Lessons learned from ESA INTEGRAL: cataclysmic variables and blazars

Czech Academy of Sciences Publication Activity Database

Hudec, René; Gális, R.; Kocka, Matúš

2010-01-01

Roč. 81, č. 1 (2010), s. 320-325 ISSN 0037-8720. [Multifrequency behaviour of high energy cosmic sources. Vulcano, 25.05.2009-30.05. 2009] Institutional research plan: CEZ:AV0Z10030501 Keywords : high-energy sources * cataclysmic variables * INTEGRAL Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

CVcat: An interactive database on cataclysmic variables

Science.gov (United States)

Kube, J.; Gänsicke, B. T.; Euchner, F.; Hoffmann, B.

2003-06-01

CVcat is a database that contains published data on cataclysmic variables and related objects. Unlike in the existing online sources, the users are allowed to add data to the catalogue. The concept of an ``open catalogue'' approach is reviewed together with the experience from one year of public usage of CVcat. New concepts to be included in the upcoming AstroCat framework and the next CVcat implementation are presented. CVcat can be found at http://www.cvcat.org.

White-dwarf rotational equilibria in magnetic cataclysmic variable stars

Energy Technology Data Exchange (ETDEWEB)

Warner, B. (Cape Town Univ. (South Africa). Dept. of Astronomy Australian National Univ., Canberra (Australia). Dept. of Mathematics); Wickramasinghe, D.T. (Australian National Univ., Canberra (Australia). Dept. of Mathematics)

1991-02-01

The magnetic cataclysmic variable stars (polars, intermediate polars and DQ Her stars) are grouped about three lines in the orbital period-spin period diagram. This segregation is shown to be the consequence of competition between braking and accretion torques when combined with the effects of cyclical variations in rate of mass transfer. (author).

White dwarf models of supernovae and cataclysmic variables

International Nuclear Information System (INIS)

Nomoto, K.; Hashimoto, M.

1986-01-01

If the accreting white dwarf increases its mass to the Chandrasekhar mass, it will either explode as a Type I supernova or collapse to form a neutron star. In fact, there is a good agreement between the exploding white dwarf model for Type I supernovae and observations. We describe various types of evolution of accreting white dwarfs as a function of binary parameters (i.e,. composition, mass, and age of the white dwarf, its companion star, and mass accretion rate), and discuss the conditions for the precursors of exploding or collapsing white dwarfs, and their relevance to cataclysmic variables. Particular attention is given to helium star cataclysmics which might be the precursors of some Type I supernovae or ultrashort period x-ray binaries. Finally we present new evolutionary calculations using the updated nuclear reaction rates for the formation of O+Ne+Mg white dwarfs, and discuss the composition structure and their relevance to the model for neon novae. 61 refs., 14 figs

Observing cataclysmic variables and related objects with different techniques

Czech Academy of Sciences Publication Activity Database

Šimon, Vojtěch

2012-01-01

Roč. 83, č. 2 (2012), s. 675-682 ISSN 0037-8720. [Workshop on the golden age of cataclysmic variables and related objects /2./. Palermo , 09.09.2013-14.09.2013] R&D Projects: GA ČR GA205/08/1207 Institutional research plan: CEZ:AV0Z10030501 Keywords : X-rays * binaries * circumstellar matter Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

The intermediate-age pre-cataclysmic variables SDSS J172406+562003 and RE J2013+4002

Science.gov (United States)

Shimansky, V. V.; Borisov, N. V.; Nurtdinova, D. N.; Mitrofanova, A. A.; Vlasyuk, V. V.; Spiridonova, O. I.

2012-06-01

We have analyzed the physical status of the pre-cataclysmic variables SDSSJ172406+562003 and RE J2013+4002, which have evolved after their common-envelope stage a time t = 106-107 years. Spectroscopy and photometry of these systems were performed with the 6-m and 1-m telescopes of the Special Astrophysical Observatory. We demonstrate that emission lines in the spectra were formed solely by the reflection of radiation emitted by the white dwarfs on the surfaces of their cool companions, under conditions close to local thermodynamic equilibrium. These effects are also responsible for most of the objects' photometric variability amplitude. However, comparing the light curves of SDSS 172406 from different epochs, we find aperiodic brightness variations, probably due to spottedness of the surface of the secondary. Jointly analyzing the spectra, radial-velocity curves, and light curves of the pre-cataclysmic variables and modeling the reflection effects, we have derived their fundamental parameters. We demonstrate that the secondaries in these systems are consistent with evolutionary models for main-sequence stars and do not have the luminosity excesses characteristic of cool stars in young pre-cataclysmic variables.

On the masses of the white dwarfs in cataclysmic variables

International Nuclear Information System (INIS)

Livio, M.; Soker, N.

1984-01-01

The question of the masses of the white dwarfs in cataclysmic binaries is examined. It is shown that selection effects can explain an overabundance of massive white dwarfs in novae but not in dwarf novae. It is proposed that the spiralling-in process in the common envelope favours the formation of more massive white dwarfs A number of simplified spiralling-in calculations are performed. The calculations demonstrate that the probability of coalescence of the secondary with the primary core, or secondary dissipation, is higher in the case of a giant envelope than in the case of a super giant envelope. Consequently, binaries with primary core masses greater than approx. 0.7 Msolar masses (and thus massive white dwarf remnants), have a better chance of surviving common envelope evolution and are therefore better candidates for the formation of cataclysmic variables. (author)

Evolution and Outbursts of Cataclysmic Variables

Directory of Open Access Journals (Sweden)

S.-B. Qian

2015-02-01

Full Text Available Mass transfer and accretion are very important to understand the evolution and observational properties of cataclysmic variables (CVs. Due to the lack of an accretion disk, eclipsing profiles of polars are the best source to study the character of mass transfer in CVs. By analyzing long-term photometric variations in the eclipsing polar HU Aqr, the property of mass transfer and accretion are investigated. The correlation between the brightness state change and the variation of the ingress profile suggests that both the accretion hot spot and the accretion stream are produced instantaneously. The observations clearly show that it is the variation of mass transfer causing the brightness state changes that is a direct evidence of variable mass transfer in a CV. It is shown that it is the local dark-spot activity near the L1 point to cause the change of the mass transfer rather than the activity cycles of the cool secondary star. Our results suggest that the evolution of CVs is more complex than that predicted by the standard model and we should consider the effect of variable mass accretion in nova and dwarf nova outbursts.

Winds in cataclysmic variable stars

International Nuclear Information System (INIS)

Cordova, F.A.; Ladd, E.F.; Mason, K.O.

1984-01-01

Ultraviolet spectrophotometry of two dwarf novae, CN Ori and RX And, at various phases of their outburst cycles confirms that the far uv flux increases dramatically about 1-2 days after the optical outburst begins. At this time the uv spectral line profiles indicate the presence of a high velocity wind. The detectability of the wind depends more on the steepness of the spectrum, and thus on the flux in the extreme ultraviolet, than on the absolute value of the far uv luminosity. The uv continuum during outburst consists of (at least) two components, the most luminous of which is located behind the wind and is completely absorbed by the wind at the line frequencies. Several pieces of evidence suggest that the uv emission lines that are observed in many cataclysmic variables during quiescence have a different location in the binary than the wind, and are affected very little by the outburst

Cataclysmic variables as probes of x-ray properties of interstellar grains

International Nuclear Information System (INIS)

Bode, M.F.; Evans, A.; Norwell, G.A.

1983-01-01

Interstellar-grain properties have previously been probed at wavelengths ranging from the infrared to the ultraviolet. Recent work by other authors has shown that we may also observe the effects of scattering by such grains at x-ray wavelengths. In this paper we suggest that investigations of the x-ray properties of interstellar grains may profitably be conducted in sight lines to variable sources. Particular emphasis is given in this context to cataclysmic variables and related objects

The X-ray cataclysmic variable 1E0643.0-1648

International Nuclear Information System (INIS)

Bailey, J.; Hough, J.H.

1981-01-01

A new simultaneous IR/optical high-speed photometer on the UK IR telescope has been used to study the recently discovered cataclysmic variable 1 E0643.0-1648. The light curve shows it to be a dwarf nova with a recurrence time scale of 15 days. Photometry obtained during the decline from an outburst showed slow flickering, with the IR and optical curves correlated with no delay. (author)

White Dwarfs in Cataclysmic Variables: An Update

Directory of Open Access Journals (Sweden)

E. M. Sion

2015-02-01

Full Text Available In this review, we summarize what is currently known about the surface temperatures of accreting white dwarfs in nonmagnetic and magnetic cataclysmic variables (CVs based upon synthetic spectral analyses of far ultraviolet data. We focus only on white dwarf surface temperatures, since in the area of chemical abundances, rotation rates, WD masses and accretion rates, relatively little has changed since our last review, pending the results of a large HST GO programinvolving 48 CVs of different CV types. The surface temperature of the white dwarf in SS Cygni is re-examined in the light of its revised distance. We also discuss new HST spectra of the recurrent nova T Pyxidis as it transitioned into quiescence following its April 2011 nova outburst.

Cataclysmic variables from a ROSAT/2MASS selection - I. Four new intermediate polars

NARCIS (Netherlands)

Gänsicke, B.T.; Marsh, T.R.; Edge, A.; Rodríguez-Gil, P.; Steeghs, D.; Araujo-Betancor, S.; Harlaftis, E.; Giannakis, O.; Pyrzas, S.; Morales-Rueda, L.; Aungwerojwit, A.

2005-01-01

We report the first results from a new search for cataclysmic variables (CVs) using a combined X-ray (ROSAT)/infrared (2MASS) target selection that discriminates against background active galactic nuclei. Identification spectra were obtained at the Isaac Newton Telescope for a total of 174 targets,

Cataclysmic Variables as Supernova Ia Progenitors

Directory of Open Access Journals (Sweden)

Stella Kafka

2012-06-01

Full Text Available Although the identification of the progenitors of type Ia supernovae (SNeIa remains controversial, it is generally accepted that they originate from binary star systems in which at least one component is a carbon-oxygen white dwarf (WD; those systems are grouped under the wide umbrella of cataclysmic variables. Current theories for SNeIa progenitors hold that, either via Roche lobe overflow of the companion or via a wind, the WD accumulates hydrogen or helium rich material which is then burned to C and O onto the WD’s surface. However, the specifics of this scenario are far from being understood or defined, allowing for a wealth of theories fighting for attention and a dearth of observations to support them. I discuss the latest attempts to identify and study those controversial SNeIa progenitors. I also introduce the most promising progenitor in hand and I present observational diagnostics that can reveal more members of the category.

Visualizing SPH Cataclysmic Variable Accretion Disk Simulations with Blender

Science.gov (United States)

Kent, Brian R.; Wood, Matthew A.

2015-01-01

We present innovative ways to use Blender, a 3D graphics package, to visualize smoothed particle hydrodynamics particle data of cataclysmic variable accretion disks. We focus on the methods of shape key data constructs to increasedata i/o and manipulation speed. The implementation of the methods outlined allow for compositing of the various visualization layers into a final animation. The viewing of the disk in 3D from different angles can allow for a visual analysisof the physical system and orbits. The techniques have a wide ranging set of applications in astronomical visualization,including both observation and theoretical data.

Cataclysmic variables in the SUPERBLINK proper motion survey

Energy Technology Data Exchange (ETDEWEB)

Skinner, Julie N.; Thorstensen, John R. [Department of Physics and Astronomy, 6127 Wilder Laboratory, Dartmouth College, Hanover, NH 03755-3528 (United States); Lépine, Sébastien, E-mail: jns@dartmouth.edu [Department of Physics and Astronomy, Georgia State University, 25 Park Place NE, Atlanta, GA 30303 (United States)

2014-12-01

We have discovered a new high proper motion cataclysmic variable (CV) in the SUPERBLINK proper motion survey, which is sensitive to stars with proper motions greater than 40 mas yr{sup −1}. This CV was selected for follow-up observations as part of a larger search for CVs selected based on proper motions and their near-UV−V and V−K{sub s} colors. We present spectroscopic observations from the 2.4 m Hiltner Telescope at MDM Observatory. The new CV's orbital period is near 96 minutes, its spectrum shows the double-peaked Balmer emission lines characteristic of quiescent dwarf novae, and its V magnitude is near 18.2. Additionally, we present a full list of known CVs in the SUPERBLINK catalog.

The Golden Age of Cataclysmic Variables and Related Objects - II Concluding Address

Directory of Open Access Journals (Sweden)

F. Giovannelli

2015-02-01

Full Text Available Before to conclude officially this workshop — far from me the idea to attempt some concluding remarks already dealt at the meeting with various burning by Joseph Patterson, Mariko Kato, Dmitry Bisikalo, and Rene Hudec —, I would like to comment few highlights coming out from our fruitful week of discussions about The Golden Age of Cataclysmic Variables and Related Objects - II, without any pretension of completeness.

Exploratory Spectroscopy of Magnetic Cataclysmic Variables Candidates and Other Variable Objects

Energy Technology Data Exchange (ETDEWEB)

Oliveira, A. S.; Palhares, M. S. [IP and D, Universidade do Vale do Paraíba, 12244-000, São José dos Campos, SP (Brazil); Rodrigues, C. V.; Cieslinski, D.; Jablonski, F. J. [Divisão de Astrofísica, Instituto Nacional de Pesquisas Espaciais, 12227-010, São José dos Campos, SP (Brazil); Silva, K. M. G. [Gemini Observatory, Casilla 603, La Serena (Chile); Almeida, L. A. [Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, 05508-900, São Paulo, SP (Brazil); Rodríguez-Ardila, A., E-mail: alexandre@univap.br [Laboratório Nacional de Astrofísica LNA/MCTI, 37504-364, Itajubá MG (Brazil)

2017-04-01

The increasing number of synoptic surveys made by small robotic telescopes, such as the photometric Catalina Real-Time Transient Survey (CRTS), provides a unique opportunity to discover variable sources and improves the statistical samples of such classes of objects. Our goal is the discovery of magnetic Cataclysmic Variables (mCVs). These are rare objects that probe interesting accretion scenarios controlled by the white-dwarf magnetic field. In particular, improved statistics of mCVs would help to address open questions on their formation and evolution. We performed an optical spectroscopy survey to search for signatures of magnetic accretion in 45 variable objects selected mostly from the CRTS. In this sample, we found 32 CVs, 22 being mCV candidates, 13 of which were previously unreported as such. If the proposed classifications are confirmed, it would represent an increase of 4% in the number of known polars and 12% in the number of known IPs. A fraction of our initial sample was classified as extragalactic sources or other types of variable stars by the inspection of the identification spectra. Despite the inherent complexity in identifying a source as an mCV, variability-based selection, followed by spectroscopic snapshot observations, has proved to be an efficient strategy for their discoveries, being a relatively inexpensive approach in terms of telescope time.

Astrometry with Hubble Space Telescope Fine Guidance Sensor 3: The Parallax of the Cataclysmic Variable RW Triangulum

Science.gov (United States)

McArthur, B. E.; Benedict, G. F.; Lee, J.; Lu, C.-L.; van Altena, W. F.; Deliyannis, C. P.; Girard, T.; Fredrick, L. W.; Nelan, E.; Duncombe, R. L.; Hemenway, P. D.; Jefferys, W. H.; Shelus, P. J.; Franz, O. G.; Wasserman, L. H.

1999-07-01

RW Triangulum (RW Tri) is a 13th magnitude nova-like cataclysmic variable star with an orbital period of 0.2319 days (5.56 hr). Infrared observations of RW Tri indicate that its secondary is most likely a late-K dwarf (Dhillon). Past analyses predicted a distance of 270 pc, derived from a blackbody fit to the spectrum of the central part of the disk (Rutten, van Paradijs, & Tinbergen). Recently completed Hubble Space Telescope Fine Guidance Sensor interferometric observations allow us to determine the first trigonometric parallax to RW Tri. This determination puts the distance of RW Tri at 341-31+38, one of the most distant objects with a direct parallax measurement. We compare our result with methods previously employed to estimate distances to cataclysmic variables.

Searching for nova shells around cataclysmic variables

Science.gov (United States)

Sahman, D. I.; Dhillon, V. S.; Knigge, C.; Marsh, T. R.

2015-08-01

We present the results of a search for nova shells around 101 cataclysmic variables (CVs), using H α images taken with the 4.2-m William Herschel Telescope (WHT) and the 2.5-m Isaac Newton Telescope Photometric H α Survey of the Northern Galactic Plane (IPHAS). Both telescopes are located on La Palma. We concentrated our WHT search on nova-like variables, whilst our IPHAS search covered all CVs in the IPHAS footprint. We found one shell out of the 24 nova-like variables we examined. The newly discovered shell is around V1315 Aql and has a radius of ˜2.5 arcmin, indicative of a nova eruption approximately 120 yr ago. This result is consistent with the idea that the high mass-transfer rate exhibited by nova-like variables is due to enhanced irradiation of the secondary by the hot white dwarf following a recent nova eruption. The implications of our observations for the lifetime of the nova-like variable phase are discussed. We also examined four asynchronous polars, but found no new shells around any of them, so we are unable to confirm that a recent nova eruption is the cause of the asynchronicity in the white dwarf spin. We find tentative evidence of a faint shell around the dwarf nova V1363 Cyg. In addition, we find evidence for a light echo around the nova V2275 Cyg, which erupted in 2001, indicative of an earlier nova eruption ˜300 yr ago, making V2275 Cyg a possible recurrent nova.

CATACLYSMIC VARIABLES FROM SDSS. VII. THE SEVENTH YEAR (2006)

International Nuclear Information System (INIS)

Szkody, Paula; Anderson, Scott F.; Hayden, Michael; Kronberg, Martin; McGurk, Rosalie; Riecken, Thomas; Schmidt, Gary D.; West, Andrew A.; Gaensicke, Boris T.; Gomez-Moran, Ada N.; Schwope, Axel D.; Schneider, Donald P.; Schreiber, Matthias R.

2009-01-01

Coordinates, magnitudes, and spectra are presented for 39 cataclysmic variables (CVs) found in Sloan Digital Sky Survey (SDSS) spectra that were primarily obtained in 2006. Of these, 13 were CVs identified prior to the SDSS spectra (AK Cnc, GY Cnc, GO Com, ST LMi, NY Ser, MR Ser, QW Ser, EU UMa, IY UMa, HS1340+1524, RXJ1610.1+0352, Boo 1, Leo 5). Follow-up spectroscopic observations of seven systems (including one from year 2005 and another from year 2004) were obtained, resulting in estimates of the orbital periods for three objects. The new CVs include two candidates for high inclination, eclipsing systems, four new polars, and three systems whose spectra clearly reveal atmospheric absorption lines from the underlying white dwarf.

The evolution of polar caps in magnetic cataclysmic variables

International Nuclear Information System (INIS)

Frank, J.; Chanmugam, G.

1986-01-01

A simple analysis of the evolution of the size of the magnetic polar cap in accreting white dwarfs is made on the basis of current theories of the secular evolution of magnetic cataclysmic variables. For white dwarfs with dipolar fields it is shown that the size of the polar cap in DQ Her binaries is larger than in AM Her binaries. The size of the former is, however, smaller than deduced from interpretation of their X-ray light curves, while that of the latter is in rough agreement. If the dwarf contains an aligned magnetic quadrupole the size of the polar caps of the DQ Her binaries is significantly increased. Magnetic field decay of the quadrupole moment in the older AM Her binaries implies that their fields are predominantly dipolar. (author)

SWSex Stars, Old Novae, and the Evolution of Cataclysmic Variables

Directory of Open Access Journals (Sweden)

L. Schmidtobreick

2015-02-01

Full Text Available The population of cataclysmic variables with orbital periods right above the period gap are dominated by systems with extremely high mass transfer rates, the so-called SW Sextantis stars. On the other hand, some old novae in this period range which are expected to show high mass transfer rate instead show photometric and/or spectroscopic resemblance to low mass transfer systems like dwarf novae. We discuss them as candidates for so-called hibernating systems, CVs that changed their mass transfer behaviour due to a previously experienced nova outburst. This paper is designed to provide input for further research and discussion as the results as such are still very preliminary.

White Dwarfs in Cataclysmic Variable Stars: Surface Temperatures and Evolution

Directory of Open Access Journals (Sweden)

Edward M. Sion

2012-06-01

Full Text Available A summary is presented of what is currently known about the surface temperatures of accreting white dwarfs (WDs detected in non-magnetic and magnetic cataclysmic variables (CVs based upon synthetic spectral analyses of far ultraviolet data. A special focus is placed on WD temperatures above and below the CV period gap as a function of the orbital period, Porb. The principal uncertainty of the temperatures for the CV WDs in the Teff - Porb distribution, besides the distance to the CV, is the mass of the WD. Only in eclipsing CV systems, an area of eclipsing binary studies, which was so central to Robert H. Koch’s career, is it possible to know CV WD masses with high precision.

Study of the eclipses of cataclysmic variables

International Nuclear Information System (INIS)

Zhang, E.H.

1986-01-01

The cataclysmic variables (CV's) are all close binary stars in which a secondary star fills its Roche lobe and transfers mass to its white dwarf companion. The transferred mass forms an accretion disk or ring, around the white dwarf. Reliable determinations of the masses of the two-component stars, the distributions of temperature and brightness across the disk, and other parameters, are necessary to understand both the CV's and the accretion processes, but they are extremely difficult to measure. The best way to obtain this data is to observe eclipsing CV's. The author developed a computer program to synthesize light curves of eclipsing CV's using the most realistic model built so far to analyze the eclipses of CV's. A statistical method was developed to perform a complete error analysis of the results of the numerical studies. High-speed, multi-color photometry of three eclipsing CV's - HT Cas, U Gem, and AC Cnc - was obtained. Using the program to analyze the observed light curves, the author derived, for each system, the orbital inclination, the sizes, masses and temperature of the two component stars, and the temperature distribution across the disk

The optical counterpart of IGR J00291+5934 in quiescence

Science.gov (United States)

D'Avanzo, P.; Campana, S.; Covino, S.; Israel, G. L.; Stella, L.; Andreuzzi, G.

2007-09-01

Aims:The recent (December 2004) discovery of the sixth accretion-powered millisecond X-ray pulsar IGR J00291+5934 provides a very good chance to deepen our knowledge of such systems. Although these systems are well studied at high energies, poor informations are available for their optical/NIR counterparts during quiescence. Up to now, only for SAX J1808.4-3658, the first discovered system of this type, we have a secure multiband detection of its optical counterpart in quiescence. Among the seven known system IGR J00291+5934 is the one that resembles SAX J1808.4-3658 more closely. Methods: With the Italian 3.6 m TNG telescope, we have performed deep optical and NIR photometry of the field of IGR J00291+5934 during quiescence in order to look for the presence of a variable counterpart. Results: We present here the first multiband (VRIJH) detection of the optical and NIR counterpart of IGR J00291+5934 in quiescence as well as a deep upper limit in the K-band. We obtain an optical light curve that shows variability consistent with a sinusoidal modulation at the known 2.46 h orbital period and present evidence for a strongly irradiated companion. Based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.

SPECTROSCOPY OF NEW AND POORLY KNOWN CATACLYSMIC VARIABLES IN THE KEPLER FIELD

International Nuclear Information System (INIS)

Howell, Steve B.; Still, Martin; Everett, Mark E.; Seebode, Sally A.; Szkody, Paula; Wood, Matt; Ramsay, Gavin; Cannizzo, John; Smale, Alan

2013-01-01

The NASA Kepler mission has been in science operation since 2009 May and is providing high precision, high cadence light curves of over 150,000 targets. Prior to launch, nine cataclysmic variables were known to lie within Kepler's field of view. We present spectroscopy for seven systems, four of which were newly discovered since launch. All of the stars presented herein have been observed by, or are currently being observed by, the Kepler space telescope. Three historic systems and one new candidate could not be detected at their sky position and two candidates are called into question as to their true identity.

Exploratory Spectroscopy of Magnetic Cataclysmic Variables Candidates and Other Variable Objects

Science.gov (United States)

Oliveira, A. S.; Rodrigues, C. V.; Cieslinski, D.; Jablonski, F. J.; Silva, K. M. G.; Almeida, L. A.; Rodríguez-Ardila, A.; Palhares, M. S.

2017-04-01

The increasing number of synoptic surveys made by small robotic telescopes, such as the photometric Catalina Real-Time Transient Survey (CRTS), provides a unique opportunity to discover variable sources and improves the statistical samples of such classes of objects. Our goal is the discovery of magnetic Cataclysmic Variables (mCVs). These are rare objects that probe interesting accretion scenarios controlled by the white-dwarf magnetic field. In particular, improved statistics of mCVs would help to address open questions on their formation and evolution. We performed an optical spectroscopy survey to search for signatures of magnetic accretion in 45 variable objects selected mostly from the CRTS. In this sample, we found 32 CVs, 22 being mCV candidates, 13 of which were previously unreported as such. If the proposed classifications are confirmed, it would represent an increase of 4% in the number of known polars and 12% in the number of known IPs. A fraction of our initial sample was classified as extragalactic sources or other types of variable stars by the inspection of the identification spectra. Despite the inherent complexity in identifying a source as an mCV, variability-based selection, followed by spectroscopic snapshot observations, has proved to be an efficient strategy for their discoveries, being a relatively inexpensive approach in terms of telescope time. Based on observations obtained at the Observatório do Pico dos Dias/LNA, and at the Southern Astrophysical Research (SOAR) telescope, which is a joint project of the Ministério da Ciência, Tecnologia, e Inovação (MCTI) da República Federativa do Brasil, the U.S. National Optical Astronomy Observatory (NOAO), the University of North Carolina at Chapel Hill (UNC), and Michigan State University (MSU).

SPECTROSCOPY OF NEW AND POORLY KNOWN CATACLYSMIC VARIABLES IN THE KEPLER FIELD

Energy Technology Data Exchange (ETDEWEB)

Howell, Steve B.; Still, Martin [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Everett, Mark E. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Seebode, Sally A. [San Mateo High School, San Mateo, CA 94401 (United States); Szkody, Paula [Astronomy Department, University of Washington, Seattle, WA 98195 (United States); Wood, Matt [Physics and Astronomy Department, Texas A and M University-Commerce, Commerce, TX 75429 (United States); Ramsay, Gavin [Armagh Observatory, College Hill, Armagh BT61 9DG (United Kingdom); Cannizzo, John [CRESST and Astroparticle Physics Laboratory, NASA/GSFC, Greenbelt, MD 20771 (United States); Smale, Alan [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2013-04-15

The NASA Kepler mission has been in science operation since 2009 May and is providing high precision, high cadence light curves of over 150,000 targets. Prior to launch, nine cataclysmic variables were known to lie within Kepler's field of view. We present spectroscopy for seven systems, four of which were newly discovered since launch. All of the stars presented herein have been observed by, or are currently being observed by, the Kepler space telescope. Three historic systems and one new candidate could not be detected at their sky position and two candidates are called into question as to their true identity.

Eclipses of cataclysmic variables. II. U Geminorum

International Nuclear Information System (INIS)

Zhang, E.H.; Robinson, E.L.

1987-01-01

U Gem is an eclipsing dwarf nova with an orbital period of 4 h 15 m. High-speed, multicolor photometric observations of U Gem in its quiescent state were obtained. A program was used that synthesizes the light curves of cataclysmic variables to derive the properties of U Gem from its eclipses. Using radial velocity curves published by Wade (1981) and by Stover (1981), it was found that i = 69.7 + or - 0.7 deg, M1 = 1.12 + or - 0.13 solar masses, and M2 = 0.53 + or - 0.06 solar mass. The radial temperature distribution across the accretion disk in U Gem shows that the disk is a hollow ring around the white dwarf with R(out) = 0.30 + or - 0.04 and R(in) = 0.12 + or - 0.05 a, where a is the separation of the two stars. The temperature of the ring is 4800 + or - 300 K. The model also reproduces the published infrared light curves and ultraviolet spectral distributions of U Gem. A mass transfer rate of 7.8 x 10 to the -10th solar mass/yr is derived. The structure of the ring around the white dwarf is consistent with the current theories of accretion disk instabilities in dwarf novae. 39 references

Investigations of a New Eclipsing Cataclysmic Variable HBHA 4705-03

Science.gov (United States)

Yakin, D. G.; Suleimanov, V. F.; Shimansky, V. V.; Vlasyuk, V. V.; Spiridonova, O. I.

2013-01-01

Results of photometric and spectroscopic investigations of the recently discovered eclipsing cataclysmic variable star HBHA 4705-03 are presented. The emission spectra of the system show broad hydrogen and helium emission lines. The bright spots with an approximately zero velocity components are found in the Doppler maps for the hydrogen and ionized helium lines. The disc structure is more prominent in the maps for the neutral helium lines. The masses of the components (MWD = 0.54 ± 0.10M⊙ and MRD = 0.45 ± 0.05 M⊙), and the orbit inclination (i = 71.°8 ± 0.°7) were estimated using the radial velocity light curve and the eclipse width. The modeling of the light curve allows us to evaluate the bright spot parameters and the mass accretion rate (M ≍ 2 ·1017 g s-1).

SPECTROSCOPIC ORBITAL PERIODS FOR 29 CATACLYSMIC VARIABLES FROM THE SLOAN DIGITAL SKY SURVEY

Energy Technology Data Exchange (ETDEWEB)

Thorstensen, John R.; Taylor, Cynthia J.; Peters, Christopher S.; Skinner, Julie N. [Department of Physics and Astronomy 6127 Wilder Laboratory, Dartmouth College Hanover, NH 03755-3528 (United States); Southworth, John [Astrophysics Group Keele University Staffordshire ST5 5BG (United Kingdom); Gänsicke, Boris T. [Department of Physics University of Warwick Coventry CV4 7AL (United Kingdom)

2015-04-15

We report follow-up spectroscopy of 29 cataclysmic variables from the Sloan Digital Sky Survey (SDSS), 22 of which were discovered by SDSS and seven of which are previously known systems that were recovered in SDSS. The periods for 16 of these objects were included in the tabulation by Gänsicke et al. While most of the systems have periods less than 2 hr, only one has a period in the 80–86 minutes “spike” found by Gänsicke et al., and 11 have periods longer than 3 hr, indicating that the present sample is skewed toward longer-period, higher-luminosity objects. Seven of the objects have spectra resembling dwarf novae, but have apparently never been observed in outburst, suggesting that many cataclysmics with relatively low variability amplitude remain to be discovered. Some of the objects are notable. SDSS J07568+0858 and SDSS J08129+1911 were previously known to have deep eclipses; in addition to spectroscopy, we use archival data from the Catalina Real Time Transient Survey to refine their periods. We give a parallax-based distance of 195 (+54, −39) pc for LV Cnc (SDSS J09197+0857), which at P{sub orb} = 81 m has the shortest orbital period in our sample. SDSS J08091+3814 shows both the spectroscopic phase offset and phase-dependent absorption found in SW Sextantis stars. The average spectra of SDSS J08055+0720 and SDSS J16191+1351 show contributions from K-type secondaries, and SDSS J080440+0239 shows a contribution from an early M star. We use these to constrain the distances. SDSS J09459+2922 has characteristics typical of a magnetic system. SDSS11324+6249 may be a novalike variable, and if so, its orbital period (99 minutes) is unusually short for that subclass.

X-Ray Emission of Cataclysmic Variables Observed by Integral

Czech Academy of Sciences Publication Activity Database

Gális, R.; Eckert, D.; Paltani, S.; Münz, F.; Kocka, Matúš

2009-01-01

Roč. 18, 3-4 (2009), s. 321-326 ISSN 1392-0049 Grant - others:ESA(XE) ESA- PECS project No. 98023; VEGA(SK) 2/0078/10 Institutional research plan: CEZ:AV0Z10030501 Keywords : binaries starss * cataclysmic * X-rays Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 1.032, year: 2009

The High Degree of Sequence Plasticity of the Arenavirus Noncoding Intergenic Region (IGR) Enables the Use of a Nonviral Universal Synthetic IGR To Attenuate Arenaviruses.

Science.gov (United States)

Iwasaki, Masaharu; Cubitt, Beatrice; Sullivan, Brian M; de la Torre, Juan C

2016-01-06

Hemorrhagic fever arenaviruses (HFAs) pose important public health problems in regions where they are endemic. Concerns about human-pathogenic arenaviruses are exacerbated because of the lack of FDA-licensed arenavirus vaccines and because current antiarenaviral therapy is limited to an off-label use of ribavirin that is only partially effective. We have recently shown that the noncoding intergenic region (IGR) present in each arenavirus genome segment, the S and L segments (S-IGR and L-IGR, respectively), plays important roles in the control of virus protein expression and that this knowledge could be harnessed for the development of live-attenuated vaccine strains to combat HFAs. In this study, we further investigated the sequence plasticity of the arenavirus IGR. We demonstrate that recombinants of the prototypic arenavirus lymphocytic choriomeningitis virus (rLCMVs), whose S-IGRs were replaced by the S-IGR of Lassa virus (LASV) or an entirely nonviral S-IGR-like sequence (Ssyn), are viable, indicating that the function of S-IGR tolerates a high degree of sequence plasticity. In addition, rLCMVs whose L-IGRs were replaced by Ssyn or S-IGRs of the very distantly related reptarenavirus Golden Gate virus (GGV) were viable and severely attenuated in vivo but able to elicit protective immunity against a lethal challenge with wild-type LCMV. Our findings indicate that replacement of L-IGR by a nonviral Ssyn could serve as a universal molecular determinant of arenavirus attenuation. Hemorrhagic fever arenaviruses (HFAs) cause high rates of morbidity and mortality and pose important public health problems in regions where they are endemic. Implementation of live-attenuated vaccines (LAVs) will represent a major step to combat HFAs. Here we document that the arenavirus noncoding intergenic region (IGR) has a high degree of plasticity compatible with virus viability. This observation led us to generate recombinant LCMVs containing nonviral synthetic IGRs. These r

VHE gamma-rays from radio pulsars and cataclysmic variables

International Nuclear Information System (INIS)

De Jager, O.C.; Brink, C.; Meintjies, P.J.; Nel, H.I.; North, A.R.; Raubenheimer, B.C.; Van der Walt, D.J.

1990-01-01

We present the results of observations (above 1 TeV) of radio pulsars and cataclysmic variables with the Potchefstroom air Cerenkov facility. We were able to confirm our previous detection of PSR 1509-58 and the final significance is 1.7x10 -5 . A DC enhancement at the 10 -3 significance level was seen from the L 4 Lagrange position in the PSR 1957+20 system. This result was confirmed by COS-B data. We were also able to detect the 5.4 ms pulsar PSR 1855+09 at a marginal significance level of 5%. However, the best and longest observation indicates non-uniformity at the 0.005 significance level. The TeV light curve resembles the radio light curve. The latter is also reminiscent of other millisecond pulsar observed above 1 TeV. The intermediate polar AEAQR (P = 33.08s) shows a period shift which is consistent with recent model predictions. However, the present significance of this results does not allow an unambiguous claim. (orig.)

Features of the mass transfer in magnetic cataclysmic variables with fast-rotating white dwarfs

Directory of Open Access Journals (Sweden)

Isakova Polina

2014-01-01

Full Text Available The flow structure in magnetic cataclysmic variables was investigated taking into account the effects of strong magnetic field and fast rotation of the white dwarf. We modeled the AE Aqr system as a unique object that has the rotation period of the white dwarf is about 1000 times shorter than the orbital period of the binary system. Observations show that in spite of fast rotation of the white dwarf some part of the stream from the inner Lagrange point comes into the Roche lobe region. We analyzed possible mechanisms preventing material to outflow from the system.

Follow-up Observations of SDSS and CRTS Candidate Cataclysmic Variables II

Science.gov (United States)

Szkody, Paula; Everett, Mark E.; Dai, Zhibin; Serna-Grey, Donald

2018-01-01

Spectra of 38 candidate or known cataclysmic variables are presented. Most are candidate dwarf novae or systems containing possible highly magnetic white dwarfs, while a few (KR Aur, LS Peg, V380 Oph, and V694 Mon) are previously known objects caught in unusual states. Individual spectra are used to confirm a dwarf nova nature or other classification while radial velocities of 15 systems provide orbital periods and velocity amplitudes that aid in determining the nature of the objects. Our results substantiate a polar nature for four objects, find an eclipsing SW Sex star below the period gap, another as a likely intermediate polar, as well as two dwarf novae with periods in the middle of the gap. Based on observations obtained with the Apache Point Observatory (APO) 3.5 m telescope, which is owned and operated by the Astrophysical Research Consortium (ARC).

Dynamics of Line-Driven Winds from Disks in Cataclysmic Variables. I. Solution Topology and Wind Geometry

OpenAIRE

Feldmeier, Achim; Shlosman, Isaac

1999-01-01

We analyze the dynamics of 2-D stationary, line-driven winds from accretion disks in cataclysmic variable stars. The driving force is that of line radiation pressure, in the formalism developed by Castor, Abbott & Klein for O stars. Our main assumption is that wind helical streamlines lie on straight cones. We find that the Euler equation for the disk wind has two eigenvalues, the mass loss rate and the flow tilt angle with the disk. Both are calculated self-consistently. The wind is characte...

A Study of the Optical Components of the Hard X-Ray Sources IGR J17544-2619 and IGR J21343+4738 by Using RTT-150 Observations

Science.gov (United States)

Nikolaeva, E. A.; Bikmaev, I. F.; Shimansky, V. V.; Sakhibullin, N. A.

2017-06-01

We investigate parameters of two high-mass X-ray binary systems IGR J17544-2619 and IGR J21343+4738 discovered by INTEGRAL space observatory by using optical data of Russian Turkish Telescope (RTT-150). Long-term optical observations of X-ray binary systems IGR J17544-2619 and IGR J21343+4738 were carried out in 2007-2015. Based on the RTT-150 data we estimated orbital periods of these systems. We have modeled the profiles of line HeI 6678 Å in spectra of studied optical stars and obtain the parameters of the star's atmosphere.

THE FAINT 'HEARTBEATS' OF IGR J17091-3624: AN EXCEPTIONAL BLACK HOLE CANDIDATE

Energy Technology Data Exchange (ETDEWEB)

Altamirano, D.; Van der Klis, M.; Wijnands, R.; Kalamkar, M. [Astronomical Institute, ' Anton Pannekoek' , University of Amsterdam, Science Park 904, 1098XH, Amsterdam (Netherlands); Belloni, T.; Stiele, H.; Motta, S.; Munoz-Darias, T. [INAF-Osservatorio Astronomico di Brera, Via E. Bianchi 46, I-23807 Merate (Italy); Linares, M. [Massachusetts Institute of Technology-Kavli Institute for Astrophysics and Space Research, Cambridge, MA 02139 (United States); Curran, P. A. [Laboratoire AIM, CEA DSM/IRFU/SAp, Centre de Saclay, F-91191 Gif-sur-Yvette (France); Casella, P. [School of Physics and Astronomy, University of Southampton, Southampton, Hampshire, SO17 1BJ (United Kingdom); Krimm, H., E-mail: d.altamirano@uva.nl [CRESST and NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

2011-12-15

We report on the first 180 days of Rossi X-Ray Timing Explorer observations of the outburst of the black hole candidate IGR J17091-3624. This source exhibits a broad variety of complex light curve patterns including periods of strong flares alternating with quiet intervals. Similar patterns in the X-ray light curves have been seen in the (up to now) unique black hole system GRS 1915+105. In the context of the variability classes defined by Belloni et al. for GRS 1915+105, we find that IGR J17091-3624 shows the {nu}, {rho}, {alpha}, {lambda}, {beta}, and {mu} classes as well as quiet periods which resemble the {chi} class, all occurring at 2-60 keV count rate levels which can be 10-50 times lower than observed in GRS 1915+105. The so-called {rho} class 'heartbeats' occur as fast as every few seconds and as slow as {approx}100 s, tracing a loop in the hardness-intensity diagram which resembles that previously seen in GRS 1915+105. However, while GRS 1915+105 traverses this loop clockwise, IGR J17091-3624 does so in the opposite sense. We briefly discuss our findings in the context of the models proposed for GRS 1915+105 and find that either all models requiring near Eddington luminosities for GRS 1915+105-like variability fail, or IGR J17091-3624 lies at a distance well in excess of 20 kpc, or it harbors one of the least massive black holes known (<3 M{sub Sun }).

Hydrodynamic simulations of accretion disks in cataclysmic variables

International Nuclear Information System (INIS)

Hirose, Masahito; Osaki, Yoji

1990-01-01

The tidal effects of secondary stars on accretion disks in cataclysmic variables are studied by two-dimensional hydrodynamical simulations. The time evolution of an accretion disk under a constant mass supply rate from the secondary is followed until it reaches a quasi-steady state. We have examined various cases of different mass ratios of binary systems. It is found that the accretion disk settles into a steady state of an elongated disk fixed in the rotating frame of the binary in a binary system with comparable masses of component stars. On the other hand, in the case of a low-mass secondary, the accretion disk develops a non-axisymmetric (eccentric) structure and finally settles into a periodically oscillating state in which a non-axisymmetric eccentric disk rotates in the opposite direction to the orbital motion of the binary in the rotating frame of the binary. The period of oscillation is a few percent longer than the orbital period of the binary, and it offers a natural explanation for the ''superhump'' periodicity of SU UMa stars. Our results thus confirm basically those of Whitehurst (1988, AAA 45.064.032) who discovered the tidal instability of an accretion disk in the case of a low-mass secondary. We then discuss the cause of the tidal instability. It is shown that the tidal instability of accretion disks is caused by a parametric resonance between particle orbits and an orbiting secondary star with a 1:3 period ratio. (author)

Follow up observations of SDSS and CRTS candidate cataclysmic variables

Energy Technology Data Exchange (ETDEWEB)

Szkody, Paula; Vasquez-Soltero, Stephanie [Department of Astronomy, University of Washington, P.O. Box 351580, Seattle, WA 98195 (United States); Everett, Mark E.; Silva, David R. [National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719 (United States); Howell, Steve B. [NASA Ames Research Center, Moffett Field, CA 94035 (United States); Landolt, Arlo U. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803 (United States); Bond, Howard E., E-mail: szkody@astro.washington.edu, E-mail: dsilva@noao.edu, E-mail: steve.b.howell@nasa.gov, E-mail: landolt@rouge.phys.lsu.edu, E-mail: heb11@psu.edu [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States)

2014-10-01

We present photometry and spectroscopy of 11 and 35 potential cataclysmic variables, respectively, from the Sloan Digital Sky Survey, the Catalina Real-Time Transient Survey, and vsnet alerts. The photometry results include quasi-periodic oscillations during the decline of V1363 Cyg, nightly accretion changes in the likely Polar (AM Herculis binary) SDSS J1344+20, eclipses in SDSS J2141+05 with an orbital period of 76 ± 2 minutes, and possible eclipses in SDSS J2158+09 at an orbital period near 100 minutes. Time-resolved spectra reveal short orbital periods near 80 minutes for SDSS J0206+20, 85 minutes for SDSS J1502+33, and near 100 minutes for CSS J0015+26, RXS J0150+37, SDSS J1132+62, SDSS J2154+15, and SDSS J2158+09. The prominent He II line and velocity amplitude of SDSS J2154+15 are consistent with a Polar nature for this object, while the absence of this line and a low velocity amplitude argue against this classification for RXS J0150+37. Single spectra of 10 objects were obtained near outburst and the rest near quiescence, confirming the dwarf novae nature of these objects.

Discovery of a New Classical Nova Shell Around a Nova-like Cataclysmic Variable

Science.gov (United States)

Guerrero, Martín A.; Sabin, Laurence; Tovmassian, Gagik; Santamaría, Edgar; Michel, Raul; Ramos-Larios, Gerardo; Alarie, Alexandre; Morisset, Christophe; Bermúdez Bustamante, Luis C.; González, Chantal P.; Wright, Nick J.

2018-04-01

The morphology and optical spectrum of IPHASX J210204.7+471015, a nebula classified as a possible planetary nebula are, however, strikingly similar to those of AT Cnc, a classical nova shell around a dwarf nova. To investigate its true nature, we have obtained high-resolution narrowband [O III] and [N II] images and deep optical spectra. The nebula shows an arc of [N II]-bright knots notably enriched in nitrogen, while an [O III]-bright bow shock is progressing throughout the ISM. Diagnostic line ratios indicate that shocks are associated with the arc and bow shock. The central star of this nebula has been identified by its photometric variability. Time-resolved photometric and spectroscopic data of this source reveal a period of 4.26 hr, which is attributed to a binary system. The optical spectrum is notably similar to that of RW Sex, a cataclysmic variable star (CV) of the UX UMa nova-like (NL) type. Based on these results, we propose that IPHASX J210204.7 + 471015 is a classical nova shell observed around a CV-NL system in quiescence.

The Faint "Heartbeats" of IGR J17091-3624: An Exceptional Black Hole Candidate

Science.gov (United States)

Altamirano, D.; Belloni, T.; Linares, M.; VanDerKlis, M.; Wunands, R.; Curran, P. A.; Kalamkar, M.; Stiele, H.; Motta, S.; Munoz-Darias, T.;

IDENTIFICATIONS OF FIVE INTEGRAL SOURCES VIA OPTICAL SPECTROSCOPY

International Nuclear Information System (INIS)

Butler, Suzanne C.; Tomsick, John A.; Chaty, Sylvain; Heras, Juan A. Zurita; Rodriguez, Jerome; Walter, Roland; Kaaret, Philip; Kalemci, Emrah; Oezbey, Mehtap

2009-01-01

The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) is discovering hundreds of new hard X-ray sources, many of which remain unidentified. We report on optical spectroscopy of five such sources for which X-ray observations at lower energies (∼0.5-10 keV) and higher angular resolutions than INTEGRAL have allowed for unique optical counterparts to be located. We find that INTEGRAL Gamma-Ray (IGR) J16426+6536 and IGR J22292+6647 are Type 1 Seyfert active galactic nuclei (with IGR J16426+6536 further classified as a Seyfert 1.5) which have redshifts of z = 0.323 and z = 0.113, respectively. IGR J18308-1232 is identified as a cataclysmic variable (CV), and we confirm a previous identification of IGR J19267+1325 as a magnetic CV. IGR J18214-1318 is identified as an obscured high-mass X-ray binary (HMXB), which are systems thought to have a compact object embedded in the stellar wind of a massive star. We combine Chandra fluxes with distances based on the optical observations to calculate X-ray luminosities of the HMXB and CVs, finding L 0.3-10keV = 5 x 10 36 erg s -1 for IGR J18214-1318, L 0.3-10keV = 1.3 x 10 32 erg s -1 for IGR J18308-1232, and L 0.3-10keV = 6.7 x 10 32 erg s -1 for IGR J19267+1325.

Theoretical, numerical and experimental study of accretion shocks dynamics in magnetic cataclysmic variables

International Nuclear Information System (INIS)

Busschaert, Clotilde

2013-01-01

Magnetic cataclysmic variables are interacting binary Systems containing a highly magnetized white dwarf which accretes material from a companion. Material is led along magnetic field lines and falls onto the magnetic pole(s) supersonically forming an accretion column. As the material hits the surface, a reverse shock is formed and the shocked region is structured by the cooling effect of radiation processes. This work is a multidisciplinary study of the dynamics of the accretion column. Firstly, a numerical study of the accretion column structure at the astrophysical scale is presented. The observational consequences are discussed. This approach is completed by experiments using radiative flows generated by powerful lasers. The relevance of such experiments is based on the establishment of scaling laws. News scaling laws in the frame of radiative ideal or resistive MHD are exposed. The results of the sizing and the interpretation of the POLAR experimental campaign of 2012 on LULI2000 installation are presented. (author) [fr

Period changes of cataclysmic variables below the period gap: V2051 Oph, OY Car and Z Cha

Science.gov (United States)

Pilarčík, L.; Wolf, M.; Zasche, P.; Vraštil, J.

2018-04-01

We present our results of a long-term monitoring of cataclysmic variable stars (CVs). About 40 new eclipses were measured for the three southern SU UMa-type eclipsing CVs: V2051 Oph, OY Car and Z Cha. Based on the current O - C diagrams we confirmed earlier findings that V2051 Oph and OY Car present cyclic changes of their orbital periods lasting 25 and 29 years, respectively. In case of Z Cha we propose the light-time effect caused probably by a presence of the third component orbiting the eclipsing CV with the period of 43.5 years. The minimal mass of this companion results about 15 MJup.

DISCOVERY OF A NOVA-LIKE CATACLYSMIC VARIABLE IN THE KEPLER MISSION FIELD

International Nuclear Information System (INIS)

Williams, Kurtis A.; De Martino, Domitilla; Silvotti, Roberto; Bruni, Ivan; Dufour, Patrick; Riecken, Thomas S.; Kronberg, Martin; Mukadam, Anjum; Handler, G.

2010-01-01

We announce the identification of a new cataclysmic variable (CV) star in the field of the Kepler Mission, KIC J192410.81+445934.9. This system was identified during a search for compact pulsators in the Kepler field. High-speed photometry reveals coherent large-amplitude variability with a period of 2.94 hr. Rapid, large-amplitude quasi-periodic variations are also detected on time scales of ∼1200 s and ∼650 s. Time-resolved spectroscopy covering one half photometric period shows shallow, broad Balmer and He I absorption lines with bright emission cores as well as strong He II and Bowen blend emission. Radial velocity variations are also observed in the Balmer and He I emission lines that are consistent with the photometric period. We therefore conclude that KIC J192410.81+445934.9 is a nova-like (NL) variable of the UX UMa class in or near the period gap, and it may belong to the rapidly growing subclass of SW Sex systems. Based on Two Micron All Sky Survey photometry and companion star models, we place a lower limit on the distance to the system of ∼500 pc. Due to limitations of our discovery data, additional observations including spectroscopy and polarimetry are needed to confirm the nature of this object. Such data will enable further understanding of the behavior of NL variables in the critical period range of 3-4 hr, where standard CV evolutionary theory finds major problems. The presence of this system in the Kepler Mission field of view also presents a unique opportunity to obtain a continuous photometric data stream of unparalleled length and precision on a CV system.

