN-like X-ray luminosities. Preselecting the library on the bases of the source properties allowed us to reach an accuracy σ Δz/(1+z spec ) ∼0.015 with a fraction of outliers of 5.8% for the entire Chandra-COSMOS sample. In addition, we release revised photometric redshifts for the 1735 optical counterparts of the XMM-detected sources over the entire 2 deg 2 of COSMOS. For 248 sources, our updated photometric redshift differs from the previous release by Δz > 0.2. These changes are predominantly due to the inclusion of newly available deep H-band photometry (H AB = 24 mag). We illustrate once again the importance of a spectroscopic training sample and how an assumption about the nature of a source together, with the number and the depth of the available bands, influences the accuracy of the photometric redshifts determined for AGN. These considerations should be kept in mind when defining the observational strategies of upcoming large surveys targeting AGNs, such as eROSITA at X-ray energies and the Australian Square Kilometre Array Pathfinder Evolutionary Map of the Universe in the radio band.

  3. Photometric Properties of Network and Faculae Derived from HMI Data Compensated for Scattered Light

    International Nuclear Information System (INIS)

    Criscuoli, Serena; Whitney, Taylor; Norton, Aimee

    2017-01-01

    We report on the photometric properties of faculae and network, as observed in full-disk, scattered-light-corrected images from the Helioseismic Magnetic Imager. We use a Lucy–Richardson deconvolution routine that corrects an image in less than one second. Faculae are distinguished from network through proximity to active regions. This is the first report that full-disk observations, including center-to-limb variations, reproduce the photometric properties of faculae and network observed previously only in sub-arcsecond-resolution; small field-of-view studies, i.e. that network, as defined by distance from active regions, exhibit higher photometric contrasts. Specifically, for magnetic flux values larger than approximately 300 G, the network is brighter than faculae and the contrast differences increase toward the limb, where the network contrast is about twice the facular one. For lower magnetic flux values, network appear darker than faculae. Contrary to reports from previous full-disk observations, we also found that network exhibits a higher center-to-limb variation. Our results are in agreement with reports from simulations that indicate magnetic flux alone is a poor proxy of the photometric properties of magnetic features. We estimate that the contribution of faculae and network to Total Solar Irradiance variability of the current Cycle 24 is overestimated by at least 11%, due to the photometric properties of network and faculae not being recognized as different. This estimate is specific to the method employed in this study to reconstruct irradiance variations, so caution should be paid when extending it to other techniques.

  4. A VOLUME-LIMITED PHOTOMETRIC SURVEY OF 114 γ DORADUS CANDIDATES

    International Nuclear Information System (INIS)

    Henry, Gregory W.; Fekel, Francis C.; Henry, Stephen M.

    2011-01-01

    We have carried out a photometric survey of a complete, volume-limited sample of γ Doradus candidates. The sample was extracted from the Hipparcos catalog and consists of 114 stars with colors and absolute magnitudes within the range of known γ Doradus stars and that also lie within a specified volume of 266,600 pc 3 . We devoted one year of observing time with our T12 0.8 m automatic photometric telescope to acquire nightly observations of the complete sample of stars. From these survey observations, we identify 37 stars with intrinsic variability of 0.002 mag or more. Of these 37 variables, 8 have already been confirmed as γ Doradus stars in our earlier papers; we scheduled the remaining 29 variables on our T3 0.4 m automatic telescope to acquire more intensive observations over the next two years. As promising new γ Doradus candidates were identified from the photometry, we obtained complementary spectroscopic observations of each candidate with the Kitt Peak coude feed telescope. Analysis of our new photometric and spectroscopic data reveals 15 new γ Doradus variables (and confirms two others), 8 new δ Scuti variables (and confirms one other), and 3 new variables with unresolved periodicity. Therefore, of the 114 γ Doradus candidates in our volume-limited sample, we find 25 stars that are new or previously known γ Doradus variables. This results in an incidence of 22% for γ Doradus variability among candidate field stars for this volume of the solar neighborhood. The corresponding space density of γ Doradus stars in this volume of space is 0.094 stars per 10 3 pc 3 or 94 stars per 10 6 pc 3 . We provide an updated list of 86 bright, confirmed, γ Doradus field stars.

  5. Tracking the MJO Convection and its Impact on the Diurnal Cycle over the Maritime Continent Using Satellite Observations

    Science.gov (United States)

    Kerns, B. W.; Chen, S. S.

    2017-12-01

    The Indo-Pacific Maritime Continent (MC) is the most active convection center in the tropics, and the most important modes of variability are the diurnal cycle and the Madden-Julian Oscillation (MJO). Previous studies have shown that the MC has strong diurnal variability compared with the rest of the tropics, and the diurnal cycle of convection over the MC is amplified during the passage of an MJO. One outstanding science question is how the passage of the active MJO affects the diurnal cycle. The atmospheric, upper ocean, and land surface forcing factors contributing to the diurnal cycle need to be clarified. In order to address this, large scale precipitation tracking (LPT) is used to identify MJO active and suppressed periods for 2000-2015. To document the diurnal cycle of convection during the active and suppressed periods, TRMM/GPM and mesoscale cloud cluster tracking are used. Finally, the LPT tracking is used to composite the satellite-estimated surface wind, humidity, temperature, cloud cover, and soil moisture over the islands for active versus suppressed MJO periods. In active MJO periods, the diurnal convection in the surrounding marginal seas is enhanced and the diurnal convection over land is decreased. The islands of the MC have greater soil moisture, more cloud cover, and do not warm up as much during the day, leading to a weaker afternoon maximum over land. But how is nocturnal convection over the sea increased? The largest, most mature convective cloud systems are found over the marginal seas in the early morning. This is hypothesized to mainly be a consequence of the longer life cycle of convective systems in the favorable large-scale active MJO. The propagation of the MJO across the MC is facilitated by the enhanced nocturnal deep convection over the sea. In contrast, In the suppressed period the convection is mostly daytime forced convection over land which is locked to the terrain.

  6. LED-based Photometric Stereo: Modeling, Calibration and Numerical Solutions

    DEFF Research Database (Denmark)

    Quéau, Yvain; Durix, Bastien; Wu, Tao

    2018-01-01

    We conduct a thorough study of photometric stereo under nearby point light source illumination, from modeling to numerical solution, through calibration. In the classical formulation of photometric stereo, the luminous fluxes are assumed to be directional, which is very difficult to achieve in pr...

  7. Planck 2013 results. VIII. HFI photometric calibration and mapmaking

    DEFF Research Database (Denmark)

    Planck Collaboration,; Ade, P. A. R.; Aghanim, N.

    2013-01-01

    This paper describes the processing applied to the HFI cleaned time-ordered data to produce photometrically calibrated maps. HFI observes the sky over a broad range of frequencies, from 100 to 857 GHz. To get the best accuracy on the calibration on such a large range, two different photometric ca...

  8. Photometric estimation of defect size in radiation direction

    International Nuclear Information System (INIS)

    Zuev, V.M.

    1993-01-01

    Factors, affecting accuracy of photometric estimation of defect size in radiation transmission direction, are analyzed. Experimentally obtained dependences of contrast of defect image on its size in radiation transmission direction are presented. Practical recommendations on improving accuracy of photometric estimation of defect size in radiation transmission direction, are developed

  9. Insights into the diurnal cycle of global Earth outgoing radiation using a numerical weather prediction model

    Science.gov (United States)

    Gristey, Jake J.; Chiu, J. Christine; Gurney, Robert J.; Morcrette, Cyril J.; Hill, Peter G.; Russell, Jacqueline E.; Brindley, Helen E.

    2018-04-01

    A globally complete, high temporal resolution and multiple-variable approach is employed to analyse the diurnal cycle of Earth's outgoing energy flows. This is made possible via the use of Met Office model output for September 2010 that is assessed alongside regional satellite observations throughout. Principal component analysis applied to the long-wave component of modelled outgoing radiation reveals dominant diurnal patterns related to land surface heating and convective cloud development, respectively explaining 68.5 and 16.0 % of the variance at the global scale. The total variance explained by these first two patterns is markedly less than previous regional estimates from observations, and this analysis suggests that around half of the difference relates to the lack of global coverage in the observations. The first pattern is strongly and simultaneously coupled to the land surface temperature diurnal variations. The second pattern is strongly coupled to the cloud water content and height diurnal variations, but lags the cloud variations by several hours. We suggest that the mechanism controlling the delay is a moistening of the upper troposphere due to the evaporation of anvil cloud. The short-wave component of modelled outgoing radiation, analysed in terms of albedo, exhibits a very dominant pattern explaining 88.4 % of the variance that is related to the angle of incoming solar radiation, and a second pattern explaining 6.7 % of the variance that is related to compensating effects from convective cloud development and marine stratocumulus cloud dissipation. Similar patterns are found in regional satellite observations, but with slightly different timings due to known model biases. The first pattern is controlled by changes in surface and cloud albedo, and Rayleigh and aerosol scattering. The second pattern is strongly coupled to the diurnal variations in both cloud water content and height in convective regions but only cloud water content in marine

  10. Global distributions of diurnal and semi-diurnal tides: observations from HRDI-UARS of the MLT region

    Directory of Open Access Journals (Sweden)

    A. H. Manson

    Full Text Available HRDI (High Resolution Doppler Interferometer-UARS winds data have been analyzed in 4° latitude by 10° longitude cells at 96 km to obtain global contour maps of solar-tidal amplitudes and phases, and also mean winds. The solstices June–July (1993, December–January (1993–1994, and one equinox September–October (1994 are shown. 

    The 24-h diurnal tide that maximizes near the 20–25° latitude has significant seasonal changes with equinoctial maxima, and very clear longitudinal variability. Maxima are very clear over the oceans. In contrast, the 12-h semi-diurnal tides that maximize near the 40–55° latitude have very strong seasonal changes with winter maxima, and more modest longitudinal changes. The similarities with MLT (mesosphere-lower thermosphere radar observations (90 km and the GSWM (Global Scale Wave Model are very satisfactory. The mean winds are consistent with expectations and show clear poleward flow from summer to winter hemispheres in the solstices.

    Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides Radio science (remote sensing

  11. Global distributions of diurnal and semi-diurnal tides: observations from HRDI-UARS of the MLT region

    Directory of Open Access Journals (Sweden)

    A. H. Manson

    2002-11-01

    Full Text Available HRDI (High Resolution Doppler Interferometer-UARS winds data have been analyzed in 4° latitude by 10° longitude cells at 96 km to obtain global contour maps of solar-tidal amplitudes and phases, and also mean winds. The solstices June–July (1993, December–January (1993–1994, and one equinox September–October (1994 are shown.  The 24-h diurnal tide that maximizes near the 20–25° latitude has significant seasonal changes with equinoctial maxima, and very clear longitudinal variability. Maxima are very clear over the oceans. In contrast, the 12-h semi-diurnal tides that maximize near the 40–55° latitude have very strong seasonal changes with winter maxima, and more modest longitudinal changes. The similarities with MLT (mesosphere-lower thermosphere radar observations (90 km and the GSWM (Global Scale Wave Model are very satisfactory. The mean winds are consistent with expectations and show clear poleward flow from summer to winter hemispheres in the solstices.Key words. Meteorology and atmospheric dynamics (middle atmosphere dynamics; waves and tides Radio science (remote sensing

  12. Modelling of diurnal cycle under climate change

    Energy Technology Data Exchange (ETDEWEB)

    Eliseev, A V; Bezmenov, K V; Demchenko, P F; Mokhov, I I; Petoukhov, V K [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Atmospheric Physics

    1996-12-31

    The observed diurnal temperature range (DTR) displays remarkable change during last 30 years. Land air DTR generally decreases under global climate warming due to more significant night minimum temperature increase in comparison with day maximum temperature increase. Atmosphere hydrological cycle characteristics change under global warming and possible background aerosol atmosphere content change may cause essential errors in the estimation of DTR tendencies of change under global warming. The result of this study is the investigation of cloudiness effect on the DTR and blackbody radiative emissivity diurnal range. It is shown that in some cases (particularly in cold seasons) it results in opposite change in DTR and BD at doubled CO{sub 2} atmosphere content. The influence of background aerosol is the same as the cloudiness one

  13. Modelling of diurnal cycle under climate change

    Energy Technology Data Exchange (ETDEWEB)

    Eliseev, A.V.; Bezmenov, K.V.; Demchenko, P.F.; Mokhov, I.I.; Petoukhov, V.K. [Russian Academy of Sciences, Moscow (Russian Federation). Inst. of Atmospheric Physics

    1995-12-31

    The observed diurnal temperature range (DTR) displays remarkable change during last 30 years. Land air DTR generally decreases under global climate warming due to more significant night minimum temperature increase in comparison with day maximum temperature increase. Atmosphere hydrological cycle characteristics change under global warming and possible background aerosol atmosphere content change may cause essential errors in the estimation of DTR tendencies of change under global warming. The result of this study is the investigation of cloudiness effect on the DTR and blackbody radiative emissivity diurnal range. It is shown that in some cases (particularly in cold seasons) it results in opposite change in DTR and BD at doubled CO{sub 2} atmosphere content. The influence of background aerosol is the same as the cloudiness one

  14. Photometric properties of type II supernovae

    Energy Technology Data Exchange (ETDEWEB)

    Barbon, R [Osservatorio Astrofisico, Asiago (Italy); Trieste Univ. (Italy). Instituto di Matematica); Ciatti, F; Rosino, L [Osservatorio Astrofisico, Asiago (Italy); Pavia Univ. (Italy))

    1979-02-01

    An analysis of the available photometric observations for type II supernovae is presented. The possibility of drawing average curves by the fitting method, as previously done for type I supernovae, is indicated. Two basic shapes have been put into evidence, the first one (2/3 of the objects) is characterized by the presence of a plateau at intermediate phase, the second one by an almost linear decline. Average curves have been also built for the intrinsic color indices. Peculiar cases are discussed, including the unusual objects of types III-IV. The mean absolute magnitude at maximum for type II supernovae has been determined about Msub(B) = -16.45 (sigma=0.78), as a calibration for their use as distance indicators. The distribution in different morphological types and luminosity classes of the parent galaxies is briefly discussed.

  15. Photometrical research geostationary satellite "SBIRS GEO-2"

    Science.gov (United States)

    Sukhov, P. P.; Epishev, V. P; Sukhov, K. P; Kudak, V. I.

    The multicolor photometrical observations GSS "Sbirs Geo-2" were carried in B,V,R filters out during the autumn equinox 2014 and spring 2015 y. Periodic appearance of many light curves and dips of mirror reflections suggests that the GSS was not in orbit in a static position, predetermined three-axis orientation and in dynamic motion. On the basis of computer modeling suggests the following dynamics GSS "Sbirs Geo-2" in orbit. Helically scanning the visible Earth's surface infrared satellite sensors come with period P1 = 15.66 sec. and the rocking of the GSS about the direction of the motion vector of the satellite in orbit with P2 = 62.64 sec., most likely with the purpose to survey the greatest possible portion of the earth's surface.

  16. Robust photometric stereo using structural light sources

    Science.gov (United States)

    Han, Tian-Qi; Cheng, Yue; Shen, Hui-Liang; Du, Xin

    2014-05-01

    We propose a robust photometric stereo method by using structural arrangement of light sources. In the arrangement, light sources are positioned on a planar grid and form a set of collinear combinations. The shadow pixels are detected by adaptive thresholding. The specular highlight and diffuse pixels are distinguished according to their intensity deviations of the collinear combinations, thanks to the special arrangement of light sources. The highlight detection problem is cast as a pattern classification problem and is solved using support vector machine classifiers. Considering the possible misclassification of highlight pixels, the ℓ1 regularization is further employed in normal map estimation. Experimental results on both synthetic and real-world scenes verify that the proposed method can robustly recover the surface normal maps in the case of heavy specular reflection and outperforms the state-of-the-art techniques.

  17. natalensis) and diurn'al (Rhabdomys pumilio)

    African Journals Online (AJOL)

    The thermo neutral zone for both speCies was found to be at T. = 32 ± 1 °e. Below the lower critical point. Vo. for the diurnal species (R. pumilio) was significantly higher. (p

  18. PHOTOMETRIC SUPERNOVA CLASSIFICATION WITH MACHINE LEARNING

    International Nuclear Information System (INIS)

    Lochner, Michelle; Peiris, Hiranya V.; Lahav, Ofer; Winter, Max K.; McEwen, Jason D.

    2016-01-01

    Automated photometric supernova classification has become an active area of research in recent years in light of current and upcoming imaging surveys such as the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope, given that spectroscopic confirmation of type for all supernovae discovered will be impossible. Here, we develop a multi-faceted classification pipeline, combining existing and new approaches. Our pipeline consists of two stages: extracting descriptive features from the light curves and classification using a machine learning algorithm. Our feature extraction methods vary from model-dependent techniques, namely SALT2 fits, to more independent techniques that fit parametric models to curves, to a completely model-independent wavelet approach. We cover a range of representative machine learning algorithms, including naive Bayes, k -nearest neighbors, support vector machines, artificial neural networks, and boosted decision trees (BDTs). We test the pipeline on simulated multi-band DES light curves from the Supernova Photometric Classification Challenge. Using the commonly used area under the curve (AUC) of the Receiver Operating Characteristic as a metric, we find that the SALT2 fits and the wavelet approach, with the BDTs algorithm, each achieve an AUC of 0.98, where 1 represents perfect classification. We find that a representative training set is essential for good classification, whatever the feature set or algorithm, with implications for spectroscopic follow-up. Importantly, we find that by using either the SALT2 or the wavelet feature sets with a BDT algorithm, accurate classification is possible purely from light curve data, without the need for any redshift information.

  19. PHOTOMETRIC SUPERNOVA CLASSIFICATION WITH MACHINE LEARNING

    Energy Technology Data Exchange (ETDEWEB)

    Lochner, Michelle; Peiris, Hiranya V.; Lahav, Ofer; Winter, Max K. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom); McEwen, Jason D., E-mail: dr.michelle.lochner@gmail.com [Mullard Space Science Laboratory, University College London, Surrey RH5 6NT (United Kingdom)

    2016-08-01

    Automated photometric supernova classification has become an active area of research in recent years in light of current and upcoming imaging surveys such as the Dark Energy Survey (DES) and the Large Synoptic Survey Telescope, given that spectroscopic confirmation of type for all supernovae discovered will be impossible. Here, we develop a multi-faceted classification pipeline, combining existing and new approaches. Our pipeline consists of two stages: extracting descriptive features from the light curves and classification using a machine learning algorithm. Our feature extraction methods vary from model-dependent techniques, namely SALT2 fits, to more independent techniques that fit parametric models to curves, to a completely model-independent wavelet approach. We cover a range of representative machine learning algorithms, including naive Bayes, k -nearest neighbors, support vector machines, artificial neural networks, and boosted decision trees (BDTs). We test the pipeline on simulated multi-band DES light curves from the Supernova Photometric Classification Challenge. Using the commonly used area under the curve (AUC) of the Receiver Operating Characteristic as a metric, we find that the SALT2 fits and the wavelet approach, with the BDTs algorithm, each achieve an AUC of 0.98, where 1 represents perfect classification. We find that a representative training set is essential for good classification, whatever the feature set or algorithm, with implications for spectroscopic follow-up. Importantly, we find that by using either the SALT2 or the wavelet feature sets with a BDT algorithm, accurate classification is possible purely from light curve data, without the need for any redshift information.

  20. Evaluation of NASA GEOS-ADAS Modeled Diurnal Warming Through Comparisons to SEVIRI and AMSR2 SST Observations

    Science.gov (United States)

    Gentemann, C. L.; Akella, S.

    2018-02-01

    An analysis of the ocean skin Sea Surface Temperature (SST) has been included in the Goddard Earth Observing System (GEOS) - Atmospheric Data Assimilation System (ADAS), Version 5 (GEOS-ADAS). This analysis is based on the GEOS atmospheric general circulation model (AGCM) that simulates near-surface diurnal warming and cool skin effects. Analysis for the skin SST is performed along with the atmospheric state, including Advanced Very High Resolution Radiometer (AVHRR) satellite radiance observations as part of the data assimilation system. One month (September, 2015) of GEOS-ADAS SSTs were compared to collocated satellite Spinning Enhanced Visible and InfraRed Imager (SEVIRI) and Advanced Microwave Scanning Radiometer 2 (AMSR2) SSTs to examine how the GEOS-ADAS diurnal warming compares to the satellite measured warming. The spatial distribution of warming compares well to the satellite observed distributions. Specific diurnal events are analyzed to examine variability within a single day. The dependence of diurnal warming on wind speed, time of day, and daily average insolation is also examined. Overall the magnitude of GEOS-ADAS warming is similar to the warming inferred from satellite retrievals, but several weaknesses in the GEOS-AGCM simulated diurnal warming are identified and directly related back to specific features in the formulation of the diurnal warming model.

  1. THE APPARATUS FOR ALIGNMENT OF THE PHOTOMETRIC LAMP FILAMENT

    Directory of Open Access Journals (Sweden)

    V. A. Dlugunovich

    2015-01-01

    Full Text Available During photometric measurements involving the use of photometric lamps it is necessary that the filament of lamp takes a strictly predetermined position with respect to the photodetector and the optical axis of the photometric setup. The errors in positioning of alignment filament with respect to the optical axis of the measuring system lead to increase the uncertainty of measurement of the photometric characteristics of the light sources. A typical method for alignment of filament of photometric lamps is based on the use a diopter tubes (telescopes. Using this method, the mounting of filament to the required position is carried out by successive approximations, which requires special concentration and a lot of time. The aim of this work is to develop an apparatus for alignment which allows simultaneous alignment of the filament of lamps in two mutually perpendicular planes. The method and apparatus for alignment of the photometric lamp filament during measurements of the photometric characteristics of light sources based on two digital video cameras is described in this paper. The apparatus allows to simultaneously displaying the image of lamps filament on the computer screen in two mutually perpendicular planes. The apparatus eliminates a large number of functional units requiring elementwise alignment and reduces the time required to carry out the alignment. The apparatus also provides the imaging of lamps filament with opaque coated on the bulb. The apparatus is used at the National standard of light intensity and illuminance units of the Republic of Belarus. 

  2. Magnetic cycles and rotation periods of late-type stars from photometric time series

    Science.gov (United States)

    Suárez Mascareño, A.; Rebolo, R.; González Hernández, J. I.

    2016-10-01

    Aims: We investigate the photometric modulation induced by magnetic activity cycles and study the relationship between rotation period and activity cycle(s) in late-type (FGKM) stars. Methods: We analysed light curves, spanning up to nine years, of 125 nearby stars provided by the All Sky Automated Survey (ASAS). The sample is mainly composed of low-activity, main-sequence late-A to mid-M-type stars. We performed a search for short (days) and long-term (years) periodic variations in the photometry. We modelled the light curves with combinations of sinusoids to measure the properties of these periodic signals. To provide a better statistical interpretation of our results, we complement our new results with results from previous similar works. Results: We have been able to measure long-term photometric cycles of 47 stars, out of which 39 have been derived with false alarm probabilities (FAP) of less than 0.1 per cent. Rotational modulation was also detected and rotational periods were measured in 36 stars. For 28 stars we have simultaneous measurements of activity cycles and rotational periods, 17 of which are M-type stars. We measured both photometric amplitudes and periods from sinusoidal fits. The measured cycle periods range from 2 to 14 yr with photometric amplitudes in the range of 5-20 mmag. We found that the distribution of cycle lengths for the different spectral types is similar, as the mean cycle is 9.5 yr for F-type stars, 6.7 yr for G-type stars, 8.5 yr for K-type stars, 6.0 yr for early M-type stars, and 7.1 yr for mid-M-type stars. On the other hand, the distribution of rotation periods is completely different, trending to longer periods for later type stars, from a mean rotation of 8.6 days for F-type stars to 85.4 days in mid-M-type stars. The amplitudes induced by magnetic cycles and rotation show a clear correlation. A trend of photometric amplitudes with rotation period is also outlined in the data. The amplitudes of the photometric variability

  3. Studying Diurnal Variations of Aerosols with NASA MERRA-2 Reanalysis Data

    Science.gov (United States)

    Shen, Suhung; Ostrenga, Dana M.; Zeng, Jian; Vollmer, Bruce E.

    2018-01-01

    Aerosols play an important role in atmospheric dynamics, climate variations, and Earth's energy cycle by altering the radiation balance in the atmosphere through interaction with clouds, providing fertilizer for forests and canopy, and as a supply of iron to the ocean over long time periods. Studies suggest that much of the feedback between dust aerosols and dynamics is associated with diurnal and synoptic scale variability. However, the lack of sub-daily resolution of aerosols from satellite observations makes it difficult to study the diurnal characteristics, especially over tropical and subtropical regions. Investigation of this topic utilizes over 37 years of simulated global aerosol products from NASA atmospheric reanalysis, in the second Modern-Era Retrospective analysis for Research and Applications (MERRA-2) data set, available from NASA Goddard Earth Science Data and Information Services Center (GES DISC). MERRA-2 covers the period 1980-present, and is continuing as an ongoing climate analysis. Aerosol assimilation is included throughout the period, using data from MODIS, MISR, AERONET, and AVHRR (in the pre-EOS period). The aerosols are assimilated using the MERRA-2 aerosol model, which interacts directly with radiation parameterization, and is radiatively coupled with atmospheric model dynamics in the Goddard Earth Observing System Model, Version 5 (GEOS-5). Hourly, monthly, and monthly diurnal data are available at spatial resolution of 0.5o x 0.625o (latitude x longitude). By using MERRA-2 hourly and monthly diurnal products, different aerosol diurnal variabilities are observed over North America, Africa, Asia, and Australia, that may be due to different meteorological conditions and aerosol sources. The presentation will also provide an overview of MERRA-2 data services at GES DISC, such as how to find and download data, and how to quickly visualize and analyze data online with Giovanni.

  4. Application of the Trend Filtering Algorithm for Photometric Time Series Data

    Science.gov (United States)

    Gopalan, Giri; Plavchan, Peter; van Eyken, Julian; Ciardi, David; von Braun, Kaspar; Kane, Stephen R.

    2016-08-01

    Detecting transient light curves (e.g., transiting planets) requires high-precision data, and thus it is important to effectively filter systematic trends affecting ground-based wide-field surveys. We apply an implementation of the Trend Filtering Algorithm (TFA) to the 2MASS calibration catalog and select Palomar Transient Factory (PTF) photometric time series data. TFA is successful at reducing the overall dispersion of light curves, however, it may over-filter intrinsic variables and increase “instantaneous” dispersion when a template set is not judiciously chosen. In an attempt to rectify these issues we modify the original TFA from the literature by including measurement uncertainties in its computation, including ancillary data correlated with noise, and algorithmically selecting a template set using clustering algorithms as suggested by various authors. This approach may be particularly useful for appropriately accounting for variable photometric precision surveys and/or combined data sets. In summary, our contributions are to provide a MATLAB software implementation of TFA and a number of modifications tested on synthetics and real data, summarize the performance of TFA and various modifications on real ground-based data sets (2MASS and PTF), and assess the efficacy of TFA and modifications using synthetic light curve tests consisting of transiting and sinusoidal variables. While the transiting variables test indicates that these modifications confer no advantage to transit detection, the sinusoidal variables test indicates potential improvements in detection accuracy.

  5. Photometric studies of δ Scuti stars. I. IP Virginis

    Science.gov (United States)

    Joner, Michael D.; Hintz, Eric G.; Collier, Matthew W.

    1998-01-01

    We report 15 new times of maximum light for the δ Scuti star IP Virginis (formerly known as SA 106‐1024). An analysis of all times of maximum light indicates that IP Vir has been decreasing in period at a constant rate of − days day−1. Evidence is also presented that IP Vir is a double‐mode variable with a period ratio of . This period ratio predicts a [Fe/H] value of −0.3. From photometric (uvbyβ) observations, we find a foreground reddening of .008 mag and a metallicity of [Fe/H] = +0.05. It is shown that [Fe/H] = −0.3 is most likely the correct value. Intrinsic ‐ and c1‐values, plotted in a model atmosphere grid, indicate a mean effective temperature, K, and a mean surface gravity, . All of these physical parameters support Landolt's initial conclusion that IP Vir is an ordinary δ Sct star.

  6. Covariability in the Monthly Mean Convective and Radiative Diurnal Cycles in the Amazon

    Science.gov (United States)

    Dodson, Jason B.; Taylor, Patrick C.

    2015-01-01

    The diurnal cycle of convective clouds greatly influences the radiative energy balance in convectively active regions of Earth, through both direct presence, and the production of anvil and stratiform clouds. Previous studies show that the frequency and properties of convective clouds can vary on monthly timescales as a result of variability in the monthly mean atmospheric state. Furthermore, the radiative budget in convectively active regions also varies by up to 7 Wm-2 in convectively active regions. These facts suggest that convective clouds connect atmospheric state variability and radiation variability beyond clear sky effects alone. Previous research has identified monthly covariability between the diurnal cycle of CERES-observed top-of-atmosphere radiative fluxes and multiple atmospheric state variables from reanalysis over the Amazon region. ASVs that enhance (reduce) deep convection, such as CAPE (LTS), tend to shift the daily OLR and cloud albedo maxima earlier (later) in the day by 2-3 hr. We first test the analysis method using multiple reanalysis products for both the dry and wet seasons to further investigate the robustness of the preliminary results. We then use CloudSat data as an independent cloud observing system to further evaluate the relationships of cloud properties to variability in radiation and atmospheric states. While CERES can decompose OLR variability into clear sky and cloud effects, it cannot determine what variability in cloud properties lead to variability in the radiative cloud effects. Cloud frequency, cloud top height, and cloud microphysics all contribute to the cloud radiative effect, all of which are observable by CloudSat. In addition, CloudSat can also observe the presence and variability of deep convective cores responsible for the production of anvil clouds. We use these capabilities to determine the covariability of convective cloud properties and the radiative diurnal cycle.

  7. Annual and diurnal african biomass burning temporal dynamics

    Directory of Open Access Journals (Sweden)

    G. Roberts

    2009-05-01

    Full Text Available Africa is the single largest continental source of biomass burning emissions. Here we conduct the first analysis of one full year of geostationary active fire detections and fire radiative power data recorded over Africa at 15-min temporal interval and a 3 km sub-satellite spatial resolution by the Spinning Enhanced Visible and Infrared Imager (SEVIRI imaging radiometer onboard the Meteosat-8 satellite. We use these data to provide new insights into the rates and totals of open biomass burning over Africa, particularly into the extremely strong seasonal and diurnal cycles that exist across the continent. We estimate peak daily biomass combustion totals to be 9 and 6 million tonnes of fuel per day in the northern and southern hemispheres respectively, and total fuel consumption between February 2004 and January 2005 is estimated to be at least 855 million tonnes. Analysis is carried out with regard to fire pixel temporal persistence, and we note that the majority of African fires are detected only once in consecutive 15 min imaging slots. An investigation of the variability of the diurnal fire cycle is carried out with respect to 20 different land cover types, and whilst differences are noted between land covers, the fire diurnal cycle characteristics for most land cover type are very similar in both African hemispheres. We compare the Fire Radiative Power (FRP derived biomass combustion estimates to burned-areas, both at the scale of individual fires and over the entire continent at a 1-degree scale. Fuel consumption estimates are found to be less than 2 kg/m2 for all land cover types noted to be subject to significant fire activity, and for savanna grasslands where literature values are commonly reported the FRP-derived median fuel consumption estimate of 300 g/m2 is well within commonly quoted values. Meteosat-derived FRP data of the type presented here is now available freely to interested users continuously and in near

  8. Daily diurnal variation in admissions for ruptured abdominal aortic aneurysms.

    LENUS (Irish Health Repository)

    Killeen, Shane

    2012-02-03

    BACKGROUND: Many vascular events, such as myocardial infarction and cerebrovascular accident, demonstrate a circadian pattern of presentation. Blood pressure is intimately related to these pathologies and is the one physiological variable consistently associated with abdominal aortic aneurysm rupture. It also demonstrates a diurnal variation. The purpose of this study was to determine if rupture of an abdominal aortic aneurysm (RAAA) exhibits a diurnal variation. METHODS: A retrospective cohort-based study was performed to determine the timing of presentation of RAAA to the vascular unit of Cork University Hospital over a 15-year period. Time of admission, symptom onset, and co-morbidities such as hypertension were noted. Fournier\\'s analysis and chi-squared analysis were performed. To ameliorate possible confounding factors, patients admitted with perforated peptic ulcers were examined in the same manner. RESULTS: A total of 148 cases of RAAA were identified, with a male preponderance (71.7% [124] male versus 29.3% [44] female patients) and a mean age of 74.4 +\\/- 7.2 years at presentation. 70.9% (105) were known to have hypertension, 52.2% (77) were current smokers, and 46.8% (69) were being treated for chronic obstructive airway disease (COAD). Time of symptom onset was recorded in 88.5% (131) of patients. There was a marked early morning peak in RAAA admissions, with the highest number of RAAA being admitted between 08.00 and 09.59. A second, smaller peak was observed at 14.00-15.59. These findings were suggestive of diurnal variation. [chi(2) =16.75, p < 0.003]. Some 40% (59) of patients were admitted between 00.00 and 06.00, an incidence significantly higher than for other time periods (06.00-12.00, 12.00-18.00, and 18.00-24.00) [chi(2) = 18.72; df = 3; p < 0.0003]. A significantly higher number of patients admitted between 00.00 and 06.00 were known hypertensives (chi(2) = 7.94; p < 0.05). CONCLUSIONS: The findings of this study suggest a distinct

  9. Photometric Analysis and Period Investigation of the EW Type ...

    Indian Academy of Sciences (India)

    Photometric Analysis and Period Investigation of the EW Type. Eclipsing ... binary with the less massive secondary component filling the inner Roche lobe. ..... Cox 2000) assuming that the primary component is a normal main sequence star.

  10. Photometric immersion refractometry of bacterial spores.

    Science.gov (United States)

    Gerhardt, P; Beaman, T C; Corner, T R; Greenamyre, J T; Tisa, L S

    1982-01-01

    Photometric immersion refractometry was used to determine the average apparent refractive index (n) of five types of dormant Bacillus spores representing a 600-fold range in moist-heat resistance determined as a D100 value. The n of a spore type increased as the molecular size of various immersion solutes decreased. For comparison of the spore types, the n of the entire spore and of the isolated integument was determined by use of bovine serum albumin, which is excluded from permeating into them. The n of the sporoplast (the structures bounded by the outer pericortex membrane) was determined by use of glucose, which was shown to permeate into the spore only as deeply as the pericortex membrane. Among the various spore types, an exponential increase in the heat resistance correlated with the n of the entire spore and of the sporoplast, but not of the isolated perisporoplast integument. Correlation of the n with the solids content of the entire spore provided a method of experimentally obtaining the refractive index increment (dn/dc), which was constant for the various spore types and enables the calculation of solids and water content from an n. Altogether, the results showed that the total water content is distributed unequally within the dormant spore, with less water in the sporoplast than in the perisporoplast integument, and that the sporoplast becomes more refractile and therefore more dehydrated as the heat resistance becomes greater among the various spore types. PMID:6802796

  11. Photometric stability of the lunar surface

    Science.gov (United States)

    Kieffer, H.H.

    1997-01-01

    The rate at which cratering events currently occur on the Moon is considered in light of their influence on the use of the Moon as a radiometric standard. The radiometric effect of small impact events is determined empirically from the study of Clementine images. Events that would change the integral brightness of the moon by 1% are expected once per 1.4 Gyr. Events that cause a 1% shift in one pixel for low Earth-orbiting instruments with a 1-km nadir field of view are expected approximately once each 43 Myr. Events discernible at 1% radiometric resolution with a 5 arc-sec telescope resolution correspond to crater diameters of approximately 210 m and are expected once every 200 years. These rates are uncertain by a factor of two. For a fixed illumination and observation geometry, the Moon can be considered photometrically stable to 1 ?? 10-8per annum for irradiance, and 1 ?? 10-7per annum for radiance at a resolution common for spacecraft imaging instruments, exceeding reasonable instrument goals by six orders of magnitude. ?? 1997 Academic Press.

  12. Photometric Detection of Extra-Solar Planets

    Science.gov (United States)

    Hatzes, Artie P.; Cochran, William D.

    2004-01-01

    This NASA Origins Program grant supported the TEMPEST Texas McDonald Photometric Extrasolar Search for Transits) program at McDonald Observatory, which searches for transits of extrasolar planets across the disks of their parent stars. The basic approach is to use a wide-field ground-based telescope (in our case the McDonald Observatory 0.76m telescope and it s Prime Focus Corrector) to search for transits of short period (1-15 day orbits) of close-in hot-Jupiter planets in orbit around a large sample of field stars. The next task is to search these data streams for possible transit events. We collected our first set of test data for this program using the 0.76 m PFC in the summer of 1998. From those data, we developed the optimal observing procedures, including tailoring the stellar density, exposure times, and filters to best-suit the instrument and project. In the summer of 1999, we obtained the first partial season of data on a dedicated field in the constellation Cygnus. These data were used to develop and refine the reduction and analysis procedures to produce high-precision photometry and search for transits in the resulting light curves. The TeMPEST project subsequently obtained three full seasons of data on six different fields using the McDonald Observatory 0.76m PFC.

  13. Photometric determination of traces of metals

    International Nuclear Information System (INIS)

    Onishi, H.

    1986-01-01

    The first three editions of this widely used classic were published under the title Colorimetric Determination of Traces of Metals, with E.B. Sandell as author. Part I (General Aspects) of the fourth edition was co-authored by E.B. Sandell and H. Onishi and published in 1978. After Sandell's death in 1984, Onishi assumed the monumental task of revising Part II. This book (Part IIA) consists of 21 chapters in which the photometric determinations of the individual metals, aluminium to lithium (including the lanthanoids), are described. Each chapter is divided into three sections: Separations, Methods of Determination, and Applications. The sections on Separations are of general interest and include methods based on precipitation, ion-exchange, chromatography, and liquid-liquid extraction. Molecular absorption and fluorescence techniques are described in the sections on determinations, and the emphasis is on the use of well-established reagents. Several reagents that have been recently introduced for the determination of trace levels of metals are also critically reviewed at the end of each section on methods of determination. Important applications of these methods to the determination of trace metals in complex organic and inorganic materials are described in detail at the end of each chapter

  14. Empirical photometric calibration of the Gaia red clump: Colours, effective temperature, and absolute magnitude

    Science.gov (United States)

    Ruiz-Dern, L.; Babusiaux, C.; Arenou, F.; Turon, C.; Lallement, R.

    2018-01-01

    Context. Gaia Data Release 1 allows the recalibration of standard candles such as the red clump stars. To use those stars, they first need to be accurately characterised. In particular, colours are needed to derive interstellar extinction. As no filter is available for the first Gaia data release and to avoid the atmosphere model mismatch, an empirical calibration is unavoidable. Aims: The purpose of this work is to provide the first complete and robust photometric empirical calibration of the Gaia red clump stars of the solar neighbourhood through colour-colour, effective temperature-colour, and absolute magnitude-colour relations from the Gaia, Johnson, 2MASS, HIPPARCOS, Tycho-2, APASS-SLOAN, and WISE photometric systems, and the APOGEE DR13 spectroscopic temperatures. Methods: We used a 3D extinction map to select low reddening red giants. To calibrate the colour-colour and the effective temperature-colour relations, we developed a MCMC method that accounts for all variable uncertainties and selects the best model for each photometric relation. We estimated the red clump absolute magnitude through the mode of a kernel-based distribution function. Results: We provide 20 colour versus G-Ks relations and the first Teff versus G-Ks calibration. We obtained the red clump absolute magnitudes for 15 photometric bands with, in particular, MKs = (-1.606 ± 0.009) and MG = (0.495 ± 0.009) + (1.121 ± 0.128)(G-Ks-2.1). We present a dereddened Gaia-TGAS HR diagram and use the calibrations to compare its red clump and its red giant branch bump with Padova isochrones. Full Table A.1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/609/A116

  15. Photometric Compliance of Tablet Screens and Retro-Illuminated Acuity Charts As Visual Acuity Measurement Devices.

    Science.gov (United States)

    Livingstone, I A T; Tarbert, C M; Giardini, M E; Bastawrous, A; Middleton, D; Hamilton, R

    2016-01-01

    Mobile technology is increasingly used to measure visual acuity. Standards for chart-based acuity tests specify photometric requirements for luminance, optotype contrast and luminance uniformity. Manufacturers provide some photometric data but little is known about tablet performance for visual acuity testing. This study photometrically characterised seven tablet computers (iPad, Apple inc.) and three ETDRS (Early Treatment Diabetic Retinopathy Study) visual acuity charts with room lights on and off, and compared findings with visual acuity measurement standards. Tablet screen luminance and contrast were measured using nine points across a black and white checkerboard test screen at five arbitrary brightness levels. ETDRS optotypes and adjacent white background luminance and contrast were measured. All seven tablets (room lights off) exceeded the most stringent requirement for mean luminance (≥ 120 cd/m2) providing the nominal brightness setting was above 50%. All exceeded contrast requirement (Weber ≥ 90%) regardless of brightness setting, and five were marginally below the required luminance uniformity threshold (Lmin/Lmax ≥ 80%). Re-assessing three tablets with room lights on made little difference to mean luminance or contrast, and improved luminance uniformity to exceed the threshold. The three EDTRS charts (room lights off) had adequate mean luminance (≥ 120 cd/m2) and Weber contrast (≥ 90%), but all three charts failed to meet the luminance uniformity standard (Lmin/Lmax ≥ 80%). Two charts were operating beyond manufacturer's recommended lamp replacement schedule. With room lights on, chart mean luminance and Weber contrast increased, but two charts still had inadequate luminance uniformity. Tablet computers showed less inter-device variability, higher contrast, and better luminance uniformity than charts in both lights-on and lights-off environments, providing brightness setting was >50%. Overall, iPad tablets matched or marginally out

  16. Photometric Compliance of Tablet Screens and Retro-Illuminated Acuity Charts As Visual Acuity Measurement Devices.

    Directory of Open Access Journals (Sweden)

    I A T Livingstone

    Full Text Available Mobile technology is increasingly used to measure visual acuity. Standards for chart-based acuity tests specify photometric requirements for luminance, optotype contrast and luminance uniformity. Manufacturers provide some photometric data but little is known about tablet performance for visual acuity testing. This study photometrically characterised seven tablet computers (iPad, Apple inc. and three ETDRS (Early Treatment Diabetic Retinopathy Study visual acuity charts with room lights on and off, and compared findings with visual acuity measurement standards. Tablet screen luminance and contrast were measured using nine points across a black and white checkerboard test screen at five arbitrary brightness levels. ETDRS optotypes and adjacent white background luminance and contrast were measured. All seven tablets (room lights off exceeded the most stringent requirement for mean luminance (≥ 120 cd/m2 providing the nominal brightness setting was above 50%. All exceeded contrast requirement (Weber ≥ 90% regardless of brightness setting, and five were marginally below the required luminance uniformity threshold (Lmin/Lmax ≥ 80%. Re-assessing three tablets with room lights on made little difference to mean luminance or contrast, and improved luminance uniformity to exceed the threshold. The three EDTRS charts (room lights off had adequate mean luminance (≥ 120 cd/m2 and Weber contrast (≥ 90%, but all three charts failed to meet the luminance uniformity standard (Lmin/Lmax ≥ 80%. Two charts were operating beyond manufacturer's recommended lamp replacement schedule. With room lights on, chart mean luminance and Weber contrast increased, but two charts still had inadequate luminance uniformity. Tablet computers showed less inter-device variability, higher contrast, and better luminance uniformity than charts in both lights-on and lights-off environments, providing brightness setting was >50%. Overall, iPad tablets matched or marginally out

  17. Measuring redshift-space distortions using photometric surveys

    OpenAIRE

    Ross, Ashley; Percival, Will; Crocce, M.; Cabre, A.; Gaztanaga, E.