Machine learning from hard x-ray surveys: applications to magnetic cataclysmic variable studies

Science.gov (United States)

Scaringi, Simone

2009-11-01

Within this thesis are discussed two main topics of contemporary astrophysics. The first is that of machine learning algorithms for astronomy whilst the second is that of magnetic cataclysmic variables (mCVs). To begin, an overview is given of ISINA: INTEGRAL Scouce Identifiction Network Algorithm. This machine learning algorithm, using random forests, is applied to the IBIS/ISGRI data set in order to ease the production of unbiased future soft gamma-ray source catalogues. The feature extraction process on an initial candidate list is described together with feature merging. Three trainng and testing sets are created in order to deal with the diverse time-scales encountered when dealing with the gamma-ray sky: one dealing with faint persistent source recognition, one dealing with strong persistent sources and a final one dealing with transients. For the latter, a new transient detection technique is introduced and described: the transient matrix. Finally the performance of the network is assessed and discussed using the testing set and some illustrative source examples. ISINA is also compared to the more conventional approach of visual inspection. Next mCVs are discussed, and in particular the properties arising from a hard X-ray selected sample which has proven remarkably efficient in detecting intermediate polars and asynchronous polars, two of the rarest type of cataclysmic variables (CVs). This thesis focuses particularly on the link between hard X-ray properties and spin/orbital periods. To this end, a new sample of these objects is constructed by cross-corelating candidate sources detected in INTEGRAL/IBIS observations against catalogues of known CVs. Also included in the analysis are hard X-ray Observations from Swift/BAT and SUZAKU/HXD in order to make the study more complete. It is found that most hard X-ray detected mCVs have Pspin/Porb<0.1 above the period gap. In this respect, attention is given to the very low number of detected systems in any ban

Analysis of cataclysmic variable GSC02197-00886 evolution

Science.gov (United States)

Mitrofanova, A. A.; Borisov, N. V.; Shimansky, V. V.

2014-01-01

We present the spectral analysis of the physical state and evolution of the WZSge-type cataclysmic variable GSC02197-00886. The spectra of the system, covering the total orbital period at the time of the outburst on May 8, 2010, at the late relaxation stage, and in the quiescent state, were obtained at the SAO RAS 6-m BTA telescope in 2010-2012. From the absorption and emission HI, He I, and Fe II lines, we have determined the radial velocities for all the nights of observations and constructed the maps of Doppler tomography for the quiescent state. It was found that during the outburst the spectra of the object were formed in an optically thick accretion disk with an effective temperature of T eff ≈ 45 000 K and in a hotter boundary layer. During the relaxation of the system, the accretion disk gradually became optically thinner in the continuum and in the emission lines. In the quiescent state (July 2012), the continuous spectrum was dominated by the radiation of the cooling white dwarf with T eff = 18 000 K. The emission lines are formed on the surface of the cool star by the X-ray irradiation of the 1RXSJ213807.1+261958 source. We propose a method for determining the parameters of the white dwarf, based on the numerical modeling of the system spectra in the quiescent state and their comparison with the observed spectra. It is shown that the effective temperature of white dwarf has decreased by Δ T eff = 6000 K during the relaxation from August 2010 to July 2012. We have obtained a set of parameters for GSC02197-00886 and shown their good agreement with the average parameters of the W Z Sge-type systems, presented in the literature.

XMM-NEWTON AND OPTICAL OBSERVATIONS OF CATACLYSMIC VARIABLES FROM THE SLOAN DIGITAL SKY SURVEY

International Nuclear Information System (INIS)

Hilton, Eric J.; Szkody, Paula; Mukadam, Anjum; Henden, Arne; Dillon, William; Schmidt, Gary D.

2009-01-01

We report on XMM-Newton and optical results for six cataclysmic variables that were selected from Sloan Digital Sky Survey (SDSS) spectra because they showed strong He II emission lines, indicative of being candidates for containing white dwarfs with strong magnetic fields. While high X-ray background rates prevented optimum results, we are able to confirm SDSS J233325.92+152222.1 as an intermediate polar from its strong pulse signature at 21 minutes and its obscured hard X-ray spectrum. Ground-based circular polarization and photometric observations were also able to confirm SDSS J142256.31 - 022108.1 as a polar with a period near 4 hr. Photometry of SDSS J083751.00+383012.5 and SDSS J093214.82+495054.7 solidifies the orbital period of the former as 3.18 hr and confirms the latter as a high-inclination system with deep eclipses.

The primary role of the SW Sextantis stars in the evolution of cataclysmic variables

Science.gov (United States)

Torres, Manuel; Gaensicke, Boris; Rodriguez-Gil, Pablo; Long, Knox; Marsh, Tom; Steeghs, Danny; Munoz-Darias, Teodoro; Shahbaz, Tariq; Schmidtobreick, Linda; Schreiber, Matthias

2009-02-01

SW Sextantis stars are a relatively large group of cataclysmic variables (CVs) which plays a fundamental role in our understanding of CV structure and evolution. Very little is known about the properties of their accreting white dwarfs and their donor stars, as the stellar components are usually outshone by an extremely bright accretion flow. Consequently, a proper assesment of their evolutionary state is illusionary. We are monitoring the brightness of a number of SW Sex stars and request here Gemini/GMOS-N ToO time to obtain orbital phase-resolved spectroscopy if one of them enters a low state, since this is the only opportunity for studying the stellar components individually. These data will be used to accurately measure the binary parameters, white dwarf temperature, and distance to the system for a SW Sex star for the first time. The measured stellar masses and radii will especially be a precious input to the theory of compact binary evolution as a whole.

Unravelling the role of the SW Sextantis stars in the evolution of cataclysmic variables

Science.gov (United States)

Torres, Manuel; Steeghs, Danny; Gaensicke, Boris; Marsh, Tom; Rodriguez-Gil, Pablo; Schmidtobreick, Linda; Long, Knox; Schreiber, Matthias

2007-08-01

SW Sextantis stars are a relatively large group of cataclysmic variables (CVs) whose properties contradict all predictions made by the current CV evolution theories. Very little is known about the properties of their accreting white dwarfs and their donor stars, as the stellar components are usually outshone by an extremely bright accretion flow. Consequently, a proper assesment of their evolutionary state is illusionary. We are monitoring the brightness of a number of SW Sex stars and request here Gemini/GMOS-N ToO time to obtain orbital phase-resolved spectroscopy if one of them enters a low state, since this is the only opportunity for studying the stellar components individually. These data will be used to accurately measure the mass ratio of the system which, combined with the orbital inclination derived from modelling of either the disc eclipses in the high state or the ellipsoidal modulation in the low state, will eventually provide the first detailed system parameters for any SW Sex star.

PN G068.1+11.0: A young pre-cataclysmic variable with an extremely hot primary

Science.gov (United States)

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

2016-02-01

An analysis of spectroscopic and photometric data for the young pre-cataclysmic variable (PCV) PN G068.1+11.0, which passed through its common-envelope stage relatively recently, is presented. The spectroscopic and photometric data were obtained with the 6-m telescope and Zeiss-1000 telescope of the Special Astrophysical Observatory. The light curves show sinusoidal brightness variations with the orbital-period time scale and brightness-variation amplitudes of Δ m = 1. m41, 1. m62, and 1. m57 in the B, V, and R bands, respectively. The system's spectrum exhibits weak HI (H β-H δ) andHeII λλ4541, 4686, 5411 Å absorption lines during the phases of minimum brightness, as well as HI, HeII, CIII, CIV, NIII, and OII emission lines whose intensity variations are synchronized with variations of the integrated brightness of the system. The emission-line formation in the spectra can be fully explained by the effects of fluorescence of the ultraviolet light from the primary at the surface of the cool star. All the characteristics of the optical light of PN G068.1+11.0 confirm that it is a young PCV containing sdO subdwarf. The radial velocities were measured from a blend of lines of moderately light elements, CIII+NIII λ4640 Å, which is formed at the surface of the secondary due to reflection effects. The ephemeris of the system has been improved through a joint analysis of the radial-velocity curves and light curves of pre-cataclysmic variable, using modelling of the reflection effects. The fundamental parameters of PN G068.1+11.0 have been determined using two evolutionary tracks for planetary-nebula nuclei of different masses (0.7 M ⊙and 0.78 M ⊙). The model spectra for the system and a comparison with the observations demonstrate the possibility of refining the components' effective temperatures if the quality of the spectra used is improved.

IGR J17329-2731: The birth of a symbiotic X-ray binary

Science.gov (United States)

Bozzo, E.; Bahramian, A.; Ferrigno, C.; Sanna, A.; Strader, J.; Lewis, F.; Russell, D. M.; di Salvo, T.; Burderi, L.; Riggio, A.; Papitto, A.; Gandhi, P.; Romano, P.

2018-05-01

We report on the results of the multiwavelength campaign carried out after the discovery of the INTEGRAL transient IGR J17329-2731. The optical data collected with the SOAR telescope allowed us to identify the donor star in this system as a late M giant at a distance of 2.7-1.2+3.4 kpc. The data collected quasi-simultaneously with XMM-Newton and NuSTAR showed the presence of a modulation with a period of 6680 ± 3 s in the X-ray light curves of the source. This unveils that the compact object hosted in this system is a slowly rotating neutron star. The broadband X-ray spectrum showed the presence of a strong absorption (≫1023 cm-2) and prominent emission lines at 6.4 keV, and 7.1 keV. These features are usually found in wind-fed systems, in which the emission lines result from the fluorescence of the X-rays from the accreting compact object on the surrounding stellar wind. The presence of a strong absorption line around 21 keV in the spectrum suggests a cyclotron origin, thus allowing us to estimate the neutron star magnetic field as 2.4 × 1012 G. All evidencethus suggests IGR J17329-2731 is a symbiotic X-ray binary. As no X-ray emission was ever observed from the location of IGR J17329-2731 by INTEGRAL (or other X-ray facilities) during the past 15 yr in orbit and considering that symbiotic X-ray binaries are known to be variable but persistent X-ray sources, we concluded that INTEGRAL caught the first detectable X-ray emission from IGR J17329-2731 when the source shined as a symbiotic X-ray binary. The Swift XRT monitoring performed up to 3 months after the discovery of the source, showed that it maintained a relatively stable X-ray flux and spectral properties.

CATACLYSMIC VARIABLES FROM THE SLOAN DIGITAL SKY SURVEY. VIII. THE FINAL YEAR (2007–2008)

International Nuclear Information System (INIS)

Szkody, Paula; Anderson, Scott F.; Brooks, Keira; Kronberg, Martin; Riecken, Thomas; Gänsicke, Boris T.; Ross, Nicholas P.; Schmidt, Gary D.; Schneider, Donald P.; Agüeros, Marcel A.; Gomez-Moran, Ada N.; Schwope, Axel D.; Knapp, Gillian R.; Schreiber, Matthias R.

2011-01-01

This paper completes the series of cataclysmic variables (CVs) identified from the Sloan Digital Sky Survey (SDSS) I/II. The coordinates, magnitudes, and spectra of 33 CVs are presented. Among the 33 are eight systems known prior to SDSS (CT Ser, DO Leo, HK Leo, IR Com, V849 Her, V405 Peg, PG1230+226, and HS0943+1404), as well as nine objects recently found through various photometric surveys. Among the systems identified since the SDSS are two polar candidates, two intermediate polar candidates, and one candidate for containing a pulsating white dwarf. Our follow-up data have confirmed a polar candidate from Paper VII and determined tentative periods for three of the newly identified CVs. A complete summary table of the 285 CVs with spectra from SDSS I/II is presented as well as a link to an online table of all known CVs from both photometry and spectroscopy that will continue to be updated as future data appear.

Unravelling the role of SW Sextantis stars in the evolution of cataclysmic variables

Science.gov (United States)

Araujo-Betancor, Sofia; Gansicke, Boris; Long, Knox; Rodriguez-Gil, Pablo

2005-08-01

SW Sextantis stars are a relatively large group of cataclysmic variables whose properties contradict all predictions made by the current CV evolution theories. Very little is known about the properties of their accreting white dwarfs and their donor stars, as the stellar components are usually outshone by an extremely bright accretion flow. Consequently, a proper assessment of their evolutionary state is illusionary. There is one particular behavior of the SW Sex stars that can allow us to overcome this problem: SW Sex stars exhibit low states during which accretion onto the white dwarf decreases or shuts off completely. Only during this rare occasions we can directly observe the white dwarf and the donor star in these systems, and measurements of the white dwarf temperature, spectral type of the donor, mass and distance to the system can be carried out. With this aim in mind, we have set up a long-term monitoring of a group of five SW Sex stars using the 1.3 m telescope at CTIO. Here we propose to activate follow-up TOOs to obtain optical spectra of the low states to accurately determine the fundamental properties of these systems.

Analiza igre branilcev v conski obrambi 5:1 pri rokometu

OpenAIRE

Kozole, Rok

2017-01-01

V diplomski nalogi je predstavljena analiza igre branilcev v conski obrambi 5:1 pri rokometu. Obrambna formacija 5:1 je po obrambi 6:0 druga najpogosteje uporabljena obrambna formacija, katere se poslužujejo tako ekipe iz vrhunskega rokometa kot tudi ekipe, ki tekmujejo v ligah nižje kakovosti. V skladu s hitrim razvojem rokometne igre se je razvijala tudi obramba 5:1. Obrambna formacija 5:1 se pri mlajših rokometaših uporablja tudi kot prehodna obramba oz. temelj za prehod iz bolj globokih (...

Izrada 2D video igre za iOS platformu

OpenAIRE

Kampuš, Dominik

2016-01-01

Tema ovog završnog rada temelji se na izradi 2D video igre za iOS mobilni uređaj te njezinoj demonstraciji na istom. Kroz rad su opisane sve bitne funkcije GameSalad Creator-a koje su potrebne kod izrade igre bazirane na 2 dimenzije. Također se prolazi kroz iOS operativni sustav, što je on i kako se razvijao. Spominje se i tema koja govori općenito o igrama na mobilnim uređajima. U završnom dijelu rada prikazan je postupak izrade, koje funkcije programa se točno koriste i kako se igra može te...

VizieR Online Data Catalog: Faint cataclysmic variables from SDSS (Woudt+, 2012)

Science.gov (United States)

Woudt, P. A.; Warner, B.; de Bude, D.; Macfarlane, S.; Schurch, M. P. E.; Zietsman, E.

2013-01-01

We present high-speed photometric observations of 20 faint cataclysmic variables (CVs) selected from the Sloan Digital Sky Survey (SDSS) and Catalina catalogues. Measurements are given of 15 new directly measured orbital periods, including four eclipsing dwarf novae (SDSS 0904+03, CSS 0826-00, CSS 1404-10 and CSS 1626-12), two new polars (CSS 0810+00 and CSS 1503-22) and two dwarf novae with superhumps in quiescence (CSS 0322+02 and CSS 0826-00). Whilst most of the dwarf novae presented here have periods below 2h, SDSS 0805+07 and SSS 0617-36 have relatively long orbital periods of 5.489 and 3.440h, respectively. The double-humped orbital modulations observed in SSS 0221-26, CSS 0345-01, CSS 1300+11 and CSS 1443-17 are typical of low-mass transfer rate dwarf novae. The white dwarf primary of SDSS 0919+08 is confirmed to have non-radial oscillations, and quasi-periodic oscillations were observed in the short-period dwarf nova CSS 1028-08 during outburst. We further report the detection of a new nova-like variable (SDSS 1519+06). The frequency distribution of orbital periods of CVs in the Catalina Real-time Transient Survey (CRTS) has a high peak near ~80min orbital period, independently confirming that found by Gansicke et al. (2009MNRAS.397.2170G) from SDSS sources. We also observe a marked correlation between the median in the orbital period distribution and the outburst class, in the sense that dwarf novae with a single observed outburst (over the 5-year baseline of the CRTS coverage) occur predominantly at shortest orbital period. (2 data files).

NON-THERMAL EMISSION FROM CATACLYSMIC VARIABLES: IMPLICATIONS ON ASTROPARTICLE PHYSICS

Directory of Open Access Journals (Sweden)

Vojtech Šimon

2013-12-01

Full Text Available We review the lines of evidence that some cataclysmic variables (CVs are the sources of non-thermal radiation. It was really observed in some dwarf novae in outburst, a novalike CV in the high state, an intermediate polar, polars, and classical novae (CNe during outburst. The detection of this radiation suggests the presence of highly energetic particles in these CVs. The conditions for the observability of this emission depend on the state of activity, and the system parameters. We review the processes and conditions that lead to the production of this radiation in various spectral bands, from gamma-rays including TeV emission to radio. Synchrotron and cyclotron emissions suggest the presence of strong magnetic fields in CV. In some CVs, e.g. during some dwarf nova outbursts, the magnetic field generated in the accretion disk leads to the synchrotron jets radiating in radio. The propeller effect or a shock in the case of the magnetized white dwarf (WD can lead to a strong acceleration of the particles that produce gamma-ray emission via pi0 decay; even Cherenkov radiation is possible. In addition, a gamma-ray production via pi0 decay was observed in the ejecta of an outburst of a symbiotic CN. Nuclear reactions during thermonuclear runaway in the outer layer of the WD undergoing CN outburst lead to the production of radioactive isotopes; their decay is the source of gamma-ray emission. The production of accelerated particles in CVs often has episodic character with a very small duty cycle; this makes their detection and establishing the relation of the behavior in various bands difficult.

The origin of the infrared light of cataclysmic variable stars

International Nuclear Information System (INIS)

Berriman, G.; Szkody, P.; Capps, R.W.

1985-01-01

This paper presents a model-independent overview of the origin of the near infrared (1-2 μm) light of a sample of 28 cataclysmic binary stars, largely dwarf novae in quiescence. The infrared light comes from the red dwarf that supplies matter to the white dwarf companion and the accretion disc around the white dwarf. The complex nature of the disc prevents near-infrared photometry from being a good probe of the red dwarfs, even in those systems where they are seen in the visual. All that can be found reliably is an upper limit to the proportion light that the red dwarfs supply, and consequently lower limits to the distances to the systems. The infrared light of the discs comes from opaque material and from the optically thin gas that gives rise to the visual and UV emission lines. (author)

PG 1316+678: A young pre-cataclysmic binary with weak reflection effects

Science.gov (United States)

Shimansky, V. V.; Borisov, N. V.; Bikmaev, I. F.; Sakhibullin, N. A.; Shimanskaya, N. N.; Spiridonova, O. I.; Irtuganov, E. N.

2013-03-01

The PG 1316+678 star is classified as a pre-cataclysmic binary, as is evidenced by its photometric and spectroscopic observations. Its orbital period is determined to be P orb = 3.3803d, which coincides with the photometric period. The intensities of the emission HI and HeI lines are shown to vary synchronously with the brightness of the object (Δ m V = 0.065 m , Δ m R = 0.08 m ). These variations arise as the UV radiation from the DAO white dwarf is reflected from the surface of the cold companion. The parameters of the binary are estimated and the time of its evolution after the common-envelope phase is determined to be t ≈ 240 000 years. Thus, PG 1316+678 is a young pre-cataclysmic NN Ser variable with the smallest known photometric reflection effect.

Cataclysmic Variables and Active Binary Stars in Omega Centauri

Science.gov (United States)

Arias, T.; Brochmann, M.; Dorfman, J. L.; White, M. V.; Cool, A. M.

2004-12-01

We report findings from our ongoing research on the globular cluster Omega Centauri (NGC 5139) using a 3x3 mosaic of Wide Field Camera pointings with the HST Advanced Camera for Surveys (ACS). The data consist of F435W (B435), F625W (R625), and F658N (Hα ) images and cover roughly 10x10 arcminutes, out to beyond the cluster's half-mass radius. Our current work is a search for cataclysmic variables (CVs) and active binaries (ABs) (e.g., RS CVn and BY Dra stars) as counterparts to X-ray point sources previously detected with Chandra. The ACS field encompasses 109 of the Chandra sources, 20-50 of which are likely to be cluster members according to our statistical estimates (the rest being primarily active galaxies). Using DAOPHOT to obtain photometry in 20x20 arcsecond patches surrounding each X-ray source, we are constructing color-magnitude diagrams to search for stars with Hα -R625 and/or B435-R625 colors indicative of CVs or ABs in ˜ 1 arcsecond Chandra error circles. With roughly half of the patches analyzed, several AB candidates and only a small number of CV candidates have emerged. Our tentative conclusion is that CVs may be significantly rarer in Omega Cen than in 47 Tuc, in contrast to the comparable numbers ( ˜100) predicted for these two clusters from tidal capture theory (Di Stefano and Rappaport 1994). Alternatively, the CVs could be strongly concentrated toward the cluster center, and thus not yet appear in our sample. To date, most of the patches we have analyzed are 3-4 arcminutes from the cluster center and thus are outside the cluster core (radius 2.6 arcminutes). Our continuing work should soon enable us to resolve this question. This work is supported by NASA grant GO-9442 from the Space Telescope Science Institute.

Non-radial oscillations of rotating stars and their relevance to the short-period oscillations of cataclysmic variables

International Nuclear Information System (INIS)

Papaloizou, J.; Pringle, J.E.

1978-01-01

The usual hypothesis, that the short-period coherent oscillations seen in cataclysmic variables are attributable to g modes in a slowly rotating white dwarf, is considered. It is shown that this hypothesis is untenable for three main reasons: (i) the observed periods are too short for reasonable white dwarf models, (ii) the observed variability of the oscillations is too rapid and (iii) the expected rotation of the white dwarf, due to accretion, invalidates the slow rotation assumption on which standard g-mode theory is based. The low-frequency spectrum of a rotating pulsating star is investigated taking the effects of rotation fully into account. In this case there are two sets of low-frequency modes, the g modes, and modes similar to Rossby waves in the Earth's atmosphere and oceans, which are designated r modes. Typical periods for such modes are 1/m times the rotation period of the white dwarfs outer layers (m is the aximuthal wavenumber). It is concluded that non-radial oscillations of rotating white dwarfs can account for the properties of the oscillations seen in dwarf novae. Application of these results to other systems is also discussed. (author)

Swift follow-up of the newly discovered burster millisecond pulsar IGR J17511-3057

DEFF Research Database (Denmark)

Bozzo, E.; Ferrigno, C.; Kuulkers, E.

2009-01-01

Following the discovery of the new hard X-ray transient IGR J17511-3057 by INTEGRAL (Atel #2196) and its classification as a millisecond pulsar by RXTE (Atel #2197), a Swift ToO was performed. Swift/XRT observed IGR J17511-3057 on 2009-09-13 at 19:53:31 for a total exposure time of 4 ks. The first...

Optical identification of IGR J19140+0951

NARCIS (Netherlands)

Zand, J.J.M. in't; Jonker, P.G.; Nelemans, G.A.; Steeghs, D.; O'Brien, K.

2006-01-01

IGR J19140+0951 was discovered by INTEGRAL in 2003 in the 4-100 keV band. Observations with INTEGRAL and RXTE provide a tentative identification as a high-mass X-ray binary (HMXB) with a neutron star as accretor. However, an optical counterpart was thus far not established, nor was the presence of a

EVOLUTION OF CATACLYSMIC VARIABLES AND RELATED BINARIES CONTAINING A WHITE DWARF

International Nuclear Information System (INIS)

Kalomeni, B.; Rappaport, S.; Molnar, M.; Nelson, L.; Quintin, J.; Yakut, K.

2016-01-01

We present a binary evolution study of cataclysmic variables (CVs) and related systems with white dwarf (WD) accretors, including for example, AM CVn systems, classical novae, supersoft X-ray sources (SXSs), and systems with giant donor stars. Our approach intentionally avoids the complications associated with population synthesis algorithms, thereby allowing us to present the first truly comprehensive exploration of all of the subsequent binary evolution pathways that zero-age CVs might follow (assuming fully non-conservative, Roche-lobe overflow onto an accreting WD) using the sophisticated binary stellar evolution code MESA. The grid consists of 56,000 initial models, including 14 WD accretor masses, 43 donor-star masses (0.1–4.7 M ⊙ ), and 100 orbital periods. We explore evolution tracks in the orbital period and donor-mass ( P orb – M don ) plane in terms of evolution dwell times, masses of the WD accretor, accretion rate, and chemical composition of the center and surface of the donor star. We report on the differences among the standard CV tracks, those with giant donor stars, and ultrashort period systems. We show where in parameter space one can expect to find SXSs, present a diagnostic to distinguish among different evolutionary paths to forming AM CVn binaries, quantify how the minimum orbital period in CVs depends on the chemical composition of the donor star, and update the P orb ( M wd ) relation for binaries containing WDs whose progenitors lost their envelopes via stable Roche-lobe overflow. Finally, we indicate where in the P orb – M don the accretion disks will tend to be stable against the thermal-viscous instability, and where gravitational radiation signatures may be found with LISA.

THE PECULIAR EVOLUTIONARY HISTORY OF IGR J17480-2446 IN TERZAN 5

International Nuclear Information System (INIS)

Patruno, Alessandro; Alpar, M. Ali; Van der Klis, Michiel; Van den Heuvel, Ed P. J.

2012-01-01

The low-mass X-ray binary (LMXB) IGR J17480-2446 in the globular cluster Terzan 5 harbors an 11 Hz accreting pulsar. This is the first object discovered in a globular cluster with a pulsar spinning at such low rate. The accreting pulsar is anomalous because its characteristics are very different from the other five known slow accreting pulsars in galactic LMXBs. Many features of the 11 Hz pulsar are instead very similar to those of accreting millisecond pulsars, spinning at frequencies >100 Hz. Understanding this anomaly is valuable because IGR J17480-2446 could be the only accreting pulsar discovered so far which is in the process of becoming an accreting millisecond pulsar. We first verify that the neutron star (NS) in IGR J17480-2446 is indeed spinning up by carefully analyzing X-ray data with coherent timing techniques that account for the presence of timing noise. We then study the present Roche lobe overflow epoch and the two previous spin-down epochs dominated by magneto-dipole radiation and stellar wind accretion. We find that IGR J17480-2446 is very likely a mildly recycled pulsar and suggest that it has started a spin-up phase in an exceptionally recent time, which has lasted less than a few 10 7 yr. We also find that the total age of the binary is surprisingly low (∼ 8 yr) when considering typical parameters for the newborn NS and propose different scenarios to explain this anomaly.

The Peculiar Evolutionary History of IGR J17480-2446 in Terzan 5

Science.gov (United States)

Patruno, Alessandro; Alpar, M. Ali; van der Klis, Michiel; van den Heuvel, Ed P. J.

2012-06-01

The low-mass X-ray binary (LMXB) IGR J17480-2446 in the globular cluster Terzan 5 harbors an 11 Hz accreting pulsar. This is the first object discovered in a globular cluster with a pulsar spinning at such low rate. The accreting pulsar is anomalous because its characteristics are very different from the other five known slow accreting pulsars in galactic LMXBs. Many features of the 11 Hz pulsar are instead very similar to those of accreting millisecond pulsars, spinning at frequencies >100 Hz. Understanding this anomaly is valuable because IGR J17480-2446 could be the only accreting pulsar discovered so far which is in the process of becoming an accreting millisecond pulsar. We first verify that the neutron star (NS) in IGR J17480-2446 is indeed spinning up by carefully analyzing X-ray data with coherent timing techniques that account for the presence of timing noise. We then study the present Roche lobe overflow epoch and the two previous spin-down epochs dominated by magneto-dipole radiation and stellar wind accretion. We find that IGR J17480-2446 is very likely a mildly recycled pulsar and suggest that it has started a spin-up phase in an exceptionally recent time, which has lasted less than a few 107 yr. We also find that the total age of the binary is surprisingly low (lsim 108 yr) when considering typical parameters for the newborn NS and propose different scenarios to explain this anomaly.

Optical identification of IGR J19140+0951

NARCIS (Netherlands)

in 't Zand, J.J.M.; Jonker, P.G.; Nelemans, G.; Steeghs, D.; O'Brien, K.

2006-01-01

IGR J19140+0951 was discovered by INTEGRAL in 2003 in the 4–100 keV band. Observations with INTEGRAL and RXTE provide a tentative identification as a high-mass X-ray binary (HMXB) with a neutron star as accretor. However, an optical counterpart was thus far not established, nor was the presence of a

EVOLUTION OF CATACLYSMIC VARIABLES AND RELATED BINARIES CONTAINING A WHITE DWARF

Energy Technology Data Exchange (ETDEWEB)

Kalomeni, B.; Rappaport, S.; Molnar, M. [Department of Physics, and Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Nelson, L. [Department of Physics, Bishop’s University, 2600 College St., Sherbrooke, Quebec, QC J1M 1Z7 (Canada); Quintin, J. [Department of Physics, McGill University, Montréal, QC H3A 2T8 (Canada); Yakut, K., E-mail: kalomeni@mit.edu, E-mail: sar@mit.edu, E-mail: momchil.molnar@gmail.com, E-mail: belinda.kalomeni@ege.edu.tr, E-mail: kadri.yakut@ege.edu.tr, E-mail: lnelson@ubishops.ca, E-mail: jquintin@physics.mcgill.ca [Department of Astronomy and Space Sciences, Ege University, 35100, İzmir (Turkey)

2016-12-10

We present a binary evolution study of cataclysmic variables (CVs) and related systems with white dwarf (WD) accretors, including for example, AM CVn systems, classical novae, supersoft X-ray sources (SXSs), and systems with giant donor stars. Our approach intentionally avoids the complications associated with population synthesis algorithms, thereby allowing us to present the first truly comprehensive exploration of all of the subsequent binary evolution pathways that zero-age CVs might follow (assuming fully non-conservative, Roche-lobe overflow onto an accreting WD) using the sophisticated binary stellar evolution code MESA. The grid consists of 56,000 initial models, including 14 WD accretor masses, 43 donor-star masses (0.1–4.7 M {sub ⊙}), and 100 orbital periods. We explore evolution tracks in the orbital period and donor-mass ( P {sub orb}– M {sub don}) plane in terms of evolution dwell times, masses of the WD accretor, accretion rate, and chemical composition of the center and surface of the donor star. We report on the differences among the standard CV tracks, those with giant donor stars, and ultrashort period systems. We show where in parameter space one can expect to find SXSs, present a diagnostic to distinguish among different evolutionary paths to forming AM CVn binaries, quantify how the minimum orbital period in CVs depends on the chemical composition of the donor star, and update the P {sub orb}( M {sub wd}) relation for binaries containing WDs whose progenitors lost their envelopes via stable Roche-lobe overflow. Finally, we indicate where in the P {sub orb}– M {sub don} the accretion disks will tend to be stable against the thermal-viscous instability, and where gravitational radiation signatures may be found with LISA.

Trauma-Informed Guilt Reduction (TrIGR) Intervention

Science.gov (United States)

2017-10-01

and maintenance of posttraumatic distress and a range of adverse outcomes, including posttraumatic stress disorder (PTSD), depression and suicidality ...posttraumatic distress and a range of adverse outcomes, including posttraumatic stress disorder (PTSD), depression and suicidality , and alcohol/substance use...PTSD symptoms, and depression with medium to large effect sizes. The overall objective of this study is to examine the efficacy of TrIGR in

Modelling the flaring activity of the high-z, hard X-ray-selected blazar IGR J22517+2217: Flaring activity of IGR J22517+2217

International Nuclear Information System (INIS)

Lanzuisi, G.; De Rosa, A.; Ghisellini, G.; Panessa, F.

2012-01-01

We present new Suzaku and Fermi data and re-analysed archival hard X-ray data from the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) and Swift–Burst Alert Telescope (BAT) surveys to investigate the physical properties of the luminous, high-redshift, hard X-ray-selected blazar IGR J22517+2217, through the modelling of its broad-band spectral energy distribution (SED) in two different activity states. Through analysis of new Suzaku data and flux-selected data from archival hard X-ray observations, we build the source SED in two different states, one for the newly discovered flare that occurred in 2005 and one for the following quiescent period. Both SEDs are strongly dominated by the high-energy hump peaked at 10 20 –10 22 Hz, which is at least two orders of magnitude higher than the low-energy (synchrotron) one at 10 11 –10 14 Hz and varies by a factor of 10 between the two states. In both states the high-energy hump is modelled as inverse Compton emission between relativistic electrons and seed photons produced externally to the jet, while the synchrotron self-Compton component is found to be negligible. In our model the observed variability can be accounted for by a variation of the total number of emitting electrons and by a dissipation region radius changing from inside to outside the broad-line region as the luminosity increases. In its flaring activity, IGR J22517+2217 is revealed as one of the most powerful jets among the population of extreme, hard X-ray-selected, high-redshift blazars observed so far.

INTEGRAL sees IGR J17544-2619 active again

DEFF Research Database (Denmark)

Chenevez, Jérôme; Kuulkers, Erik; Brandt, Søren

2010-01-01

INTEGRAL Galactic bulge monitoring observations (see, e.g., ATels #438 and #1266) between UT 29 Aug 2010 22:54 and 30 Aug 2010 02:35 revealed X-ray flaring from the Supergiant Fast X-ray Transient (SFXT) IGR J17544-2619. Its last activity was reported about 180 days ago, in March 2010 (ATel #2463...

FIZIOLOGIJA KOŠARKAŠKE IGRE

OpenAIRE

Matković, Branka; Matković, Bojan; Knjaz, Damir

2005-01-01

Suvremenu košarkašku igru karakterizira visoki intenzitet aktivnosti kroz praktički svih četrdeset minuta njenog trajanja, zahtijeva od igrača/ica široku paletu osnovnih i specifičnih funkcionalnih i motoričkih sposobnosti. Gotovo je nemoguće izolirati neku koja u određenoj mjeri ne sudjeluju u uspjehu u igri. Ovaj rad daje pregled fiziološke pozadine košarkaške igre te analizu kretanja tijekom utakmice. Nadalje daje pregled aerobnih, anaerobnih i motoričkih sposobnosti košarkaša i košarkašic...

Accretion torques due to three-dimensional channelled flows in magnetic cataclysmic variables

International Nuclear Information System (INIS)

Campbell, C.G.

1986-01-01

Angular momentum transfer due to three-dimensional magnetically channelled accretion flows in cataclysmic binaries is considered. The white dwarf experiences a torque due to the twist in that part of its magnetic field which interacts with the accretion stream. The channelling process can also enhance angular momentum exchange between the stream and the orbit by increasing the gravitational torques. The components of the accretion torque are calculated for an arbitrary static magnetic orientation of the white dwarf, and their variation with orientation is presented. For high inclinations of the accreting pole to the orbital plane the component of the accretion torque parallel to this plane can be comparable to its perpendicular component. It is shown that the parallel component of the torque is still significant relative to the perpendicular component if material links to the white dwarf's magnetic field well away from the L 1 region. (author)

UNVEILING THE NATURE OF IGR J17177-3656 WITH X-RAY, NEAR-INFRARED, AND RADIO OBSERVATIONS

International Nuclear Information System (INIS)

Paizis, A.; Nowak, M. A.; Wilms, J.; Chaty, S.; Corbel, S.; Rodriguez, J.; Del Santo, M.; Ubertini, P.; Chini, R.

2011-01-01

We report on the first broadband (1-200 keV) simultaneous Chandra-INTEGRAL observations of the recently discovered hard X-ray transient IGR J17177-3656 that took place on 2011 March 22, about two weeks after the source discovery. The source had an average absorbed 1-200 keV flux of about 8 x 10 -10 erg cm -2 s -1 . We extracted a precise X-ray position of IGR J17177-3656, α J2000 = 17 h 17 m 42. s 62, δ J2000 = -36 0 56'04.''5 (90% uncertainty of 0.''6). We also report Swift, near-infrared, and quasi-simultaneous radio follow-up observations. With the multi-wavelength information at hand, we propose IGR J17177-3656 is a low-mass X-ray binary, seen at high inclination, probably hosting a black hole.

Continuous brightening of IGR J17473-2721

DEFF Research Database (Denmark)

Baldovin Saavedra, C.; Chenevez, Jérôme; Kuulkers, E.

2008-01-01

Renewed accretion activity has been reported by Swift/XRT (ATel #1459), XTE/PCA (ATel #1460) and INTEGRAL/IBIS/ISGRI (ATel #1461) from the RXTE transient IGR J17473-2721 (= XTE J1747-274; ATels #467, #498) after the detection of an X-ray burst by SuperAGILE (ATel #1445). From the on-going Galactic...... bulge monitoring program (see ATels #1385, #1461) we report that the transient continues to brighten as seen with IBIS/ISGRI and JEM-X....

Minimum period and the gap in periods of Cataclysmic binaries

International Nuclear Information System (INIS)

Paczynski, B.; Sienkiewicz, R.

1983-01-01

The 81 minute cutoff to the orbital periods of hydrogen-rich cataclysmic binaries is consistent with evolution of those systems being dominated by angular momentum losses due to gravitational radiation. Unfortunately, many uncertainties, mainly poorly known atmospheric opacities below 2000 K, make is physically impossible to verify the quadrupole formula for gravitational radiation by using the observed cutoff at 81 minutes. The upper boundary of the gap in orbital periods observed at about 3 hours is almost certainly due to enhanced angular momentum losses from cataclysmic binaries which have longer periods. The physical mechanism of those losses is not identified, but a possible importance of stellar winds is pointed out. The lower boundary of the gap may be explained with the oldest cataclysmic binaries, whose periods evolved past the minimum at 81 minutes and reached the value of 2 hours within about 12 x 10 9 years after the binary had formed. Those binaries should have secondary components of only 0.02 solar masses, and their periods could be used to estimate ages of the oldest cataclysmic stars, and presumably the age of Galaxy. An alternative explanation for the gap requires that binaries should be detached while crossing the gap. A possible mechanism for this phenomenon is discussed. It requires the secondary components to be about 0.2 solar masses in the binaries just below the gap

A NEW SUB-PERIOD-MINIMUM CATACLYSMIC VARIABLE WITH PARTIAL HYDROGEN DEPLETION AND EVIDENCE OF SPIRAL DISK STRUCTURE

International Nuclear Information System (INIS)

Littlefield, C.; Garnavich, P.; Magno, K.; Applegate, A.; Pogge, R.; Irwin, J.; Marion, G. H.; Kirshner, R.; Vinkó, J.

2013-01-01

We present time-resolved spectroscopy and photometry of CSS 120422:111127+571239 (=SBS 1108+574), a recently discovered SU UMa-type dwarf nova whose 55 minute orbital period is well below the cataclysmic variable (CV) period minimum of ∼78 minutes. In contrast with most other known CVs, its spectrum features He I emission of comparable strength to the Balmer lines, implying a hydrogen abundance less than 0.1 of long-period CVs—but still at least 10 times higher than that in AM CVn stars. Together, the short orbital period and remarkable helium-to-hydrogen ratio suggest that mass transfer in CSS 120422 began near the end of the donor star's main-sequence lifetime, meaning that this CV is a strong candidate progenitor of an AM CVn system as described by Podsiadlowski et al. Moreover, a Doppler tomogram of the Hα line reveals two distinct regions of enhanced emission. While one is the result of the stream-disk impact, the other is probably attributable to spiral disk structure generated when material in the outer disk achieves a 2:1 orbital resonance with respect to the donor.

IGR J170626143 is an Accreting Millisecond X-Ray Pulsar

Science.gov (United States)

Strohmayer, Tod E.; Keek, Laurens

2017-01-01

We present the discovery of 163.65 Hz X-ray pulsations from IGR J17062-6143 in the only observation obtained from the source with the Rossi X-ray Timing Explorer. This detection makes IGR J17062-6143 the lowest frequency accreting millisecond X-ray pulsar presently known. The pulsations are detected in the 2-12 keV band with an overall significance of 4.3sigma and an observed pulsed amplitude of 5.54% +/-0.67% (in this band). Both dynamic power spectral and coherent phase timing analysis indicate that the pulsation frequency is decreasing during the approx. =1.2 ks observation in a manner consistent with orbital motion of the neutron star. Because the observation interval is short, we cannot precisely measure the orbital period; however, periods shorter than 17 minutes are excluded at 90% confidence. For the range of acceptable circular orbits the inferred binary mass function substantially overlaps the observed range for the AMXP population as a whole.

INTEGRAL detects renewed activity from IGR J11435-6109

DEFF Research Database (Denmark)

Fiocchi, M.; Chenevez, J.; Sguera, V.

2015-01-01

During a recent INTEGRAL public observation of Musca region, performed between 2015-12-11 17:54 and 2015-12-12 12:54 (UTC), renewed activity from the transient X-ray pulsar IGR J11435-6109 has been detected. The 22-60 keV IBIS/ISGRI flux corresponds to (10+/-1) mCrab with an effective exposure time...

Hard X-ray activity of IGR J17473-2721

DEFF Research Database (Denmark)

Kuulkers, E.; Shaw, S.; Beckmann, V.

2008-01-01

Persistent X-ray activity has been reported by Swift/XRT (ATel #1459) and RXTE/PCA (ATel #1460) from the transient IGR J17473-2721 (= XTE J1747-274; ATels #467, #498) after the detection of an X-ray burst by SuperAGILE (ATel #1445). We report the detection of persistent activity at 18-100 keV wit...

New cataclysmic variables and other exotic binaries in the globular cluster 47 Tucanae*

Science.gov (United States)

Rivera Sandoval, L. E.; van den Berg, M.; Heinke, C. O.; Cohn, H. N.; Lugger, P. M.; Anderson, J.; Cool, A. M.; Edmonds, P. D.; Wijnands, R.; Ivanova, N.; Grindlay, J. E.

2018-04-01

We present 22 new (+3 confirmed) cataclysmic variables (CVs) in the non-core-collapsed globular cluster 47 Tucanae (47 Tuc). The total number of CVs in the cluster is now 43, the largest sample in any globular cluster so far. For the identifications we used near-ultraviolet (NUV) and optical images from the Hubble Space Telescope, in combination with X-ray results from the Chandra X-ray Observatory. This allowed us to build the deepest NUV CV luminosity function of the cluster to date. We found that the CVs in 47 Tuc are more concentrated towards the cluster centre than the main-sequence turn-off stars. We compared our results to the CV populations of the core-collapsed globular clusters NGC 6397 and NGC 6752. We found that 47 Tuc has fewer bright CVs per unit mass than those two other clusters. That suggests that dynamical interactions in core-collapsed clusters play a major role creating new CVs. In 47 Tuc, the CV population is probably dominated by primordial and old dynamically formed systems. We estimated that the CVs in 47 Tuc have total masses of ˜1.4 M⊙. We also found that the X-ray luminosity function of the CVs in the three clusters is bimodal. Additionally, we discuss a possible double degenerate system and an intriguing/unclassified object. Finally, we present four systems that could be millisecond pulsar companions given their X-ray and NUV/optical colours. For one of them we present very strong evidence for being an ablated companion. The other three could be CO or He white dwarfs.

Energy scaling of the "heartbeat" pulse width of GRS 1915+105, IGR J17091-3624, and MXB 1730-335 from Rossi-XTE observations

Science.gov (United States)

Maselli, A.; Capitanio, F.; Feroci, M.; Massa, F.; Massaro, E.; Mineo, T.

2018-04-01

We investigate some key aspects of the "heartbeat" variability consisting of series of bursts with a slow rise and a fast decay, thus far detected only in GRS 1915+105, IGR J17091-3624, and MXB 1730-335. A previous analysis based on BeppoSAX data of GRS 1915+105 revealed a hard-X delay (HXD), that is a lag of the burst rise at higher energies with respect to lower ones; this leads to narrower pulse widths, w, at higher energies. We here use some light curves of Rossi-XTE observations of GRS 1915+105 for a deeper analysis of this effect and search for its presence in those extracted from some IGR J17091-3624 and MXB 1730-335 observations performed with the same satellite. Our results show that, at variance with GRS 1915+105, no HXD is evident in the light curves of MXB 1730-335 and only a marginal HXD may be argued for IGR J17091-3624. For GRS 1915+105 we find a decreasing trend of the pulse width with energy following a power law w = A ṡ E-s with an index s ≈ 0.8. Furthermore, we confirm the increase of the HXD with the recurrence time Trec of the bursts in each series that was already found in previous works using BeppoSAX data. Based on a spectral analysis of these three sources we conclude that the differences highlighted in the properties of the "heartbeat" variability are probably related to the different accreting compact object and the eventual presence of a corona in these binary interacting systems.

Comments on the evolution and origin of cataclysmic binaries

International Nuclear Information System (INIS)

Whyte, C.A.; Eggleton, P.P.

1980-01-01

Aspects of the observational data on cataclysmic binaries are discussed and possible correlations between type of behaviour and binary period are noted. A gap between 2 and 3 hr in binary periods is judged to be real. A simple numerical procedure for evolving Roche-lobe-filling stars is described, and applied to white dwarf-red dwarf binaries for various mass loss and angular momentum loss mechanisms, and initial conditions. The results, in which the short-time-scale behaviour of the systems is ignored, are classified into four modes of evolution: normal, nuclear evolution dominated, angular momentum loss dominated and hydrodynamical. The clustering below 2 hr is interpreted in terms of evolution following the hydrodynamical mode, and it is suggested that both stars in such systems are of low mass. This may be the commonest type of cataclysmic binary. A possible explanation for the apparent clustering of classical novae to periods of 3 to 5 hr is given, and evolutionary schemes for cataclysmic binaries outlined. It is suggested that the short-period systems (approximately < 2 hr) arise mainly from late case B mass transfer in the original binary and the longer period systems mainly from case C. (author)

Broad-Band Variability in Accreting Compact Objects

Directory of Open Access Journals (Sweden)

S. Scaringi

2015-02-01

Full Text Available Cataclysmic variable stars are in many ways similar to X-ray binaries. Both types of systems possess an accretion disk, which in most cases can reach the surface (or event horizon of the central compact object. The main difference is that the embedded gravitational potential well in X-ray binaries is much deeper than those found in cataclysmic variables. As a result, X-ray binaries emit most of their radiation at X-ray wavelengths, as opposed to cataclysmic variables which emit mostly at optical/ultraviolet wavelengths. Both types of systems display aperiodic broad-band variability which can be associated to the accretion disk. Here, the properties of the observed X-ray variability in XRBs are compared to those observed at optical wavelengths in CVs. In most cases the variability properties of both types of systems are qualitatively similar once the relevant timescales associated with the inner accretion disk regions have been taken into account. The similarities include the observed power spectral density shapes, the rms-flux relation as well as Fourier-dependant time lags. Here a brief overview on these similarities is given, placing them in the context of the fluctuating accretion disk model which seeks to reproduce the observed variability.

Kilohertz QPOs, spectral state transitions and the distance to the neutron star X-ray transient IGR J17473-2721

DEFF Research Database (Denmark)

Altamirano, D.; Galloway, D.; Chenevez, Jérôme

2008-01-01

We report on RXTE monitoring observations of the transient X-ray binary IGR J17473-2721 since the beginning of its latest outburst on March 26th, 2008 (see ATEL #1445, #1459, #1460, #1461 and #1468). IGR J17473-2721 reached a maximum unabsorbed flux of ~1.30E-8 ergs cm-2 s-1 (2-10 keV, assuming n...

IGR J17464-3213 (= H1743-322) is active again

DEFF Research Database (Denmark)

Kuulkers, E.; Chenevez, Jérôme; Altamirano, D.

2011-01-01

The INTEGRAL Galactic bulge (GB) monitoring program observations on UT April 6, 2011, 04:11-07:53 show that IGR J17464-3213 (= H1743-322) started another outburst. The observed JEM-X fluxes are 11 +/- 2 and 26 +/- 4 mCrab in the 3-10 and 10-25 keV energy bands, respectively, while the observed IB...

ON THE NEAR-INFRARED IDENTIFICATION OF THE INTEGRAL SOURCE IGR J16328–4726

Energy Technology Data Exchange (ETDEWEB)

Persi, P.; Fiocchi, M.; Bazzano, A.; Ubertini, P.; Parisi, P. [INAF/IAPS-Roma, Via fosso del cavaliere, 100, I-00133 Roma (Italy); Tapia, M. [Instituto de Astronomía, Universidad Nacional Autónoma de México, Ensenada, B.C. (Mexico); Roth, M., E-mail: paolo.persi@iaps.inaf.it [Las Campanas Observatory, Carnegie Institution of Washington, La Serena (Chile)

2015-07-15

The aim of this work is to identify the infrared (IR) counterpart of the Galactic high-mass X-ray binary IGR J16328–4726 discovered by the INTEGRAL satellite, and to derive the extinction and distance to the system. We present new deep sub-arcsecond JHK{sub s} imaging and low-resolution near-IR spectroscopy in the 1.5 and 2.4 μm range of IGR J16328–4726. We report the presence of two near-IR stellar sources separated by about 1.″8 at the location of the unresolved 2MASS source J16323791–4723409, previously considered to be the near-IR counterpart of the X-ray source. From the analysis of their near-IR colors and spectra as well as accurate positions, we uniquely identify the true IR counterpart of IGR J16328–4726. Our 1.5–2.4 μm spectrum of this star is consistent with the published classification O8Iafpe. Assuming this, and in combination with new JHK{sub s} photometry, a reddening A{sub V} = 23.6 ± 0.7 and a distance of 7.2 ± 0.3 kpc from the Sun are derived.

Outburst from the SFXT IGR J17544-2619 detected by INTEGRAL

DEFF Research Database (Denmark)

Paizis, A.; Kuulkers, E.; Chenevez, J.

2015-01-01

During public INTEGRAL Galactic bulge monitoring observations (ATel #438) performed on 2015 February 20-21 at UT 23:04-02:45, we detected the SFXT IGR J17544-2619 (see ATel #7137 for the recent Swift detection of the source outburst). The source was detected using IBIS/ISGRI in the 18-40 keV rang...

IGR J17062–6143 Is an Accreting Millisecond X-Ray Pulsar

Energy Technology Data Exchange (ETDEWEB)

Strohmayer, Tod [Astrophysics Science Division and Joint Space-Science Institute, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Keek, Laurens [X-ray Astrophysics Laboratory, NASA/GSFC and CRESST and the Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)

2017-02-20

We present the discovery of 163.65 Hz X-ray pulsations from IGR J17062−6143 in the only observation obtained from the source with the Rossi X-ray Timing Explorer . This detection makes IGR J17062−6143 the lowest-frequency accreting millisecond X-ray pulsar presently known. The pulsations are detected in the 2–12 keV band with an overall significance of 4.3 σ and an observed pulsed amplitude of 5.54% ± 0.67% (in this band). Both dynamic power spectral and coherent phase timing analysis indicate that the pulsation frequency is decreasing during the ≈1.2 ks observation in a manner consistent with orbital motion of the neutron star. Because the observation interval is short, we cannot precisely measure the orbital period; however, periods shorter than 17 minutes are excluded at 90% confidence. For the range of acceptable circular orbits the inferred binary mass function substantially overlaps the observed range for the AMXP population as a whole.

Mind the Gap when Data Mining the Ritter-Kolb Cataclysmic Variable Catalogue

Science.gov (United States)

Sparks, Warren M.; Sion, Edward M.

2017-01-01

The cataclysmic variable (CV) binary consists of a white dwarf primary and a low-mass secondary which overflows its Roche lobe. The Ritter-Kolb catalogue (2003, A&A, 404, 301) is a collection (~1000) of CV binaries and related objects. We have mined this catalogue for CVs with unevolved secondaries whose mass ratio (secondary/primary) is known (~130). A plot of the secondary mass verses the log of the orbital period exhibits the well-known period gap at 2-3 hrs. In addition, this plot shows that the secondary masses just above the period gap are collectively much larger than those just below. The average of the first ten secondary masses above the period is 180% larger than the average below the gap.The disrupted magnetic braking hypothesis (Howell, Nelson, and Rappaport 2001, ApJ, 550, 897 [HNR]) predicts that when the secondary becomes fully convective, the magnetic braking, which has driven the secondary out of thermal equilibrium, stops. In adjusting to thermal equilibrium the secondary shrinks below its Roche lobe and no longer loses mass. The binary system ceases to appear as a CV until gravitational radiation loss brings the secondary back in contact with its Roche lobe. This scenario is at odds with the apparent secondary mass loss across the period gap. Either the secondary continues to lose mass while crossing the period gap or the secondary masses are miscalculated!Magnetic braking causes the secondary to expand or inflate larger than its single star counterpart. Any orbital parameter calculation which assumes a radius-mass relationship based on single main-sequence stars will overestimate the mass of the secondary. We can approximate this mass overestimation from calculations by HNR which take into account the thermal heating from magnetic braking. Using this approximation as a first-order correction to the secondary mass, we replot the deflated secondary mass versus the binary period. The deflated masses immediately above and below the period gap are

VizieR Online Data Catalog: Radial velocities of 35 cataclysmic variables (Thorstensen+, 2016)

Science.gov (United States)

Thorstensen, J. R.; Alper, E. H.; Weil, K. E.

2017-02-01

We present spectroscopic follow-up observations of 35 newly discovered cataclysmic variables (CVs), 32 of which were found by the Catalina Real Time Transient Surveys (CRTS; Drake et al. 2009, Cat. J/ApJ/696/870; Drake et al. 2014, Cat. J/MNRAS/441/1186; Breedt et al. 2014, Cat. J/MNRAS/443/3174), ASAS-SN (Shappee et al. 2014ApJ...788...48S), and/or MASTER (Lipunov et al. 2010AdAst2010E..30L). All our observations are from Michigan-Dartmouth-MIT (MDM) Observatory on Kitt Peak, Arizona. For nearly all the spectra, we used the "modspec" spectrograph (a description of the modspec can be found at http://mdm.kpno.noao.edu/Manuals/ModSpec/modspec_man.html) with a 600line/mm grating. We mostly used a SITe 20482 CCD detector, which yielded 2Å/pixel from 4210 to 7500Å, with declining throughput toward the ends of the spectral range. When this detector was unavailable, we used a very similar 10242 SITe detector ("Templeton"), which covered 4660 to 6730Å. The modspec was mounted mostly on the 2.4m Hiltner telescope, but for some of the brighter objects, we used the 1.3m McGraw-Hill telescope. For a few of the 1.3m spectra, we used the Mark III grism spectrograph, which covered 4580 to 6850Å at 2.3Å/pixel. On both telescopes and with both spectrographs, we used an Andor Ikon camera to view the reflective slit jaws through a microscope and guided the telescope with a separate off-axis guider. With this arrangement we could place any object that was bright enough for a usable spectrum in the slit and track it accurately even if the portion of the light spilling onto the slit jaws was invisible. Our emission-line radial velocities are almost entirely of Hα, since it almost always gives the best signal-to-noise ratio with our instrument. (3 data files).

Hydrodynamic ejection of bipolar flows from objects undergoing disk accretion: T Tauri stars, massive pre-main-sequence objects, and cataclysmic variables

International Nuclear Information System (INIS)

Torbett, M.V.

1984-01-01

A general mechanism is presented for generating pressure-driven winds that are intrinsically bipolar from objects undergoing disk accretion. The energy librated in a boundary layer shock as the disk matter impacts the central object is shown to be sufficient to eject a fraction βapprox.10 -2 to 10 -3 of the accreted mass. These winds are driven by a mechanism that accelerates the flow perpendicular to the plane of the disk and can therefore account for the bipolar geometry of the mass loss observed near young stars. The mass loss contained in these winds is comparable to that inferred for young stars. Thus, disk accretion-driven winds may constitute the T Tauri phase of stellar evolution. This mechanism is generally applicable, and thus massive pre-main-sequence objects as well as cataclysmic variables at times of enhanced accretion are predicted to eject bipolar outflows as well. Unmagnetized accreting neutron stas are also expected to eject bipolar flows. Since this mechanism requires stellar surfaces, however, it will not operate in disk accretion onto black holes

The Peculiar Evolutionary History of IGR J17480-2446 in Terzan 5

NARCIS (Netherlands)

Patruno, A.; Ali Alpar, M.; van der Klis, M.; van den Heuvel, E.P.J.

2012-01-01

The low-mass X-ray binary (LMXB) IGR J17480-2446 in the globular cluster Terzan 5 harbors an 11 Hz accreting pulsar. This is the first object discovered in a globular cluster with a pulsar spinning at such low rate. The accreting pulsar is anomalous because its characteristics are very different

INTEGRAL confirms that XTE J1728-295 = IGR J17285-2922

DEFF Research Database (Denmark)

Turler, Marc; ., .; Brandt, Søren Kristian

2010-01-01

-40 keV and 40-80 keV energy bands, respectively. The average ISGRI spectrum can be well described (reduced chi^2 of 0.8 for 8 degrees of freedom) by a simple power-law of index 2.1+/-0.5 (uncertainty at 68% c.l.) and a 20-80 keV flux of 9.8e-11 erg/s/cm^2. The best-determined position with a 90......% confinement radius of 2.8 arcmin (Gros et al., 2003, A&A, L179) is (RA,DEC)=(262.172,-29.325), fully consistent with the location of the Swift/XRT Soft X-ray counterpart (ATel #2824). IGR J17285-2922 was not detected by JEM-X with a 3-sigma upper limit of about 12 mCrab (3-11 keV). This is consistent....... The coincidence of the renewed low-level activity of IGR J17285-2922 in the hard X-rays with the reported X-ray outburst of XTE J1728-295 (ATel #2823) and the positional coincidence with the proposed Soft X-ray counterpart (ATel #2824) strengthen the suggestion that the two sources are actually the same object...

Faulkes Telescope monitoring of the current outburst of IGR J00291+5934

NARCIS (Netherlands)

Russell, D.M.; Lewis, F.; Linares, M.; Roche, P.; Maitra, D.

2008-01-01

As part of an optical monitoring project of low-mass X-ray binaries (Lewis et al. 2008, http://adsabs.harvard.edu/abs/2008AIPC.1010..204L), we report on recent observations just prior to, and during the current outburst of the millisecond X-ray pulsar IGR J00291+5934 (ATel #1660, #1664, #1665). The

Short-term biochemical ill effects of insect growth regulator (IGR) pesticides in Cyphoderus javanus Borner (Collembola: Insecta) as potential biomarkers of soil pollution.

Science.gov (United States)

Saha, Ipsita; Joy, V C

2016-02-01

The insect growth regulator (IGR) chemicals are considered as safe alternatives to synthetic organic pesticides, but only scant information are available on their possible impact on non-target and ecologically important soil insect fauna of croplands. Previous studies by the authors showed that recommended agricultural doses of IGRs buprofezin (Applaud 25SC at 250 g a.i. ha(-1)), flubendiamide (Takumi 20WG at 50 g a.i. ha(-1)) and novaluron (Rimon 10EC at 100 g a.i. ha(-1)) produced less mortality of adults of a non-target soil insect Cyphoderus javanus Borner (Collembola) but decreased major life history parameters namely moulting, fecundity and egg hatching success. This detritivorous microarthropod is very sensitive to soil characteristics and is ecologically relevant to the tropical soils. Present microcosm study showed strong biochemical impact of the above doses of IGRs on tissue nutrient levels and digestive enzyme activities in C. javanus within 7 days of exposure to treated sandy loam soil. The levels of tissue proteins, carbohydrates, lipids and free amino acids declined significantly and persistently in the specimens reared in IGR-treated soils than in the specimens of untreated soil. Similarly, α-amylase, cellulase and protease activities declined significantly in the specimens of IGR-treated soil. These nutritional scarcities would reduce metabolism, growth and reproduction in the affected insects. Therefore, the observed biochemical responses, especially the levels of tissue proteins, carbohydrates and α-amylase activity in C. javanus are early warning indices and potential biomarkers of soil pollution in croplands.

IGR J19294+1816: a new Be-X-ray binary revealed through infrared spectroscopy

Science.gov (United States)

Rodes-Roca, J. J.; Bernabeu, G.; Magazzù, A.; Torrejón, J. M.; Solano, E.

2018-05-01

The aim of this work is to characterize the counterpart to the INTErnational Gamma-Ray Astrophysics Laboratory high-mass X-ray binary candidate IGR J19294+1816 so as to establish its true nature. We obtained H-band spectra of the selected counterpart acquired with the Near Infrared Camera and Spectrograph instrument mounted on the Telescopio Nazionale Galileo 3.5-m telescope which represents the first infrared spectrum ever taken of this source. We complement the spectral analysis with infrared photometry from UKIDSS, 2MASS, WISE, and NEOWISE data bases. We classify the mass donor as a Be star. Subsequently, we compute its distance by properly taking into account the contamination produced by the circumstellar envelope. The findings indicate that IGR J19294+1816 is a transient source with a B1Ve donor at a distance of d = 11 ± 1 kpc, and luminosities of the order of 1036-37 erg s-1, displaying the typical behaviour of a Be-X-ray binary.

Astrophysical parameters and orbital solution of the peculiar X-ray transient IGR J00370+6122

Science.gov (United States)

González-Galán, A.; Negueruela, I.; Castro, N.; Simón-Díaz, S.; Lorenzo, J.; Vilardell, F.

2014-06-01

Context. BD + 60° 73 is the optical counterpart of the X-ray source IGR J00370+6122, a probable accretion-powered X-ray pulsar. The X-ray light curve of this binary system shows clear periodicity at 15.7 d, which has been interpreted as repeated outbursts around the periastron of an eccentric orbit. Aims: We aim to characterise the binary system IGR J00370+6122 by deriving its orbital and physical parameters. Methods: We obtained high-resolution spectra of BD + 60° 73 at different epochs. We used the fastwind code to generate a stellar atmosphere model to fit the observed spectrum and obtain physical magnitudes. The synthetic spectrum was used as a template for cross-correlation with the observed spectra to measure radial velocities. The radial velocity curve provided an orbital solution for the system. We also analysed the RXTE/ASM and Swift/BAT light curves to confirm the stability of the periodicity. Results: BD + 60° 73 is a BN0.7 Ib low-luminosity supergiant located at a distance ~3.1 kpc, in the Cas OB4 association. We derive Teff = 24 000 K and log gc = 3.0, and chemical abundances consistent with a moderately high level of evolution. The spectroscopic and evolutionary masses are consistent at the 1-σ level with a mass M∗ ≈ 15 M⊙. The recurrence time of the X-ray flares is the orbital period of the system. The neutron star is in a high-eccentricity (e = 0.56 ± 0.07) orbit, and the X-ray emission is strongly peaked around orbital phase φ = 0.2, though the observations are consistent with some level of X-ray activity happening at all orbital phases. Conclusions: The X-ray behaviour of IGR J00370+6122 is reminiscent of "intermediate" supergiant X-ray transients, though its peak luminosity is rather low. The orbit is somewhat wider than those of classical persistent supergiant X-ray binaries, which when combined with the low luminosity of the mass donor, explains the low X-ray luminosity. IGR J00370+6122 will very likely evolve towards a persistent

Radio emission from the nova-like variable AC Cancri and the symbiotic variable AG Draconis

International Nuclear Information System (INIS)

Torbett, M.V.; Campbell, B.; Mount Wilson and Las Campanas Observatories, Pasadena, CA)

1987-01-01

Radio emission at 6 cm has been detected from the nova-like cataclysmic variable AC Cnc and the symbiotic variable AG Dra. The AC Cnc observation constitutes the first radio detection in this class of objects. The AG Dra source is probably resolved and appears to show asymmetric, extended structure. The radio emission can best be explained by thermal bremsstrahlung. 26 references

Research of Precataclysmic Variables with Radius Excesses

Science.gov (United States)

Deminova, N. R.; Shimansky, V. V.; Borisov, N. V.; Gabdeev, M. M.; Shimanskaya, N. N.

2017-06-01

The results of spectroscopic observations of the pre-cataclysmic variable NSVS 14256825, which is a HW Vir binary system, were analyzed. The chemical composition is determined, the radial velocities and equivalent widths of a given star are measured. The fundamental parameters of the components were determined (R1 = 0.166 R⊙ , M2 = 0.100 M⊙ , R2 = 0.122 R⊙). It is shown that the secondary component has a mass close to the mass of brown dwarfs. A comparison of two close binary systems is made: HS 2333 + 3927 and NSVS 14256825. A radius-to-mass relationship for the secondary components of the studied pre-cataclysmic variables is constructed. It is concluded that an excess of radii relative to model predictions for MS stars is observed in virtually all systems.

Quasi-periodic Pulse Amplitude Modulation in the Accreting Millisecond Pulsar IGR J00291+5934

Energy Technology Data Exchange (ETDEWEB)

Bult, Peter [Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Doesburgh, Marieke van; Klis, Michiel van der [Anton Pannekoek Institute, University of Amsterdam, Postbus 94249, 1090 GE Amsterdam (Netherlands)

2017-08-20

We introduce a new method for analyzing the aperiodic variability of coherent pulsations in accreting millisecond X-ray pulsars (AMXPs). Our method involves applying a complex frequency correction to the time-domain light curve, allowing for the aperiodic modulation of the pulse amplitude to be robustly extracted in the frequency domain. We discuss the statistical properties of the resulting modulation spectrum and show how it can be correlated with the non-pulsed emission to determine if the periodic and aperiodic variability are coupled processes. Using this method, we study the 598.88 Hz coherent pulsations of the AMXP IGR J00291+5934 as observed with the Rossi X-ray Timing Explorer and XMM-Newton . We demonstrate that our method easily confirms the known coupling between the pulsations and a strong 8 mHz quasi-periodic oscillation (QPO) in XMM-Newton observations. Applying our method to the RXTE observations, we further show, for the first time, that the much weaker 20 mHz QPO and its harmonic are also coupled with the pulsations. We discuss the implications of this coupling and indicate how it may be used to extract new information on the underlying accretion process.

Quasi-Periodic Pulse Amplitude Modulation in the Accreting Millisecond Pulsar IGR J00291+5934

Science.gov (United States)

Bult, Peter; van Doesburgh, Marieke; van der Klis, Michiel

2017-01-01

We introduce a new method for analyzing the a periodic variability of coherent pulsations in accreting millisecond X-ray pulsars (AMXPs). Our method involves applying a complex frequency correction to the time-domain lightcurve, allowing for the aperiodic modulation of the pulse amplitude to be robustly extracted in the frequency domain. We discuss the statistical properties of the resulting modulation spectrum and show how it can be correlated with the non-pulsed emission to determine if the periodic and a periodic variability are coupled processes. Using this method, we study the 598.88 Hz coherent pulsations of the AMXP IGR J00291+5934 as observed with the Rossi X-ray Timing Explorer and XMM-Newton. We demonstrate that our method easily confirms the known coupling between the pulsations and a strong 8 mHz quasi-periodic oscillation (QPO) in XMM-Newton observations. Applying our method to the RXTE observations, we further show, for the first time, that the much weaker 20 mHz QPO and its harmonic are also coupled with the pulsations. We discuss the implications of this coupling and indicate how it may be used to extract new information on the underlying accretion process.

Side Effects of IGR Cyromazine on Nasonia vitripennis (Hymenoptera: Pteromalidae, a Parasitic Wasp of House Fly Pupae

Directory of Open Access Journals (Sweden)

B Vazirianzadeh

2008-12-01

Full Text Available "nBackground: Combination of cyromazine as an Insect Growth Regulator (IGR and Nasonia vitripennis (Hymenop¬tera: Pteromalidae a parasitic wasp may be an effective tool for reducing the house-fly populations in poultry houses and livestock farms. This study was conducted to assess the side effects of the IGR cyromazine on the level of parasit¬ism and numbers and the longevity of emerged N. vitripennis parasitoids from house fly pupae."nMethods: Cyromazine treated cloth target was used as the contaminating method of the parasitoids which was ap¬plied in this research study. "nResults: The Weibull distribution showed that there was no significant difference among controls and cyromazine treated targets for longevity data. There was no significant effect of cyromazine on the level of parasitism of N. vitripennis using 2 test. One-way ANOVA showed that the actual numbers emerging were significantly higher in the control than in two cyromazine treatments; however, it is a useful phenomenon because of reducing the hyperparasitism."nConclusion: There is a good consistency between using N. vitripennis and 1.1% or 0.9% cyromazine treated targets. There¬fore cyromazine treated targets can be applied as a safe delivery vehicle for applying the cyromazine IGR in the poultry houses and livestock farms in an Integrated Pest Management (IPM program.

Side Effects of IGR Cyromazine on Nasonia vitripennis (Hymenoptera: Pteromalidae, a Parasitic Wasp of House Fly Pupae

Directory of Open Access Journals (Sweden)

B Vazirianzadeh

2008-12-01

Full Text Available Background: Combination of cyromazine as an Insect Growth Regulator (IGR and Nasonia vitripennis (Hymenop¬tera: Pteromalidae a parasitic wasp may be an effective tool for reducing the house-fly populations in poultry houses and livestock farms. This study was conducted to assess the side effects of the IGR cyromazine on the level of parasit¬ism and numbers and the longevity of emerged N. vitripennis parasitoids from house fly pupae.Methods: Cyromazine treated cloth target was used as the contaminating method of the parasitoids which was ap¬plied in this research study. Results: The Weibull distribution showed that there was no significant difference among controls and cyromazine treated targets for longevity data. There was no significant effect of cyromazine on the level of parasitism of N. vitripennis using 2 test. One-way ANOVA showed that the actual numbers emerging were significantly higher in the control than in two cyromazine treatments; however, it is a useful phenomenon because of reducing the hyperparasitism.Conclusion: There is a good consistency between using N. vitripennis and 1.1% or 0.9% cyromazine treated targets. There¬fore cyromazine treated targets can be applied as a safe delivery vehicle for applying the cyromazine IGR in the poultry houses and livestock farms in an Integrated Pest Management (IPM program.

INTEGRAL Galactic Plane Scans detect enhanced activity from the HMXBs IGR J19294+1816 and 4U 1909+07

DEFF Research Database (Denmark)

Drave, S. P.; Sguera, V.; Fiocchi, M.

2013-01-01

exposures of ~7.9 and ~2.9 ks respectively but neither were detected, with 6sigma flux upper limits of 6 mCrab and 8 mCrab in the 3-10 keV band respectively. 4U 1909+07 is a wind-fed SgXRB pulsar whose past variability is consistent with the enhanced flux detected in these observations. IGR J19294......+1816 is a likely BeXRB pulsar that displays recurrent outbursts, of an approximate duration of 2 months (Bozzo et al. 2011, A&A, 531, A65), modulated on the 117.2 day orbital period (Corbet and Krimm 2009, ATel #2008) along with additional fast flaring behaviour, more typical of Supergiant Fast X-ray Transients...

Experiment calculated ascertainment of factors affecting the energy release in IGR reactor core

International Nuclear Information System (INIS)

Kurpesheva, A.M.; Zhotabayev, Zh.R.

2006-01-01

Full text: At present energy supply resources problem is important. Nuclear reactors can, of course, solve this problem, but at the same time there is another issue, concerning safety exploitation of nuclear reactors. That is why, for the last seven years, such experiments as 'Investigation of the processes, conducting severe accidents with core melting' are being carried out at our IGR (impulse graphite reactor) reactor. Leaving out other difficulties of such experiments, it is necessary to notice, that such experiments require more accurate IGR core energy release calculations. The final aim of the present research is verification and correction of the existing method or creation of new method of IGR core energy release calculation. IGR reactor is unique and there is no the same reactor in the world. Therefore, application of the other research reactor methods here is quite useful. This work is based on evaluation of factors affecting core energy release (physical weight of experimental device, different configuration of reactor core, i.e. location of absorbers, initial temperature of core, etc), as well as interference of absorbers group. As it is known, energy release is a value of integral reactor power. During experiments with rays, Reactor power depends on currents of ion production chambers (IPC), located round the core. It is worth to notice that each ion production chamber (IPC) in the same start-up has its own ratio coefficient between IPC current and reactor present power. This task is complicated due to 'IPC current - reactor power' ratio coefficients, that change continuously, probably, because of new loading of experimental facility and different position of control rods. That is why, in order to try about reactor power, before every start-up, we have to re-determine the 'IPC current - reactor power' ratio coefficients for each ion production chamber (IPC). Therefore, the present work will investigate the behavior of ratio coefficient within the

Minimising radiation exposure due to source assembly-related deficiencies in industrial gamma radiography exposure devices (IGREDs)

International Nuclear Information System (INIS)

Sivaraman, G.; Kannan, R.; Nandakumar, A.N.; Subrahmanya, M.J.; Murthy, B.K.S.

2000-01-01

Industrial radiographers receive higher doses as compared to radiation workers in medicine, agriculture, research, etc. Hence, it is essential that industrial gamma radiography exposure device (IGRED) be provided with efficient and effective safety systems in their design and operation to ensure smooth operation and minimise radiation exposures to the operators and public. Even though all these exposure devices have undergone stringent tests for radiographic exposure devices under international or national standards, certain deficiencies were noticed when scientists of Radiological Physics and Advisory Division (RPAD), carried out radiography equipment inspection of IGREDs. Some examples are briefly described here. The use of depleted Uranium pencil in some models led to the source pencil getting jammed due to formation of Uranium Oxide and bulging of the pencil. The solution was to replace the uranium pencil with high quality tungsten pencils or stainless steel clad pencils. In one type of pencils the source assembly would flare up after some use obstructing the smooth movement of the source assembly. The suggestion to subject the source assemblies to heat treatment solved the problem. In another type, the source pencil was getting corroded in high humid condition and affected the source movement. When the composition of the source pencil was changed it could withstand high humid condition. Another model had a hook type coupling between source assembly and drive cable. This often resulted in disengagement of the source assembly from the drive cable. Suggestions were made to change the coupling to ball and socket coupling for smooth functioning and for 'fail-safe' operation. During early days of the use of remote operated IGRED, in one particular model of the IGRED, the Iridium source wafers were directly loaded in a single encapsulation. Once the welding gave way and the source wafers got strewn. Subsequently, the source pellets/wafers were doubly encapsulated

Chandra position of IGR J17454-2919 and discovery of a possible NIR counterpart

DEFF Research Database (Denmark)

Paizis, A.; Nowak, M.; Chati, S.

2015-01-01

On 2014 November 3, we observed the recently discovered INTEGRAL source IGR J17454-2919 (ATels #6530, #6574 and #6602) with Chandra HETGS for 20ks. The J2000.0 Chandra position we obtain is RA: 17 45 27.689 DEC: -29 19 53.83 (90% uncertainty of 0.6") This position (2.4" away from the Swift positi...

Earlier activity from XTE J1739-302/IGR J17391-3021 detected by INTEGRAL

DEFF Research Database (Denmark)

Chenevez, Jérôme; Beckmann, V.; Kuulkers, E.

2008-01-01

The recently reported outburst from the supergiant fast X-ray transient XTE J1739-302/IGR J17391-3021 (ATEL #1466) began already about five hours earlier than the Swift/BAT trigger on 2008-04-08. The INTEGRAL/JEM-X monitor detected a flare starting at 16:18 (UTC) on the same day during recent Gal...

Discovery of a new X-ray transient IGR J16283-4838 with INTEGRAL

DEFF Research Database (Denmark)

Soldi, S.; Brandt, Søren Kristian; Garau, A.

2005-01-01

We report the discovery of a new source by the IBIS/ISGRI detector on board INTEGRAL. The new source, IGR J16283-4838, was detected during a core program observation of the Norma Arm between 2005 April 7 13:56:50 U.T. and April 9 04:44:23 U.T., with a flux of ~3.6 mCrab in the 20-60 keV band and ...

Krakatoa Erupts!: Using a Historic Cataclysm to Teach Modern Science

Science.gov (United States)

Clary, Renee; Wandersee, James

2011-01-01

Through integration of geology, biology, chemistry, and the history of science, the historic Krakatoa eruption offers a unique portal for student inquiry in the classroom. Students are inherently fascinated by natural disasters, and modern comparisons to the Krakatoa cataclysm are as close as the day's news. This article uses the historic Krakatoa…

Swift observations of the accreting millisecond pulsar IGR J17498-2921 : From outburst to quiescence

NARCIS (Netherlands)

Linares, M.; Bozzo, E.; Altamirano, D.; Degenaar, N.; Wijnands, R.; Soleri, P.; Belloni, T.; Di Salvo, T.; D'Ai, A.; Papitto, A.; Riggio, A.; Burderi, L.

Swift has been monitoring the accreting millisecond pulsar IGR J17498-2921 since the start of its outburst in 2011 August 12 (ATels #3551, #3555, #3556). We detected two X-ray bursts on Aug. 18 and 28. During the first ~12 days the average persistent XRT count rate remained approximately constant at

On the Nature of the Hard X-Ray Sources SWIFT J1907.3-2050, IGR J12123-5802 and IGR J19552+0044

Science.gov (United States)

Bernardini, F.; deMartino, D; Mukai, K.; Falanga, M.; Andruchow, I.; Bonnet-Bidaud, J.-M.; Masetti, N.; GonzalezBuitrago, D. H.; Mouchet, M.; Tovmassian, G.

2014-01-01

The INTEGRAL and Swift hard X-ray surveys have identified a large number of new sources, among which many are proposed as Cataclysmic Variables (CVs). Here we present the first detailed study of three X-ray selected CVs, Swift J1907.3-2050, IGRJ12123-5802, and IGRJ19552+0044 based on XMM-Newton, Suzaku, Swift observations and ground based optical and archival nIR/IR data. Swift J1907.3-2050 is highly variable from hours to monthsyears at all wavelengths. No coherent X-ray pulses are detected but rather transient features. The X-ray spectrum reveals a multi-temperature optically thin plasma absorbed by complex neutral material and a soft black body component arising from a small area. These characteristics are remarkably similar to those observed in magnetic CVs. A supra-solar abundance of nitrogen could arise from nuclear processed material from the donor star. Swift J1907.3-2050 could be a peculiar magnetic CV with the second longest (20.82 h) binary period. IGRJ12123-5802 is variable in the X-rays on a timescale of approximately or greater than 7.6 h. No coherent pulsations are detected, but its spectral characteristics suggest that it could be a magnetic CV of the Intermediate Polar (IP) type. IGRJ19552+0044 shows two X-ray periods, approximately 1.38 h and approximately 1.69 h and a X-ray spectrum characterized by a multi-temperature plasma with little absorption.We derive a low accretion rate, consistent with a CV below the orbital period gap. Its peculiar nIR/IR spectrum suggests a contribution from cyclotron emission. It could either be a pre-polar or an IP with the lowest degree of asynchronism.

SWIFT-BAT HARD X-RAY SKY MONITORING UNVEILS THE ORBITAL PERIOD OF THE HMXB IGR J18219–1347

International Nuclear Information System (INIS)

La Parola, V.; Cusumano, G.; Segreto, A.; D'Aì, A.; Masetti, N.; D'Elia, V.

2013-01-01

IGR J18219–1347 is a hard X-ray source discovered by INTEGRAL in 2010. We have analyzed the X-ray emission of this source exploiting the Burst Alert Telescope (BAT) survey data up to 2012 March and the X-Ray Telescope (XRT) data that include also an observing campaign performed in early 2012. The source is detected at a significance level of ∼13 standard deviations in the 88 month BAT survey data, and shows a strong variability along the survey monitoring, going from high intensity to quiescent states. A timing analysis on the BAT data revealed an intensity modulation with a period of P 0 = 72.44 ± 0.3 days. The significance of this modulation is about seven standard deviations in Gaussian statistics. We interpret it as the orbital period of the binary system. The light curve folded at P 0 shows a sharp peak covering ∼30% of the period, superimposed to a flat level roughly consistent with zero. In the soft X-rays the source is detected only in 5 out of 12 XRT observations, with the highest recorded count rate corresponding to a phase close to the BAT folded light-curve peak. The long orbital period and the evidence that the source emits only during a small fraction of the orbit suggests that the IGR J18219–1347 binary system hosts a Be star. The broadband XRT+BAT spectrum is well modeled with a flat absorbed power law with a high-energy exponential cutoff at ∼11 keV

Discovery of 245 Hz burst oscillations from the accreting millisecond pulsar IGR J17511-3057

NARCIS (Netherlands)

Watts, A.L.; Altamirano, D.; Markwardt, C.B.; Strohmayer, T.E.

2009-01-01

RXTE observations of the bursting accreting millisecond X-ray pulsar IGR J17511-3057 (ATEL #2196, #2197, #2198) showed a short Type I X-ray burst on September 14th 2009. We detect strong burst oscillations at 245 Hz, very close to the spin frequency. Maximum Leahy power is in the range 130-215 in 3

On the history of the early meteoritic bombardment of the Moon: Was there a terminal lunar cataclysm?

Science.gov (United States)

Michael, Greg; Basilevsky, Alexander; Neukum, Gerhard

2018-03-01

This work revisits the hypothesis of the so-called 'lunar terminal cataclysm' suggested by Tera et al. (1973, 1974) as a strong peak in the meteorite bombardment of the Moon around 3.9 Ga ago. According to the hypothesis, most of the impact craters observed on the lunar highlands formed during this short time period and thus formed the majority of the lunar highland impact breccias and melts. The hypothesis arose from the observation that the ages of highland samples from all the lunar missions are mostly grouped around 3.9-4.0 Ga. Since those missions, however, radiometric dating techniques have progressed and many samples, both old and new, have been re-analyzed. Nevertheless, the debate over whether there was a terminal cataclysm persists. To progress in this problem we summarized results of 269 K-Ar datings (mostly made using the 40Ar-39Ar technique) of highland rocks represented by the Apollo 14, 15, 16, 17 and Luna 20 samples and 94 datings of clasts of the highland rocks from 23 lunar meteorites representing 21 localities on the lunar surface, and considered them jointly with the results of our modelling of the cumulative effect of the impact gardening process on the presence of impact melt of different ages at the near-surface of the Moon. The considered results of K-Ar dating of the Apollo-Luna samples of lunar highland rocks confirmed a presence of strong peak centered at 3.87 Ga. But since the time when the hypothesis of terminal cataclysm was suggested, it has become clear that this peak could be a result of sampling bias: it is the only prominent feature at the sites with an apparent domination of Imbrium basin ejecta (Apollo 14 and 15) and the age pattern is more complicated for the sites influenced not only by Imbrium ejecta but also that of other basins (Nectaris at the Apollo 16 site and Serenitatis at the Apollo 17 site). Our modelling shows that the cataclysm, if it occurred, should produce a strong peak in the measured age values but we see in

The Evolution of Cataclysmic Variables as Revealed by Their Donor Stars

Science.gov (United States)

Knigge, Christian; Baraffe, Isabelle; Patterson, Joseph

2011-06-01

We present an attempt to reconstruct the complete evolutionary path followed by cataclysmic variables (CVs), based on the observed mass-radius relationship of their donor stars. Along the way, we update the semi-empirical CV donor sequence presented previously by one of us, present a comprehensive review of the connection between CV evolution and the secondary stars in these systems, and reexamine most of the commonly used magnetic braking (MB) recipes, finding that even conceptually similar ones can differ greatly in both magnitude and functional form. The great advantage of using donor radii to infer mass-transfer and angular-momentum-loss (AML) rates is that they sample the longest accessible timescales and are most likely to represent the true secular (evolutionary average) rates. We show explicitly that if CVs exhibit long-term mass-transfer-rate fluctuations, as is often assumed, the expected variability timescales are so long that other tracers of the mass-transfer rate—including white dwarf (WD) temperatures—become unreliable. We carefully explore how much of the radius difference between CV donors and models of isolated main-sequence stars may be due to mechanisms other than mass loss. The tidal and rotational deformation of Roche-lobe-filling stars produces ~= 4.5% radius inflation below the period gap and ~= 7.9% above. A comparison of stellar models to mass-radius data for non-interacting stars suggests a real offset of ~= 1.5% for fully convective stars (i.e., donors below the gap) and ~= 4.9% for partially radiative ones (donors above the gap). We also show that donor bloating due to irradiation is probably smaller than, and at most comparable to, these effects. After calibrating our models to account for these issues, we fit self-consistent evolution sequences to our compilation of donor masses and radii. In the standard model of CV evolution, AMLs below the period gap are assumed to be driven solely by gravitational radiation (GR), while AMLs

THE EVOLUTION OF CATACLYSMIC VARIABLES AS REVEALED BY THEIR DONOR STARS

International Nuclear Information System (INIS)

Knigge, Christian; Baraffe, Isabelle; Patterson, Joseph

2011-01-01

We present an attempt to reconstruct the complete evolutionary path followed by cataclysmic variables (CVs), based on the observed mass-radius relationship of their donor stars. Along the way, we update the semi-empirical CV donor sequence presented previously by one of us, present a comprehensive review of the connection between CV evolution and the secondary stars in these systems, and reexamine most of the commonly used magnetic braking (MB) recipes, finding that even conceptually similar ones can differ greatly in both magnitude and functional form. The great advantage of using donor radii to infer mass-transfer and angular-momentum-loss (AML) rates is that they sample the longest accessible timescales and are most likely to represent the true secular (evolutionary average) rates. We show explicitly that if CVs exhibit long-term mass-transfer-rate fluctuations, as is often assumed, the expected variability timescales are so long that other tracers of the mass-transfer rate-including white dwarf (WD) temperatures-become unreliable. We carefully explore how much of the radius difference between CV donors and models of isolated main-sequence stars may be due to mechanisms other than mass loss. The tidal and rotational deformation of Roche-lobe-filling stars produces ≅ 4.5% radius inflation below the period gap and ≅ 7.9% above. A comparison of stellar models to mass-radius data for non-interacting stars suggests a real offset of ≅ 1.5% for fully convective stars (i.e., donors below the gap) and ≅ 4.9% for partially radiative ones (donors above the gap). We also show that donor bloating due to irradiation is probably smaller than, and at most comparable to, these effects. After calibrating our models to account for these issues, we fit self-consistent evolution sequences to our compilation of donor masses and radii. In the standard model of CV evolution, AMLs below the period gap are assumed to be driven solely by gravitational radiation (GR), while AMLs

System of automatic control over data Acquisition and Transmission to IGR NNC RK Data Center

International Nuclear Information System (INIS)

Komarov, I.I.; Gordienko, D.D.; Kunakov, A.V.

2005-01-01

Automated system for seismic and acoustic data acquisition and transmission in real time was established in Data Center IGR NNC RK, which functions very successively. The system monitors quality and volume of acquired information and also controls the status of the system and communication channels. Statistical data on system operation are accumulated in created database. Information on system status is reflected on the Center Web page. (author)

A new X-ray transient, IGR J17451-3022, discovered by INTEGRAL/JEM-X near the Galactic Centre

DEFF Research Database (Denmark)

Chenevez, Jérôme; Vandbaek Kroer, L.; Budtz-Jørgensen, Carl

2014-01-01

The JEM-X twin X-ray monitors on board the INTEGRAL satellite has detected a new X-ray transient during recent observations of the Galactic Centre and Bulge regions. The new source named IGR J17451-3022 has the following coordinates: R.A. = 266.27 Dec. = -30.38 with a 2arcmin 90% confidence radiu...

XMM-Newton and Swift spectroscopy of the newly discovered very faint X-ray transient IGR J17494-3030

NARCIS (Netherlands)

Armas Padilla, M.; Wijnands, R.; Degenaar, N.

2013-01-01

A growing group of low-mass X-ray binaries are found to be accreting at very faint X-ray luminosities of <1036 erg s−1 (2-10 keV). One such system is the new X-ray transient IGR J17494-3030. We present Swift and XMM-Newton observations obtained during its 2012 discovery outburst. The Swift

State Transition and Flaring Activity of IGR J17464-3213/H1743-322 with INTEGRAL SPI

Science.gov (United States)

Joinet, A.; Jourdain, E.; Malzac, J.; Roques, J. P.; Schönfelder, V.; Ubertini, P.; Capitanio, F.

2005-08-01

IGR J17464-3213, already known as the HEAO 1 transient source H1743-322, has been detected during a state transition by INTEGRAL SPI. We describe the spectral evolution and flaring activity of IGR J17464-3213/H1743-322 from 2003 March 21 to 2003 April 22. During the first part, the source followed a continuous spectral softening, with the peak of the spectral energy distribution shifting from 100 keV down to ~a few keV. However, the thermal disk and the hard X-ray components had a similar intensity, indicating that the source was in an intermediate state throughout our observations and evolving toward the soft state. In the second part of our observations, the RXTE ASM and INTEGRAL SPI light curves showed a strong flaring activity. Two flare events lasting about 1 day each have been detected with SPI and are probably due to instabilities in the accretion disk associated with the state transition. During these flares, the low (1.5-12 keV) and high (20-200 keV) energy fluxes monitored with the RXTE ASM and INTEGRAL SPI are correlated, and the spectral shape (above 20 keV) remains unchanged while the luminosity increases by a factor greater than 2.

Study of behavior of cermet fuel elements on IGR reactor under RIA type accident condition

International Nuclear Information System (INIS)

Vasil'ev, Yu.S.; Vurim, A.D.; Koltyshev, S.M.; Pakhnits, V.A.; Tukhvatulin, Sh.T.; Popov, V.V.; Ryzhkov, A.N.

1996-01-01

In 1993 December in IGR reactor of Inst. of Atomic Energy of National Nuclear Center of Republic of Kazakstan the second batch of in-pile testing of perspective cermet fuel elements under the condition, simulating RIA type accident was conducted. In the second batch of testing during eight start-ups 10 cermet fuel elements were examined. Among which 8 of monolith type and 2 fuel elements with false jacket beside cladding (FJF), as well as, 6 standard fuel elements of WWER-1000 type reactor with dioxide fuel were tested. 2 fuel elements - cermet and standard were placed into capsule filled with water. To measure energy release for the each start-up two fission monitor and inside core control gauge were placed. In all the start-ups operation mode of IGR was neutron pulse. Power of fuel element kept changing from 151 to 336 k W; energy release was 38-93 kJ/gr m 235 U; maximum temperature of cermet fuel was 1943-2173 K, of dioxide fuel - 1923-2843 K. The testing has demonstrated that operability of cermet fuel elements under reactivity accident condition with pulse width of 0,2 s is, at least, not less that operability of dioxide fuel elements, through advantages of cermet fuel under these conditions are revealed to the least extent

The orbital period in the supergiant fast X-ray transient IGR J16465--4507

OpenAIRE

Clark, D. J.; Sguera, V.; Bird, A. J; McBride, V. A.; Hill, A. B.; Scaringi, S.; Drave, S.; Bazzano, A.; Dean, A. J

2010-01-01

Timing analysis of the INTEGRAL-IBIS and Swift-BAT light curves of the Supergiant Fast X-ray Transient (SFXT) IGR J16465-4507 has identified a period of 30.32+/-0.02 days which we interpret as the orbital period of the binary system. In addition 11 outbursts (9 of which are previously unpublished) have been found between MJD 52652 to MJD 54764, all of which occur close to the region of the orbit we regard as periastron. From the reported flux outbursts, we found a dynamical range in the inter...

INTEGRAL Galactic Bulge monitoring: transient activity from KS 1741-293, MXB 1730-335, and IGR J17498-2921

DEFF Research Database (Denmark)

Chenevez, Jérôme; Brandt, Søren; Kuulkers, E.

2011-01-01

sigma upper limit of 10 mCrab (40-100 keV) A series of 15 type II bursts is detected when the source was inside the JEM-X field of view, with an average burst recurrence time of about four minutes. The new transient source IGR J17498-2921 (see, e.g., ATels #3551, #3556, #3558, #3568, #3606) is only...

IGR J17454-2919: a new X-ray transient found by INTEGRAL/JEM-X close to the Galactic Center

DEFF Research Database (Denmark)

Chenevez, Jérôme; Brandt, Søren; Budtz-Jørgensen, Carl

2014-01-01

The JEM-X twin X-ray monitors on board the INTEGRAL satellite have again detected a new X-ray transient during the latest observation of the Galactic Center region. The new source named IGR J17454-2919 is found less than 24 arcmin from the Galactic Center. The source appears in both JEM-X 3-10 ke...

Very-high-energy gamma-ray observations of pulsar wind nebulae and cataclysmic variable stars with MAGIC and development of trigger systems for IACTs

Science.gov (United States)

Lopez-Coto, Ruben

2015-07-01

lowest possible energy threshold with the LSTs of CTA. Together with this work, the trigger of the MAGIC telescopes was improved. We have simulated, tested and commissioned a new concept of stereoscopic trigger. This new system, that uses the information of the position of the showers on each of the MAGIC cameras, is dubbed "Topo-trigger". The scientific fraction of the thesis deals with galactic sources observed with the MAGIC telescopes. In Part III, I talk about the analysis of the VHE γ-ray emission of Pulsar Wind Nebulae (PWNe): the discovery of VHE γ-ray emission from the puzzling PWN 3C 58, the likely remnant of the SN 1181 AD and the weakest PWN detected at VHE to date; the characterization of the VHE tail of the Crab nebula by observing it at the highest zenith angles; and the search for an additional inverse Compton component during the Crab nebula flares reported by Fermi-LAT in the synchrotron regime. Part IV is concerned with searches for VHE γ-ray emission of cataclysmic variable stars. I studied, on a multiwavelength context, the VHE γ-ray nature of the previously claimed pulsed γ-ray emission of the cataclysmic variable AE Aqr. I also performed observations of novae and a dwarf nova to pinpoint the ac- celeration mechanisms taking place in this kind of objects and to discover a putative hadronic component of the soft γ-ray emission. A conclusion chapter summarizes all the work performed and lists prospects related with the topics treated in this thesis.

Spectral analysis of IGR J01572-7259 during its 2016 outburst

Science.gov (United States)

La Palombara, N.; Esposito, P.; Mereghetti, S.; Pintore, F.; Sidoli, L.; Tiengo, A.

2018-03-01

We report on the results of the XMM-Newton observation of IGR J01572-7259 during its most recent outburst in 2016 May, the first since 2008. The source reached a flux f ˜ 10-10 erg cm-2 s-1, which allowed us to perform a detailed analysis of its timing and spectral properties. We obtained a pulse period Pspin = 11.58208(2) s. The pulse profile is double peaked and strongly energy dependent, as the second peak is prominent only at low energies and the pulsed fraction increases with energy. The main spectral component is a power-law model, but at low energies, we also detected a soft thermal component, which can be described with either a blackbody or a hot plasma model. Both the EPIC and RGS spectra show several emission lines, which can be identified with the transition lines of ionized N, O, Ne, and Fe and cannot be described with a thermal emission model. The phase-resolved spectral analysis showed that the flux of both the soft excess and the emission lines vary with the pulse phase: the soft excess disappears in the first pulse and becomes significant only in the second, where also the Fe line is stronger. This variability is difficult to explain with emission from a hot plasma, while the reprocessing of the primary X-ray emission at the inner edge of the accretion disc provides a reliable scenario. On the other hand, the narrow emission lines can be due to the presence of photoionized matter around the accreting source.

Space Nuclear Facility test capability at the Baikal-1 and IGR sites Semipalatinsk-21, Kazakhstan

Science.gov (United States)

Hill, T. J.; Stanley, M. L.; Martinell, J. S.

1993-01-01

The International Space Technology Assessment Program was established 1/19/92 to take advantage of the availability of Russian space technology and hardware. DOE had two delegations visit CIS and assess its space nuclear power and propulsion technologies. The visit coincided with the Conference on Nuclear Power Engineering in Space Nuclear Rocket Engines at Semipalatinsk-21 (Kurchatov, Kazakhstan) on Sept. 22-25, 1992. Reactor facilities assessed in Semipalatinski-21 included the IVG-1 reactor (a nuclear furnace, which has been modified and now called IVG-1M), the RA reactor, and the Impulse Graphite Reactor (IGR), the CIS version of TREAT. Although the reactor facilities are being maintained satisfactorily, the support infrastructure appears to be degrading. The group assessment is based on two half-day tours of the Baikals-1 test facility and a brief (2 hr) tour of IGR; because of limited time and the large size of the tour group, it was impossible to obtain answers to all prepared questions. Potential benefit is that CIS fuels and facilities may permit USA to conduct a lower priced space nuclear propulsion program while achieving higher performance capability faster, and immediate access to test facilities that cannot be available in this country for 5 years. Information needs to be obtained about available data acquisition capability, accuracy, frequency response, and number of channels. Potential areas of interest with broad application in the U.S. nuclear industry are listed.

Cataclysm No More: New Views on the Timing and Delivery of Lunar Impactors.

Science.gov (United States)

Zellner, Nicolle E B

2017-09-01

If properly interpreted, the impact record of the Moon, Earth's nearest neighbour, can be used to gain insights into how the Earth has been influenced by impacting events since its formation ~4.5 billion years (Ga) ago. However, the nature and timing of the lunar impactors - and indeed the lunar impact record itself - are not well understood. Of particular interest are the ages of lunar impact basins and what they tell us about the proposed "lunar cataclysm" and/or the late heavy bombardment (LHB), and how this impact episode may have affected early life on Earth or other planets. Investigations of the lunar impactor population over time have been undertaken and include analyses of orbital data and images; lunar, terrestrial, and other planetary sample data; and dynamical modelling. Here, the existing information regarding the nature of the lunar impact record is reviewed and new interpretations are presented. Importantly, it is demonstrated that most evidence supports a prolonged lunar (and thus, terrestrial) bombardment from ~4.2 to 3.4 Ga and not a cataclysmic spike at ~3.9 Ga. Implications for the conditions required for the origin of life are addressed.

NuSTAR detection of a cyclotron line in the supergiant fast X-ray transient IGR J17544-2619

DEFF Research Database (Denmark)

Bhalerao, Varun; Romano, Patrizia; Tomsick, John

2015-01-01

that the compact object in IGR J17544-2619 is indeed a neutron star. This is the first measurement of the magnetic field in an SFXT. The inferred magnetic field strength, B = (1.45 +/- 0.03) x 1012 G (1 + z) is typical of neutron stars in X-ray binaries, and rules out a magnetar nature for the compact object. We...

Flares from a new Integral hard X-ray source, IGR J17407-2808, likely associated with the ROSAT source SBM 10

DEFF Research Database (Denmark)

Kretschmar, P.; Mereghetti, S.; Hermsen, W.

2004-01-01

This new hard X-ray source, IGR J17407-2808, is positionally coincident with a faint ROSAT source listed as no. 10 in the catalogue of sources in the Galactic Center region by Sidoli, Belloni & Mereghetti 2001, A&A 368, 835 and as 2RXP J174040.9-280852 in the ROSAT Source Browser. No other observ...

Polarimetry of magnetic catalysmic variables

Energy Technology Data Exchange (ETDEWEB)

Cropper, M

1985-01-01

The design and construction of an astronomical polarimeter is described and an evaluation made of its performance. Extensive observations of cataclysmic variables with emphasis on the AM Her and DQ Her classes are then presented. The polarimeter permitted simultaneous linear and circular polarisation measurements, or, by rearranging the order of the retarders in the beam, linear polarisation measurements alone, or circular polarisation measurements alone, with enhanced efficiency. Extensive sets of observations using the polarimeter were obtained for six of the ten AM Her variables. A comparison was made between the competing models for the cyclotron emission, showing that those which take into account the temperature structure of the accretion region provide the best results.

An Extreme X-ray Disk Wind in the Black Hole Candidate IGR J17091-3624

Science.gov (United States)

King, A. L.; Miller, J. M.; Raymond, J.; Fabian, A. C.; Reynolds, C. S.; Kallman, T. R.; Maitra, D.; Cackett, E. M.; Rupen, M. P.