    2011-01-01

    We outline how redshift-space distortions (RSD) can be measured from the angular correlation function w({\\theta}), of galaxies selected from photometric surveys. The natural degeneracy between RSD and galaxy bias can be minimized by comparing results from bins with top-hat galaxy selection in redshift, and bins based on the radial position of galaxy pair centres. This comparison can also be used to test the accuracy of the photometric redshifts. The presence of RSD will be clearly detectable ...

  18. Intensity measurement of automotive headlamps using a photometric vision system

    Science.gov (United States)

    Patel, Balvant; Cruz, Jose; Perry, David L.; Himebaugh, Frederic G.

    1996-01-01

    Requirements for automotive head lamp luminous intensity tests are introduced. The rationale for developing a non-goniometric photometric test system is discussed. The design of the Ford photometric vision system (FPVS) is presented, including hardware, software, calibration, and system use. Directional intensity plots and regulatory test results obtained from the system are compared to corresponding results obtained from a Ford goniometric test system. Sources of error for the vision system and goniometer are discussed. Directions for new work are identified.

  19. Diurnal and seasonal occurrence of polar patches

    Directory of Open Access Journals (Sweden)

    A. S. Rodger

    1996-05-01

    Full Text Available Analysis of the diurnal and seasonal variation of polar patches, as identified in two years of HF-radar data from Halley, Antarctica during a period near sunspot maximum, shows that there is a broad maximum in occurrence centred about magnetic noon, not local noon. There are minima in occurrence near midsummer and midwinter, with maxima in occurrence between equinox and winter. There are no significant correlations between the occurrence of polar patches and the corresponding hourly averages of the solar wind and IMF parameters, except that patches usually occur when the interplanetary magnetic field has a southward component. The results can be understood in terms of UT and seasonal differences in the plasma concentration being convected from the dayside ionosphere into the polar cap. In summer and winter the electron concentrations in the polar cap are high and low, respectively, but relatively unstructured. About equinox, a tongue of enhanced ionisation is convected into the polar cap; this tongue is then structured by the effects of the interplanetary magnetic field, but these Halley data cannot be used to separate the various competing mechanisms for patch formation. The observed diurnal and seasonal variation in the occurrence of polar patches are largely consistent with predictions of Sojka et al. (1994 when their results are translated into the southern hemisphere. However, the ionospheric effects of flux transfer events are still considered essential in their formation, a feature not yet included in the Sojka et al. model.

  20. Deregulated power prices: comparison of diurnal patterns

    International Nuclear Information System (INIS)

    Ying Li; Flynn, P.C.

    2004-01-01

    We examine electrical power price, and in particular its daily and average weekday vs. weekend pattern of change, for 14 deregulated markets. Power price in deregulated markets shows fundamentally different patterns. North American markets show a monotonic diurnal weekday price pattern, while all other markets studied show more than one price peak. Deregulated power markets differ in maximum vs. minimum daily average price and in average weekday to weekend price, in turn creating a different incentive for a consumer to time shift power consuming activities. Markets differ in the extent to which a small fraction of the days shapes the average diurnal pattern and value of price. Deregulated markets show a wide variation in the correlation between load and price. Some deregulated markets, most notably Britain and Spain, show patterns that are predictable and consistent, and hence that can encourage a customer to shape consumption behaviors. Other markets, for example South Australia, have patterns that are inconsistent and irregular, and hence are hard for a customer to interpret; a customer in such a market will have a higher incentive to escape risk through hedging mechanisms. (Author)

  1. Deregulated power prices: comparison of diurnal patterns

    International Nuclear Information System (INIS)

    Li Ying; Flynn, Peter C.

    2004-01-01

    We examine electrical power price, and in particular its daily and average weekday vs. weekend pattern of change, for 14 deregulated markets. Power price in deregulated markets shows fundamentally different patterns. North American markets show a monotonic diurnal weekday price pattern, while all other markets studied show more than one price peak. Deregulated power markets differ in maximum vs. minimum daily average price and in average weekday to weekend price, in turn creating a different incentive for a consumer to time shift power consuming activities. Markets differ in the extent to which a small fraction of the days shapes the average diurnal pattern and value of price. Deregulated markets show a wide variation in the correlation between load and price. Some deregulated markets, most notably Britain and Spain, show patterns that are predictable and consistent, and hence that can encourage a customer to shape consumption behaviors. Other markets, for example South Australia, have patterns that are inconsistent and irregular, and hence are hard for a customer to interpret; a customer in such a market will have a higher incentive to escape risk through hedging mechanisms

  2. Concurrent and longitudinal associations between diurnal cortisol and body mass index across adolescence.

    Science.gov (United States)

    Ruttle, Paula L; Javaras, Kristin N; Klein, Marjorie H; Armstrong, Jeffrey M; Burk, Linnea R; Essex, Marilyn J

    2013-06-01

    Childhood and adolescent obesity have reached epidemic levels; however, little is known about the psychobiological underpinnings of obesity in youth and whether these differ from the mechanisms identified in adults. The current study examines concurrent (i.e., measured at the same point in time) and longitudinal (i.e., using earlier cortisol measures to predict later body mass index [BMI]) associations between diurnal cortisol and BMI across adolescence. Adolescent diurnal cortisol was measured over 3 days at each 11, 13, and 15 years. Hierarchical linear modeling was used to extract average measures of predicted morning, afternoon, evening levels of cortisol and the diurnal slope at each assessment. Adolescent BMI (kg/m(2)) was measured at 11, 13, 15, and 18 years. Sex, family socioeconomic status, mother's BMI, pubertal status, and adolescent mental health were examined as possible confounding variables. Linear regressions revealed that blunted patterns of adolescent cortisol were associated with increased measures of BMI across adolescence both concurrently and longitudinally, particularly when examining measures of cortisol in early adolescence. Multinomial logistic regressions extended the linear regression findings beyond BMI scores to encompass categories of obesity. The current study builds on previous research documenting diurnal cortisol-obesity findings in adults by demonstrating similar findings exist both concurrently and longitudinally in adolescents. Findings suggest the association between cortisol and BMI is developmentally influenced and that blunted diurnal cortisol patterns can be identified in overweight individuals at a younger age than previously thought. Copyright © 2013 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.

  3. Combined diurnal variations of discharge and hydrochemistry of the Isunnguata Sermia outlet, Greenland Ice Sheet

    Science.gov (United States)

    Graly, Joseph; Harrington, Joel; Humphrey, Neil

    2017-05-01

    In order to examine daily cycles in meltwater routing and storage in the Isunnguata Sermia outlet of the Greenland Ice Sheet, variations in outlet stream discharge and in major element hydrochemistry were assessed over a 6-day period in July 2013. Over 4 days, discharge was assessed from hourly photography of the outlet from multiple vantages, including where midstream naled ice provided a natural gauge. pH, electrical conductivity, suspended sediment, and major element and anion chemistry were measured in samples of stream water collected every 3 h.Photography and stream observations reveal that although river width and stage have only slight diurnal variation, there are large diurnal changes in discharge shown by the doubling in width of what we term the active channel, which is characterized by large standing waves and fast flow. The concentration of dissolved solutes follows a sinusoidal diurnal cycle, except for large and variable increases in dissolved solutes during the stream's waning flow. Solute concentrations vary by ˜ 30 % between diurnal minima and maxima. Discharge maxima and minima lag temperature and surface melt by 3-7 h; diurnal solute concentration minima and maxima lag discharge by 3-6 h.This phase shift between discharge and solute concentration suggests that during high flow, water is either encountering more rock material or is stored in longer contact with rock material. We suggest that expansion of a distributed subglacial hydrologic network into seldom accessed regions during high flow could account for these phenomena, and for a spike of partial silicate reaction products during waning flow, which itself suggests a pressure threshold-triggered release of stored water.

  4. Influence of observed diurnal cycles of aerosol optical depth on aerosol direct radiative effect

    Directory of Open Access Journals (Sweden)

    A. Arola

    2013-08-01

    Full Text Available The diurnal variability of aerosol optical depth (AOD can be significant, depending on location and dominant aerosol type. However, these diurnal cycles have rarely been taken into account in measurement-based estimates of aerosol direct radiative forcing (ADRF or aerosol direct radiative effect (ADRE. The objective of our study was to estimate the influence of diurnal aerosol variability at the top of the atmosphere ADRE estimates. By including all the possible AERONET sites, we wanted to assess the influence on global ADRE estimates. While focusing also in more detail on some selected sites of strongest impact, our goal was to also see the possible impact regionally. We calculated ADRE with different assumptions about the daily AOD variability: taking the observed daily AOD cycle into account and assuming diurnally constant AOD. Moreover, we estimated the corresponding differences in ADREs, if the single AOD value for the daily mean was taken from the the Moderate Resolution Imaging Spectroradiometer (MODIS Terra or Aqua overpass times, instead of accounting for the true observed daily variability. The mean impact of diurnal AOD variability on 24 h ADRE estimates, averaged over all AERONET sites, was rather small and it was relatively small even for the cases when AOD was chosen to correspond to the Terra or Aqua overpass time. This was true on average over all AERONET sites, while clearly there can be much stronger impact in individual sites. Examples of some selected sites demonstrated that the strongest observed AOD variability (the strongest morning afternoon contrast does not typically result in a significant impact on 24 h ADRE. In those cases, the morning and afternoon AOD patterns are opposite and thus the impact on 24 h ADRE, when integrated over all solar zenith angles, is reduced. The most significant effect on daily ADRE was induced by AOD cycles with either maximum or minimum AOD close to local noon. In these cases, the impact on

  5. Radial frequency diagram (sunflower) for the analysis of diurnal cycle parameters: Solar energy application

    International Nuclear Information System (INIS)

    Božnar, Marija Zlata; Grašič, Boštjan; Mlakar, Primož; Soares, Jacyra; Pereira de Oliveira, Amauri; Costa, Tássio Santos

    2015-01-01

    Graphical abstract: A new type of graphical presentation showing diurnal cycle of solar energy forecast. The application is possible for other parameters related to weather and green energy production. - Highlights: • The diurnal cycle of solar energy is important for the management of the electrical grid. • A solar plant’s average production depends on the statistical features of solar radiation. • The new tool – the “sunflower”, is proposed for solar energy availability representation. • The sunflower identifies and quantifies information with a clear diurnal cycle. • The sunflower diagram has been developed from the “wind rose” diagram. - Abstract: Many meteorological parameters present a natural diurnal cycle because they are directly or indirectly dependent on sunshine exposure. The solar radiation diurnal pattern is important to energy production, agriculture, prognostic models, health and general climatology. This article aims at introducing a new type of radial frequency diagram – hereafter called sunflower – for the analysis of solar radiation data in connection with energy production and also for climatological studies. The diagram is based on two-dimensional data sorting. Firstly data are sorted into classes representing hours in a day. Then the data in each hourly class is sorted into classes of the observed variable values. The relative frequencies of the value classes are shown as sections on each hour’s segment in a radial diagram. The radial diagram forms a unique pattern for each analysed dataset. Therefore it enables the quick detection of features and the comparison of several such patterns belonging to the different datasets being analysed. The sunflower diagram enables a quick and comprehensive understanding of the information about diurnal cycle of the solar radiation data. It enables in a graphical form, quick screening and long-term statistics of huge data quantities when searching for their diurnal features and

  6. Characteristics of diurnal pattern of global photosynthetically-active ...

    African Journals Online (AJOL)

    A two year data (September 1992 August 1994) on photosynhetically-active radiation (PAR) measured at Ilorin (Lat.: 832´N. Long.:434´E) using LI-190SA quantum sensor are analysed both on daily and monthly mean diurnal bases. This was done with the aim of characterizing the diurnal pattern of this radiation at this ...

  7. Diurnal cycle of the dust instantaneous direct radiative forcing over the Arabian Peninsula

    KAUST Repository

    Osipov, Sergey

    2015-08-27

    In this study we attempted to better quantify radiative effects of dust over the Arabian Peninsula and their dependence on input parameters. For this purpose we have developed a stand-alone column radiation transport model coupled with the Mie, T-matrix and geometric optics calculations and driven by reanalysis meteorological fields and atmospheric composition. Numerical experiments were carried out for a wide range of aerosol optical depths, including extreme values developed during the dust storm on 18–20 March 2012. Comprehensive ground-based observations and satellite retrievals were used to estimate aerosol optical properties, validate calculations and carry out radiation closure. The broadband surface albedo, fluxes at the bottom and top of the atmosphere as well as instantaneous dust radiative forcing were estimated both from the model and observations. Diurnal cycle of the shortwave instantaneous dust direct radiative forcing was studied for a range of aerosol and surface characteristics representative of the Arabian Peninsula. Mechanisms and parameters responsible for diurnal variability of the radiative forcing were evaluated. We found that intrinsic variability of the surface albedo and its dependence on atmospheric conditions, along with anisotropic aerosol scattering, are mostly responsible for diurnal effects.

  8. Quantifying Diurnal Cloud Radiative Effects by Cloud Type in the Tropical Western Pacific

    Energy Technology Data Exchange (ETDEWEB)

    Burleyson, Casey D.; Long, Charles N.; Comstock, Jennifer M.

    2015-06-01

    Cloud radiative effects are examined using long-term datasets collected at the three Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facilities in the tropical western Pacific. We quantify the surface radiation budget, cloud populations, and cloud radiative effects by partitioning the data by cloud type, time of day, and as a function of large scale modes of variability such as El Niño Southern Oscillation (ENSO) phase and wet/dry seasons at Darwin. The novel facet of our analysis is that we break aggregate cloud radiative effects down by cloud type across the diurnal cycle. The Nauru cloud populations and subsequently the surface radiation budget are strongly impacted by ENSO variability whereas the cloud populations over Manus only shift slightly in response to changes in ENSO phase. The Darwin site exhibits large seasonal monsoon related variations. We show that while deeper convective clouds have a strong conditional influence on the radiation reaching the surface, their limited frequency reduces their aggregate radiative impact. The largest source of shortwave cloud radiative effects at all three sites comes from low clouds. We use the observations to demonstrate that potential model biases in the amplitude of the diurnal cycle and mean cloud frequency would lead to larger errors in the surface energy budget compared to biases in the timing of the diurnal cycle of cloud frequency. Our results provide solid benchmarks to evaluate model simulations of cloud radiative effects in the tropics.

  9. Pulse pressure and diurnal blood pressure variation

    DEFF Research Database (Denmark)

    Knudsen, Søren Tang; Poulsen, Per Løgstrup; Hansen, Klavs Würgler

    2002-01-01

    retinopathy, nephropathy, macrovascular disease, PP, and diurnal BP variation in a group of type 2 diabetic patients. METHODS: In 80 type 2 diabetic patients we performed 24-h ambulatory BP (AMBP) and fundus photographs. Urinary albumin excretion was evaluated by urinary albumin/creatinine ratio. Presence...... or absence of macrovascular disease was assessed by an independent physician. RESULTS: Forty-nine patients had no detectable retinal changes (grade 1), 13 had grade 2 retinopathy, and 18 had more advanced retinopathy (grades 3-6). Compared to patients without retinopathy (grade 1), patients with grades 2......BACKGROUND: In nondiabetic subjects pulse pressure (PP) is an independent predictor of cardiovascular disease and microalbuminuria. Reduced circadian blood pressure (BP) variation is a potential risk factor for the development of diabetic complications. We investigated the association between...

  10. Diurnal and semi-diurnal tidal structures due to O2, O3 and H2O ...

    Indian Academy of Sciences (India)

    from World Meteorological Organization (WMO. 1986), while the Rayleigh scattering cross section was calculated using the formula of Nicolet (1984). ..... Figure 5(a) exhibits the exponential growth of diurnal amplitude with altitude, at low to mid lat- itudes. At high latitudes, the diurnal amplitude decreases with altitude due to ...

  11. Photometric Modeling of Simulated Surace-Resolved Bennu Images

    Science.gov (United States)

    Golish, D.; DellaGiustina, D. N.; Clark, B.; Li, J. Y.; Zou, X. D.; Bennett, C. A.; Lauretta, D. S.

    2017-12-01

    The Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) is a NASA mission to study and return a sample of asteroid (101955) Bennu. Imaging data from the mission will be used to develop empirical surface-resolved photometric models of Bennu at a series of wavelengths. These models will be used to photometrically correct panchromatic and color base maps of Bennu, compensating for variations due to shadows and photometric angle differences, thereby minimizing seams in mosaicked images. Well-corrected mosaics are critical to the generation of a global hazard map and a global 1064-nm reflectance map which predicts LIDAR response. These data products directly feed into the selection of a site from which to safely acquire a sample. We also require photometric correction for the creation of color ratio maps of Bennu. Color ratios maps provide insight into the composition and geological history of the surface and allow for comparison to other Solar System small bodies. In advance of OSIRIS-REx's arrival at Bennu, we use simulated images to judge the efficacy of both the photometric modeling software and the mission observation plan. Our simulation software is based on USGS's Integrated Software for Imagers and Spectrometers (ISIS) and uses a synthetic shape model, a camera model, and an empirical photometric model to generate simulated images. This approach gives us the flexibility to create simulated images of Bennu based on analog surfaces from other small Solar System bodies and to test our modeling software under those conditions. Our photometric modeling software fits image data to several conventional empirical photometric models and produces the best fit model parameters. The process is largely automated, which is crucial to the efficient production of data products during proximity operations. The software also produces several metrics on the quality of the observations themselves, such as surface coverage and the

  12. Diurnal modulation and sources of variation affecting ventricular repolarization in Warmblood horses

    DEFF Research Database (Denmark)

    Pedersen, Philip Juul; Moeller, Sine B.; Madsen, Mette Flethøj

    2014-01-01

    Te) are used as repolarization markers. To support the use of these markers in horses, we sought to describe the possible influence of the environment, time of day, day-to-day effects, T wave conformation, age, body weight (BW), and horse-to-horse variation on repolarization measurements. ANIMALS: 12 Warmblood...... affecting these intervals. RESULTS: Differences between individual horses were the largest source of repolarization variability although the environment had a significant effect on repolarization as well. Diurnal variation affected both the RR interval and the repolarization markers. The QT, QTc and Tp......, diurnal variation, the environment, and T wave conformation. These factors must be considered if markers of equine repolarization are used diagnostically....

  13. Optical Photometric Observations of GEO Debris

    Science.gov (United States)

    Seitzer, Patrick; Rodriquez-Cowardin, Heather M.; Barker, Edwin S.; Abercromby, Kira J.; Kelecy, Thomas M.; Horstman, Matt

    2010-01-01

    We report on a continuing program of optical photometric measurements of faint orbital debris at geosynchronous Earth orbit (GEO). These observations can be compared with laboratory studies of actual spacecraft materials in an effort to determine what the faint debris at GEO may be. We have optical observations from Cerro Tololo Inter-American Observatory (CTIO) in Chile of two samples of debris: 1. GEO objects discovered in a survey with the University of Michigan's 0.6-m aperture Curtis-Schmidt telescope MODEST (for Michigan Orbital DEbris Survey Telescope), and then followed up in real-time with the CTIO/SMARTS 0.9-m for orbits and photometry. Our goal is to determine 6 parameter orbits and measure colors for all objects fainter than R = 15 t11 magnitude that are discovered in the MODEST survey. 2. A smaller sample of high area to mass ratio (AMR) objects discovered independently, and acquired using predictions from orbits derived from independent tracking data collected days prior to the observations. Our optical observations in standard astronomical BVRI filters are done with either telescope, and with the telescope tracking the debris object at the object's angular rate. Observations in different filters are obtained sequentially. We have obtained 71 calibrated sequences of R-B-V-I-R magnitudes. A total of 66 of these sequences have 3 or more good measurements in all filters (not contaminated by star streaks or in Earth's shadow). Most of these sequences show brightness variations, but a small subset has observed brightness variations consistent with that expected from observational errors alone. The majority of these stable objects are redder than a solar color in both B-R and R-I. There is no dependence on color with brightness. For a smaller sample of objects we have observed with synchronized CCD cameras on the two telescopes. The CTIO 0.9-m observes in B, and MODEST in R. The CCD cameras are electronically linked together so that the start time and

  14. Photometric Studies of Orbital Debris at GEO

    Science.gov (United States)

    Seitzer, Patrick; Cowardin, Heather M.; Barker, Ed; Abercromby, Kira J.; Foreman, Gary; Hortsman, Matt

    2009-01-01

    Orbital debris represents a significant and increasing risk to operational spacecraft. Here we report on photometric observations made in standard BVRI filters at the Cerro Tololo Inter-American Observatory (CTIO) in an effort to determine the physical characteristics of optically faint debris at geosynchronous Earth orbit (GEO). Our sample is taken from GEO objects discovered in a survey with the University of Michigan s 0.6-m Curtis-Schmidt telescope (known as MODEST, for Michigan Orbital DEbris Survey Telescope), and then followed up in real-time with the CTIO/SMARTS 0.9-m for orbits and photometry. For a sample of 50 objects, calibrated sequences in RB- V-I-R filters have been obtained with the CTIO/SMARTS 0.9-m. For objects that do not show large brightness variations, the colors are largely redder than solar in both B-R and R-I. The width of the color distribution may be intrinsic to the nature of the surfaces, but also could imply that we are seeing irregularly shaped objects and measuring the colors at different times with just one telescope. For irregularly shaped objects tumbling at unknown orientations and rates, such sequential filter measurements using one telescope are subject to large errors for interpretation. If all observations in all filters in a particular sequence are of the same surface at the same solar and viewing angles, then the colors are meaningful. Where this is not the case, interpretation of the observed colors is impossible. For a smaller sample of objects we have observed with synchronized CCD cameras on the two telescopes. The CTIO/SMARTS 0.9-m observes in B, and the Schmidt in R. The CCD cameras are electronically linked together so that the start time and duration of observations are both the same to better than 50 milliseconds. Now the observed B-R color is a true measure of the scattered illuminated area of the debris piece for that observation.

  15. Photometric Studies of GEO Orbital Debris

    Science.gov (United States)

    Seitzer, Patrick; Rodriquez-Cowardin, Heather M.; Barker, Ed; Abercromby, Kira J.; Foreman, Gary; Horstman, Matt

    2009-01-01

    The photometric signature of a debris object can be useful in determining what the physical characteristics of a piece of debris are. We report on optical observations in multiple filters of debris at geosynchronous Earth orbit (GEO). Our sample is taken from GEO objects discovered in a survey with the University of Michigan's 0.6-m aperture Schmidt telescope MODEST (for Michigan Orbital DEbris Survey Telescope), and then followed up in real-time with the Cerro Tololo Inter- American Observatory (CTIO) 0.9-m for orbits and photometry. Our goal is to determine 6 parameter orbits and measure colors for all objects fainter than R=15th magnitude that are discovered in the MODEST survey. At this magnitude the distribution of observed angular rates changes significantly from that of brighter objects. There are two objectives: 1. Estimate the orbital distribution of objects selected on the basis of two observational criteria: brightness (magnitude) and angular rates. 2. Obtain magnitudes and colors in standard astronomical filters (BVRI) for comparison with reflectance spectra of likely spacecraft materials. What is the faint debris likely to be? More than 90 calibrated sequences of R-B-V-I-R magnitudes for a sample of 50 objects have been obtained with the CTIO 0.9-m. For objects that do not show large brightness variations, the colors are largely redder than solar in both B-R and R-I. The width of the color distribution may be intrinsic to the nature of the surfaces, but also could be that we are seeing irregularly shaped objects and measuring the colors at different times with just one telescope. For a smaller sample of objects we have observed with synchronized CCD cameras on the two telescopes. The CTIO 0.9-m observes in B, and MODEST in R. The CCD cameras are electronically linked together so that the start time and duration of observations are the same to better than 50 milliseconds. Thus the B-R color is a true measure of the surface of the debris piece facing the

  16. Photometric redshifts of galaxies from SDSS and 2MASS

    International Nuclear Information System (INIS)

    Wang Tao; Gu Qiusheng; Huang Jiasheng

    2009-01-01

    In order to find the physical parameters which determine the accuracy of photometric redshifts, we compare the spectroscopic and photometric redshifts (photo-z's) for a large sample of ∼ 80000 SDSS-2MASS galaxies. Photo-z's in this paper are estimated by using the artificial neural network photometric redshift method (ANNz). For a subset of ∼40000 randomly selected galaxies, we find that the photometric redshift recovers the spectroscopic redshift distribution very well with rms of 0.016. Our main results are as follows: (1) Using magnitudes directly as input parameters produces more accurate photo-z's than using colors; (2) The inclusion of 2MASS (J, H, K s ) bands does not improve photo-z's significantly, which indicates that near infrared data might not be important for the low-redshift sample; (3) Adding the concentration index (essentially the steepness of the galaxy brightness profile) as an extra input can improve the photo-z's estimation up to ∼ 10 percent; (4) Dividing the sample into early- and late-type galaxies by using the concentration index, normal and abnormal galaxies by using the emission line flux ratios, and red and blue galaxies by using color index (g - r), we can improve the accuracy of photo-z's significantly; (5) Our analysis shows that the outliers (where there is a big difference between the spectroscopic and photometric redshifts) are mainly correlated with galaxy types, e.g., most outliers are late-type (blue) galaxies.

  17. OPTICAL PHOTOMETRIC AND POLARIMETRIC INVESTIGATION OF NGC 1931

    International Nuclear Information System (INIS)

    Pandey, A. K.; Eswaraiah, C.; Sharma, Saurabh; Yadav, Ram Kesh; Samal, M. R.; Chauhan, N.; Chen, W. P.; Jose, J.; Ojha, D. K.; Chandola, H. C.

    2013-01-01

    We present optical photometric and polarimetric observations of stars toward NGC 1931 with the aim of deriving cluster parameters such as distance, reddening, age, and luminosity/mass function as well as understanding dust properties and star formation in the region. The distance to the cluster is found to be 2.3 ± 0.3 kpc and the reddening E(B – V) in the region is found to be variable. The stellar density contours reveal two clusters in the region. The observations suggest a differing reddening law within the cluster region. Polarization efficiency of the dust grains toward the direction of the cluster is found to be less than that for the general diffuse interstellar medium (ISM). The slope of the mass function (–0.98 ± 0.22) in the southern region in the mass range of 0.8 ☉ < 9.8 is found to be shallower in comparison to that in the northern region (–1.26 ± 0.23), which is comparable to the Salpeter value (–1.35). The K-band luminosity function (KLF) of the region is found to be comparable to the average value of the slope (∼0.4) for young clusters obtained by Lada and Lada; however, the slope of the KLF is steeper in the northern region as compared to the southern region. The region is probably ionized by two B2 main-sequence-type stars. The mean age of the young stellar objects (YSOs) is found to be 2 ± 1 Myr, which suggests that the identified YSOs could be younger than the ionizing sources of the region. The morphology of the region, the distribution and ages of the YSOs, and ionizing sources indicate a triggered star formation in the region.

  18. On a New Technique for Discovering Variable Stars

    Directory of Open Access Journals (Sweden)

    Mironov A. V.

    2003-12-01

    Full Text Available A technique for discovering variable stars based on the calculation of the correlation coefficients is proposed. Applications of the technique are shown on the results of numerical experiments and on the Hipparcos photometric data.

  19. Cosmological forecasts from photometric measurements of the angular correlation function

    International Nuclear Information System (INIS)

    Sobreira, F.; Rosenfeld, R.; Simoni, F. de; Costa, L. A. N. da; Maia, M. A. G.; Makler, M.

    2011-01-01

    We study forecasts for the accuracy of the determination of cosmological parameters from future large-scale photometric surveys obtained using the full shape of the 2-point galaxy angular correlation function. The effects of linear redshift-space distortion, photometric redshift Gaussian errors, galaxy bias and nonlinearities in the power spectrum are included on our analysis. The Fisher information matrix is constructed with the full covariance matrix, including the correlation between nearby redshift shells arising from the photometric redshift error. We show that under some reasonable assumptions, a survey such as the imminent Dark Energy Survey should be able to constrain the dark energy equation of state parameter w and the cold dark matter density Ω cdm with a precision of the order of 20% and 13%, respectively, from the full shape of the angular correlation function alone. When combined with priors from other observations the precision in the determination of these parameters improve to 8% and 4%, respectively.

  20. Morphological and photometric studies of galaxies by electronography

    International Nuclear Information System (INIS)

    Youll, D.P.

    1978-10-01

    Astronomical sources of low surface brightness, or sources with high luminosity gradients can be difficult to observe with photographic techniques. However, developments in electronographic techniques over recent years have made them suitable for precise observations of such objects. The use of these techniques for morphological and photometric studies of galaxies is discussed. Where appropriate, improvements in the methods for recovering information from electronographs, and analysing the data with computers are suggested. These techniques were used to study eight galaxy systems which have compact parts where the luminosity gradients are relatively high. Morphological studies of these systems are presented, together with measurements of some of their photometric parameters. The galaxy NGC 4881 was also studied so that the photometric calibration could be checked against previous studies, and so that the parameters of compact galaxies could be compared against this elliptical galaxy. (author)

  1. Photometric Analysis in the Kepler Science Operations Center Pipeline

    Science.gov (United States)

    Twicken, Joseph D.; Clarke, Bruce D.; Bryson, Stephen T.; Tenenbaum, Peter; Wu, Hayley; Jenkins, Jon M.; Girouard, Forrest; Klaus, Todd C.

    2010-01-01

    We describe the Photometric Analysis (PA) software component and its context in the Kepler Science Operations Center (SOC) pipeline. The primary tasks of this module are to compute the photometric flux and photocenters (centroids) for over 160,000 long cadence (thirty minute) and 512 short cadence (one minute) stellar targets from the calibrated pixels in their respective apertures. We discuss the science algorithms for long and short cadence PA: cosmic ray cleaning; background estimation and removal; aperture photometry; and flux-weighted centroiding. We discuss the end-to-end propagation of uncertainties for the science algorithms. Finally, we present examples of photometric apertures, raw flux light curves, and centroid time series from Kepler flight data. PA light curves, centroid time series, and barycentric timestamp corrections are exported to the Multi-mission Archive at Space Telescope [Science Institute] (MAST) and are made available to the general public in accordance with the NASA/Kepler data release policy.

  2. Photometric behavior of SS 433 in 1979 and 1980

    International Nuclear Information System (INIS)

    Mazeh, T.; Tel Aviv University; Wise Observatory, Tel Aviv, Israel); Leibowitz, E.M.; Wise Observatory, Tel Aviv, Israel)

    1981-01-01

    Results and analysis of photometric measurements performed in the last two observing seasons of SS 433 are presented. The light of the star in the V and the B photometric bands varies with a period of either 6.55 or 6.43 days. The periodicity of approximately 164 days is also apparent in the photometric data, with its first and third harmonics. Fluctuations of the order of a half a magnitude within a few hours have also been recorded. The B-V color shows no dependence on the phase of the periodic variations, while it does change by up to 0.25 mag, in an apparent association with the short time scale fluctuations

  3. CHARACTERIZING AND PROPAGATING MODELING UNCERTAINTIES IN PHOTOMETRICALLY DERIVED REDSHIFT DISTRIBUTIONS

    International Nuclear Information System (INIS)

    Abrahamse, Augusta; Knox, Lloyd; Schmidt, Samuel; Thorman, Paul; Anthony Tyson, J.; Zhan Hu

    2011-01-01

    The uncertainty in the redshift distributions of galaxies has a significant potential impact on the cosmological parameter values inferred from multi-band imaging surveys. The accuracy of the photometric redshifts measured in these surveys depends not only on the quality of the flux data, but also on a number of modeling assumptions that enter into both the training set and spectral energy distribution (SED) fitting methods of photometric redshift estimation. In this work we focus on the latter, considering two types of modeling uncertainties: uncertainties in the SED template set and uncertainties in the magnitude and type priors used in a Bayesian photometric redshift estimation method. We find that SED template selection effects dominate over magnitude prior errors. We introduce a method for parameterizing the resulting ignorance of the redshift distributions, and for propagating these uncertainties to uncertainties in cosmological parameters.

  4. Photometric imaging in particle size measurement and surface visualization.

    Science.gov (United States)

    Sandler, Niklas

    2011-09-30

    The aim of this paper is to give an insight into photometric particle sizing approaches, which differ from the typical particle size measurement of dispersed particles. These approaches can often be advantageous especially for samples that are moist or cohesive, when dispersion of particles is difficult or sometimes impossible. The main focus of this paper is in the use of photometric stereo imaging. The technique allows the reconstruction of three-dimensional images of objects using multiple light sources in illumination. The use of photometric techniques is demonstrated in at-line measurement of granules and on-line measurement during granulation and dry milling. Also, surface visualization and roughness measurements are briefly discussed. Copyright © 2010 Elsevier B.V. All rights reserved.

  5. METAPHOR: Probability density estimation for machine learning based photometric redshifts

    Science.gov (United States)

    Amaro, V.; Cavuoti, S.; Brescia, M.; Vellucci, C.; Tortora, C.; Longo, G.

    2017-06-01

    We present METAPHOR (Machine-learning Estimation Tool for Accurate PHOtometric Redshifts), a method able to provide a reliable PDF for photometric galaxy redshifts estimated through empirical techniques. METAPHOR is a modular workflow, mainly based on the MLPQNA neural network as internal engine to derive photometric galaxy redshifts, but giving the possibility to easily replace MLPQNA with any other method to predict photo-z's and their PDF. We present here the results about a validation test of the workflow on the galaxies from SDSS-DR9, showing also the universality of the method by replacing MLPQNA with KNN and Random Forest models. The validation test include also a comparison with the PDF's derived from a traditional SED template fitting method (Le Phare).

  6. CALIBRATING PHOTOMETRIC REDSHIFT DISTRIBUTIONS WITH CROSS-CORRELATIONS

    International Nuclear Information System (INIS)

    Schulz, A. E.

    2010-01-01

    The next generation of proposed galaxy surveys will increase the number of galaxies with photometric redshift identifications by two orders of magnitude, drastically expanding both the redshift range and detection threshold from the current state of the art. Obtaining spectra for a fair subsample of these new data could be cumbersome and expensive. However, adequate calibration of the true redshift distribution of galaxies is vital to tapping the potential of these surveys to illuminate the processes of galaxy evolution and to constrain the underlying cosmology and growth of structure. We examine here an alternative to direct spectroscopic follow-up: calibration of the redshift distribution of photometric galaxies via cross-correlation with an overlapping spectroscopic survey whose members trace the same density field. We review the theory, develop a pipeline to implement the method, apply it to mock data from N-body simulations, and examine the properties of this redshift distribution estimator. We demonstrate that the method is generally effective, but the estimator is weakened by two main factors. One is that the correlation function of the spectroscopic sample must be measured in many bins along the line of sight, which renders the measurement noisy and interferes with high-quality reconstruction of the photometric redshift distribution. Also, the method is not able to disentangle the photometric redshift distribution from redshift dependence in the bias of the photometric sample. We establish the impact of these factors using our mock catalogs. We conclude that it may still be necessary to spectroscopically follow up a fair subsample of the photometric survey data. Nonetheless, it is significant that the method has been successfully implemented on mock data, and with further refinement it may appreciably decrease the number of spectra that will be needed to calibrate future surveys.

  7. Photometric Redshifts with the LSST: Evaluating Survey Observing Strategies

    Science.gov (United States)

    Graham, Melissa L.; Connolly, Andrew J.; Ivezić, Željko; Schmidt, Samuel J.; Jones, R. Lynne; Jurić, Mario; Daniel, Scott F.; Yoachim, Peter

    2018-01-01

    In this paper we present and characterize a nearest-neighbors color-matching photometric redshift estimator that features a direct relationship between the precision and accuracy of the input magnitudes and the output photometric redshifts. This aspect makes our estimator an ideal tool for evaluating the impact of changes to LSST survey parameters that affect the measurement errors of the photometry, which is the main motivation of our work (i.e., it is not intended to provide the “best” photometric redshifts for LSST data). We show how the photometric redshifts will improve with time over the 10 year LSST survey and confirm that the nominal distribution of visits per filter provides the most accurate photo-z results. The LSST survey strategy naturally produces observations over a range of airmass, which offers the opportunity of using an SED- and z-dependent atmospheric affect on the observed photometry as a color-independent redshift indicator. We show that measuring this airmass effect and including it as a prior has the potential to improve the photometric redshifts and can ameliorate extreme outliers, but that it will only be adequately measured for the brightest galaxies, which limits its overall impact on LSST photometric redshifts. We furthermore demonstrate how this airmass effect can induce a bias in the photo-z results, and caution against survey strategies that prioritize high-airmass observations for the purpose of improving this prior. Ultimately, we intend for this work to serve as a guide for the expectations and preparations of the LSST science community with regard to the minimum quality of photo-z as the survey progresses.

  8. Photometric measurements of solar irradiance variations due to sunspots

    International Nuclear Information System (INIS)

    Chapman, G.A.; Herzog, A.D.; Laico, D.E.; Lawrence, J.K.; Templer, M.S.

    1989-01-01

    A photometric telescope constructed to obtain photometric sunspot areas and deficits on a daily basis is described. Data from this Cartesian full disk telescope (CFDT) are analyzed with attention given to the period between June 4 and June 17, 1985 because of the availability of overlapping sunspot area and irradiance deficit data from high-resolution digital spectroheliograms made with the San Fernando Observatory 28 cm vacuum solar telescope and spectroheliograph. The CFDT sunspot deficits suggest a substantial irradiance contribution from faculae and active region plage. 23 refs

  9. Galaxy Tagging: photometric redshift refinement and group richness enhancement

    Science.gov (United States)

    Kafle, P. R.; Robotham, A. S. G.; Driver, S. P.; Deeley, S.; Norberg, P.; Drinkwater, M. J.; Davies, L. J.

    2018-06-01

    We present a new scheme, galtag, for refining the photometric redshift measurements of faint galaxies by probabilistically tagging them to observed galaxy groups constructed from a brighter, magnitude-limited spectroscopy survey. First, this method is tested on the DESI light-cone data constructed on the GALFORM galaxy formation model to tests its validity. We then apply it to the photometric observations of galaxies in the Kilo-Degree Imaging Survey (KiDS) over a 1 deg2 region centred at 15h. This region contains Galaxy and Mass Assembly (GAMA) deep spectroscopic observations (i-bandhttps://github.com/pkaf/galtag.git.

  10. Photometric investigation of the magnetic star 53 Camelopardalis

    International Nuclear Information System (INIS)

    Muciek, M.; Gertner, J.; North, P.; Rufener, F.

    1985-01-01

    New photometric results obtained in the Geneva system are presented for the star 53 Cam. Earlier photometric results obtained in another system are used as well to show the existence of about four ''null-wavelength regions'' between 3400 and 7700 A and to draw the pseudocontinuum of this star. Assuming axisymmetry about the magnetic axis, a simple model of brightness and equivalent width distribution on the surface of the star are proposed. The distribution of the intensity of the γ 5200 depression is given and a slight inhomogeneity of the distribution of effective temperature is suggested. 28 refs., 7 figs., 4 tabs. (author)

  11. [Determination of aluminium in flour foods with photometric method].