2012-01-01

Chandra spectroscopy of transient stellar-mass black holes in outburst has clearly revealed accretion disk winds in soft, disk-dominated states, in apparent anti-correlation with relativistic jets in low/hard states. These disk winds are observed to be highly ionized. dense. and to have typical velocities of approx 1000 km/s or less projected along our line of sight. Here. we present an analysis of two Chandra High Energy Transmission Grating spectra of the Galactic black hole candidate IGR J17091-3624 and contemporaneous EVLA radio observations. obtained in 2011. The second Chandra observation reveals an absorption line at 6.91+/-0.01 keV; associating this line with He-like Fe XXV requires a blue-shift of 9300(+500/-400) km/ s (0.03c. or the escape velocity at 1000 R(sub schw)). This projected outflow velocity is an order of magnitude higher than has previously been observed in stellar-mass black holes, and is broadly consistent with some of the fastest winds detected in active galactic nuclei. A potential feature at 7.32 keV, if due to Fe XXVI, would imply a velocity of approx 14600 km/s (0.05c), but this putative feature is marginal. Photoionization modeling suggests that the accretion disk wind in IGR J17091-3624 may originate within 43,300 Schwarzschild radii of the black hole, and may be expelling more gas than accretes. The contemporaneous EVLA observations strongly indicate that jet activity was indeed quenched at the time of our Chandra observations. We discuss the results in the context of disk winds, jets, and basic accretion disk physics in accreting black hole systems

Type I X-ray bursts, burst oscillations and kHz quasi-periodic oscillations in the neutron star system IGR J17191−2821

NARCIS (Netherlands)

Altamirano, D.; Linares, M.; Patruno, A.; Degenaar, N.; Wijnands, R.; Klein-Wolt, M.; van der Klis, M.; Markwardt, C.; Swank, J.

2010-01-01

We present a detailed study of the X-ray energy and power spectral properties of the neutron star transient IGR J17191−2821. We discovered four instances of pairs of simultaneous kilohertz quasi-periodic oscillations (kHz QPOs). The frequency difference between these kHz QPOs is between 315 and 362

NICER Discovers the Ultracompact Orbit of the Accreting Millisecond Pulsar IGR J17062–6143

DEFF Research Database (Denmark)

Strohmayer, T. E.; Arzoumanian, Z.; Bogdanov, S.

2018-01-01

We present results of recent Neutron Star Interior Composition Explorer (NICER) observations of the accreting millisecond X-ray pulsar (AMXP) IGR J17062−6143 that show that it resides in a circular, ultracompact binary with a 38-minute orbital period. NICER observed the source for ≈26 ks over a 5...... of the neutron star. A coherent search for the orbital solution using the Z2 method finds a best-fitting circular orbit with a period of 2278.21 s (37.97 minutes), a projected semimajor axis of 0.00390 lt-s, and a barycentric pulsar frequency of 163.6561105 Hz. This is currently the shortest known orbital period...

THE XMM-Newton and integral observations of the Supergiant Fast X-Ray Transient IGR J16328-4726

OpenAIRE

Fiocchi, M.; Bazzano, A.; Natalucci, L.; Ubertini, P.; Sguera, V.; Bird, A. J.; Boon, C.M.; Persi, P.; Piro, L.

2016-01-01

The accretion mechanism producing the short flares observed from the Supergiant Fast X-ray Transients (SFXT) is still highly debated and forms a major part in our attempts to place these X-ray binaries in the wider context of the High Mass X-ray Binaries. We report on a 216 ks INTEGRAL observation of the SFXT IGR J16328-4726 (2014 August 24–27) simultaneous with two fixed-time observations with XMM-Newton (33 and 20 ks) performed around the putative periastron passage, in order to investigate...

The inter-outburst behavior of cataclysmic variables

International Nuclear Information System (INIS)

Szkody, P.; Mattei, J.A.; Waagen, E.O.; Stablein, C.

1990-01-01

Existing International Ultraviolet Explorer (IUE) and American Association of Variable Star Observers (AAVSO) archive data was used to accomplish a large scale study of what happens to the ultraviolet flux of accretion disk systems during the quiescent intervals between outbursts and how it relates to the preceding outburst characteristics of amplitude and width. The data sample involved multiple IUE observations for 16 dwarf novae and 8 novae along with existing optical coverage. Results indicate that most systems show correlated ultraviolet (UV) flux behavior with interoutburst phase, with 60 percent of the dwarf novae and 50 percent of the novae having decreasing flux trends while 33 percent of the dwarf novae and 38 percent of the novae show rising UV flux during the quiescent interval. All of the dwarf novae with decreasing UV fluxes at 1475A have orbital periods longer than 4.4 hours, while all (except BV Cen) with flat or rising fluxes at 1475A have orbital periods less than two hours. There are not widespread correlations of the UV fluxes with the amplitude of the preceding outburst and no correlations with the width of the outburst. From a small sample (7) that have relatively large quiescent V magnitude changes between the IUE observations, most show a strong correlation between the UV and optical continuum. Interpretation of the results is complicated by not being able to determine how much the white dwarf contributes to the ultraviolet flux. However, it is now evident that noticeable changes are occurring in the hot zones in accreting systems long after the outburst, and not only for systems that are dominated by the white dwarf. Whether these differences are due to different outburst mechanisms or to changes on white dwarfs which provide varying contributions to the UV flux remains to be determined

A new hard X-ray source discovered by INTEGRAL: IGR J16442-554

DEFF Research Database (Denmark)

Bozzo, E.; Ferrigno, C.; Chenevez, Jérôme

2009-01-01

During a key program observation of the inner Galactic disc performed between 2009-08-30 14:04 and 2009-09-01 12:03 (UTC), a new source was discovered in the INTEGRAL/IBIS mosaic image. The best localization is RA: 251.088 DEC: -55.808, with a 90% error radius of 3.6 arcmin. The source, IGR J16442......-5548, is detected with a significance of 7 sigma in the 20-40 keV energy band and of 5 sigma in the 40-100 keV energy band. The corresponding flux is about 7 mCrab. The source is not detected in the JEM-X monitor: upper limits at 3 sigma c.l. are respectively 2 and 5 mCrab in the 3-10 keV and 10-25 keV energy bands...

INTEGRAL discovery of a new hard X-ray transient: IGR J17177-3656

DEFF Research Database (Denmark)

Frankowski, A.; Ferrigo, C.; Bozzo, E.

2011-01-01

We report on the discovery of a new transient source, IGR J17177-3656, detected during the INTEGRAL observation performed from 2011-03-15 09:23 to 2011-03-15 22:42 UT. The source was detected by IBIS/ISGRI at a significance level of 13 and 9 standard deviations, in the 20-40 keV and 40-80 ke......:56:42) (J2000) with a 90% confinement radius of 1.5 arcmin, fully consistent with the ISGRI position. The IBIS/ISGRI spectrum (20-150 keV) can be well described by a power-law with photon index 1.8+/-0.3 (chi2/dof=0.5 for 8 dof). The estimated 20-100 keV flux is 3.7e-10 erg/s/cm2. We could not detect any...

Puzzling thermonuclear burst behaviour from the transient low-mass X-ray binary IGR J17473-2721

DEFF Research Database (Denmark)

Chenevez, Jérôme

2010-01-01

We investigate the thermonuclear bursting behaviour of IGR J17473-2721, an X-ray transient that in 2008 underwent a six month long outburst, starting (unusually) with an X-ray burst. We detected a total of 57 thermonuclear bursts throughout the outburst with AGILE, Swift, RXTE, and INTEGRAL...... it dropped (at a persistent flux corresponding to 15%of m˙ Edd) a few days before the outburst peak, after which bursts were not detected for a month. As the persistent emission subsequently decreased, the bursting activity resumed at a much lower rate than during the outburst rise. This hysteresis may arise...... produced a similar quenching of burst activity....

IGR J18284-0345: a new hard X-ray transient detected by INTEGRAL

DEFF Research Database (Denmark)

Blanchard, T.; Beckmann, V.; Chenevez, Jérôme

2009-01-01

V. The intrinsic absorption is not well constrained and has been fixed to the Galactic value of NH = 5.6e21 1/cm**2. The model flux of IGR J18284-0345 is 3.5e-11 erg/cm**2/sec and 1.4e-10 erg/cm**2/sec in the 2-10 keV and 2-30 keV band, respectively. No source has been reported within the Swift/XRT error circle...... at 2009 March 20 at 15:58 UT for an effective on source time of 1.9 ksec. Swift/XRT detected one source within the INTEGRAL error circle at RA=277.125, DEC=-3.762 with an uncertainty of 4 arcsec. The spectrum can be fit together with the INTEGRAL data by a black body model with kT = 4.0±0.2 ke...

XMM-Newton Observation of IGR J18538-0102 and an Optical/IR Candidate

Science.gov (United States)

Halpern, J. P.; Gotthelf, E. V.

2010-02-01

We observed the X-ray counterpart of IGR J18538-0102 (Stephen et al., ATel #2441) in a pointed observation with XMM-Newton on 2004 October 8. This apparently steady source (in an 8 ks exposure) can be fitted with a power-law model of photon index 1.7+/-0.1, NH = (1.5+/-0.2)e22 cm-2, and unabsorbed 1-10 keV flux 5.6e-12 erg cm-2 s-1. Its coordinates 18h53m48.50s, -01d02'30.0" (J2000), with 90% confidence error radius of 3.2", coincide with an object in the 2MASS Point Source Catalog at 18h53m48.48s, -01d02'29.6" of magnitudes H=14.00+/-0.05 and K=12.50+/-0.05.

Newspaper: Files. Radiotherapy and accidental radiation protection. Scientific management between I.G.R. and I.P.S.N; Presse dossiers. Radiotherapie et radioprotection accidentelle. Partenariat scientifique entre l'IGR et l'IPSN

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-02-01

The Gustave-Roussy Institute (I.G.R.), the biggest european center of cancer treatment, and the Institute of Protection and Nuclear Safety (I.P.S.N.) that lead important researches and expertise in accidental radiation protection have established an agreement for a research program for six years. The objective is to speed up the researches in radio-pathology and radiobiology to improve the techniques used to treat the irradiated persons, for therapeutic or accidental reasons. Three principal themes have been chosen as starting point: Diagnosis and prognosis bio-indicators of irradiation effects on the digestive system, biological dosimetry and long term effects of a high dose irradiation. New themes will be tackled in function of the results or new needs. (N.C.)

XMM-Newton and NuSTAR Simultaneous X-Ray Observations of IGR J11215-5952

International Nuclear Information System (INIS)

Sidoli, L.; Tiengo, A.; Paizis, A.; Sguera, V.; Lotti, S.; Natalucci, L.

2017-01-01

We report the results of an XMM - Newton and NuSTAR coordinated observation of the Supergiant Fast X-ray Transient (SFXT) IGR J11215–5952, performed on 2016 February 14, during the expected peak of its brief outburst, which repeats every ∼165 days. Timing and spectral analysis were performed simultaneously in the energy band 0.4–78 keV. A spin period of 187.0 (±0.4) s was measured, consistent with previous observations performed in 2007. The X-ray intensity shows a large variability (more than one order of magnitude) on timescales longer than the spin period, with several luminous X-ray flares that repeat every 2–2.5 ks, some of which simultaneously observed by both satellites. The broadband (0.4–78 keV) time-averaged spectrum was well deconvolved with a double-component model (a blackbody plus a power law with a high energy cutoff) together with a weak iron line in emission at 6.4 keV (equivalent width, EW, of 40 ± 10 eV). Alternatively, a partial covering model also resulted in an adequate description of the data. The source time-averaged X-ray luminosity was 10 36 erg s −1 (0.1–100 keV; assuming 7 kpc). We discuss the results of these observations in the framework of the different models proposed to explain SFXTs, supporting a quasi-spherical settling accretion regime, although alternative possibilities (e.g., centrifugal barrier) cannot be ruled out.

XMM-Newton and NuSTAR Simultaneous X-Ray Observations of IGR J11215-5952

Energy Technology Data Exchange (ETDEWEB)

Sidoli, L.; Tiengo, A.; Paizis, A. [INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica, Via E. Bassini 15, I-20133 Milano (Italy); Sguera, V. [INAF, Istituto di Astrofisica Spaziale e Fisica Cosmica, Via Gobetti 101, I-40129 Bologna (Italy); Lotti, S.; Natalucci, L., E-mail: sidoli@iasf-milano.inaf.it [INAF, Istituto di Astrofisica e Planetologia Spaziali, Via Fosso del Cavaliere 100, I-00133 Roma (Italy)

2017-04-01

We report the results of an XMM - Newton and NuSTAR coordinated observation of the Supergiant Fast X-ray Transient (SFXT) IGR J11215–5952, performed on 2016 February 14, during the expected peak of its brief outburst, which repeats every ∼165 days. Timing and spectral analysis were performed simultaneously in the energy band 0.4–78 keV. A spin period of 187.0 (±0.4) s was measured, consistent with previous observations performed in 2007. The X-ray intensity shows a large variability (more than one order of magnitude) on timescales longer than the spin period, with several luminous X-ray flares that repeat every 2–2.5 ks, some of which simultaneously observed by both satellites. The broadband (0.4–78 keV) time-averaged spectrum was well deconvolved with a double-component model (a blackbody plus a power law with a high energy cutoff) together with a weak iron line in emission at 6.4 keV (equivalent width, EW, of 40 ± 10 eV). Alternatively, a partial covering model also resulted in an adequate description of the data. The source time-averaged X-ray luminosity was 10{sup 36} erg s{sup −1} (0.1–100 keV; assuming 7 kpc). We discuss the results of these observations in the framework of the different models proposed to explain SFXTs, supporting a quasi-spherical settling accretion regime, although alternative possibilities (e.g., centrifugal barrier) cannot be ruled out.

Hard X-ray detection of the black hole candidates 4U 1630-47 and IGR J17091-3624 up to 200 keV with INTEGRAL

DEFF Research Database (Denmark)

Bodaghee, A.; Kuulkers, E.; Tomsick, J. A.

2012-01-01

During monitoring observations of the Norma and Inner Perseus Arms (rev. 1209: 2012 Sept. 6 from 18:18:23 to 22:00:21 UTC), INTEGRAL-ISGRI revealed that the accreting black hole candidates 4U 1630-47 and IGR J17091-3624 have brightened in the hard X-rays. Mosaic images consisting of 12.6 ks worth...

The puzzling case of the accreting millisecond X-ray pulsar IGR J00291+5934: flaring optical emission during quiescence

Science.gov (United States)

Baglio, M. C.; Campana, S.; D'Avanzo, P.; Papitto, A.; Burderi, L.; Di Salvo, T.; Muñoz-Darias, T.; Rea, N.; Torres, D. F.

2017-04-01

We present an optical (gri) study during quiescence of the accreting millisecond X-ray pulsar IGR J00291+5934 performed with the 10.4 m Gran Telescopio Canarias (GTC) in August 2014. Although the source was in quiescence at the time of our observations, it showed a strong optical flaring activity, more pronounced in bluer filters (I.e. the g-band). After subtracting the flares, we tentatively recovered a sinusoidal modulation at the system orbital period in all bands, even when a significant phase shift with respect to an irradiated star, typical of accreting millisecond X-ray pulsars, was detected. We conclude that the observed flaring could be a manifestation of the presence of an accretion disc in the system. The observed light curve variability could be explained by the presence of a superhump, which might be another proof of the formation of an accretion disc. In particular, the disc at the time of our observations was probably preparing the new outburst of the source, which occurred a few months later, in 2015. Based on observations made with the Gran Telescopio Canarias (GTC), installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, in the island of La Palma.

Star-planet systems as possible progenitors of cataclysmic binaries

International Nuclear Information System (INIS)

Livio, M.; Soker, N.

1984-01-01

The evolution of a star-planet system is studied, in the phase in which the star becomes a red giant, thus enabling the planet to accrete mass either from its envelope or from its wind. It is found that for planets which are embedded in the envelope, there exists a certain critical initial mass, under which the planets are totally evaporated while spiralling-in. Planets with an initial mass above this critical value are all transformed into low-mass stellar companions to the giant's core. The final masses of these secondaries are almost independent of their initial mass and their initial separation, as long as the latter is greater than a certain critical value. The final masses are essentially determined by the giant's envelope mass. The star-planet separation is found to increase for planets that accrete from the stellar wind, when tidal effects are neglected. Possible consequences of these results on the problem of formation of low-mass cataclysmic binaries are discussed. (author)

Flickering of the symbiotic variable CH Cygni during outburst

Energy Technology Data Exchange (ETDEWEB)

Slovak, M H [Texas Univ., Austin (USA). Dept. of Astronomy; Africano, J

1978-11-01

High-speed and conventional BVRI photometry are reported for the bright symbiotic variable CH Cygni (M6 IIIe), obtained during the course of a recent outburst. Unlike the quiescent symbiotic stars, the presence of flickering similar in nature to that seen in the cataclysmic variables has been confirmed during this active phase. The BVRI photometry for a sample of stars in the field is used to derive the reddening and the distance to CH Cyg. A composite energy distribution is derived from 0.35 to 11.0 ..mu..m which clearly establishes the existence of a variable, blue continuum. The lack of variability in the near infrared suggests that the blue continuum arises from a hot companion. A binary model including a subluminous hot companion accreting material from the stellar wind of an SRa variable is discussed to account for the observed photometric properties.

IGR J17544-2619 IN DEPTH WITH SUZAKU: DIRECT EVIDENCE FOR CLUMPY WINDS IN A SUPERGIANT FAST X-RAY TRANSIENT

International Nuclear Information System (INIS)

Rampy, Rachel A.; Smith, David M.; Negueruela, Ignacio

2009-01-01

We present direct evidence for dense clumps of matter in the companion wind in a Supergiant Fast X-ray Transient (SFXT) binary. This is seen as a brief period of enhanced absorption during one of the bright, fast flares that distinguish these systems. The object under study was IGR J17544-2619, and a total of 236 ks of data were accumulated with the Japanese satellite Suzaku. The activity in this period spans a dynamic range of almost 10 4 in luminosity and gives a detailed look at SFXT behavior.

Variation of Surface Air Temperature in Relation to El Nino and Cataclysmic Volcanic Eruptions, 1796-1882

Science.gov (United States)

Wilson, Robert M.

1999-01-01

During the contemporaneous interval of 1796-1882 a number of significant decreases in temperature are found in the records of Central England and Northern Ireland. These decreases appear to be related to the occurrences of El Nino and/or cataclysmic volcanic eruptions. For example, a composite of residual temperatures of the Central England dataset, centering temperatures on the yearly onsets of 20 El Nino of moderate to stronger strength, shows that, on average, the change in temperature varied by about +/- 0.3 C from normal being warmer during the boreal fall-winter leading up to the El Nino year and cooler during the spring-summer of the El Nino year. Also, the influence of El Nino on Central England temperatures appears to last about 1-2 years. Similarly, a composite of residual temperatures of the Central England dataset, centering temperatures on the month of eruption for 26 cataclysmic volcanic eruptions, shows that, on average, the change in temperature decreased by about 0.1 - 0.2 C, typically, 1-2 years after the eruption, although for specific events, like Tambora, the decrease was considerably greater. Additionally, tropical eruptions appear to produce greater changes in temperature than extratropical eruptions, and eruptions occurring in boreal spring-summer appear to produce greater changes in temperature than those occurring in fall-winter.

INTEGRAL/JEM-X sees a flare from IGR J19112+1358 and gives a refined position

DEFF Research Database (Denmark)

Chenevez, Jérôme; Rodriguez, J.; Wilms, J.

2009-01-01

22.3s, DEC= +13d 55' 08.4" with an uncertainty of 1'. This new position is 2.4' from the suggested counterpart IRAS 19089+1351 (ATel #1489) and thus discards this IR source as possible counterpart. No source is reported within the JEM-X error box in the SIMBAD, NED, 2MASS extended source or NVSS...... catalogs. Several sources can however be found in the 2MASS point source catalog. IGR J19112+1358 was detected in the 3-10 keV JEM-X1 mosaic at 7 sigma for an effective exposure of 5.9 ks. The measured flux was 19.5 +/- 4.5 mCrab and below 8 mCrab (5-sigma upper limit) between 10-25 keV. ISGRI 20-40 keV 3...

White dwarfs in cataclysmic variables

International Nuclear Information System (INIS)

Sion, E.M.

1987-01-01

The physical properties and evolutionary state of the underlying white dwarfs in CVs are explored. Observations of 25 white dwarfs with effective temperature upper limits of 9000-75,000 K are discussed. Correlations between effective temperature, orbital period, accretion rate, and CV type with respect to the CV period gap are considered. Quasi-static and hydrodynamic evolutionary models are used to explain the surface temperature/luminosity distribution ratios. 42 references

The soft spectral state of the black hole candidate IGR J17091-3624 observed by INTEGRAL and Swift

DEFF Research Database (Denmark)

Del Santo, M.; Kuulkers, E.; Bozzo, E.

2011-01-01

The currently on-going outburst of the black hole candidate (BHC) IGR J17091-3624 (ATel #3144, #3159, #3167) has been recently observed simultaneously with INTEGRAL and Swift. The source was in the IBIS FOV on 2011 Feb. 28 from 17:45 to 21:23 (UTC; exposure time 7.7 ks) during the Galactic Bulge......, a better description of the spectrum (confirmed by the F-test) can be obtained adding a disk black-body component (red. chi^2=1.1 (302 d.o.f.)). The fit of the joint XRT+IBIS/ISGRI broad-band spectrum (0.8-200 keV) gives an absorption column density of N_H=1.00+/-0.06, a disc black-body temperature of 1...

Newspaper: Files. Radiotherapy and accidental radiation protection. Scientific management between I.G.R. and I.P.S.N

International Nuclear Information System (INIS)

1999-02-01

The Gustave-Roussy Institute (I.G.R.), the biggest european center of cancer treatment, and the Institute of Protection and Nuclear Safety (I.P.S.N.) that lead important researches and expertise in accidental radiation protection have established an agreement for a research program for six years. The objective is to speed up the researches in radio-pathology and radiobiology to improve the techniques used to treat the irradiated persons, for therapeutic or accidental reasons. Three principal themes have been chosen as starting point: Diagnosis and prognosis bio-indicators of irradiation effects on the digestive system, biological dosimetry and long term effects of a high dose irradiation. New themes will be tackled in function of the results or new needs. (N.C.)

Control of grasshoppers by combined application of Paranosema locustae and an insect growth regulator (IGR) (cascade) in rangelands in China.

Science.gov (United States)

Guo, Yanyan; An, Zhao; Shi, Wangpeng

2012-12-01

The relatively low direct mortality caused by Paranosema locustae (Canning) has limited its application for controlling grasshopper when densities are high, and this study sought to determine if the simultaneous use of this pathogen and the IGR, Flufenoxuron (Cascade) could provide effective control. Nine treatments were tested: 45% Malathion EC at 1500 ml/ha, 5% Cascade at 150 ml/ha, 5% Cascade at 75 ml/ha, 5% Cascade at 37.5 ml/ha, P. locustae at 7.5 x 10(9) spores/ha, combinations of 5% Cascade at 75 ml/ha and P. locustae at 7.5 x 10(9) spores/ha, applied in different rations (1:1, 1:2, 1:3) in the same plot, the untreated control. P. locustae was applied on nonoverlapping plots with the IGR. The different in-plot combinations of P. locustae and Cascade in different ratios provided significantly better overall control of grasshoppers (all species) than the treatment of 5% Cascade of 150 ml/ha after 5d, but combinations were not significantly different from the other concentrations of Cascade after 12 and 31 d. When results were examined separately for specific species of grasshoppers, reduction of Dasyhippus harbipes (Fischer-Waldheim), was higher than that of Myrmeleotettix palpalis (Zubovsky). While combinations showed significant differences in the infection of different grasshopper species at 5 and 12 d posttreatment, no significant differences in rate of infection among the primary species (M. palpalis, D. harbipes, and Oedaleus asiaticus Bei-Bienko) were detected 31 d posttreatment. Our study found that P. locustae by itself could control grasshopper populations at medium densities but the combined application of P. locustae and Cascade at a ratio of 1:2 was more effective against high-density grasshopper populations.

VHE gamma-rays from radio pulsars and cataclysmic variables. [PSR 1055-52; PSR 1509-58; PSR 1620-26; PSR 1747-46; PSR 1800-21; PSR 1818-04; PSR 1821-24; PSR 1822-09; PSR 1823-13; PSR 1855+09; PSR 1929+10; PSR 1957+20

Energy Technology Data Exchange (ETDEWEB)

De Jager, O.C.; Brink, C.; Meintjies, P.J.; Nel, H.I.; North, A.R.; Raubenheimer, B.C.; Van der Walt, D.J. (Potchefstroom Univ. for C.H.E. (South Africa). Dept. of Physics)

1990-03-01

We present the results of observations (above 1 TeV) of radio pulsars and cataclysmic variables with the Potchefstroom air Cerenkov facility. We were able to confirm our previous detection of PSR 1509-58 and the final significance is 1.7x10{sup -5}. A DC enhancement at the 10{sup -3} significance level was seen from the L{sub 4} Lagrange position in the PSR 1957+20 system. This result was confirmed by COS-B data. We were also able to detect the 5.4 ms pulsar PSR 1855+09 at a marginal significance level of 5%. However, the best and longest observation indicates non-uniformity at the 0.005 significance level. The TeV light curve resembles the radio light curve. The latter is also reminiscent of other millisecond pulsar observed above 1 TeV. The intermediate polar AEAQR (P = 33.08s) shows a period shift which is consistent with recent model predictions. However, the present significance of this results does not allow an unambiguous claim. (orig.).

Exploring the Hard and Soft X-ray Emission of Magnetic Cataclysmic Variables

Science.gov (United States)

de Martino, D.; Anzolin, G.; Bonnet-Bidaud, J.-M.; Falanga, M.; Matt, G.; Mouchet, M.; Mukai, K.; Masetti, N.

2009-05-01

A non-negligible fraction of galactic hard (>20 keV) X-ray sources were identified as CVs of the magnetic Intermediate Polar type in INTEGRAL, SWIFT and RXTE surveys, that suggests a still hidden but potentially important population of faint hard X-ray sources. Simbol-X has the unique potential to simultaneously characterize their variable and complex soft and hard X-ray emission thus allowing to understand their putative role in galactic populations of X-ray sources.

La mort de Tupac Amaru, l’ultime cataclysme ?

Directory of Open Access Journals (Sweden)

Nejma Jalal-Kermele

2011-06-01

Full Text Available L’exécution du jeune Inca Tupac Amaru en 1572 fut pour les Indiens du Pérou un véritable cataclysme. Il s’insérait dans un contexte particulier : celui de la vice-royauté du Pérou qui connaissait, depuis de longues années, une série de guerres et de complots. Au cœur de cet espace troublé, se trouvait un royaume néo-inca que la Couronne espérait vaincre par une politique du compromis. Toledo, envoyé pour faire rentrer le Pérou dans un ordre nouveau, avait marqué, dès le début de son gouvernement, son opposition au régime de Vilcabamba dont la seule présence fragilisait la légitimité du pouvoir du roi de Castille aux Indes. C’était donc la question des Justes Titres qui préoccupait Toledo, décidé à lutter activement contre la pensée de Las Casas. La mort d’un messager, envoyé pour négocier avec l’Inca, servit de prétexte à une attaque de Vilcabamba qui permit l’arrestation du jeune Tupac Amaru que le vice-roi décida de condamner à mort, en dépit de sa conversion au catholicisme. L’exécution marqua pour les Indiens la fin d’un monde, la fin d’un espoir et apparut comme l’ultime catastrophe, une répétition de la mort de l’Inca et des Dieux. De nombreux récits rapportent la détresse infinie des Indiens et la désapprobation quasi générale des témoins. Nous voudrions proposer ici une rapide analyse des différentes lectures du cataclysme et tenter de montrer que, pour Toledo, il s’inséra dans une politique claire et assumée. Outre la question idéologique, le vice-roi s’appuya sur des arguments sécuritaires et fit finalement de Tupac Amaru non un prince mais un simple délinquant de droit commun. Cette réécriture de l’Histoire permit d’instaurer une nouvelle définition de la politique espagnole au Pérou mais le cataclysme marqua les esprits et Tupac Amaru, loin d’être oublié, devint un symbole qui traversa les siècles jusqu’à aujourd’hui.La ejecución del joven

The interoutburst behavior of cataclysmic variables

International Nuclear Information System (INIS)

Szkody, P.; Stablein, C.; Mattei, J.A.; Waagen, E.O.

1991-01-01

Existing IUE and AAVSO archive data were used to accomplish a large scale study of what happens to the UV flux of accretion disk systems during the quiescent intervals between outbursts, and how it relates to the preceding outburst characteristics of amplitude and width. The data sample involved multiple IUE observations for 16 dwarf novae and 8 novae along with existing optical coverage. Results indicate that most systems show correlated UV flux behavior with interoutburst phase, with 60 percent of the dwarf novae and 50 percent of the novae having decreasing flux trends while 33 percent of the dwarf novae and 38 percent of the novae show rising UV flux during the quiescent interval. All of the dwarf novae with decreasing UV fluxes at 1475 A have orbital periods longer than 4.4 hours, while all (except BV Cen) with flat or rising fluxes at 1475 A have orbital periods less than two hours. From a small sample (7) that have relatively large quiescent V magnitude changes between the IUE observations, most show a strong correlation between the UV and optical continuum. Interpretation of the results is complicated by not being able to determine how much the white dwarf contributes to the ultraviolet flux. However, it is now evident that noticeable changes are occurring in the hot zones in accreting systems long after the outburst, and not only for systems that are dominated by the white dwarf. 25 refs

The Magnetospheric Boundary in Cataclysmic Variables

Directory of Open Access Journals (Sweden)

Hellier Coel

2014-01-01

During outbursts, when the accretion flow increases by orders of magnitude, the disk pushes the magnetosphere inwards, and appears to feed field lines over a much greater range of magnetic azimuth. The non-equilibrium outburst behaviour shows an even richer phenomenology than in quiescence, adding DNOs and QPOs into the mix.

Reducing the devastating effects of cataclysmic events: Cooperation

International Nuclear Information System (INIS)

Jing Ding; Fong, P.

1989-01-01

Natural calamities, including earthquakes, land sinkings, volcanos, floods, tsunamis, hurricanes, avalanches, lightnings, forest fires, are discussed. Their devastating effects can be alleviated by cooperative efforts, sometimes international, among all concerned. The successful earthquake management of the Haicheng event is discussed as an example. Now the authors have environmental calamities, including erosion floods, dam failures, acid rain, ozone depletion, and the global greenhouse effect. There are empirical and theoretical questions about whether the greenhouse effect leads to global warming or polar ice melting. The warming prediction was based on model calculation with an incorrect boundary condition. When corrected with the right boundary condition, the models predict ice melting. The same is borne out in independent static and dynamic theories. Thus, there will be no greenhouse warming, only a sea level rise of up to 200 feet, which is much worse. The only way out is replacing fossil fuels by nuclear power. The nuclear fear is analyzed in terms of the Don Quixote syndrome and Laplace dictum. The lessons of Three Mile Island and Chernobyl actually strengthen the case of nuclear safety. New reactor technology and design will make it even safer. After 250 years of studying the history of the earth, geologists are now able to show that it is nothing but a long series of gradual changes and violent events. What was true in the past will remain so in the future, and cataclysms will occur again and again. Earthquakes, land subsidence and volcanic eruptions; flood and drought; the tsunami, tropical cyclones and avalanches; lightning and forest fires; have occurred ever since mountains, oceans, rivers, atmosphere, and ice sheets have been on the earth, and they will continue to happen

Radiative Transfer Through Discs of Cataclysmic Variables

Czech Academy of Sciences Publication Activity Database

Korčáková, Daniela; Nagel, T.; Werner, K.; Suleimanov, V.; Votruba, Viktor

2010-01-01

Roč. 1273, - (2010), s. 350-353 ISSN 1551-7616. [European White Dwarf Workshop /17./. Tübingen, 16.08.2010-20.08.2010] R&D Projects: GA ČR GP205/09/P476 Institutional research plan: CEZ:AV0Z10030501 Keywords : radiative transfer * Doppler effect, * accretion disks Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

Brown dwarfs in retrogradely precessing cataclysmic variables?

Directory of Open Access Journals (Sweden)

Martin E.L.

2011-07-01

Full Text Available We compare Smoothed Particle Hydrodynamic simulations of retrogradely precessing accretion disks that have a white dwarf primary and a main sequence secondary with observational data and with theory on retrograde precession via tidal torques like those by the Moon and the Sun on the Earth [1, 2]. Assuming the primary does not accrete much of the mass lost from the secondary, we identify the theoretical low mass star/brown dwarf boundary. We find no observational candidates in our study that could qualify as brown dwarfs.

Identification of Hard X-ray Sources in Galactic Globular Clusters: Simbol-X Simulations

Science.gov (United States)

Servillat, M.

2009-05-01

Globular clusters harbour an excess of X-ray sources compared to the number of X-ray sources in the Galactic plane. It has been proposed that many of these X-ray sources are cataclysmic variables that have an intermediate magnetic field, i.e. intermediate polars, which remains to be confirmed and understood. We present here several methods to identify intermediate polars in globular clusters from multiwavelength analysis. First, we report on XMM-Newton, Chandra and HST observations of the very dense Galactic globular cluster NGC 2808. By comparing UV and X-ray properties of the cataclysmic variable candidates, the fraction of intermediate polars in this cluster can be estimated. We also present the optical spectra of two cataclysmic variables in the globular cluster M 22. The HeII (4868 Å) emission line in these spectra could be related to the presence of a magnetic field in these objects. Simulations of Simbol-X observations indicate that the angular resolution is sufficient to study X-ray sources in the core of close, less dense globular clusters, such as M 22. The sensitivity of Simbol-X in an extended energy band up to 80 keV will allow us to discriminate between hard X-ray sources (such as magnetic cataclysmic variables) and soft X-ray sources (such as chromospherically active binaries).

Rapid oscillations in cataclysmic variables. III. An oblique rotator in AE aquarii

International Nuclear Information System (INIS)

Patternson, J.

1979-01-01

A rapid, strictly periodic oscillation has been discovered in the light curve of the novalike variable AE Aquarii. The fundamental period is 33.076737 s, with comparable power at the first harmonic. The amplitude averages 0.2--0.3% but can exceed 1% in flares. Pulse timings around the binary orbit prove that the periodicity arises in the white dwarf, and lead to an accurate measurement of the projected orbital velocity. The velocity curve and other constraints lead to a mass determination for the component stars :0.74 +- 0.06 M/sub sun/ for the late-type star and 0.94 +- 0.10 M/sub sun/ for the white dwarf. Estimates are also given for the system dimensions, luminosity, distance, and mass transfer rate.Quasi-periodic oscillations are also detected in flares, and have periods near the coherent periods of 16.5 and 33 s. Their characteristics suggest an origin in gaseous blobs produced by instabilities near the inner edge of the accretion disk.A model is presented in which the strict periodicity arises from the rotation of an accreting, magnetized white dwarf, with a surface field of 10 6 --10 7 gauss. Future spectroscopic, polarimetric, and X-ray observations should provide critical tests for predictions of the model

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.

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.

THE TIME DOMAIN SPECTROSCOPIC SURVEY: VARIABLE SELECTION AND ANTICIPATED RESULTS

Energy Technology Data Exchange (ETDEWEB)

Morganson, Eric; Green, Paul J. [Harvard Smithsonian Center for Astrophysics, 60 Garden St, Cambridge, MA 02138 (United States); Anderson, Scott F.; Ruan, John J. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Myers, Adam D. [Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States); Eracleous, Michael; Brandt, William Nielsen [Department of Astronomy and Astrophysics, 525 Davey Laboratory, The Pennsylvania State University, University Park, PA 16802 (United States); Kelly, Brandon [Department of Physics, Broida Hall, University of California, Santa Barbara, CA 93106-9530 (United States); Badenes, Carlos [Department of Physics and Astronomy and Pittsburgh Particle Physics, Astrophysics and Cosmology Center (PITT PACC), University of Pittsburgh, 3941 O’Hara St, Pittsburgh, PA 15260 (United States); Bañados, Eduardo [Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany); Blanton, Michael R. [Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Bershady, Matthew A. [Department of Astronomy, University of Wisconsin, 475 N. Charter St., Madison, WI 53706 (United States); Borissova, Jura [Instituto de Física y Astronomía, Universidad de Valparaíso, Av. Gran Bretaña 1111, Playa Ancha, Casilla 5030, and Millennium Institute of Astrophysics (MAS), Santiago (Chile); Burgett, William S. [GMTO Corp, Suite 300, 251 S. Lake Ave, Pasadena, CA 91101 (United States); Chambers, Kenneth, E-mail: emorganson@cfa.harvard.edu [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States); and others

2015-06-20

We present the selection algorithm and anticipated results for the Time Domain Spectroscopic Survey (TDSS). TDSS is an Sloan Digital Sky Survey (SDSS)-IV Extended Baryon Oscillation Spectroscopic Survey (eBOSS) subproject that will provide initial identification spectra of approximately 220,000 luminosity-variable objects (variable stars and active galactic nuclei across 7500 deg{sup 2} selected from a combination of SDSS and multi-epoch Pan-STARRS1 photometry. TDSS will be the largest spectroscopic survey to explicitly target variable objects, avoiding pre-selection on the basis of colors or detailed modeling of specific variability characteristics. Kernel Density Estimate analysis of our target population performed on SDSS Stripe 82 data suggests our target sample will be 95% pure (meaning 95% of objects we select have genuine luminosity variability of a few magnitudes or more). Our final spectroscopic sample will contain roughly 135,000 quasars and 85,000 stellar variables, approximately 4000 of which will be RR Lyrae stars which may be used as outer Milky Way probes. The variability-selected quasar population has a smoother redshift distribution than a color-selected sample, and variability measurements similar to those we develop here may be used to make more uniform quasar samples in large surveys. The stellar variable targets are distributed fairly uniformly across color space, indicating that TDSS will obtain spectra for a wide variety of stellar variables including pulsating variables, stars with significant chromospheric activity, cataclysmic variables, and eclipsing binaries. TDSS will serve as a pathfinder mission to identify and characterize the multitude of variable objects that will be detected photometrically in even larger variability surveys such as Large Synoptic Survey Telescope.

Development of a Mailing List on Variable Stars, VSNET

Science.gov (United States)

Nogami, D.; Kato, T.; Baba, H.; Kunjaya, C.

Various usages of the Internet have been developed and made remarkable progress these years, which is now dramatically changing the style of astronomical study. Among those, the maing list is thought to be most useful to study of unpredictable objects for the characteristics, especially rapidness and equality. We started a mailing list (VSNET) on variable stars, mainly on cataclysmic variables and supernovae, in 1994 July for mutual exchange of information and ideas between astronomers including professionals and amateurs. Up to now, the various articles have been distributed, for example, calls for follow up observations of transient objects discovered in the UV or X-ray region, calls for ground-based observations simultaneous with ones by the space telescopes, discoveries of supernovae, alert notices of outbursts in long dormant dwarf novae (EG Cnc, AL Com, UZ Boo, HT Cas, etc), and so on. You can get long-term light curves of variable stars drawn using VSNET data on the VSNET web pages http://www.kusastro.kyoto-u.ac.jp/vsnet/. The archives of VSNET mails are available via VSNET web pages and anonymous ftp ftp://ftp.kusastro.kyoto-u.ac.jp/pub/vsnet/Mail/. If you have any questions and suggestions on VSNET, please feel free to contact us (vsnet-adm@kusastro.kyoto-u.ac.jp).

DISCOVERY OF X-RAY PULSATIONS FROM THE INTEGRAL SOURCE IGR J11014–6103

Energy Technology Data Exchange (ETDEWEB)

Halpern, J. P.; Gotthelf, E. V.; Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027 (United States); Tomsick, J. A. [Space Sciences Laboratory, 7 Gauss Way, University of California, Berkeley, CA 94720-7450 (United States); Ng, C.-Y. [Department of Physics, The University of Hong Kong, Pokfulam Road, Hong Kong (China); Bodaghee, A. [Georgia College and State University, CBX 82, Milledgeville, GA 31061 (United States); Rodriguez, J.; Chaty, S. [Laboratoire AIM (UMR-E 9005 CEA/DSM-CNRS-Université Paris Diderot), Irfu/Service d' Astrophysique, CEA-Saclay, F-91191 Gif-sur-Yvette Cedex (France); Rahoui, F., E-mail: jules@astro.columbia.edu [European Southern Observatory, Karl Schwarzschild-Strasse 2, D-85748 Garching bei München (Germany)

2014-11-10

We report the discovery of PSR J1101–6101, a 62.8 ms pulsar in IGR J11014–6103, a hard X-ray source with a jet and a cometary tail that strongly suggests it is moving away from the center of the supernova remnant (SNR) MSH 11–61A at v > 1000 km s{sup –1}. Two XMM-Newton observations were obtained with the EPIC pn in small window mode, resulting in the measurement of its spin-down luminosity E-dot =1.36×10{sup 36} erg s{sup –1}, characteristic age τ {sub c} = 116 kyr, and surface magnetic field strength B{sub s} = 7.4 × 10{sup 11} G. In comparison to τ {sub c}, the 10-30 kyr age estimated for MSH 11–61A suggests that the pulsar was born in the SNR with initial period in the range 54 ≤ P {sub 0} ≤ 60 ms. PSR J1101–6101 is the least energetic of the 15 rotation-powered pulsars detected by INTEGRAL, and has a high efficiency of hard X-ray radiation and jet power. We examine the shape of the cometary nebula in a Chandra image, which is roughly consistent with a bow shock at the velocity inferred from the SNR age and the pulsar's E-dot . However, its structure differs in detail from the classic bow shock, and we explore possible reasons for this.

Time dependence of the UV resonance lines in the cataclysmic variables SU UMa, RX And and 0623+71

International Nuclear Information System (INIS)

Woods, J.A.; Drew, J.E.; Verbunt, Frank

1990-01-01

We present IUE observations of the dwarf novae SU UMa and RX And, and of the nova-like variable 0623 + 71. At the time of observation, SU UMa and RX And were in outburst. All three systems show variability in the wind-formed UV resonance lines of N v λ 1240, Si IV λ 1397 and C IV λ 1549 on timescale of hours. The amplitude of variation is smallest in RX And and largest in 0623 + 71. There is evidence that the variations observed in SU UMa's UV spectrum repeat on the orbital period. Our observations of SU UMa also reveal variability in the continuum flux during the decline from outburst maximum that is much more marked in the UV than at optical wavelengths. (author)

Advances in astronomy and astrophysics

CERN Document Server

Kopal, Zdenek

1963-01-01

Advances in Astronomy and Astrophysics, Volume 2 brings together numerous research works on different aspects of astronomy and astrophysics. This volume is composed of six chapters and begins with a summary of observational record on twilight extensions of the Venus cusps. The next chapter deals with the common and related properties of binary stars, with emphasis on the evaluation of their cataclysmic variables. Cataclysmic variables refer to an object in one of three classes: dwarf nova, nova, or supernova. These topics are followed by discussions on the eclipse phenomena and the eclipses i

Cataclysms and Catastrophes: A Case Study of Improving K-12 Science Education Through a University Partnership

Science.gov (United States)

Fennell, T.; Ellins, K. K.; Morris, M.; Christeson, G.

2003-12-01

The K-12 science teacher is always seeking ways of improving and updating their curriculum by integrating the latest research into their most effective classroom activities. However, the daily demands of delivering instruction to large numbers of students coupled with the rapid advances in some fields of science can often overwhelm this effort. The NSF-sponsored Cataclysms and Catastrophes curriculum, developed by scientists from the The University of Texas at Austin Institute for Geophysics (UTIG) and Bureau of Economic Geology (BEG), middle and high school teachers, and UT graduate students (NSF GK-12 fellows) working together through the GK-12 program, is a textbook example of how universities can facilitate this quest, benefiting education at both K-12 and university levels. In 1992, "The Great K-T Extinction Debate" was developed as an activity in the Planet Earth class at the Liberal Arts and Science Academy of Austin as an interdisciplinary approach to science. Taking advantage of the media attention generated by the impact scenario for the K-T extinction, the activity consists of students participating in a simulated senate hearing on the potential causes of the K-T extinction and their implications for society today. This activity not only exposes students to the wide range of science involved in understanding mass extinctions, but also to the social, political and economic implications when this science is brought into the public arena and the corresponding use of data in decision making and disaster preparedness. While "The Great K-T Extinction Debate" was always a popular and effective activity with students, it was in desperate need of updating to keep pace with the evolving scientific debate over the cause of the K-T extinction and the growing body of impact evidence discovered over the past decade. By adding two inquiry-based learning activities that use real geophysical data collected by scientists studying the buried Chicxulub feature as a

Diverse Long-term Variability of Five Candidate High-mass X-Ray Binaries from Swift Burst Alert Telescope Observations

Energy Technology Data Exchange (ETDEWEB)

Corbet, Robin H. D. [University of Maryland, Baltimore County, MD 21250 (United States); Coley, Joel B. [NASA Postdoctoral Program, and Astroparticle Physics Laboratory, Code 661 NASA Goddard Space Flight Center, Greenbelt Road, MD 20771 (United States); Krimm, Hans A., E-mail: corbet@umbc.edu [Universities Space Research Association, 10211 Wincopin Circle, Suite 500, Columbia, MD 21044 (United States)

2017-09-10

We present an investigation of long-term modulation in the X-ray light curves of five little-studied candidate high-mass X-ray binaries using the Swift Burst Alert Telescope. IGR J14488-5942 and AX J1700.2-4220 show strong modulation at periods of 49.6 and 44 days, respectively, which are interpreted as orbital periods of Be star systems. For IGR J14488-5942, observations with the Swift X-ray Telescope show a hint of pulsations at 33.4 s. For AX J1700.2-4220, 54 s pulsations were previously found with XMM-Newton . Swift J1816.7-1613 exhibits complicated behavior. The strongest peak in the power spectrum is at a period near 150 days, but this conflicts with a determination of a period of 118.5 days by La Parola et al. AX J1820.5-1434 has been proposed to exhibit modulation near 54 days, but the extended BAT observations suggest modulation at slightly longer than double this at approximately 111 days. There appears to be a long-term change in the shape of the modulation near 111 days, which may explain the apparent discrepancy. The X-ray pulsar XTE J1906+090, which was previously proposed to be a Be star system with an orbital period of ∼30 days from pulse timing, shows peaks in the power spectrum at 81 and 173 days. The origins of these periods are unclear, although they might be the orbital period and a superorbital period respectively. For all five sources, the long-term variability, together with the combination of orbital and proposed pulse periods, suggests that the sources contain Be star mass donors.

Intermediate polars as low-field magnetic cataclysmic variables

International Nuclear Information System (INIS)

Wickramasinghe, D.T.; Kinwah Wu; Ferrario, Lilia

1991-01-01

We present the first detailed calculations of the polarization properties of extended accretion shocks on the surface of a magnetic white dwarf where allowance is made both for field spread and for the change in shock height as a function of specific accretion rate. These results are used to show conclusively that the null detection of circular polarization in most IPs imply fields of less than 5 MG. We suggest that the X-ray properties of MCVs depends critically on the fractional area of the white-dwarf surface over which accretion occurs, and on the type of accretion (smooth or clumpy). We argue that in the known IPs, accretion occurs via a disc. The accretion flow is smooth and a strong shock forms making them a powerful source of hard X-rays. We propose that there is a new class of MCV distinct from the IPs, where the white dwarf is asynchronous and accretes without a disc in which the accretion is clumpy and the radiation is mainly in the EUV region. (author)

Glimpse of the highly obscured HMXB IGR J16318-4848 with Hitomi

Science.gov (United States)

Hitomi Collaboration; Aharonian, Felix; Akamatsu, Hiroki; Akimoto, Fumie; Allen, Steven W.; Angelini, Lorella; Audard, Marc; Awaki, Hisamitsu; Axelsson, Magnus; Bamba, Aya; Bautz, Marshall W.; Blandford, Roger; Brenneman, Laura W.; Brown, Gregory V.; Bulbul, Esra; Cackett, Edward M.; Chernyakova, Maria; Chiao, Meng P.; Coppi, Paolo S.; Costantini, Elisa; de Plaa, Jelle; de Vries, Cor P.; den Herder, Jan-Willem; Done, Chris; Dotani, Tadayasu; Ebisawa, Ken; Eckart, Megan E.; Enoto, Teruaki; Ezoe, Yuichiro; Fabian, Andrew C.; Ferrigno, Carlo; Foster, Adam R.; Fujimoto, Ryuichi; Fukazawa, Yasushi; Furuzawa, Akihiro; Galeazzi, Massimiliano; Gallo, Luigi C.; Gandhi, Poshak; Giustini, Margherita; Goldwurm, Andrea; Gu, Liyi; Guainazzi, Matteo; Haba, Yoshito; Hagino, Kouichi; Hamaguchi, Kenji; Harrus, Ilana M.; Hatsukade, Isamu; Hayashi, Katsuhiro; Hayashi, Takayuki; Hayashida, Kiyoshi; Hiraga, Junko S.; Hornschemeier, Ann; Hoshino, Akio; Hughes, John P.; Ichinohe, Yuto; Iizuka, Ryo; Inoue, Hajime; Inoue, Yoshiyuki; Ishida, Manabu; Ishikawa, Kumi; Ishisaki, Yoshitaka; Iwai, Masachika; Kaastra, Jelle; Kallman, Tim; Kamae, Tsuneyoshi; Kataoka, Jun; Katsuda, Satoru; Kawai, Nobuyuki; Kelley, Richard L.; Kilbourne, Caroline A.; Kitaguchi, Takao; Kitamoto, Shunji; Kitayama, Tetsu; Kohmura, Takayoshi; Kokubun, Motohide; Koyama, Katsuji; Koyama, Shu; Kretschmar, Peter; Krimm, Hans A.; Kubota, Aya; Kunieda, Hideyo; Laurent, Philippe; Lee, Shiu-Hang; Leutenegger, Maurice A.; Limousin, Olivier O.; Loewenstein, Michael; Long, Knox S.; Lumb, David; Madejski, Greg; Maeda, Yoshitomo; Maier, Daniel; Makishima, Kazuo; Markevitch, Maxim; Matsumoto, Hironori; Matsushita, Kyoko; McCammon, Dan; McNamara, Brian R.; Mehdipour, Missagh; Miller, Eric D.; Miller, Jon M.; Mineshige, Shin; Mitsuda, Kazuhisa; Mitsuishi, Ikuyuki; Miyazawa, Takuya; Mizuno, Tsunefumi; Mori, Hideyuki; Mori, Koji; Mukai, Koji; Murakami, Hiroshi; Mushotzky, Richard F.; Nakagawa, Takao; Nakajima, Hiroshi; Nakamori, Takeshi; Nakashima, Shinya; Nakazawa, Kazuhiro; Nobukawa, Kumiko K.; Nobukawa, Masayoshi; Noda, Hirofumi; Odaka, Hirokazu; Ohashi, Takaya; Ohno, Masanori; Okajima, Takashi; Ota, Naomi; Ozaki, Masanobu; Paerels, Frits; Paltani, Stéphane; Petre, Robert; Pinto, Ciro; Porter, Frederick S.; Pottschmidt, Katja; Reynolds, Christopher S.; Safi-Harb, Samar; Saito, Shinya; Sakai, Kazuhiro; Sasaki, Toru; Sato, Goro; Sato, Kosuke; Sato, Rie; Sawada, Makoto; Schartel, Norbert; Serlemtsos, Peter J.; Seta, Hiromi; Shidatsu, Megumi; Simionescu, Aurora; Smith, Randall K.; Soong, Yang; Stawarz, Łukasz; Sugawara, Yasuharu; Sugita, Satoshi; Szymkowiak, Andrew; Tajima, Hiroyasu; Takahashi, Hiromitsu; Takahashi, Tadayuki; Takeda, Shiníchiro; Takei, Yoh; Tamagawa, Toru; Tamura, Takayuki; Tanaka, Takaaki; Tanaka, Yasuo; Tanaka, Yasuyuki T.; Tashiro, Makoto S.; Tawara, Yuzuru; Terada, Yukikatsu; Terashima, Yuichi; Tombesi, Francesco; Tomida, Hiroshi; Tsuboi, Yohko; Tsujimoto, Masahiro; Tsunemi, Hiroshi; Tsuru, Takeshi Go; Uchida, Hiroyuki; Uchiyama, Hideki; Uchiyama, Yasunobu; Ueda, Shutaro; Ueda, Yoshihiro; Uno, Shiníchiro; Urry, C. Megan; Ursino, Eugenio; Watanabe, Shin; Werner, Norbert; Wilkins, Dan R.; Williams, Brian J.; Yamada, Shinya; Yamaguchi, Hiroya; Yamaoka, Kazutaka; Yamasaki, Noriko Y.; Yamauchi, Makoto; Yamauchi, Shigeo; Yaqoob, Tahir; Yatsu, Yoichi; Yonetoku, Daisuke; Zhuravleva, Irina; Zoghbi, Abderahmen; Nakaniwa, Nozomi

2018-03-01

We report on a Hitomi observation of IGR J16318-4848, a high-mass X-ray binary system with an extremely strong absorption of NH ˜ 1024 cm-2. Previous X-ray studies revealed that its spectrum is dominated by strong fluorescence lines of Fe as well as continuum emission lines. For physical and geometrical insight into the nature of the reprocessing material, we utilized the high spectroscopic resolving power of the X-ray microcalorimeter (the soft X-ray spectrometer: SXS) and the wide-band sensitivity by the soft and hard X-ray imagers (SXI and HXI) aboard Hitomi. Even though the photon counts are limited due to unintended off-axis pointing, the SXS spectrum resolves Fe Kα1 and Kα2 lines and puts strong constraints on the line centroid and line width. The line width corresponds to a velocity of 160^{+300}_{-70} km s-1. This represents the most accurate, and smallest, width measurement of this line made so far from the any X-ray binary, much less than the Doppler broadening and Doppler shift expected from speeds that are characteristic of similar systems. Combined with the K-shell edge energy measured by the SXI and HXI spectra, the ionization state of Fe is estimated to be in the range of Fe I-IV. Considering the estimated ionization parameter and the distance between the X-ray source and the absorber, the density and thickness of the materials are estimated. The extraordinarily strong absorption and the absence of a Compton shoulder component have been confirmed. These characteristics suggest reprocessing materials that are distributed in a narrow solid angle or scattering, primarily by warm free electrons or neutral hydrogen. This measurement was achieved using the SXS detection of 19 photons. It provides strong motivation for follow-up observations of this and other X-ray binaries using the X-ray Astrophysics Recovery Mission and other comparable future instruments.

X-Ray Reflection and an Exceptionally Long Thermonuclear Helium Burst from IGR J17062-6143

Energy Technology Data Exchange (ETDEWEB)

Keek, L.; Strohmayer, T. E. [X-ray Astrophysics Laboratory, Astrophysics Science Division, NASA/GSFC, Greenbelt, MD 20771 (United States); Iwakiri, W.; Serino, M. [MAXI team, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Ballantyne, D. R. [Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332-0430 (United States); Zand, J. J. M. in’t, E-mail: laurens.keek@nasa.gov [SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht (Netherlands)

2017-02-10

Thermonuclear X-ray bursts from accreting neutron stars power brief but strong irradiation of their surroundings, providing a unique way to study accretion physics. We analyze MAXI /Gas Slit Camera and Swift /XRT spectra of a day-long flash observed from IGR J17062-6143 in 2015. It is a rare case of recurring bursts at a low accretion luminosity of 0.15% Eddington. Spectra from MAXI , Chandra , and NuSTAR observations taken between the 2015 burst and the previous one in 2012 are used to determine the accretion column. We find it to be consistent with the burst ignition column of 5×10{sup 10} g cm{sup −2}, which indicates that it is likely powered by burning in a deep helium layer. The burst flux is observed for over a day, and decays as a straight power law: F ∝ t {sup −1.15}. The burst and persistent spectra are well described by thermal emission from the neutron star, Comptonization of this emission in a hot optically thin medium surrounding the star, and reflection off the photoionized accretion disk. At the burst peak, the Comptonized component disappears, when the burst may dissipate the Comptonizing gas, and it returns in the burst tail. The reflection signal suggests that the inner disk is truncated at ∼10{sup 2} gravitational radii before the burst, but may move closer to the star during the burst. At the end of the burst, the flux drops below the burst cooling trend for 2 days, before returning to the pre-burst level.

OPTICAL STUDIES OF 13 HARD X-RAY SELECTED CATACLYSMIC BINARIES FROM THE SWIFT-BAT SURVEY

International Nuclear Information System (INIS)

Halpern, Jules P.; Thorstensen, John R.

2015-01-01

From a set of 13 cataclysmic binaries that were discovered in the Swift Burst Alert Telescope (BAT) survey, we conducted time-resolved optical spectroscopy and/or time-series photometry of 11, with the goal of measuring their orbital periods and searching for spin periods. Seven of the objects in this study are new optical identifications. Orbital periods are found for seven targets, ranging from 81 minutes to 20.4 hr. PBC J0706.7+0327 is an AM Herculis star (polar) based on its emission-line variations and large amplitude photometric modulation on the same period. Swift J2341.0+7645 may be a polar, although the evidence here is less secure. Coherent pulsations are detected from two objects, Swift J0503.7−2819 (975 s) and Swift J0614.0+1709 (1412 s and 1530 s, spin and beat periods, respectively), indicating that they are probable intermediate polars (DQ Herculis stars). For two other stars, longer spin periods are tentatively suggested. We also present the discovery of a 2.00 hr X-ray modulation from RX J2015.6+3711, possibly a contributor to Swift J2015.9+3715, and likely a polar

Spectroscopic study of the optical counterpart to the fast X-ray transient IGR J17544-2619 based on observations at the 1.5-m RTT-150 telescope

Science.gov (United States)

Bikmaev, I. F.; Nikolaeva, E. A.; Shimansky, V. V.; Galeev, A. I.; Zhuchkov, R. Ya.; Irtuganov, E. N.; Melnikov, S. S.; Sakhibullin, N. A.; Grebenev, S. A.; Sharipova, L. M.

2017-10-01

We present the results of our long-term photometric and spectroscopic observations at the Russian-Turkish RTT-150 telescope for the optical counterpart to one of the best-known sources, representatives of the class of fast X-ray transients, IGR J17544-2619. Based on our optical data, we have determined for the first time the orbital and physical parameters of the binary system by the methods of Doppler spectroscopy.We have calculated theoretical spectra of the optical counterpart by applying non- LTE corrections for selected lines and obtained the parameters of the stellar atmosphere ( T eff = 33 000 K, log g = 3.85, R = 9.5 R ⊙, and M = 23 M ⊙). The latter suggest that the optical star is not a supergiant as has been thought previously.

Linking optical and infrared observations with gravitational wave sources through transient variability

International Nuclear Information System (INIS)

Stubbs, C W

2008-01-01

Optical and infrared observations have thus far detected more celestial cataclysms than have been seen in gravity waves (GW). This argues that we should search for gravity wave signatures that correspond to transient variables seen at optical wavelengths, at precisely known positions. There is an unknown time delay between the optical and gravitational transient, but knowing the source location precisely specifies the corresponding time delays across the gravitational antenna network as a function of the GW-to-optical arrival time difference. Optical searches should detect virtually all supernovae that are plausible gravitational radiation sources. The transient optical signature expected from merging compact objects is not as well understood, but there are good reasons to expect detectable transient optical/IR emission from most of these sources as well. The next generation of deep wide-field surveys (for example PanSTARRS and LSST) will be sensitive to subtle optical variability, but we need to fill the 'blind spots' that exist in the galactic plane, and for optically bright transient sources. In particular, a galactic plane variability survey at λ∼ 2 μm seems worthwhile. Science would benefit from closer coordination between the various optical survey projects and the gravity wave community

A visible and infrared study of the eclipsing dwarf nova OY Carinae

International Nuclear Information System (INIS)

Berriman, G.

1984-01-01

This paper presents four visible light curves of the highly inclined, short-period cataclysmic binary star OY Carinae in quiescence. These light curves show that the red dwarf eclipses both its white dwarf companion and the accretion disc and hotspot, which originate from material transferred from the red dwarf to the white dwarf. The consequences of the findings are discussed in the light of current ideas about the evolution of cataclysmic variable stars. (author)

The spectrum and variability of radio emission from AE Aquarii

Science.gov (United States)

Abada-Simon, Meil; Lecacheux, Alain; Bastian, Tim S.; Bookbinder, Jay A.; Dulk, George A.

1993-01-01

The first detections of the magnetic cataclysmic variable AE Aquarii at millimeter wavelengths are reported. AE Aqr was detected at wavelengths of 3.4 and 1.25 mm. These data are used to show that the time-averaged spectrum is generally well fitted by a power law S(nu) varies as nu exp alpha, where alpha is approximately equal to 0.35-0.60, and that the power law extends to millimeter wavelengths, i.e., the spectral turnover is at a frequency higher than 240 GHz. It is suggested that the spectrum is consistent with that expected from a superposition of flarelike events where the frequency distribution of the initial flux density is a power law f (S0) varies as S0 exp -epsilon, with index epsilon approximately equal to 1.8. Within the context of this model, the high turnover frequency of the radio spectrum implies magnetic field strengths in excess of 250 G in the source.

Discovery of a new bona fide luminous blue variable in Norma

Science.gov (United States)

Gvaramadze, V. V.; Kniazev, A. Y.; Berdnikov, L. N.

2015-12-01

We report the results of optical spectroscopy of the candidate evolved massive star MN44 revealed via detection of a circular shell with the Spitzer Space Telescope. First spectra taken in 2009 May-June showed the Balmer lines in emission as well as numerous emission lines of iron, which is typical of luminous blue variables (LBVs) near the visual maximum. New observations carried out in 2015 May-September detected significant changes in the spectrum, indicating that the star became hotter. We found that these changes are accompanied by significant brightness variability of MN44. In particular, the Ic-band brightness decreased by ≈ 1.6 mag during the last six years and after reaching its minimum in 2015 June has started to increase. Using archival data, we also found that the Ic-band brightness increased by ≈3 mag in ≈30 yr preceding our observations. MN44 therefore represents the 17th known example of the Galactic bona fide LBVs. We detected a nitrogen-rich knot to the north-west of the star, which might represent an interstellar cloudlet interacting with the circumstellar shell. We discuss a possible association between MN44 and the INTEGRAL transient source of hard X-ray emission IGR J16327-4940, implying that MN44 might be either a colliding-wind binary or a high-mass X-ray binary.

Doppler Tomography

Science.gov (United States)

Marsh, T. R.

I review the method of Doppler tomography which translates binary-star line profiles taken at a series of orbital phases into a distribution of emission over the binary. I begin with a discussion of the basic principles behind Doppler tomography, including a comparison of the relative merits of maximum entropy regularisation versus filtered back-projection for implementing the inversion. Following this I discuss the issue of noise in Doppler images and possible methods for coping with it. Then I move on to look at the results of Doppler Tomography applied to cataclysmic variable stars. Outstanding successes to date are the discovery of two-arm spiral shocks in cataclysmic variable accretion discs and the probing of the stream/magnetospheric interaction in magnetic cataclysmic variable stars. Doppler tomography has also told us much about the stream/disc interaction in non-magnetic systems and the irradiation of the secondary star in all systems. The latter indirectly reveals such effects as shadowing by the accretion disc or stream. I discuss all of these and finish with some musings on possible future directions for the method. At the end I include a tabulation of Doppler maps published in refereed journals.

NuSTAR Discovery of a Cyclotron Line in the Accreting X-Ray Pulsar IGR J16393-4643

Science.gov (United States)

Bodaghee, Arash; Tomsick, John A.; Fornasini, Francesca M.; Krivonos, Roman; Stern, Daniel; Mori, Kaya; Rahoui, Farid; Boggs, Steven E.; Christensen, Finn E.; Craig, William W.;

[Prevalence of diabetes and impaired glucose regulation in Chengdu populations and associated dietary risk factors].

Science.gov (United States)

Dai, Hua; Chen, Li-Yu; Li, Shuang-Qing

2014-01-01

To determine the prevalence of type 2 DM and impaired glucose regulation (IGR) in Chengdu populations and to identify dietary risk factors associated with DM and IGR. Two communities in Chengdu were selected for this study. Fasting blood-glucose (FBG) and 2-hour post-meal blood glucose (2 hGlu) tests were performed in the community residents. The participants were asked to complete a questionair recording their daily food intaking. The total calorie of food, percentage of different kinds of food, and intake of electrolyte, vietamine and micro minerals were calculated and compared between those with and without type 2 DM or IGR. Of the study participants, 18.59% had type 2 DM and 24.22% had IGR. Those with DM had higher levels of intake of calorie,fat,protein and sodium, and lower levels of intake of cellulose, carbohydrates, Iron, zinc, selenium,manganese and vietamine C and E compared with those without DM/IGR (P vitamine C and E compared with those without DM/IGR (P Vitamine E was identified as a protective factor of type 2 DM (OR = 0.733) and IGR (OR = 0.990). Chengdu has a higher than national average prevalence of type 2 DM and IGR. The high percentage of dietary fat and low levels of Vitamine E are major risk factors of type 2 DM and IGR.

INVESTIGATING THE OPTICAL COUNTERPART CANDIDATES OF FOUR INTEGRAL SOURCES LOCALIZED WITH CHANDRA

International Nuclear Information System (INIS)

Özbey Arabacı, Mehtap; Kalemci, Emrah; Tomsick, John A.; Bodaghee, Arash; Halpern, Jules; Chaty, Sylvain; Rodriguez, Jerome; Rahoui, Farid

2012-01-01

We report on the optical spectroscopic follow-up observations of the candidate counterparts to four INTEGRAL sources: IGR J04069+5042, IGR J06552–1146, IGR J21188+4901, and IGR J22014+6034. The candidate counterparts were determined with Chandra, and the optical observations were performed with 1.5 m RTT-150 telescope (TÜBİTAK National Observatory, Antalya, Turkey) and 2.4 m Hiltner Telescope (MDM Observatory, Kitt Peak, Arizona). Our spectroscopic results show that one of the two candidates of IGR J04069+5042 and the one observed for IGR J06552–1146 could be active late-type stars in RS CVn systems. However, according to the likelihood analysis based on Chandra and INTEGRAL, two optically weaker sources in the INTEGRAL error circle of IGR J06552–1146 have higher probabilities to be the actual counterpart. The candidate counterparts of IGR J21188+4901 are classified as an active M-type star and a late-type star. Among the optical spectra of four candidates of IGR J22014+6034, two show Hα emission lines, one is a late-type star, and the other is an M type. The likelihood analysis favors a candidate with no distinguishing features in the optical spectrum. Two of the candidates classified as M-type dwarfs, are similar to some IGR candidates claimed to be symbiotic stars. However, some of the prominent features of symbiotic systems are missing in our spectra, and their NIR colors are not consistent with those expected for giants. We consider the IR colors of all IGR candidates claimed to be symbiotic systems and find that low-resolution optical spectrum may not be enough for conclusive identification.

NICER Discovers the Ultracompact Orbit of the Accreting Millisecond Pulsar IGR J17062–6143

Science.gov (United States)

Strohmayer, T. E.; Arzoumanian, Z.; Bogdanov, S.; Bult, P. M.; Chakrabarty, D.; Enoto, T.; Gendreau, K. C.; Guillot, S.; Harding, A. K.; Ho, W. C. G.; Homan, J.; Jaisawal, G. K.; Keek, L.; Kerr, M.; Mahmoodifar, S.; Markwardt, C. B.; Ransom, S. M.; Ray, P. S.; Remillard, R.; Wolff, M. T.

2018-05-01

We present results of recent Neutron Star Interior Composition Explorer (NICER) observations of the accreting millisecond X-ray pulsar (AMXP) IGR J17062‑6143 that show that it resides in a circular, ultracompact binary with a 38-minute orbital period. NICER observed the source for ≈26 ks over a 5.3-day span in 2017 August, and again for 14 and 11 ks in 2017 October and November, respectively. A power spectral analysis of the August exposure confirms the previous detection of pulsations at 163.656 Hz in Rossi X-ray Timing Explorer (RXTE) data, and reveals phase modulation due to orbital motion of the neutron star. A coherent search for the orbital solution using the Z 2 method finds a best-fitting circular orbit with a period of 2278.21 s (37.97 minutes), a projected semimajor axis of 0.00390 lt-s, and a barycentric pulsar frequency of 163.6561105 Hz. This is currently the shortest known orbital period for an AMXP. The mass function is 9.12 × 10‑8 M ⊙, presently the smallest known for a stellar binary. The minimum donor mass ranges from ≈0.005 to 0.007 M ⊙ for a neutron star mass from 1.2 to 2 M ⊙. Assuming mass transfer is driven by gravitational radiation, we find donor mass and binary inclination bounds of 0.0175–0.0155 M ⊙ and 19° < i < 27.°5, where the lower and upper bounds correspond to 1.4 and 2 M ⊙ neutron stars, respectively. Folding the data accounting for the orbital modulation reveals a sinusoidal profile with fractional amplitude 2.04 ± 0.11% (0.3–3.2 keV).

Relationship of classical novae to other eruptive variables

International Nuclear Information System (INIS)

Vogt, N.

1989-01-01

Classical novae are characterized by their well known large-amplitude outbursts, accompanied by the ejection of a shell. The same stars, however, apparently pass through much longer quiescent phases whose duration exceeds that of the outburst phase by a factor ∼ 10 5 and that of historical nova records by a factor 10 2 -10 3 . Therefore a large number of variable stars should exist which actually are classical nova systems but whose last outbursts occurred in prehistoric times. We assume that some of these stars are hidden among the so-called 'nova-lies' in the literature. However some eruptive variables and symbiotic stars, i.e. stars which certainly are not nova remnants, are mentioned. Variables related to classical novae can be divided into three main classes: (i) Potential novae which are possibly classical novae in their quiescent state. Potential novae must share the basic configuration and parameters (orbital period, masses) with classical novae; they must be semi-detached cataclysmic binaries with a white dwarf as primary and a Roche-lobe-filling red dwarf on, or near, the mainsequence as secondary. (ii) Stars which share some outburst characteristics with classical novae without having the same binary configuration. For example recurrent novae with giant secondaries, very slow novae (and symbiotic binary stars). (iii) Stars which are evolutionarily related to classical novae, i.e. which possibly are progenitors or successors of novae in their secular evolution, such as binary nuclei of planetary nebulae and close, but detached, white dwarf-red dwarf pairs (e.g. V 471 Tau), both resulting from common-envelope evolution. These three main groups of nova-related stars are discussed. (author)

The R band light curves of eclipses of U Gem in outburst

Czech Academy of Sciences Publication Activity Database

Šimon, Vojtěch

č. 5453 (2003), s. 1-4 ISSN 0374-0676 Institutional research plan: CEZ:AV0Z1003909 Keywords : cataclysmic variables * general binaries stars Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

The January 2015 outburst of a red nova in M31

Czech Academy of Sciences Publication Activity Database

Kurtenkov, A.A.; Pessev, P.; Tomov, T.; Barsukova, E.A.; Fabrika, S.; Vida, K.; Hornoch, Kamil; Ovcharov, E.P.; Goranskij, V.P.; Valeev, A.F.; Molnár, L.; Sárneczky, K.; Kostov, A.; Nedialkov, P.; Valenti, S.; Geier, S.; Wiersema, K.; Henze, M.; Shafter, A.W.; Dimitrova, R.V.M.; Popov, V.N.; Stritzinger, M.

2015-01-01

Roč. 578, June (2015), L10/1-L10/5 ISSN 0004-6361 Institutional support: RVO:67985815 Keywords : novae * cataclysmic variables Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.378, year: 2014

Modeling the optical radiation of the precataclysmic variable SDSS J212531-010745

Science.gov (United States)

Shimansky, V. V.; Borisov, N. V.; Nurtdinova, D. N.; Solovyeva, Yu. N.; Sakhibullin, N. A.; Spiridonova, O. I.

2015-03-01

Optical observations are analyzed to derive a set of basic parameters for the precataclysmic variable star SDSS J212531-010745, whose primary is a PG1159-type star. Spectroscopic and multiband photometric observations of the star were performed in 2008-2011 with the 6-m telescope and the Zeiss-1000 telescope of the Special Astrophysical Observatory. The shape of the binary's orbital light curves is nearly sinusoidal, with the amplitude increasing with wavelength from Δ m = 0.40 m in the B band to Δ m = 0.73 m in the R band. The spectra contain absorption lines of HeII and neutral atoms, along with HI, HeI, CII, MgII, FeII emission lines, whose intensity increases synchronously with the brightness of the system. The optical radiation from SDSS J212531-010745 has a composite nature, corresponding to a model for a pre-cataclysmic variable with strong reflection effects. Cross-correlation techniques are used to measure the radial velocities and derive the component masses. Numerical modeling of the binary's light curves, radial velocities, and spectra is performed, and a complete set of parameters determined. Considerable abundance anomalies (to 1 dex) were detected for the secondary. The primary's characteristics correspond to the evolutionary predictions for DAO dwarfs with masses M ≈ 0.5 M ⊙, and the secondary's characteristics to low-mass, main-sequence stars with the solar metallicity.

Time variability of X-ray binaries: observations with INTEGRAL. Modeling

International Nuclear Information System (INIS)

Cabanac, Clement

2007-01-01

The exact origin of the observed X and Gamma ray variability in X-ray binaries is still an open debate in high energy astrophysics. Among others, these objects are showing aperiodic and quasi-periodic luminosity variations on timescales as small as the millisecond. This erratic behavior must put constraints on the proposed emission processes occurring in the vicinity of the neutrons star or the stellar mass black-hole held by these objects. We propose here to study their behavior following 3 different ways: first we examine the evolution of a particular X-ray source discovered by INTEGRAL, IGR J19140+0951. Using timing and spectral data given by different instruments, we show that the source type is plausibly consistent with a High Mass X-ray Binary hosting a neutrons star. Subsequently, we propose a new method dedicated to the study of timing data coming from coded mask aperture instruments. Using it on INTEGRAL/ISGRI real data, we detect the presence of periodic and quasi-periodic features in some pulsars and micro-quasars at energies as high as a hundred keV. Finally, we suggest a model designed to describe the low frequency variability of X-ray binaries in their hardest state. This model is based on thermal comptonization of soft photons by a warm corona in which a pressure wave is propagating in cylindrical geometry. By computing both numerical simulations and analytical solution, we show that this model should be suitable to describe some of the typical features observed in X-ray binaries power spectra in their hard state and their evolution such as aperiodic noise and low frequency quasi-periodic oscillations. (author) [fr

The influence of IS1301 in the capsule biosynthesis locus on meningococcal carriage and disease.

Directory of Open Access Journals (Sweden)

Elisabeth Kugelberg

2010-02-01

Full Text Available Previously we have shown that insertion of IS1301 in the sia/ctr intergenic region (IGR of serogroup C Neisseria meningitidis (MenC isolates from Spain confers increased resistance against complement-mediated killing. Here we investigate the significance of IS1301 in the same location in N. meningitidis isolates from the UK. PCR and sequencing was used to screen a collection of more than 1500 meningococcal carriage and disease isolates from the UK for the presence of IS1301 in the IGR. IS1301 was not identified in the IGR among vaccine failure strains but was frequently found in serogroup B isolates (MenB from clonal complex 269 (cc269. Almost all IS1301 insertions in cc269 were associated with novel polymorphisms, and did not change capsule expression or resistance to human complement. After excluding sequence types (STs distant from the central genotype within cc269, there was no significant difference for the presence of IS1301 in the IGR of carriage isolates compared to disease isolates. Isolates with insertion of IS1301 in the IGR are not responsible for MenC disease in UK vaccine failures. Novel polymorphisms associated with IS1301 in the IGR of UK MenB isolates do not lead to the resistance phenotype seen for IS1301 in the IGR of MenC isolates.

Anupama, Prof. Gadiyara Chakrapani

Indian Academy of Sciences (India)

Specialization: Time Domain Astronomy, Cataclysmic Variables, Supernovae, Gamma-Ray Burst Sources, Active Galactic Nuclei Address: Senior Professor, Indian Institute of Astrophysics, Sarjapur Road, Koramangala, Bengaluru 560 034, Karnataka Contact: Office: (080) 2254 1344. Residence: (080) 6697 3104

The Nova Rate in NGC 2403

Czech Academy of Sciences Publication Activity Database

Franck, J.R.; Shafter, A.W.; Hornoch, Kamil; Misselt, K.A.

2012-01-01

Roč. 760, č. 1 (2012), 13-1-13-8 ISSN 0004-637X Institutional support: RVO:67985815 Keywords : galaxy NGC 2403 * cataclysmic variables Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 6.733, year: 2012

Chromospheric activity of periodic variable stars (including eclipsing binaries) observed in DR2 LAMOST stellar spectral survey

Science.gov (United States)

Zhang, Liyun; Lu, Hongpeng; Han, Xianming L.; Jiang, Linyan; Li, Zhongmu; Zhang, Yong; Hou, Yonghui; Wang, Yuefei; Cao, Zihuang

2018-05-01

The LAMOST spectral survey provides a rich databases for studying stellar spectroscopic properties and chromospheric activity. We cross-matched a total of 105,287 periodic variable stars from several photometric surveys and databases (CSS, LINEAR, Kepler, a recently updated eclipsing star catalogue, ASAS, NSVS, some part of SuperWASP survey, variable stars from the Tsinghua University-NAOC Transient Survey, and other objects from some new references) with four million stellar spectra published in the LAMOST data release 2 (DR2). We found 15,955 spectra for 11,469 stars (including 5398 eclipsing binaries). We calculated their equivalent widths (EWs) of their Hα, Hβ, Hγ, Hδ and Caii H lines. Using the Hα line EW, we found 447 spectra with emission above continuum for a total of 316 stars (178 eclipsing binaries). We identified 86 active stars (including 44 eclipsing binaries) with repeated LAMOST spectra. A total of 68 stars (including 34 eclipsing binaries) show chromospheric activity variability. We also found LAMOST spectra of 12 cataclysmic variables, five of which show chromospheric activity variability. We also made photometric follow-up studies of three short period targets (DY CVn, HAT-192-0001481, and LAMOST J164933.24+141255.0) using the Xinglong 60-cm telescope and the SARA 90-cm and 1-m telescopes, and obtained new BVRI CCD light curves. We analyzed these light curves and obtained orbital and starspot parameters. We detected the first flare event with a huge brightness increase of more than about 1.5 magnitudes in R filter in LAMOST J164933.24+141255.0.

The intermediate polar GK Persei: An unstable relation of the X-ray and the optical intensities in a series of outbursts

Czech Academy of Sciences Publication Activity Database

Šimon, Vojtěch

2015-01-01

Roč. 575, March (2015), A65/1-A65/8 ISSN 0004-6361 Institutional support: RVO:67985815 Keywords : accretion disks * radiation mechanisms * cataclysmic variables Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.378, year: 2014

Effectiveness of two insect growth regulators against Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) and Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) and their impact on population densities of arthropod predators in cotton in Pakistan.

Science.gov (United States)

Gogi, Muhammad D; Sarfraz, Rana M; Dosdall, Lloyd M; Arif, Muhammad J; Keddie, Andrew B; Ashfaq, Muhammad

2006-10-01

Field efficacies of two insect growth regulators (IGRs) at two recommended application rates, buprofezin at 370 and 555 g AI ha(-1) and lufenuron at 37 and 49 g AI ha(-1), were determined against the sweet potato whitefly, Bemisia tabaci (Gennadius), and the cotton bollworm, Helicoverpa armigera (Hübner), in experimental plots of cotton at the Directorate of Cotton Research, Faisalabad, Pakistan. Adverse effects of the IGRs on populations of associated arthropod predators, namely geocorids, chrysopids, coccinellids, formicids and arachnids, were also assessed. Both IGRs significantly reduced populations of B. tabaci at each application rate 24, 48 and 72 h after treatment, and higher doses were more effective than lower doses. Buprofezin was not effective against H. armigera at any tested dose for any time of treatment in any spray. Lufenuron applied at 37 and 49 g AI ha(-1) effectively suppressed H. armigera populations, resulting in significant reductions in crop damage. At lower doses, both IGRs appeared safe to predator populations, which did not differ significantly in IGR-treated versus untreated control plots. Population densities of formicids and coccinellids were significantly lower at high concentrations of both IGRs in treatment plots, possibly as a result of reduced prey availability. The potential role of buprofezin and lufenuron for control of B. tabaci and H. armigera in a spray programme and the likelihood of direct toxic effects of IGRs on predatory fauna of cotton are discussed.

Recurrent Novae in M31

Czech Academy of Sciences Publication Activity Database

Shafter, A.W.; Henze, M.; Rector, T. A.; Schweizer, F.; Hornoch, Kamil; Orio, M.; Pietsch, W.; Darnley, M.J.; Williams, S.C.; Bode, M.F.; Bryan, J.

2015-01-01

Roč. 216, č. 2 (2015), 34/1-34/35 ISSN 0067-0049 Institutional support: RVO:67985815 Keywords : individual (M31) galaxies * stellar content * cataclysmic variables Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 11.257, year: 2015

M31N 2008-12a - The Remarkable Recurrent Nova in M31: Panchromatic Observations of the 2015 Eruption

Czech Academy of Sciences Publication Activity Database

Darnley, M.J.; Henze, M.; Bode, M.F.; Haciusu, I.; Hernanz, M.; Hornoch, Kamil; Hounsell, R.; Kato, M.; Ness, J.-U.; Osborne, J.P.

2016-01-01

Roč. 833, č. 2 (2016), 149/1-149/38 ISSN 0004-637X Institutional support: RVO:67985815 Keywords : individual galaxies * novae cataclysmic variables * individual stars Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.533, year: 2016

A remarkable recurrent nova in M31: Discovery and optical/UV observations of the predicted 2014 eruption

Czech Academy of Sciences Publication Activity Database

Darnley, M.J.; Henze, M.; Steele, I.A.; Bode, M.F.; Ribeiro, V.A.R.M.; Rodriguez-Gil, P.; Shafter, A.W.; Williams, S.C.; Baer, D.; Hachisu, I.; Hernanz, M.; Hornoch, Kamil; Hounsell, R.A.; Kato, M.; Kiyota, S.; Kučáková, Hana; Maehara, H.; Ness, J.-U.; Piascik, A.S.; Sala, G.; Skillen, I.; Smith, R. J.; Wolf, M.

2015-01-01

Roč. 580, August (2015), A45/1-A45/23 ISSN 0004-6361 Institutional support: RVO:67985815 Keywords : individual (M31) galaxies * novae * cataclysmic variables Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.378, year: 2014

Supersoft X-rays reveal a classical nova in the M 31 globular cluster Bol 126

Czech Academy of Sciences Publication Activity Database

Henze, M.; Pietsch, W.; Haberl, F.; Della Valle, M.; Riffeser, A.; Salla, G.; Hatzidimitriou, D.; Hofmann, F.; Hartmann, D.H.; Koppenhoefer, J.; Seitz, S.; Williams, G.; Hornoch, Kamil; Itagaki, K.; Kabashima, F.; Nishiyama, K.; Xing, G.; Lee, C.H.; Magnier, E.; Chambers, K.

2013-01-01

Roč. 549, January (2013), A120/1-A120/15 ISSN 0004-6361 Institutional support: RVO:67985815 Keywords : galaxies individual M 31 * novae * cataclysmic variables Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.479, year: 2013

The relation between the long-term X-ray and optical activity of the polar AM Her (RX J1816.2+4952)

Czech Academy of Sciences Publication Activity Database

Šimon, Vojtěch

2011-01-01

Roč. 16, č. 6 (2011), s. 405-411 ISSN 1384-1076 Institutional research plan: CEZ:AV0Z10030501 Keywords : radiation mechanisms * cataclysmic variables * X-rays Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 1.411, year: 2011

Multicolour photometry and spectroscopy 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.

2006-01-01

Roč. 6, č. 1 (2006), s. 137-142 ISSN 1009-9271 Institutional research plan: CEZ:AV0Z10030501 Keywords : cataclysmic variables * circumstellar matter * stars: novae Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 0.746, year: 2006

A Spectroscopic and Photometric Survey of Novae in M31

Czech Academy of Sciences Publication Activity Database

Shafter, A.W.; Darnley, M.J.; Hornoch, Kamil; Filippenko, A.V.; Bode, M.F.; Ciardullo, R.; Misselt, K.A.; Hounsell, R.A.; Chornock, R.; Matheson, T.

2011-01-01

Roč. 734, č. 1 (2011), 12/1-12/28 ISSN 0004-637X Institutional research plan: CEZ:AV0Z10030501 Keywords : individual galaxy (M31) * cataclysmic variables Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 6.024, year: 2011

Journal of Astrophysics and Astronomy | Indian Academy of Sciences

Indian Academy of Sciences (India)

2016-01-27

14 a cataclysmic variable, PG 1336-018 a binary with an sdB pulsator and finally HR 1217 a roAp star. The paper concludes with what the limitations are in our observations and how we can overcome them in the future.

New Fellows and Honorary Fellow

Indian Academy of Sciences (India)

Date of birth: 19 June 1952. Specialization: X-ray Instrumentation for Astronomy, Active Galactic Nuclei and Cataclysmic Variables, Stellar Coronae, Hot Interstellar & Intracluster Media and Supernova Remnants Address: 28A, Bank Colony, Patiala 147 001, Panjab Contact: Mobile: 90048 38965. Email: kulinderpal@gmail.

The spectroscopic evolution of the symbiotic-like recurrent nova V407 Cygni during its 2010 outburst II. The circumstellar environment and the aftermath

Czech Academy of Sciences Publication Activity Database

Shore, S. N.; Wahlgren, G.M.; Augusteijn, T.; Liimets, T.; Koubský, Pavel; Šlechta, Miroslav; Votruba, Viktor

2012-01-01

Roč. 540, April (2012), A55/1-A55/15 ISSN 0004-6361 Institutional support: RVO:67985815 Keywords : gamma-ray burst * cataclysmic variables stars * star V407 Cygni Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.084, year: 2012

High-velocity winds from a dwarf nova during outburst

Science.gov (United States)

Cordova, F. A.; Mason, K. O.

1982-01-01

An ultraviolet spectrum of the dwarf nova TW Vir during an optical outburst shows shortward-shifted absorption features with edge velocities as high as 4800 km/s, about the escape velocity of a white dwarf. A comparison of this spectrum with the UV spectra of other cataclysmic variables suggests that mass loss is evident only for systems with relatively high luminosities (more than about 10 solar luminosities) and low inclination angles with respect to the observer's line of sight. The mass loss rate for cataclysmic variables is of order 10 to the -11th solar mass per yr; this is from 0.01 to 0.001 of the mass accretion rate onto the compact star in the binary. The mass loss may occur by a mechanism similar to that invoked for early-type stars, i.e., radiation absorbed in the lines accelerates the accreting gas to the high velocities observed.

Inflows, Outflows, and a Giant Donor in the Remarkable Recurrent Nova M31N 2008-12a?-Hubble Space Telescope Photometry of the 2015 Eruption

Czech Academy of Sciences Publication Activity Database

Darnley, M.J.; Hounsell, R.; Godon, M.; Perley, D.A.; Henze, M.; Kuindersma, S.; Williams, B. F.; Williams, S.C.; Bode, M.F.; Harman, D. J.; Hornoch, Kamil; Link, M.; Ness, J.-U.; Ribeiro, V.A.R.M.; Sion, E. M.; Shafter, A.W.; Shara, M. M.

2017-01-01

Roč. 849, č. 2 (2017), 96/1-96/17 ISSN 0004-637X Institutional support: RVO:67985815 Keywords : accretion * accretion disks * cataclysmic variables Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 5.533, year: 2016

Interacting binaries

CERN Document Server

Shore, S N; van den Heuvel, EPJ

1994-01-01

This volume contains lecture notes presented at the 22nd Advanced Course of the Swiss Society for Astrophysics and Astronomy. The contributors deal with symbiotic stars, cataclysmic variables, massive binaries and X-ray binaries, in an attempt to provide a better understanding of stellar evolution.

Dicty_cDB: VHQ354 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available rlkiitskrnrclk*ihqky*igr*it*rgrkeskin*rdsft*n lfhlkrkiksktfinh*rsfn*ikitnftkfy*yvnlifr*ffkfcl*q******ctkii n...t*r *psl*rlysls*rg*rlkiitskrnrclk*ihqky*igr*it*rgrkeskin*rdsft*n lfhlkrkiksktfinh*rsfn*ikitnftkfy*yvnlifr*ff

A remarkable recurrent nova in M 31: The optical observations

Czech Academy of Sciences Publication Activity Database

Darnley, M.J.; Williams, S.C.; Bode, M.F.; Henze, M.; Ness, J.-U.; Shafter, A.W.; Hornoch, Kamil; Votruba, Viktor

2014-01-01

Roč. 563, March (2014), L9/1-L9/4 ISSN 0004-6361 R&D Projects: GA MŠk LG12001 Institutional support: RVO:67985815 Keywords : galaxies: individual: M 31 * novae * cataclysmic variables Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.378, year: 2014

Evolution of the optical and hard X-ray activity of AM Her in a season dominated by the high states

Czech Academy of Sciences Publication Activity Database

Šimon, Vojtěch

2016-01-01

Roč. 361, č. 7 (2016), 235/1-235/8 ISSN 0004-640X Grant - others:GAO(CZ) GC13-39464J Institutional support: RVO:67985815 Keywords : X-rays binaries * cataclysmic variables * radiation mechanisms Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 1.622, year: 2016

Dicty_cDB: SHK664 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available *r*psl*rlysls*rg*rlkiitskrnrclk*ihqky*igr*it* rgrkeskin*rdsft*nlfhlkrkiksktfinh*rsfn*ikitnftkfy*yvnlifr*ff k...QI**ccy *tkigsn*ryh**ft*r*psl*rlysls*rg*rlkiitskrnrclk*ihqky*igr*it* rgrkeskin*rdsft*nlfhlkrkiksktfinh*rsfn*

Dicty_cDB: VSH111 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available tskrnrclk*ihqk y*igr*it*rgrkeskin*rdsft*nlfhlkrkiksktfinh*rsfn*ikitnftkfy*y vnlifrvvlsssaynnnnnnnyvpk*lifkkl...nklkn**i*kk--- ---ksti**ccy*tkigsn*ryh**ft*r*psl*rlysls*rg*rlkiitskrnrclk*i hqky*igr*it*rgrkeskin*rdsft*nlfh

Observations of TT Ari requested in support of MOST observations

Science.gov (United States)

Waagen, Elizabeth O.

2012-08-01

Dr. Nikolaus Vogt (Universidad de Valparaiso, Chile) requested simultaneous photometry and spectroscopy of the novalike (VY Scl subtype) cataclysmic variable TT Ari in support of upcoming observations with the Canadian Microvariability and Oscillations of Stars (MOST) satellite 2012 September 13 through October 20. The Departamento de Fisica y Astronomia of the Valparaiso University will carry out photometry with small telescopes in central Chile but the assistance of other observers, particularly in other latitudes and longitudes, is requested. The observations are being carried out to study superhump behavior, which is still not well understood despite the amount of research done in all classes of cataclysmic variables. TT Ari exibits superhumps - both positive (the superhump period is longer than the orbital period) and negative (the superhump period is shorter than the orbital period). While positive superhumps are thought probably to be the result of an eccentric configuration in the accretion disk, the mechanism for negative superhumps is not yet understood except that it may be related to the disk's being warped out of the orbital plane, leading to complex torque phenomena. TT Ari, one of the brightest cataclysmic variables, exhibits occasional fadings of several magnitudes, from its usual high-state (maximum) magnitude of ~10.5V to a low-state magnitude as faint as 16V. These fadings occur every 20-25 years, and last between 500 and 1000 days. According to observations in the AAVSO International Database, TT Ari is currently magnitude 10.5V. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details, particularly regarding goals of the campaign, and observing instructions.

On the SW Sex-type eclipsing cataclysmic variable SDSS0756+0858

Energy Technology Data Exchange (ETDEWEB)

Tovmassian, Gagik; Hernandez, Mercedes Stephania; González-Buitrago, Diego; Zharikov, Sergey; García-Díaz, Maria Teresa, E-mail: gag@astro.unam.mx [Instituto de Astronomía, Universidad Nacional Autonoma de México, Apdo. Postal 877, Ensenada, Baja California 22800 (Mexico)

2014-03-01

We conducted a spectroscopic and photometric study of SDSS J075653.11+085831. X-ray observations were also attempted. We determined the orbital period of this binary system to be 3.29 hr. It is a deep eclipsing system, whose spectra show mostly single-peaked, Balmer emission lines and a rather intense He II line. There is also the presence of faint (often double-peaked) He I emission lines as well as several absorption lines, Mg I being the most prominent. All of these features point toward the affiliation of this object with the growing number of SW Sex-type objects. We developed a phenomenological model of an SW Sex system to reproduce the observed photometric and spectral features.

On the SW Sex-type eclipsing cataclysmic variable SDSS0756+0858

International Nuclear Information System (INIS)

Tovmassian, Gagik; Hernandez, Mercedes Stephania; González-Buitrago, Diego; Zharikov, Sergey; García-Díaz, Maria Teresa

2014-01-01

We conducted a spectroscopic and photometric study of SDSS J075653.11+085831. X-ray observations were also attempted. We determined the orbital period of this binary system to be 3.29 hr. It is a deep eclipsing system, whose spectra show mostly single-peaked, Balmer emission lines and a rather intense He II line. There is also the presence of faint (often double-peaked) He I emission lines as well as several absorption lines, Mg I being the most prominent. All of these features point toward the affiliation of this object with the growing number of SW Sex-type objects. We developed a phenomenological model of an SW Sex system to reproduce the observed photometric and spectral features.

Rapid oscillations in cataclysmic variables. VI. Periodicities in erupting dwarf novae

International Nuclear Information System (INIS)

Patterson, J.

1981-01-01

We report an extensive study of the coherent oscillations observed in high-speed photometry of dwarf novae during eruption. The oscillations are in all cases singly periodic and sinusoidal to the limits of measurement. The detection of oscillations in 14 separate eruptions of AH Her and SY Cnc enables a general study of period variations. The stars trace out characteristic loops (''banana diagrams'') in the period-intensity plane. New detections are also reported for SS Cyg, EM Cyg, and HT Cas

Mass loss from interacting close binary systems

Science.gov (United States)

Plavec, M. J.

1981-01-01

The three well-defined classes of evolved binary systems that show evidence of present and/or past mass loss are the cataclysmic variables, the Algols, and Wolf-Rayet stars. It is thought that the transformation of supergiant binary systems into the very short-period cataclysmic variables must have been a complex process. The new evidence that has recently been obtained from the far ultraviolet spectra that a certain subclass of the Algols (the Serpentids) are undergoing fairly rapid evolution is discussed. It is thought probable that the remarkable mass outflow observed in them is connected with a strong wind powered by accretion. The origin of the circumbinary clouds or flat disks that probably surround many strongly interacting binaries is not clear. Attention is also given to binary systems with hot white dwarf or subdwarf components, such as the symbiotic objects and the BQ stars; it is noted that in them both components may be prone to an enhanced stellar wind.

X-ray and optical observations of the ultrashort period dwarf nova SW Ursae Majoris - A likely new DQ Herculis star

Science.gov (United States)

Shafter, A. W.; Szkody, P.; Thorstensen, J. R.

1986-01-01

Time-resolved X-ray and optical photometric and optical spectroscopic observations of the ultrashort period cataclysmic variable SW UMa are reported. The spectroscopic observations reveal the presence of an s-wave component which is almost in phase with the extreme line wings and presumably the white dwarf. This very unusual phasing in conjunction with the available optical and X-ray data seems to indicate that a region of enhanced emission exists on the opposite side of the disk from the expected location of the hot spot. The photometric observations reveal the presence of a hump in the light curve occurring at an orbital phase which is consistent with the phase at which the region of enhanced line emission is most favorably seen. Changes in the hump amplitude are seen from night to night, and a 15.9 min periodicity is evident in the light curve. The optical and X-ray periodicities suggest that SW UMa is a member of the DQ Her class of cataclysmic variables.

Late Pleistocene-Holocene cataclysmic eruptions at Nevado de Toluca and Jocotitlan volcanoes, central Mexico

Science.gov (United States)

Macias, J.L.; Garcia, P.A.; Arce, J.L.; Siebe, C.; Espindola, J.M.; Komorowski, J.C.; Scott, K.

1997-01-01

This field guide describes a five day trip to examine deposits of Late Pleistocene-Holocene cataclysmic eruptions at Nevado de Toluca and Jocotitlan volcanoes in central Mexico. We will discuss the stratigraphy, petrology, and sedimentological characteristics of these deposits which provide insights into the eruptive history, type of volcanic activity, and transport and emplacement mechanisms of pyroclastic materials. These parameters will allow us to discuss the kinds of hazards and the risk that they pose to populations around these volcanoes. The area to be visited is tectonically complex thus we will also discuss the location of the volcanoes with respect to the tectonic environment. The first four days of the field trip will be dedicated to Nevado de Toluca Volcano (19 degrees 09'N; 99 degrees 45'W) located at 23 km. southwest of the City of Toluca, and is the fourth highest peak in the country, reaching an elevation of 4,680 meters above sea level (m.a.s.l.). Nevado de Toluca is an andesitic-dacitic stratovolcano, composed of a central vent excavated upon the remains of older craters destroyed by former events. Bloomfield and Valastro, (1974, 1977) concluded that the last cycle of activity occurred nearly equal 11,600 yr. ago. For this reason Nevado de Toluca has been considered an extinct volcano. Our studies, however, indicate that Nevado de Toluca has had at least two episodes of cone destruction by sector collapse as well as several explosive episodes including plinian eruptions and dome-destruction events. These eruptions occurred during the Pleistocene but a very young eruption characterized by surge and ash flows occurred ca. 3,300 yr. BP. This new knowledge of the volcano's eruptive history makes the evaluation of its present state of activity and the geological hazards necessary. This is important because the area is densely populated and large cities such as Toluca and Mexico are located in its proximity.

[Comparative study on oral candidal infection in individuals with diabetes mellitus and impaired glucose regulation].

Science.gov (United States)

Huang, Jing-hua; Liu, Yang; Liu, Hong-wei

2012-06-01

To investigate the positive rate, infection rate and bearing rate of salivary candida in patients with type 2 diabetes mellitus (DM), individuals with impaired glucose regulation (IGR) and individuals with normal glucose tolerance (NGT) and their predisposing factors. Questionnaire was given to 145 patients with DM, 142 individuals with IGR and 149 NGT individuals. Oral examination was carried out, and fasting plasma glucose (FPG) level and plasma glucose level of 2 hours post glucose-load (PG2h), resting salivary flow, salivary pH value were tested. Salivary candida was cultured. In DM, IGR and NGT groups, the positive rates of salivary candida were 21.4% (31/145), 7.0% (10/142), 4.7% (7/149) respectively, the infection rates were 7.6% (11/145), 1.4% (2/142), 1.3% (2/149) respectively, and the bearing rates of salivary candida were 13.8% (20/145), 5.6% (8/142), 3.4% (5/149) respectively. The candida positive rate, candida infection rate in DM group were higher than those of IGR and NGT groups respectively (P 0.05). Resting salivary flow in DM [(1.30 ± 1.20) ml/10 min] and IGR [(1.40 ± 1.17) ml/10 min]groups were lower than that in NGT group [(1.93 ± 1.66) ml/10 min], salivary pH values in DM (7.11 ± 0.56) and IGR (7.05 ± 0.48) groups were lower than that in NGT group (7.38 ± 0.48) (P salivary candida was influenced to some degree by age, FPG level and bearing denture (OR value = 1.106, 1.258, 3.166). The patients with DM were more subjected to bearing or infection of candida than individuals with IGR and NGT. To control the plasma glucose level will help to decrease the positive rate and infection rate of oral candida.