    Science.gov (United States)

    Ma, Lan; Zhao, Xin; Zhou, Shuang; Yang, Dajin

    2012-05-01

    To establish a determination method for aluminium in flour foods with photometric method. After samples being treated with microwave digestion and wet digestion, aluminium in staple flour foods was determined by photometric method. There was a good linearity of the result in the range of 0.25 - 5.0 microg/ml aluminium, r = 0.9998; limit of detection (LOD) : 2.3 ng/ml; limit of quantitation (LOQ) : 7 ng/ml. This method of determining aluminium in flour foods is simple, rapid and reliable.

  12. Kinematics and age of 15 stars-photometric solar analogs

    Science.gov (United States)

    Galeev, A. I.; Shimansky, V. V.

    2008-03-01

    The radial and space velocities are inferred for 15 stars that are photometric analogs of the Sun. The space velocity components (U, V, W) of most of these stars lie within the 10-60 km/s interval. The star HD 225239, which in our previous papers we classified as a subgiant, has a space velocity exceeding 100 km/s, and belongs to the thick disk. The inferred fundamental parameters of the atmospheres of solar analogs are combined with published evolutionary tracks to estimate the masses and ages of the stars studied. The kinematics of photometric analogs is compared to the data for a large group of solar-type stars.

  13. INFLUENCE OF REAGENT PURITY ON THE ION CHROMATOGRAPHIC DETERMINATION OF BROMATE IN WATER USING 3,3'-DIMETHOXYBENZIDINE AS A PROCHROMOPHORE FOR PHOTOMETRIC DETECTION

    Science.gov (United States)

    Variable availability of the purified dihydrochloride salt of 3,3'-dimethoxybenzidine (DMB, ortho-dianisidine) led us to investigate the effects of reagent purity on the analytical results obtinaed when this reagent is used in the photometric determination of the disinfection byp...

  14. Characterisation and quantification of regional diurnal SST cycles from SEVIRI

    DEFF Research Database (Denmark)

    Karagali, Ioanna; Høyer, J.L.

    2014-01-01

    seas. Six years of SST fields from SEVIRI are validated against the Advanced Along-Track Scanning Radiometer (AATSR) Reprocessed for Climate (ARC) data set. The overall SEVIRI–AATSR bias is −0.07 K, and the standard deviation is 0.51 K, based on more than 53×106 matchups. Identification of the diurnal...... in the tropics. Longer diurnal warming duration is identified in the high latitudes compared to the tropics. The maximum monthly mean diurnal signal can be up to 0.5K in specific regions....

  15. Influence of entrainment and countergradient on the ABL diurnal development

    Science.gov (United States)

    Hernández-Ceballos, M. A.

    2009-09-01

    The representation of the diurnal evolution of the boundary layer (ABL) by NCAR-Penn State Mesoscale Model (MM5) and by the mesoscale model Weather Research Forecast (WRF) is compared. Special attention is paid to determine the role of processes that occur near and below the inversion zone: the positive correlation between the heat flux and the gradient (countergradient) and the role of entrainment of heat originating from the free troposphere. Both processes play a key role in the modelling of the diurnal variability of temperature, moisture and atmospheric compounds. A number of 13 simulations are carried out to determine the sensitivity of the model results to the formulation of the ABL height and countergradient heat flux in the Medium Range Forecast (MRF) ABL scheme. Model results are compared with experimental data obtained from the DOMINO (Diel Oxidant Mechanisms in relation to Nitrogen oxides) campaign. It was organized by Max Planck Institute for Atmospheric Chemistry (Germany) in collaboration with the National Institute for Aerospace Technology (Spain). The DOMINO campaign took place at the "Atmospheric Sounding Station - El Arenosillo", a platform dedicated to atmospheric measurements in the Southwest of Spain. All numerical experiments are grouped in four clusters, each focussing on the sensitivity of different relevant aspects. The following aspects of the formulation are analyzed: surface moisture availability (M), the countergradient term (γc) and the ABL height (h). This is done by modifying both the bulk critical Richardson number (Ric) at the inversion zone, and a coefficient of proportionality (b) that determines the excess temperature and countergradient. The importance of b is due to its direct relation in the definition of both, γc and h. The results got with MM5 model show that temperature and specific moisture temporal evolution is not very sensitive to changes in the soil moisture availability (M value from 0.6 to 0.1). Using the MRF

  16. Range of monthly mean hourly land surface air temperature diurnal cycle over high northern latitudes

    Science.gov (United States)

    Wang, Aihui; Zeng, Xubin

    2014-05-01

    Daily maximum and minimum temperatures over global land are fundamental climate variables, and their difference represents the diurnal temperature range (DTR). While the differences between the monthly averaged DTR (MDTR) and the range of monthly averaged hourly temperature diurnal cycle (RMDT) are easy to understand qualitatively, their differences have not been quantified over global land areas. Based on our newly developed in situ data (Climatic Research Unit) reanalysis (Modern-Era Retrospective analysis for Research and Applications) merged hourly temperature data from 1979 to 2009, RMDT in January is found to be much smaller than that in July over high northern latitudes, as it is much more affected by the diurnal radiative forcing than by the horizontal advection of temperature. In contrast, MDTR in January is comparable to that in July over high northern latitudes, but it is much larger than January RMDT, as it primarily reflects the movement of lower frequency synoptic weather systems. The area-averaged RMDT trends north of 40°N are near zero in November, December, and January, while the trends of MDTR are negative. These results suggest the need to use both the traditional MDTR and RMDT suggested here in future observational and modeling studies. Furthermore, MDTR and its trend are more sensitive to the starting hour of a 24 h day used in the calculations than those for RMDT, and this factor also needs to be considered in model evaluations using observational data.

  17. Mean diurnal variations of noctilucent clouds during 7 years of lidar observations at ALOMAR

    Directory of Open Access Journals (Sweden)

    J. Fiedler

    2005-06-01

    Full Text Available From 1997 to 2003, noctilucent clouds (NLC were observed by lidar above the ALOMAR observatory in Northern Norway (69° N during a total of 1880 measurement hours. This data set contains NLC signatures for 640h, covering all local times, even during the highest solar background conditions. After data limitation imposing a threshold value of 4x10-10m-1sr-1 for the volume backscatter coefficient of the NLC particles, a measure for the cloud brightness, local time dependencies of the NLC occurrence frequency, altitude, and brightness were determined. On average, over the 7 years NLC occurred during the whole day and preferably in the early morning hours, with a maximum occurrence frequency of ~40% between 4 and 7 LT. Splitting the data into weak and strong clouds yields almost identical amplitudes of diurnal and semidiurnal variations for the occurrence of weak clouds, whereas the strong clouds are dominated by the diurnal variation. NLC occurrence, altitude, as well as brightness, show a remarkable persistence concerning diurnal and semidiurnal variations from 1997 to 2003, suggesting that NLC above ALOMAR are significantly controlled by atmospheric tides. The observed mean anti-phase behavior between cloud altitude and brightness is attributed to a phase shift between the semidiurnal components by ~6h. Investigation of data for each individual year regarding the prevailing oscillation periods of the NLC parameters showed different phase relationships, leading to a complex variability in the cloud parameters.

  18. Observed diurnal variations in Mars Science Laboratory Dynamic Albedo of Neutrons passive mode data

    Science.gov (United States)

    Tate, C. G.; Moersch, J.; Jun, I.; Mitrofanov, I.; Litvak, M.; Boynton, W. V.; Drake, D.; Fedosov, F.; Golovin, D.; Hardgrove, C.; Harshman, K.; Kozyrev, A. S.; Kuzmin, R.; Lisov, D.; Maclennan, E.; Malakhov, A.; Mischna, M.; Mokrousov, M.; Nikiforov, S.; Sanin, A. B.; Starr, R.; Vostrukhin, A.

    2018-06-01

    The Mars Science Laboratory Dynamic Albedo of Neutrons (DAN) experiment measures the martian neutron leakage flux in order to estimate the amount of water equivalent hydrogen present in the shallow regolith. When DAN is operating in passive mode, it is sensitive to neutrons produced through the interactions of galactic cosmic rays (GCR) with the regolith and atmosphere and neutrons produced by the rover's Multi-Mission Radioisotope Thermoelectric Generator (MMRTG). During the mission, DAN passive mode data were collected over the full diurnal cycle at the locations known as Rocknest (sols 60-100) and John Klein (sols 166-272). A weak, but unexpected, diurnal variation was observed in the neutron count rates reported at these locations. We investigate different hypotheses that could be causing these observed variations. These hypotheses are variations in subsurface temperature, atmospheric pressure, the exchange of water vapor between the atmosphere and regolith, and instrumental effects on the neutron count rates. Our investigation suggests the most likely factors contributing to the observed diurnal variations in DAN passive data are instrumental effects and time-variable preferential shielding of alpha particles, with other environmental effects only having small contributions.

  19. Diurnal Cycle of Clouds and Precipitation at the ARM SGP Site

    Science.gov (United States)

    Zhao, W.; Marchand, R.; Fu, Q.

    2016-12-01

    Millimeter Wavelength Cloud Radar (MMCR) data from Dec. 1996 to Dec. 2010, collected at the U. S. Department of Energy Atmospheric Radiation Measurement (ARM) program site in the U.S. Southern Great Plains (SGP), are categorized into clouds (-40dBZe≤reflectivityCRM). Observational and simulated radar reflectivity are compared and further sorted into different atmospheric states identified by Evans (2014). Evans used a neutral network to take ERA-Interim state variables (i.e. horizontal winds, relative humidity, temperature at seven predetermined pressure level and surface pressure) on an 8×8 grid with 1.5º×1.5º spatial resolution centered on the SGP site and found twenty-one atmospheric states which represent specific synoptic conditions. We use these states to study the differences in the diurnal cycle between observations and simulations. Differences in the (mean) annual diurnal cycle between the observations and model are decomposed into errors in the daily mean, errors in the diurnal variation in each state, and errors due to difference in the frequency of occurrence of atmospheric states between ERA and the MMF. The magnitude of various error sources is assessed.

  20. Photometric Modeling and VIS-IR Albedo Maps of Dione From Cassini-VIMS

    Science.gov (United States)

    Filacchione, G.; Ciarniello, M.; D'Aversa, E.; Capaccioni, F.; Cerroni, P.; Buratti, B. J.; Clark, R. N.; Stephan, K.; Plainaki, C.

    2018-03-01

    We report about visible and infrared albedo maps and spectral indicators of Dione's surface derived from the complete Visual and Infrared Mapping Spectrometer (VIMS) data set acquired between 2004 and 2017 during the Cassini tour in Saturn's system. Maps are derived by applying a photometric correction necessary to disentangle the intrinsic albedo of the surface from illumination and viewing geometry occurring at the time of the observation. The photometric correction is based on the Shkuratov et al. (2011, https://doi.org/10.1016/j.pss.2011.06.011) method which yields values of the surface equigonal albedo. Dione's surface albedo maps are rendered at five visible (VIS: 0.35, 0.44, 0.55, 0.7, and 0.95 μm) and five infrared (IR: 1.046, 1.540, 1.822, 2.050, and 2.200 μm) wavelengths in cylindrical projection with a 0.5° × 0.5° angular resolution in latitude and longitude, corresponding to a spatial resolution of 4.5 km/bin. Apart from visible and infrared albedo maps, we report about the distribution of the two visible spectral slopes (0.35-0.55 and 0.55-0.95 μm) and water ice 2.050 μm band depth computed after having applied the photometric correction. The derived spectral indicators are employed to trace Dione's composition variability on both global and local scales allowing to study the dichotomy between the bright‐leading and dark‐trailing hemispheres, the distribution of fresh material on the impact craters and surrounding ejecta, and the resurfacing of the bright material within the chasmata caused by tectonism.

  1. Mars Exploration Rover Pancam Photometric Data QUBs: Definition and Example Uses.

    Science.gov (United States)

    Soderblom, J. M.; Bell, J. F.; Arvidson, R. E.; Johnson, J. R.; Johnson, M. J.; Seelos, F. P.

    2004-12-01

    Pancam multi-spectral observations acquired at the Mars Exploration Rover Spirit and Opportunity landing sites are being assembled into a multi-layer format know as a QUB. For any given pixel in a Pancam image the QUB will contain values for the radiance factor, incidence (i), emission (e), and phase (g) angles, X, Y, and Z distance in a rover-based coordinate system, disparity in number of pixels between the left and right eye images and range data. Good range data is required for the generation of a Pancam QUB. The radiance factor (I/F, where I is the measured scene radiance on sensor and π F is the incident solar irradiance) is calculated using a combination of preflight calibration data and information obtained from near-simultaneous observations of an onboard reflectance calibration target. The range, X, Y, Z and disparity data, and i, e, and g are calculated using routines developed by JPL's MIPL and Cornell. When possible, these data have been interpolated to maximize parameter coverage; a map of non-interpolated data is also included in each QUB. QUBs should prove very useful in photometric studies (e.g., Johnson et al.; Seelos, et al., this conference), detailed spectral analyses (e.g., Bell et al., this conference), and detailed topographic/DTM studies. Here we present two examples of the utilization of the information contained in Pancam QUBs. In one example we remove the photometric variability from spectra collected from multiple facets of a rock using knowledge of i, e, g and derived photometric functions. This is necessary if one wishes to conduct comparative studies of observations acquired under varying geometries and lighting conditions. In another example we present an analysis using the discrete ordinate multiple scattering radiative transfer code DISORT where we separate the atmosphere and surface contributions of the surface reflectance.

  2. Bats as prey of diurnal birds: a global perspective.

    Czech Academy of Sciences Publication Activity Database

    Mikula, P.; Morelli, Federico; Lučan, R. K.; Jones, D. N.; Tryjanowski, P.

    2016-01-01

    Roč. 46, č. 3 (2016), s. 160-174 ISSN 0305-1838 Institutional support: RVO:60077344 Keywords : avian predation hypothesis * bats * diurnal birds * nocturnality * predation Subject RIV: EG - Zoology Impact factor: 3.286, year: 2016

  3. Diurnal Change of Soil Carbon Flux of Binhai New District

    Science.gov (United States)

    Wang, T. F.; Mao, T. Y.; Ye, W.

    2018-05-01

    In order to investigate the factors influencing diurnal change of soil carbon flux of Binhai New District. Field observation experiments were carried out by using LC pro-SD photosynthetic apparatus. The diurnal changes of soil carbon flux and its environmental factors such as atmosphere temperature and soil temperature were analysed. The results indicated that soil carbon flux appeared single diurnal pattern. The diurnal average of soil carbon flux ranked from 0.2761 to 2.3367μmo1/m2/s. Soil carbon flux varied significantly among different land use regimes(Pequations (Pquadratic correlations between soil carbon flux and soil temperature (10cm). And soil temperature could account for more than 32.27% of the soil carbon flux changes (P<0.05, R2=0.3227-0.7465).

  4. Diurnal variation of tropospheric temperature at a tropical station

    Directory of Open Access Journals (Sweden)

    K. Revathy

    2001-08-01

    Full Text Available The vertical velocity in the troposphere-lower stratosphere region measured using MST radar has been utilized to evaluate the temperature profile in the region. The diurnal variation of the tropospheric temperature on one day in August 1998 at the tropical station Gadanki (13.5° N, 79.2° E has been studied using the MST radar technique. The diurnal variation of the temperature revealed a prominent diurnal variation with the peak in the afternoon hours increasingly delayed in altitude. The tropopause temperature and altitude exhibited a clear diurnal cycle.Key words. Atmospheric composition and structure (pressure, density and temperature; troposphere - composition and chemistry; instruments and technique

  5. Understanding Brown Dwarf Variability

    Science.gov (United States)

    Marley, Mark S.

    2013-01-01

    Surveys of brown dwarf variability continue to find that roughly half of all brown dwarfs are variable. While variability is observed amongst all types of brown dwarfs, amplitudes are typically greatest for L-T transition objects. In my talk I will discuss the possible physical mechanisms that are responsible for the observed variability. I will particularly focus on comparing and contrasting the effects of changes in atmospheric thermal profile and cloud opacity. The two different mechanisms will produce different variability signatures and I will discuss the extent to which the current datasets constrain both mechanisms. By combining constraints from studies of variability with existing spectral and photometric datasets we can begin to construct and test self-consistent models of brown dwarf atmospheres. These models not only aid in the interpretation of existing objects but also inform studies of directly imaged giant planets.

  6. Sleep duration partially accounts for race differences in diurnal cortisol dynamics.

    Science.gov (United States)

    Peterson, Laurel M; Miller, Karissa G; Wong, Patricia M; Anderson, Barbara P; Kamarck, Thomas W; Matthews, Karen A; Kirschbaum, Clemens; Manuck, Stephen B

    2017-05-01

    Emerging research demonstrates race differences in diurnal cortisol slope, an indicator of hypothalamic-pituitary-adrenocortical (HPA)-axis functioning associated with morbidity and mortality, with African Americans showing flatter diurnal slopes than their White counterparts. Sleep characteristics are associated with both race and with HPA-axis functioning. The present report examines whether sleep duration may account for race differences in cortisol dynamics. Participants were 424 employed African American and White adults (mean age = 42.8 years, 84.2% White, 53.6% female) with no cardiovascular disease (Adult Health and Behavior Project-Phase 2 [AHAB-II] cohort, University of Pittsburgh). Cortisol slope was calculated using 4 salivary cortisol readings, averaged over each of 4 days. Demographic (age, sex), psychosocial (socioeconomic status [SES], affect, discrimination), and health behaviors (smoking, alcohol use, physical activity) variables were used as covariates, and sleep (self-report and accelerometry) was also assessed. African Americans had flatter slopes than Whites (F(1, 411) = 10.45, B = .02, p = .001) in models adjusting for demographic, psychosocial, and health behavior covariates. Shorter actigraphy-assessed total sleep time was a second significant predictor of flatter cortisol slopes (F(1, 411) = 25.27, B = -.0002, p race and diurnal slope [confidence interval = .05 (lower = .014, upper .04)]. African Americans have flatter diurnal cortisol slopes than their White counterparts, an effect that may be partially attributable to race differences in nightly sleep duration. Sleep parameters should be considered in further research on race and cortisol. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  7. Diurnal Transcriptome and Gene Network Represented through Sparse Modeling in Brachypodium distachyon

    Directory of Open Access Journals (Sweden)

    Satoru Koda

    2017-11-01

    Full Text Available We report the comprehensive identification of periodic genes and their network inference, based on a gene co-expression analysis and an Auto-Regressive eXogenous (ARX model with a group smoothly clipped absolute deviation (SCAD method using a time-series transcriptome dataset in a model grass, Brachypodium distachyon. To reveal the diurnal changes in the transcriptome in B. distachyon, we performed RNA-seq analysis of its leaves sampled through a diurnal cycle of over 48 h at 4 h intervals using three biological replications, and identified 3,621 periodic genes through our wavelet analysis. The expression data are feasible to infer network sparsity based on ARX models. We found that genes involved in biological processes such as transcriptional regulation, protein degradation, and post-transcriptional modification and photosynthesis are significantly enriched in the periodic genes, suggesting that these processes might be regulated by circadian rhythm in B. distachyon. On the basis of the time-series expression patterns of the periodic genes, we constructed a chronological gene co-expression network and identified putative transcription factors encoding genes that might be involved in the time-specific regulatory transcriptional network. Moreover, we inferred a transcriptional network composed of the periodic genes in B. distachyon, aiming to identify genes associated with other genes through variable selection by grouping time points for each gene. Based on the ARX model with the group SCAD regularization using our time-series expression datasets of the periodic genes, we constructed gene networks and found that the networks represent typical scale-free structure. Our findings demonstrate that the diurnal changes in the transcriptome in B. distachyon leaves have a sparse network structure, demonstrating the spatiotemporal gene regulatory network over the cyclic phase transitions in B. distachyon diurnal growth.

  8. Topography induced spatial variations in diurnal cycles of assimilation and latent heat of Mediterranean forest

    Science.gov (United States)

    van der Tol, C.; Dolman, A. J.; Waterloo, M. J.; Raspor, K.

    2007-02-01

    The aim of this study is to explain topography induced spatial variations in the diurnal cycles of assimilation and latent heat of Mediterranean forest. Spatial variations of the fluxes are caused by variations in weather conditions and in vegetation characteristics. Weather conditions reflect short-term effects of climate, whereas vegetation characteristics, through adaptation and acclimation, long-term effects of climate. In this study measurements of plant physiology and weather conditions are used to explain observed differences in the fluxes. A model is used to study which part of the differences in the fluxes is caused by weather conditions and which part by vegetation characteristics. Data were collected at four experimental sub-Mediterranean deciduous forest plots in a heterogeneous terrain with contrasting aspect, soil water availability, humidity and temperature. We used a sun-shade model to scale fluxes from leaf to canopy, and calculated the canopy energy balance. Parameter values were derived from measurements of light interception, leaf chamber photosynthesis, leaf nitrogen content and 13C isotope discrimination in leaf material. Leaf nitrogen content is a measure of photosynthetic capacity, and 13C isotope discrimination of water use efficiency. For validation, sap-flux based measurements of transpiration were used. The model predicted diurnal cycles of transpiration and stomatal conductance, both their magnitudes and differences in afternoon stomatal closure between slopes of different aspect within the confidence interval of the validation data. Weather conditions mainly responsible for the shape of the diurnal cycles, and vegetation parameters for the magnitude of the fluxes. Although the data do not allow for a quantification of the two effects, the differences in vegetation parameters and weather among the plots and the sensitivity of the fluxes to them suggest that the diurnal cycles were more strongly affected by spatial variations in

  9. Topography induced spatial variations in diurnal cycles of assimilation and latent heat of Mediterranean forest

    Directory of Open Access Journals (Sweden)

    C. van der Tol

    2007-01-01

    Full Text Available The aim of this study is to explain topography induced spatial variations in the diurnal cycles of assimilation and latent heat of Mediterranean forest. Spatial variations of the fluxes are caused by variations in weather conditions and in vegetation characteristics. Weather conditions reflect short-term effects of climate, whereas vegetation characteristics, through adaptation and acclimation, long-term effects of climate. In this study measurements of plant physiology and weather conditions are used to explain observed differences in the fluxes. A model is used to study which part of the differences in the fluxes is caused by weather conditions and which part by vegetation characteristics. Data were collected at four experimental sub-Mediterranean deciduous forest plots in a heterogeneous terrain with contrasting aspect, soil water availability, humidity and temperature. We used a sun-shade model to scale fluxes from leaf to canopy, and calculated the canopy energy balance. Parameter values were derived from measurements of light interception, leaf chamber photosynthesis, leaf nitrogen content and 13C isotope discrimination in leaf material. Leaf nitrogen content is a measure of photosynthetic capacity, and 13C isotope discrimination of water use efficiency. For validation, sap-flux based measurements of transpiration were used. The model predicted diurnal cycles of transpiration and stomatal conductance, both their magnitudes and differences in afternoon stomatal closure between slopes of different aspect within the confidence interval of the validation data. Weather conditions mainly responsible for the shape of the diurnal cycles, and vegetation parameters for the magnitude of the fluxes. Although the data do not allow for a quantification of the two effects, the differences in vegetation parameters and weather among the plots and the sensitivity of the fluxes to them suggest that the diurnal cycles were more strongly affected by spatial

  10. Parents Function and Behavioral Disorders in Children with and without Diurnal Voiding Dysfunction: A Comparative Study

    Directory of Open Access Journals (Sweden)

    Parsa Yousefi

    2014-09-01

    Full Text Available Background: Diurnal voiding dysfunction is one of the most common causes of pediatric urology clinic admissions. It can cause behavioral problems for children and their parents. We lunch this study to compare the parents’ function and children’s behavior problem in pediatric patients suffering from diurnal voiding dysfunction referring Arak Amir Kabir hospital. Materials and Methods: To perform this case-control study, we recruit 116 children with diurnal voiding dysfunction and compared them with other 116 children non-affected children aged between 5 to 16 years old. The child behavior checklist (CBCL4/18 for children behavior assessment and Global Assessment of Functioning (GAF for the evaluation of their parent’s behavior was completed by the parents. Data was analyzed using ANOVA, qualitative variables and χ2 formula. Results: Among 116 patient with voiding dysfunction, 10 case (8.6% showed behavioral problem while this figure was 3 case (2.6% in the control group, denoting a significant difference (p=0.04. Moreover 20 children (17.2% in the case group and 9 children (7.8% in the control group had internalizing problem (p=0.02. Twenty two children (19% with voiding dysfunction and 8 children (6.9% in the healthy group had externalizing problem which was also a significant difference (p=0.01. As a significant difference (0.01, the parent’s average stress and behavior scores in case and control group were 3.65 and 3.76, respectively. Conclusion: The higher prevalence of behavioral problem in the children suffering from diurnal voiding dysfunction and their parent’s functional impairment highlights the importance of early parent’s intervention for early treatment and subsequently prevention of future behavioral problem in their sibling.

  11. 40 CFR 1060.105 - What diurnal requirements apply for equipment?

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 32 2010-07-01 2010-07-01 false What diurnal requirements apply for... EQUIPMENT Emission Standards and Related Requirements § 1060.105 What diurnal requirements apply for... for controlling diurnal emissions: (1) If you are subject to both running loss and diurnal emission...

  12. Morpho-z: improving photometric redshifts with galaxy morphology

    Science.gov (United States)

    Soo, John Y. H.; Moraes, Bruno; Joachimi, Benjamin; Hartley, William; Lahav, Ofer; Charbonnier, Aldée; Makler, Martín; Pereira, Maria E. S.; Comparat, Johan; Erben, Thomas; Leauthaud, Alexie; Shan, Huanyuan; Van Waerbeke, Ludovic

    2018-04-01

    We conduct a comprehensive study of the effects of incorporating galaxy morphology information in photometric redshift estimation. Using machine learning methods, we assess the changes in the scatter and outlier fraction of photometric redshifts when galaxy size, ellipticity, Sérsic index, and surface brightness are included in training on galaxy samples from the SDSS and the CFHT Stripe-82 Survey (CS82). We show that by adding galaxy morphological parameters to full ugriz photometry, only mild improvements are obtained, while the gains are substantial in cases where fewer passbands are available. For instance, the combination of grz photometry and morphological parameters almost fully recovers the metrics of 5-band photometric redshifts. We demonstrate that with morphology it is possible to determine useful redshift distribution N(z) of galaxy samples without any colour information. We also find that the inclusion of quasar redshifts and associated object sizes in training improves the quality of photometric redshift catalogues, compensating for the lack of a good star-galaxy separator. We further show that morphological information can mitigate biases and scatter due to bad photometry. As an application, we derive both point estimates and posterior distributions of redshifts for the official CS82 catalogue, training on morphology and SDSS Stripe-82 ugriz bands when available. Our redshifts yield a 68th percentile error of 0.058(1 + z), and a outlier fraction of 5.2 per cent. We further include a deep extension trained on morphology and single i-band CS82 photometry.

  13. Photometric Observation and Light Curve Analysis of Binary System ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Photometric Observation and Light Curve Analysis of Binary System ER-Orionis ... February to April 2008 with the 51 cm telescope of Biruni Observatory of Shiraz University in U, B and V filters (Johnson system) and an RCA 4509 photomultiplier. ... Articles are also visible in Web of Science immediately.

  14. Photometric Study of Fourteen Low-mass Binaries

    International Nuclear Information System (INIS)

    Korda, D.; Zasche, P.; Wolf, M.; Kučáková, H.; Vraštil, J.; Hoňková, K.

    2017-01-01

    New CCD photometric observations of fourteen short-period low-mass eclipsing binaries (LMBs) in the photometric filters I, R, and V were used for a light curve analysis. A discrepancy remains between observed radii and those derived from the theoretical modeling for LMBs, in general. Mass calibration of all observed LMBs was performed using only the photometric indices. The light curve modeling of these selected systems was completed, yielding the new derived masses and radii for both components. We compared these systems with the compilation of other known double-lined LMB systems with uncertainties of masses and radii less then 5%, which includes 66 components of binaries where both spectroscopy and photometry were combined together. All of our systems are circular short-period binaries, and for some of them, the photospheric spots were also used. A purely photometric study of the light curves without spectroscopy seems unable to achieve high enough precision and accuracy in the masses and radii to act as meaningful test of the M–R relation for low-mass stars.

  15. Stereoscopic and photometric surface reconstruction in scanning electron microscopy

    International Nuclear Information System (INIS)

    Scherer, S.

    2000-01-01

    The scanning electron microscope (SEM) is one of the most important devices to examine microscopic structures as it offers images of a high contrast range with a large depth of focus. Nevertheless, three-dimensional measurements, as desired in fracture mechanics, have previously not been accomplished. This work presents a system for automatic, robust and dense surface reconstruction in scanning electron microscopy combining new approaches in shape from stereo and shape from photometric stereo. The basic theoretical assumption for a known adaptive window algorithm is shown not to hold in scanning electron microscopy. A constraint derived from this observation yields a new, simplified, hence faster calculation of the adaptive window. The correlation measure itself is obtained by a new ordinal measure coefficient. Shape from photometric stereo in the SEM is formulated by relating the image formation process with conventional photography. An iterative photometric ratio reconstruction is invented based on photometric ratios of backscatter electron images. The performance of the proposed system is evaluated using ground truth data obtained by three alternative shape recovery devices. Most experiments showed relative height accuracy within the tolerances of the alternative devices. (author)

  16. Solving the uncalibrated photometric stereo problem using total variation

    DEFF Research Database (Denmark)

    Quéau, Yvain; Lauze, Francois Bernard; Durou, Jean-Denis

    2013-01-01

    In this paper we propose a new method to solve the problem of uncalibrated photometric stereo, making very weak assumptions on the properties of the scene to be reconstructed. Our goal is to solve the generalized bas-relief ambiguity (GBR) by performing a total variation regularization of both...

  17. Photometric observations of Earth-impacting asteroid 2008 TC(3)

    Czech Academy of Sciences Publication Activity Database

    Kozubal, M.; Gasdia, F.W.; Dantowitz, R.; Scheirich, Peter; Harris, A. W.

    2011-01-01

    Roč. 46, č. 4 (2011), s. 534-542 ISSN 1086-9379 Institutional research plan: CEZ:AV0Z10030501 Keywords : asteroid * photometric observations Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.719, year: 2011

  18. PHOTOMETRIC EVIDENCE FOR THE OSMOTIC BEHAVIOR OF RAT LIVER MICROSOMES

    Science.gov (United States)

    Tedeschi, Henry; James, Joseph M.; Anthony, William

    1963-01-01

    Electron microscope observations are consistent with the interpretation that the elements of the endoplasmic reticulum are osmotically active in situ as well as after isolation. More recently, it has been reported that microsomal suspensions equilibrate almost completely with added C14-sucrose and that no osmotic behavior is evident from photometric data. These findings were considered at variance with the electron microscope data. However, equilibration with added label simply attests to a relatively high permeability, and, in addition, the photometric data need not be critical. Osmotic volume changes, measured photometrically, may be masked by concomitant events (e.g., changes in the refractive index of the test solutions at varying osmotic pressures, breakdown of the particles, and agglutination). For these reasons the photometric experiments were repeated. In this work, the reciprocal of optical density of microsomal suspensions was found to vary linearly with the reciprocal of concentration of the medium at constant refractive index. These changes probably correspond to osmotic volume changes, since the effect was found to be (a) independent of substance used and (b) osmotically reversible. The transmission of the suspension was found to vary with the refractive index of the medium, the concentration of particles, and the wavelength of incident light, according to relationships that are similar to or identical with those obtained for mitochondrial suspensions. PMID:14064105

  19. Photometric Study of Fourteen Low-mass Binaries

    Energy Technology Data Exchange (ETDEWEB)

    Korda, D.; Zasche, P.; Wolf, M.; Kučáková, H.; Vraštil, J. [Astronomical Institute, Charles University, Faculty of Mathematics and Physics, CZ-180 00, Praha 8, V Holešovičkách 2 (Czech Republic); Hoňková, K., E-mail: korda@sirrah.troja.mff.cuni.cz [Variable Star and Exoplanet Section of Czech Astronomical Society, Vsetínská 941/78, CZ-757 01, Valašské Meziříčí (Czech Republic)

    2017-07-01

    New CCD photometric observations of fourteen short-period low-mass eclipsing binaries (LMBs) in the photometric filters I, R, and V were used for a light curve analysis. A discrepancy remains between observed radii and those derived from the theoretical modeling for LMBs, in general. Mass calibration of all observed LMBs was performed using only the photometric indices. The light curve modeling of these selected systems was completed, yielding the new derived masses and radii for both components. We compared these systems with the compilation of other known double-lined LMB systems with uncertainties of masses and radii less then 5%, which includes 66 components of binaries where both spectroscopy and photometry were combined together. All of our systems are circular short-period binaries, and for some of them, the photospheric spots were also used. A purely photometric study of the light curves without spectroscopy seems unable to achieve high enough precision and accuracy in the masses and radii to act as meaningful test of the M–R relation for low-mass stars.

  20. ESO & NOT photometric monitoring of the Cloverleaf quasar

    NARCIS (Netherlands)

    Ostensen, R; Remy, M; Lindblad, PO; Refsdal, S; Stabell, R; Surdej, J; Barthel, PD; Emanuelsen, PI; Festin, L; Gosset, E; Hainaut, O; Hakala, P; Hjelm, M; Hjorth, J; Hutsemekers, D; Jablonski, M; Kaas, AA; Kristen, H; Larsson, S; Magain, P; Pettersson, B; Pospieszalska-Surdej, A; Smette, A; Teuber, J; Thomsen, B; Van Drom, E

    1997-01-01

    The Cloverleaf quasar, H1413+117, has been photometrically monitored at ESO (La Silla, Chile) and with the NOT (La Palma, Spain) during the period 1987-1994. All good quality CCD frames have been successfully analysed using two independent methods (i.e. an automatic image decomposition technique and

  1. The Young Solar Analogs Project: Initial Photometric Results

    Science.gov (United States)

    Saken, Jon M.; Gray, R. O.; Corbally, C. J.

    2013-06-01

    Since 2007 we have been conducting spectroscopic monitoring of the Ca II H & K lines and G-band for a sample of 31 YSAs in order to better understand their activity cycles and variations, as well as the effects of young stars on their solar systems. The targets cover the spectral range of stars most likely to contain Earth analogs, F8-K2, and a broad enough range of ages, 0.3 Gyr - 1.5 Gyr, to investigate how activity level changes with stellar age. These studies are already showing possible evidence for activity cycles, large variations in starspot activity, and flaring events. In order to obtain a more complete picture of the nature of the stars' activity and examine the correlations between stellar brightness and chromospheric activity, we have started a complimentary campaign of photometric monitoring of these targets in Johnson B, V, and R, Stromgren v and H-alpha, with the use of a small robotic telescope dedicated to this project. This poster will present some results from the first year of photometric monitoring, focusing on the correlations between the photometric bands, and between the photometric and spectroscopic data, as well as an investigation of short-term (1-2 minutes) spectroscopic variations using data obtained earlier this year on the 1.8 m Vatican Advanced Technology Telescope (VATT).

  2. Photometric Observation and Light Curve Analysis of Binary System ...

    Indian Academy of Sciences (India)

    Abstract. Photometric observations of the over-contact binary ER ORI were performed during November 2007 and February to April 2008 with the 51cm telescope of Biruni Observatory of Shiraz University in U, B and V filters (Johnson system) and an RCA 4509 photomultiplier. We used these data to obtain the light curves ...

  3. On the Photometric Error Calibration for the Differential Light Curves ...

    Indian Academy of Sciences (India)

    a value of 1.75 was estimated using the DLCs derived for pairs of steady stars ... apparently steady comparison stars present on the same CCD frame. ...... (2)) on the 262 steady star–star DLCs after accounting for the photometric error.

  4. Dopamine transporters govern diurnal variation in extracellular dopamine tone

    OpenAIRE

    Ferris, Mark J.; España, Rodrigo A.; Locke, Jason L.; Konstantopoulos, Joanne K.; Rose, Jamie H.; Chen, Rong; Jones, Sara R.

    2014-01-01

    The mechanism for diurnal (i.e., light/dark) oscillations in extracellular dopamine tone in mesolimbic and nigrostriatal systems is unknown. This is because, unlike other neurotransmitter systems, variation in dopamine tone does not correlate with variation in dopamine cell firing. The current research pinpoints the dopamine transporter as a critical governor of diurnal variation in both extracellular dopamine tone and the intracellular availability of releasable dopamine. These data describe...

  5. 21 CFR 862.2160 - Discrete photometric chemistry analyzer for clinical use.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Discrete photometric chemistry analyzer for... Clinical Laboratory Instruments § 862.2160 Discrete photometric chemistry analyzer for clinical use. (a) Identification. A discrete photometric chemistry analyzer for clinical use is a device intended to duplicate...

  6. Atmospheric diurnal variations observed with GPS radio occultation soundings

    Directory of Open Access Journals (Sweden)

    F. Xie

    2010-07-01

    Full Text Available The diurnal variation, driven by solar forcing, is a fundamental mode in the Earth's weather and climate system. Radio occultation (RO measurements from the six COSMIC satellites (Constellation Observing System for Meteorology, Ionosphere and Climate provide nearly uniform global coverage with high vertical resolution, all-weather and diurnal sampling capability. This paper analyzes the diurnal variations of temperature and refractivity from three-year (2007–2009 COSMIC RO measurements in the troposphere and stratosphere between 30° S and 30° N. The RO observations reveal both propagating and trapped vertical structures of diurnal variations, including transition regions near the tropopause where data with high vertical resolution are critical. In the tropics the diurnal amplitude in refractivity shows the minimum around 14 km and increases to a local maximum around 32 km in the stratosphere. The upward propagating component of the migrating diurnal tides in the tropics is clearly captured by the GPS RO measurements, which show a downward progression in phase from stratopause to the upper troposphere with a vertical wavelength of about 25 km. At ~32 km the seasonal variation of the tidal amplitude maximizes at the opposite side of the equator relative to the solar forcing. The vertical structure of tidal amplitude shows strong seasonal variations and becomes asymmetric along the equator and tilted toward the summer hemisphere in the solstice months. Such asymmetry becomes less prominent in equinox months.

  7. PHOTOMETRIC SUPERNOVA COSMOLOGY WITH BEAMS AND SDSS-II

    Energy Technology Data Exchange (ETDEWEB)

    Hlozek, Renee [Oxford Astrophysics, Department of Physics, University of Oxford, Keble Road, Oxford, OX1 3RH (United Kingdom); Kunz, Martin [Department de physique theorique, Universite de Geneve, 30, quai Ernest-Ansermet, CH-1211 Geneve 4 (Switzerland); Bassett, Bruce; Smith, Mat; Newling, James [African Institute for Mathematical Sciences, 68 Melrose Road, Muizenberg 7945 (South Africa); Varughese, Melvin [Department of Mathematics and Applied Mathematics, University of Cape Town, Rondebosch, Cape Town, 7700 (South Africa); Kessler, Rick; Frieman, Joshua [The Kavli Institute for Cosmological Physics, The University of Chicago, 933 East 56th Street, Chicago, IL 60637 (United States); Bernstein, Joseph P.; Kuhlmann, Steve; Marriner, John [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL 60439 (United States); Campbell, Heather; Lampeitl, Hubert; Nichol, Robert C. [Institute of Cosmology and Gravitation, Dennis Sciama Building Burnaby Road Portsmouth PO1 3FX (United Kingdom); Dilday, Ben [Las Cumbres Observatory Global Telescope Network, 6740 Cortona Drive, Suite 102, Goleta, CA 93117 (United States); Falck, Bridget; Riess, Adam G. [Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States); Sako, Masao [Department of Physics and Astronomy, University of Pennsylvania, 203 South 33rd Street, Philadelphia, PA 19104 (United States); Schneider, Donald P., E-mail: rhlozek@astro.princeton.edu [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)

    2012-06-20

    Supernova (SN) cosmology without spectroscopic confirmation is an exciting new frontier, which we address here with the Bayesian Estimation Applied to Multiple Species (BEAMS) algorithm and the full three years of data from the Sloan Digital Sky Survey II Supernova Survey (SDSS-II SN). BEAMS is a Bayesian framework for using data from multiple species in statistical inference when one has the probability that each data point belongs to a given species, corresponding in this context to different types of SNe with their probabilities derived from their multi-band light curves. We run the BEAMS algorithm on both Gaussian and more realistic SNANA simulations with of order 10{sup 4} SNe, testing the algorithm against various pitfalls one might expect in the new and somewhat uncharted territory of photometric SN cosmology. We compare the performance of BEAMS to that of both mock spectroscopic surveys and photometric samples that have been cut using typical selection criteria. The latter typically either are biased due to contamination or have significantly larger contours in the cosmological parameters due to small data sets. We then apply BEAMS to the 792 SDSS-II photometric SNe with host spectroscopic redshifts. In this case, BEAMS reduces the area of the {Omega}{sub m}, {Omega}{sub {Lambda}} contours by a factor of three relative to the case where only spectroscopically confirmed data are used (297 SNe). In the case of flatness, the constraints obtained on the matter density applying BEAMS to the photometric SDSS-II data are {Omega}{sup BEAMS}{sub m} = 0.194 {+-} 0.07. This illustrates the potential power of BEAMS for future large photometric SN surveys such as Large Synoptic Survey Telescope.