Diabetes and pre-diabetes are associated with cardiovascular risk factors and carotid/femoral intima-media thickness independently of markers of insulin resistance and adiposity

Directory of Open Access Journals (Sweden)

Paccaud Fred

2007-10-01

Full Text Available Abstract Background Impaired glucose regulation (IGR is associated with detrimental cardiovascular outcomes such as cardiovascular disease risk factors (CVD risk factors or intima-media thickness (IMT. Our aim was to examine whether these associations are mediated by body mass index (BMI, waist circumference (waist or fasting serum insulin (insulin in a population in the African region. Methods Major CVD risk factors (systolic blood pressure, smoking, LDL-cholesterol, HDL-cholesterol, were measured in a random sample of adults aged 25–64 in the Seychelles (n = 1255, participation rate: 80.2%. According to the criteria of the American Diabetes Association, IGR was divided in four ordered categories: 1 normal fasting glucose (NFG, 2 impaired fasting glucose (IFG and normal glucose tolerance (IFG/NGT, 3 IFG and impaired glucose tolerance (IFG/IGT, and 4 diabetes mellitus (DM. Carotid and femoral IMT was assessed by ultrasound (n = 496. Results Age-adjusted levels of the major CVD risk factors worsened gradually across IGR categories (NFG Conclusion We found graded relationships between IGR categories and both major CVD risk factors and carotid/femoral IMT. These relationships were only partly accounted for by BMI, waist and insulin. This suggests that increased CVD-risk associated with IGR is also mediated by factors other than the considered markers of adiposity and insulin resistance. The results also imply that IGR and associated major CVD risk factors should be systematically screened and appropriately managed.

The spectroscopic evolution of the symbiotic-like recurrent nova V407 Cygni during its 2010 outburst

Czech Academy of Sciences Publication Activity Database

Shore, S. N.; Wahlgren, G.M.; Augusteijn, T.; Liimets, T.; Page, K.L.; Osborne, J.P.; Beardmore, A.P.; Koubský, Pavel; Šlechta, Miroslav; Votruba, Viktor

2011-01-01

Roč. 527, March (2011), A98/1-A98/15 ISSN 0004-6361 Grant - others:EU(XE) ESA PECS project No 98058. Institutional research plan: CEZ:AV0Z10030501 Keywords : novae * cataclysmic variables Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 4.587, year: 2011

General Relativity Theory Explains the Shnoll Effect and Makes Possible Forecasting Earthquakes and Weather Cataclysms (Letters to Progress in Physics

Directory of Open Access Journals (Sweden)

Rabounski D.

2014-04-01

Full Text Available The Shnoll effect manifests itself in the fine structure of the noise registered in very sta- ble processes, where the magnitude of signal and the average noise remain unchanged. It is found in the periodic fluctuation of the fine structure of the noise according to the cosmic cycles connected with stars, the Sun, and the Moon. Th e Shnoll effect is ex- plained herein, employing the framework of General Relativity, as the twin / entangled synchronization states of the observer’s reference frame. The states are repeated while the observer travels, in common with the Earth, through the c osmic grid of the geodesic synchronization paths that connect his local reference fra me with the reference frames of other cosmic bodies. These synchronization periods matc h the periods that are man- ifested due to the Shnoll e ff ect, regardless of which process produces the noise. These synchronization periods are expected to exist in the noise o f natural processes of any type (physics, biology, social, etc. as well as in such arti ficial processes as computer- software random-number generation. This conclusion accor ds with what was registered according the Shnoll effect. The theory not only explains the Shnoll effect but also al- lows for forecasting fluctuations in the stock exchange mark et, fluctuations of weather, earthquakes, and other cataclysms.

Perinatal depression and DNA methylation of oxytocin-related genes: a study of mothers and their children.

Science.gov (United States)

King, Leonora; Robins, Stephanie; Chen, Gang; Yerko, Volodymyr; Zhou, Yi; Nagy, Corina; Feeley, Nancy; Gold, Ian; Hayton, Barbara; Turecki, Gustavo; Zelkowitz, Phyllis

2017-11-01

The present study investigated the association of perinatal depression (PD) with differential methylation of 3 genomic regions among mother and child dyads: exon 3 within the oxytocin receptor (OXTR) gene and 2 intergenic regions (IGR) between the oxytocin (OXT) and vasopressin (AVP) genes. Maternal PD was assessed at 5 time-points during pregnancy and postpartum. Four groups were established based on Edinburgh Postnatal Depression Scale (EPDS) cut-off scores: no PD, prenatal or postpartum depressive symptoms only and persistent PD (depressive symptoms both prenatally and postpartum). Salivary DNA was collected from mothers and children at the final time-point, 2.9years postpartum. Mothers with persistent PD had significantly higher overall OXTR methylation than the other groups and this pattern extended to 16/22 individual CpG sites. For the IGR, only the region closer to the AVP gene (AVP IGR) showed significant differential methylation, with the persistent PD group displaying the lowest levels of methylation overall, but not for individual CpG sites. These results suggest that transient episodes of depression may not be associated with OXTR hypermethylation. Validation studies need to confirm the downstream biological effects of AVP IGR hypomethylation as it relates to persistent PD. Differential methylation of the OXTR and IGR regions was not observed among children exposed to maternal PD. The consequences of OXTR hypermethylation and AVP IGR hypomethylation found in mothers with persistent PDS may not only impact the OXT system, but may also compromise maternal behavior, potentially resulting in negative outcomes for the developing child. Copyright © 2017 Elsevier Inc. All rights reserved.

Vpliv osebnosti na vedenje pri igranju računalniških iger

OpenAIRE

Grudina, Rok

2017-01-01

Razvoj računalnikov je od konca 20. in na začetku 21. stoletja strmo narasel. Računalnike danes uporabljamo na vseh področjih. Mladostniki jih največkrat uporabljajo med preživljanjem prostega časa za igranje računalniških iger. Tako kot računalniki so se tudi računalniške igre skozi čas razvijale, da bi zadovoljile potrebe najbolj zahtevnih uporabnikov. Tako lahko danes vsak dobi igro po svojem okusu. Igre, ki so grafično izjemne, igre z zanimivo zgodbo in izzivi. Omogočajo vživetje v virtua...

Switch from cap- to factorless IRES-dependent 0 and +1 frame translation during cellular stress and dicistrovirus infection.

Directory of Open Access Journals (Sweden)

Qing S Wang

Full Text Available Internal ribosome entry sites (IRES are utilized by a subset of cellular and viral mRNAs to initiate translation during cellular stress and virus infection when canonical cap-dependent translation is compromised. The intergenic region (IGR IRES of the Dicistroviridae uses a streamlined mechanism in which it can directly recruit the ribosome in the absence of initiation factors and initiates translation using a non-AUG codon. A subset of IGR IRESs including that from the honey bee viruses can also direct translation of an overlapping +1 frame gene. In this study, we systematically examined cellular conditions that lead to IGR IRES-mediated 0 and +1 frame translation in Drosophila S2 cells. Towards this, a novel bicistronic reporter that exploits the 2A "stop-go" peptide was developed to allow the detection of IRES-mediated translation in vivo. Both 0 and +1 frame translation by the IGR IRES are stimulated under a number of cellular stresses and in S2 cells infected by cricket paralysis virus, demonstrating a switch from cap-dependent to IRES-dependent translation. The regulation of the IGR IRES mechanism ensures that both 0 frame viral structural proteins and +1 frame ORFx protein are optimally expressed during virus infection.

Cytotoxic effect of essential oil of thyme (Thymus broussonettii on the IGR-OV1 tumor cells resistant to chemotherapy

Directory of Open Access Journals (Sweden)

L. Ait M'Barek

2007-11-01

Full Text Available The anti-tumor effect of the Moroccan endemic thyme (Thymus broussonettii essential oil (EOT was investigated in vitro using the human ovarian adenocarcinoma IGR-OV1 parental cell line OV1/P and its chemoresistant counterparts OV1/adriamycin (OV1/ADR, OV1/vincristine (OV1/VCR, and OV1/cisplatin (OV1/CDDP. All of these cell lines elicited various degrees of sensitivity to the cytotoxic effect of EOT. The IC50 values (mean ± SEM, v/v were 0.40 ± 0.02, 0.39 ± 0.02, 0.94 ± 0.05, and 0.65 ± 0.03% for OV1/P, OV1/ADR, OV1/VCR, and OV1/CDDP, respectively. Using the DBA-2/P815 (H2d mouse model, tumors were developed by subcutaneous grafting of tumor fragments of similar size obtained from P815 (murin mastocytoma cell line injected in donor mouse. Interestingly, intra-tumoral injection of EOT significantly reduced solid tumor development. Indeed, by the 30th day of repeated EOT treatment, the tumor volumes of the animals were 2.00 ± 0.27, 1.35 ± 0.20, and 0.85 ± 0.18 cm³ after injection with 10, 30, or 50 µL per 72 h (six times, respectively, as opposed to 3.88 ± 0.50 cm³ for the control animals. This tumoricidal effect was associated with a marked decrease of mouse mortality. In fact, in these groups of mice, the recorded mortality by the 30th day of treatment was 30 ± 4, 18 ± 4, and 8 ± 3%, respectively, while the control animals showed 75 ± 10% of mortality. These data indicate that the EOT which contains carvacrol as the major component has an important in vitro cytotoxic activity against tumor cells resistant to chemotherapy as well as a significant antitumor effect in mice. However, our data do not distinguish between carvacrol and the other components of EOT as the active factor.

Long-term activity of QU Car

Czech Academy of Sciences Publication Activity Database

Šimon, Vojtěch

2017-01-01

Roč. 338, č. 6 (2017), s. 696-699 ISSN 0004-6337 Grant - others:GA ČR(CZ) GA13-33324S Institutional support: RVO:67985815 Keywords : novae * cataclysmic variables * accretion disks Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Astronomy (including astrophysics,space science) Impact factor: 0.916, year: 2016

Photometry of the three eclipsing novalike variables EC 21178-5417, GS Pav and V345 Pav

Science.gov (United States)

Bruch, Albert

2017-10-01

As part of a project to better characterize comparatively bright, yet little studied cataclysmic variables time resolved photometry of the three eclipsing novalike variables EC 21178-5417, GS Pav und V345 Pav is presented. Previously known orbital periods are significantly improved and long-term ephemeris are derived. Variations of eclipse profiles, occurring on time scales of days to weeks, are analyzed. Out of eclipse the light curves are characterized by low scale flickering superposed on more gradual variations with amplitudes limited to a few tenths of a magnitude and profiles which at least in EC 21178-5417 and GS Pav roughly follow the same pattern in all observed cycles. Additionally, signs for variations on the time scale of some tens of minutes are seen in GS Pav, most clearly in two subsequent nights when in the first of these a signal with a period of 15.7 min was observed over several hours. In the second night variations with twice this period were seen. While no additional insight could be gained on quasi periodic oscillations (QPOs) and dwarf nova oscillations in EC 21178-5417, previously detected by Warner et al. (2003), and while such oscillations could not be found in V345 Pav, stacked power spectra of GS Pav clearly reveal the presence of QPOs over time intervals of several hours with periods varying between 200 s and 500 s in that system.

New stars for old

International Nuclear Information System (INIS)

Henbest, N.

1980-01-01

Observations of novas made through the ages, the identity of the close double stars which make up these cataclysmic variables and the physics of nova explosions, are discussed. A picture is outlined which explains novas, dwarf novas and recurrent novas and provides a basis for interpreting the latest so called x-ray novas. (U.K.)

The BINSYN Program Package

Directory of Open Access Journals (Sweden)

Albert P. Linnell

2012-06-01

Full Text Available The BINSYN program package, recently expanded to calculate synthetic spectra of cataclysmic variables, is being further extended to include synthetic photometry of ordinary binary stars in addition to binary stars with optically thick accretion disks. The package includes a capability for differentials correction optimization of eclipsing binary systems using synthetic photometry.

YY Sex: a Polar Candidate

Science.gov (United States)

Gabdeev, M. M.; Shimanskiy, V. V.; Borisov, N. V.; Tazieva, Z. R.

2017-06-01

We present spectroscopic investigations of a cataclysmic variable star, YY Sex. There are some uncertainties in the classification of this object. We calculate Doppler maps for Hβ and HeII λ4686Å and show that there is no sign of disk accretion in YY Sex. Consequently, we conclude that YY Sex is a polar.

Quality assurance procedure for functional performance of industrial gamma radiography exposure devices

International Nuclear Information System (INIS)

Kannan, R.; Yadav, R.K.; Rajoo Kumar; Bhatt, B.C.; Sivaraman, G.; Nandkumar, A.N.

2003-05-01

An Industrial Gamma Radiography Exposure Device (IGRED) consists of various moving parts and accessories and wear and tear take place often. This may increase the possibility of radiation incidents and result in avoidable radiation exposure. Quality assurance tests of the equipment for functional performance plays a major role in ensuring that the exposure device and its accessories perform their intended functions and satisfy radiation safety requirements to avert potential exposures to operators. Therefore, in India it is practiced as mandatory requirement that each IGRED is tested for its functional performance and only after ascertaining that features of operational safety are satisfactory, loading of the source into the radiography exposure device can be permitted. This procedure which is being. practiced since the late 1970s, has contributed significantly towards the safe use of IGREDs and minimising the occurrence of radiation accidents. The purpose of this document is to highlight the importance of periodic functional performance check of each IGRED as per the checklist for the testing procedures. It is also proposed to entrust this activity to accredited laboratories, which have the necessary infrastructure to carry out this activity. The prerequisites for accreditation of such laboratories to carry out this activity and the testing procedures to be adopted for checking the functional performance of various models of IGREDs used in this country are given in this report. (author)

How Does Biological Belief in Race Relate to Our Feelings towards In-Group and Out-Groups?: A Cognitive Dissonance Framework

Science.gov (United States)

Tawa, John; Kim, Grace S.

2011-01-01

This study considered the effect of belief in race as a biological construct (RACEBIO) and inter-group anxiety (IGA) on in-group racial salience (IGRS) and out-group discomfort (OGD). Participants included 66 racially and ethnically diverse high school boarding students. As hypothesized, RACEBIO was positively related to both IGRS and OGD. In…

Workshop on The Golden Age of Cataclysmic Variables and Related Objects - II .

Directory of Open Access Journals (Sweden)

Editorial, Foreword

2015-02-01

Full Text Available Organizing Institutions:INAF – Istituto di Astrofisica e Planetologia Spaziali, Roma – INAF-IAPS, Roma, ItalyINTA – Dpt. de Cargas Utiles y Ciencias del Espacio, INTA-DCUCE, Madrid, SpainCzech Republic Academy of Sciences – Astronomical Institute, ASCR-AI, Ondřejov, Czech RepublicCzech Technical University, CTU in Prague, Czech RepublicDepartment of Physics, Technion, Haifa, IsraelRussian Academy of Sciences – Institute of Astronomy, RAS-IA, Moscow, RussiaINAF - Osservatorio Astronomico di Capodimonte, INAF-OAC, Napoli, ItalyDepartment of Astronomy, University of Washington, Seattle, WA, USA

Lominous binary supersoft X-ray sources: optical colors and absolute magnitudes

Czech Academy of Sciences Publication Activity Database

Šimon, Vojtěch

2003-01-01

Roč. 406, č. 2 (2003), s. 613-621 ISSN 0004-6361 R&D Projects: GA AV ČR KSK1048102; GA ČR GA205/00/P013 Institutional research plan: CEZ:AV0Z1003909 Keywords : close star binaries * circumstellar matter * cataclysmic variables Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.843, year: 2003

The dance of the double stars

International Nuclear Information System (INIS)

Theokas, A.

1985-01-01

The paper concerns pairs of stars orbiting one another. The evolutionary path model for close binary stars, involving a mass transfer of gases between the stars, is described. The life history of a single star; cataclysmic variables; the algol paradox, matter and lagranges' point; x-ray binaries and bursters; and pulsars; are all briefly discussed. (U.K.)

The classical nova outburst

International Nuclear Information System (INIS)

Starrfield, S.G.

1988-01-01

The classical nova outburst occurs on the white dwarf component in a close binary system. Nova systems are members of the general class of cataclysmic variables and other members of the class are the Dwarf Novae, AM Her variables, Intermediate Polars, Recurrent Novae, and some of the Symbiotic variables. Although multiwavelength observations have already provided important information about all of these systems, in this review I will concentrate on the outbursts of the classical and recurrent novae and refer to other members of the class only when necessary. 140 refs., 1 tab

Effects of Three Insect Growth Regulators on Encarsia formosa (Hymenoptera: Aphelinidae), an Endoparasitoid of Bemisia tabaci (Hemiptera: Aleyrodidae).

Science.gov (United States)

Wang, Q L; Liu, T-X

2016-12-01

Insect growth regulators (IGRs) disrupt the normal activity of the endocrine or hormone system of insects, affecting the development, reproduction, or metamorphosis of the target insects, and normally causing less detrimental effects to beneficial insects. The effects of three IGRs (pyriproxyfen, fenoxycarb, and buprofezin) on Encarsia formosa Gahan, an endoparasitoid of whiteflies, were determined using B. tabaci as a host. We assessed the effects of the IGRs on parasitoid's larval development, pupation, emergence, and contact effects of the dry residues on plant leaf and glass vial surface on adult mortality and parasitism. When the three IGRs were applied at larval stage, no or few larvae pupated in the pyriproxyfen treatments and the highest concentration of fenoxycarb, and a majority of larvae pupated in the buprofezin treatments; of those pupated, 62.3-88.1% became adults. When the IGRs were applied at the pupal stage, 2.3-17.5% developed to adults in the pyriproxyfen treatments, 59.7-89.0% in the fenoxycarb treatments, and 58.4-83.6% in the buprofezin treatments. The leaf residues of the IGRs had no appreciable effects on adults, whereas the residues on glass vial caused significantly lower adult survival than on plant leaves. The residues of pyriproxyfen and fenoxycarb slightly reduced parasitism as compared with buprofezin and controls. However, the rates of parasitoids that became adults were significantly lower, especially in the pyriproxyfen treatments. According to the standards of International Organization of Biological Control (IOBC), pyriproxyfen was harmful, while fenoxycarb and buprofezin were slightly or moderately harmful to larvae and harmless to E. formosa pupae. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

IMPACT OF MARKET-DETERMINED EXCHANGE RATES ON RICE PRODUCTION AND IMPORT IN NIGERIA

Directory of Open Access Journals (Sweden)

Aliyu Aishat Ammani

2013-10-01

Full Text Available Rice is an economically important food security crop, cultivated in almost all of Nigeria’s 36 States. Nigeria spends more than 356 billion naira (2.24 billion US dollars annually on rice import. This paper set out to analyze the trend in rice production, productivity, import, value of import and consumption that follows the adoption of the Structural Adjustment Programme (SAP in Nigeria, with emphasis on the effects of exchange rate (ER deregulation on domestic rice production and rice imports over the period 1986-2010. Relevant time series data were collected and used. A semi-log growth rate model and 2simple linear regression models were developed and estimated. Highlights of the findings include (i accelerated rate of growth in rice production (Instantaneous Growth Rate (IGR 2.2%; Cumulative Growth Rate (CGR 2.2%; rice hectarage (IGR 3.7%; CGR 3.8%; rice importation (IGR 8.5%; CGR8.9%; expenditure on rice importation (IGR 10.6%; CGR 11.2% and rice consumption (IGR 3.4%; CGR 3.5% alongside a significant deceleration in rice yield (IGR -1.4%; CGR -201.4% (ii The observed significant increase in domestic rice production cannot be confidently attributed to ER deregulation alone because it does not lead to a decrease in rice importation into Nigeria. (iii The significant increase in domestic rice importation as observed contradicts a priori expectation that ER deregulation will lead to significant decrease in rice importation. The study concluded that free market approach alone cannot stimulate local agricultural production in countries where farmers producing under low-technology-agriculture are put in direct competition with farmers from advancedtechnology-agriculture; hence governments need to restrict importation to protect local producers.

Image-guided recording system for spatial and temporal mapping of neuronal activities in brain slice.

Science.gov (United States)

Choi, Geonho; Lee, Jeonghyeon; Kim, Hyeongeun; Jang, Jaemyung; Im, Changkyun; Jeon, Nooli; Jung, Woonggyu

2018-03-01

In this study, we introduce the novel image-guided recording system (IGRS) for efficient interpretation of neuronal activities in the brain slice. IGRS is designed to combine microelectrode array (MEA) and optical coherence tomography at the customized upright microscope. It allows to record multi-site neuronal signals and image of the volumetric brain anatomy in a single body configuration. For convenient interconnection between a brain image and neuronal signals, we developed the automatic mapping protocol that enables us to project acquired neuronal signals on a brain image. To evaluate the performance of IGRS, hippocampal signals of the brain slice were monitored, and corresponding with two-dimensional neuronal maps were successfully reconstructed. Our results indicated that IGRS and mapping protocol can provide the intuitive information regarding long-term and multi-sites neuronal signals. In particular, the temporal and spatial mapping capability of neuronal signals would be a very promising tool to observe and analyze the massive neuronal activity and connectivity in MEA-based electrophysiological studies. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

ASAS-SN Discovery of a Possible Galactic Nova ASASSN-18ix

Science.gov (United States)

Stanek, K. Z.; Kochanek, C. S.; Shields, J. V.; Thompson, T. A.; Chomiuk, L.; Strader, J.; Shappee, B. J.; Holoien, T. W.-S.; Prieto, J. L.; Dong, Subo; Stritzinger, M.

2018-04-01

During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN, Shappee et al. 2014), using data from multiple ASAS-SN telescopes, we detect a new bright transient source, possibly a classical nova, but it might also be a young, large amplitude outburst of a cataclysmic variable Object RA (J2000) DEC (J2000) Gal l (deg) Gal b (deg) Disc.

ENIGMATIC RECURRENT PULSATIONAL VARIABILITY OF THE ACCRETING WHITE DWARF EQ LYN (SDSS J074531.92+453829.6)

Energy Technology Data Exchange (ETDEWEB)

Mukadam, Anjum S.; Szkody, Paula [Department of Astronomy, University of Washington, Seattle, WA 98195-1580 (United States); Townsley, D. M.; Brockett, T. [Department of Physics and Astronomy, University of Alabama, Tuscaloosa, AL 35487 (United States); Gaensicke, B. T.; Parsons, S. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Southworth, J. [Astrophysics Group, Keele University, Staffordshire ST5 5BG (United Kingdom); Hermes, J. J.; Montgomery, M. H.; Winget, D. E.; Harrold, S. [Department of Astronomy, University of Texas at Austin, Austin, TX 78759 (United States); Tovmassian, G.; Zharikov, S. [Observatorio Astronomico Nacional SPM, Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, Ensenada, BC (Mexico); Drake, A. J. [Department of Astronomy and the Center for Advanced Computing Research, California Institute of Technology, Pasadena, CA 91225 (United States); Henden, A. [American Association of Variable Star Observers, 25 Birch Street, Cambridge, MA 02138 (United States); Rodriguez-Gil, P. [Departamento de Astrofisica, Universidad de La Laguna, La Laguna, E-38204 Santa Cruz de Tenerife (Spain); Sion, E. M. [Department of Astronomy and Astrophysics, Villanova University, Villanova, PA 19085 (United States); Zola, S.; Szymanski, T. [Astronomical Observatory, Jagiellonian University, ul. Orla 171, PL-30-244 Krakow (Poland); Pavlenko, E. [Crimean Astrophysical Observatory, Crimea 98409 (Ukraine); and others

2013-09-15

Photometric observations of the cataclysmic variable EQ Lyn (SDSS J074531.92+453829.6), acquired from 2005 October to 2006 January, revealed high-amplitude variability in the range 1166-1290 s. This accreting white dwarf underwent an outburst in 2006 October, during which its brightness increased by at least five magnitudes, and it started exhibiting superhumps in its light curve. Upon cooling to quiescence, the superhumps disappeared and it displayed the same periods in 2010 February as prior to the outburst within the uncertainties of a couple of seconds. This behavior suggests that the observed variability is likely due to nonradial pulsations in the white dwarf star, whose core structure has not been significantly affected by the outburst. The enigmatic observations begin with an absence of pulsational variability during a multi-site campaign conducted in 2011 January-February without any evidence of a new outburst; the light curve is instead dominated by superhumps with periods in the range of 83-87 minutes. Ultraviolet Hubble Space Telescope time-series spectroscopy acquired in 2011 March reveals an effective temperature of 15,400 K, placing EQ Lyn within the broad instability strip of 10,500-16,000 K for accreting pulsators. The ultraviolet light curve with 90% flux from the white dwarf shows no evidence of any pulsations. Optical photometry acquired during 2011 and Spring 2012 continues to reflect the presence of superhumps and an absence of pulsations. Subsequent observations acquired in 2012 December and 2013 January finally indicate the disappearance of superhumps and the return of pulsational variability with similar periods as previous data. However, our most recent data from 2013 March to May reveal superhumps yet again with no sign of pulsations. We speculate that this enigmatic post-outburst behavior of the frequent disappearance of pulsational variability in EQ Lyn is caused either by heating the white dwarf beyond the instability strip due to an

Effectiveness of peer-counseling for promoting optimal complementary feeding practices among infants belonging to urban slums of Delhi

Directory of Open Access Journals (Sweden)

Sabharwal Vandana, Passi Santosh Jain

2014-04-01

Full Text Available Background : Promotion of appropriate complementary feeding practices is important in reducing malnutrition in infants and young children. Yet, India has dismal rates of optimal complementary feeding practices which are not rising. Aim: This study aimed to find the impact of the educational intervention directed through peer counselors to promote optimal complementary feeding practices. Methods and materials: This is an Interventional study, which has been conducted in an urban slum of Delhi using multi-stage random sampling. From the study area two sectors were randomly selected. From one sector, 54 pregnant women were selected who were not given any counselling forming the non-intervention group. From the other sector, 159 pregnant women were selected to form the intervention group (Igr which were further divided into 3 sub-groups; one sub-group was imparted counselling by a nutrition professional (Igr A; n=53 and the other two (Igr B1;n=53 and Igr B2;n=53 by the peer counselors who where the local health workers trained for promoting optimal infant feeding practices. The infants were followed up till their first birthday and in order to study the impact of counseling, the complementary feeding practices of the intervention and the non-intervention groups have been compared Results: In the intervention groups, the prevalence of exclusive breastfeeding at 6 months was significantly higher as compared to the non-intervention group (67.5 % vs. 4.2 %. In the intervention groups, 2.6 per cent infants received semi-solid/ solid foods before the age of 6 months, 75.1 percent between 6 – 7 months and the rest by the age of 9 months. However, in the Non-Igr, the respective figures were 48.9, 19.4 and 25.4 per cent; and at the age of one year, 6.4 per cent infants were still being given predominantly mother’s milk. 99.3 per cent infants in the Igrs as compared to 82.3 per cent in the Non-Igr (P<0.05 continued to receive breast milk till the age of

Discovery of an old nova shell surrounding the cataclysmic variable V1315 Aql

Science.gov (United States)

Sahman, D. I.; Dhillon, V. S.; Littlefair, S. P.; Hallinan, G.

2018-04-01

Following our tentative discovery of a faint shell around V1315 Aql reported in Sahman et al. (2015), we undertook deep Hα imaging and intermediate-resolution spectroscopy of the shell. We find that the shell has its geometric centre located on V1315 Aql. The mass, spectral features and density of the shell are consistent with other nova shells, rather than planetary nebulae or supernova remnants. The radial velocity of the shell is consistent with the systemic velocity of V1315 Aql. We believe this evidence strongly suggests that the shell originates from an earlier nova event. This is the first nova shell discovered around a novalike, and supports the theory of nova-induced cycles in mass transfer rates (hibernation theory) first proposed by Shara et al. (1986).

Far Ultraviolet Spectroscopic Explorer Spectroscopy of the Nova-Like Cataclysmic Variable BB Doradus

Science.gov (United States)

2008-06-27

which we have best-fit models in the parameter space, we use the infrared magnitudes J, H, and K from the Two Micron All Sky Survey ( 2MASS ) to assess the...in a high state with a visual red magnitude R ¼ 14:60 and a blue magnitude B ¼ 13:90 (whereas B 16:5 in the low state). The 2MASS IR apparent...therefore certainly larger than 300 pc, and most likely in the range of 500 pc. Since BB Dor was observed in a high state (with 2MASS ), it is likely

Far Ultraviolet Spectroscopic Explorer Spectroscopy of the Nova-Like Cataclysmic Variable BB Doradus

National Research Council Canada - National Science Library

Godon, Patrick; Sion, Edward M; Barrett, Paul E; Szkody, Paula; Schlegel, Eric M

2008-01-01

... (possibly lower than 10 ). Assuming an average white dwarf (WD) mass of 0.8 M leads to a mass accretion rate of 10 9 M yr 1 and a distance on the order of 650 pc, consistent with the extremely low Galactic reddening in the direction of BB Dor...

Superoutburst of 0203+56A UV Persei

Science.gov (United States)

Waagen, Elizabeth O.

1991-12-01

Cataclysmic variable 0203+56A UV Per is currently undergoing a superoutburst reaching ~11.5 magnitude. SU UMa is also in superoutburst reaching ~11.7 magnitude. Reiki Kushida made a visual discovery of a supernova in NGC 4374 on December 9.844 UT. 1950 Epoch position is set at 12h 22' 31.54", +13° 08' 52.4". Observations of the supernova its magnitude at ~14.7.

Photometry and Low Dispersion Spectroscopy with ESA Gaia

Czech Academy of Sciences Publication Activity Database

Hudec, R.; Šimon, Vojtěch; Hudec, L.

2010-01-01

Roč. 2010, - (2010), 781421/1-781421/7 ISSN 1687-7969 R&D Projects: GA ČR GA205/08/1207 Grant - others:GA AV ČR(CZ) GA102/09/0997; GA MŠk(CZ) ME09027; ESA(XE) ESA- PECS project No. Institutional research plan: CEZ:AV0Z10030501 Keywords : high-energy sources * cataclysmic variables * low-dispersion spectra Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

The prevalence of depression in White-European and South-Asian people with impaired glucose regulation and screen-detected type 2 diabetes mellitus

DEFF Research Database (Denmark)

Aujla, Navneet; Abrams, Keith R.; Davies, Melanie J.

2009-01-01

) and South-Asian (SA) population attending a community diabetes screening programme, and to explore the association of depression with screen-detected Type 2 diabetes mellitus (T2DM) and impaired glucose regulation (IGR). Methodology/Principal Findings: Participants were recruited from general practices.......9% in WE, 26.4% in SA, p = 0.86). Age-adjusted prevalences were higher for females than males. Odds ratios adjusted for age, gender, and ethnicity, showed no significant increase in prevalent depression for people with T2DM (OR = 0.95, 95%CI 0.62 to 1.45) or IGR (OR = 1.17, 95%CI 0.96 to1.42). Conclusions......: Prior to the knowledge of diagnosis, depression was not significantly more prevalent in people with screen detected T2DM or IGR. Differences in prevalent depression between WE and SA people were also not identified. In this multi-ethnic population, female gender was significantly associated...

Interactive granular computations in networks and systems engineering a practical perspective

CERN Document Server

Jankowski, Andrzej

2017-01-01

The book outlines selected projects conducted under the supervision of the author. Moreover, it discusses significant relations between Interactive Granular Computing (IGrC) and numerous dynamically developing scientific domains worldwide, along with features characteristic of the author’s approach to IGrC. The results presented are a continuation and elaboration of various aspects of Wisdom Technology, initiated and developed in cooperation with Professor Andrzej Skowron. Based on the empirical findings from these projects, the author explores the following areas: (a) understanding the causes of the theory and practice gap problem (TPGP) in complex systems engineering (CSE);(b) generalizing computing models of complex adaptive systems (CAS) (in particular, natural computing models) by constructing an interactive granular computing (IGrC) model of networks of interrelated interacting complex granules (c-granules), belonging to a single agent and/or to a group of agents; (c) developing methodologies based ...

Request for Observations of V405 Peg

Science.gov (United States)

Templeton, Matthew R.

2009-12-01

Dr. Axel Schwope (Astrophysikalisches Institut Potsdam) requests time-series monitoring of the magnetic cataclysmic variable V405 Pegasi from 2009 December 28 through 2009 December 30. These observations are requested in support of a planned XMM-Newton observation of V405 Peg on 2009 December 29 beginning at 18:51 UT (JD 2455195.2854) and continuing for 12.5 hours. Observers are asked to provide intensive coverage during the three day window centered on the XMM-Newton observation to provide information on the activity state of V405 Peg, to improve the orbital ephemeris, and to provide optical data that will help constrain the spectral energy distribution of this poorly understood cataclysmic variable. The primary filters for this observation are Johnson B and Cousins I, but all observations will be useful for determining the orbital ephemeris. V405 Peg may show both orbital modulation as well as changes in its activity level. The orbital period is approximately four hours, and observers are asked to obtain at least ten and preferably more data points per cycle in each filter. Please use exposure times that provide S/N of at least 20 in both the comparison and target stars but short exposure times are preferred to detect flickering and other short-timescale variations. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (http://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

Desmoid-type fibromatosis: a front-line conservative approach to select patients for surgical treatment.

Science.gov (United States)

Fiore, Marco; Rimareix, Françoise; Mariani, Luigi; Domont, Julien; Collini, Paola; Le Péchoux, Cecile; Casali, Paolo G; Le Cesne, Axel; Gronchi, Alessandro; Bonvalot, Sylvie

2009-09-01

Surgery is still the standard treatment for desmoid-type fibromatosis (DF). Recently, the Institut Gustave Roussy (IGR), Villejuif, France, reported a series of patients treated with a front-line conservative approach (no surgery and no radiotherapy). The disease remained stable in more than half of patients. This study was designed to evaluate this approach on the natural history of the disease in a larger series of patients. A total of 142 patients presenting to the IGR or Istituto Nazionale Tumori (INT), Milan, Italy, were initially treated using a front-line deliberately conservative policy. Their progression-free survival (PFS) was observed and a multivariate analysis was performed for major clinical variables. Seventy-four patients presented with primary tumor, 68 with recurrence. Eighty-three patients received a "wait & see" policy (W&S), whereas 59 were initially offered medical therapy (MT), mainly hormonal therapy and chemotherapy. A family history of sporadic colorectal cancer was present in 8% of patients. The 5-year PFS was 49.9% for the W&S group and 58.6% for the medically treated patients (P = 0.3196). Similar results emerged for primary and recurrent DF. Multivariate analysis identified no clinical variables as independent predictors of PFS. In the event of progression, all patients were subsequently managed safely. A conservative policy could be a safe approach to primary and recurrent DF, which could avoid unnecessary morbidity from surgery and/or radiation therapy. Half of patients had medium-term stable disease after W&S or MT. A multidisciplinary, stepwise approach should be prospectively tested in DF.

Crescimento intra-uterino restrito diagnosticado pelo índice ponderal de Rohrer e sua associação com morbidade e mortalidade neonatal precoce Intrauterine growth retardation diagnosed by Rohrer's ponderal index and its association with morbidity and early neonatal mortality

Directory of Open Access Journals (Sweden)

Adehilde Maria Martins Santos

2005-06-01

Full Text Available OBJETIVO: diagnosticar o crescimento intra-uterino restrito (CIUR por meio do índice ponderal de Rohrer e sua associação com morbidade e mortalidade neonatal precoce. MÉTODOS: estudo retrospectivo, descritivo e de coorte transversal, no qual foram incluídos 2741 recém-nascidos (RN, sendo 2053 casos de grávidas hígidas, 228 de pré-eclâmpsia leve (PE, 52 com PE grave, 25 com PE que evoluiu para eclâmpsia, 136 de ruptura prematura das membranas (RPM e 247 de tabagistas. O índice ponderal (IP de Rohrer foi calculado segundo a equação: IP = peso/estatura³ x 100 e se utilizaram os valores 2,25 e 3,10 dos percentis 10 e 90 de Lubchenco. Classificou-se como CIUR assimétrico aquele RN com IP PURPOSE: to diagnose intrauterine growth restriction (IGR and its connection with early neonatal morbidity and mortality, through Roher's ponderal index (PI. METHODS: this was a retrospective, descriptive study of transversal cohort, in which 2741 newborns (NB were included, 2053 of them from healthy pregnant women, 228 from women with mild pregnancy-related hypertension, 52 from those with severe pregnancy-related hypertension, 25 from those with mild pregnancy-related hypertension that evolved to eclampsia, 136 from those with premature membrane rupture, and 247 from women who smoked along gestation. Roher's PI was calculated by the equation: PI = weight/height ³ x 100 and the values 2.25 and 3.10 of Lubchenco's 10 and 90 percentiles were used to classify the types of IGR. IGR was classified as asymmetric for NB with PI < 2.25 and weight lower than percentile 10, as symmetric, with PI from 2.25 to 3.10 and weight lower than percentile 10, and adequate for gestational age with PI from 2.25 to 3.10, and weight from 10 to 90 percentiles. Statistical analysis was performed using the non-paired t test, the non-parametric chi2 test and Fisher's exact test, with significance set at a value of p<0.05. RESULTS: low birth weight (< 2,500 g was present in 3

Pulsating White Dwarfs in Cataclysmic Variables: The Marriage of ZZ Cet and Dwarf Nova

OpenAIRE

Warner, Brian; Woudt, Patrick A.

2003-01-01

There are now four dwarf novae known with white dwarf primaries that show large amplitude non-radial oscillations of the kind seen in ZZ Cet stars. We compare the properties of these stars and point out that by the end of the Sloan Digital Sky Survey more than 30 should be known.

MASTER OT J072007.30+451611.6: Cataclysmic Variable with an Extreme Hot Spot

Science.gov (United States)

Denisenko, D.

2018-05-01

MASTER team has reported an unusual object MASTER OT J072007.30+451611.6 in ATel #11620 (T. Pogrosheva et al.). The object was observed at 17.0-17.2m during 9 minutes from 22:15:26 to 22:24:30 UT on 2018-04-26, but was below the detection limit (18.8m) 45 minutes before the first positive observation and 43 minutes after the last one. As noted by S. Otero in AAVSO VSX entry, MASTER OT J072007.30+451611.6 has an X-ray counterpart XMMSL2 J072007.4+451615.

New Insights from Inside-Out Doppler Tomography

Directory of Open Access Journals (Sweden)

E. J. Kotze

2015-02-01

Full Text Available We present preliminary results from our investigation into using an “inside-out” velocity space for creating a Doppler tomogram. The aim is to transpose the inverted appearance of the Cartesian velocity space used in normal Doppler tomography. In a comparison between normal and inside-out Doppler tomograms of cataclysmic variables, we show that the inside-out velocity space has the potential to produce new insights into the accretion dynamics in these systems.

Intermediate polars observed from Brazil in the last eight years

International Nuclear Information System (INIS)

Jablonski, F.

1988-01-01

The results of observations done, in the last eight years, of the Intermidiate Polars (IP): EX Hya, V1223 Sgr, FO Agr and Ao Psc, are presented. The IP define a subclass of cataclysmic variable stars that present coherent oscillations in their optical and/or X-ray emission. The observations were done from Laboratorio Nacional de Astrofisica, in Itajuba (Brazil). The stability of oscillations in IP was analysed to study the nature of compact stars. (M.C.K.) [pt

Infrared photometry of cataclysmic variables. II - Evidence for ellipsoidal variations in CW MoN, X Leo, IP Peg, and AF CaM

Science.gov (United States)

Szkody, P.; Mateo, M.

1986-08-01

Broadband H or K light curves of the dwarf novae CM Mon, X Leo, IP Peg, and AF Cam reveal variations that can be attributed to ellipsoidal modulation of the secondaries in these systems. The present data imply orbital periods of 4.23 + or - 0.01 hr for CW Mon and 5.0 + or - 0.1 hr for X Leo. The high-amplitude ellipsoidal modulation of the secondary of CW Mon implies a large orbital inclination. The interpretation of the low-amplitude variability seen in X Leo is complicated by details in its light curve and a recent determination of its orbital period by Shafter and Harkness (1986) which differs significantly from the period inferred from the present observations. The light variations of the eclipsing system IP Peg are interpreted as showing a 0.2 mag ellipsoidal variation from the secondary superposed on a deep eclipse of the IR light of the white dwarf and hotspot. AF Cam shows marginal evidence for a low-amplitude variation implying a very short orbital period of 76 min. IR colors of SS Aur, AH Eri, and IR Gem as well as the above four objects are used to place limits on the properties of the secondaries and the distances to these systems.

Topical Anti-Inflammatory Effects of Isorhamnetin Glycosides Isolated from Opuntia ficus-indica

Directory of Open Access Journals (Sweden)

Marilena Antunes-Ricardo

2015-01-01

Full Text Available Opuntia ficus-indica (OFI has been widely used in Mexico as a food and for the treatment of different health disorders such as inflammation and skin aging. Its biological properties have been attributed to different phytochemicals such as the isorhamnetin glycosides which are the most abundant flavonoids. Moreover, these compounds are considered a chemotaxonomic characteristic of OFI species. The aim of this study was to evaluate the effect of OFI extract and its isorhamnetin glycosides on different inflammatory markers in vitro and in vivo. OFI extract was obtained by alkaline hydrolysis of OFI cladodes powder and pure compounds were obtained by preparative chromatography. Nitric oxide (NO, cyclooxygenase-2 (COX-2, tumor necrosis factor- (TNF- α, and interleukin- (IL- 6 production were measured. NO production was tested in lipopolysaccharide-stimulated RAW 264.7 cells while in vivo studies were carried on croton oil-induced ear edema model. OFI extract and diglycoside isorhamnetin-glucosyl-rhamnoside (IGR at 125 ng/mL suppressed the NO production in vitro (73.5 ± 4.8% and 68.7±5.0%, resp. without affecting cell viability. Likewise, IGR inhibited the ear edema (77.4±5.7% equating the indomethacin effects (69.5±5.3%. Both IGR and OFI extract significantly inhibited the COX-2, TNF-α, and IL-6 production. IGR seems to be a suitable natural compound for development of new anti-inflammatory ingredient.

Topical anti-inflammatory effects of isorhamnetin glycosides isolated from Opuntia ficus-indica.

Science.gov (United States)

Antunes-Ricardo, Marilena; Gutiérrez-Uribe, Janet A; Martínez-Vitela, Carlos; Serna-Saldívar, Sergio O

2015-01-01

Opuntia ficus-indica (OFI) has been widely used in Mexico as a food and for the treatment of different health disorders such as inflammation and skin aging. Its biological properties have been attributed to different phytochemicals such as the isorhamnetin glycosides which are the most abundant flavonoids. Moreover, these compounds are considered a chemotaxonomic characteristic of OFI species. The aim of this study was to evaluate the effect of OFI extract and its isorhamnetin glycosides on different inflammatory markers in vitro and in vivo. OFI extract was obtained by alkaline hydrolysis of OFI cladodes powder and pure compounds were obtained by preparative chromatography. Nitric oxide (NO), cyclooxygenase-2 (COX-2), tumor necrosis factor- (TNF-) α, and interleukin- (IL-) 6 production were measured. NO production was tested in lipopolysaccharide-stimulated RAW 264.7 cells while in vivo studies were carried on croton oil-induced ear edema model. OFI extract and diglycoside isorhamnetin-glucosyl-rhamnoside (IGR) at 125 ng/mL suppressed the NO production in vitro (73.5 ± 4.8% and 68.7 ± 5.0%, resp.) without affecting cell viability. Likewise, IGR inhibited the ear edema (77.4 ± 5.7%) equating the indomethacin effects (69.5 ± 5.3%). Both IGR and OFI extract significantly inhibited the COX-2, TNF-α, and IL-6 production. IGR seems to be a suitable natural compound for development of new anti-inflammatory ingredient.

RAZVOJ RAČUNALNIŠKIH IGER S POMOČJO GRAFIČNEGA POGONA UNITY

OpenAIRE

Babič, Teo

2013-01-01

V tej diplomski nalogi bomo pregledali grafični pogon Unity, ki služi kot orodje za razvoj računalniških iger. Spoznali bomo orodja, ki jih grafični pogon Unity uporablja pri izdelovanju iger. To zajema: urejevalnik okolja Unity, materiale in njihove senčnike, delo s fizikalnimi lastnostmi objektov, zvok in orodje za osvetlitev znotraj igre. Vse naštete komponente bomo praktično uporabili in predstavili ob gradnji realno časovne strateške igre Varovanje terena za internetni brskalnik. O...

Patent pool analysis based on technical standards: A case study of indigenous alliances in China

Directory of Open Access Journals (Sweden)

DUAN Yuzhen

2013-07-01

Full Text Available China has set up only two sorts of patent pools (PLs with technical standards, namely, the AVS alliance and IGRS alliance. Both PLs are applied in the IT industry. Statistics of patent alliances with global technical standards show that Chinese enterprises cannot easily form and develop an international PL. This study analyzes the formation process of the AVS and IGRS patent alliance, and points out the challenges in building and developing Chinese PL. The study offers suggestions on alliance management, government guidance, and international cooperation.

Photometry and Multipolar Magnetic Field Modeling of Polars: BY Camelopardalis and FL Ceti

Directory of Open Access Journals (Sweden)

P. A. Mason

2015-02-01

Full Text Available We present new broad band optical photometry of two magnetic cataclysmic variable stars, the asynchronous polar BY Camelopardalis and the short period polar FL Ceti. Observations were obtained at the 2.1-m Otto Struve Telescope of McDonald Observatory with 3s and 1s integration times respectively. In an attempt to understand the observed complex changes in accretion flow geometry observed in BY Cam, we performed full 3D MHD simulations assuming a variety of white dwarf magnetic field structures. We investigate fields with increasing complexity including both aligned and non-aligned dipole plus quadrupole field components. We compare model predictions with photometry at various phases of the beat cycle and find that synthetic light curves derived from a multipolar field structure are broadly consistent with optical photometry. FL Ceti is observed to have two very small accretion regions at the foot-points of the white dwarf’s magnetic field. Both accretion regions are visible at the same time in the high state and are about 100 degrees apart. MHD modeling using a dipole plus quadrupole field structure yields quite similar accretion regions as those observed in FL Ceti. We conclude that accretion flows calculated from MHD modeling of multi-polar magnetic fields produce synthetic light curves consistent with photometry of these magnetic cataclysmic variables.

Reviving the dead: history and reactivation of an extinct l1.

Science.gov (United States)

Yang, Lei; Brunsfeld, John; Scott, LuAnn; Wichman, Holly

2014-06-01

Although L1 sequences are present in the genomes of all placental mammals and marsupials examined to date, their activity was lost in the megabat family, Pteropodidae, ∼24 million years ago. To examine the characteristics of L1s prior to their extinction, we analyzed the evolutionary history of L1s in the genome of a megabat, Pteropus vampyrus, and found a pattern of periodic L1 expansion and quiescence. In contrast to the well-characterized L1s in human and mouse, megabat genomes have accommodated two or more simultaneously active L1 families throughout their evolutionary history, and major peaks of L1 deposition into the genome always involved multiple families. We compared the consensus sequences of the two major megabat L1 families at the time of their extinction to consensus L1s of a variety of mammalian species. Megabat L1s are comparable to the other mammalian L1s in terms of adenosine content and conserved amino acids in the open reading frames (ORFs). However, the intergenic region (IGR) of the reconstructed element from the more active family is dramatically longer than the IGR of well-characterized human and mouse L1s. We synthesized the reconstructed element from this L1 family and tested the ability of its components to support retrotransposition in a tissue culture assay. Both ORFs are capable of supporting retrotransposition, while the IGR is inhibitory to retrotransposition, especially when combined with either of the reconstructed ORFs. We dissected the inhibitory effect of the IGR by testing truncated and shuffled versions and found that length is a key factor, but not the only one affecting inhibition of retrotransposition. Although the IGR is inhibitory to retrotransposition, this inhibition does not account for the extinction of L1s in megabats. Overall, the evolution of the L1 sequence or the quiescence of L1 is unlikely the reason of L1 extinction.

Reviving the dead: history and reactivation of an extinct l1.

Directory of Open Access Journals (Sweden)

Lei Yang

2014-06-01

Full Text Available Although L1 sequences are present in the genomes of all placental mammals and marsupials examined to date, their activity was lost in the megabat family, Pteropodidae, ∼24 million years ago. To examine the characteristics of L1s prior to their extinction, we analyzed the evolutionary history of L1s in the genome of a megabat, Pteropus vampyrus, and found a pattern of periodic L1 expansion and quiescence. In contrast to the well-characterized L1s in human and mouse, megabat genomes have accommodated two or more simultaneously active L1 families throughout their evolutionary history, and major peaks of L1 deposition into the genome always involved multiple families. We compared the consensus sequences of the two major megabat L1 families at the time of their extinction to consensus L1s of a variety of mammalian species. Megabat L1s are comparable to the other mammalian L1s in terms of adenosine content and conserved amino acids in the open reading frames (ORFs. However, the intergenic region (IGR of the reconstructed element from the more active family is dramatically longer than the IGR of well-characterized human and mouse L1s. We synthesized the reconstructed element from this L1 family and tested the ability of its components to support retrotransposition in a tissue culture assay. Both ORFs are capable of supporting retrotransposition, while the IGR is inhibitory to retrotransposition, especially when combined with either of the reconstructed ORFs. We dissected the inhibitory effect of the IGR by testing truncated and shuffled versions and found that length is a key factor, but not the only one affecting inhibition of retrotransposition. Although the IGR is inhibitory to retrotransposition, this inhibition does not account for the extinction of L1s in megabats. Overall, the evolution of the L1 sequence or the quiescence of L1 is unlikely the reason of L1 extinction.

Plasma Asprosin Concentrations Are Increased in Individuals with Glucose Dysregulation and Correlated with Insulin Resistance and First-Phase Insulin Secretion

Directory of Open Access Journals (Sweden)

Yuren Wang

2018-01-01

Full Text Available Background. Adipokines are reported to participate in many common pathologic processes of glucose dysregulation, such as insulin resistance, β-cell dysfunction, and chronic inflammation. Objective. To detect the concentrations of plasma asprosin in subjects with impaired glucose regulation (IGR and newly diagnosed type 2 diabetes (nT2DM and its relationship to parameters of glucose and lipid metabolism, insulin resistance, and pancreatic β-cell function. Methods. 143 eligible participants were included and were divided into three groups including normal glucose regulation (NGR, n=52, IGR (n=40, and nT2DM group (n=51. The intravenous glucose tolerance test (IVGTT and clinical and biochemical parameters were measured in all participants. Results. Plasma asprosin levels were higher in IGR (82.40 ± 91.06 ng/mL, P<0.001 and nT2DM (73.25 ± 91.69 ng/mL, P<0.001 groups compared with those in the NGR (16.22 ± 9.27 ng/mL group, especially in IGR subjects. Correlation analysis showed that plasma asprosin levels were positively correlated with waist circumference (Wc, fasting plasma glucose (FPG, postchallenge plasma glucose (2hPG, HbA1c, triglyceride (TG, and homeostasis model assessment for insulin resistance (HOMA-IR and negatively correlated with homeostasis model assessment for β-cell function (HOMA-β, area under the curve of the first-phase (0–10 min insulin secretion (AUC, acute insulin response (AIR, and glucose disposition index (GDI (all P<0.05. Multiple logistical regression analyses revealed that plasma asprosin concentrations were significantly correlated with IGR and nT2DM after controlling for age, sex, BMI, and WHR. Conclusions. Circulating asprosin might be a predictor of early diagnosis in DM and might be a potential therapeutic target for prediabetes and T2DM.

On the nature of WX Ceti

International Nuclear Information System (INIS)

Downes, R.A.; Margon, B.

1981-01-01

WX Ceti is a large amplitude (8 mag) variable which has undergone at least four outbursts during this century. Bailey has suggested that this object may be related to WZ Sge, and is part of a small but distinct subgroup of dwarf novae. Spectroscopy of WX Cet has been obtained at minimum light, revealing extremely strong, broad Balmer emission, but no He II lambda 4686. The spectrum indeed resembles WZ Sge at minimum, although it lacks the broad Balmer absorptions of the latter object. The data confirm the cataclysmic variable nature of WX Cet, and indicate that the proposed association with WZ Sge is plausible. (author)

Dosimetric consequences of translational and rotational errors in frame-less image-guided radiosurgery

International Nuclear Information System (INIS)

Guckenberger, Matthias; Roesch, Johannes; Baier, Kurt; Sweeney, Reinhart A; Flentje, Michael

2012-01-01

To investigate geometric and dosimetric accuracy of frame-less image-guided radiosurgery (IG-RS) for brain metastases. Single fraction IG-RS was practiced in 72 patients with 98 brain metastases. Patient positioning and immobilization used either double- (n = 71) or single-layer (n = 27) thermoplastic masks. Pre-treatment set-up errors (n = 98) were evaluated with cone-beam CT (CBCT) based image-guidance (IG) and were corrected in six degrees of freedom without an action level. CBCT imaging after treatment measured intra-fractional errors (n = 64). Pre- and post-treatment errors were simulated in the treatment planning system and target coverage and dose conformity were evaluated. Three scenarios of 0 mm, 1 mm and 2 mm GTV-to-PTV (gross tumor volume, planning target volume) safety margins (SM) were simulated. Errors prior to IG were 3.9 mm ± 1.7 mm (3D vector) and the maximum rotational error was 1.7° ± 0.8° on average. The post-treatment 3D error was 0.9 mm ± 0.6 mm. No differences between double- and single-layer masks were observed. Intra-fractional errors were significantly correlated with the total treatment time with 0.7mm±0.5mm and 1.2mm±0.7mm for treatment times ≤23 minutes and >23 minutes (p<0.01), respectively. Simulation of RS without image-guidance reduced target coverage and conformity to 75% ± 19% and 60% ± 25% of planned values. Each 3D set-up error of 1 mm decreased target coverage and dose conformity by 6% and 10% on average, respectively, with a large inter-patient variability. Pre-treatment correction of translations only but not rotations did not affect target coverage and conformity. Post-treatment errors reduced target coverage by >5% in 14% of the patients. A 1 mm safety margin fully compensated intra-fractional patient motion. IG-RS with online correction of translational errors achieves high geometric and dosimetric accuracy. Intra-fractional errors decrease target coverage and conformity unless compensated with appropriate

Effects of lifestyle intervention and meal replacement on glycaemic and body-weight control in Chinese subjects with impaired glucose regulation: a 1-year randomised controlled trial.

Science.gov (United States)

Xu, Dan-Feng; Sun, Jian-Qin; Chen, Min; Chen, Yan-Qiu; Xie, Hua; Sun, Wei-Jia; Lin, Yi-Fan; Jiang, Jing-Jing; Sun, Wei; Chen, Ai-Fang; Tang, Qian-Ru

2013-02-14

The purpose of the present study was to evaluate the impact of a lifestyle intervention programme, combined with a daily low-glycaemic index meal replacement, on body-weight and glycaemic control in subjects with impaired glucose regulation (IGR). Subjects with IGR were randomly assigned to an intervention group (n 46) and a control group (n 42). Both groups received health counselling at baseline. The intervention group also received a daily meal replacement and intensive lifestyle intervention to promote healthy eating habits during the first 3 months of the study, and follow-up visits performed monthly until the end of the 1-year study. Outcome measurements included changes in plasma glucose, glycated Hb (HbA1c), plasma lipids, body weight, blood pressure and body composition (such as body fat mass and visceral fat area). The results showed that body-weight loss after 1 year was significant in the intervention group compared with the control group (-1·8 (SEM 0·35) v. -0·6 (SEM 0·40) 2·5 kg, Pmeal replacement is beneficial in promoting IGR to NGR.

Disc structure and variability in dwarf novae

Science.gov (United States)

Harlaftis, Emilios Theofanus

An introduction is given to dwarf novae reviewing the current research status in the field. We present IUE observations of Z Cha which support the mass transfer instability as the cause of the superoutbursts observed in SU UMa type dwarf novae. Comparison between the superoutburst and a normal outburst of Z Cha shows that the disc is flatter and has significantly less azimuthal structure than during superoutburst. Z Cha exhibits a soft x-ray deficit during superoutburst compared to OY Car. We find that the secondary star of Z Cha contributes approximately 30 percent of the infrared flux at peak of outburst. The second part of the thesis presents results from the 1988 International Time Project at the Observatorio del Roque de los Muchachos. Investigation of the behavior of SU UMa and YZ Cnc is carried out through the outburst cycle. The secular changes of the equivalent widths of both systems shows an increasing trend even during quiescence and are caused by the continuum decrease. Both systems show a low-velocity emission component which contaminates the wings of the H(alpha) profile. In addition to doppler broadening, the Stark effect is found to cause significant broadening to the line profile. The radial dependence of the emission lines is discussed in relation to other cataclysmic variables. H(alpha) emission from the secondary star of YZ Cnc is found during superoutburst, during outburst and during quiescence after outburst. Photometry during late decline of outburst shows a sinusoidal, weak variation peaking at 0.5 orbital phase and which is related to heating of the red star or to a transient disc event. During quiescence, the flickering is found to be caused by the bright spot. This modulation increases with time and is maximum before the outburst. Doppler tomography of IP Peg during quiescence reveals an emission line distribution not consistent to the standard model. We find Balmer emission from the secondary star, at a level of only 2.5 percent of the

MISTERIJA ŠAHOVSKE IGRE

Directory of Open Access Journals (Sweden)

Dragan Drobnjak

2006-06-01

Full Text Available If we relife of enigmatic, unexplainable, and partly mysterious, the chess game would lose much of its genuine nature, which wouldne, to be characterized any more by that original allure of enchanting.Chess game does not reveal all its secrets neither in regard to its origin nor in regard to its place in the life of an individual or the society.Therefore, chess game is extremely interesting filed of research from the sociological, socio-psychological, anthropological, cultural and other aspects. While elaborating this theme from all these aspects i have tried to come up with the answer to the question:Where is the beginning and the end of the chess game?On this questin, until now no one has given the precise answer, the answer which acknoweledges the thesis that mystery of the chess game has not yet been resolved, and we dont, know if will be and when it will be resolved.

The White Dwarf Mass and the Accretion Rate of Recurrent Novae: An X-ray Perspective

Science.gov (United States)

Mukai, Koji; Sokoloski, Jennifer L.; Nelson, Thomas; Luna, Gerardo J. M.

2011-01-01

We present recent results of quiescent X-ray observations of recurrent novae (RNe) and related objects. Several RNe are luminous hard X-ray sources in quiescence, consistent with accretion onto a near Chandrasekhar mass white dwarf. Detection of similar hard X-ray emissions in old novae and other cataclysmic variables may lead to identification of additional RN candidates. On the other hand, other RNe are found to be comparatively hard X-ray faint. We present several scenarios that may explain this dichotomy, which should be explored further.

Using variants of CHC Algorithms in the Design of Radio Frequency Networks in Wireless Communications.

Directory of Open Access Journals (Sweden)

Daniel Antonio Molina

2015-09-01

Full Text Available In this paper we apply to solve the Radio Network Design problem (RND a series  of the non-conventional genetic algorithms called Cross generational elitist selection Heterogeneous recombination Cataclysmic mutation (CHC. A set of genetic algorithms is used to perform a comparative performance of the proposed algorithms. An objective function based on signal coverage efficiency is used. Genetic variability of the population is used for both, as a parameter of convergence and detection of incest. Furthermore the variability of the best individual is proposed as a shaking mechanism. This allows generating dynamic populations according to the most promising solutions generating different search spaces. The results obtained by the proposed algorithms are satisfactory.

Infrared observations of AE Aquarii

Science.gov (United States)

Tanzi, E. G.; Chincarini, G.; Tarenghi, M.

1981-01-01

Broadband infrared observations of the cataclysmic variable AE Aquarii are reported. The observations were obtained in the J, H, K and L filters with the InSb photometer attached to the 1-m telescope of the European Southern Observatory. The infrared energy distribution observed from 0.35 to 3.5 microns for phase 0.5 suggests a spectral type of K5 V for the secondary and a distance to the system of approximately 70 pc if an absolute magnitude of 7.3 is assumed. Monitoring of the flux at 2.2 microns reveals a variability with an amplitude of approximately 0.3 magnitude over one third of the orbital period, the nature of which is under investigation.

Computing Cosmic Cataclysms

Science.gov (United States)

Centrella, Joan M.

2010-01-01

The final merger of two black holes releases a tremendous amount of energy, more than the combined light from all the stars in the visible universe. This energy is emitted in the form of gravitational waves, and observing these sources with gravitational wave detectors requires that we know the pattern or fingerprint of the radiation emitted. Since black hole mergers take place in regions of extreme gravitational fields, we need to solve Einstein's equations of general relativity on a computer in order to calculate these wave patterns. For more than 30 years, scientists have tried to compute these wave patterns. However, their computer codes have been plagued by problems that caused them to crash. This situation has changed dramatically in the past few years, with a series of amazing breakthroughs. This talk will take you on this quest for these gravitational wave patterns, showing how a spacetime is constructed on a computer to build a simulation laboratory for binary black hole mergers. We will focus on the recent advances that are revealing these waveforms, and the dramatic new potential for discoveries that arises when these sources will be observed.

On the formation of TW Crv optical radiation

Science.gov (United States)

Shimansky, V. V.; Mitrofanova, A. A.; Borisov, N. V.; Fabrika, S. N.; Galeev, A. I.

2016-10-01

We present the analysis of the optical radiation of the young pre-cataclysmic variable TW Crv. Spectroscopic and photometric observations were obtained at the SAO RAS 6-m BTA telescope and at the Russian-Turkish RTT-150 telescope. The light curves of the system posses nearly sinusoidal shapes with the amplitudes of Δ m > 0.m7, what is typical for young pre-cataclysmic variables with sdO-subdwarfs and orbit inclinations of less than 45◦. The optical spectrum contains dominant radiation of the hot subdwarf with the HI and He II absorption lines and strong emission lines, which are formed in the atmosphere of the secondary owing to the reflection effects. Radial velocities of the cool star were measured by analyzing the λλ 4630-4650 Å Bowen blend, which for the first time allowed to determine the component masses. A numerical simulation of the light curves and spectra of TW Crv, obtaining a complete set of systems fundamental parameters was carried out. The hot star parameters prompt its belonging to the sdOsubdwarf class at the stage of transition to the cooling white dwarf sequence. The absence of its observable planetary nebula is caused by a long-lasting evolution of the system after the common envelope state. The secondary component has a luminosity excess, which is typical for other young sdO-subdwarf precataclysmic variables. Its position on the " age-luminosity excess" diagram points at the accuracy of the obtained set of TW Crv fundamental parameters and at the similarity of its evolutionary and physical conditions with that of other BE UMa-type objects.

An analysis of feature relevance in the classification of astronomical transients with machine learning methods

Science.gov (United States)

D'Isanto, A.; Cavuoti, S.; Brescia, M.; Donalek, C.; Longo, G.; Riccio, G.; Djorgovski, S. G.

2016-04-01

The exploitation of present and future synoptic (multiband and multi-epoch) surveys requires an extensive use of automatic methods for data processing and data interpretation. In this work, using data extracted from the Catalina Real Time Transient Survey (CRTS), we investigate the classification performance of some well tested methods: Random Forest, MultiLayer Perceptron with Quasi Newton Algorithm and K-Nearest Neighbours, paying special attention to the feature selection phase. In order to do so, several classification experiments were performed. Namely: identification of cataclysmic variables, separation between galactic and extragalactic objects and identification of supernovae.

Recent advances on the formation and evolution of white dwarfs

International Nuclear Information System (INIS)

Sion, E.M.

1986-01-01

Advances made in the past seven years in both the theory and observation of white dwarfs which have led to major progress in understanding white dwarf formation and evolution are reviewed. The roles of convective dredge-up, mixing and dilution, accretion, gravitational and thermal diffusion in dense plasmas, radiate forces and mass outflow, nuclear shell burning, diffusion-induced reactions, late thermonuclear shell flashes, rotation, and magnetic fields in white dwarf evolution are considered. Recent work on the properties of white dwarfs in cataclysmic variables is briefly addressed. 153 references

Investigation of high-energy sources in optical light by ESA Gaia

Czech Academy of Sciences Publication Activity Database

Hudec, R.; Šimon, Vojtěch; Hudec, L.; Hudcová, Věra

2010-01-01

Roč. 81, č. 1 (2010), s. 476-481 ISSN 0037-8720. [Multifrequency behaviour of high energy cosmic sources. Vulcano, 25.05.2009-30.05. 2009] R&D Projects: GA ČR GA205/08/1207 Grant - others:ESA(XE) ESA- PECS project No. 98058; GA ČR(CZ) GA102/09/0997; GA MŠk(CZ) ME09027; ESA(XE) ESA- PECS project No. 98023 Institutional research plan: CEZ:AV0Z10030501 Keywords : high-energy sources * cataclysmic variables * low-dispersion spectra Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

The evolutionary status of symbiotic stars

International Nuclear Information System (INIS)

Rudak, B.

1982-01-01

The evolutionary relations between symbiotic stars and cataclysmic variables are presented. The symbiotic stars are assumed to be long period detached binaries containing a carbon-oxygen degenerate primary and a red giant losing its mass through a spherically symmetric wind. Such systems can be obtained in Case C evolution, provided a common envelope during a rapid mass transfer phase was not formed. The same way recurrent novae containing a red giant as a secondary component may be produced. The factors influencing the differences between symbiotic stars and nova-type stars are discussed. (Auth.)

Bioefficacy of Insect Growth Regulators Against Aedes albopictus (Diptera: Culicidea) From Sarawak, Malaysia: A Statewide Survey.

Science.gov (United States)

Lau, Koon Weng; Chen, Chee Dhang; Lee, Han Lim; Low, Van Lun; Sofian-Azirun, Mohd

2018-05-28

The susceptibility status of Aedes albopictus (Skuse; Diptera: Culicidea) larvae collected from 13 districts in Sarawak state, Malaysia was evaluated against five insect growth regulators (IGRs) namely, methoprene, pyriproxyfen, diflubenzuron, cyromazine, and novaluron. Field populations of Ae. albopictus were susceptible to methoprene, pyriproxyfen, cyromazine and novaluron with resistance ratios (RRs) ranging from 0.19-0.38, 0.05-0.14, 0.50-0.95, and 0.75-1.00, respectively. Nevertheless, tolerance towards diflubenzuron (0.33-1.33) was observed in this study. In general, these IGRs exhibited promising results and can be used as alternative control agents against field populations of Ae. albopictus in Sarawak, Malaysia.

WIND VARIABILITY IN BZ CAMELOPARDALIS

International Nuclear Information System (INIS)

Honeycutt, R. K.; Kafka, S.; Robertson, J. W.

2013-01-01

Sequences of spectra of the nova-like cataclysmic variable (CV) BZ Cam were acquired on nine nights in 2005-2006 in order to study the time development of episodes of wind activity known to occur frequently in this star. We confirm the results of Ringwald and Naylor that the P-Cygni absorption components of the lines mostly evolve from higher expansion velocity to lower velocity as an episode progresses. We also commonly find blueshifted emission components in the Hα line profile, whose velocities and durations strongly suggest that they are also due to the wind. Curiously, Ringwald and Naylor reported common occurrences of redshifted Hα emission components in their BZ Cam spectra. We have attributed these emission components in Hα to occasions when gas concentrations in the bipolar wind (both front side and back side) become manifested as emission lines as they move beyond the disk's outer edge. We also suggest, based on changes in the P-Cygni profiles during an episode, that the progression from larger to smaller expansion velocities is due to the higher velocity portions of a wind concentration moving beyond the edge of the continuum light of the disk first, leaving a net redward shift of the remaining absorption profile. We derive a new orbital ephemeris for BZ Cam, using the radial velocity of the core of the He I λ5876 line, finding P = 0.15353(4). Using this period, the wind episodes in BZ Cam are found to be concentrated near the inferior conjunction of the emission line source. This result helps confirm that the winds in nova-like CVs are often phase dependent, in spite of the puzzling implication that such winds lack axisymmetry. We argue that the radiation-driven wind in BZ Cam receives an initial boost by acting on gas that has been lifted above the disk by the interaction of the accretion stream with the disk, thereby imposing flickering timescales onto the wind events, as well as leading to an orbital modulation of the wind due to the non

Backyard Telescopes Watch an Expanding Binary

Science.gov (United States)

Kohler, Susanna

2018-01-01

What can you do with a team of people armed with backyard telescopes and a decade of patience? Test how binary star systems evolve under Einsteins general theory of relativity!Unusual VariablesCataclysmic variables irregularly brightening binary stars consisting of an accreting white dwarf and a donor star are a favorite target among amateur astronomers: theyre detectable even with small telescopes, and theres a lot we can learn about stellar astrophysics by observing them, if were patient.Diagram of a cataclysmic variable. In an AM CVn, the donor is most likely a white dwarf as well, or a low-mass helium star. [Philip D. Hall]Among the large family of cataclysmic variables is one unusual type: the extremely short-period AM Canum Venaticorum (AM CVn) stars. These rare variables (only 40 are known) are unique in having spectra dominated by helium, suggesting that they contain little or no hydrogen. Because of this, scientists have speculated that the donor stars in these systems are either white dwarfs themselves or very low-mass helium stars.Why study AM CVn stars? Because their unusual configuration allows us to predict the behavior of their orbital evolution. According to the general theory of relativity, the two components of an AM CVn will spiral closer and closer as the system loses angular momentum to gravitational-wave emission. Eventually they will get so close that the low-mass companion star overflows its Roche lobe, beginning mass transfer to the white dwarf. At this point, the orbital evolution will reverse and the binary orbit will expand, increasing its period.CBA member Enrique de Miguel, lead author on the study, with his backyard telescope in Huelva, Spain. [Enrique de Miguel]Backyard Astronomy Hard at WorkMeasuring the evolution of an AM CVns orbital period is the best way to confirm this model, but this is no simple task! To observe this evolution, we first need a system with a period that can be very precisely measured best achieved with an

Classification of X-ray sources in the XMM-Newton serendipitous source catalog: Objects of special interest

Energy Technology Data Exchange (ETDEWEB)

Lin, Dacheng; Webb, Natalie A.; Barret, Didier, E-mail: dlin@ua.edu [CNRS, IRAP, 9 Avenue du Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4 (France)

2014-01-01

We analyze 18 sources that showed interesting properties of periodicity, very soft spectra, and/or large long-term variability in X-rays in our project of classification of sources from the 2XMMi-DR3 catalog, but were poorly studied in the literature, in order to investigate their nature. Two hard sources show X-ray periodicities of ∼1.62 hr (2XMM J165334.4–414423) and ∼2.1 hr (2XMM J133135.2–315541) and are probably magnetic cataclysmic variables. One source, 2XMM J123103.2+110648, is an active galactic nucleus (AGN) candidate showing very soft X-ray spectra (kT ∼ 0.1 keV) and exhibiting an intermittent ∼3.8 hr quasi-periodic oscillation. There are six other very soft sources (with kT < 0.2 keV), which might be in other galaxies with luminosities between ∼10{sup 38}-10{sup 42} erg s{sup –1}. They probably represent a diverse group that might include objects such as ultrasoft AGNs and cool thermal disk emission from accreting intermediate-mass black holes. Six highly variable sources with harder spectra are probably in nearby galaxies with luminosities above 10{sup 37} erg s{sup –1} and thus are great candidates for extragalactic X-ray binaries. One of them (2XMMi J004211.2+410429, in M31) is probably a new-born persistent source, having been X-ray bright and hard in 0.3-10 keV for at least four years since it was discovered entering an outburst in 2007. Three highly variable hard sources appear at low galactic latitudes and have maximum luminosities below ∼10{sup 34} erg s{sup –1} if they are in our Galaxy. Thus, they are great candidates for cataclysmic variables or very faint X-ray transients harboring a black hole or neutron star. Our interpretations of these sources can be tested with future long-term X-ray monitoring and multi-wavelength observations.

CXCR6, a newly defined biomarker of tissue-specific stem cell asymmetric self-renewal, identifies more aggressive human melanoma cancer stem cells.

Directory of Open Access Journals (Sweden)

Rouzbeh Taghizadeh

2010-12-01

Full Text Available A fundamental problem in cancer research is identifying the cell type that is capable of sustaining neoplastic growth and its origin from normal tissue cells. Recent investigations of a variety of tumor types have shown that phenotypically identifiable and isolable subfractions of cells possess the tumor-forming ability. In the present paper, using two lineage-related human melanoma cell lines, primary melanoma line IGR39 and its metastatic derivative line IGR37, two main observations are reported. The first one is the first phenotypic evidence to support the origin of melanoma cancer stem cells (CSCs from mutated tissue-specific stem cells; and the second one is the identification of a more aggressive subpopulation of CSCs in melanoma that are CXCR6+.We defined CXCR6 as a new biomarker for tissue-specific stem cell asymmetric self-renewal. Thus, the relationship between melanoma formation and ABCG2 and CXCR6 expression was investigated. Consistent with their non-metastatic character, unsorted IGR39 cells formed significantly smaller tumors than unsorted IGR37 cells. In addition, ABCG2+ cells produced tumors that had a 2-fold greater mass than tumors produced by unsorted cells or ABCG2- cells. CXCR6+ cells produced more aggressive tumors. CXCR6 identifies a more discrete subpopulation of cultured human melanoma cells with a more aggressive MCSC phenotype than cells selected on the basis of the ABCG2+ phenotype alone.The association of a more aggressive tumor phenotype with asymmetric self-renewal phenotype reveals a previously unrecognized aspect of tumor cell physiology. Namely, the retention of some tissue-specific stem cell attributes, like the ability to asymmetrically self-renew, impacts the natural history of human tumor development. Knowledge of this new aspect of tumor development and progression may provide new targets for cancer prevention and treatment.

Frame and frameless linear accelerator-based radiosurgery for idiopathic trigeminal neuralgia.

Science.gov (United States)

Chen, Allan Y; Hsieh, Yen; McNair, Steffanie; Li, Qijuan; Xu, Kevin Y; Pappas, Conrad

2015-01-01

We report outcome of linear accelerator (Linac)-based stereotactic radiosurgery (SRS) for trigeminal neuralgia (TGN) utilizing rigid head frame (RF) and facemask (FM) immobilization.Method: From November 2008 to October 2012, 48 patients with idiopathic TGN underwent primary SRS by a dedicated Linac. RF immobilization was utilized for 34 patients, and frameless image-guided radiosurgery (IGRS) with FM immobilization was performed in 14 patients. Treatment outcome was assessed by patient interviews with a 7-item questionnaire. Sub-millimeter targeting accuracy (0.71±0.31 mm) was recorded for frameless IGRS by a novel hidden-target phantom method. With a follow-up of 26 months, significant pain relief was recorded in 43 (89%) patients, including 26 (54%) complete and 17 (35%) partial responses; with a significant reduction of 2.4±1.3 points ( p < 0.01) on the 5-point Barrow Neurological Institute pain scale. No significant pain relief difference ( p = 0.23) was detected between patients immobilized by RF and FM. Notable pin site problems were reported in 9 (26%) of 34 patients immobilized by RF. Frameless IGRS with FM immobilization is more patient friendly and can achieve as excellent treatment outcome as with RF immobilization for idiopathic TGN.

ORIGIN OF THE GALACTIC DIFFUSE X-RAY EMISSION: IRON K-SHELL LINE DIAGNOSTICS

Energy Technology Data Exchange (ETDEWEB)

Nobukawa, Masayoshi [Department of Teacher Training and School Education, Nara University of Education, Takabatake-cho, Nara, 630-8528 (Japan); Uchiyama, Hideki [Faculty of Education, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka, 422-8529 (Japan); Nobukawa, Kumiko K.; Koyama, Katsuji [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-oiwake-cho, Sakyo-ku, Kyoto, 606-8502 (Japan); Yamauchi, Shigeo, E-mail: nobukawa@nara-edu.ac.jp [Department of Physics, Nara Women’s University, Kitauoyanishimachi, Nara, 630-8506 (Japan)

2016-12-20

This paper reports detailed K-shell line profiles of iron (Fe) and nickel (Ni) of the Galactic Center X-ray Emission (GCXE), Galactic Bulge X-ray Emission (GBXE), Galactic Ridge X-ray Emission (GRXE), magnetic Cataclysmic Variables (mCVs), non-magnetic Cataclysmic Variables (non-mCVs), and coronally Active Binaries (ABs). For the study of the origin of the GCXE, GBXE, and GRXE, the spectral analysis is focused on equivalent widths of the Fe i-K α , Fe xxv-He α , and Fe xxvi-Ly α  lines. The global spectrum of the GBXE is reproduced by a combination of the mCVs, non-mCVs, and ABs spectra. On the other hand, the GRXE spectrum shows significant data excesses at the Fe i-K α and Fe xxv-He α  line energies. This means that additional components other than mCVs, non-mCVs, and ABs are required, which have symbiotic phenomena of cold gas and very high-temperature plasma. The GCXE spectrum shows larger excesses than those found in the GRXE spectrum at all the K-shell lines of iron and nickel. Among them the largest ones are the Fe i-K α , Fe xxv-He α , Fe xxvi-Ly α , and Fe xxvi-Ly β  lines. Together with the fact that the scale heights of the Fe i-K α , Fe xxv-He α , and Fe xxvi-Ly α lines are similar to that of the central molecular zone (CMZ), the excess components would be related to high-energy activity in the extreme envelopment of the CMZ.

Origin of very-short orbital-period binary systems

International Nuclear Information System (INIS)

Miyaji, S.

1983-01-01

Recent observations of four close binaries have established that there is a group of very-short orbital-period (VSOP) binaries whose orbital periods are less than 60 minutes. The VSOP binaries consist of both X-ray close binaries and cataclysmic variables. Their orbital periods are too short to have a main-sequence companion. However, four binaries, none of which belongs to any globular cluster, are too abundant to be explained by the capturing mechanism of a white dwarf. Therefore it seemed to be worthwhile to present an evolutionary scenario from an original binary system which can be applied for all VSOP binaries. (Auth.)

Main: Clone Detail [KOME

Lifescience Database Archive (English)

Full Text Available Clone Detail Mapping Pseudomolecule data detail Detail information Mapping to the T...IGR japonica Pseudomolecules kome_mapping_pseudomolecule_data_detail.zip kome_mapping_pseudomolecule_data_detail ...

A soft mHz quasi periodic oscillation in the fastest accreting millisecond pulsar.

Science.gov (United States)

Ferrigno, C.; Bozzo, E.; Sanna, A.; Pintore, F.; Papitto, A.; Riggio, A.; Burderi, L.; Di Salvo, T.; Iaria, R.; D'ai, A.

2017-10-01

We illustrate the peculiar X-ray variability displayed by the accreting millisecond X-ray pulsar IGR J00291+5934 in a 80 ks-long joint Nustar and XMM-Newton observation performed during the source outburst in 2015. The lightcurve of the source is characterized by a flaring behavior, with typical rise and decay timescales of ˜120 s. The flares are accompanied by a remarkable spectral variability, with the X- ray emission being generally softer at the peak of the flares. A strong QPO is detected at ˜8 mHz in the power spectrum of the source and clearly associated to its flaring-like behaviour. This feature has the strongest power at soft X-rays (hearth-beat in the black-hole binary GRS 1915+105, or, less likely, to unstable nuclear burning on the neutron star surface, as observed in the burster 4U 1636-536. This phenomenology could be ideally studied with the large throughput and wide energy coverage of present and future instruments.

Monte Carlo investigation of design aspects of indigenously developed 120 Ci 60Co based industrial radiography device

International Nuclear Information System (INIS)

Palam Selvam, T.; Vishwakarma, R.S.; Sahoo, Dhiren K.; Sharma, Manoj K.; Srivastava, Piyush

2016-01-01

Industrial Radiography is an indispensable, versatile and well-established non destructive testing (NDT). Industrial radiography is carried out by using industrial radiography gamma exposure devices (IGRED) housing 60 Co and 192 Ir radioactive sources, and Industrial X-ray machines/accelerators. IGRED is an assembly of components which includes source housing, exposure mechanism, source drive system, pig tail, and source conduit. In the present study, we investigated the shielding design aspects of 120 Ci 60 Co-based IRGED using the Monte Carlo methods (MCNP version 3.1). The design details were provided by Board of Radiation and Isotope Technology (BRIT). As the objective is to finalize the suitable design of the device, we also included additional designs. The work also included measurements around the device using TLDs

An overview of industrial radiography accidents in India during the period 1987-1997

International Nuclear Information System (INIS)

Kumar, A.; Subramanya, M.J.; Raghavendran, C.P.; Murthy, B.K.S.; Vishwakarma, R.R.; Kannan, R.; Sharma, A.; Bhatt, B.C.

1998-01-01

Use of gamma radiation sources for non-destructive testing of welds, castings and vital components in several industries in India has recorded a steep rise in the last three decades. There are over 1000 industrial gamma radiography exposure devices (IGRED) in over 400 institutions in the country. Most of these employ Co-60 and Ir-192 gamma sources. In spite of regulatory control and procedures there have been accidents with the IGREDs resulting in significant radiation exposures and in some cases, injuries to members of public and radiography personnel. This paper analyses the accidents which occurred in India during the ten year period of 1987-1997, management of such accidents, steps taken to avoid recurrence of these accidents based on the lessons learnt. (author)

Limitations of mitochondrial gene barcoding in Octocorallia.

Science.gov (United States)

McFadden, Catherine S; Benayahu, Yehuda; Pante, Eric; Thoma, Jana N; Nevarez, P Andrew; France, Scott C

2011-01-01

The widespread assumption that COI and other mitochondrial genes will be ineffective DNA barcodes for anthozoan cnidarians has not been well tested for most anthozoans other than scleractinian corals. Here we examine the limitations of mitochondrial gene barcoding in the sub-class Octocorallia, a large, diverse, and ecologically important group of anthozoans. Pairwise genetic distance values (uncorrected p) were compared for three candidate barcoding regions: the Folmer region of COI; a fragment of the octocoral-specific mitochondrial protein-coding gene, msh1; and an extended barcode of msh1 plus COI with a short, adjacent intergenic region (igr1). Intraspecific variation was barcodes, and there was no discernible barcoding gap between intra- and interspecific p values. In a case study to assess regional octocoral biodiversity, COI and msh1 barcodes each identified 70% of morphospecies. In a second case study, a nucleotide character-based analysis correctly identified 70% of species in the temperate genus Alcyonium. Although interspecific genetic distances were 2× greater for msh1 than COI, each marker identified similar numbers of species in the two case studies, and the extended COI + igr1 + msh1 barcode more effectively discriminated sister taxa in Alcyonium. Although far from perfect for species identification, a COI + igr1 + msh1 barcode nonetheless represents a valuable addition to the depauperate set of characters available for octocoral taxonomy. © 2010 Blackwell Publishing Ltd.

Methodology and results of investigations of physical parameters of high-temperature reactors

International Nuclear Information System (INIS)

Cherepnin, Yu.S.; Chertkov, Yu.B.

1995-01-01

A physical investigations of reactors of stand complexes Baikal-1 and IGR have been carrying out more 30 years. Measuring methods of the physical investigations were divided into 2 groups: 1) methods for measuring of reactivity effects; 2) methods for measuring relative and absolute values of neutron flux and power release. The physical investigations on the reactors IVG-1 and IGR were carryied out under following conditions: during physical starts-up of regular variants of reactor cores; during energy starts-up of the reactors; before beginning of new loop chanel tests of the reactors; during research hot starts-up of the reactors the physical parameters were controled. The most full and authentic information about studied reactor have been providing by physical investigations. In 1984 physical investigations were carryied out on the IGR reactor and then the hot start-up of the mostest power and mostest large on fuel loading loop chanel was carryied out. This chanel contained 6 fuel assemblies with the summary fuel loading 3,06 kilogrammes of uranium and it was calculated for power equal to 20 MW. In 1988 the physical investigations for selection of project process chanels destined for new water cooled reactor core were carryied out. In 1993 the neutron-physical calculation on possibility of tests for the rector Nerva fuel element was carryied out. 9 refs., 4 figs

High sensitivity C-reactive protein and its relationship with impaired glucose regulation in lean patients with polycystic ovary syndrome.

Science.gov (United States)

Kim, Ji Won; Han, Ji Eun; Kim, You Shin; Won, Hyung Jae; Yoon, Tae Ki; Lee, Woo Sik

2012-04-01

The polycystic ovary syndrome (PCOS) is the most common endocrine-metabolic disorder, also associated with the metabolic syndrome. Serum high sensitivity C-reactive protein (hs-CRP), a marker of low-grade chronic inflammation is a potent predictor of cardiovascular events, closely linked to metabolic syndrome features and higher in patients with PCOS. However, hs-CRP in lean patients with PCOS has not been fully evaluated and few data are available. We aimed to investigate the relation between glucose intolerance and hs-CRP levels in lean patients with PCOS, and to evaluate the possible relationship between hs-CRP and PCOS by evaluating PCOS-related metabolic abnormalities in Korean women. We consecutively recruited 115 lean (BMI PCOS and 103 lean healthy controls. The PCOS group was divided two groups: impaired glucose regulation (IGR) and normal glucose tolerance group (NGT). In lean patients with PCOS, hs-CRP level was higher in the IGR group than in the NGT group (0.60 ± 1.37 versus 0.18 ± 0.46, p(Bonf) = 0.023) and other metabolic risk factors were also higher in the IGR group than in the NGT group. And there were close relationships between hs-CRP level and metabolic risk factor, such as 2 h postprandial insulin level in the lean patients with PCOS.

Insulin resistance in human subjects having impaired glucose regulation

International Nuclear Information System (INIS)

Khan, S.H.; Khan, F.A.; Ijaz, A.

2007-01-01

To determine insulin resistance in human subjects having impaired glucose regulation (IGR) by Homeostasis Model Assessment for Insulin Resistance (HOMA-IR). A total of 100 subjects with impaired glucose regulation were selected for evaluation of metabolic syndrome as per the criteria of National Cholesterol Education Program, Adult Treatment Panel III (NCEP, ATP III), along with 47 healthy age and gender-matched controls. Physical examination to determine blood pressure and waist circumference was carried out and so was sampling for plasma glucose, serum triglycerides, HDL-cholesterol and insulin. Insulin resistance was calculated by the HOMA-IR. Finally, subjects with and without metabolic syndrome were compared with controls (n=47), using one-way ANOVA for studying insulin resistance between groups, with Tukey's post-hoc comparison. The frequency of finding metabolic syndrome in cases of IGR remained 47%. The insulin resistance demonstrated stepwise worsening from control population (mean=1.54, 95 % CI: 1.77 - 2.37) to subjects suffering from only IGR (mean=2.07, 95 % CI: 1.77- 2.37) to metabolic syndrome (mean=2.67, 95 %, CI: 2.34 - 3.00) (p < 0.001). Patients with impaired glucose regulation may have significant insulin resistance. It is, thus, recommended that a vigorous search be made to measure insulin resistance in all cases diagnosed to have impaired glucose regulation. (author)

Decreased Plasma Nesfatin-1 Level Is Related to the Thyroid Dysfunction in Patients with Type 2 Diabetes Mellitus

Directory of Open Access Journals (Sweden)

Fupeng Liu

2014-01-01

Full Text Available Aims. Thyroid dysfunction is frequently observed in patients with type 2 diabetes mellitus (T2DM, but the underlying mechanism is still poorly understood. The present study aimed to investigate whether nesfatin-1 played a role in the thyroid dysfunction in patients with T2DM. Methods. 55 euthyroid patients were enrolled in this study including 30 patients with T2DM and 25 patients with impaired glucose regulation (IGR. 30 age-matched healthy people were also included as the control. The plasma levels of nesfatin-1, thyrotropin (TSH, and glycosylated hemoglobin (HbA1c as well as the body mass index (BMI were comparatively analyzed among the three groups. Results. The nesfatin-1 was significantly lower in patients with T2DM than in patients with IGR and in the control. On the contrary, the TSH level was significantly higher in patients with T2DM than in patients with IGR and in the control. Simple regression analysis showed that the plasma nesfatin-1 was negatively correlated with the TSH and HbA1c levels and positively correlated with the BMI. With multiple stepwise regression analysis, the nesfatin-1 remained to be independently correlated with the TSH, BMI, and HbA1c. Conclusions. The study was suggesting a role of nesfatin-1 in thyroid dysfunction in patients with T2DM.

[Life style interventions study on the effects of impaired glucose regulations in Shanghai urban communities].

Science.gov (United States)

Zhou, Jianjun

2011-05-01

To access the effects of life style interventions on impaired glucose regulation (IGR) in Shanghai urban communities, China. Two communities were randomly cluster-sampled to be carried out epidemiological intervention trial. Totally, 232 subjects with IGR were randomly allocated into 4 groups: control group,sports intervention group, diet intervention group, and sports and diet intervention group with the physical examinations in the baseline and end of this study respectively. Tests for fasting blood glucose, OGTT, HbA1c, total cholesterol,etc. were done. Data statistical analysis was occupied in SPSS 16.0. Compared to subjects of control group,fasting blood glucose, OGTT, HbAlc,total cholesterol,BMI,waist hip ratio and blood pressures were significantly decreased among subjects with three interventions (P intervention and sports and diet intervention (P intervention (P interventions groups (8.6% vs. 0, Fisher' s exact P = 0.002), and the rate of transferring into normal blood glucose levels (fasting blood glucose interventions group (3.4% vs. 8.6%, 14.0% and 16.9%, respectively) but only significant difference was observed between control group and sports and diet intervention group (OR = 5.74, 95% CI 1. 19-27. 64, P = 0.029). The life style interventions could decrease the risk of diabetes mellitus, help their transferring into normal blood glucose, and improve diabetic measures for the IGR population in Shanghai urban communities.

Defining the Core Genome of Salmonella enterica Serovar Typhimurium for Genomic Surveillance and Epidemiological Typing

Science.gov (United States)

Fu, Songzhe; Octavia, Sophie; Tanaka, Mark M.; Sintchenko, Vitali

2015-01-01

Salmonella enterica serovar Typhimurium is the most common Salmonella serovar causing foodborne infections in Australia and many other countries. Twenty-one S. Typhimurium strains from Salmonella reference collection A (SARA) were analyzed using Illumina high-throughput genome sequencing. Single nucleotide polymorphisms (SNPs) in 21 SARA strains ranged from 46 to 11,916 SNPs, with an average of 1,577 SNPs per strain. Together with 47 strains selected from publicly available S. Typhimurium genomes, the S. Typhimurium core genes (STCG) were determined. The STCG consist of 3,846 genes, a set that is much larger than that of the 2,882 Salmonella core genes (SCG) found previously. The STCG together with 1,576 core intergenic regions (IGRs) were defined as the S. Typhimurium core genome. Using 93 S. Typhimurium genomes from 13 epidemiologically confirmed community outbreaks, we demonstrated that typing based on the S. Typhimurium core genome (STCG plus core IGRs) provides superior resolution and higher discriminatory power than that based on SCG for outbreak investigation and molecular epidemiology of S. Typhimurium. STCG and STCG plus core IGR typing achieved 100% separation of all outbreaks compared to that of SCG typing, which failed to separate isolates from two outbreaks from background isolates. Defining the S. Typhimurium core genome allows standardization of genes/regions to be used for high-resolution epidemiological typing and genomic surveillance of S. Typhimurium. PMID:26019201

Effect of Triflumuron and Pyriproxyfen on Musca domestica L Larval Stages in the Laboratory

Directory of Open Access Journals (Sweden)

S Sulaiman

2008-08-01

Full Text Available Background:  The residual effect of triflumuron and pyriproxyfen on Musca domestica L larval stages was studied in the laboratory."n"nMethods: Both IGRs at varying concentrations ranging between 0.5 to 2.5 mg/L were placed inside beakers with mice chow and vitamin B complex and water as food for the 1st, 2nd and 3rd instars M.domestica larvae."n"nResults: Both IGRs inhibit M. domestica adult emergence of 98-98.5% when applied at the lowest concentration of 0.5 mg/L on the 1st instar, 93-97% of adult emergence inhibition on the 2nd instar,and 91-97% of adult emergence inhibi­tion on the 3rd instar larvae respectively. There was no significant difference between triflumuron and pyriproxy­fen on house­fly adult emergence inhibition when fed to the 1st, 2nd and 3rd instars M.domestica larvae (P> 0.05. However, there was a significant difference between the IGRs and the control (P< 0.05."n"nConclusion: Both triflumuron and pyriproxyfen are effective in inhibiting adult emergence of housefly M  domes­tica and therefore should be recommended for fly control particularly in chicken farms and dumping grounds in Malaysia for housefly control activities.

Molt disruption and mortality of Locusta migratoria var. manilensis ...

African Journals Online (AJOL)

Yomi

2012-02-23

Feb 23, 2012 ... use of broad-spectrum chemical pesticides, which can damage human health ... IGRs, including the chitin synthesis inhibitors (flufeno- xuron), plant-derived pesticides (swallowwort alkaloids and azadirachtin) (Xu, 2002; Cui ...

Susceptibilidade do besouro rola-bosta africano a reguladores de crescimento de insetos Susceptibility of African dung beetle to insect growth regulators

Directory of Open Access Journals (Sweden)

L.N. Domingues

2009-10-01

Full Text Available Verificou-se a ação dos reguladores de crescimento de insetos (IGR, diflubenzuron e methoprene, sobre o besouro rola-bosta africano, Digitonthophagus gazella (Fabricius, um inimigo natural da mosca-dos-chifres, Haematobia irritans irritans (Linnaeus. Casais de besouros foram colocados em baldes contendo terra úmida e alimentados com fezes bovinas contendo 1, 0,5 ou 0,2ppm de diflubenzuron e 0,2ppm de methoprene. Os insetos e sua prole foram recuperados com o auxílio de armadilhas pitfall. Diflubenzuron e methoprene não afetaram a sobrevivência dos adultos inicialmente expostos, mas interferiram na produção de descendentes. Diflubenzuron, nas concentrações de 1 e 0,5ppm, também afetou a duração do ciclo de vida dos besouros. Nenhum dos IGRs alterou a razão sexual dos descendentes obtidos. As concentrações testadas de diflubenzuron mostraram-se moderadamente nocivas ao besouro enquanto methoprene a 0,2ppm mostrou ser pouco nocivo, segundo os critérios da International Organization for Biological Control.The effects of insect growth regulators (IGR, diflubenzuron and methoprene, on African dung beetle, Digitonthophagus gazella (Fabricius, a natural enemy of the horn fly, Haematobia irritans irritans (Linnaeus, was studied. Beetles were placed in buckets partially filled with humid soil and were fed bovine feces containing 1, 0.5, or 0.2ppm diflubenzuron and 0.2ppm methoprene. Insects and their progenies were recovered by pitfall traps. Diflubenzuron and methoprene did not affect the survival of the adults but reduced their progenies. Diflubenzuron 1 and 0.5ppm also affected the life cicle of the beetles. None of the IGR modified the gender ratio of the progenies. According to the IOBC criteria, diflubenzuron tested concentrations showed to be moderately harmful to the beetles, whereas methoprene 0.2ppm was slightly harmful.

High-speed photometry of Gaia14aae: an eclipsing AM CVn that challenges formation models

Science.gov (United States)

Green, M. J.; Marsh, T. R.; Steeghs, D. T. H.; Kupfer, T.; Ashley, R. P.; Bloemen, S.; Breedt, E.; Campbell, H. C.; Chakpor, A.; Copperwheat, C. M.; Dhillon, V. S.; Hallinan, G.; Hardy, L. K.; Hermes, J. J.; Kerry, P.; Littlefair, S. P.; Milburn, J.; Parsons, S. G.; Prasert, N.; van Roestel, J.; Sahman, D. I.; Singh, N.

2018-05-01

AM CVn-type systems are ultracompact, hydrogen-deficient accreting binaries with degenerate or semidegenerate donors. The evolutionary history of these systems can be explored by constraining the properties of their donor stars. We present high-speed photometry of Gaia14aae, an AM CVn with a binary period of 49. 7 min and the first AM CVn in which the central white dwarf is fully eclipsed by the donor star. Modelling of the light curves of this system allows for the most precise measurement to date of the donor mass of an AM CVn, and relies only on geometric and well-tested physical assumptions. We find a mass ratio q = M2/M1 = 0.0287 ± 0.0020 and masses M1 = 0.87 ± 0.02 M⊙ and M2 = 0.0250 ± 0.0013 M⊙. We compare these properties to the three proposed channels for AM CVn formation. Our measured donor mass and radius do not fit with the contraction that is predicted for AM CVn donors descended from white dwarfs or helium stars at long orbital periods. The donor properties we measure fall in a region of parameter space in which systems evolved from hydrogen-dominated cataclysmic variables are expected, but such systems should show spectroscopic hydrogen, which is not seen in Gaia14aae. The evolutionary history of this system is therefore not clear. We consider a helium-burning star or an evolved cataclysmic variable to be the most likely progenitors, but both models require additional processes and/or fine-tuning to fit the data. Additionally, we calculate an updated ephemeris which corrects for an anomalous time measurement in the previously published ephemeris.

IPHAS J025827.88+635234.9 and IPHAS J051814.33+294113.0: Two probable eclipsing intermediate polars

Science.gov (United States)

Joshi, Arti; Pandey, Jeewan Chandra

2018-04-01

We present photometry in the R-band and linear polarimetry of two cataclysmic variables, namely IPHAS J025827.88 + 635234.9 and IPHAS J051814.33 + 294113.0. The data were obtained from 1-m class tele-scopes of the Aryabhatta Research Institute of Observational Sciences (ARIES; Nainital, India). In addition to the deep eclipse, strong short-period oscillations are also found. We derived a pulse period of (1203 ± 25) s for IPHAS J025827.88 + 635234.9 and (3277 ± 81) s for IPHAS J051814.33 + 294113.0. The presence of both orbital and spin modulations in these systems indicate that they belong to a class of intermediate polars. The full width at half depth of the eclipse is also found to be variable from epoch to epoch for IPHAS J025827.88 + 635234.9. The presence of a variable linear polarization of high value in these two sources indicates that these systems possess a strong magnetic field.

CCD Photometry Using Multiple Comparison Stars

Directory of Open Access Journals (Sweden)

Yonggi Kim

2004-09-01

Full Text Available The accuracy of CCD observations obtained at the Korean 1.8 m telescope has been studied. Seventeen comparison stars in the vicinity of the cataclysmic variable BG CMi have been measured. The ``artificial" star has been used instead of the ``control" star, what made possible to increase accuracy estimates by a factor of 1.3-2.1 times for ``good" and ``cloudy" nights, respectively. The algorithm of iterative determination of accuracy and weights of few comparison stars contributing to the artificial star, has been presented. The accuracy estimates for 13-mag stars are around 0.002 m mag for exposure times of 30 sec.

OV Bootis: Forty Nights of World-Wide Photometry (Abstract)

Science.gov (United States)

Patterson, J.; de Miguel, E.; Barret, D.; Brincat, S.; Boardman, J., Jr.; Buczynski, D.; Campbell, T.; Cejudo, D.; Cook, L.; Cook, M. J.; Collins, D.; Cooney, W.; Dubois, F.; Dvorak, S.; Halpern, J. P.; Kroes, A. J.; Lemay, D.; Licchelli, D.; Mankel, D.; Marshall, M.; Novak, R.; Oksanen, A.; Roberts, G.; Seargeant, J.; Sears, H.; Silcox, A.; Slauson, D.; Stone, G.; Thorstensen, J. R.; Ulowetz, J.; Vanmunster, T.; Wallgren, J.; Wood, M.

2017-12-01

(Abstract only) Among the 1000 known cataclysmic variables, only one appears to belong to the "Galactic halo"-the Population II stars. We report round-the-world photometry of this star (OV Boo) during March-April 2017, when it staged its first certified dwarf-nova outburst. The star is remarkable for its short binary period (66 minutes), high proper motion, metal-poor composition, substellar secondary, sharp white-dwarf eclipses, and nonradial pulsations. Something for everybody - and it even had the good manners to erupt in northern springtime, when it transits near local midnight. Move over, SS Cyg and WZ Sge; there's a new celebrity in town!