  8. PHOTOMETRIC SUPERNOVA COSMOLOGY WITH BEAMS AND SDSS-II

    International Nuclear Information System (INIS)

    Hlozek, Renée; Kunz, Martin; Bassett, Bruce; Smith, Mat; Newling, James; Varughese, Melvin; Kessler, Rick; Frieman, Joshua; Bernstein, Joseph P.; Kuhlmann, Steve; Marriner, John; Campbell, Heather; Lampeitl, Hubert; Nichol, Robert C.; Dilday, Ben; Falck, Bridget; Riess, Adam G.; Sako, Masao; Schneider, Donald P.

    2012-01-01

    Supernova (SN) cosmology without spectroscopic confirmation is an exciting new frontier, which we address here with the Bayesian Estimation Applied to Multiple Species (BEAMS) algorithm and the full three years of data from the Sloan Digital Sky Survey II Supernova Survey (SDSS-II SN). BEAMS is a Bayesian framework for using data from multiple species in statistical inference when one has the probability that each data point belongs to a given species, corresponding in this context to different types of SNe with their probabilities derived from their multi-band light curves. We run the BEAMS algorithm on both Gaussian and more realistic SNANA simulations with of order 10 4 SNe, testing the algorithm against various pitfalls one might expect in the new and somewhat uncharted territory of photometric SN cosmology. We compare the performance of BEAMS to that of both mock spectroscopic surveys and photometric samples that have been cut using typical selection criteria. The latter typically either are biased due to contamination or have significantly larger contours in the cosmological parameters due to small data sets. We then apply BEAMS to the 792 SDSS-II photometric SNe with host spectroscopic redshifts. In this case, BEAMS reduces the area of the Ω m , Ω Λ contours by a factor of three relative to the case where only spectroscopically confirmed data are used (297 SNe). In the case of flatness, the constraints obtained on the matter density applying BEAMS to the photometric SDSS-II data are Ω BEAMS m = 0.194 ± 0.07. This illustrates the potential power of BEAMS for future large photometric SN surveys such as Large Synoptic Survey Telescope.

  9. A COMPREHENSIVE PHOTOMETRIC STUDY OF THE CONTACT BINARY GN BOO WITH POSSIBLE MAGNETIC ACTIVITIES

    International Nuclear Information System (INIS)

    Wang, J. J.; Qian, S. B.; Zhang, J.; He, J. J.; Zhao, E. G.; Zhu, L. Y.; Liao, W. P.; Liu, L.; Zhang, Y. P.

    2015-01-01

    Multi-color photometric data of GN Boo observed from 2010 to 2013 are presented. The intrinsic variations of the light curves are remarkable, and their phenomena are probable evidence of stronger magnetic activities on the surfaces of the components. Based on all CCD times of minimum light, a secular increase superimposed on a cyclic oscillation is found. The orbital period increases at a rate of dP/dt = +1.74 × 10 −7 days yr −1 , which can be explained by mass transfer from the less massive component to the more massive one. The period and amplitude of the cyclic variation are P = 9.5632 yr and A = 0.0046 days, respectively, which correspond to the previous published results. Using the 2010 version of the W–D code, five sets of photometric solutions were derived from our new data. The results imply that the stellar spot, the degree of fill-out, and the temperature difference ΔT between the components of GN Boo are variable. It is inferred that the magnetic activities perhaps influence the outer radius of the component, causing the temperature of the component star and the level of contact to change

  10. Spectral and photometric studies of the polar USNO-A2.0 0825-18396733

    Science.gov (United States)

    Gabdeev, M. M.; Borisov, N. V.; Shimansky, V. V.; Spiridonova, O. I.

    2015-03-01

    Results of photometric and spectral studies of the new magnetic cataclysmic variable (polar) USNO-A2.0 0825-18396733 are presented. Photometric data in the B, V, and R c filters show that this object exhibits a red excess of R c - V = 1 m . A red continuum with superposed strong single-peaked Balmer emission lines and HeII λ4686 Å emission, weak lines of neutral helium, and lines of heavy elements are observed in the object's spectra. Doppler maps constructed using the hydrogen and ionized-helium lines indicate that these lines form near the inner Lagrangian point, and that their formation is associated with an accretion stream. The spectra and radial-velocity curves indicate the eclipse of the white dwarf in the system to be partial. Radial-velocity curves derived for emission lines are used to estimate the component masses. The mass of the white dwarf is estimated to be 0.71-0.78 M ⊙, and the mass of the red dwarf to be 0.18-0.20 M ⊙.

  11. Diurnal variations of summertime precipitation over the Tibetan Plateau in relation to orographically-induced regional circulations

    International Nuclear Information System (INIS)

    Liu Xiaodong; Bai Aijuan; Liu Changhai

    2009-01-01

    The diurnal patterns of variation of summertime precipitation over the Tibetan Plateau were first investigated using the TRMM multi-satellite precipitation analysis product for five summer seasons (i.e. June to August for 2002-2006). Both hourly precipitation amount and precipitation frequency exhibit pronounced daily variability with an overall late-afternoon-evening maximum and a dominant morning minimum. A notable exception is the prevalent nocturnal maximum around the periphery of the Plateau. In terms of the normalized harmonic amplitude, the diurnal signal shows significant regional contrast with the strongest manifestation over the central Plateau and the weakest near the periphery. This remarkable spatial dependence in daily rainfall cycles is clear evidence of orographic and heterogeneous land-surface impacts on convective development. Using six-hourly NCEP FNL data, we then examined the diurnal variability in the atmospheric circulation and thermodynamics in this region. The results show that the Plateau heats (cools) the overlying atmosphere during the day (night) more than the surrounding areas, and as a consequence a relatively stronger confluent circulation in this region occurs during the day than during the night, consistent with the diurnal rainfall cycles. Moreover, the regions with large low-level convergence and upper-level divergence correspond to the strong diurnal rainfall variations. The reversed daily alterations of convergence-divergence patterns in the vicinity of the Plateau edges are in agreement with the observed nighttime rainfall peak therein. This study further demonstrates the importance of the Tibetan Plateau in regulating regional circulation and precipitation.

  12. Evaluating the performance of ENVI-met model in diurnal cycles for different meteorological conditions

    Science.gov (United States)

    Acero, Juan A.; Arrizabalaga, Jon

    2018-01-01

    Urban areas are known to modify meteorological variables producing important differences in small spatial scales (i.e. microscale). These affect human thermal comfort conditions and the dispersion of pollutants, especially those emitted inside the urban area, which finally influence quality of life and the use of public open spaces. In this study, the diurnal evolution of meteorological variables measured in four urban spaces is compared with the results provided by ENVI-met (v 4.0). Measurements were carried out during 3 days with different meteorological conditions in Bilbao in the north of the Iberian Peninsula. The evaluation of the model accuracy (i.e. the degree to which modelled values approach measured values) was carried out with several quantitative difference metrics. The results for air temperature and humidity show a good agreement of measured and modelled values independently of the regional meteorological conditions. However, in the case of mean radiant temperature and wind speed, relevant differences are encountered highlighting the limitation of the model to estimate these meteorological variables precisely during diurnal cycles, in the considered evaluation conditions (sites and weather).

  13. A combined stochastic analysis of mean daily temperature and diurnal temperature range

    Science.gov (United States)

    Sirangelo, B.; Caloiero, T.; Coscarelli, R.; Ferrari, E.

    2018-03-01

    In this paper, a stochastic model, previously proposed for the maximum daily temperature, has been improved for the combined analysis of mean daily temperature and diurnal temperature range. In particular, the procedure applied to each variable sequentially performs the deseasonalization, by means of truncated Fourier series expansions, and the normalization of the temperature data, with the use of proper transformation functions. Then, a joint stochastic analysis of both the climatic variables has been performed by means of a FARIMA model, taking into account the stochastic dependency between the variables, namely introducing a cross-correlation between the standardized noises. The model has been applied to five daily temperature series of southern Italy. After the application of a Monte Carlo simulation procedure, the return periods of the joint behavior of the mean daily temperature and the diurnal temperature range have been evaluated. Moreover, the annual maxima of the temperature excursions in consecutive days have been analyzed for the synthetic series. The results obtained showed different behaviors probably linked to the distance from the sea and to the latitude of the station.

  14. THE PHOTOMETRIC CLASSIFICATION SERVER FOR Pan-STARRS1

    International Nuclear Information System (INIS)

    Saglia, R. P.; Bender, R.; Seitz, S.; Senger, R.; Snigula, J.; Phleps, S.; Wilman, D.; Tonry, J. L.; Burgett, W. S.; Chambers, K. C.; Heasley, J. N.; Kaiser, N.; Magnier, E. A.; Morgan, J. S.; Greisel, N.; Bailer-Jones, C. A. L.; Klement, R. J.; Rix, H.-W.; Smith, K.; Green, P. J.

    2012-01-01

    The Pan-STARRS1 survey is obtaining multi-epoch imaging in five bands (g P1 r P1 i P1 z P1 y P1 ) over the entire sky north of declination –30 deg. We describe here the implementation of the Photometric Classification Server (PCS) for Pan-STARRS1. PCS will allow the automatic classification of objects into star/galaxy/quasar classes based on colors and the measurement of photometric redshifts for extragalactic objects, and will constrain stellar parameters for stellar objects, working at the catalog level. We present tests of the system based on high signal-to-noise photometry derived from the Medium-Deep Fields of Pan-STARRS1, using available spectroscopic surveys as training and/or verification sets. We show that the Pan-STARRS1 photometry delivers classifications and photometric redshifts as good as the Sloan Digital Sky Survey (SDSS) photometry to the same magnitude limits. In particular, our preliminary results, based on this relatively limited data set down to the SDSS spectroscopic limits, and therefore potentially improvable, show that stars are correctly classified as such in 85% of cases, galaxies in 97%, and QSOs in 84%. False positives are less than 1% for galaxies, ≈19% for stars, and ≈28% for QSOs. Moreover, photometric redshifts for 1000 luminous red galaxies up to redshift 0.5 are determined to 2.4% precision (defined as 1.48 × Median|z phot – z spec |/(1 + z)) with just 0.4% catastrophic outliers and small (–0.5%) residual bias. For bluer galaxies up to the same redshift, the residual bias (on average –0.5%) trend, percentage of catastrophic failures (1.2%), and precision (4.2%) are higher, but still interestingly small for many science applications. Good photometric redshifts (to 5%) can be obtained for at most 60% of the QSOs of the sample. PCS will create a value-added catalog with classifications and photometric redshifts for eventually many millions of sources.

  15. A photometric study of NGC 2419

    International Nuclear Information System (INIS)

    Racine, R.; Harris, W.E.

    1975-01-01

    Photometry to V=22.2 and B=23.7 is reported for the outer-halo globular cluster NGC 2419. The color-magnitude diagram of the cluster is similar to that of the classic metal-poor cluster M92, and indicates a very low metallicity Zapprox. =1.5times10/sup -4/. The reddening E (B-V) is 0.03plus-or-minus0.01 mag, and the apparent distance modulus is (m-M)/subv/=19.87plus-or-minus0.09, leading to a galactocentric distance of R/subg/=100plus-or-minus5 kpc. The RR Lyrae nature of the numerous short-period variables discovered by Baade is confirmed; of the five known brighter variables, one appears to be a population II Cepheid, while the others fall near the tip of the red giant branch. Attention is drawn to a significant gap in the giant branch. The cluster's age is estimated as T=11.0plus-or-minus0.5times10 9 yr from its HB morphology, or T=11.9plus-or-minus0.3times10 9 yr from a discussion of its galactic orbit. The galactic orbit of NGC 2419 is determined. The cluster is gravitationally bound to the Galaxy, traveling on an orbit of eccentricity 0.62 with a period of 3.4X10 9 yr, and is presently near its apogalaction. It is argued that the cluster was born close to its perigalacticon distance of 24 kpc. A possible gravitational encounter between NGC 2419 and the Magellanic Clouds is mentioned briefly. Finally it is shown that NGC 2419, like clusters with the largest h are among the metals poorest

  16. Specific diurnal EMG activity pattern observed in occlusal collapse patients: relationship between diurnal bruxism and tooth loss progression.

    Directory of Open Access Journals (Sweden)

    Shigehisa Kawakami

    Full Text Available AIM: The role of parafunctional masticatory muscle activity in tooth loss has not been fully clarified. This study aimed to reveal the characteristic activity of masseter muscles in bite collapse patients while awake and asleep. MATERIALS AND METHODS: Six progressive bite collapse patients (PBC group, six age- and gender-matched control subjects (MC group, and six young control subjects (YC group were enrolled. Electromyograms (EMG of the masseter muscles were continuously recorded with an ambulatory EMG recorder while patients were awake and asleep. Diurnal and nocturnal parafunctional EMG activity was classified as phasic, tonic, or mixed using an EMG threshold of 20% maximal voluntary clenching. RESULTS: Highly extended diurnal phasic activity was observed only in the PBC group. The three groups had significantly different mean diurnal phasic episodes per hour, with 13.29±7.18 per hour in the PBC group, 0.95±0.97 per hour in the MC group, and 0.87±0.98 per hour in the YC group (p<0.01. ROC curve analysis suggested that the number of diurnal phasic episodes might be used to predict bite collapsing tooth loss. CONCLUSION: Extensive bite loss might be related to diurnal masticatory muscle parafunction but not to parafunction during sleep. CLINICAL RELEVANCE SCIENTIFIC RATIONALE FOR STUDY: Although mandibular parafunction has been implicated in stomatognathic system breakdown, a causal relationship has not been established because scientific modalities to evaluate parafunctional activity have been lacking. PRINCIPAL FINDINGS: This study used a newly developed EMG recording system that evaluates masseter muscle activity throughout the day. Our results challenge the stereotypical idea of nocturnal bruxism as a strong destructive force. We found that diurnal phasic masticatory muscle activity was most characteristic in patients with progressive bite collapse. PRACTICAL IMPLICATIONS: The incidence of diurnal phasic contractions could be used for

  17. Progress in Research on Diurnal and Semidiurnal Earth Rotation Change

    Science.gov (United States)

    Xu, Xueqing

    2015-08-01

    We mainly focus on the progress of research on high frequency changes in the earth rotation. Firstly, we review the development course and main motivating factors of the diurnal and semidiurnal earth rotation change. In recent decades, earth orientation has been monitored with increasing accuracy by advanced space-geodetic techniques, including lunar and satellite laser ranging, very long baseline interferometry and the global positioning system. We are able to obtain the Earth Rotation Parameters (ERP, polar motion and rotation rate changes) by even 1 to 2 hours observation data, form which obvious diurnal and semidiurnal signals can be detected, and compare them with the predicted results by the ocean model. Both the amplitude and phase are in good agreement in the main diurnal and semidiurnal wave frequency, especially for the UT1, whose compliance is 90%, and 60% for polar motion, there are 30% motivating factor of the diurnal and semidiurnal polar motion have not been identified. Then we comprehensively review the different types of global ocean tidal correction models since the last eighties century, as well as the application research on diurnal and semidiurnal polar motion and UT1, the current ocean tidal correction models have 10% to 20% uncertainty, and need for further refinement.

  18. Diurnal cortisol after early institutional care—Age matters

    Directory of Open Access Journals (Sweden)

    Jessica E. Flannery

    2017-06-01

    Full Text Available Several studies have shown that young children who have experienced early caregiving adversity (e.g. previously institutionalization (PI exhibit flattened diurnal cortisol slopes; however, less is known about how these patterns might differ between children and adolescents, since the transition between childhood and adolescence is a time of purported plasticity in the hypothalamic-pituitary-adrenal (HPA axis. PI youth experience a massive improvement in caregiving environment once adopted into families; therefore we anticipated that a developmental increase in HPA axis plasticity during adolescence might additionally allow for an enhanced enrichment effect by the adoptive family. In a cross-sectional sample of 197 youths (PI and Comparison; 4–15 years old we observed age-related group differences in diurnal slope. First replicating previous findings, PI children exhibited flattened diurnal slope. This group difference, however, was not observed in adolescents. Moderation analyses showed that pubertal development, increased time with family, and early adoption contributed to the steeper diurnal cortisol slope in PI adolescents. These findings add support to existing theories positing that the transition between middle childhood and adolescence may mark an additional sensitive period for diurnal cortisol patterning, allowing PI youth to benefit from the enriched environment provided by adoptive parents during this period of development.

  19. A Photometric Machine-Learning Method to Infer Stellar Metallicity

    Science.gov (United States)

    Miller, Adam A.

    2015-01-01

    Following its formation, a star's metal content is one of the few factors that can significantly alter its evolution. Measurements of stellar metallicity ([Fe/H]) typically require a spectrum, but spectroscopic surveys are limited to a few x 10(exp 6) targets; photometric surveys, on the other hand, have detected > 10(exp 9) stars. I present a new machine-learning method to predict [Fe/H] from photometric colors measured by the Sloan Digital Sky Survey (SDSS). The training set consists of approx. 120,000 stars with SDSS photometry and reliable [Fe/H] measurements from the SEGUE Stellar Parameters Pipeline (SSPP). For bright stars (g' learning method is similar to the scatter in [Fe/H] measurements from low-resolution spectra..

  20. Selective extraction-photometric determination of cadmium by basic dyes

    Energy Technology Data Exchange (ETDEWEB)

    Kish, P P; Balog, J S [Uzhgorodskij Gosudarstvennyj Univ. (Ukrainian SSR)

    1979-12-01

    Two variants of selective extraction-photometric determination of cadmium with basic dyes have been developed. In the first one, cadmium is extracted as the iodide by a tributyl phosphate solution in benzene from aqueous solutions containing 0.1 M KI (pH 6-10). Then the cadmium is transformed into a coloured ion associate by treatment of the extracts with Malachite Green in the presence of iodide ions. In the second case, the extract is equilibrated with an equeous solutions of Rhodamine B in the presence of KBr. In this variant, the cadmium is transformed into an anionic iodide-bromide complex which reacts with Rhodamine B cations to form an ion associate. Procedures have been developed of selective extraction-photometric determination of cadmium in sulphur, indium-gallium and zinc concentrates, Zn-As-Cd-Se and Zn-As-Cd-Te films, Cd-S-In and Ga-Sb-Cd-Te alloys.

  1. A Photometric Machine-Learning Method to Infer Stellar Metallicity

    Science.gov (United States)

    Miller, Adam A.

    2015-01-01

    Following its formation, a star's metal content is one of the few factors that can significantly alter its evolution. Measurements of stellar metallicity ([Fe/H]) typically require a spectrum, but spectroscopic surveys are limited to a few x 10(exp 6) targets; photometric surveys, on the other hand, have detected > 10(exp 9) stars. I present a new machine-learning method to predict [Fe/H] from photometric colors measured by the Sloan Digital Sky Survey (SDSS). The training set consists of approx. 120,000 stars with SDSS photometry and reliable [Fe/H] measurements from the SEGUE Stellar Parameters Pipeline (SSPP). For bright stars (g' machine-learning method is similar to the scatter in [Fe/H] measurements from low-resolution spectra..

  2. Photometric study of the pulsating, eclipsing binary OO DRA

    International Nuclear Information System (INIS)

    Zhang, X. B.; Deng, L. C.; Tian, J. F.; Wang, K.; Yan, Z. Z.; Luo, C. Q.; Sun, J. J.; Liu, Q. L.; Xin, H. Q.; Zhou, Q.; Luo, Z. Q.

    2014-01-01

    We present a comprehensive photometric study of the pulsating, eclipsing binary OO Dra. Simultaneous B- and V-band photometry of the star was carried out on 14 nights. A revised orbital period and a new ephemeris were derived from the data. The first photometric solution of the binary system and the physical parameters of the component stars are determined. They reveal that OO Dra could be a detached system with a less-massive secondary component nearly filling its Roche lobe. By subtracting the eclipsing light changes from the data, we obtained the intrinsic pulsating light curves of the hotter, massive primary component. A frequency analysis of the residual light yields two confident pulsation modes in both B- and V-band data with the dominant frequency detected at 41.865 c/d. A brief discussion concerning the evolutionary status and the pulsation nature of the binary system is finally given.

  3. Physical characterization of asteroid surfaces from photometric analysis

    International Nuclear Information System (INIS)

    Helfenstein, P.; Veverka, J.

    1989-01-01

    Rigorous photometric models, like Hapke's equation, can be applied to the analysis of disk-integrated phase curves in order to estimate a variety of regolith physical properties (average particle single-scattering albedo, particle transparency, soil compaction and large-scale roughness). Unfortunately, unambiguous interpretation is difficult due to uncertainties introduced by the irregular shapes of many asteroids and because Earth-based observations are often restricted to small phase angles (<30 degrees). In this chapter, the authors explore in detail how incomplete phase-angle coverage and nonsphericity of asteroids limits the reliable determination of Hapke's photometric parameters from asteroid phase curves. From obtainable Earth-based observations, it is possible to derive useful relative comparisons of single-scattering albedos, opposition-surge amplitudes, and regolith compaction states for different asteroids

  4. An optrode for photometric detection of ammonia in air

    Science.gov (United States)

    Buzanovskii, V. A.

    2017-10-01

    A scheme of constructing an LED optrode for photometric detection of ammonia in air is considered. The components of the device are (1) a glass plate coated with a film of polydimethylsiloxane with an ion-coupled cation of brilliant-green dye, (2) an LED emitting at a wavelength of 655 nm, and (3) a metal housing. The nominal static conversion function, sensitivity, and relative measurement error of the device are analyzed on the basis of mathematical modeling. The obtained results allow one to design an LED optrode capable of carrying out control for automated technological processes, solving problems in the area of security, etc. The device provides the ability to create photometric gas analyzers of ammonia with small overall dimensions, power consumption, and cost.

  5. MYRaf: A new Approach with IRAF for Astronomical Photometric Reduction

    Science.gov (United States)

    Kilic, Y.; Shameoni Niaei, M.; Özeren, F. F.; Yesilyaprak, C.

    2016-12-01

    In this study, the design and some developments of MYRaf software for astronomical photometric reduction are presented. MYRaf software is an easy to use, reliable, and has a fast IRAF aperture photometry GUI tools. MYRaf software is an important step for the automated software process of robotic telescopes, and uses IRAF, PyRAF, matplotlib, ginga, alipy, and Sextractor with the general-purpose and high-level programming language Python and uses the QT framework.

  6. Photometric classification and redshift estimation of LSST Supernovae

    Science.gov (United States)

    Dai, Mi; Kuhlmann, Steve; Wang, Yun; Kovacs, Eve

    2018-04-01

    Supernova (SN) classification and redshift estimation using photometric data only have become very important for the Large Synoptic Survey Telescope (LSST), given the large number of SNe that LSST will observe and the impossibility of spectroscopically following up all the SNe. We investigate the performance of a SN classifier that uses SN colors to classify LSST SNe with the Random Forest classification algorithm. Our classifier results in an AUC of 0.98 which represents excellent classification. We are able to obtain a photometric SN sample containing 99% SNe Ia by choosing a probability threshold. We estimate the photometric redshifts (photo-z) of SNe in our sample by fitting the SN light curves using the SALT2 model with nested sampling. We obtain a mean bias () of 0.012 with σ ( z_phot-z_spec/1+z_spec) = 0.0294 without using a host-galaxy photo-z prior, and a mean bias () of 0.0017 with σ ( z_phot-z_spec/1+z_spec) = 0.0116 using a host-galaxy photo-z prior. Assuming a flat ΛCDM model with Ωm = 0.3, we obtain Ωm of 0.305 ± 0.008 (statistical errors only), using the simulated LSST sample of photometric SNe Ia (with intrinsic scatter σint = 0.11) derived using our methodology without using host-galaxy photo-z prior. Our method will help boost the power of SNe from the LSST as cosmological probes.

  7. Low-Cost Photometric Calibration for Interactive Relighting

    OpenAIRE

    Loscos , Céline; Drettakis , George

    2000-01-01

    International audience; Computer augmented reality is a rapidly emerging field allowing users to mix virtual and real worlds. Our interest is to allow relighting and remodelling of real scenes, using a reflectance estimation method. Most previous work focused on the quality of the results without considering the expense in computation and the price of acquisition equipment. In this paper, we present a low–cost photometric calibration method which improves the reflectance estimate of real scen...

  8. Extractive photometric determination of zirconium in magnetic alloys

    International Nuclear Information System (INIS)

    Kutyrev, I.M.; Chernysheva, G.M.; Basargin, N.N.; Mikheev, N.I.

    1996-01-01

    A method for extractive photometric determination of Zr in magnetic alloys is presented. Extractive system - trioctylamine in toluene -H 2 SO 4 -Zr ensure selective and rapid (in single extraction) separation of Zr from Fe(3), Fe(2), Co, Ni, Cu, Al, Ti, Cr(3), Mn, Si, P, Nb, and Ta. The reliability of the method is confirmed in determination of Zr in the standerd sample SS 132c

  9. Dynamical and photometric models of star formation in tidal tails

    International Nuclear Information System (INIS)

    Wallin, J.F.

    1990-01-01

    An investigation into the causes of star formation in tidal tails has been conducted using a restricted three-body dynamical model in conjunction with a broadband photometric evolutionary code. Test particles are initially placed in circular orbits around a softened point mass and then perturbed by a companion passing in a parabotic orbit. During the passage, the density evolution of the galaxy is examined both in regions within the disk and in selected comoving regions in the tidal features. Even without the inclusion of self-gravity and hydrodynamics, regions of compression form inside the disk, along the tidal tail, and in the tidal bridge causing local density increases of up to 500 percent. By assuming that the density changes relate to the star-formation rate via a Schmidt (1959) law, limits on the density changes needed to make detectable changes in the colors are calculated. A spiral galaxy population is synthesized and the effects of modest changes in the star-formation rate are explored using a broadband photometric evolutionary code. Density changes similar to those found in the dynamical models will cause detectable changes in the colors of a stellar population. From these models, it is determined that the blue colors and knotty features observed in the tidal features of some galaxies result from increased rates of star formation induced by tidally produced density increases. Limitations of this model are discussed along with photometric evolutionary models based on the density evolution in the tails. 52 refs

  10. ArborZ: PHOTOMETRIC REDSHIFTS USING BOOSTED DECISION TREES

    International Nuclear Information System (INIS)

    Gerdes, David W.; Sypniewski, Adam J.; McKay, Timothy A.; Hao, Jiangang; Weis, Matthew R.; Wechsler, Risa H.; Busha, Michael T.

    2010-01-01

    Precision photometric redshifts will be essential for extracting cosmological parameters from the next generation of wide-area imaging surveys. In this paper, we introduce a photometric redshift algorithm, ArborZ, based on the machine-learning technique of boosted decision trees. We study the algorithm using galaxies from the Sloan Digital Sky Survey (SDSS) and from mock catalogs intended to simulate both the SDSS and the upcoming Dark Energy Survey. We show that it improves upon the performance of existing algorithms. Moreover, the method naturally leads to the reconstruction of a full probability density function (PDF) for the photometric redshift of each galaxy, not merely a single 'best estimate' and error, and also provides a photo-z quality figure of merit for each galaxy that can be used to reject outliers. We show that the stacked PDFs yield a more accurate reconstruction of the redshift distribution N(z). We discuss limitations of the current algorithm and ideas for future work.

  11. Photometric Calibration of the SPRED at the FTU Tokamak

    International Nuclear Information System (INIS)

    May, M J

    1999-01-01

    The SPRED spectrometer was photometrically calibrated by using the FTU tokamak plasma and the Grazing Incidence Time Resolving Spectrometer (GRITS) from the Johns Hopkins University [Stratton, Nucl. Fusion, Vol. 24, No. 6, pp. 767-777, 1984]. The photometric calibration of the GRITS spectrometer was transferred to the SPRED [Fonck, R.J., Applied Optics, Vol. 21, No. 12, p. 2115 (1982)] by directly comparing the intensity of bright lines emitted from the FTU tokamak plasma that were simultaneously measured by both spectrometers. The GRITS spectrometer (λ = 10 - 360 (angstrom); Δλ ∼ 0.7 (angstrom)) was photometrically calibrated in the 50 - 360 (angstrom) spectral range at the SURF II synchrotron light source at NIST in Gaithersburg MD in August 1997. The calibration of each SPRED grating was performed separately. These gratings covered the short wavelengths: 100 - 300 (angstrom)(Δλ - 1.4 (angstrom)) and the long wavelengths: 200 - 1800 (angstrom) (Δλ ∼ 7 (angstrom)). This calibration should be accurate until the microchannel plate of the SPRED is exposed to atmospheric pressure. This calibration is similar to the one obtained by Stratton [Stratton, Rev. Sci. Instrum. 57 (8), pp. 204,3 August 1986

  12. Multicolor photometric study of M31 globular clusters

    International Nuclear Information System (INIS)

    Fan Zhou; Ma Jun; Zhou Xu

    2009-01-01

    We present the photometry of 30 globular clusters (GCs) and GC candidates in 15 intermediate-band filters covering the wavelength region from ∼3000 to ∼10000 A using the archival CCD images of M31 observed as part of the Beijing - Arizona - Taiwan - Connecticut (BATC) Multicolor Sky Survey. We transform these intermediate-band photometric data into the photometry in the standard U BV RI broad-bands. These M31 GC candidates are selected from the Revised Bologna Catalog (RBC V.3.5), and most of these candidates do not have any photometric data. Therefore, the presented photometric data are a supplement to the RBC V.3.5. We find that 4 out of 61 GCs and GC candidates in RBC V.3.5 do not show any signal on the BATC images at their locations. By applying a linear fit of the distribution in the color-magnitude diagram of blue GCs and GC candidates using data from the RBC V.3.5, in this study, we find the 'blue-tilt' of blue M31 GCs with a high confidence at 99.95% or 3.47σ for the confirmed GCs, and > 99.99% or 4.87σ for GCs and GC candidates. (research papers)

  13. Infrared and CCD photometric study of spiral galaxies

    International Nuclear Information System (INIS)

    Manousoyannaki, I.

    1986-01-01

    Infrared J (1.2 μm), H (1.6 μm), and K (2.2 μm) photometry is presented for a subsample of galaxies with morphological types of Sc and Sb of the sample types Sc and Sb of the sample by Rubin et al. and one edge-on spiral galaxy. After an overview of the science of infrared photometry, accurate photometric magnitudes are derived via curves of growth that have been computed using a compiled catalogue of galaxies observed in the infrared. The catalogue is presented in Appendix I. The photometric data are used to derive mass to light ratio distribution and the colors for each galaxy. Several correlations of photometric and dynamical quantities are examined and discussed as integral properties of the two morphological types. The main result of this analysis is that the mass to H-light ratio is independent of radius and of H-luminosity and is a good measure of the stellar component of the galaxy. Emphasis is placed on the Tully-Fisher, absolute magnitude vs log (rotational velocity), relation and its application to derive distances of galaxies. The data are used to derive surface brightness distribution profiles and decompose the profiles to spheroidal and disk components. The radial distribution of color in these galaxies is also discussed

  14. A simple micro-photometric method for urinary iodine determination.

    Science.gov (United States)

    Grimm, Gabriele; Lindorfer, Heidelinde; Kieweg, Heidi; Marculescu, Rodrig; Hoffmann, Martha; Gessl, Alois; Sager, Manfred; Bieglmayer, Christian

    2011-10-01

    Urinary iodide concentration (UIC) is useful to evaluate nutritional iodine status. In clinical settings UIC helps to exclude blocking of the thyroid gland by excessive endogenous iodine, if diagnostic or therapeutic administration of radio-iodine is indicated. Therefore, this study established a simple test for the measurement of UIC. UIC was analyzed in urine samples of 200 patients. Samples were pre-treated at 95°C for 45 min with ammonium persulfate in a thermal cycler, followed by a photometric Sandell-Kolthoff reaction (SK) carried out in microtiter plates. For method comparison, UIC was analyzed in 30 samples by inductivity coupled plasma mass spectro-metry (ICP-MS) as a reference method. Incubation conditions were optimized concerning recovery. The photometric test correlated well to the reference method (SK=0.91*ICP-MS+1, r=0.962) and presented with a functional sensitivity of 20 μg/L. UIC of patient samples ranged from photometric test provides satisfactory results and can be performed with the basic equipment of a clinical laboratory.

  15. Sloan Digital Sky Survey photometric telescope automation and observing software

    International Nuclear Information System (INIS)

    Eric H. Neilsen, Jr.; email = neilsen@fnal.gov

    2002-01-01

    The photometric telescope (PT) provides observations necessary for the photometric calibration of the Sloan Digital Sky Survey (SDSS). Because the attention of the observing staff is occupied by the operation of the 2.5 meter telescope which takes the survey data proper, the PT must reliably take data with little supervision. In this paper we describe the PT's observing program, MOP, which automates most tasks necessary for observing. MOP's automated target selection is closely modeled on the actions a human observer might take, and is built upon a user interface that can be (and has been) used for manual operation. This results in an interface that makes it easy for an observer to track the activities of the automating procedures and intervene with minimum disturbance when necessary. MOP selects targets from the same list of standard star and calibration fields presented to the user, and chooses standard star fields covering ranges of airmass, color, and time necessary to monitor atmospheric extinction and produce a photometric solution. The software determines when additional standard star fields are unnecessary, and selects survey calibration fields according to availability and priority. Other automated features of MOP, such as maintaining the focus and keeping a night log, are also built around still functional manual interfaces, allowing the observer to be as active in observing as desired; MOP's automated features may be used as tools for manual observing, ignored entirely, or allowed to run the telescope with minimal supervision when taking routine data

  16. A PHOTOMETRIC ANALYSIS OF SEVENTEEN BINARY STARS USING SPECKLE IMAGING

    International Nuclear Information System (INIS)

    Davidson, James W.; Baptista, Brian J.; Horch, Elliott P.; Franz, Otto; Van Altena, William F.

    2009-01-01

    Magnitude differences obtained from speckle imaging are used in combination with other data in the literature to place the components of binary star systems on the H-R diagram. Isochrones are compared with the positions obtained, and a best-fit isochrone is determined for each system, yielding both masses of the components as well as an age range consistent with the system parameters. Seventeen systems are studied, 12 of which were observed with the 0.6 m Lowell-Tololo Telescope at Cerro Tololo Inter-American Observatory and six of which were observed with the WIYN 3.5 m Telescope (The WIYN Observatory is a joint facility of the University of Wisconsin-Madison, Indiana University, Yale University, and the National Optical Astronomy Observatories) at Kitt Peak. One system was observed from both sites. In comparing photometric masses to mass information from orbit determinations, we find that the photometric masses agree very well with the dynamical masses, and are generally more precise. For three systems, no dynamical masses exist at present, and therefore the photometrically determined values are the first mass estimates derived for these components.

  17. Derivation of photometric redshifts for the 3XMM catalogue

    Science.gov (United States)

    Georgantopoulos, I.; Corral, A.; Mountrichas, G.; Ruiz, A.; Masoura, V.; Fotopoulou, S.; Watson, M.

    2017-10-01

    We present the results from our ESA Prodex project that aims to derive photometric redshifts for the 3XMM catalogue. The 3XMM DR-6 offers the largest X-ray survey, containing 470,000 unique sources over 1000 sq. degrees. We cross-correlate the X-ray positions with optical and near-IR catalogues using Bayesian statistics. The optical catalogue used so far is the SDSS while currently we are employing the recently released PANSTARRS catalogue. In the near IR we use the Viking, VHS, UKIDS surveys and also the WISE W1 and W2 filters. The estimation of photometric redshifts is based on the TPZ software. The training sample is based on X-ray selected samples with available SDSS spectroscopy. We present here the results for the 40,000 3XMM sources with available SDSS counterparts. Our analysis provides very reliable photometric redshifts with sigma(mad)=0.05 and a fraction of outliers of 8% for the optically extended sources. We discuss the wide range of applications that are feasible using this unprecedented resource.

  18. Seasonal variation in diurnal atmospheric grass pollen concentration profiles

    DEFF Research Database (Denmark)

    Peel, Robert George; Ørby, Pia Viuf; Skjøth, Carsten Ambelas

    2014-01-01

    the time of day when peak concentrations are most likely to occur using seasonally averaged diurnal profiles. Atmospheric pollen loads are highly dependent upon emissions, and different species of grass are known to flower and emit pollen at different times of the day and during different periods......In this study, the diurnal atmospheric grass pollen concentration profile within the Danish city of Aarhus was shown to change in a systematic manner as the pollen season progressed. Although diurnal grass pollen profiles can differ greatly from day-to-day, it is common practice to establish...... of the pollen season. Pollen concentrations are also influenced by meteorological factors - directly through those parameters that govern pollen dispersion and transport, and indirectly through the weather-driven flowering process. We found that three different profiles dominated the grass pollen season...

  19. Specific Diurnal EMG Activity Pattern Observed in Occlusal Collapse Patients: Relationship between Diurnal Bruxism and Tooth Loss Progression

    Science.gov (United States)

    Kawakami, Shigehisa; Kumazaki, Yohei; Manda, Yosuke; Oki, Kazuhiro; Minagi, Shogo

    2014-01-01

    Aim The role of parafunctional masticatory muscle activity in tooth loss has not been fully clarified. This study aimed to reveal the characteristic activity of masseter muscles in bite collapse patients while awake and asleep. Materials and Methods Six progressive bite collapse patients (PBC group), six age- and gender-matched control subjects (MC group), and six young control subjects (YC group) were enrolled. Electromyograms (EMG) of the masseter muscles were continuously recorded with an ambulatory EMG recorder while patients were awake and asleep. Diurnal and nocturnal parafunctional EMG activity was classified as phasic, tonic, or mixed using an EMG threshold of 20% maximal voluntary clenching. Results Highly extended diurnal phasic activity was observed only in the PBC group. The three groups had significantly different mean diurnal phasic episodes per hour, with 13.29±7.18 per hour in the PBC group, 0.95±0.97 per hour in the MC group, and 0.87±0.98 per hour in the YC group (pbruxism as a strong destructive force. We found that diurnal phasic masticatory muscle activity was most characteristic in patients with progressive bite collapse. Practical implications The incidence of diurnal phasic contractions could be used for the prognostic evaluation of stomatognathic system stability. PMID:25010348

  20. Photometric study of an eclipsing binary in the field of M37

    International Nuclear Information System (INIS)

    Priya Devarapalli Shanti; Sriram Kandulapati; Rao Pasagada Vivekananda

    2014-01-01

    CCD photometric observations with B and V passbands were performed on the contact binary V3 in the field of open cluster M37. The solutions were obtained for data from both B and V passbands along with R passband given by Hartman et al. using the Wilson-Devinney code. The positive O'Connell effect was observed in all the three passbands and its associated cool spot parameters were derived. The results indicate that the spot parameters have not shown any significant variability during the last four years. The spot radius was found to be 40° and located close to the equator of the secondary component. The absolute parameters of the system were derived using the empirical relations given by Gazeas et al. (research papers)

  1. Frequency and mode identification of γ Doradus from photometric and spectroscopic observations*

    Science.gov (United States)

    Brunsden, E.; Pollard, K. R.; Wright, D. J.; De Cat, P.; Cottrell, P. L.

    2018-04-01

    The prototype star for the γ Doradus class of pulsating variables was studied employing photometric and spectroscopic observations to determine the frequencies and modes of pulsation. The four frequencies found are self-consistent between the observation types and almost identical to those found in previous studies (1.3641 d-1, 1.8783 d-1, 1.4742 d-1, and 1.3209 d-1). Three of the frequencies are classified as l, m = (1, 1) pulsations and the other is ambiguous between l, m = (2, 0) and (2, -2) modes. Two frequencies are shown to be stable over 20 yr since their first identification. The agreement in ground-based work makes this star an excellent calibrator between high-precision photometry and spectroscopy with the upcoming TESS observations and a potential standard for continued asteroseismic modelling.

  2. Diurnal Salivary Alpha-amylase Dynamics among Dementia Family Caregivers

    Science.gov (United States)

    Liu, Yin; Granger, Douglas A.; Kim, Kyungmin; Klein, Laura C.; Almeida, David M.; Zarit, Steven H.

    2016-01-01

    Objective The study examined diurnal regulation of salivary alpha-amylase (sAA) in association with daily stressors, adult day services (ADS) use, and other caregiving characteristics. Methods A sample of 165 family caregivers of individuals with dementia (IWD) completed an 8-day diary study. Caregivers provided 5 saliva samples across the 8 days. On some days, caregivers provided all or most of the care. On other days, their relative attended ADS for part of the day. A 3-level unconditional linear spline model was fit to describe the typical sAA diurnal rhythms. Predictors were then added to the unconditional model to test the hypotheses on ADS use and daily stressors. Results Daily ADS use did not have an effect on diurnal sAA regulation. However, controlling for daily ADS use, greater ADS use over the 8 days was associated with a more prominent rise between 30 minutes after wake-up and before lunch, and a more prominent decline between before lunch and late afternoon. Fewer ADS days were associated with a more flattened sAA diurnal rhythm. Additionally, greater daily care-related stressor exposures had a within-person association with lower sAA levels in the late afternoon. Care-related stressor exposures had significant within- and between-person associations with sAA diurnal slopes. Furthermore, daily positive experiences had a significant between-person association with sAA diurnal slopes. Conclusions Caring for a disabled family member may heighten the vulnerability to potential physiological conditions. Respite from care stressors from ADS use may have some biobehavioral benefits on sAA regulations. PMID:27786517

  3. EVOLUTION OF GALAXY LUMINOSITY FUNCTION USING PHOTOMETRIC REDSHIFTS

    International Nuclear Information System (INIS)

    Ramos, B. H. F.; Pellegrini, P. S.; Da Costa, L. N.; Maia, M. A. G.; Ogando, R. L. C.; De Simoni, F.; Benoist, C.; Makler, M.; Mesquita, A. A.

    2011-01-01

    We examine the impact of using photometric redshifts for studying the evolution of both the global galaxy luminosity function (LF) and that for different galaxy types. To this end, we compare the LFs obtained using photometric redshifts from the Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) D1 field with those from the spectroscopic survey VIMOS VLT Deep Survey (VVDS) comprising ∼4800 galaxies. We find that for z ≤ 2.0, in the interval of magnitudes considered by this survey, the LFs obtained using photometric and spectroscopic redshifts show a remarkable agreement. This good agreement led us to use all four Deep fields of the CFHTLS comprising ∼386,000 galaxies to compute the LF of the combined fields and directly estimate the error in the parameters based on the field-to-field variation. We find that the characteristic absolute magnitude M* of Schechter fits fades by ∼0.7 mag from z ∼ 1.8 to z ∼ 0.3, while the characteristic density φ* increases by a factor of ∼4 in the same redshift interval. We use the galaxy classification provided by the template fitting program used to compute photometric redshifts and split the sample into galaxy types. We find that these Schechter parameters evolve differently for each galaxy type, an indication that their evolution is a combination of several effects: galaxy merging, star formation quenching, and mass assembly. All these results are compatible with those obtained by different spectroscopic surveys such as VVDS, DEEP2, and zCosmos, which reinforces the fact that photometric redshifts can be used to study galaxy evolution, at least for the redshift bins adopted so far. This is of great interest since future very large imaging surveys containing hundreds of millions of galaxies will allow us to obtain important precise measurements to constrain the evolution of the LF and to explore the dependence of this evolution on morphology and/or color helping constrain the mechanisms of galaxy evolution.

  4. Effects of diurnal temperature range and drought on wheat yield in Spain

    Science.gov (United States)

    Hernandez-Barrera, S.; Rodriguez-Puebla, C.; Challinor, A. J.

    2017-07-01

    This study aims to provide new insight on the wheat yield historical response to climate processes throughout Spain by using statistical methods. Our data includes observed wheat yield, pseudo-observations E-OBS for the period 1979 to 2014, and outputs of general circulation models in phase 5 of the Coupled Models Inter-comparison Project (CMIP5) for the period 1901 to 2099. In investigating the relationship between climate and wheat variability, we have applied the approach known as the partial least-square regression, which captures the relevant climate drivers accounting for variations in wheat yield. We found that drought occurring in autumn and spring and the diurnal range of temperature experienced during the winter are major processes to characterize the wheat yield variability in Spain. These observable climate processes are used for an empirical model that is utilized in assessing the wheat yield trends in Spain under different climate conditions. To isolate the trend within the wheat time series, we implemented the adaptive approach known as Ensemble Empirical Mode Decomposition. Wheat yields in the twenty-first century are experiencing a downward trend that we claim is a consequence of widespread drought over the Iberian Peninsula and an increase in the diurnal range of temperature. These results are important to inform about the wheat vulnerability in this region to coming changes and to develop adaptation strategies.

  5. The diurnal pattern of microwave backscattering by wheat

    International Nuclear Information System (INIS)

    Brisco, B.; Brown, R.J.; Koehler, J.A.; Sofko, G.J.; McKibben, M.J.

    1990-01-01

    A truck-mounted Ku-, C-, and L-band scatterometer system was used to obtain diurnal multiparameter radar backscatter measurements of wheat in August 1987 and June and July 1988. Concurrent field measurements of plant and soil moisture content were made in support of the radar data. Analyses of these data demonstrate the sensitivity of the microwave signals to the daily movement of water in the soil/plant system. The dependence of frequency, incidence angle, and polarization are discussed in relationship to the diurnal and seasonal changes in the soil and plant water content. The results are used to identify potential agronomic applications and future research requirements. (author)

  6. Radiation closure and diurnal cycle of the clear-sky dust instantaneous direct radiative forcing over Arabian Peninsula

    KAUST Repository

    Osipov, Sergey

    2015-04-01

    To better quantify radiative effects of dust over the Arabian Peninsula we have developed a standalone column radiation transport model coupled with the Mie calculations and driven by reanalysis meteorological fields and atmospheric composition. Numerical experiments are carried out for a wide range of aerosol optical depths, including extreme values developed during the dust storm on 18-20 March 2012. Comprehensive ground-based observations and satellite retrievals are used to estimate aerosol optical properties, validate calculations and carry out radiation closure. The broadband surface albedo, fluxes at the bottom and top of the atmosphere as well as instantaneous dust radiative forcing are estimated both from the model and from observations. Diurnal cycle of the the shortwave instantaneous dust direct radiative forcing is studied for a range of aerosol and surface characteristics representative for the Arabian Peninsula. Mechanisms and parameters responsible for diurnal variability of the radiative forcing are evaluated. We found that intrinsic variability of the surface albedo and its dependence on atmospheric conditions along with anisotropic aerosol scattering are mostly responsible for diurnal effects. We also discuss estimates of the climatological dust instantaneous direct radiative forcing over land and the Red Sea using two approaches. The first approach is based on the probability density function of the aerosol optical depth, and the second is based on the climatologically average Spinning Enhanced Visible and Infrared Imager (SEVIRI) aerosol optical depth. Results are compared with Geostationary Earth Radiation Budget (GERB) derived top of the atmosphere climatological forcing over the Red Sea.

  7. Diurnal variation of precipitation over the Carolina Sandhills region

    Indian Academy of Sciences (India)

    State Climate Office of North Carolina, Raleigh, NC 27695-8208, USA. ∗ e-mail: ... of the weather forecast models experience problems in accounting for the ... effect of vegetation and soil contrasts on thermally induced flow is ... Sandhills; diurnal convection; heat flux gradients; cloud–radiation interaction. J. Earth Syst. Sci.

  8. Daytime passerine migrants over the Sahara — are these diurnal ...

    African Journals Online (AJOL)

    The landing tendency (sink rate) correlated negatively with the tail wind component. Transect counts on the ground revealed very low proportions of diurnal migrants, not matching the relatively high densities of passerine migration during the day, and a high correlation between transect density of nocturnal migrants and ...

  9. Factors affecting diurnal stem contraction in young Douglas-fir

    Science.gov (United States)

    Warren D. Devine; Constance Harrington

    2011-01-01

    Diurnal fluctuation in a tree's stem diameter is a function of daily growth and of the tree's water balance, as water is temporarily stored in the relatively elastic outer cambial and phloem tissues. On a very productive site in southwestern Washington, U.S.A we used recording dendrometers to monitor stem diameter fluctuations of Douglas-fir at plantation...

  10. Pathophysiology of diurnal drooling in Parkinson’s disease

    NARCIS (Netherlands)

    Lenie van den Engel-Hoek; Johanna Kalf; Bastiaan Bloem; George Borm; Machiel Zwarts; Bert de Swart; Marten Munneke

    2011-01-01

    Drooling is an incapacitating feature of Parkinson's disease. Better pathophysiological insights are needed to improve treatment. In this study, we tested the hypothesis that the cause of drooling is multifactorial. We examined 15 patients with Parkinson's disease with distinct diurnal saliva loss

  11. diurnal climatic pressure on haematology and blood biochemistry of ...

    African Journals Online (AJOL)

    Twelve 2.5-year-old West African Dward (WAD) sheep consisting of eight (8) ewes and four (4) rams with mean body weight 19.4kg were used to study the effects of diurnal (morning and afternoon) climatic variations on the haematological and biochemical responses in WAD sheep. The animals were randomly assigned to ...

  12. Diurnal Variation in the Basal Emission Rate of Isoprene

    Science.gov (United States)

    Jennifer Funk; Clive G. Jones; Christine J. Baker; Heather M. Fuller; Christian P. Giardina; Manuel T. Lerdua

    2003-01-01

    Isoprene is emitted from numerous plant species and profoundly influences tropospheric chemistry. Due to the short lifetime of isoprene in the atmosphere, developing an understanding of emission patterns at small time scales is essential for modeling regional atmospheric chemistry processes. Previous studies suggest that diurnal fluctuations in isoprene emission may be...

  13. Solar diurnal anisotropy measured using muons in GRAPES-3 ...

    Indian Academy of Sciences (India)

    The mean energy of muons at sea level is ∼4 GeV with a rel- .... of decays of mesons and muons work against each other resulting in temperature coef- ..... The mean muon rate of 16 modules measured every 15 min for one week interval from .... 4. 8. 12. 16. 20. 24. Hours. Figure 12. Solar diurnal anisotropy measured in ...

  14. Diurnal variations of serum erythropoietin at sea level and altitude

    DEFF Research Database (Denmark)

    Klausen, T; Poulsen, T D; Fogh-Andersen, N

    1996-01-01

    in 2, 3 diphosphoglycerate. After 64 h at altitude, six of the nine subjects had down-regulated their serum-EPO concentrations so that median values were three times above those at sea level. These six subjects had significant diurnal variations of serum-EPO concentration at sea level; the nadir...

  15. Differences in ocular parameters between diurnal and nocturnal raptors.

    Science.gov (United States)

    Beckwith-Cohen, Billie; Horowitz, Igal; Bdolah-Abram, Tali; Lublin, Avishai; Ofri, Ron

    2015-01-01

    To establish and compare normal ocular parameters between and within diurnal and nocturnal raptor groups. Eighty-eight ophthalmically normal raptors of six nocturnal and 11 diurnal species were studied. Tear production was measured using Schirmer tear test (STT) and phenol red thread test (PRTT), and applanation tonometry was conducted. Ultrasonographic measurements of axial length (AL), mediolateral axis (ML), vitreous body (VB), and pecten length (PL) were recorded, and conjunctival cultures were obtained. A weak correlation (R = 0.312, P = 0.006) was found between PRTT and STT. Tear production was significantly lower in nocturnal species (P raptors were positive for mycology or bacteriology, either on culture or PCR. The most common infectious agent isolated was Staphylococcus spp. Phenol red thread test and STT are both valid methods to measure tear production; however, a separate baseline must be determined for each species using these methods, as the results of one method cannot be extrapolated to the other. Due to significant differences observed within diurnal and nocturnal species, it appears that a more intricate division should be used when comparing these parameters for raptors, and the classification of diurnal or nocturnal holds little significance in the baseline of these data. © 2013 American College of Veterinary Ophthalmologists.

  16. PHOTOMETRIC MONITORING OF THE COLDEST KNOWN BROWN DWARF WITH THE SPITZER SPACE TELESCOPE

    Energy Technology Data Exchange (ETDEWEB)

    Esplin, T. L.; Luhman, K. L. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Cushing, M. C.; Hardegree-Ullman, K. K.; Trucks, J. L.; Schneider, A. C. [Department of Physics and Astronomy, The University of Toledo, OH 43606 (United States); Burgasser, A. J., E-mail: taran.esplin@psu.edu [Center for Astrophysics and Space Science, University of California San Diego, La Jolla, CA 92093 (United States)

    2016-11-20

    Because WISE J085510.83-071442.5 (hereafter WISE 0855-0714) is the coldest known brown dwarf (∼250 K) and one of the Sun’s closest neighbors (2.2 pc), it offers a unique opportunity to study a planet-like atmosphere in an unexplored regime of temperature. To detect and characterize inhomogeneities in its atmosphere (e.g., patchy clouds, hot spots), we have performed time-series photometric monitoring of WISE 0855-0714 at 3.6 and 4.5 μ m with the Spitzer Space Telescope during two 23 hr periods that were separated by several months. For both bands, we have detected variability with peak-to-peak amplitudes of 4%–5% and 3%–4% in the first and second epochs, respectively. The light curves are semiperiodic in the first epoch for both bands, but they are more irregular in the second epoch. Models of patchy clouds have predicted a large increase in mid-infrared (mid-IR) variability amplitudes (for a given cloud covering fraction) with the appearance of water ice clouds at T {sub eff} < 375 K, so if such clouds are responsible for the variability of WISE 0855-0714, then its small amplitudes of variability indicate a very small deviation in cloud coverage between hemispheres. Alternatively, the similarity in mid-IR variability amplitudes between WISE 0855-0714 and somewhat warmer T and Y dwarfs may suggest that they share a common origin for their variability (i.e., not water clouds). In addition to our variability data, we have examined other constraints on the presence of water ice clouds in the atmosphere of WISE 0855-0714, including the recent mid-IR spectrum from Skemer et al. (2016). We find that robust evidence of such clouds is not yet available.

  17. Dynamic and photometric evolutionary models of tidal tails and ripples

    International Nuclear Information System (INIS)

    Wallin, J.F.

    1989-01-01

    An investigation into the causes of star formation in tidal tails has been conducted using a restricted three-body dynamical model in conjunction with a broad-band photometric evolutionary code. In these models, regions of compression form inside the disk and along the tidal tail and tidal bridge. The effects these density changes have on the colors of the tidal features are examined with a broad-band photometric evolutionary code. A spiral galaxy population is synthesized and the effects of modest changes in the star formation rate are explored. Limits on the density changes needed to make detectable changes in the colors are calculated using a Schmidt (1959) law. These models suggest that the blue colors and knotty features observed in the tidal features of some galaxies result from increased rates of star formation induced by tidally produced density increases. Limitations of this model are discussed along with photometric evolutionary models based on the density evolution in the tails. The Lynds and Toomre (1976) interpretation of ring galaxies as the natural result of a nearly head-on collision between a disk galaxy and a companion galaxy has become widely accepted. Similarly, Quinn's (1984) interpretation of the shells in elliptical galaxies as the aftermath of the cannibalization of a low-mass companion has been quite successful in accounting for the observations. Restricted three-body calculations of high inclination, low impact parameter encounters demonstrate that the shell-like ripples observed in a number of disk galaxies can also be produced as collisional artifacts from internal oscillations much as in ring galaxies

  18. Diurnal variations of indoor radon progeny for Bangalore metropolitan, India

    International Nuclear Information System (INIS)

    Nagesh, V.; Sathish, L.A.; Nagaraja, K.; Sundareshan, S.

    2010-01-01

    Radon progenies are identified as major causes of the lung cancer if the activity is above its normal. It has not been clear whether radon poses a similar risk of causing lung cancer in humans exposed at generally lower levels found in homes, but a number of indoor radon survey have been carried out in recent years around the world. In view of this an attempt has been made for the measurement of diurnal variation of indoor radon levels for the environment of Bangalore metropolitan, India. The Radon progeny concentrations in terms of working level were measured using Kusnetz's method. The patterns of daily and annual changes in indoor Radon concentration have been observed in a general way for many years. However, understanding of the physical basis for these changes had to await the development of continuous monitors and a more complete knowledge of transport processes in the atmosphere. Over a continent, heating of the ground surface by the Sun during the day and cooling by radiation during the night causes a marked diurnal change in temperature near the surface. As a result cool air near the ground will accumulate radon isotopes from surface flux during the night; while during the day the warm air will be transported upward carrying radon with it. Many buildings show diurnal radon variations. Concentrations are relatively higher during night than daytime. This is influenced by the outdoor-indoor temperature contrast. This effect can be enhanced in buildings with strong diurnal use patterns. Buildings that have high average radon concentrations, but are only occupied for part of the day, may need to be measured during occupied periods to determine if there is significant diurnal radon variation. The results are discussed in detail. (author)

  19. Variability in large-scale wind power generation

    DEFF Research Database (Denmark)

    Kiviluoma, Juha; Holttinen, Hannele; Weir, David

    2016-01-01

    The paper demonstrates the characteristics of wind power variability and net load variability in multiple power systems based on real data from multiple years. Demonstrated characteristics include probability distribution for different ramp durations, seasonal and diurnal variability and low net ...... with well-dispersed wind power. Copyright © 2015 John Wiley & Sons, Ltd....

  20. Photometric and emission-spectrometric determination of boron in steels

    International Nuclear Information System (INIS)

    Thierig, D.

    1982-01-01

    A method for the photometric determination of boron in unalloyed and alloyed steels is described, in which Curcumine is used as reagent. A separation of boron is not necessary. Limit of detection: 0.0003% B. The decomposition of boron nitride in the steel is achieved by heating the whole sample in fuming sulphuric acid/phosphoric acid. For the emission spectrometric investigation of solid steel samples and for the spectrochemical analysis of solutions with plasma excitation working parameters are given and possibilities of interferences are demonstrated. (orig.) [de

  1. A photometric map of interstellar reddening within 100 PC

    Science.gov (United States)

    Perry, C. L.; Johnston, L.; Crawford, D. L.

    1982-12-01

    Color excesses and distances are calculated for 300 bright, northern, late F stars using uvby beta photometric indices. The data allow an extension of the earlier maps by Perry and Johnston of the spatial distribution of interstellar reddening into the local (r less than 100 pc) solar neighborhood. Some definite conclusions are made regarding the distribution of interstellar dust in the northern hemisphere and within 300 pc of the sun by merging these results and the polarimetric observations by Tinbergen (1982) for 180 stars within 35 pc of the sun.

  2. Probing dark energy with lensing magnification in photometric surveys.

    Science.gov (United States)

    Schneider, Michael D

    2014-02-14

    I present an estimator for the angular cross correlation of two tracers of the cosmological large-scale structure that utilizes redshift information to isolate separate physical contributions. The estimator is derived by solving the Limber equation for a reweighting of the foreground tracer that nulls either clustering or lensing contributions to the cross correlation function. Applied to future photometric surveys, the estimator can enhance the measurement of gravitational lensing magnification effects to provide a competitive independent constraint on the dark energy equation of state.

  3. Photometric determination of yttrium in zirconium-containing materials

    International Nuclear Information System (INIS)

    Barbina, T.M.; Polezhaev, Yu.M.

    1984-01-01

    Comparative evaluation of the effect of different ways of eliminating the zirconium interfering effect on the results of yttrium photometric determination with arsenazo 2 in artificial mixtures of Y 2 O 3 and ZrO 2 , containing 5 and 10 mol.% Y 2 O 3 , has been carried out. The effect of Zr is eliminated by means of its precipitation by ammonium solution in the form of hydroxide and using camouflaging with 25% sulfosalicylic acid. Both ways do not provide a correct enough result. The use of non-reagent thermohydrolytic Zr precipitation during the analysis of zirconium-containing materials permits to obtain correct and well-reproducible results

  4. Evolution of the clustering of photometrically selected SDSS galaxies

    OpenAIRE

    Ross, Ashley; Percival, Will; Brunner, R.

    2010-01-01

    We measure the angular auto-correlation functions, ω(θ), of Sloan Digital Sky Survey (SDSS) galaxies selected to have photometric redshifts 0.1 < z < 0.4 and absolute r-band magnitudes Mr < −21.2. We split these galaxies into five overlapping redshift shells of width 0.1 and measure ω(θ) in each subsample in order to investigate the evolution of SDSS galaxies. We find that the bias increases substantially with redshift – much more so than one would expect for a passively evolving sample. We u...

  5. Changes in diurnal temperature range and national cereal yields

    Energy Technology Data Exchange (ETDEWEB)

    Lobell, D

    2007-04-26

    Models of yield responses to temperature change have often considered only changes in average temperature (Tavg), with the implicit assumption that changes in the diurnal temperature range (DTR) can safely be ignored. The goal of this study was to evaluate this assumption using a combination of historical datasets and climate model projections. Data on national crop yields for 1961-2002 in the 10 leading producers of wheat, rice, and maize were combined with datasets on climate and crop locations to evaluate the empirical relationships between Tavg, DTR, and crop yields. In several rice and maize growing regions, including the two major nations for each crop, there was a clear negative response of yields to increased DTR. This finding reflects a nonlinear response of yields to temperature, which likely results from greater water and heat stress during hot days. In many other cases, the effects of DTR were not statistically significant, in part because correlations of DTR with other climate variables and the relatively short length of the time series resulted in wide confidence intervals for the estimates. To evaluate whether future changes in DTR are relevant to crop impact assessments, yield responses to projected changes in Tavg and DTR by 2046-2065 from 11 climate models were estimated. The mean climate model projections indicated an increase in DTR in most seasons and locations where wheat is grown, mixed projections for maize, and a general decrease in DTR for rice. These mean projections were associated with wide ranges that included zero in nearly all cases. The estimated impacts of DTR changes on yields were generally small (<5% change in yields) relative to the consistently negative impact of projected warming of Tavg. However, DTR changes did significantly affect yield responses in several cases, such as in reducing US maize yields and increasing India rice yields. Because DTR projections tend to be positively correlated with Tavg, estimates of yields

  6. On the effects of the evolution of microbial mats and land plants on the Earth as a planet. Photometric and spectroscopic light curves of paleo-Earths

    OpenAIRE

    Sanromá, E.; Pallé, E.; García-Muñoz, A.

    2013-01-01

    Understanding the spectral and photometric variability of the Earth and the rest of the solar system planets has become of the utmost importance for the future characterization of rocky exoplanets. As this is not only interesting at present times but also along the planetary evolution, we studied the effect that the evolution of microbial mats and plants over land has had on the way our planet looks from afar. As life evolved, continental surfaces changed gradually and non- uniformly from des...

  7. Water-stress-induced breakdown of carbon-water relations: indicators from diurnal FLUXNET patterns

    Science.gov (United States)

    Nelson, Jacob A.; Carvalhais, Nuno; Migliavacca, Mirco; Reichstein, Markus; Jung, Martin

    2018-04-01

    Understanding of terrestrial carbon and water cycles is currently hampered by an uncertainty in how to capture the large variety of plant responses to drought. In FLUXNET, the global network of CO2 and H2O flux observations, many sites do not uniformly report the ancillary variables needed to study drought response physiology. To this end, we outline two data-driven indicators based on diurnal energy, water, and carbon flux patterns derived directly from the eddy covariance data and based on theorized physiological responses to hydraulic and non-stomatal limitations. Hydraulic limitations (i.e. intra-plant limitations on water movement) are proxied using the relative diurnal centroid (CET*), which measures the degree to which the flux of evapotranspiration (ET) is shifted toward the morning. Non-stomatal limitations (e.g. inhibitions of biochemical reactions, RuBisCO activity, and/or mesophyll conductance) are characterized by the Diurnal Water-Carbon Index (DWCI), which measures the degree of coupling between ET and gross primary productivity (GPP) within each day. As a proof of concept we show the response of the metrics at six European sites during the 2003 heat wave event, showing a varied response of morning shifts and decoupling. Globally, we found indications of hydraulic limitations in the form of significantly high frequencies of morning-shifted days in dry/Mediterranean climates and savanna/evergreen plant functional types (PFTs), whereas high frequencies of decoupling were dominated by dry climates and grassland/savanna PFTs indicating a prevalence of non-stomatal limitations in these ecosystems. Overall, both the diurnal centroid and DWCI were associated with high net radiation and low latent energy typical of drought. Using three water use efficiency (WUE) models, we found the mean differences between expected and observed WUE to be -0.09 to 0.44 µmol mmol-1 and -0.29 to -0.40 µmol mmol-1 for decoupled and morning-shifted days, respectively, compared

  8. Convective Cloud and Rainfall Processes Over the Maritime Continent: Simulation and Analysis of the Diurnal Cycle

    Science.gov (United States)

    Gianotti, Rebecca L.

    The Maritime Continent experiences strong moist convection, which produces significant rainfall and drives large fluxes of heat and moisture to the upper troposphere. Despite the importance of these processes to global circulations, current predictions of climate change over this region are still highly uncertain, largely due to inadequate representation of the diurnally-varying processes related to convection. In this work, a coupled numerical model of the land-atmosphere system (RegCM3-IBIS) is used to investigate how more physically-realistic representations of these processes can be incorporated into large-scale climate models. In particular, this work improves simulations of convective-radiative feedbacks and the role of cumulus clouds in mediating the diurnal cycle of rainfall. Three key contributions are made to the development of RegCM3-IBIS. Two pieces of work relate directly to the formation and dissipation of convective clouds: a new representation of convective cloud cover, and a new parameterization of convective rainfall production. These formulations only contain parameters that can be directly quantified from observational data, are independent of model user choices such as domain size or resolution, and explicitly account for subgrid variability in cloud water content and nonlinearities in rainfall production. The third key piece of work introduces a new method for representation of cloud formation within the boundary layer. A comprehensive evaluation of the improved model was undertaken using a range of satellite-derived and ground-based datasets, including a new dataset from Singapore's Changi airport that documents diurnal variation of the local boundary layer height. The performance of RegCM3-IBIS with the new formulations is greatly improved across all evaluation metrics, including cloud cover, cloud liquid water, radiative fluxes and rainfall, indicating consistent improvement in physical realism throughout the simulation. This work

  9. Spectroscopic and photometric study of the eclipsing interacting binary V495 Centauri

    Science.gov (United States)

    Rosales Guzmán, J. A.; Mennickent, R. E.; Djurašević, G.; Araya, I.; Curé, M.

    2018-05-01

    Double Periodic Variables (DPV) are among the new enigmas of semidetached eclipsing binaries. These are intermediate-mass binaries characterized by a long photometric period lasting on average 33 times the orbital period. We present a spectroscopic and photometric study of the DPV V495 Cen based on new high-resolution spectra and the ASAS V-band light curve. We have determined an improved orbital period of 33.492 ± 0.002 d and a long period of 1283 d. We find a cool evolved star of M2=0.91± 0.2 M_{⊙}, T2 = 6000 ± 250 K and R2=19.3 ± 0.5 R_{⊙} and a hot companion of M1= 5.76± 0.3 M_{⊙}, T1 = 16960 ± 400 K and R=4.5± 0.2 R_{⊙}. The mid-type B dwarf is surrounded by a concave and geometrically thick disc, of radial extension Rd= 40.2± 1.3 R_{⊙} contributing ˜11 per cent to the total luminosity of the system at the V band. The system is seen under inclination 84.8° ± 0.6° and it is at a distance d = 2092 ± 104.6 pc. The light-curve analysis suggests that the mass transfer stream impacts the external edge of the disc forming a hot region 11 per cent hotter than the surrounding disc material. The persistent V < R asymmetry of the Hα emission suggests the presence of a wind and the detection of a secondary absorption component in He I lines indicates a possible wind origin in the hotspot region.

  10. Impact of diurnal temperature fluctuations on larval settlement and growth of the reef coral Pocillopora damicornis

    Science.gov (United States)

    Jiang, Lei; Sun, You-Fang; Zhang, Yu-Yang; Zhou, Guo-Wei; Li, Xiu-Bao; McCook, Laurence J.; Lian, Jian-Sheng; Lei, Xin-Ming; Liu, Sheng; Cai, Lin; Qian, Pei-Yuan; Huang, Hui

    2017-12-01

    Diurnal fluctuations in seawater temperature are ubiquitous on tropical reef flats. However, the effects of such dynamic temperature variations on the early stages of corals are poorly understood. In this study, we investigated the responses of larvae and new recruits of Pocillopora damicornis to two constant temperature treatments (29 and 31 °C) and two diurnally fluctuating treatments (28-31 and 30-33 °C with daily means of 29 and 31 °C, respectively) simulating the 3 °C diel oscillations at 3 m depth on the Luhuitou fringing reef (Sanya, China). Results showed that the thermal stress on settlement at 31 °C was almost negated by the fluctuating treatment. Further, neither elevated temperature nor temperature fluctuations caused bleaching responses in recruits, while the maximum excitation pressure over photosystem II (PSII) was reduced under fluctuating temperatures. Although early growth and development were highly stimulated at 31 °C, oscillations of 3 °C had little effects on budding and lateral growth at either mean temperature. Nevertheless, daytime encounters with the maximum temperature of 33 °C in fluctuating 31 °C elicited a notable reduction in calcification compared to constant 31 °C. These results underscore the complexity of the effects caused by diel temperature fluctuations on early stages of corals and suggest that ecologically relevant temperature variability could buffer warming stress on larval settlement and dampen the positive effects of increased temperatures on coral growth.

  11. Diurnal Dynamics of Wheat Evapotranspiration Derived from Ground-Based Thermal Imagery

    Directory of Open Access Journals (Sweden)

    Hella Ellen Ahrends

    2014-10-01

    Full Text Available The latent heat flux, one of the key components of the surface energy balance, can be inferred from remotely sensed thermal infrared data. However, discrepancies between modeled and observed evapotranspiration are large. Thermal cameras might provide a suitable tool for model evaluation under variable atmospheric conditions. Here, we evaluate the results from the Penman-Monteith, surface energy balance and Bowen ratio approaches, which estimate the diurnal course of latent heat fluxes at a ripe winter wheat stand using measured and modeled temperatures. Under overcast conditions, the models perform similarly, and radiometric image temperatures are linearly correlated with the inverted aerodynamic temperature. During clear sky conditions, the temperature of the wheat ear layer could be used to predict daytime turbulent fluxes (root mean squared error and mean absolute error: 20–35 W∙m−2, r2: 0.76–0.88, whereas spatially-averaged temperatures caused underestimation of pre-noon and overestimation of afternoon fluxes. Errors are dependent on the models’ ability to simulate diurnal hysteresis effects and are largest during intermittent clouds, due to the discrepancy between the timing of image capture and the time needed for the leaf-air-temperature gradient to adapt to changes in solar radiation. During such periods, we suggest using modeled surface temperatures for temporal upscaling and the validation of image data.

  12. Diurnal patterns of productivity of arbuscular mycorrhizal fungi revealed with the Soil Ecosystem Observatory.

    Science.gov (United States)

    Hernandez, Rebecca R; Allen, Michael F

    2013-10-01

    Arbuscular mycorrhizal (AM) fungi are the most abundant plant symbiont and a major pathway of carbon sequestration in soils. However, their basic biology, including their activity throughout a 24-h day : night cycle, remains unknown. We employed the in situ Soil Ecosystem Observatory to quantify the rates of diurnal growth, dieback and net productivity of extra-radical AM fungi. AM fungal hyphae showed significantly different rates of growth and dieback over a period of 24 h and paralleled the circadian-driven photosynthetic oscillations observed in plants. The greatest rates (and incidences) of growth and dieback occurred between noon and 18:00 h. Growth and dieback events often occurred simultaneously and were tightly coupled with soil temperature and moisture, suggesting a rapid acclimation of the external phase of AM fungi to the immediate environment. Changes in the environmental conditions and variability of the mycorrhizosphere may alter the diurnal patterns of productivity of AM fungi, thereby modifying soil carbon sequestration, nutrient cycling and host plant success. © 2013 The Authors. New Phytologist © 2013 New Phytologist Trust.

  13. Lack of diurnal effects on periodic exercise during prolonged cold water immersion.

    Science.gov (United States)

    Doubt, T J; Smith, D J

    1990-03-01

    Diurnal effects on periodic exercise were examined in 8 male divers wearing passive thermal protection during whole body immersions in 5 degrees C water for periods of up to 6 h. Studies were done during the course of 5-day air saturation dives at a depth of 1.61 ATA, with immersions beginning at 1000 h (AM) and 2200 h (PM). During each hour of immersion, leg exercise was done for 3 min each at workloads of 50, 70, and 90 W. Heart rate (HR) at each workload increased uniformly with immersion time, without a change in slope of HR vs. workload. No AM or PM differences occurred. AM resting VO2 increased linearly, and to the same extent as PM, with exposure time. VO2 at 50 W also increased at the same rate as resting values. VO2 at 70 and 90 W were similar for AM and PM and did not vary significantly during the 6-h immersions. Temporal increases in exercise HR may reflect cardiac compensation of diminished plasma volume. Workloads greater than or equal to 70 W generate enough metabolic heat in this specific condition to meet the thermogenic requirement. Lack of diurnal effects on exercise variables may be due to environmental conditions suppressing circadian rhythms.

  14. Does diurnal variation in cough reflex testing exist in healthy young adults?

    Science.gov (United States)

    Perry, Sarah; Huckabee, Maggie-Lee

    2017-05-01

    The aim of this study was to investigate whether diurnal variation in cough reflex sensitivity exists in healthy young adults when a tidal-breathing method is used. Fifty-three participants (19-37 years) underwent cough reflex testing on two occasions: once in the morning (between 9 am - midday) and once in the afternoon (between 2-5 pm). The order of testing was counter-balanced. Within each assessment, participants inhaled successively higher citric acid concentrations via a facemask, with saline solution randomly interspersed to control for a placebo response. The lowest concentration that elicited a reflexive cough response was recorded. Morning cough thresholds (mean=0.6mol/L) were not different from afternoon cough thresholds (mean=0.6mol/L), p=0.16, T=101, r=-0.14. We found no evidence of diurnal variability in cough reflex testing. There was, however, an order effect irrespective of time of day, confirming that healthy participants are able to volitionally modulate their cough response. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Seasonal, Diurnal, and Solar-Cycle Variations of Electron Density at Two West Africa Equatorial Ionization Anomaly Stations

    Directory of Open Access Journals (Sweden)

    Frédéric Ouattara

    2012-01-01

    Full Text Available We analyse the variability of foF2 at two West Africa equatorial ionization anomaly stations (Ouagadougou and Dakar during three solar cycles (from cycle 20 to cycle 22, that is, from 1966 to 1998 for Ouagadougou and from 1971 to 1997 for Dakar. We examine the effect of the changing levels of solar extreme ultraviolet radiation with sunspot number. The study shows high correlation between foF2 and sunspot number (Rz. The correlation coefficient decreases from cycle 20 to cycle 21 at both stations. From cycle 21 to cycle 22 it decreases at Ouagadougou station and increases at Dakar station. The best correlation coefficient, 0.990, is obtained for Dakar station during solar cycle 22. The seasonal variation displays equinoctial peaks that are asymmetric between March and September. The percentage deviations of monthly average data from one solar cycle to another display variability with respect to solar cycle phase and show solar ultraviolet radiation variability with solar cycle phase. The diurnal variation shows a noon bite out with a predominant late-afternoon peak except during the maximum phase of the solar cycle. The diurnal Ouagadougou station foF2 data do not show a significant difference between the increasing and decreasing cycle phases, while Dakar station data do show it, particularly for cycle 21. The percentage deviations of diurnal variations from solar-minimum conditions show more ionosphere during solar cycle 21 at both stations for all three of the other phases of the solar cycle. There is no significant variability of ionosphere during increasing and decreasing solar cycle phases at Ouagadougou station, but at Dakar station there is a significant variability of ionosphere during these two solar-cycle phases.

  16. On the development of new SPMN diurnal video systems for daylight fireball monitoring

    Science.gov (United States)

    Madiedo, J. M.; Trigo-Rodríguez, J. M.; Castro-Tirado, A. J.

    2008-09-01

    Daylight fireball video monitoring High-sensitivity video devices are commonly used for the study of the activity of meteor streams during the night. These provide useful data for the determination, for instance, of radiant, orbital and photometric parameters ([1] to [7]). With this aim, during 2006 three automated video stations supported by Universidad de Huelva were set up in Andalusia within the framework of the SPanish Meteor Network (SPMN). These are endowed with 8-9 high sensitivity wide-field video cameras that achieve a meteor limiting magnitude of about +3. These stations have increased the coverage performed by the low-scan allsky CCD systems operated by the SPMN and, besides, achieve a time accuracy of about 0.01s for determining the appearance of meteor and fireball events. Despite of these nocturnal monitoring efforts, we realised the need of setting up stations for daylight fireball detection. Such effort was also motivated by the appearance of the two recent meteorite-dropping events of Villalbeto de la Peña [8,9] and Puerto Lápice [10]. Although the Villalbeto de la Peña event was casually videotaped, and photographed, no direct pictures or videos were obtained for the Puerto Lápice event. Consequently, in order to perform a continuous recording of daylight fireball events, we setup new automated systems based on CCD video cameras. However, the development of these video stations implies several issues with respect to nocturnal systems that must be properly solved in order to get an optimal operation. The first of these video stations, also supported by University of Huelva, has been setup in Sevilla (Andalusia) during May 2007. But, of course, fireball association is unequivocal only in those cases when two or more stations recorded the fireball, and when consequently the geocentric radiant is accurately determined. With this aim, a second diurnal video station is being setup in Andalusia in the facilities of Centro Internacional de Estudios y

  17. Hierarchical Matching and Regression with Application to Photometric Redshift Estimation

    Science.gov (United States)

    Murtagh, Fionn

    2017-06-01

    This work emphasizes that heterogeneity, diversity, discontinuity, and discreteness in data is to be exploited in classification and regression problems. A global a priori model may not be desirable. For data analytics in cosmology, this is motivated by the variety of cosmological objects such as elliptical, spiral, active, and merging galaxies at a wide range of redshifts. Our aim is matching and similarity-based analytics that takes account of discrete relationships in the data. The information structure of the data is represented by a hierarchy or tree where the branch structure, rather than just the proximity, is important. The representation is related to p-adic number theory. The clustering or binning of the data values, related to the precision of the measurements, has a central role in this methodology. If used for regression, our approach is a method of cluster-wise regression, generalizing nearest neighbour regression. Both to exemplify this analytics approach, and to demonstrate computational benefits, we address the well-known photometric redshift or `photo-z' problem, seeking to match Sloan Digital Sky Survey (SDSS) spectroscopic and photometric redshifts.

  18. Photometric Calibration of the Gemini South Adaptive Optics Imager

    Science.gov (United States)

    Stevenson, Sarah Anne; Rodrigo Carrasco Damele, Eleazar; Thomas-Osip, Joanna

    2017-01-01

    The Gemini South Adaptive Optics Imager (GSAOI) is an instrument available on the Gemini South telescope at Cerro Pachon, Chile, utilizing the Gemini Multi-Conjugate Adaptive Optics System (GeMS). In order to allow users to easily perform photometry with this instrument and to monitor any changes in the instrument in the future, we seek to set up a process for performing photometric calibration with standard star observations taken across the time of the instrument’s operation. We construct a Python-based pipeline that includes IRAF wrappers for reduction and combines the AstroPy photutils package and original Python scripts with the IRAF apphot and photcal packages to carry out photometry and linear regression fitting. Using the pipeline, we examine standard star observations made with GSAOI on 68 nights between 2013 and 2015 in order to determine the nightly photometric zero points in the J, H, Kshort, and K bands. This work is based on observations obtained at the Gemini Observatory, processed using the Gemini IRAF and gemini_python packages, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the National Research Council (Canada), CONICYT (Chile), Ministerio de Ciencia, Tecnología e Innovación Productiva (Argentina), and Ministério da Ciência, Tecnologia e Inovação (Brazil).

  19. Improving Photometric Calibration of Meteor Video Camera Systems

    Science.gov (United States)

    Ehlert, Steven; Kingery, Aaron; Suggs, Robert

    2017-01-01

    We present the results of new calibration tests performed by the NASA Meteoroid Environment Office (MEO) designed to help quantify and minimize systematic uncertainties in meteor photometry from video camera observations. These systematic uncertainties can be categorized by two main sources: an imperfect understanding of the linearity correction for the MEO's Watec 902H2 Ultimate video cameras and uncertainties in meteor magnitudes arising from transformations between the Watec camera's Sony EX-View HAD bandpass and the bandpasses used to determine reference star magnitudes. To address the first point, we have measured the linearity response of the MEO's standard meteor video cameras using two independent laboratory tests on eight cameras. Our empirically determined linearity correction is critical for performing accurate photometry at low camera intensity levels. With regards to the second point, we have calculated synthetic magnitudes in the EX bandpass for reference stars. These synthetic magnitudes enable direct calculations of the meteor's photometric flux within the camera bandpass without requiring any assumptions of its spectral energy distribution. Systematic uncertainties in the synthetic magnitudes of individual reference stars are estimated at approx. 0.20 mag, and are limited by the available spectral information in the reference catalogs. These two improvements allow for zero-points accurate to 0.05 - 0.10 mag in both filtered and unfiltered camera observations with no evidence for lingering systematics. These improvements are essential to accurately measuring photometric masses of individual meteors and source mass indexes.

  20. Astrometric and photometric study of the open cluster NGC 2323

    Directory of Open Access Journals (Sweden)

    Amin M.Y.

    2017-01-01

    Full Text Available We present a study of the open cluster NGC 2323 using astrometric and photometric data. In our study we used two methods that are able to separate open cluster’s stars from those that belong to the stellar background. Our results of calculations by these two methods indicate that: 1 according to the membership probability, NGC 2323 should contain 497 stars, 2 the cluster center should be at 07h 02m 48.s02 and -08° 20' 17''74,3 the limiting radius of NGC 2323 is 2.31 ± 0.04 pc, the surface number density at this radius is 98.16 stars pc −2, 4 the magnitude function has a maximum at about mv = 14 mag, 5 the total mass of NGC 2323 is estimated dynamically by using astrometric data to be 890 M_, and statistically by using photometric data to be 900 M_, and 6 the distance and age of the cluster are found to be equal to 900 ± 100 pc, and 140 ± 20 Myr, respectively. Finally the dynamical evolution parameter τ of the cluster is about 436.2.

  1. A Photometric Machine-Learning Method to Infer Stellar Metallicity

    Science.gov (United States)

    Miller, Adam A.

    2015-01-01

    Following its formation, a star's metal content is one of the few factors that can significantly alter its evolution. Measurements of stellar metallicity ([Fe/H]) typically require a spectrum, but spectroscopic surveys are limited to a few x 10(exp 6) targets; photometric surveys, on the other hand, have detected > 10(exp 9) stars. I present a new machine-learning method to predict [Fe/H] from photometric colors measured by the Sloan Digital Sky Survey (SDSS). The training set consists of approx. 120,000 stars with SDSS photometry and reliable [Fe/H] measurements from the SEGUE Stellar Parameters Pipeline (SSPP). For bright stars (g' < or = 18 mag), with 4500 K < or = Teff < or = 7000 K, corresponding to those with the most reliable SSPP estimates, I find that the model predicts [Fe/H] values with a root-mean-squared-error (RMSE) of approx.0.27 dex. The RMSE from this machine-learning method is similar to the scatter in [Fe/H] measurements from low-resolution spectra..

  2. A PHOTOMETRIC METALLICITY ESTIMATE OF THE VIRGO STELLAR OVERDENSITY

    International Nuclear Information System (INIS)

    An, Deokkeun; Johnson, Jennifer A.; Pinsonneault, Marc H.; Terndrup, Donald M.; Masseron, Thomas; Beers, Timothy C.; Lee, Young Sun; Delahaye, Franck; Yanny, Brian

    2009-01-01

    We determine photometric metal abundance estimates for individual main-sequence stars in the Virgo Overdensity (VOD), which covers almost 1000 deg 2 on the sky, based on a calibration of the metallicity sensitivity of stellar isochrones in the gri filter passbands using field stars with well-determined spectroscopic metal abundances. Despite the low precision of the method for individual stars, we derive [Fe/H] = -2.0 ± 0.1(internal) ± 0.5(systematic) for the metal abundance of the VOD from photometric measurements of 0.7 million stars in the northern Galactic hemisphere with heliocentric distances from ∼10 kpc to ∼20 kpc. The metallicity of the VOD is indistinguishable, within Δ[Fe/H] ≤ 0.2, from that of field halo stars covering the same distance range. This initial application suggests that the Sloan Digital Sky Survey gri passbands can be used to probe the properties of main-sequence stars beyond ∼10 kpc, complementing studies of nearby stars from more metallicity-sensitive color indices that involve the u passband.

  3. Measuring Cosmological Parameters with Photometrically Classified Pan-STARRS Supernovae

    Science.gov (United States)

    Jones, David; Scolnic, Daniel; Riess, Adam; Rest, Armin; Kirshner, Robert; Berger, Edo; Kessler, Rick; Pan, Yen-Chen; Foley, Ryan; Chornock, Ryan; Ortega, Carolyn; Challis, Peter; Burgett, William; Chambers, Kenneth; Draper, Peter; Flewelling, Heather; Huber, Mark; Kaiser, Nick; Kudritzki, Rolf; Metcalfe, Nigel; Tonry, John; Wainscoat, Richard J.; Waters, Chris; Gall, E. E. E.; Kotak, Rubina; McCrum, Matt; Smartt, Stephen; Smith, Ken

    2018-01-01

    We use nearly 1,200 supernovae (SNe) from Pan-STARRS and ~200 low-z (z energy equation of state parameter w to be -0.986±0.058 (stat+sys). If we allow w to evolve with redshift as w(a) = w0 + wa(1-a), we find w0 = -0.923±0.148 and wa = -0.404±0.797. These results are consistent with measurements of cosmological parameters from the JLA and from a new analysis of 1049 spectroscopically confirmed SNe Ia (Scolnic et al. 2017). We try four different photometric classification priors for Pan-STARRS SNe and two alternate ways of modeling the CC SN contamination, finding that none of these variants gives a w that differs by more than 1% from the baseline measurement. The systematic uncertainty on w due to marginalizing over the CC SN contamination, σwCC = 0.019, is approximately equal to the photometric calibration uncertainty and is lower than the systematic uncertainty in the SN\\,Ia dispersion model (σwdisp = 0.024). Our data provide one of the best current constraints on w, demonstrating that samples with ~5% CC SN contamination can give competitive cosmological constraints when the contaminating distribution is marginalized over in a Bayesian framework.

  4. A photometric function of planetary surfaces for gourmets

    Science.gov (United States)

    Shkuratov, Yuriy; Korokhin, Viktor; Shevchenko, Vasilij; Mikhalchenko, Olga; Belskaya, Irina; Kaydash, Vadym; Videen, Gorden; Zubko, Evgenij; Velikodsky, Yuriy

    2018-03-01

    A new photometric model with small number of parameters is presented. The model is based on an assumption that there exist such surfaces for which spatial brightness variations caused by small topography undulations can be reproduced exactly by corresponding spatial variations of albedo. This indistinguishability results in a differential equation suggesting a new photometric function that generalizes, in particular, the Akimov disk-function. Our model provides excellent fits in a wide phase-angle range for integral observations of asteroids of different albedos. We also carried out fitting to integral observations of the Moon and Mercury, confirming difficulties in describing Mercury's phase function at large phase angles, which were also found for the Hapke model. Comparisons of global latitude and longitude trends with our model calculations have shown good coincidence for the Moon. To retrieve the lunar trends, we use the phase-ratio technique, applying it to our telescope observations. Mapping the model parameters using LROC WAC data were carried out for a region comprising the Reiner Gamma formation. This mapping allows us to calculate phase-ratio images of the region, showing at large phase angles systematically steeper phase curves of young craters and smaller steepness for the very Reiner Gamma formation.

  5. AMICO: optimized detection of galaxy clusters in photometric surveys

    Science.gov (United States)

    Bellagamba, Fabio; Roncarelli, Mauro; Maturi, Matteo; Moscardini, Lauro

    2018-02-01

    We present Adaptive Matched Identifier of Clustered Objects (AMICO), a new algorithm for the detection of galaxy clusters in photometric surveys. AMICO is based on the Optimal Filtering technique, which allows to maximize the signal-to-noise ratio (S/N) of the clusters. In this work, we focus on the new iterative approach to the extraction of cluster candidates from the map produced by the filter. In particular, we provide a definition of membership probability for the galaxies close to any cluster candidate, which allows us to remove its imprint from the map, allowing the detection of smaller structures. As demonstrated in our tests, this method allows the deblending of close-by and aligned structures in more than 50 per cent of the cases for objects at radial distance equal to 0.5 × R200 or redshift distance equal to 2 × σz, being σz the typical uncertainty of photometric redshifts. Running AMICO on mocks derived from N-body simulations and semi-analytical modelling of the galaxy evolution, we obtain a consistent mass-amplitude relation through the redshift range of 0.3 slope of ∼0.55 and a logarithmic scatter of ∼0.14. The fraction of false detections is steeply decreasing with S/N and negligible at S/N > 5.

  6. USING COLORS TO IMPROVE PHOTOMETRIC METALLICITY ESTIMATES FOR GALAXIES

    International Nuclear Information System (INIS)

    Sanders, N. E.; Soderberg, A. M.; Levesque, E. M.

    2013-01-01

    There is a well known correlation between the mass and metallicity of star-forming galaxies. Because mass is correlated with luminosity, this relation is often exploited, when spectroscopy is not available, to estimate galaxy metallicities based on single band photometry. However, we show that galaxy color is typically more effective than luminosity as a predictor of metallicity. This is a consequence of the correlation between color and the galaxy mass-to-light ratio and the recently discovered correlation between star formation rate (SFR) and residuals from the mass-metallicity relation. Using Sloan Digital Sky Survey spectroscopy of ∼180, 000 nearby galaxies, we derive 'LZC relations', empirical relations between metallicity (in seven common strong line diagnostics), luminosity, and color (in 10 filter pairs and four methods of photometry). We show that these relations allow photometric metallicity estimates, based on luminosity and a single optical color, that are ∼50% more precise than those made based on luminosity alone; galaxy metallicity can be estimated to within ∼0.05-0.1 dex of the spectroscopically derived value depending on the diagnostic used. Including color information in photometric metallicity estimates also reduces systematic biases for populations skewed toward high or low SFR environments, as we illustrate using the host galaxy of the supernova SN 2010ay. This new tool will lend more statistical power to studies of galaxy populations, such as supernova and gamma-ray burst host environments, in ongoing and future wide-field imaging surveys

  7. Photometric Metallicities of the Small and Large Magellanic Clouds

    Science.gov (United States)

    Miller, Amy Elizabeth

    2018-06-01

    In the field of astronomy, the study of galaxies is vitally important to understanding the structure and evolution of the universe. Within the study of galaxies, of particular interest are the Small and Large Magellanic Clouds (SMC and LMC, respectively), two of the Milky Way’s closest and most massive satellite galaxies. Their close proximity make them ideal candidates for understanding astrophysical processes such as galaxy interactions. In order to fully understand the Magellanic Clouds, it is imperative that the metallicity of the clouds be mapped in detail. In order to accomplish this task, I will use data from the Survey of Magellanic Stellar History (SMASH) which is a deep, multi-band (ugriz) photometric survey of the Magellanic Clouds that contains approximately 400 million objects in 197 fully-calibrated fields. SMASH is an extensive and deep photometric data set that enables the full-scale study of the galactic structure in the Clouds. The SMASH u-band is sensitive to metallicity for main-sequence turn-off stars which we calibrate using SDSS spectroscopy in overlapping regions (mainly standard star fields). The final steps will be to make metallicity maps of the main bodies and peripheries of the LMC and SMC. Ultimately, these metallicity maps will help us trace out population gradients in the Clouds and uncover the origin of their very extended stellar peripheries.

  8. Photometric metallicity map of the Small Magellanic Cloud

    Science.gov (United States)

    Choudhury, S.; Subramaniam, A.; Cole, A. A.; Sohn, Y.-J.

    2018-04-01

    We have created an estimated metallicity map of the Small Magellanic Cloud (SMC) using the Magellanic Cloud Photometric Survey (MCPS) and Optical Gravitational Lensing Experiment (OGLE III) photometric data. This is a first of its kind map of metallicity up to a radius of ˜2.5°. We identify the Red Giant Branch (RGB) in the V, (V - I) colour-magnitude diagrams of small sub-regions of varying sizes in both data sets. We use the slope of the RGB as an indicator of the average metallicity of a sub-region and calibrate the RGB slope to metallicity using available spectroscopic data for selected sub-regions. The average metallicity of the SMC is found to be [Fe/H] = -0.94 dex (σ[Fe/H] = 0.09) from OGLE III and [Fe/H] = -0.95 dex (σ[Fe/H] = 0.08) from MCPS. We confirm a shallow but significant metallicity gradient within the inner SMC up to a radius of 2.5° (-0.045 ± 0.004 to -0.067 ± 0.006 dex deg-1).

  9. Model independent result on possible diurnal effect in DAMA/LIBRA-phase1

    Energy Technology Data Exchange (ETDEWEB)

    Bernabei, R.; D' Angelo, S.; Di Marco, A. [Universita di Roma ' ' Tor Vergata' ' , Dipt. di Fisica, Rome (Italy); INFN, Sezione Roma ' ' Tor Vergata' ' , Rome (Italy); Belli, P. [INFN, Sezione Roma ' ' Tor Vergata' ' , Rome (Italy); Cappella, F.; D' Angelo, A.; Prosperi, D. [Universita di Roma ' ' La Sapienza' ' , Dipt. di Fisica, Rome (Italy); INFN, Sezione Roma, Rome (Italy); Caracciolo, V.; Castellano, S.; Cerulli, R. [INFN, Laboratori Nazionali del Gran Sasso, Assergi (Italy); Dai, C.J.; He, H.L.; Kuang, H.H.; Ma, X.H.; Sheng, X.D.; Wang, R.G. [Chinese Academy of Sciences, Institute of High Energy Physics, Beijing (China); Incicchitti, A. [INFN, Sezione Roma, Rome (Italy); Montecchia, F. [INFN, Sezione Roma ' ' Tor Vergata' ' , Rome (Italy); Universita di Roma ' ' Tor Vergata' ' , Dipt. di Ingegneria Civile e Ingegneria Informatica, Rome (Italy); Ye, Z.P. [Chinese Academy of Sciences, Institute of High Energy Physics, Beijing (China); University of Jing Gangshan, Jiangxi (China)

    2014-03-15

    The results obtained in the search for possible diurnal effect in the single-hit low energy data collected by DAMA/LIBRA-phase1 (total exposure 1.04 ton x year) deep underground at the Gran Sasso National Laboratory (LNGS) of the INFN are presented. At the present level of sensitivity the presence of any significant diurnal variation and of diurnal time structures in the data can be excluded for both the cases of solar and sidereal time. In particular, the diurnal modulation amplitude expected, because of the Earth diurnal motion, on the basis of the DAMA dark matter annual modulation results is below the present sensitivity. (orig.)

  10. Model independent result on possible diurnal effect in DAMA/LIBRA-phase1

    International Nuclear Information System (INIS)

    Bernabei, R.; D'Angelo, S.; Di Marco, A.; Belli, P.; Cappella, F.; D'Angelo, A.; Prosperi, D.; Caracciolo, V.; Castellano, S.; Cerulli, R.; Dai, C.J.; He, H.L.; Kuang, H.H.; Ma, X.H.; Sheng, X.D.; Wang, R.G.; Incicchitti, A.; Montecchia, F.; Ye, Z.P.

    2014-01-01

    The results obtained in the search for possible diurnal effect in the single-hit low energy data collected by DAMA/LIBRA-phase1 (total exposure 1.04 ton x year) deep underground at the Gran Sasso National Laboratory (LNGS) of the INFN are presented. At the present level of sensitivity the presence of any significant diurnal variation and of diurnal time structures in the data can be excluded for both the cases of solar and sidereal time. In particular, the diurnal modulation amplitude expected, because of the Earth diurnal motion, on the basis of the DAMA dark matter annual modulation results is below the present sensitivity. (orig.)

  11. Multiple origin of diurnality in geckos: evidence from eye lens crystallins

    Science.gov (United States)

    Röll, Beate

    2001-05-01

    The large lizard family Gekkonidae comprises about 90 genera (1000 species). While most geckos are nocturnal, the members of about 15 genera are diurnal. All of these species are 'tertiarily' diurnal, i.e. they are descended from 'secondarily' nocturnal ancestors. They have adapted to a diurnal lifestyle in quite different ways, as can be deduced by the crystallin proteins in their lenses. Evaluation of the heterogeneous lens crystallin compositions of diurnal geckos reveals that there are at least three lineages that regained diurnality independently.

  12. Diurnal variation in the performance of rapid response systems: the role of critical care services-a review article.

    Science.gov (United States)

    Sundararajan, Krishnaswamy; Flabouris, Arthas; Thompson, Campbell

    2016-01-01

    The type of medical review before an adverse event influences patient outcome. Delays in the up-transfer of patients requiring intensive care are associated with higher mortality rates. Timely detection and response to a deteriorating patient constitute an important function of the rapid response system (RRS). The activation of the RRS for at-risk patients constitutes the system's afferent limb. Afferent limb failure (ALF), an important performance measure of rapid response systems, constitutes a failure to activate a rapid response team (RRT) despite criteria for calling an RRT. There are diurnal variations in hospital staffing levels, the performance of rapid response systems and patient outcomes. Fewer ward-based nursing staff at night may contribute to ALF. The diurnal variability in RRS activity is greater in unmonitored units than it is in monitored units for events that should result in a call for an RRT. RRT events include a significant abnormality in either the pulse rate, blood pressure, conscious state or respiratory rate. There is also diurnal variation in RRT summoning rates, with most activations occurring during the day. The reasons for this variation are mostly speculative, but the failure of the afferent limb of RRT activation, particularly at night, may be a factor. The term "circadian variation/rhythm" applies to physiological variations over a 24-h cycle. In contrast, diurnal variation applies more accurately to extrinsic systems. Circadian rhythm has been demonstrated in a multitude of bodily functions and disease states. For example, there is an association between disrupted circadian rhythms and abnormal vital parameters such as anomalous blood pressure, irregular pulse rate, aberrant endothelial function, myocardial infarction, stroke, sleep-disordered breathing and its long-term consequences of hypertension, heart failure and cognitive impairment. Therefore, diurnal variation in patient outcomes may be extrinsic, and more easily modifiable

  13. Effect of realistic and filtered stellar photometric noise on the detection of moons using photometric transit timing

    Directory of Open Access Journals (Sweden)

    Lewis K.

    2011-02-01

    Full Text Available The photometric transit timing technique was proposed by Szabó et al. (2006 as a method for discovering moons of transiting extrasolar planets. In the preliminary analysis of this technique, it was assumed that the noise in the transit lightcurve was well described by uncorrelated white noise. However, this assumption is not necessarily realistic. To determine the effect of using more realistic lightcurves, transit timing uncertainties are calculated for the case of white noise, measured solar photometric noise and measured solar photometric noise that has been filtered. It is found that for light curves contaminated with realistic photometric noise, the transit timing uncertainties are dramatically increased (and thus moon detection reduced. In addition, we find that while filtering reduced this problem, it did not negate it.

  14. Results of a Long-Term Spectral and Photometric Monitoring of the Herbig Ae Star HD 179218

    Science.gov (United States)

    Kozlova, O. V.; Alekseev, I. Yu.

    2017-06-01

    We present the results of the long-term spectroscopic and photometric monitoring of the Herbig Ae star HD 179218. The high-resolution spectra (R = 20000) were made on the 2.6-m telescope at the Crimean Astrophysical Observatory (CrAO) in the regions of Hα emission line. The photometric observations were obtained on 1.25-m telescope AZT-11 (CrAO) equipped with the UBVRI electrophotometer-polarimeter. Our results showed that Hα emission parameters demonstrate the long- term variability on the time scale about 4000 days. The same variability is observed in the change of the stellar brightness in V-band. The unusual behavior the V-I color index depending on the stellar brightness in the V-band can be concluded that around the star there is an additional source of IR-radiation. We believe that the obtained results can be explained by the presence in the vicinity of HD 179218 a low-mass component.

  15. Photometric light curves for seven rapidly-rotating K dwarfs in the Pleiades and Alpha Persei clusters

    Science.gov (United States)

    Stauffer, John R.; Schild, Rudolph A.; Baliunas, Sallie L.; Africano, John L.

    1987-01-01

    Light curves and period estimates were obtained for several Pleiades and Alpha Persei cluster K dwarfs which were identified as rapid rotators in earlier spectroscopic studies. A few of the stars have previously-published light curves, making it possible to study the long-term variability of the light-curve shapes. The general cause of the photometric variability observed for these stars is an asymmetric distribution of photospheric inhomogeneities (starspots). The presence of these inhomogeneities combined with the rotation of the star lead to the light curves observed. The photometric periods derived are thus identified with the rotation period of the star, making it possible to estimate equatorial rotational velocities for these K dwarfs. These data are of particular importance because the clusters are sufficiently young that stars of this mass should have just arrived on the main sequence. These data could be used to estimate the temperatures and sizes of the spot groups necessary to produce the observed light curves for these stars.

  16. Modeling and Simulation of Optimal Resource Management during the Diurnal Cycle in Emiliania huxleyi by Genome-Scale Reconstruction and an Extended Flux Balance Analysis Approach.

    Science.gov (United States)

    Knies, David; Wittmüß, Philipp; Appel, Sebastian; Sawodny, Oliver; Ederer, Michael; Feuer, Ronny

    2015-10-28

    The coccolithophorid unicellular alga Emiliania huxleyi is known to form large blooms, which have a strong effect on the marine carbon cycle. As a photosynthetic organism, it is subjected to a circadian rhythm due to the changing light conditions throughout the day. For a better understanding of the metabolic processes under these periodically-changing environmental conditions, a genome-scale model based on a genome reconstruction of the E. huxleyi strain CCMP 1516 was created. It comprises 410 reactions and 363 metabolites. Biomass composition is variable based on the differentiation into functional biomass components and storage metabolites. The model is analyzed with a flux balance analysis approach called diurnal flux balance analysis (diuFBA) that was designed for organisms with a circadian rhythm. It allows storage metabolites to accumulate or be consumed over the diurnal cycle, while keeping the structure of a classical FBA problem. A feature of this approach is that the production and consumption of storage metabolites is not defined externally via the biomass composition, but the result of optimal resource management adapted to the diurnally-changing environmental conditions. The model in combination with this approach is able to simulate the variable biomass composition during the diurnal cycle in proximity to literature data.

  17. Modeling and Simulation of Optimal Resource Management during the Diurnal Cycle in Emiliania huxleyi by Genome-Scale Reconstruction and an Extended Flux Balance Analysis Approach

    Directory of Open Access Journals (Sweden)

    David Knies

    2015-10-01

    Full Text Available The coccolithophorid unicellular alga Emiliania huxleyi is known to form large blooms, which have a strong effect on the marine carbon cycle. As a photosynthetic organism, it is subjected to a circadian rhythm due to the changing light conditions throughout the day. For a better understanding of the metabolic processes under these periodically-changing environmental conditions, a genome-scale model based on a genome reconstruction of the E. huxleyi strain CCMP 1516 was created. It comprises 410 reactions and 363 metabolites. Biomass composition is variable based on the differentiation into functional biomass components and storage metabolites. The model is analyzed with a flux balance analysis approach called diurnal flux balance analysis (diuFBA that was designed for organisms with a circadian rhythm. It allows storage metabolites to accumulate or be consumed over the diurnal cycle, while keeping the structure of a classical FBA problem. A feature of this approach is that the production and consumption of storage metabolites is not defined externally via the biomass composition, but the result of optimal resource management adapted to the diurnally-changing environmental conditions. The model in combination with this approach is able to simulate the variable biomass composition during the diurnal cycle in proximity to literature data.

  18. A non-convex variational approach to photometric stereo under inaccurate lighting

    DEFF Research Database (Denmark)

    Quéau, Yvain; Wu, Tao; Lauze, Francois Bernard

    2017-01-01

    This paper tackles the photometric stereo problem in the presence of inaccurate lighting, obtained either by calibration or by an uncalibrated photometric stereo method. Based on a precise modeling of noise and outliers, a robust variational approach is introduced. It explicitly accounts for self...

  19. Photometric data from some photographs of Mars obtained with the Automatic Interplanetary Station 'Mars 3'

    International Nuclear Information System (INIS)

    Botvinova, V.V.; Bugaenko, O.I.; Koval, I.K.; Narajeva, M.K.; Selivanov, A.S.

    1974-01-01

    The results of detailed photometric treatment of Mars photographs obtained with the Automatic Interplanetary Station 'Mars 3' in three wavelengths are given. Photometric maps of the Martian surface have been constructed; a thin layer observed near the limb has been investigated. (Auth.)

  20. Dissecting Photometric Redshift for Active Galactic Nucleus Using XMM- and Chandra-COSMOS Samples

    NARCIS (Netherlands)

    Salvato, M.; Ilbert, O.; Hasinger, G.; Rau, A.; Civano, F.; Zamorani, G.; Brusa, M.; Elvis, M.; Vignali, C.; Aussel, H.; Comastri, A.; Fiore, F.; Le Floc'h, E.; Mainieri, V.; Bardelli, S.; Bolzonella, M.; Bongiorno, A.; Capak, P.; Caputi, K.; Cappelluti, N.; Carollo, C. M.; Contini, T.; Garilli, B.; Iovino, A.; Fotopoulou, S.; Fruscione, A.; Gilli, R.; Halliday, C.; Kneib, J. -P.; Kakazu, Y.; Kartaltepe, J. S.; Koekemoer, A. M.; Kovac, K.; Ideue, Y.; Ikeda, H.; Impey, C. D.; Le Fevre, O.; Lamareille, F.; Lanzuisi, G.; Le Borgne, J. -F.; Le Brun, V.; Lilly, S.; Maier, C.; Manohar, S.; Masters, D.; McCracken, H.; Messias, H.; Mignoli, M.; Mobasher, B.; Nagao, T.; Pello, R.; Puccetti, S.; Perez-Montero, E.; Renzini, A.; Sargent, M.; Sanders, D. B.; Scodeggio, M.; Scoville, N.; Shopbell, P.; Silvermann, J.; Taniguchi, Y.; Tasca, L.; Tresse, L.; Trump, J. R.; Zucca, E.

    2011-01-01

    In this paper, we release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of the Cosmic Evolution Survey (COSMOS) field. The availability of a large training set of spectroscopic redshifts that extends to faint magnitudes enabled photometric

  1. Methods of photometric analysis of ore-enclosing rocks and ores

    International Nuclear Information System (INIS)

    Danchev, V.I.

    1985-01-01

    A photometric method for investigation of colour of sedimentary rocks being of importance in prospecting for uranium deposits is considered. Attention is paid to sample preparation for analysis, protometry procedure. An example of using the photometric method for studying carbonate uranium-bearing rocks is given

  2. The Diurnal Cycle of the Boundary Layer, Convection, Clouds, and Surface Radiation in a Coastal Monsoon Environment (Darwin Australia)

    Energy Technology Data Exchange (ETDEWEB)

    May, Peter T.; Long, Charles N.; Protat, Alain

    2012-08-01

    The diurnal variation of convection and associated cloud and radiative properties remains a significant issue in global NWP and climate models. This study analyzes observed diurnal variability of convection in a coastal monsoonal environment examining the interaction of convective rain clouds, their associated cloud properties, and the impact on the surface radiation and corresponding boundary layer structure during periods where convection is suppressed or active on the large scale. The analysis uses data from the Tropical Warm Pool International Cloud Experiment (TWP-ICE) as well as routine measurements from the Australian Bureau of Meteorology and the U.S. Department of Energy Atmospheric Radiation Measurement (ARM) program. Both active monsoonal and large-scale suppressed (buildup and break) conditions are examined and demonstrate that the diurnal variation of rainfall is much larger during the break periods and the spatial distribution of rainfall is very different between the monsoon and break regimes. During the active monsoon the total net radiative input to the surface is decreased by more than 3 times the amount than during the break regime - this total radiative cloud forcing is found to be dominated by the shortwave (SW) cloud effects because of the much larger optical thicknesses and persistence of long-lasting anvils and cirrus cloud decks associated with the monsoon regime. These differences in monsoon versus break surface radiative energy contribute to low-level air temperature differences in the boundary layer over the land surfaces.

  3. Generation of diurnal variation for influent data for dynamic simulation.

    Science.gov (United States)

    Langergraber, G; Alex, J; Weissenbacher, N; Woerner, D; Ahnert, M; Frehmann, T; Halft, N; Hobus, I; Plattes, M; Spering, V; Winkler, S

    2008-01-01

    When using dynamic simulation for fine tuning of the design of activated sludge (AS) plants diurnal variations of influent data are required. For this application usually only data from the design process and no measured data are available. In this paper a simple method to generate diurnal variations of wastewater flow and concentrations is described. The aim is to generate realistic influent data in terms of flow, concentrations and TKN/COD ratios and not to predict the influent of the AS plant in detail. The work has been prepared within the framework of HSG-Sim (Hochschulgruppe Simulation, http://www.hsgsim.org), a group of researchers from Germany, Austria, Luxembourg, Poland, the Netherlands and Switzerland. (c) IWA Publishing 2008.

  4. Effects of the Relaxation of Upwelling-Favorable Winds on the Diurnal and Semidiurnal Water Temperature Fluctuations in the Santa Barbara Channel, California

    Science.gov (United States)

    Aristizábal, María. F.; Fewings, Melanie R.; Washburn, Libe

    2017-10-01

    In the Santa Barbara Channel, California, and around the Northern Channel Islands, water temperature fluctuations in the diurnal and semidiurnal frequency bands are intermittent, with amplitudes that vary on time scales of days to weeks. The cause of this intermittency is not well understood. We studied the effects of the barotropic tide, vertical stratification, propagation of coastal-trapped waves, regional wind relaxations, and diurnal-band winds on the intermittency of the temperature fluctuations during 1992-2015. We used temperature data from 43 moorings in 10-200 m water depth and wind data from two buoys and one land station. Subtidal-frequency changes in vertical stratification explain 20-40% of the intermittency in diurnal and semidiurnal temperature fluctuations at time scales of days to weeks. Along the mainland north of Point Conception and at the Northern Channel Islands, the relaxation of upwelling-favorable winds substantially increases vertical stratification, accounting for up to 55% of the subtidal-frequency variability in stratification. As a result of the enhanced stratification, wind relaxations enhance the diurnal and semidiurnal temperature fluctuations at those sites, even though the diurnal-band wind forcing decreases during wind relaxation. A linear model where the background stratification is advected vertically explains a substantial fraction of the temperature fluctuations at most sites. The increase of vertical stratification and subsequent increase in diurnal and semidiurnal temperature fluctuations during wind relaxation is a mechanism that can supply nutrients to the euphotic zone and kelp forests in the Channel in summer when upwelling is weak.

  5. Cognitive control moderates parenting stress effects on children's diurnal cortisol

    OpenAIRE

    Raffington, Laurel; Schmiedek, Florian; Heim, Christine; Shing, Yee Lee

    2018-01-01

    This study investigated associations between parenting stress in parents and self-reported stress in children with children's diurnal cortisol secretion and whether these associations are moderated by known stress-regulating capacities, namely child cognitive control. Salivary cortisol concentrations were assessed from awakening to evening on two weekend days from 53 6-to-7-year-old children. Children completed a cognitive control task and a self-report stress questionnaire with an experiment...

  6. Central melanopsin projections in the diurnal rodent, Arvicanthis niloticus

    Directory of Open Access Journals (Sweden)

    Jennifer Lou Langel

    2015-07-01

    Full Text Available The direct effects of photic stimuli on behavior are very different in diurnal and nocturnal species, as light stimulates an increase in activity in the former and a decrease in the latter. Studies of nocturnal mice have implicated a select population of retinal ganglion cells that are intrinsically photosensitive (ipRGCs in mediation of these acute responses to light. ipRGCs are photosensitive due to the expression of the photopigment melanopsin; these cells use glutamate and pituitary adenylate cyclase-activating polypeptide (PACAP as neurotransmitters. PACAP is useful for the study of central ipRGC projections because, in the retina, it is found exclusively within melanopsin cells. Little is known about the central projections of ipRGCs in diurnal species. Here, we first characterized these cells in the retina of the diurnal Nile grass rat using immunohistochemistry (IHC. The same basic subtypes of melanopsin cells that have been described in other mammals were present, but nearly 25% of them were displaced, primarily in its superior region. PACAP was present in 87.7% of all melanopsin cells, while 97.4% of PACAP cells contained melanopsin. We then investigated central projections of ipRGCs by examining the distribution of immunoreactive PACAP fibers in intact and enucleated animals. This revealed evidence that these cells project to the suprachiasmatic nucleus, lateral geniculate nucleus (LGN, pretectum and superior colliculus. This distribution was confirmed with injections of cholera toxin subunit β coupled with Alexa Fluor 488 in one eye and Alexa Flour 594 in the other, combined with IHC staining of PACAP. These studies also revealed that the ventral and dorsal LGN and the caudal olivary pretectal nucleus receive less innervation from ipRGCs than that reported in nocturnal rodents. Overall, these data suggest that although ipRGCs and their projections are very similar in diurnal and nocturnal rodents, they may not be identical.

  7. Circadian modulation of complex learning in diurnal and nocturnal Aplysia

    OpenAIRE

    Lyons, Lisa C.; Rawashdeh, Oliver; Katzoff, Ayelet; Susswein, Abraham J.; Eskin, Arnold

    2005-01-01

    Understanding modulation of memory, as well as the mechanisms underlying memory formation, has become a key issue in neuroscience research. Previously, we found that the formation of long-term, but not short-term, memory for a nonassociative form of learning, sensitization, was modulated by the circadian clock in the diurnal Aplysia californica. To define the scope of circadian modulation of memory, we examined an associative operant learning paradigm, learning that food is inedible (LFI). Si...

  8. Diurnal bird visiting of Caryocar brasiliense Camb. in Central Brazil

    OpenAIRE

    MELO, C.

    2001-01-01

    Nectar of nocturnal flowers may be used by diurnal species that occasionally accomplish secondary pollination. Thirteen bird species visited Caryocar brasiliense flowers in central Brazil. There is a temporal separation between nectarivores and non-nectarivores species. Nectarivores birds visited flowers late in the morning, while other species appear earlier. C. brasiliense nectar may be an alternative resource to birds visitors during the dry season. O néctar de flores noturnas pode ser ...

  9. Simulation analysis of photometric data for attitude estimation of unresolved space objects

    Science.gov (United States)

    Du, Xiaoping; Gou, Ruixin; Liu, Hao; Hu, Heng; Wang, Yang

    2017-10-01

    The attitude information acquisition of unresolved space objects, such as micro-nano satellites and GEO objects under the way of ground-based optical observations, is a challenge to space surveillance. In this paper, a useful method is proposed to estimate the SO attitude state according to the simulation analysis of photometric data in different attitude states. The object shape model was established and the parameters of the BRDF model were determined, then the space object photometric model was established. Furthermore, the photometric data of space objects in different states are analyzed by simulation and the regular characteristics of the photometric curves are summarized. The simulation results show that the photometric characteristics are useful for attitude inversion in a unique way. Thus, a new idea is provided for space object identification in this paper.

  10. Diurnal Alterations of Refraction, Anterior Segment Biometrics, and Intraocular Pressure in Long-Time Dehydration due to Religious Fasting.

    Science.gov (United States)

    Baser, Gonen; Cengiz, Hakan; Uyar, Murat; Seker Un, Emine

    2016-01-01

    To investigate the effects of dehydration due to fasting on diurnal changes of intraocular pressure, anterior segment biometrics, and refraction. The intraocular pressures, anterior segment biometrics (axial length: AL; Central corneal thickness: CCT; Lens thickness: LT; Anterior chamber depth: ACD), and refractive measurements of 30 eyes of 15 fasting healthy male volunteers were recorded at 8:00 in the morning and 17:00 in the evening in the Ramadan of 2013 and two months later. The results were compared and the statistical analyses were performed using the Rstudio software version 0.98.501. The variables were investigated using visual (histograms, probability plots) and analytical methods (Kolmogorov-Smirnov/Shapiro-Wilk test) to determine whether or not they were normally distributed. The refractive values remained stable in the fasting as well as in the control period (p = 0.384). The axial length measured slightly shorter in the fasting period (p = 0.001). The corneal thickness presented a diurnal variation, in which the cornea measured thinner in the evening. The difference between the fasting and control period was not statistically significant (p = 0.359). The major differences were observed in the anterior chamber depth and IOP. The ACD was shallower in the evening during the fasting period, where it was deeper in the control period. The diurnal IOP difference was greater in the fasting period than the control period. Both were statistically significant (p = 0.001). The LT remained unchanged in both periods. The major difference was shown in the anterior chamber shallowing in the evening hours and IOP. Our study contributes the hypothesis that the posterior segment of the eye is more responsible for the axial length alterations and normovolemia has a more dominant influence on diurnal IOP changes.

  11. Prenatal exposure to diurnal temperature variation and early childhood pneumonia.

    Science.gov (United States)

    Zeng, Ji; Lu, Chan; Deng, Qihong

    2017-04-01

    Childhood pneumonia is one of the leading single causes of mortality and morbidity in children worldwide, but its etiology still remains unclear. We investigate the association between childhood pneumonia and exposure to diurnal temperature variation (DTV) in different timing windows. We conducted a prospective cohort study of 2,598 children aged 3-6 years in Changsha, China. The lifetime prevalence of pneumonia was assessed by a questionnaire administered by the parents. Individual exposure to DTV during both prenatal and postnatal periods was estimated. Logic regression models was used to examine the association between childhood pneumonia and DTV exposure in terms of odds ratios (OR) and 95% confidence interval (CI). Lifetime prevalence of childhood pneumonia in preschool children in Changsha was high up to 38.6%. We found that childhood pneumonia was significantly associated with prenatal DTV exposure, with adjusted OR (95%CI) =1.19 (1.02-1.38), particularly during the second trimester. However, childhood pneumonia not associated with postnatal DTV exposure. Sensitivity analysis indicated that boys are more susceptible to the pneumonia risk of diurnal temperature variation than girls. We further observed that the prevalence of childhood pneumonia was decreased in recent years as DTV shrinked. Early childhood pneumonia was associated with prenatal exposure to the diurnal temperature variation (DTV) during pregnancy, particularly in the second trimester, which suggests fetal origin of childhood pneumonia. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Familial circadian rhythm disorder in the diurnal primate, Macaca mulatta.

    Directory of Open Access Journals (Sweden)

    Irina V Zhdanova

    Full Text Available In view of the inverse temporal relationship of central clock activity to physiological or behavioral outputs in diurnal and nocturnal species, understanding the mechanisms and physiological consequences of circadian disorders in humans would benefit from studies in a diurnal animal model, phylogenetically close to humans. Here we report the discovery of the first intrinsic circadian disorder in a family of diurnal non-human primates, the rhesus monkey. The disorder is characterized by a combination of delayed sleep phase, relative to light-dark cycle, mutual desynchrony of intrinsic rhythms of activity, food intake and cognitive performance, enhanced nighttime feeding or, in the extreme case, intrinsic asynchrony. The phenotype is associated with normal length of intrinsic circadian period and requires an intact central clock, as demonstrated by an SCN lesion. Entrainment to different photoperiods or melatonin administration does not eliminate internal desynchrony, though melatonin can temporarily reinstate intrinsic activity rhythms in the animal with intrinsic asynchrony. Entrainment to restricted feeding is highly effective in animals with intrinsic or SCN lesion-induced asynchrony. The large isolated family of rhesus macaques harboring the disorder provides a powerful new tool for translational research of regulatory circuits underlying circadian disorders and their effective treatment.

  13. Spectral and diurnal variations in clear sky planetary albedo

    Science.gov (United States)

    Briegleb, B.; Ramanathan, V.

    1982-01-01

    Spectral and diurnal variations in the clear sky planetary albedo of the earth are calculated using a radiative transfer model to obtain January and July values for a 5 deg x 5 deg global grid. The model employs observed climatological values of temperatures, humidities, snow and sea-ice cover. The diurnal cycle of clear sky albedo is calculated in the following intervals: 0.2-0.5, 0.5-0.7, and 0.7-4 microns. Observed ozone distribution is specified as a function of latitude and season. The 0.2-0.5 micron spectral albedo is 10-20% higher than the total albedo for all latitudes because of Rayleigh scattering; the 0.5-0.7 micron albedo differs from the total albedo by 1-2% for most latitudes, while the 0.7-4 micron albedo is 5-10% lower than the total because of strong atmospheric absorption. Planetary albedo decreases from morning to local noon, with diurnal variations being particularly strong over water.

  14. On the Sensitivity of the Diurnal Cycle in the Amazon to Convective Intensity

    Science.gov (United States)

    Itterly, Kyle; Taylor, Patrick

    2015-01-01

    This presentation uses publicly available CERES and radiosonde data to investigate the sensitivity of thetropical convective diurnal cycle to atmosphere state. Averaging surface observations into regimes of convective intensitydefined by satellite shows great promise for physical understandingof convection.• Convective processes in the Amazon are highly variable seasonallyand locally.• Buoyancy/CIN more important JJA– Mesoscale/synoptic features easier to separate– Length/depth of buoyancy layer very important in DJF (EL).• Moisture more important DJF, esp. UTH– Humidity of lower atmosphere significantly impacts LTS, LCL and abilityfor parcels to reach LFC.• Lower level jet strength/direction important• Convective initiation correlated with LTS, LR, LTH, EL• Duration/Phase better correlated with humidity variables• Surface Flux amplitude well correlated with convection

  15. Eclipsing binaries observed with the WIRE satellite I. Discovery and photometric analysis of the new bright A0 IV eclipsing binary psi centauri

    DEFF Research Database (Denmark)

    Bruntt, Hans; Southworth, J.; Penny, A. J.

    2006-01-01

    Stars: fundamental parameters, binaries: close, eclipsing, techniques: photometric Udgivelsesdato: Sep.......Stars: fundamental parameters, binaries: close, eclipsing, techniques: photometric Udgivelsesdato: Sep....

  16. Diurnal patterns and associations among salivary cortisol, DHEA and alpha-amylase in older adults.

    Science.gov (United States)

    Wilcox, Rand R; Granger, Douglas A; Szanton, Sarah; Clark, Florence

    2014-04-22

    Cortisol and dehydroepiandrosterone (DHEA) are considered to be valuable markers of the hypothalamus-pituitary-adrenal (HPA) axis, while salivary alpha-amylase (sAA) reflects the autonomic nervous system. Past studies have found certain diurnal patterns among these biomarkers, with some studies reporting results that differ from others. Also, some past studies have found an association among these three biomarkers while other studies have not. This study investigates these patterns and associations in older adults by taking advantage of modern statistical methods for dealing with non-normality, outliers and curvature. Basic characteristics of the data are reported as well, which are relevant to understanding the nature of any patterns and associations. Boxplots were used to check on the skewness and presence of outliers, including the impact of using simple transformations for dealing with non-normality. Diurnal patterns were investigated using recent advances aimed at comparing medians. When studying associations, the initial step was to check for curvature using a non-parametric regression estimator. Based on the resulting fit, a robust regression estimator was used that is designed to deal with skewed distributions and outliers. Boxplots indicated highly skewed distributions with outliers. Simple transformations (such as taking logs) did not deal with this issue in an effective manner. Consequently, diurnal patterns were investigated using medians and found to be consistent with some previous studies but not others. A positive association between awakening cortisol levels and DHEA was found when DHEA is relatively low; otherwise no association was found. The nature of the association between cortisol and DHEA was found to change during the course of the day. Upon awakening, cortisol was found to have no association with sAA when DHEA levels are relatively low, but otherwise there is a negative association. DHEA was found to have a positive association with s

  17. Seasonal Cycle of the Near-Surface Diurnal Wind Field Over the Bay of La Paz, Mexico

    Science.gov (United States)

    Turrent, Cuauhtémoc; Zaitsev, Oleg

    2014-05-01

    The results of numerical simulations of the troposphere over the Bay of La Paz, calculated for the months of January, April, July and October during the period 2006-2010 with the Weather Research and Forecast (WRF v3.5) regional model, are used to describe the seasonal features of the diurnal cycle of planetary boundary-layer winds. Two distinct near-surface diurnal flows with strong seasonal variability were identified: (1) a nocturnal and matutinal breeze directed from the subtropical Pacific Ocean, over the Baja California peninsula and the Bay of La Paz, into the Gulf of California that is associated with the regional sea-surface temperature difference between those two major water bodies; and (2) a mid to late afternoon onshore sea-breeze related to the peninsula's daily cycle of insolation heating that evolves with counter-clockwise rotation over the Bay of La Paz. The model results reveal the interaction over Baja California of opposing afternoon sea-breeze fronts that originate from the subtropical Pacific Ocean and the Gulf of California, with a convergence line forming over the peaks of the peninsula's topography and the associated presence of a closed vertical circulation cell over the Bay of La Paz and the adjacent Gulf. The collision of the opposing sea-breeze fronts over the narrow peninsula drives convection that is relatively weak due to the reduced heat source and only appears to produce precipitation sporadically. The spatial structure of the sea-breeze fronts over the Bay of La Paz region is complex due to shoreline curvature and nearby topographic features. A comparison of the numerical results with available meteorological near-surface observations indicates that the modelling methodology adequately reproduced the observed features of the seasonal variability of the local planetary boundary-layer diurnal wind cycle and confirms that the low-level atmospheric circulation over the Bay of La Paz is dominated by kinetic energy in the diurnal band

  18. Photometric Separation of Stellar Properties Using SDSS Filters

    Science.gov (United States)

    Lenz, Dawn D.; Newberg, Jo; Rosner, Robert; Richards, Gordon T.; Stoughton, Chris

    1998-12-01

    Using synthetic photometry of Kurucz model spectra, we explore the colors of stars as a function of temperature, metallicity, and surface gravity with Sloan Digital Sky Survey (SDSS) filters, u'g'r'i'z'. The synthetic colors show qualitative agreement with the few published observations in these filters. We find that the locus of synthetic stars is basically two-dimensional for 4500 advantageous to use more than two colors when determining stellar properties by color. Strategic observations in SDSS filters are required to resolve the source of a ~5% discrepancy between synthetic colors of Gunn-Stryker stars, Kurucz models, and external determinations of the metallicities and surface gravities. The synthetic star colors can be used to investigate the properties of any normal star and to construct analytic expressions for the photometric prediction of stellar properties in special cases.

  19. Photometric determination of phosphorus in zircon concentrate and potassium hexafluorozirconate

    International Nuclear Information System (INIS)

    Polonskaya, I.A.; Fominykh, N.L.

    1978-01-01

    A method for direct photometric phosphorus determination in the materials, containing considerable zirconium amounts is developed. Phosphorus is determined in a form of reduced heteropolyacid with the use of ascorbic acid and potassium antimonyltartrate in sulfuric acid medium. To remove zirconium effect, a graduation diagram is drawn at the background of zirconium, which is bound into a stable fluoride complex in the presence of H 3 BO 3 . Under the above conditions the coloring developes after 30-40 min and remains stable for 24 hrs. A proportional dependence between phosphorus concentration and optical density is observed in the range of 10-160 mg of Zr. The method sensitivity is 5x10 -5 %

  20. Revised photometric elements of the eclipsing binary TW Dra

    International Nuclear Information System (INIS)

    Giuricin, G.; Mardirossian, F.; Predolin, F.

    1980-01-01

    The photoelectric light curves of TW Dra obtained by Baglow (1952) and by Waltser (1978) have been re-analysed by means of Wood's (1972) model in order to obtain accurate photometric elements. Significantly different elements have resulted from the two sets of observations, but more confidence can be given to the elements deduced from Walter's (1978) data. Radii and luminosities have been computed with the aid of Popper's (1978) new values for masses. TW Dra is confirmed to be a typical sd-system, having a distrinctly oversized and overluminous secondary. Interestingly, the primary appears to be slightly more luminous than expected for a Main-Sequences star, in agreement with theoretical predictions for present primaries of mass-exchange binaries systems. (orig.)

  1. Direct photometric determination of fluorides in potassium chloride and iodide

    International Nuclear Information System (INIS)

    Dedkova, V.P.; Savvin, S.B.

    1985-01-01

    An attempt is made to apply the technique of determining fluorides with xylenol orange and sulfochlorophenol S as being the most sensitive in the analysis of of fiber optics. It is known that an increase of the sensitivity of the determination can be achieved on increasing the sample size of the substance to be analyzed, and the length of the absorbing layer. However, a high salt background may have a strong influence on the course of the reaction, and a supplementary of this effect is mad. Potassium chloride and iodide were selected as model compounds. A direct photometric procedure is proposed for determining fluorides in the samples, with a determination limit of 5 x 10 -6 %. Such a low determination limit is achieved by increasing the sample weight to 3 g, by increasing the length of the absorbing layer in the cell to 50 mm, and by using a highly sensitive reaction for determining fluorides with zirconium and xylenol orange

  2. Photometric observations of V470 Cygni (HD 228911)

    International Nuclear Information System (INIS)

    Ebbighausen, E.G.; Lester, D.; Stearns, S.; Straton, P; Sykes, M.

    1975-01-01

    Previous photometric observations of this type B2 spectroscopic binary with a 1.87d period have shown small but not well-defined light variations suggesting that it is an eclipsing binary with a rather small orbital inclination. In the summer of 1974 the authors obtained photoelectrically 2060 individual V observations and 2100 B observations of V470 Cygni at the Pine Mountain Observatory of the University of Oregon. The total light range in both colors is nearly 0.02m and the form of the light curve suggests that this object is an ellipsoidal binary. A new epoch of primary minimum and period are derived. All of the data combined are insufficient to confirm Pearce's suggestion of apsidal motion

  3. Photometric observations of local rocket-atmosphere interactions

    Science.gov (United States)

    Greer, R. G. H.; Murtagh, D. P.; Witt, G.; Stegman, J.

    1983-06-01

    Photometric measurements from rocket flights which recorded a strong foreign luminance in the altitude region between 90 and 130 km are reported. From one Nike-Orion rocket the luminance appeared on both up-leg and down-leg; from a series of Petrel rockets the luminance was apparent only on the down-leg. The data suggest that the luminance may be distributed mainly in the wake region along the rocket trajectory. The luminance is believed to be due to a local interaction between the rocket and the atmosphere although the precise nature of the interaction is unknown. It was measured at wavelengths ranging from 275 nm to 1.61 microns and may be caused by a combination of reactions.

  4. Optical and near-infrared photometric study of NGC 6724

    Science.gov (United States)

    Bendary, Reda; Tadross, Ashraf; Hasan, Priya; Osman, Anas; Essam, Ahmed

    2018-02-01

    BVRI CCD photometry of the poorly studied open cluster NGC 6724 has been carried out down to a limiting magnitude of V∼20 mag. The stars of the cluster have been observed using the Newtonian focus (f/4.84) of the 74-inch telescope at Kottamia Astronomical Observatory in Egypt. Also, the 2MASS - JHK system is used to confirm the results we obtained. The main photometric parameters have been estimated for the present object; the diameter is found to be 6 arcmin, the distance is 1530±60 pc from the Sun and the age is 900±50 Myr. The optical reddening E(B-V)=0.65 {mag}, while the infrared reddening is E(J-H)=0.20 {mag}. The slope of the mass function distribution and the relaxation time estimations indicate that cluster NGC 6724 is dynamically relaxed.

  5. Spectral classification by the near infrared photometric parameters

    International Nuclear Information System (INIS)

    Tignanelli, H.L.; Feinstein, A.

    1985-01-01

    From the analysis of the measurements of KM-type stars done in the near infrared (1 to 3.5 microns: the JHKL bands of Johnsons's system), with an 83 cm reflector and a PbS detector at La Plata Observatory, we try to establish a new photometric classification system that discriminates luminosity class by means of certain parameters defined by infrared colours and infrared magnitudes. Data compiled and homogenized by J.Koornneef of southern bright stars in those bands were also included. The results give us information about the spectral types and reddening of those stars. We also indicate how to calculate the radiation excess that those stars could have. (author)

  6. Photometric intensity and polarization measurements of the solar corona.

    Science.gov (United States)

    Mcdougal, D. S.

    1971-01-01

    Use of a satellite photometric observatory (SPO) to measure the solar corona from Miahuatlan, Mexico during the Mar. 7, 1970, total eclipse of the sun. The SPO is equipped with a 24-in. Cassegrainian telescope, a four-channel photoelectric photometer, a Wollaston prism, and a rotating half-wave plate. Simultaneous measurements were made of the two orthogonal components of coronal light in the B and R bands of the UBVRI system. A 1-minute arc aperture was scanned from the lunar disk center out to five solar radii in a series of spirals of gradually increasing radius. For the first time, simultaneous multicolor intensity, degree, and angle of polarization profiles are computed from photoelectric measurements. Comparison of the variations of the measurements for each spiral scan yield a detailed picture of the intensity and polarization features in the K corona.

  7. Childhood maltreatment and diurnal cortisol patterns in women with chronic pain.

    Science.gov (United States)

    Nicolson, Nancy A; Davis, Mary C; Kruszewski, Denise; Zautra, Alex J

    2010-06-01

    To assess whether alleged childhood maltreatment is associated with daily cortisol secretion in women with chronic pain. Women with fibromyalgia (FM group, n = 35) or with osteoarthritis only (OA group, n = 35) completed diaries and collected three saliva samples daily for 30 days, with compliance monitored electronically. Childhood abuse and neglect were assessed by self-report (Childhood Trauma Questionnaire-short form [CTQ-sf]). Multilevel regression analyses estimated associations between maltreatment and diurnal cortisol levels and slopes, controlling for depressive symptoms, posttraumatic stress disorder (PTSD), and daily experience variables. Women reporting more severe childhood maltreatment had higher cortisol throughout the day. The estimated effect of CTQ on log cortisol (beta = 0.007, p = .001) represents a 0.7% increase in raw cortisol level for every unit increase in maltreatment score, which ranged from 25 (no maltreatment) to 106 in this sample. Although different forms of maltreatment were interrelated, emotional and sexual abuse were most closely linked to cortisol levels. Fibromyalgia and osteoarthritis groups showed similar secretory patterns, and maltreatment was associated with elevated cortisol in both. Although maltreatment was related to symptoms of depression, PTSD, and averaged daily reports of positive and negative affect, none of these variables mediated the link between maltreatment and cortisol. In women with chronic pain, self-reported childhood maltreatment was associated with higher diurnal cortisol levels. These results add to the evidence that abuse in childhood can induce long-term changes in hypothalamic-pituitary-adrenocortical activity. They further underscore the importance of evaluating childhood maltreatment in fibromyalgia and other chronic pain conditions.

  8. Miniature photometric stereo system for textile surface structure reconstruction

    Science.gov (United States)

    Gorpas, Dimitris; Kampouris, Christos; Malassiotis, Sotiris

    2013-04-01

    In this work a miniature photometric stereo system is presented, targeting the three-dimensional structural reconstruction of various fabric types. This is a supportive module to a robot system, attempting to solve the well known "laundry problem". The miniature device has been designed for mounting onto the robot gripper. It is composed of a low-cost off-the-shelf camera, operating in macro mode, and eight light emitting diodes. The synchronization between image acquisition and lighting direction is controlled by an Arduino Nano board and software triggering. The ambient light has been addressed by a cylindrical enclosure. The direction of illumination is recovered by locating the reflection or the brightest point on a mirror sphere, while a flatfielding process compensates for the non-uniform illumination. For the evaluation of this prototype, the classical photometric stereo methodology has been used. The preliminary results on a large number of textiles are very promising for the successful integration of the miniature module to the robot system. The required interaction with the robot is implemented through the estimation of the Brenner's focus measure. This metric successfully assesses the focus quality with reduced time requirements in comparison to other well accepted focus metrics. Besides the targeting application, the small size of the developed system makes it a very promising candidate for applications with space restrictions, like the quality control in industrial production lines or object recognition based on structural information and in applications where easiness in operation and light-weight are required, like those in the Biomedical field, and especially in dermatology.

  9. Forward Global Photometric Calibration of the Dark Energy Survey

    Science.gov (United States)

    Burke, D. L.; Rykoff, E. S.; Allam, S.; Annis, J.; Bechtol, K.; Bernstein, G. M.; Drlica-Wagner, A.; Finley, D. A.; Gruendl, R. A.; James, D. J.; Kent, S.; Kessler, R.; Kuhlmann, S.; Lasker, J.; Li, T. S.; Scolnic, D.; Smith, J.; Tucker, D. L.; Wester, W.; Yanny, B.; Abbott, T. M. C.; Abdalla, F. B.; Benoit-Lévy, A.; Bertin, E.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Cunha, C. E.; D’Andrea, C. B.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Doel, P.; Estrada, J.; García-Bellido, J.; Gruen, D.; Gutierrez, G.; Honscheid, K.; Kuehn, K.; Kuropatkin, N.; Maia, M. A. G.; March, M.; Marshall, J. L.; Melchior, P.; Menanteau, F.; Miquel, R.; Plazas, A. A.; Sako, M.; Sanchez, E.; Scarpine, V.; Schindler, R.; Sevilla-Noarbe, I.; Smith, M.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Tarle, G.; Walker, A. R.; DES Collaboration

    2018-01-01

    Many scientific goals for the Dark Energy Survey (DES) require the calibration of optical/NIR broadband b = grizY photometry that is stable in time and uniform over the celestial sky to one percent or better. It is also necessary to limit to similar accuracy systematic uncertainty in the calibrated broadband magnitudes due to uncertainty in the spectrum of the source. Here we present a “Forward Global Calibration Method (FGCM)” for photometric calibration of the DES, and we present results of its application to the first three years of the survey (Y3A1). The FGCM combines data taken with auxiliary instrumentation at the observatory with data from the broadband survey imaging itself and models of the instrument and atmosphere to estimate the spatial and time dependences of the passbands of individual DES survey exposures. “Standard” passbands that are typical of the passbands encountered during the survey are chosen. The passband of any individual observation is combined with an estimate of the source spectral shape to yield a magnitude {m}b{std} in the standard system. This “chromatic correction” to the standard system is necessary to achieve subpercent calibrations and in particular, to resolve ambiguity between the broadband brightness of a source and the shape of its SED. The FGCM achieves a reproducible and stable photometric calibration of standard magnitudes {m}b{std} of stellar sources over the multiyear Y3A1 data sample with residual random calibration errors of σ =6{--}7 {mmag} per exposure. The accuracy of the calibration is uniform across the 5000 {\\deg }2 DES footprint to within σ =7 {mmag}. The systematic uncertainties of magnitudes in the standard system due to the spectra of sources are less than 5 {mmag} for main-sequence stars with 0.5< g-i< 3.0.

  10. Forward Global Photometric Calibration of the Dark Energy Survey

    Energy Technology Data Exchange (ETDEWEB)

    Burke, D. L.; Rykoff, E. S.; Allam, S.; Annis, J.; Bechtol, K.; Bernstein, G. M.; Drlica-Wagner, A.; Finley, D. A.; Gruendl, R. A.; James, D. J.; Kent, S.; Kessler, R.; Kuhlmann, S.; Lasker, J.; Li, T. S.; Scolnic, D.; Smith, J.; Tucker, D. L.; Wester, W.; Yanny, B.; Abbott, T. M. C.; Abdalla, F. B.; Benoit-Lévy, A.; Bertin, E.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Cunha, C. E.; D’Andrea, C. B.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Doel, P.; Estrada, J.; García-Bellido, J.; Gruen, D.; Gutierrez, G.; Honscheid, K.; Kuehn, K.; Kuropatkin, N.; Maia, M. A. G.; March, M.; Marshall, J. L.; Melchior, P.; Menanteau, F.; Miquel, R.; Plazas, A. A.; Sako, M.; Sanchez, E.; Scarpine, V.; Schindler, R.; Sevilla-Noarbe, I.; Smith, M.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Tarle, G.; Walker, A. R.

    2017-12-28

    Many scientific goals for the Dark Energy Survey (DES) require calibration of optical/NIR broadband $b = grizY$ photometry that is stable in time and uniform over the celestial sky to one percent or better. It is also necessary to limit to similar accuracy systematic uncertainty in the calibrated broadband magnitudes due to uncertainty in the spectrum of the source. Here we present a "Forward Global Calibration Method (FGCM)" for photometric calibration of the DES, and we present results of its application to the first three years of the survey (Y3A1). The FGCM combines data taken with auxiliary instrumentation at the observatory with data from the broad-band survey imaging itself and models of the instrument and atmosphere to estimate the spatial- and time-dependence of the passbands of individual DES survey exposures. "Standard" passbands are chosen that are typical of the passbands encountered during the survey. The passband of any individual observation is combined with an estimate of the source spectral shape to yield a magnitude $m_b^{\\mathrm{std}}$ in the standard system. This "chromatic correction" to the standard system is necessary to achieve sub-percent calibrations. The FGCM achieves reproducible and stable photometric calibration of standard magnitudes $m_b^{\\mathrm{std}}$ of stellar sources over the multi-year Y3A1 data sample with residual random calibration errors of $\\sigma=5-6\\,\\mathrm{mmag}$ per exposure. The accuracy of the calibration is uniform across the $5000\\,\\mathrm{deg}^2$ DES footprint to within $\\sigma=7\\,\\mathrm{mmag}$. The systematic uncertainties of magnitudes in the standard system due to the spectra of sources are less than $5\\,\\mathrm{mmag}$ for main sequence stars with $0.5

  11. RSO Characterization from Photometric Data Using Machine Learning

    Science.gov (United States)

    Howard, M.; Klem, B.; Gorman, J.

    Object characterization is the description of a resident space object (RSO), its capabilities and its behavior. While astrometric data has been used extensively for object detection, location, and characterization, photometric data has been less widely applied and remains a promising area for improving RSO characterization. RSO characteristics which may influence changes in light intensity with respect to changes in viewing angle or orientation signature include geometry, orientation, components material properties, stability and other characteristics. However, most RSO characterization is presently performed manually and on an individual basis by space analysts and there is a need for efficient and automated methods to perform characterization. This paper discusses the application of machine learning techniques to characterization of RSOs in the geosynchronous altitude regime using photometric data. We develop simulated signatures in the visible spectral band of three basic RSO types, with variations in object orientation, material characteristics, size and attitude and attempt to recover these properties through object characterization techniques. We generate observations by sampling noisy measurements from the simulated signature. Next, we extract a set of features from the observations and train machine learning algorithms to classify the signatures. We consider the effectiveness of a set of binary classifiers trained to individually recognize separate cases. The results of each classifier are combined together to produce a final output characterization of an input observation. Experiments with varying levels of noise are presented, and we evaluate models with respect to classification accuracy and other criteria. The end result of this process is a unique methodology for exploiting the use usefulness and applicability of machine learning to an important space sensing and identification process. This material is based upon work supported by the United States

  12. The Berlin Exoplanet Search Telescope Ii Catalog Of Variable Stars. Ii. Characterization Of The Corot Src02 Field

    Czech Academy of Sciences Publication Activity Database

    Klagyivik, P.; Csizmadia, S.; Pasternacki, T.; Cabrera, J.; Chini, R.; Eigmueller, P.; Erikson, A.; Fruth, T.; Kabáth, Petr; Lemke, R.; Murphy, M.; Rauer, H.; Titz-Weider, R.

    2016-01-01

    Roč. 151, May (2016), 110/1-110/9 ISSN 0004-6256 Institutional support: RVO:67985815 Keywords : eclipsing binaries * variables stars * photometric techniques Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.609, year: 2016

  13. Specific diurnal EMG activity pattern observed in occlusal collapse patients: relationship between diurnal bruxism and tooth loss progression.

    Science.gov (United States)

    Kawakami, Shigehisa; Kumazaki, Yohei; Manda, Yosuke; Oki, Kazuhiro; Minagi, Shogo

    2014-01-01

    The role of parafunctional masticatory muscle activity in tooth loss has not been fully clarified. This study aimed to reveal the characteristic activity of masseter muscles in bite collapse patients while awake and asleep. Six progressive bite collapse patients (PBC group), six age- and gender-matched control subjects (MC group), and six young control subjects (YC group) were enrolled. Electromyograms (EMG) of the masseter muscles were continuously recorded with an ambulatory EMG recorder while patients were awake and asleep. Diurnal and nocturnal parafunctional EMG activity was classified as phasic, tonic, or mixed using an EMG threshold of 20% maximal voluntary clenching. Highly extended diurnal phasic activity was observed only in the PBC group. The three groups had significantly different mean diurnal phasic episodes per hour, with 13.29±7.18 per hour in the PBC group, 0.95±0.97 per hour in the MC group, and 0.87±0.98 per hour in the YC group (pstability.

  14. Diurnal Reflectance Changes in Vegetation Observed with AVIRIS

    Science.gov (United States)

    Vanderbilt, V. C.; Ambrosia, V. G.; Ustin, S. L.

    1998-01-01

    Among the most important short-term dynamic biological processes are diurnal changes in canopy water relations. Plant regulation of water transport through stomatal openings affects other gaseous transport processes, often dramatically decreasing photosynthetic fixation of carbon dioxide during periods of water stress. Water stress reduces stomatal conductance of water vapor through the leaf surface and alters the diurnal timing of stomatal opening. Under non-water stressed conditions, stomates typically open soon after dawn and transpire water vapor throughout the daylight period. During stress periods, stomates may close for part of the day, generally near mid-day. Under prolonged stress conditions, stomatal closure shifts to earlier times during the day; stomates may close by mid-morning and remain closed until the following morning - or remain closed entirely. Under these conditions the relationship between canopy greenness (e.g., measured with a vegetation index or by spectral mixture analysis) and photosynthetic fixation of carbon is lost and the remotely sensed vegetation metric is a poor predictor of gas exchange. Prediction of stomatal regulation and exchange of water and trace gases is critical for ecosystem and climate models to correctly estimate budgets of these gases and understand or predict other processes like gross and net ecosystem primary production. Plant gas exchange has been extensively studied by physiologists at the leaf and whole plant level and by biometeorologists at somewhat larger scales. While these energy driven processes follow a predictable if somewhat asymmetric diurnal cycle dependent on soil water availability and the constraints imposed by the solar energy budget, they are nonetheless difficult to measure at the tree and stand levels using conventional methods. Ecologists have long been interested in the potential of remote sensing for monitoring physiological changes using multi-temporal images. Much of this research has

  15. Searching for I-band variability in stars in the M/L spectral transition region

    Science.gov (United States)

    Ramsay, Gavin; Hakala, Pasi; Doyle, J. Gerry

    2015-10-01

    We report on I-band photometric observations of 21 stars with spectral types between M8 and L4 made using the Isaac Newton Telescope. The total amount of time for observations which had a cadence of test for photometric variability using the Kruskal-Wallis H-test and find that four sources (2MASS J10224821+5825453, 2MASS J07464256+2000321, 2MASS J16262034+3925190 and 2MASS J12464678+4027150) were found to be significantly variable at least on one epoch. Three of these sources are reported as photometrically variable for the first time. If we include sources which were deemed marginally variable, the number of variable sources is 6 (29 per cent). No flares were detected from any source. The percentage of sources which we found were variable is similar to previous studies. We summarize the mechanisms which have been put forward to explain the light curves of brown dwarfs.

  16. Quasar Photometric Redshifts and Candidate Selection: A New Algorithm Based on Optical and Mid-infrared Photometric Data

    Science.gov (United States)

    Yang, Qian; Wu, Xue-Bing; Fan, Xiaohui; Jiang, Linhua; McGreer, Ian; Green, Richard; Yang, Jinyi; Schindler, Jan-Torge; Wang, Feige; Zuo, Wenwen; Fu, Yuming

    2017-12-01

    We present a new algorithm to estimate quasar photometric redshifts (photo-zs), by considering the asymmetries in the relative flux distributions of quasars. The relative flux models are built with multivariate Skew-t distributions in the multidimensional space of relative fluxes as a function of redshift and magnitude. For 151,392 quasars in the SDSS, we achieve a photo-z accuracy, defined as the fraction of quasars with the difference between the photo-z z p and the spectroscopic redshift z s , | {{Δ }}z| =| {z}s-{z}p| /(1+{z}s) within 0.1, of 74%. Combining the WISE W1 and W2 infrared data with the SDSS data, the photo-z accuracy is enhanced to 87%. Using the Pan-STARRS1 or DECaLS photometry with WISE W1 and W2 data, the photo-z accuracies are 79% and 72%, respectively. The prior probabilities as a function of magnitude for quasars, stars, and galaxies are calculated, respectively, based on (1) the quasar luminosity function, (2) the Milky Way synthetic simulation with the Besançon model, and (3) the Bayesian Galaxy Photometric Redshift estimation. The relative fluxes of stars are obtained with the Padova isochrones, and the relative fluxes of galaxies are modeled through galaxy templates. We test our classification method to select quasars using the DECaLS g, r, z, and WISE W1 and W2 photometry. The quasar selection completeness is higher than 70% for a wide redshift range 0.5publicly available.

  17. Photometric and spectroscopic variability of the slow nova V475 Sct (Nova Scuti 2003)

    Czech Academy of Sciences Publication Activity Database

    Chochol, D.; Katysheva, N.A.; Pribulla, T.; Schmidtobreick, L.; Shugarov, S.Yu.; Škoda, Petr; Šlechta, Miroslav; Vittone, A.A.; Volkov, I. M.

    2005-01-01

    Roč. 35, č. 2 (2005), s. 107-129 ISSN 1335-1842 R&D Projects: GA AV ČR KSK2043105 Institutional research plan: CEZ:AV0Z1003909 Keywords : novae * photometry * spectroscopy Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  18. Exploring the Variable Sky with Linear. 1. Photometric Recalibration with the Sloan Digital Sky Survey

    Science.gov (United States)

    2011-12-01

    encoded as a 64-bit integer number theta_2massd Distance in arcsec from the 2MASS source J 2MASS J-band magnitude JErr 2MASS J-band magnitude error H... 2MASS H-band magnitude HErr 2MASS H-band magnitude error K 2MASS K-band magnitude KErr 2MASS K-band magnitude error jh 2MASS J−H color (corrected for...extinction, j − h = (J − 0.327rExt) − (H − 0.209rExt)) hk 2MASS H−K color (corrected for extinction, h− k = (H − 0.209rExt) − (K − 0.133rExt)) jk

  19. Photometric abundances of cepheid variables in the galaxy and the small magellanic cloud

    International Nuclear Information System (INIS)

    Harris, H.C.

    1980-01-01

    Washington system colors and V magnitudes are described for classical and Type II cepheids. The sample includes 102 classical cepheids and 63 Type II cepheids with a wide range of positions in the Galaxy and 45 classical cepheids in the Small Magellanic Cloud. Period-color relations are derived of each type of cepheid and, with period-magnitude relations, are used to determine reddenings and distances. The colors are interpreted in terms of abundances of heavy elements, with a calibration based on observed stars with known abundances and on model-atmosphere colors. The classical cepheids in the Galaxy show a gradient in the Galactic disk of d[A/H]/dR = -0.07 kpc -1 , approximately linear over 10 kpc, small scatter in the abundances of most stars at a given galactocentric radius, and a few stars indicating peculiar abundances. The Type II cepheids show a wide range of abundances with only a small fraction representing a true halo population, a gradient in the abundance distribution with distance from the galactic plane, and at most a weak gradient with distance from the galactic center outside of 2 kpc. Their origin and relation to the metal-rich RR Lyraes is discussed. The cepheids in the SMC show a mean value relative to the Sun of [A/H] = -0.54, with weak evidence that short-period stars are more metal-poor, but with no correlation with projected position in the SMC. The consistency of their colors, temperatures, abundances, and reddenings is discussed

  20. Spectro-photometric calibration of the SuperNova Integral Field Spectrograph in the Nearby Supernova Factory collaboration framework

    International Nuclear Information System (INIS)

    Buton, Clement

    2009-01-01

    Ten years ago, type Ia supernovae used as distances indicators led to the discovery of the accelerating expansion of the universe. Today, a second generation of surveys has significantly increased the high-redshift type Ia supernovae sample. The low-redshift sample was however still limiting the cosmological analysis using SNe. In this framework, the Nearby Supernova Factory has followed 200 nearby type Ia supernovae using the dedicated Supernovae Integral Field Spectrograph with spectro-photometric capacities. My PhD thesis has been carried out at the Institut de Physique Nucleaire de Lyon and at the Lawrence Berkeley National Laboratory in the framework of the international cosmological project SNfactory. In order to reach the design spectrophotometric accuracy, attention has been focused on several key aspects of the calibration procedure, including: determination of a dedicated point spread function for 3D point source extraction, estimating the nightly photometric quality, derivation of the nightly sky extinction over the extended optical domain, its modeling in terms of physical components and its variability within a given night. A full multi-standards calibration pipeline has been implemented using approximately 4000 observations of spectrophotometric standard stars taken throughout the night over nearly 500 individual nights. Preliminary scientific results of the whole SNfactory collaboration will be presented at the end of this thesis. (author)

  1. Data-driven, Interpretable Photometric Redshifts Trained on Heterogeneous and Unrepresentative Data

    Energy Technology Data Exchange (ETDEWEB)

    Leistedt, Boris; Hogg, David W., E-mail: boris.leistedt@nyu.edu, E-mail: david.hogg@nyu.edu [Center for Cosmology and Particle Physics, Department of Physics, New York University, New York, NY 10003 (United States)

    2017-03-20

    We present a new method for inferring photometric redshifts in deep galaxy and quasar surveys, based on a data-driven model of latent spectral energy distributions (SEDs) and a physical model of photometric fluxes as a function of redshift. This conceptually novel approach combines the advantages of both machine learning methods and template fitting methods by building template SEDs directly from the spectroscopic training data. This is made computationally tractable with Gaussian processes operating in flux–redshift space, encoding the physics of redshifts and the projection of galaxy SEDs onto photometric bandpasses. This method alleviates the need to acquire representative training data or to construct detailed galaxy SED models; it requires only that the photometric bandpasses and calibrations be known or have parameterized unknowns. The training data can consist of a combination of spectroscopic and deep many-band photometric data with reliable redshifts, which do not need to entirely spatially overlap with the target survey of interest or even involve the same photometric bands. We showcase the method on the i -magnitude-selected, spectroscopically confirmed galaxies in the COSMOS field. The model is trained on the deepest bands (from SUBARU and HST ) and photometric redshifts are derived using the shallower SDSS optical bands only. We demonstrate that we obtain accurate redshift point estimates and probability distributions despite the training and target sets having very different redshift distributions, noise properties, and even photometric bands. Our model can also be used to predict missing photometric fluxes or to simulate populations of galaxies with realistic fluxes and redshifts, for example.

  2. Data-driven, Interpretable Photometric Redshifts Trained on Heterogeneous and Unrepresentative Data

    International Nuclear Information System (INIS)

    Leistedt, Boris; Hogg, David W.

    2017-01-01

    We present a new method for inferring photometric redshifts in deep galaxy and quasar surveys, based on a data-driven model of latent spectral energy distributions (SEDs) and a physical model of photometric fluxes as a function of redshift. This conceptually novel approach combines the advantages of both machine learning methods and template fitting methods by building template SEDs directly from the spectroscopic training data. This is made computationally tractable with Gaussian processes operating in flux–redshift space, encoding the physics of redshifts and the projection of galaxy SEDs onto photometric bandpasses. This method alleviates the need to acquire representative training data or to construct detailed galaxy SED models; it requires only that the photometric bandpasses and calibrations be known or have parameterized unknowns. The training data can consist of a combination of spectroscopic and deep many-band photometric data with reliable redshifts, which do not need to entirely spatially overlap with the target survey of interest or even involve the same photometric bands. We showcase the method on the i -magnitude-selected, spectroscopically confirmed galaxies in the COSMOS field. The model is trained on the deepest bands (from SUBARU and HST ) and photometric redshifts are derived using the shallower SDSS optical bands only. We demonstrate that we obtain accurate redshift point estimates and probability distributions despite the training and target sets having very different redshift distributions, noise properties, and even photometric bands. Our model can also be used to predict missing photometric fluxes or to simulate populations of galaxies with realistic fluxes and redshifts, for example.

  3. Leveraging 3D-HST Grism Redshifts to Quantify Photometric Redshift Performance

    Science.gov (United States)

    Bezanson, Rachel; Wake, David A.; Brammer, Gabriel B.; van Dokkum, Pieter G.; Franx, Marijn; Labbé, Ivo; Leja, Joel; Momcheva, Ivelina G.; Nelson, Erica J.; Quadri, Ryan F.; Skelton, Rosalind E.; Weiner, Benjamin J.; Whitaker, Katherine E.

    2016-05-01

    We present a study of photometric redshift accuracy in the 3D-HST photometric catalogs, using 3D-HST grism redshifts to quantify and dissect trends in redshift accuracy for galaxies brighter than JH IR > 24 with an unprecedented and representative high-redshift galaxy sample. We find an average scatter of 0.0197 ± 0.0003(1 + z) in the Skelton et al. photometric redshifts. Photometric redshift accuracy decreases with magnitude and redshift, but does not vary monotonically with color or stellar mass. The 1σ scatter lies between 0.01 and 0.03 (1 + z) for galaxies of all masses and colors below z 2), dusty star-forming galaxies for which the scatter increases to ˜0.1 (1 + z). We find that photometric redshifts depend significantly on galaxy size; the largest galaxies at fixed magnitude have photo-zs with up to ˜30% more scatter and ˜5 times the outlier rate. Although the overall photometric redshift accuracy for quiescent galaxies is better than that for star-forming galaxies, scatter depends more strongly on magnitude and redshift than on galaxy type. We verify these trends using the redshift distributions of close pairs and extend the analysis to fainter objects, where photometric redshift errors further increase to ˜0.046 (1 + z) at {H}F160W=26. We demonstrate that photometric redshift accuracy is strongly filter dependent and quantify the contribution of multiple filter combinations. We evaluate the widths of redshift probability distribution functions and find that error estimates are underestimated by a factor of ˜1.1-1.6, but that uniformly broadening the distribution does not adequately account for fitting outliers. Finally, we suggest possible applications of these data in planning for current and future surveys and simulate photometric redshift performance in the Large Synoptic Survey Telescope, Dark Energy Survey (DES), and combined DES and Vista Hemisphere surveys.

  4. The interrelationship between dengue incidence and diurnal ranges of temperature and humidity in a Sri Lankan city and its potential applications.

    Science.gov (United States)

    Ehelepola, N D B; Ariyaratne, Kusalika

    2015-01-01

    Temperature, humidity, and other weather variables influence dengue transmission. Published studies show how the diurnal fluctuations of temperature around different mean temperatures influence dengue transmission. There are no published studies about the correlation between diurnal range of humidity and dengue transmission. The goals of this study were to determine the correlation between dengue incidence and diurnal fluctuations of temperature and humidity in the Sri Lankan city of Kandy and to explore the possibilities of using that information for better control of dengue. We calculated the weekly dengue incidence in Kandy during the period 2003-2012, after collecting data on all of the reported dengue patients and estimated midyear populations. Data on daily maximum and minimum temperatures and night-time and daytime humidity were obtained from two weather stations, averaged, and converted into weekly data. The number of days per week with a diurnal temperature range (DTR) of >10°C and humidity range (DHR) of >20 and humidity. There were negative correlations between dengue incidence and a DTR >10°C and a DHR >20% with 3.3-week and 4-week lag periods, respectively. Additionally, positive correlations between dengue incidence and a DTR humidity in the future. We suggest ways and means to use this information for local dengue control and to mitigate the potential effects of the ongoing global reduction of DTR on dengue incidence.

  5. A Spectroscopic and Photometric Study of Gravitational Microlensing Events

    Science.gov (United States)

    Kane, Stephen R.

    2000-08-01

    Gravitational microlensing has generated a great deal of scientific interest over recent years. This has been largely due to the realization of its wide-reaching applications, such as the search for dark matter, the detection of planets, and the study of Galactic structure. A significant observational advance has been that most microlensing events can be identified in real-time while the source is still being lensed. More than 400 microlensing events have now been detected towards the Galactic bulge and Magellanic Clouds by the microlensing survey teams EROS, MACHO, OGLE, DUO, and MOA. The real-time detection of these events allows detailed follow-up observations with much denser sampling, both photometrically and spectroscopically. The research undertaken in this project on photometric studies of gravitational microlensing events has been performed as a member of the PLANET (Probing Lensing Anomalies NETwork) collaboration. This is a worldwide collaboration formed in the early part of 1995 to study microlensing anomalies - departures from an achromatic point source, point lens light curve - through rapidly-sampled, multi-band, photometry. PLANET has demonstrated that it can achieve 1% photometry under ideal circumstances, making PLANET observations sensitive to detection of Earth-mass planets which require characterization of 1%--2% deviations from a standard microlensing light curve. The photometric work in this project involved over 5 months using the 1.0 m telescope at Canopus Observatory in Australia, and 3 separate observing runs using the 0.9 m telescope at the Cerro Tololo Inter-American Observatory (CTIO) in Chile. Methods were developed to reduce the vast amount of photometric data using the image analysis software MIDAS and the photometry package DoPHOT. Modelling routines were then written to analyse a selection of the resulting light curves in order to detect any deviation from an achromatic point source - point lens light curve. The photometric

  6. Calibration of the photometric method of heavy ion charge measurements in emulsion using a CCD camera

    International Nuclear Information System (INIS)

    Kudzia, D.; Wilczynska, B.; Wilczynski, H.

    2002-01-01

    A previously developed method of heavy ion charge measurements in emulsion has been significantly improved. The charge measurements are based on analysis of photometric profiles of the particle tracks in emulsion. These profiles are obtained using a CCD camera mounted on an optical microscope. So far, the manual charge determination by delta ray counting had to be used for calibration of the photometric method. In this paper a complete procedure for calibration of the photometric method is shown, without resorting to the manual method

  7. Spatial and temporal variations of diurnal ichthyofauna on surf-zone of São Francisco do Itabapoana beaches, Rio de Janeiro State, Brazil

    Directory of Open Access Journals (Sweden)

    Gomes Marcelo Paes

    2003-01-01

    Full Text Available Spatial and temporal variations of diurnal ichthyofauna and the environmental variables influences on its distribution were studied at the surf-zone of three beaches of São Francisco do Itabapoana, northern coast of Rio de Janeiro, Brazil. From August/1999 to August/2000, three beach seine hauls were made monthly, and environmental variables were recorded. A total number of 4,562 fishes (74,155g were sampled at the three beaches, where estuarine-dependent species prevailed (44%, followed by marine (31%, estuarine (19% and freshwater species (3%. Species richness, number of individuals and wet weight were significantly higher at Gargaú, followed by Manguinhos and Barra do Itabapoana, respectively. Canonical Correspondence Analysis highlighted influences of the rivers flushing, salinity and plant abundance on the diurnal ichthyofauna distribution and dynamics of São Francisco do Itabapoana surf-zone.

  8. Moored surface buoy observations of the diurnal warm layer

    KAUST Repository

    Prytherch, J.

    2013-09-01

    An extensive data set is used to examine the dynamics of diurnal warming in the upper ocean. The data set comprises more than 4700 days of measurements at five sites in the tropics and subtropics, obtained from surface moorings equipped to make comprehensive meteorological, incoming solar and infrared radiation, and high-resolution subsurface temperature (and, in some cases, velocity) measurements. The observations, which include surface warmings of up to 3.4°C, are compared with a selection of existing models of the diurnal warm layer (DWL). A simple one-layer physical model is shown to give a reasonable estimate of both the magnitude of diurnal surface warming (model-observation correlation 0.88) and the structure and temporal evolution of the DWL. Novel observations of velocity shear obtained during 346 days at one site, incorporating high-resolution (1 m) upper ocean (5-15 m) acoustic Doppler current profile measurements, are also shown to be in reasonable agreement with estimates from the physical model (daily maximum shear model-observation correlation 0.77). Physics-based improvements to the one-layer model (incorporation of rotation and freshwater terms) are discussed, though they do not provide significant improvements against the observations reported here. The simplicity and limitations of the physical model are used to discuss DWL dynamics. The physical model is shown to give better model performance under the range of forcing conditions experienced across the five sites than the more empirical models. ©2013. American Geophysical Union. All Rights Reserved.

  9. Diurnal Patterns and Correlates of Older Adults' Sedentary Behavior.

    Directory of Open Access Journals (Sweden)

    Jelle Van Cauwenberg

    Full Text Available Insights into the diurnal patterns of sedentary behavior and the identification of subgroups that are at increased risk for engaging in high levels of sedentary behavior are needed to inform potential interventions for reducing older adults' sedentary time. Therefore, we examined the diurnal patterns and sociodemographic correlates of older adults' sedentary behavior(s.Stratified cluster sampling was used to recruit 508 non-institutionalized Belgian older adults (≥ 65 years. Morning, afternoon, evening and total sedentary time was assessed objectively using accelerometers. Specific sedentary behaviors, total sitting time and sociodemographic attributes were assessed using an interviewer-administered questionnaire.Participants self-reported a median of 475 (Q1-Q3 = 383-599 minutes/day of total sitting time and they accumulated a mean of 580 ± 98 minutes/day of accelerometer-derived sedentary time. Sedentary time was lowest during the morning and highest during the evening. Older participants were as sedentary as younger participants during the evening, but they were more sedentary during daytime. Compared to married participants, widowers were more sedentary during daytime. Younger participants (< 75 years, men and the higher educated were more likely to engage in (high levels of sitting while driving a car and using the computer. Those with tertiary education viewed 29% and 22% minutes/day less television compared to those with primary or secondary education, respectively. Older participants accumulated 35 sedentary minutes/day more than did younger participants and men accumulated 32 sedentary minutes/day more than did women.These findings highlight diurnal variations and potential opportunities to tailor approaches to reducing sedentary time for subgroups of the older adult population.

  10. Concerted diurnal patterns in riverine nutrient concentrations and physical conditions

    International Nuclear Information System (INIS)

    Scholefield, David; Le Goff, Thierry; Braven, Jim; Ebdon, Les; Long, Terry; Butler, Mark

    2005-01-01

    Several long-term sets of hourly nitrate concentration data were obtained through deployment of a nitrate sensor in an upper reach of the River Taw, a small moorland-fed river in the South West of the UK. Examination of the data obtained during periods of low flow and the absence of rainfall in the catchment revealed the presence of marked diurnal cycles, which were in concert and negatively correlated with diurnal cycles in water temperature. After verifying that these cycles were natural, an intensive 90-h field monitoring campaign was conducted, in which river water was sampled hourly and immediately analysed in the laboratory for molybdate-reactive phosphorus (P), nitrate, nitrite, ammonium, and pH. Coincident measurements of water temperature, river discharge and solar energy were also taken at, or close to, the site. All measurements revealed diurnal patterns and all patterns were concerted. The cycles of P, nitrate, nitrite, and discharge had two maxima and minima per 24 h, while the cycle of water temperature had one, with a maximum at 20.00 and a minimum at 08.00. The amplitudes of the cycles of P and nitrate were each about 30% of the mean values, while the amplitude of the nitrite cycle was as great as 80% of the mean value on occasions. Both biological and physical mechanisms for the cycling could operate through water temperature and/or incident radiation to account for the observed phenomenon, but there remains uncertainty of which is the more important. The observations have important implications for both the accuracy of pollution assessment in rivers and the physiological rhythms of riverine organisms

  11. Concerted diurnal patterns in riverine nutrient concentrations and physical conditions.

    Science.gov (United States)

    Scholefield, David; Le Goff, Thierry; Braven, Jim; Ebdon, Les; Long, Terry; Butler, Mark

    2005-05-15

    Several long-term sets of hourly nitrate concentration data were obtained through deployment of a nitrate sensor in an upper reach of the River Taw, a small moorland-fed river in the South West of the UK. Examination of the data obtained during periods of low flow and the absence of rainfall in the catchment revealed the presence of marked diurnal cycles, which were in concert and negatively correlated with diurnal cycles in water temperature. After verifying that these cycles were natural, an intensive 90-h field monitoring campaign was conducted, in which river water was sampled hourly and immediately analysed in the laboratory for molybdate-reactive phosphorus (P), nitrate, nitrite, ammonium, and pH. Coincident measurements of water temperature, river discharge and solar energy were also taken at, or close to, the site. All measurements revealed diurnal patterns and all patterns were concerted. The cycles of P, nitrate, nitrite, and discharge had two maxima and minima per 24 h, while the cycle of water temperature had one, with a maximum at 20.00 and a minimum at 08.00. The amplitudes of the cycles of P and nitrate were each about 30% of the mean values, while the amplitude of the nitrite cycle was as great as 80% of the mean value on occasions. Both biological and physical mechanisms for the cycling could operate through water temperature and/or incident radiation to account for the observed phenomenon, but there remains uncertainty of which is the more important. The observations have important implications for both the accuracy of pollution assessment in rivers and the physiological rhythms of riverine organisms.

  12. Moored surface buoy observations of the diurnal warm layer

    KAUST Repository

    Prytherch, J.; Farrar, J. T.; Weller, R. A.

    2013-01-01

    An extensive data set is used to examine the dynamics of diurnal warming in the upper ocean. The data set comprises more than 4700 days of measurements at five sites in the tropics and subtropics, obtained from surface moorings equipped to make comprehensive meteorological, incoming solar and infrared radiation, and high-resolution subsurface temperature (and, in some cases, velocity) measurements. The observations, which include surface warmings of up to 3.4°C, are compared with a selection of existing models of the diurnal warm layer (DWL). A simple one-layer physical model is shown to give a reasonable estimate of both the magnitude of diurnal surface warming (model-observation correlation 0.88) and the structure and temporal evolution of the DWL. Novel observations of velocity shear obtained during 346 days at one site, incorporating high-resolution (1 m) upper ocean (5-15 m) acoustic Doppler current profile measurements, are also shown to be in reasonable agreement with estimates from the physical model (daily maximum shear model-observation correlation 0.77). Physics-based improvements to the one-layer model (incorporation of rotation and freshwater terms) are discussed, though they do not provide significant improvements against the observations reported here. The simplicity and limitations of the physical model are used to discuss DWL dynamics. The physical model is shown to give better model performance under the range of forcing conditions experienced across the five sites than the more empirical models. ©2013. American Geophysical Union. All Rights Reserved.

  13. Modeling the diurnal tide with dissipation derived from UARS/HRDI measurements

    Directory of Open Access Journals (Sweden)

    M. A. Geller

    1997-09-01

    Full Text Available This paper uses dissipation values derived from UARS/HRDI observations in a recently published diurnal-tide model. These model structures compare quite well with the UARS/HRDI observations with respect to the annual variation of the diurnal tidal amplitudes and the size of the amplitudes themselves. It is suggested that the annual variation of atmospheric dissipation in the mesosphere-lower thermosphere is a major controlling factor in determining the annual variation of the diurnal tide.

  14. Does river restoration affect diurnal and seasonal changes to surface water quality? A study along the Thur River, Switzerland

    Energy Technology Data Exchange (ETDEWEB)

    Chittoor Viswanathan, Vidhya [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and Drinking Water, Überlandstrasse 133, 8600 Dübendorf (Switzerland); Université de Neuchâtel, Centre d' Hydrogéologie et de Géothermie (CHYN), Rue Emile-Argand 11, CH-2000 Neuchâtel (Switzerland); Molson, John [Université Laval, Département de Géologie et Génie Géologique, Québec City, Québec (Canada); Schirmer, Mario [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and Drinking Water, Überlandstrasse 133, 8600 Dübendorf (Switzerland); Université de Neuchâtel, Centre d' Hydrogéologie et de Géothermie (CHYN), Rue Emile-Argand 11, CH-2000 Neuchâtel (Switzerland)

    2015-11-01

    Changes in river water quality were investigated along the lower reach of the Thur River, Switzerland, following river restoration and a summer storm event. River restoration and hydrological storm events can each cause dramatic changes to water quality by affecting various bio-geochemical processes in the river, but have to date not been well documented, especially in combination. Evaluating the success of river restoration is often restricted in large catchments due to a lack of high frequency water quality data, which are needed for process understanding. These challenges were addressed in this study by measuring water quality parameters including dissolved oxygen (DO), temperature, pH, electrical conductivity (EC), nitrate and dissolved organic carbon (DOC) with a high temporal frequency (15 min–1 h) over selected time scales. In addition, the stable isotopes of water (δD and δ{sup 18}O-H{sub 2}O) as well as those of nitrate (δ{sup 15}N-NO{sub 3}{sup −} and δ{sup 18}O-NO{sub 3}{sup −}) were measured to follow changes in water quality in response to the hydrological changes in the river. To compare the spatial distribution of pre- and post-restoration water quality, the sampling stations were chosen upstream and downstream of the restored section. The diurnal and seasonal changes were monitored by conducting 24-hour campaigns in three seasons (winter, summer and autumn) in 2012 and 2013. The amplitude of the diurnal changes of the various observed parameters showed significant seasonal and spatial variability. Biological processes — mainly photosynthesis and respiration — were found to be the major drivers of these diurnal cycles. During low flow in autumn, a reduction of nitrate (attributed to assimilation by autotrophs) in the pre-dawn period and a production of DOC during the daytime (attributed to photosynthesis) were observed downstream of the restored site. Further, a summer storm event was found to override the influence of these biological

  15. Does river restoration affect diurnal and seasonal changes to surface water quality? A study along the Thur River, Switzerland

    International Nuclear Information System (INIS)

    Chittoor Viswanathan, Vidhya; Molson, John; Schirmer, Mario

    2015-01-01

    Changes in river water quality were investigated along the lower reach of the Thur River, Switzerland, following river restoration and a summer storm event. River restoration and hydrological storm events can each cause dramatic changes to water quality by affecting various bio-geochemical processes in the river, but have to date not been well documented, especially in combination. Evaluating the success of river restoration is often restricted in large catchments due to a lack of high frequency water quality data, which are needed for process understanding. These challenges were addressed in this study by measuring water quality parameters including dissolved oxygen (DO), temperature, pH, electrical conductivity (EC), nitrate and dissolved organic carbon (DOC) with a high temporal frequency (15 min–1 h) over selected time scales. In addition, the stable isotopes of water (δD and δ 18 O-H 2 O) as well as those of nitrate (δ 15 N-NO 3 − and δ 18 O-NO 3 − ) were measured to follow changes in water quality in response to the hydrological changes in the river. To compare the spatial distribution of pre- and post-restoration water quality, the sampling stations were chosen upstream and downstream of the restored section. The diurnal and seasonal changes were monitored by conducting 24-hour campaigns in three seasons (winter, summer and autumn) in 2012 and 2013. The amplitude of the diurnal changes of the various observed parameters showed significant seasonal and spatial variability. Biological processes — mainly photosynthesis and respiration — were found to be the major drivers of these diurnal cycles. During low flow in autumn, a reduction of nitrate (attributed to assimilation by autotrophs) in the pre-dawn period and a production of DOC during the daytime (attributed to photosynthesis) were observed downstream of the restored site. Further, a summer storm event was found to override the influence of these biological processes that control the diurnal

  16. Diurnal Variation of Radon Concentration in the Postojna Cave

    International Nuclear Information System (INIS)

    Gregoric, A.; Vaupotic, J.

    2011-01-01

    Postojna Cave, with 20 km of galleries, is the longest known cave system and also the largest of about 20 show caves in Slovenia and one of the most visited show caves in the world. It is well known that high concentrations of radon are common in karstic caves, although quantities of uranium (238U) in limestone are rather low. The reason for this is low natural ventilation of the underground cavities. Tectonic faults constitute an additional source of radon. Variations of radon concentration in cave air arise from a balance of the emission from cave surfaces and drip waters, decay in cave air, and exchange with the outside atmosphere. Because of its elevated radon concentrations, Postojna Cave has been under permanent radon survey since 1995. The influence of meteorological conditions on the radon levels and their temporal variations depends mostly on the shape of the cave, and the number and directions of cracks, corridors and fissures connecting the cave rooms with the outside atmosphere. The driving force for air movement in horizontal caves, and thus the inflow of fresh air and release of the cave air to the atmosphere, is the temperature difference between the cave air and outdoors, which causes seasonal pattern of radon concentration in the cave with high levels in summer and low in winter. However, on a daily scale different behaviour of radon can be observed at different locations in the cave. In this paper diurnal variation of radon concentration at two locations is presented and discussed. Postojna Cave is a horizontal cave with a stable yearly temperature around 10 degrees of @C. Continuous measurements of radon concentration were carried out from 2005 to 2010 at two locations along the guided tourist trail. Radon concentration was measured with Radim 5 WP monitors (SMM Company, Prague, Czech Republic) with sampling frequency once an hour. The evaluation of five-year radon monitoring at two sites in the Postojna Cave reveals significant diurnal and

  17. Photometric studies of two solar type marginal contact binaries in the Small Magellanic Cloud

    Science.gov (United States)

    Shanti Priya, Devarapalli; Rukmini, Jagirdar

    2018-04-01

    Using the Optical Gravitational Lensing Experiment catalogue, two contact binaries were studied using data in the V and I bands. The photometric solutions for the V and I bands are presented for two contact binaries OGLE 003835.24-735413.2 (V1) and OGLE 004619.65-725056.2 (V2) in Small Maglellanic Cloud. The presented light curves are analyzed using the Wilson-Devinney code. The results show that the variables are in good thermal and marginal geometrical contact with features like the O’Connell effect in V1. The absolute dimensions are estimated and its dynamical evolution is inferred. They tend to be solar type marginal contact binaries. The 3.6-m Devasthal Optical Telescope and the 4.0-m International Liquid Mirror Telescope of the Aryabhatta Research Institute of Observational Sciences (ARIES, Nainithal) can facilitate the continuous monitoring of such kind of objects which will help in finding the reasons behind their period changes and their impact on the evolution of the clusters.

  18. M DWARFS IN SLOAN DIGITAL SKY SURVEY STRIPE 82: PHOTOMETRIC LIGHT CURVES AND FLARE RATE ANALYSIS

    International Nuclear Information System (INIS)

    Kowalski, Adam F.; Hawley, Suzanne L.; Hilton, Eric J.; Becker, Andrew C.; Sesar, Branimir; West, Andrew A.; Bochanski, John J.

    2009-01-01

    We present a flare rate analysis of 50,130 M dwarf light curves in Sloan Digital Sky Survey Stripe 82. We identified 271 flares using a customized variability index to search ∼2.5 million photometric observations for flux increases in the u and g bands. Every image of a flaring observation was examined by eye and with a point-spread function-matching and image subtraction tool to guard against false positives. Flaring is found to be strongly correlated with the appearance of Hα in emission in the quiet spectrum. Of the 99 flare stars that have spectra, we classify eight as relatively inactive. The flaring fraction is found to increase strongly in stars with redder colors during quiescence, which can be attributed to the increasing flare visibility and increasing active fraction for redder stars. The flaring fraction is strongly correlated with |Z| distance such that most stars that flare are within 300 pc of the Galactic plane. We derive flare u-band luminosities and find that the most luminous flares occur on the earlier-type m dwarfs. Our best estimate of the lower limit on the flaring rate (averaged over Stripe 82) for flares with Δu ≥ 0.7 mag on stars with u -1 deg -2 but can vary significantly with the line of sight.

  19. A Sensitive Photometric Procedure for Cobalt Determination in Water Employing a Compact Multicommuted Flow Analysis System.

    Science.gov (United States)

    da Silva Magalhães, Ticiane; Reis, Boaventura F

    2017-09-01

    In this work, a multicommuted flow analysis procedure is proposed for the spectrophotometric determination of cobalt in fresh water, employing an instrument setup of downsized dimension and improved cost-effectiveness. The method is based on the catalytic effect of Co(II) on the Tiron oxidation by hydrogen peroxide in alkaline medium, forming a complex that absorbs radiation at 425 nm. The photometric detection was accomplished using a homemade light-emitting-diode (LED)-based photometer designed to use a flow cell with an optical path-length of 100 mm to improve sensitivity. After selecting adequate values for the flow system variables, adherence to the Beer-Lambert-Bouguer law was observed for standard solution concentrations in the range of 0.13-1.5 µg L -1 Co(II). Other useful features including a relative standard deviation of 2.0% (n = 11) for a sample with 0.49 µg L -1 Co(II), a detection limit of 0.06 µg L -1 Co(II) (n = 20), an analytical frequency of 42 sample determinations per hour, and waste generation of 1.5 mL per determination were achieved.

  20. Photometric and spectral studies of the eclipsing polar CRTS CSS081231 J071126+440405

    Science.gov (United States)

    Borisov, N. V.; Gabdeev, M. M.; Shimansky, V. V.; Katysheva, N. A.; Kolbin, A. I.; Shugarov, S. Yu.; Goranskij, V. P.

    2016-01-01

    We present the results of the study of the eclipsing polar CRTS CSS081231 J071126+440405. Photometric observations allowed us to refine the orbital period of the system P_ circ = 0_ \\cdot ^d 0.08137673. Considerable changes in the appearance of the object's spectra have occurred over the period of September 20-21, 2001: the slope of the continuum changed from "red" to "blue", and the variability of the line profiles over the duration of the orbital period has also changed. Doppler maps have shown a shift of the emission line-forming region along the accretion stream closer to the white dwarf. We measured the duration of the eclipse of the system and imposed constraints on the inclination angle 78_ \\cdot ^ circ 7 < i < 79_ \\cdot ^ circ 3. The derived radial velocity amplitude was used to obtain the basic parameters of the system: M 1 = 0.86 ± 0.08 M ⊙, M 2 = 0.18 ± 0.02 M ⊙, q = 0.21 ± 0.01, R L2 = 0.20 ± 0.03 R ⊙, A = 0.80 ± 0.03 R ⊙. The spectra of the object exhibit cyclotron harmonics. Their comparison with model spectra allowed us to determine the parameters of the accretion column: B = 31-34 MG, T e = 10-12 keV, θ = 80-90°, and Λ = 105.

  1. Impact of diurnal temperature fluctuations on larval settlement and growth of the reef coral Pocillopora damicornis

    Directory of Open Access Journals (Sweden)

    L. Jiang

    2017-12-01

    Full Text Available Diurnal fluctuations in seawater temperature are ubiquitous on tropical reef flats. However, the effects of such dynamic temperature variations on the early stages of corals are poorly understood. In this study, we investigated the responses of larvae and new recruits of Pocillopora damicornis to two constant temperature treatments (29 and 31 °C and two diurnally fluctuating treatments (28–31 and 30–33 °C with daily means of 29 and 31 °C, respectively simulating the 3 °C diel oscillations at 3 m depth on the Luhuitou fringing reef (Sanya, China. Results showed that the thermal stress on settlement at 31 °C was almost negated by the fluctuating treatment. Further, neither elevated temperature nor temperature fluctuations caused bleaching responses in recruits, while the maximum excitation pressure over photosystem II (PSII was reduced under fluctuating temperatures. Although early growth and development were highly stimulated at 31 °C, oscillations of 3 °C had little effects on budding and lateral growth at either mean temperature. Nevertheless, daytime encounters with the maximum temperature of 33 °C in fluctuating 31 °C elicited a notable reduction in calcification compared to constant 31 °C. These results underscore the complexity of the effects caused by diel temperature fluctuations on early stages of corals and suggest that ecologically relevant temperature variability could buffer warming stress on larval settlement and dampen the positive effects of increased temperatures on coral growth.

  2. Polymorphism in the PER3 promoter associates with diurnal preference and delayed sleep phase disorder.

    Science.gov (United States)

    Archer, Simon N; Carpen, Jayshan D; Gibson, Mark; Lim, Gim Hui; Johnston, Jonathan D; Skene, Debra J; von Schantz, Malcolm

    2010-05-01

    To screen the PER3 promoter for polymorphisms and investigate the phenotypic associations of these polymorphisms with diurnal preference, delayed sleep phase disorder/syndrome (DSPD/DSPS), and their effects on reporter gene expression. Interspecific comparison was used to define the approximate extent of the PER3 promoter as the region between the transcriptional start site and nucleotide position -874. This region was screened in DNA pools using PCR and direct sequencing, which was also used to screen DNA from individual participants. The different promoter alleles were cloned into a luciferase expression vector and a deletion library created. Promoter activation was measured by chemiluminescence. N/A. DNA samples were obtained from volunteers with defined diurnal preference (3 x 80, selected from a pool of 1,590), and DSPD patients (n=23). N/A. We verified three single nucleotide polymorphisms (G -320T, C -319A, G -294A), and found a novel variable number tandem repeat (VNTR) polymorphism (-318 1/2 VNTR). The -320T and -319A alleles occurred more frequently in DSPD compared to morning (P = 0.042 for each) or evening types (P = 0.006 and 0.033). The allele combination TA2G was more prevalent in DSPD compared to morning (P 0.033) or evening types (P = 0.002). Luciferase expression driven by the TA2G combination was greater than for the more common GC2A (P < 0.05) and the rarer TA1G (P < 0.001) combinations. Deletion reporter constructs identified two enhancer regions (-703 to -605, and -283 to -80). Polymorphisms in the PER3 promoter could affect its expression, leading to potential differences in the observed functions of PER3.

  3. Diurnal and Reproductive Stage-Dependent Variation of Parental Behaviour in Captive Zebra Finches.

    Directory of Open Access Journals (Sweden)

    Boglárka Morvai

    Full Text Available Parental care plays a key role in ontogeny, life-history trade-offs, sexual selection and intra-familial conflict. Studies focusing on understanding causes and consequences of variation in parental effort need to quantify parental behaviour accurately. The applied methods are, however, diverse even for a given species and type of parental effort, and rarely validated for accuracy. Here we focus on variability of parental behaviour from a methodological perspective to investigate the effect of different samplings on various estimates of parental effort. We used nest box cameras in a captive breeding population of zebra finches, Taeniopygia guttata, a widely used model system of sexual selection, intra-familial dynamics and parental care. We investigated diurnal and reproductive stage-dependent variation in parental effort (including incubation, brooding, nest attendance and number of feedings based on 12h and 3h continuous video-recordings taken at various reproductive stages. We then investigated whether shorter (1h sampling periods provided comparable estimates of overall parental effort and division of labour to those of longer (3h sampling periods. Our study confirmed female-biased division of labour during incubation, and showed that the difference between female and male effort diminishes with advancing reproductive stage. We found individually consistent parental behaviours within given days of incubation and nestling provisioning. Furthermore, parental behaviour was consistent over the different stages of incubation, however, only female brooding was consistent over nestling provisioning. Parental effort during incubation did not predict parental effort during nestling provisioning. Our analyses revealed that 1h sampling may be influenced heavily by stochastic and diurnal variation. We suggest using a single longer sampling period (3h may provide a consistent and accurate estimate for overall parental effort during incubation in zebra

  4. Hawk eyes II: diurnal raptors differ in head movement strategies when scanning from perches.

    Science.gov (United States)

    O'Rourke, Colleen T; Pitlik, Todd; Hoover, Melissa; Fernández-Juricic, Esteban

    2010-09-22

    Relatively little is known about the degree of inter-specific variability in visual scanning strategies in species with laterally placed eyes (e.g., birds). This is relevant because many species detect prey while perching; therefore, head movement behavior may be an indicator of prey detection rate, a central parameter in foraging models. We studied head movement strategies in three diurnal raptors belonging to the Accipitridae and Falconidae families. We used behavioral recording of individuals under field and captive conditions to calculate the rate of two types of head movements and the interval between consecutive head movements. Cooper's Hawks had the highest rate of regular head movements, which can facilitate tracking prey items in the visually cluttered environment they inhabit (e.g., forested habitats). On the other hand, Red-tailed Hawks showed long intervals between consecutive head movements, which is consistent with prey searching in less visually obstructed environments (e.g., open habitats) and with detecting prey movement from a distance with their central foveae. Finally, American Kestrels have the highest rates of translational head movements (vertical or frontal displacements of the head keeping the bill in the same direction), which have been associated with depth perception through motion parallax. Higher translational head movement rates may be a strategy to compensate for the reduced degree of eye movement of this species. Cooper's Hawks, Red-tailed Hawks, and American Kestrels use both regular and translational head movements, but to different extents. We conclude that these diurnal raptors have species-specific strategies to gather visual information while perching. These strategies may optimize prey search and detection with different visual systems in habitat types with different degrees of visual obstruction.

  5. Near Real-Time Photometric Data Processing for the Solar Mass Ejection Imager (SMEI)

    Science.gov (United States)

    Hick, P. P.; Buffington, A.; Jackson, B. V.

    2004-12-01

    The Solar Mass Ejection Imager (SMEI) records a photometric white-light response of the interplanetary medium from Earth over most of the sky in near real time. In the first two years of operation the instrument has recorded the inner heliospheric response to several hundred CMEs, including the May 28, 2003 and the October 28, 2003 halo CMEs. In this preliminary work we present the techniques required to process the SMEI data from the time the raw CCD images become available to their final assembly in photometrically accurate maps of the sky brightness relative to a long-term time base. Processing of the SMEI data includes integration of new data into the SMEI data base; a conditioning program that removes from the raw CCD images an electronic offset ("pedestal") and a temperature-dependent dark current pattern; an "indexing" program that places these CCD images onto a high-resolution sidereal grid using known spacecraft pointing information. At this "indexing" stage further conditioning removes the bulk of the the effects of high-energy-particle hits ("cosmic rays"), space debris inside the field of view, and pixels with a sudden state change ("flipper pixels"). Once the high-resolution grid is produced, it is reformatted to a lower-resolution set of sidereal maps of sky brightness. From these sidereal maps we remove bright stars, background stars, and a zodiacal cloud model (their brightnesses are retained as additional data products). The final maps can be represented in any convenient sky coordinate system. Common formats are Sun-centered Hammer-Aitoff or "fisheye" maps. Time series at selected locations on these maps are extracted and processed further to remove aurorae, variable stars and other unwanted signals. These time series (with a long-term base removed) are used in 3D tomographic reconstructions. The data processing is distributed over multiple PCs running Linux, and, runs as much as possible automatically using recurring batch jobs ('cronjobs'). The

  6. An Assessment of GEO Orbital Debris Photometric Properties Derived from Laboratory-Based Measurements

    Science.gov (United States)

    Rodriquez-Cowardin, H.; Abercromby, K.; Barker, E.; Mulrooney, M.; Seitzer, P.; Schildknecht, T.

    2009-01-01

    Optical observations of orbital debris offer insights that differ from radar measurements (specifically the size parameter and wavelength regime). For example, time-dependent photometric data yield lightcurves in multiple bandpasses that aid in material identification and possible periodic orientations. This data can also be used to help identify shapes and optical properties at multiple phase angles. Capitalizing on optical data products and applying them to generate a more complete understanding of orbital space objects, is a key objective of NASA s Optical Measurement Program, and a primary driver for creation of the Optical Measurements Center (OMC). The OMC attempts to emulate space-based illumination conditions using equipment and techniques that parallel telescopic observations and source-target-sensor orientations. The OMC uses a 300 Watt Xenon arc lamp as a solar simulator, a CCD camera with Johnson/Bessel colored filters, and a robotic arm to orientate/rotate objects to simulate an object's orbit/rotational period. A high-resolution, high bandwidth (350nm-2500nm) Analytical Spectral Devices (ASD) spectrometer is also employed to baseline various material types. Since observation of GEO targets are generally restricted to the optical regime (due to radar range limitations), analysis of their properties is tailored to those revealed by optical data products. In this connection, much attention has been directed towards understanding the lightcurves of orbital debris with high area-to-mass (A/m) ratios (greater than 0.9 square meters per kilogram). A small population of GEO debris was recently identified, which exhibits the properties of high A/m objects, such as variable eccentricities and inclinations a dynamical characteristic generally resulting from varying solar radiation pressure on high A/m objects. Materials such as multi-layered insulation (MLI) and solar panels are two examples of materials with high area-to mass ratios. Lightcurves for such

  7. QUEST1 Variability Survey. II. Variability Determination Criteria and 200k Light Curve Catalog

    Science.gov (United States)

    Rengstorf, A. W.; Mufson, S. L.; Andrews, P.; Honeycutt, R. K.; Vivas, A. K.; Abad, C.; Adams, B.; Bailyn, C.; Baltay, C.; Bongiovanni, A.; Briceño, C.; Bruzual, G.; Coppi, P.; Della Prugna, F.; Emmet, W.; Ferrín, I.; Fuenmayor, F.; Gebhard, M.; Hernández, J.; Magris, G.; Musser, J.; Naranjo, O.; Oemler, A.; Rosenzweig, P.; Sabbey, C. N.; Sánchez, Ge.; Sánchez, Gu.; Schaefer, B.; Schenner, H.; Sinnott, J.; Snyder, J. A.; Sofia, S.; Stock, J.; van Altena, W.

    2004-12-01

    The QUEST (QUasar Equatorial Survey Team) Phase 1 camera has collected multibandpass photometry on a large strip of high Galactic latitude sky over a period of 26 months. This robust data set has been reduced and nightly catalogs compared to determine the photometric variability of the ensemble objects. Subsequent spectroscopic observations have confirmed a subset of the photometric variables as quasars, as previously reported. This paper reports on the details of the data reduction and analysis pipeline and presents multiple bandpass light curves for 198,213 QUEST1 objects, along with global variability information and matched Sloan photometry. Based on observations obtained at the Llano del Hato National Astronomical Observatory, operated by the Centro de Investigaciones de Astronomía for the Ministerio de Ciencia y Tecnologia of Venezuela.

  8. Creation of a Unified Set of Core-Collapse Supernovae for Training of Photometric Classifiers

    Science.gov (United States)

    D'Arcy Kenworthy, William; Scolnic, Daniel; Kessler, Richard

    2017-01-01

    One of the key tasks for future supernova cosmology analyses is to photometrically distinguish type Ia supernovae (SNe) from their core collapse (CC) counterparts. In order to train programs for this purpose, it is necessary to train on a large number of core-collapse SNe. However, there are only a handful used for current programs. We plan to use the large amount of CC lightcurves available on the Open Supernova Catalog (OSC). Since this data is scraped from many different surveys, it is given in a number of photometric systems with different calibration and filters. We therefore created a program to fit smooth lightcurves (as a function of time) to photometric observations of arbitrary SNe. The Supercal method is then used to translate the smoothed lightcurves to a single photometric system. We can thus compile a training set of 782 supernovae, of which 127 are not type Ia. These smoothed lightcurves are also being contributed upstream to the OSC as derived data.

  9. Photometry of long-period Algol binaries. VI. Multicolor photometric solutions for RZ Cancri

    International Nuclear Information System (INIS)

    Olson, E.C.

    1989-01-01

    New intermediate-band photometry of the late-giant eclipsing system RZ CNc is used to obtain photometric solutions, both with the Popper (1976) spectroscopic mass ratio and by allowing the mass ratio and gravity-darkening coefficients to vary. New y observations are combined with earlier V data of Lenouvel (1957) and Broglia and Conconi (1973) in one solution set. Additional solutions are obtained from the new observations. The mean photometric mass ratio is somewhat larger than Popper's spectroscopic values; the general indeterminacy of photometric solutions may explain this apparent discrepancy. Possible photometric effects of a mass-transferring stream are discussed, and it is concluded that such effects cannot account for the mass-ratio discrepancy. 26 refs

  10. Photometry of long-period Algol binaries. VI. Multicolor photometric solutions for RZ Cancri

    Energy Technology Data Exchange (ETDEWEB)

    Olson, E.C. (Illinois Univ., Urbana (USA))

    1989-09-01

    New intermediate-band photometry of the late-giant eclipsing system RZ CNc is used to obtain photometric solutions, both with the Popper (1976) spectroscopic mass ratio and by allowing the mass ratio and gravity-darkening coefficients to vary. New y observations are combined with earlier V data of Lenouvel (1957) and Broglia and Conconi (1973) in one solution set. Additional solutions are obtained from the new observations. The mean photometric mass ratio is somewhat larger than Popper's spectroscopic values; the general indeterminacy of photometric solutions may explain this apparent discrepancy. Possible photometric effects of a mass-transferring stream are discussed, and it is concluded that such effects cannot account for the mass-ratio discrepancy. 26 refs.

  11. Standard Test Method for Solar Photometric Transmittance of Sheet Materials Using Sunlight

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1996-01-01

    1.1 This test method covers the measurement of solar photometric transmittance of materials in sheet form. Solar photometric transmittance is measured using a photometer (illuminance meter) in an enclosure with the sun and sky as the source of radiation. The enclosure and method of test is specified in Test Method E 1175 (or Test Method E 1084). 1.2 The purpose of this test method is to specify a photometric sensor to be used with the procedure for measuring the solar photometric transmittance of sheet materials containing inhomogeneities in their optical properties. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  12. The walraven VBLUW photometric system : 32 years of 5-channel photometry

    NARCIS (Netherlands)

    Pel, Jan Willem; Lub, Jan; Sterken, C

    2007-01-01

    An overview is given of the Walraven V BLUW photometric system. We concentrate on the aspects of stability, internal and external precison of the standard system, flux calibration and theoretical model grids.

  13. Improving photometric redshift estimation using GPZ: size information, post processing, and improved photometry

    Science.gov (United States)

    Gomes, Zahra; Jarvis, Matt J.; Almosallam, Ibrahim A.; Roberts, Stephen J.

    2018-03-01

    The next generation of large-scale imaging surveys (such as those conducted with the Large Synoptic Survey Telescope and Euclid) will require accurate photometric redshifts in order to optimally extract cosmological information. Gaussian Process for photometric redshift estimation (GPZ) is a promising new method that has been proven to provide efficient, accurate photometric redshift estimations with reliable variance predictions. In this paper, we investigate a number of methods for improving the photometric redshift estimations obtained using GPZ (but which are also applicable to others). We use spectroscopy from the Galaxy and Mass Assembly Data Release 2 with a limiting magnitude of r Program Data Release 1 and find that it produces significant improvements in accuracy, similar to the effect of including additional features.

  14. Photometric study of the eclipsing binary U Sagittae

    International Nuclear Information System (INIS)

    McNamara, D.H.; Feltz, K.A. Jr.

    1976-01-01

    The geometric and photometric elements of the eclipsing star U Sge have been derived from uvby observations secured in 1973-74. The ''best'' elements are r 1 = 0.296, r 2 = 0.225, i = 90 0 ; and L 1 = 0.130, L 2 = 0.870 in yellow light where the subscript 1 refers to the G2 IV-III component and the subscript 2 refers to the B8 V component. Radii and masses of the two stars can be derived by assuming that the larger star fills its Roche lobe. This assumption yields r 1 = 3.32 R/sub solar mass/, r 2 = 2.52 R/sub solar mass/, M 1 = 1.4 solar mass, and M 2 = 3.5 solar mass. The absolute magnitudes are found by two different methods and yield M/sub v/ = -0/sup m/4 for the B star and M/sub v/ = + 1.8/sup m/ for the G star. If corrections for radiative interactions are made, the absolute magnitude of the G star is M/sub v/ is approximately equal + 2.2/sup m/. Observational data secured in the u filter suggest that Balmer continuum emission can be detected from an emitting gas stream or disk. The gas must be concentrated near the following hemisphere of the B Star. The m 1 measurements of the secondary component suggest a metal deficiency of [Fe/H] = -0.6

  15. Bifurcations in two-image photometric stereo for orthogonal illuminations

    Science.gov (United States)

    Kozera, R.; Prokopenya, A.; Noakes, L.; Śluzek, A.

    2017-07-01

    This paper discusses the ambiguous shape recovery in two-image photometric stereo for a Lambertian surface. The current uniqueness analysis refers to linearly independent light-source directions p = (0, 0, -1) and q arbitrary. For this case necessary and sufficient condition determining ambiguous reconstruction is governed by a second-order linear partial differential equation with constant coefficients. In contrast, a general position of both non-colinear illumination directions p and q leads to a highly non-linear PDE which raises a number of technical difficulties. As recently shown, the latter can also be handled for another family of orthogonal illuminations parallel to the OXZ-plane. For the special case of p = (0, 0, -1) a potential ambiguity stems also from the possible bifurcations of sub-local solutions glued together along a curve defined by an algebraic equation in terms of the data. This paper discusses the occurrence of similar bifurcations for such configurations of orthogonal light-source directions. The discussion to follow is supplemented with examples based on continuous reflectance map model and generated synthetic images.

  16. Infrared photometric behavior and opposition effect of Mars

    Science.gov (United States)

    Erard, S.; Bibring, J-P.; Drossart, P.

    1992-01-01

    Although the instrument wasn't designed for this purpose, data from the imaging spectrometer ISM may be used for studying photometric variations of Mars reflectance, that are related to the surface materials and aerosols physical properties. ISM flew aboard the Phobos-2 spacecraft which orbited Mars from January to March, 1989. About 40,000 spectra were acquired in 128 channels ranging from 0.76 to 3.16 micro-m, with a spatial resolution of 25 km and a signal-to-noise ratio ranging up to 1000. Analysis of the results leads to the following conclusions: width variations of the opposition surge can be related to differences in porosity or grain size distribution on the various domains, with little or no effect from suspended dust. As the biggest effects are observed on dark and bright materials, intermediate behaviors on average-bright regions cannot result from a mixing process, but are more likely to come from either cementation processes or modification of the grain size distribution under the influence of wind, which under Martian conditions preferentially removes the biggest particles. Thus, a surface dust consisting in big bright and small dark grains could explain the observations.

  17. Unexpected Far-Ultraviolet Photometric Characteristics On Mimas

    Science.gov (United States)

    Royer, E. M.; Hendrix, A. R.

    2013-12-01

    While infrared and visible are the most common wavelength domains used to investigate planetary surfaces, ultraviolet (UV) data are significant and useful. Here, we present the first far-UV phase curves of Mimas, thus displaying another piece of the Saturnian System puzzle. Our preliminary results shows that, one more time, Mimas surface properties are far from what we was expected. Namely, we observe a leading hemisphere brighter than the trailing hemisphere at some far-UV wavelengths. We used the far-UV channel of the Cassini/UVIS instrument, ranging from 118 to 190 nm. Disk-integrated phase curves for the leading hemisphere and the trailing hemisphere, at 180nm, have been produced. Data points span from 0.5 to 163.5 degrees in phase angle. Mimas displays a leading hemisphere brighter than its trailing hemisphere, when theory and previous Voyager observations at longer wavelengths attest of a brighter trailing hemisphere due to the impact of the E-ring grains on this face of the satellite. Surprisingly, UVIS data show a very bright opposition effect on Mimas leading hemisphere, greater than what is observed on Tethys or Dione leading hemisphere at the same wavelength of 180 nm. Preliminary results of photometric properties modeling seem to indicate an important contribution of the coherent-backscattering process in the opposition surge. Exogenic processes such as bombardment by energetic electrons and/or E-ring grains are discussed to explain this unexpected surface property of Mimas.

  18. The SDSS Coadd: A Galaxy Photometric Redshift Catalog

    Energy Technology Data Exchange (ETDEWEB)

    Reis, Ribamar R.R.; /Fermilab /Rio de Janeiro Federal U.; Soares-Santos, Marcelle; /Fermilab /Inst. Geo. Astron., Havana /Sao Paulo U.; Annis, James; /Fermilab; Dodelson, Scott; /Fermilab /Chicago U. /Chicago U., KICP; Hao, Jiangang; /Fermilab; Johnston, David; /Fermilab; Kubo, Jeffrey; /Fermilab; Lin, Huan; /Fermilab; Seo, Hee-Jong; /UC, Berkeley; Simet, Melanie; /Chicago U.

    2011-11-01

    We present and describe a catalog of galaxy photometric redshifts (photo-z's) for the Sloan Digital Sky Survey (SDSS) Coadd Data. We use the Artificial Neural Network (ANN) technique to calculate photo-z's and the Nearest Neighbor Error (NNE) method to estimate photo-z errors for {approx} 13 million objects classified as galaxies in the coadd with r < 24.5. The photo-z and photo-z error estimators are trained and validated on a sample of {approx} 89, 000 galaxies that have SDSS photometry and spectroscopic redshifts measured by the SDSS Data Release 7 (DR7), the Canadian Network for Observational Cosmology Field Galaxy Survey (CNOC2), the Deep Extragalactic Evolutionary Probe Data Release 3(DEEP2 DR3), the SDSS-III's Baryon Oscillation Spectroscopic Survey (BOSS), the Visible imaging Multi-Object Spectrograph - Very Large Telescope Deep Survey (VVDS) and the WiggleZ Dark Energy Survey. For the best ANN methods we have tried, we find that 68% of the galaxies in the validation set have a photo-z error smaller than {sigma}{sub 68} = 0.036. After presenting our results and quality tests, we provide a short guide for users accessing the public data.

  19. Reduction and analysis of photometric data on Comet Halley

    International Nuclear Information System (INIS)

    Belton, M.J.S.; Fink, U.; Wehinger, P.; Spinrad, H.; Meech, K.

    1988-01-01

    The discovery that periodic variations in the brightness of Comet Halley were characterized by two unrelated frequencies implies that the nucleus is in a complex state of rotation. It either nutates as a result of the random addition of small torque perturbations accumulated over many perihelion passages, or the jet activity torques are so strong that it precesses wildly at each perihelion passage. To diagnose the state of nuclear rotation, researchers began a program to acquire photometric time series of the comet as it recedes from the sun. The intention is to observe the decay of the comet's atmosphere and then, when it is unemcumbered by the light of the coma, follow the light variation of the nucleus itself. The latter will be compared with preperihelion time series and the orientation of the nucleus at the time of Vega and Giotto flybys and an accurate rotational ephemeris constructed. Halley was observed on 38 nights during 1987 and approximately 21 nights in 1988. The comet moved from 5 AU to 8.5 AU during this time. The brightness of the coma was found to rapidly decrease in 1988 as the coma and cometary activity collapses. The magnitude in April 1988 was 19 mag (visual) and it is predicted that the nucleus itself will be the major contributor to the brightness in the 1988 and 1989 season