How to Model Super-Soft X-ray Sources?

Science.gov (United States)

Rauch, Thomas

2012-07-01

During outbursts, the surface temperatures of white dwarfs in cataclysmic variables exceed by far half a million Kelvin. In this phase, they may become the brightest super-soft sources (SSS) in the sky. Time-series of high-resolution, high S/N X-ray spectra taken during rise, maximum, and decline of their X-ray luminosity provide insights into the processes following such outbursts as well as in the surface composition of the white dwarf. Their analysis requires adequate NLTE model atmospheres. The Tuebingen Non-LTE Model-Atmosphere Package (TMAP) is a powerful tool for their calculation. We present the application of TMAP models to SSS spectra and discuss their validity.

QPOs in CVs: An executive summary

Science.gov (United States)

Warner, Brian; Woudt, Patrick A.

2008-09-01

An overview is given of the properties of the various kinds of quasi-periodic luminosity modulations observed in cataclysmic variables (CVs). The two principal types, known in the CV literature as dwarf nova oscillations and quasi-periodic oscillations, have similarities to the high and low frequency quasi-periodic oscillations in X-Ray binaries. There is a further well observed class known as longer period dwarf nova oscillations. In CVs the observed interrelations between these oscillations suggests a model of magnetically controlled accretion onto a rapidly rotating equatorial belt of accreted gas. Non-radial oscillations of the central white dwarf are observed in some systems.

Comparative study in LTC Combustion between a short HP EGR loop without cooler and a variable lift and duration system

Energy Technology Data Exchange (ETDEWEB)

Bression, Guillaume; Pacaud, Pierre; Soleri, Dominique; Cessou, Jerome [IFP (France); Azoulay, David [Renault Powertrain Div. (France); Lawrence, David [Mechadyne (United Kingdom); Doradoux, Laurent; Guerrassi, Noureddine [Delphi Diesel Systems (France)

2008-07-01

In order to reach future Diesel emission standards such as Euro 6 or Tier 2 Bin 5, NO{sub x} emissions need to be dramatically reduced. Advanced technologies and engine settings such as higher EGR rates, reduced compression ratio, EGR cooler and low-pressure EGR loop - depending on vehicle application - may help to reach this target whilst maintaining low CO{sub 2} emissions and fuel consumption. However, the resulting low combustion temperatures and the low air-fuel ratios lead to a significant increase in HC and CO emissions, especially during the start-up phase prior to catalyst light-off. Moreover, high levels of EGR make transient operation even more difficult. So HC-CO emissions and EGR transient operation represent two key issues that could limit the extension of this alternative combustion mode. Consequently, an in-depth investigation of a variable lift and duration (VLD) system was performed to overcome these problems on a 4-cylinder engine, which was also equipped with a dual HP-LP EGR loop. The VLD system tested in this paper produces a variable camshaft-operated exhaust valve re-opening, which is controlled by a hydraulic rotary actuator, ensuring quick and accurate regulation of the internal gas recirculation (IGR). By increasing gas temperature in the combustion chamber, this advanced technology allows us to reduce HC-CO emissions by 50% under 3 bar BMEP. Although efficient, this technology has to be compared with other solutions from a cost-to-value point of view. The aim of this paper is firstly to compare the double lift exhaust system with a short route high-performance EGR loop without cooler by quantifying their respective gains on steady state points of the NEDC cycle, then by evaluating their potential performances during transient conditions. With the short-route EGR, the potential in HC-CO emission reduction remains significant on a large scale of engine temperatures representative of engine warm up. However, the VLD system allows us to

Identification of candidate structured RNAs in the marine organism 'Candidatus Pelagibacter ubique'

Directory of Open Access Journals (Sweden)

Schwalbach Michael S

2009-06-01

Full Text Available Abstract Background Metagenomic sequence data are proving to be a vast resource for the discovery of biological components. Yet analysis of this data to identify functional RNAs lags behind efforts to characterize protein diversity. The genome of 'Candidatus Pelagibacter ubique' HTCC 1062 is the closest match for approximately 20% of marine metagenomic sequence reads. It is also small, contains little non-coding DNA, and has strikingly low GC content. Results To aid the discovery of RNA motifs within the marine metagenome we exploited the genomic properties of 'Cand. P. ubique' by targeting our search to long intergenic regions (IGRs with relatively high GC content. Analysis of known RNAs (rRNA, tRNA, riboswitches etc. shows that structured RNAs are significantly enriched in such IGRs. To identify additional candidate structured RNAs, we examined other IGRs with similar characteristics from 'Cand. P. ubique' using comparative genomics approaches in conjunction with marine metagenomic data. Employing this strategy, we discovered four candidate structured RNAs including a new riboswitch class as well as three additional likely cis-regulatory elements that precede genes encoding ribosomal proteins S2 and S12, and the cytoplasmic protein component of the signal recognition particle. We also describe four additional potential RNA motifs with few or no examples occurring outside the metagenomic data. Conclusion This work begins the process of identifying functional RNA motifs present in the metagenomic data and illustrates how existing completed genomes may be used to aid in this task.

Cardiometabolic Risk in Hyperlipidemic Men and Women

Directory of Open Access Journals (Sweden)

Michael Leutner

2016-01-01

Full Text Available Objective. The aim of this study was to evaluate sex specific differences of metabolic and clinical characteristics of treated hyperlipidemic men and women (HL-men and HL-women. Methods. In this study vascular and metabolic characteristics of 35 HL-women and 64 HL-men were assessed. In addition a sex specific analysis of metabolic and nutritional habits of HL-patients with prediabetes (HL-IGR was done. Results. HL-women were older and had favourable concentrations of high density lipoprotein cholesterol (HDL-cholesterol, triglycerides (TG, and triglyceride/HDL-cholesterol ratio (TG/HDL-ratio but were also shown to have higher concentrations of lipoprotein-a compared to HL-men. HL-men were characterized as having higher levels of liver-specific parameters and body weight as well as being more physically active compared to HL-women. Brain natriuretic peptide (pro-BNP was higher in HL-women than HL-men, while no differences in metabolic syndrome and glycemic parameters were shown. HL-IGR-women were also older and still had a better profile of sex specific lipid parameters, as well as a lower body weight compared to HL-IGR-men. No differences were seen in vascular parameters such as the intima media thickness (IMT. Conclusion. HL-women were older and had overall more favourable concentrations of lipid parameters and liver enzymes but did not differ regarding vascular morphology and insulin sensitivity compared to HL-men of comparable body mass index (BMI.

A new stochastic model considering satellite clock interpolation errors in precise point positioning

Science.gov (United States)

Wang, Shengli; Yang, Fanlin; Gao, Wang; Yan, Lizi; Ge, Yulong

2018-03-01

Precise clock products are typically interpolated based on the sampling interval of the observational data when they are used for in precise point positioning. However, due to the occurrence of white noise in atomic clocks, a residual component of such noise will inevitable reside within the observations when clock errors are interpolated, and such noise will affect the resolution of the positioning results. In this paper, which is based on a twenty-one-week analysis of the atomic clock noise characteristics of numerous satellites, a new stochastic observation model that considers satellite clock interpolation errors is proposed. First, the systematic error of each satellite in the IGR clock product was extracted using a wavelet de-noising method to obtain the empirical characteristics of atomic clock noise within each clock product. Then, based on those empirical characteristics, a stochastic observation model was structured that considered the satellite clock interpolation errors. Subsequently, the IGR and IGS clock products at different time intervals were used for experimental validation. A verification using 179 stations worldwide from the IGS showed that, compared with the conventional model, the convergence times using the stochastic model proposed in this study were respectively shortened by 4.8% and 4.0% when the IGR and IGS 300-s-interval clock products were used and by 19.1% and 19.4% when the 900-s-interval clock products were used. Furthermore, the disturbances during the initial phase of the calculation were also effectively improved.

Molt disruption and mortality of Locusta migratoria var. manilensis ...

African Journals Online (AJOL)

IGRs) on the oriental migratory locust Locusta migratoria var. manilensis were assessed. Under laboratory conditions, at the highest tested dose rate of 300 ppm, the percent mortality and molt inhibition after two weeks for the five tested ...

AMPA receptor ligands

DEFF Research Database (Denmark)

Strømgaard, Kristian; Mellor, Ian

2004-01-01

Alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors (AMPAR), subtype of the ionotropic glutamate receptors (IGRs), mediate fast synaptic transmission in the central nervous system (CNS), and are involved in many neurological disorders, as well as being a key player in the f......Alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) receptors (AMPAR), subtype of the ionotropic glutamate receptors (IGRs), mediate fast synaptic transmission in the central nervous system (CNS), and are involved in many neurological disorders, as well as being a key player...... in the formation of memory. Hence, ligands affecting AMPARs are highly important for the study of the structure and function of this receptor, and in this regard polyamine-based ligands, particularly polyamine toxins, are unique as they selectively block Ca2+ -permeable AMPARs. Indeed, endogenous intracellular...

Variability Bugs:

DEFF Research Database (Denmark)

Melo, Jean

. Although many researchers suggest that preprocessor-based variability amplifies maintenance problems, there is little to no hard evidence on how actually variability affects programs and programmers. Specifically, how does variability affect programmers during maintenance tasks (bug finding in particular......)? How much harder is it to debug a program as variability increases? How do developers debug programs with variability? In what ways does variability affect bugs? In this Ph.D. thesis, I set off to address such issues through different perspectives using empirical research (based on controlled...... experiments) in order to understand quantitatively and qualitatively the impact of variability on programmers at bug finding and on buggy programs. From the program (and bug) perspective, the results show that variability is ubiquitous. There appears to be no specific nature of variability bugs that could...

Aperture synthesis observations of solar and stellar radio emission

International Nuclear Information System (INIS)

Bastian, T.S.

1987-01-01

The work presented in this thesis relied upon the radio astronomical instrument, The Very Large Array. The thesis is divided into three major sections. In the first the author applied maximum entropy-type image reconstruction techniques, using both single dish and iterferometer data, to generate full disk images of the Sun at a wavelength λ ∼ 21 cm. Using a set of six such images obtained during the Sun's decline from sunspot maximum to minimum, he has noted a number of previously unreported phenomena. Among these: (1) a systematic decrease in quiet Sun's brightness temperature as it declined to minimum; (2) a systematic decrease in the Sun's radius at 21 cm; (3) evidence for the evolution of polar coronal holes during the course of the solar cycle. The observed variation, though not noted previously at radio wavelengths, is entirely consistent with white light K coronagraph data. The results reported here explain the conflicting nature of a number of past observations. In the second section of the thesis, he presents the results of a long term survey of magnetic cataclysmic variables (CVs). Cataclysmic variables are close binary systems which contain a white dwarf accreting mass from a late-type secondary, typically a dwarf of spectral type, G, K, or M. The survey resulted in the detection of two out of the eighteen systems observed. In the third section of the thesis, he presents new results on flare stars in the solar neighborhood and in the Pleiades. He has successfully employed the technique of dynamic spectroscopy to constrain the mechanisms(s) for radio flaring on other stars. The second part of section three is devoted to a search for radio emission from flare stars in the Pleiades which was motivated by the evolutionary questions raised by flare stars and the Pleiades lower main sequence

IGRA BEKA-ORGANIZATORA IGRE U NAPADU

Directory of Open Access Journals (Sweden)

Miodrag Kocić

2005-04-01

Full Text Available A basketball team can be regarded as a small group with its own system of roles, tasks and obligations defined in advance according to which duties and rights of every member of the team are allocated. Every team is in need of a leader. The results of a team depend to a great extent on a good leadership. Nowadays the efficiency of the whole team depends on the efficiency of the guards. Being the organizer of the game a guard is actually its catalyst; he dictates the rhythm, makes the decisions about organizing counterattack and semi counterattack. All this decision-making and organizing demand certain qualities in an organizer that should be closely analyzed. That is, all the factors of the success in basketball such as mobility, situational mobility, functional and cognitive abilities and conative characteristics should be paid special attention to. Good counter- and positional attack depend to a great extent to the technical and tactical maneuvers of the guards. Without good passing, game review and tactical knowledge there cannot be good coordination among the players, which is the necessary prerequisite for easy scoring

NuSTAR and swift observations of the fast rotating magnetized white dwarf AE Aquarii

DEFF Research Database (Denmark)

Kitaguchi, Takao; An, Hongjun; Beloborodov, Andrei M.

2014-01-01

AE Aquarii is a cataclysmic variable with the fastest known rotating magnetized white dwarf (P-spin = 33.08 s). Compared to many intermediate polars, AE Aquarii shows a soft X-ray spectrum with a very low luminosity (L-X similar to 10(31) erg s(-1)). We have analyzed overlapping observations...... of this system with the NuSTAR and the Swift X-ray observatories in 2012 September. We find the 0.5-30 keV spectra to be well fitted by either an optically thin thermal plasma model with three temperatures of 0.75(-0.45)(+0.18), 2.29(-0.82)(+0.96), and 9.33(-2.18)(+6.07) keV, or an optically thin thermal plasma...

High Time Resolution Astrophysics

CERN Document Server

Phelan, Don; Shearer, Andrew

2008-01-01

High Time Resolution Astrophysics (HTRA) is an important new window to the universe and a vital tool in understanding a range of phenomena from diverse objects and radiative processes. This importance is demonstrated in this volume with the description of a number of topics in astrophysics, including quantum optics, cataclysmic variables, pulsars, X-ray binaries and stellar pulsations to name a few. Underlining this science foundation, technological developments in both instrumentation and detectors are described. These instruments and detectors combined cover a wide range of timescales and can measure fluxes, spectra and polarisation. These advances make it possible for HTRA to make a big contribution to our understanding of the Universe in the next decade.

New Observations of the Old Magnetic Nova GQ Muscae

Directory of Open Access Journals (Sweden)

Narloch W.

2014-03-01

Full Text Available Photometric observations of GQ Mus performed between 1992 and 2011 are reported. We find that the total amplitude of the orbital modulation of its brightness decreased from ~ 0.9 mag in 1992 to ~ 0.2 mag in 2010, becoming comparable to the amplitude of chaotic flickering on a time scale of several minutes. Optical spectra obtained in 2001 and 2012 indicate continuing activity of GQ Mus. The spectra show broad emission lines of He II and H I typical for magnetic cataclysmic variables. The nova was found to be an UV-bright object in 2001 and 2012. We also show that the orbital period of GQ Mus has been constant between 1989 and 2010–2011.

Superoutburst of a New Sub-Period-Minimum Dwarf Nova CSS130418 in Hercules

Directory of Open Access Journals (Sweden)

D. Chochol

2015-02-01

Full Text Available Multicolour photometry of a new dwarf nova CSS130418 in Hercules, which underwent superoutburst on April 18, 2013, allow to classified it as a WZ Sge-type dwarf nova. The phase light curves for different stages of superoutburst are presented. The early superhumps were used to determine the orbital period Porb = 64.84(1 minutes, which is shorter than the period minimum ~78 minutes for normal hydrogen-rich cataclysmic variables. We found the mean period of ordinary superhumps Psh = 65.559(1 minutes. The quiescent spectrum is rich in helium, showing double peaked emissionlines of H I and He I from accretion disk, so the dwarf nova is in a late stage of stellar evolution.

Spectral types for objects in the Kiso survey. IV - Data for 81 stars

Science.gov (United States)

Wegner, Gary; Mcmahan, Robert K.

1988-01-01

Spectroscopy and spectral types for 81 ultraviolet-excess objects found in the Kiso Schmidt-camera survey are reported. The data were secured with the McGraw-Hill 1.3 m telescope at 8-A resolution covering the wavelength interval 4000 -7200 A using the Mark II spectrograph. Descriptions of the spectra of some of the more peculiar objects found in this sample are given and include 14 sub-dwarfs, 23 definite DA white dwarfs, including a magnetic one, and one DQ whie dwarf, eight quasars and emission-line objects, and a new composite DA + dM system. More spectroscopy of the new cataclysmic variable KUV 01584-0939 and a possibly related object is also described.

Collapse of white dwarfs in low mass binary systems

International Nuclear Information System (INIS)

Isern, J.; Canal, R.; Garcia-Berro, E.; Hernanz, M.; Labay, J.

1987-01-01

Low-mass binary X-ray sources and cataclysmic variables are composed of a compact star plus a non-degenerate star with a mass of the order of 1 M sun . In the first case, the degenerate star is a neutron star. In the second case, the star is a white dwarf. The similarities of both systems are so high that it is worthwhile to look for the possibility of obtaining a neutron star from the collapse of a white dwarf that accretes matter. The present work shows that massive, initially cold white dwarfs can collapse non-explosively if they accrete mass at a rate greater than 1.0E-7 M sun per year. (Author)

Hubble Space Telescope Ultraviolet Light Curves Reveal Interesting Properties of CC Sculptoris and RZ Leonis

Energy Technology Data Exchange (ETDEWEB)

Szkody, Paula; Mukadam, Anjum S. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Toloza, Odette; Gänsicke, Boris T.; Pala, Anna F. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Dai, Zhibin [Yunnan Observatories, Chinese Academy of Sciences, 396 Yangfangwang, Guandu District, Kunming, 650216 (China); Waagen, Elizabeth O. [AAVSO, 48 Bay State Rd, Cambridge, MA 02138 (United States); Godon, Patrick; Sion, Edward M., E-mail: szkody@astro.washington.edu [Department of Astrophysics and Planetary Science, Villanova University, Villanova, PA 19085 (United States)

2017-03-01

Time-tag ultraviolet data obtained on the Hubble Space Telescope in 2013 reveal interesting variability related to the white dwarf spin in the two cataclysmic variables RZ Leo and CC Scl. RZ Leo shows a period at 220 s and its harmonic at 110 s, thus identifying it as a likely Intermediate Polar (IP). The spin signal is not visible in a short single night of ground-based data in 2016, but the shorter exposures in that data set indicate a possible partial eclipse. The much larger UV amplitude of the spin signal in the known IP CC Scl allows the spin of 389 s, previously only seen at outburst, to be visible at quiescence. Spectra created from the peaks and troughs of the spin times indicate a hotter temperature of several thousand degrees during the peak phases, with multiple components contributing to the UV light.

Individual Movement Variability Magnitudes Are Explained by Cortical Neural Variability.

Science.gov (United States)

Haar, Shlomi; Donchin, Opher; Dinstein, Ilan

2017-09-13

Humans exhibit considerable motor variability even across trivial reaching movements. This variability can be separated into specific kinematic components such as extent and direction that are thought to be governed by distinct neural processes. Here, we report that individual subjects (males and females) exhibit different magnitudes of kinematic variability, which are consistent (within individual) across movements to different targets and regardless of which arm (right or left) was used to perform the movements. Simultaneous fMRI recordings revealed that the same subjects also exhibited different magnitudes of fMRI variability across movements in a variety of motor system areas. These fMRI variability magnitudes were also consistent across movements to different targets when performed with either arm. Cortical fMRI variability in the posterior-parietal cortex of individual subjects explained their movement-extent variability. This relationship was apparent only in posterior-parietal cortex and not in other motor system areas, thereby suggesting that individuals with more variable movement preparation exhibit larger kinematic variability. We therefore propose that neural and kinematic variability are reliable and interrelated individual characteristics that may predispose individual subjects to exhibit distinct motor capabilities. SIGNIFICANCE STATEMENT Neural activity and movement kinematics are remarkably variable. Although intertrial variability is rarely studied, here, we demonstrate that individual human subjects exhibit distinct magnitudes of neural and kinematic variability that are reproducible across movements to different targets and when performing these movements with either arm. Furthermore, when examining the relationship between cortical variability and movement variability, we find that cortical fMRI variability in parietal cortex of individual subjects explained their movement extent variability. This enabled us to explain why some subjects

The Effects of Oral Application of Cyromazine and Triflumuron on House-Fly Larvae

Directory of Open Access Journals (Sweden)

B Vazirianzadeh

2007-12-01

Full Text Available Accumulations of large quantities of wastes (manure, used litter, dead birds which are excellent medium for fly-larvae over poultry houses provide breeding places for different groups of fly pests, with house-flies being the dominant species. This project is a comparative lab study. In this research project the larvicidal effects of cyromazine and triflumuron were studied as two Insect Growth Regulators (IGRs to reduce the fly population using oral application. Both IGRs had a signifi-cant effect on larval mortality compared with their controls among the concentrations (P< 0.01, Fisher's LSD with Bonf-feroni correction including a dose-dependent relationship. Comparisons among LC50 and LC90 values, using fiducial limits, showed that cyromazine was significantly more toxic to the larvae of the two strains than triflumuron. It is concluded that cyromazine should be used in a larvicidal programme to control house-fly rather than triflumuron.

Green-Roof Effects on Neighborhood Microclimate and Human Thermal Sensation

Directory of Open Access Journals (Sweden)

C. Y. Jim

2013-01-01

Full Text Available Green roofs have been recognized as an effective sustainable design tool to mitigate urban heat island (UHI effects. Previous studies have identified green-roof benefits in cooling and energy-conservation at the building scale, with limited exploration of the wider influence on neighborhood microclimate and human thermal comfort (HTC. This paper investigated the impacts of community-scale green-roof installation on air temperature and HTC in five typical residential neighborhoods of subtropical Hong Kong. The microclimate models ENVI-met and RayMan permitted studies of two main green-roof scenarios, namely extensive (EGR and intensive (IGR. Microclimatic monitoring data from a local experimental green-roof site validated the modeling methods. The results verified that green-roof cooling effects were not restricted to rooftops, but extended to the ground to improve neighborhood microclimate. EGR reduced pedestrian-level air temperature by 0.4–0.7 °C, and IGR by 0.5–1.7 °C, with maximum effect in open-set low rise sites. Coverage by building footprints and building height dampened lateral and vertical advection of cool air generated by green roofs. Roof greening also improved notably the rooftop-podium level HTC. Diurnal duration of high heat stress was reduced by 6–9 h for EGR scenarios, and 9–11 h for IGR. The findings indicated that large-scale green-roof installation could bring neighborhood-wide cooling, mitigate urban heat island effect, and furnish more comfortable thermal environment for urban residents.

Are we getting healthier as we grow older? Implications for babyboomer labor force participation.

Science.gov (United States)

Schofield, Deborah J; Passey, Megan E; Earnest, Arul; Gloor, Ian C; Shrestha, Rupendra

2007-10-01

The Intergenerational Report (IGR) released by the Department of the Treasury of the Commonwealth of Australia in 2002 highlighted pressures that in the future would threaten the sustainability of the Australian government's budget balance. These pressures result from the growing needs of an aging population and labor shortages that will limit economic growth and taxation revenue. The IGR has become a driving force in planning government policy. The Treasurer has recently said that "the whole economic agenda of the government at the moment is drawn from the IGR." In response, the Prime Minster and Treasurer have promoted deferred or gradual retirement as part of the solution. However, about 50% of men and 20% of women retire early as a result of ill health, indicating that poor health is potentially a limiter of economic growth. This paper reports lower labor force participation among persons with poorer health and that these persons move out of the labor force at a faster rate as they age. A range of measures suggests some decline in health in the pre-retirement age group (those aged from 40 to 64 years). This indicates that better health may be a facilitator of greater labor force participation in the baby boomer cohort. However, there is evidence that improving economic conditions in Australia leading to low unemployment has created an environment more favorable to the employment of older workers with health problems as there has been a rise in labor force participation in these groups, and measures to prevent chronic disease may further increase the employment prospects.

Impact of night sleep duration on glycemic and triglyceride levels in Chinese with different glycemic status.

Science.gov (United States)

Zheng, Yu; Wang, Anping; Pan, Changyu; Lu, Juming; Dou, Jingtao; Lu, Zhaohui; Ba, Jianming; Wang, Baoan; Mu, Yiming

2015-01-01

The aim of the present study was to assess the relationship between night sleep duration and glycemic and triglyceride (TG) levels among people with different glycemic status. In all, 18,121 subjects aged ≥40 years were enrolled in this cross-sectional study, including 4318 with impaired glucose regulation (IGR), 4225 with diabetes, and 9578 with normal glucose regulation (NGR). The IGR + diabetes and NGR groups were divided into three subgroups according to self-reported night sleep duration as follows: (i) 9 h. The associations of sleep duration with HbA1c, fasting plasma glucose (FPG), 2-h post-load plasma glucose (PPG), and TG levels were examined. Long night sleep duration (>9 h) was associated with higher HbA1c, FPG, PPG, and TG levels compared with sleep duration of 6-9 h (P index and depressive symptoms, and remained significant even after adjusting for snoring. A significant interaction between sleep duration and TG or snoring was observed for HbA1c levels, which attenuated the sleep-HbA1c association in the IGR + diabetes group. However, no significant association was observed between short night sleep duration and HbA1c levels. Long night sleep duration is associated with higher HbA1c, FPG, PPG, and TG levels in IGR and diabetes patients, independent of potential confounders. This may be important in clinical management of IGR and diabetes patients. © 2014 Ruijin Hospital, Shanghai Jiaotong University School of Medicine and Wiley Publishing Asia Pty Ltd.

Human skin-derived fibroblasts used as a 'Trojan horse' for drug delivery.

Science.gov (United States)

Coccè, V; Vitale, A; Colombo, S; Bonomi, A; Sisto, F; Ciusani, E; Alessandri, G; Parati, E; Brambilla, P; Brambilla, M; La Porta, C A; Pessina, A

2016-06-01

Drug toxicity currently represents the main challenge of tumour chemotherapy. Our group recently developed a new method for drug delivery inspired by the 'Trojan Horse' concept. Human mesenchymal stem cells (hMSCs) have been shown to play the role of new 'horses' in delivering anti-tumour agents, without involving any genetic manipulation. As human stromal dermal fibroblasts (hSDFs) represent an interesting alternative to hMSCs, being easy to isolate, they could be an ideal candidate for this kind of procedure. To investigate whether hSDFs can take up and deliver paclitaxel (PTX) in sufficient concentrations to inhibit a very aggressive melanoma tumour (IgR39) in vitro. hSDFs were primed with high doses of PTX, and then the effect of drug delivery on IgR39 melanoma proliferation in vitro was evaluated using several assays (antiproliferation, transwell cocultures, rosette assays and colony growth assays). Furthermore, the cell cycle and PTX uptake/release mechanism of hSDFs were studied both under both normal and hypoxic conditions. hSDFs incorporated PTX and then released it with unaffected pharmacological activity, inhibiting human IgR39 melanoma growth in vitro. The hypoxic conditions did not induce changes in cell cycle pattern and the uptake-release mechanism with PTX was not affected. hSDFs can be used as a Trojan horse, as the released drug was functionally active. These results indicated that these cells could be used for clinical treatment as the drug was released into the cellular environment and the primed cells underwent apoptosis. © 2016 British Association of Dermatologists.

Statistical variability of hydro-meteorological variables as indicators ...

African Journals Online (AJOL)

Statistical variability of hydro-meteorological variables as indicators of climate change in north-east Sokoto-Rima basin, Nigeria. ... water resources development including water supply project, agriculture and tourism in the study area. Key word: Climate change, Climatic variability, Actual evapotranspiration, Global warming ...

Susceptibility of selected stored product insects to a combination treatment of pyriproxyfen and novaluron

Science.gov (United States)

A series of tests was conducted to evaluate susceptibility of Tribolium castaneum (Herbst), the red flour beetle, Trogoderma variabile (Ballion), the warehouse beetle, and Dermestes maculatus (DeGeer), the hide beetle, to a new insecticide (Tekko®) which contained the IGR pyreproxyfen and the chiten...

Residual efficacy of pyriproxyfen and Hydroprene applied to wood, metal, and concrete for control of stored-product insects

Science.gov (United States)

Pyriproxyfen and hydroprene are insect growth regulators (IGRs) that have been evaluated to control insect pests of field crops, but there are limited reports of efficacy against stored-product insects. A laboratory study was conducted to determine residual efficacy of pyriproxyfen and hydroprene on...

Short timescale 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

2006-01-01

We present the V-band variability analysis of the Faint Sky Variability Survey (FSVS). The FSVS combines colour and time variability information, from timescales of 24 minutes to tens of days, down to V = 24. We find that �1% of all point sources are variable along the main sequence reaching �3.5%

Supersoft X-Ray Source CAL 83: A Possible AE Aqr-like System

Directory of Open Access Journals (Sweden)

A. Odendaal

2015-02-01

Full Text Available CAL83 is a close binary supersoft X-ray source in the Large Magellanic Cloud. A ~67 s periodicity detected in supersoft X-rays is most probably associated with the spin period of a highly spun-up white dwarf (WD. The variability in the period is ascribed to the obscuration of the WD by the hydrogen burning envelope surrounding it, rotating with a period that is close to, but not quite synchronized with, the WD rotation period. Optical spectra obtained with SALT exhibit accretion disc emission lines with broad wing structures and P Cyg profiles, indicating mass outflows. Timing analysis of photometrical observations performed at the South African Astronomical Observatory (SAAO revealed variable signals at ≤1 mHz which are thought to be associated with quasi-periodic oscillations from an accretion disc. The short spin period inferred for CAL83 can be the result of spin-up by accretion disc torques during a long mass transfer history, placing this source on a similar evolutionary track as the cataclysmic variable AE Aqr.

Healthcare hashtag index development: Identifying global impact in social media.

Science.gov (United States)

Pinho-Costa, Luís; Yakubu, Kenneth; Hoedebecke, Kyle; Laranjo, Liliana; Reichel, Christofer Patrick; Colon-Gonzalez, Maria Del C; Neves, Ana Luísa; Errami, Hassna

2016-10-01

Create an index of global reach for healthcare hashtags and tweeters therein, filterable by topic of interest. For this proof-of-concept study we focused on the field of Primary Care and Family Medicine. Six hashtags were selected based on their importance, from the ones included in the 'Healthcare Hashtag Project'. Hashtag Global Reach (HGR) was calculated using the additive aggregation of five weighted, normalized indicator variables: number of impressions, tweets, tweeters, user locations, and user languages. Data were obtained for the last quarter of 2014 and first quarter of 2015 using Symplur Signals. Topic-specific HGR were calculated for the top 10 terms and for sets of quotes mapped after a thematic analysis. Individual Global Reach, IGR, was calculated across hashtags as additive indexes of three indicators: replies, retweets and mentions. Using the HGR score we were able to rank six selected hashtags and observe their performance throughout the study period. We found that #PrimaryCare and #FMRevolution had the highest HGR score in both quarters; interestingly, #FMChangeMakers experienced a marked increase in its global visibility during the study period. "Health Policy" was the commonest theme, while "Care", "Family" and "Health" were the most common terms. This is the first study describing an altmetric hashtag index. Assuming analytical soundness, the Index might prove generalizable to other healthcare hashtags. If released as a real-time business intelligence tool with customizable settings, it could aid publishing and strategic decisions by netizens, organizations, and analysts. IGR could also serve to augment academic evaluation and professional development. Our study demonstrates the feasibility of using an index on the global reach of healthcare hashtags and tweeters. Copyright © 2016 Elsevier Inc. All rights reserved.

All varieties of encoding variability are not created equal: Separating variable processing from variable tasks

Science.gov (United States)

Huff, Mark J.; Bodner, Glen E.

2014-01-01

Whether encoding variability facilitates memory is shown to depend on whether item-specific and relational processing are both performed across study blocks, and whether study items are weakly versus strongly related. Variable-processing groups studied a word list once using an item-specific task and once using a relational task. Variable-task groups’ two different study tasks recruited the same type of processing each block. Repeated-task groups performed the same study task each block. Recall and recognition were greatest in the variable-processing group, but only with weakly related lists. A variable-processing benefit was also found when task-based processing and list-type processing were complementary (e.g., item-specific processing of a related list) rather than redundant (e.g., relational processing of a related list). That performing both item-specific and relational processing across trials, or within a trial, yields encoding-variability benefits may help reconcile decades of contradictory findings in this area. PMID:25018583

The Federal-state Intergovernmental Relationship in Ethiopia:

African Journals Online (AJOL)

Nigussie_Afesha

framework is thus essential to optimize the role of IGR in the Ethiopian federal ... legal, financial and administrative matters and policy coordination. ..... Informal Power Resources of the Regional Chief Executives in Russian center- .... 81 Interview with Ato Mebeiratu Belay, policy analysis and plan officer, Addis Ababa, Feb.

The Effects of Oral Application of Cyromazine and Triflumuron on House-Fly Larvae

Directory of Open Access Journals (Sweden)

B Vazirianzadeh

2007-11-01

Full Text Available Accumulations of large quantities of wastes (manure, used litter, dead birds which are excellent medium for fly-larvae over poultry houses provide breeding places for different groups of fly pests, with house-flies being the dominant species. This project is a comparative lab study. In this research project the larvicidal effects of cyromazine and triflumuron were studied as two Insect Growth Regulators (IGRs to reduce the fly population using oral application. Both IGRs had a signifi-cant effect on larval mortality compared with their controls among the concentrations (P< 0.01, Fisher's LSD with Bonf-feroni correction including a dose-dependent relationship. Comparisons among LC50 and LC90 values, using fiducial limits, showed that cyromazine was significantly more toxic to the larvae of the two strains than triflumuron. It is concluded that cyromazine should be used in a larvicidal programme to control house-fly rather than triflumuron.

LOW-FREQUENCY QUASI-PERIODIC OSCILLATION FROM THE 11 Hz ACCRETING PULSAR IN TERZAN 5: NOT FRAME DRAGGING

International Nuclear Information System (INIS)

Altamirano, D.; Van der Klis, M.; Wijnands, R.; Ingram, A.; Linares, M.; Homan, J.

2012-01-01

We report on six RXTE observations taken during the 2010 outburst of the 11 Hz accreting pulsar IGR J17480–2446 located in the globular cluster Terzan 5. During these observations we find power spectra which resemble those seen in Z-type high-luminosity neutron star low-mass X-ray binaries, with a quasi-periodic oscillation (QPO) in the 35-50 Hz range simultaneous with a kHz QPO and broadband noise. Using well-known frequency-frequency correlations, we identify the 35-50 Hz QPOs as the horizontal branch oscillations, which were previously suggested to be due to Lense-Thirring (LT) precession. As IGR J17480–2446 spins more than an order of magnitude more slowly than any of the other neutron stars where these QPOs were found, this QPO cannot be explained by frame dragging. By extension, this casts doubt on the LT precession model for other low-frequency QPOs in neutron stars and perhaps even black hole systems.

Low-frequency Quasi-periodic Oscillation from the 11 Hz Accreting Pulsar in Terzan 5: Not Frame Dragging

Science.gov (United States)

Altamirano, D.; Ingram, A.; van der Klis, M.; Wijnands, R.; Linares, M.; Homan, J.

2012-11-01

We report on six RXTE observations taken during the 2010 outburst of the 11 Hz accreting pulsar IGR J17480-2446 located in the globular cluster Terzan 5. During these observations we find power spectra which resemble those seen in Z-type high-luminosity neutron star low-mass X-ray binaries, with a quasi-periodic oscillation (QPO) in the 35-50 Hz range simultaneous with a kHz QPO and broadband noise. Using well-known frequency-frequency correlations, we identify the 35-50 Hz QPOs as the horizontal branch oscillations, which were previously suggested to be due to Lense-Thirring (LT) precession. As IGR J17480-2446 spins more than an order of magnitude more slowly than any of the other neutron stars where these QPOs were found, this QPO cannot be explained by frame dragging. By extension, this casts doubt on the LT precession model for other low-frequency QPOs in neutron stars and perhaps even black hole systems.

Concurrent variable-interval variable-ratio schedules in a dynamic choice environment.

Science.gov (United States)

Bell, Matthew C; Baum, William M

2017-11-01

Most studies of operant choice have focused on presenting subjects with a fixed pair of schedules across many experimental sessions. Using these methods, studies of concurrent variable- interval variable-ratio schedules helped to evaluate theories of choice. More recently, a growing literature has focused on dynamic choice behavior. Those dynamic choice studies have analyzed behavior on a number of different time scales using concurrent variable-interval schedules. Following the dynamic choice approach, the present experiment examined performance on concurrent variable-interval variable-ratio schedules in a rapidly changing environment. Our objectives were to compare performance on concurrent variable-interval variable-ratio schedules with extant data on concurrent variable-interval variable-interval schedules using a dynamic choice procedure and to extend earlier work on concurrent variable-interval variable-ratio schedules. We analyzed performances at different time scales, finding strong similarities between concurrent variable-interval variable-interval and concurrent variable-interval variable- ratio performance within dynamic choice procedures. Time-based measures revealed almost identical performance in the two procedures compared with response-based measures, supporting the view that choice is best understood as time allocation. Performance at the smaller time scale of visits accorded with the tendency seen in earlier research toward developing a pattern of strong preference for and long visits to the richer alternative paired with brief "samples" at the leaner alternative ("fix and sample"). © 2017 Society for the Experimental Analysis of Behavior.

Investigation of load reduction for a variable speed, variable pitch, and variable coning wind turbine

Energy Technology Data Exchange (ETDEWEB)

Pierce, K. [Univ. of Utah, Salt Lake City, UT (United States)

1997-12-31

A two bladed, variable speed and variable pitch wind turbine was modeled using ADAMS{reg_sign} to evaluate load reduction abilities of a variable coning configuration as compared to a teetered rotor, and also to evaluate control methods. The basic dynamic behavior of the variable coning turbine was investigated and compared to the teetered rotor under constant wind conditions as well as turbulent wind conditions. Results indicate the variable coning rotor has larger flap oscillation amplitudes and much lower root flap bending moments than the teetered rotor. Three methods of control were evaluated for turbulent wind simulations. These were a standard IPD control method, a generalized predictive control method, and a bias estimate control method. Each control method was evaluated for both the variable coning configuration and the teetered configuration. The ability of the different control methods to maintain the rotor speed near the desired set point is evaluated from the RMS error of rotor speed. The activity of the control system is evaluated from cycles per second of the blade pitch angle. All three of the methods were found to produce similar results for the variable coning rotor and the teetered rotor, as well as similar results to each other.

About hidden influence of predictor variables: Suppressor and mediator variables

Directory of Open Access Journals (Sweden)

Milovanović Boško

2013-01-01

Full Text Available In this paper procedure for researching hidden influence of predictor variables in regression models and depicting suppressor variables and mediator variables is shown. It is also shown that detection of suppressor variables and mediator variables could provide refined information about the research problem. As an example for applying this procedure, relation between Atlantic atmospheric centers and air temperature and precipitation amount in Serbia is chosen. [Projekat Ministarstva nauke Republike Srbije, br. 47007

Close Binaries in the 21st Century: New Opportunities and Challenges

CERN Document Server

Giménez, Àlvaro; Niarchos, Panagiotis; Rucinski, Slavek

2006-01-01

An International Conference entitled "Close Binaries in the 21st Century: New Opportunities and Challenges", was held in Syros island, Greece, from 27 to 30 June, 2005. There are many binary star systems whose components are so close together, that they interact in various ways. Stars in such systems do not pass through all stages of their evolution independently of each other; in fact their evolutionary path is significantly affected by their companions. Processes of interaction include gravitational effects, mutual irradiation, mass exchange, mass loss from the system, phenomena of extended atmospheres, semi-transparent atmospheric clouds, variable thickness disks and gas streams. The zoo of Close Binary Systems includes: Close Eclipsing Binaries (Detached, Semi-detached, Contact), High and Low-Mass X-ray Binaries, Cataclysmic Variables, RS CVn systems, Pulsar Binaries and Symbiotic Stars. The study of these binaries triggered the development of new branches of astrophysics dealing with the structure and ev...

Variable importance in latent variable regression models

NARCIS (Netherlands)

Kvalheim, O.M.; Arneberg, R.; Bleie, O.; Rajalahti, T.; Smilde, A.K.; Westerhuis, J.A.

2014-01-01

The quality and practical usefulness of a regression model are a function of both interpretability and prediction performance. This work presents some new graphical tools for improved interpretation of latent variable regression models that can also assist in improved algorithms for variable

Using variable combination population analysis for variable selection in multivariate calibration.

Science.gov (United States)

Yun, Yong-Huan; Wang, Wei-Ting; Deng, Bai-Chuan; Lai, Guang-Bi; Liu, Xin-bo; Ren, Da-Bing; Liang, Yi-Zeng; Fan, Wei; Xu, Qing-Song

2015-03-03

Variable (wavelength or feature) selection techniques have become a critical step for the analysis of datasets with high number of variables and relatively few samples. In this study, a novel variable selection strategy, variable combination population analysis (VCPA), was proposed. This strategy consists of two crucial procedures. First, the exponentially decreasing function (EDF), which is the simple and effective principle of 'survival of the fittest' from Darwin's natural evolution theory, is employed to determine the number of variables to keep and continuously shrink the variable space. Second, in each EDF run, binary matrix sampling (BMS) strategy that gives each variable the same chance to be selected and generates different variable combinations, is used to produce a population of subsets to construct a population of sub-models. Then, model population analysis (MPA) is employed to find the variable subsets with the lower root mean squares error of cross validation (RMSECV). The frequency of each variable appearing in the best 10% sub-models is computed. The higher the frequency is, the more important the variable is. The performance of the proposed procedure was investigated using three real NIR datasets. The results indicate that VCPA is a good variable selection strategy when compared with four high performing variable selection methods: genetic algorithm-partial least squares (GA-PLS), Monte Carlo uninformative variable elimination by PLS (MC-UVE-PLS), competitive adaptive reweighted sampling (CARS) and iteratively retains informative variables (IRIV). The MATLAB source code of VCPA is available for academic research on the website: http://www.mathworks.com/matlabcentral/fileexchange/authors/498750. Copyright © 2015 Elsevier B.V. All rights reserved.

76 FR 10587 - Product Cancellation Order for Certain Pesticide Registrations

Science.gov (United States)

2011-02-25

...-00160 Unicorn House and Phenothrin Carpet Spray 11. Tetramethrin 028293-00215 Unicorn IGR Phenothrin... company number. This number corresponds to the first part of the EPA registration numbers of the products listed in this unit. Table 4 --Registrants of Cancelled Products Company No. Company name and address 192...

Susceptibility of Tribolium castaneum and Trogoderma variabile larvae and adults exposed to methoprene-treated woven packaing material

Science.gov (United States)

Methoprene is an insect growth regulator (IGR) registered in the United States for direct application to stored raw grains, as an aerosol or residual contact insecticide, or for use as a packaging treatment for protection of bagged processed food products. A series of tests were conducted to determi...

Optical spectrophotometry of oscillations and flickering in AE Aquarii

Science.gov (United States)

Welsh, William F.; Horne, Keith; Oke, J. B.

1993-01-01

We observed rapid variations in the nova-like cataclysmic variable AE Aquarii for 1.7 hr with 4.3 s time resolution using the 30-channel (3227-10494 A) spectrophotometer on the Hale 5 m telescope. The 16.5 and 33.0 s oscillations show a featureless blue spectrum that can be represented by a blackbody with temperature and area much smaller than the accretion disk. Models consisting of the sum of a K star spectrum and a hydrogen slab in LTE at T = 6000-10,000 K can fit the spectrum of AE Aquarii reasonably well. The spectrum of a flare indicates optically thin gas with T = 8000-12,000 K. The energy released by the flare is large compared to typical stellar flares.

Restablished Accretion in Post-outburst Classical Novae Revealed by X-rays

Science.gov (United States)

Hernanz, Margarita; Ferri, Carlo; Sala, Glòria

2009-05-01

Classical novae are explosions on accreting white dwarfs (hereinafter WDs) in cataclysmic variables (hereinafter CVs) a hydrogen thermonuclear runaway on top of the WD is responsible for the outburst. X-rays provide a unique way to study the turn-off of H-burning, because super soft X-rays reveal the hot WD photosphere, but also to understand how accretion is established again in the binary system. Observations with XMM-Newton of some post-outburst novae have revealed such a process, but a coverage up to larger energies -as Simbol-X will provide- is fundamental to well understand the characteristics of the binary system and of the nova ejecta. We present a brief summary of our results up to now and prospects for the Simbol-X mission.

High-speed photometry of the dwarf nova Z Cha in quiescence

International Nuclear Information System (INIS)

Wood, Janet; Horne, Keith; Berriman, Graham; O'Donoghue, Darragh; Warner, Brian

1986-01-01

High-speed white light photometry of the cataclysmic variable star Z Cha is used to study the structure of the system and to derive the properties of its components. The white dwarf and bright spot eclipse timings require a mass ratio, q=Msub(R)/Msub(WD) of 0.146 0 .9>i>81 0 .6. The infalling stream passes through the light centre of the bright spot. If the central luminous object is the white dwarf its mass is 0.54+-0.01 Msolar mass which corresponds to a secondary star mass of 0.081+-0.003 Msolar mass. Agreement between colour and brightness temperatures for the white dwarf and bright spot provide a rough confirmation of the 97 pc distance. (author)

Effects of buprofezin and diflubenzuron on various developmental stages of Asian citrus psyllid, Diaphorina citri.

Science.gov (United States)

Tiwari, Siddharth; Clayson, Paul J; Kuhns, Emily H; Stelinski, Lukasz L

2012-10-01

Diaphorina citri populations in Florida are developing resistance to commonly used neurotoxic insecticides. Alternatives to neurotoxins, such as insect growth regulators, are needed to control this season-long subtropical pest to prevent or delay development of insecticide resistance. In the present investigation, two insect growth regulators (IGRs), buprofezin and diflubenzuron, were evaluated against various developmental stages of D. citri. The 0-1-day-old D. citri eggs were more susceptible to buprofezin and diflubenzuron than the 3-4-day-old eggs. Adult emergence was completely suppressed by treating first- or third-instar nymphs with buprofezin or diflubenzuron at 30-240 or 23-184 µg mL(-1) rates respectively. Treatment of fifth-instar nymphs with diflubenzuron at a rate of 184 µg mL(-1) and with buprofezin at 30-240 µg mL(-1) rates resulted in approximately 20 and 15-80% reductions in adult emergence respectively. The mean number of eggs per plant was reduced at 5 days after topical treatment with diflubenzuron. Mean egg hatch per plant was reduced at 5 and 6-15 days after topical treatments with buprofezin and diflubenzuron respectively. Buprofezin and diflubenzuron effectively suppressed D. citri adult emergence. D. citri were more susceptible as early (first-third-instar) than late (fifth-instar) nymphs. Both IGRs inhibited egg production and egg hatch. Reduction in the number of subsequent offspring suggests reduced vertical transmission of Candidatus Liberibacter asiaticus, the pathogen thought to cause citrus greening disease. The present results indicate that both IGRs tested here should be effective tools for rotation in insecticide-based D. citri management programs. Copyright © 2012 Society of Chemical Industry.

Toxicity of seven foliar insecticides to four insect parasitoids attacking citrus and cotton pests.

Science.gov (United States)

Prabhaker, Nilima; Morse, J G; Castle, S J; Naranjo, S E; Henneberry, T J; Toscano, N C

2007-08-01

Laboratory studies were carried out to compare the toxicity of seven foliar insecticides to four species of adult beneficial insects representing two families of Hymenoptera: Aphelinidae (Aphytis melinus Debach, Eretmocerus eremicus Rose & Zolnerowich, and Encarsiaformosa Gahan) and Mymaridae (Gonatocerus ashmeadi Girault) that attack California red scale, Aonidiella aurantii (Maskell); sweetpotato whitefly, Bemisia tabaci (Gennadius) (both E. eremicus and E. formosa); and glassy-winged sharpshooter, Homalodisca vitripennis (Germar), respectively. Insecticides from four pesticide classes were evaluated using a petri dish bioassay technique across a range of concentrations to develop dosage-mortality regressions. Insecticides tested included acetamiprid (neonicotinoid); chlorpyrifos (organophosphate); bifenthrin, cyfluthrin, and fenpropathrin (pyrethroids); and buprofezin and pyriproxyfen (insect growth regulators [IGRs]). Chlorpyrifos was consistently the most toxic pesticide to all four species of beneficial insects tested based on LC50 values recorded 24 h posttreatment compared with 48-h LC50 values with the neonicotinoid and pyrethroids or 96 h with the IGRs. Among the three pyrethroids, fenpropathrin was usually less toxic (except similar toxicity to A. melinus) than was cyfluthrin, and it was normally less toxic (except similar toxicity with E. formosa) than was bifenthrin. Acetamiprid was generally less toxic than bifenthrin (except similar toxicity with G. ashmeadi). The IGRs buprofezin and pyriproxyfen were usually less toxic than the contact pesticides, but we did not test for possible impacts on female fecundity. For all seven pesticides tested, A. melinus was the most susceptible parasitoid of the four test species. The data presented here will provide pest managers with specific information on the compatibility of select insecticides with natural enemies attacking citrus and cotton, Gossypium hirsutum L., pests.

Financial and economic implications of solid waste management in ...

African Journals Online (AJOL)

Descriptively, a large proportion of respondents strongly agreed that solid waste management has significant effect on internally generated revenue (IGR) and youth employment in the state. Consistently, the computed Z values laid between -1.96 and 1.96 of their critical values implying the acceptance of the two alternative ...

Pulsating variables

International Nuclear Information System (INIS)

1989-01-01

The study of stellar pulsations is a major route to the understanding of stellar structure and evolution. At the South African Astronomical Observatory (SAAO) the following stellar pulsation studies were undertaken: rapidly oscillating Ap stars; solar-like oscillations in stars; 8-Scuti type variability in a classical Am star; Beta Cephei variables; a pulsating white dwarf and its companion; RR Lyrae variables and galactic Cepheids. 4 figs

Variable mechanical ventilation.

Science.gov (United States)

Fontela, Paula Caitano; Prestes, Renata Bernardy; Forgiarini, Luiz Alberto; Friedman, Gilberto

2017-01-01

To review the literature on the use of variable mechanical ventilation and the main outcomes of this technique. Search, selection, and analysis of all original articles on variable ventilation, without restriction on the period of publication and language, available in the electronic databases LILACS, MEDLINE®, and PubMed, by searching the terms "variable ventilation" OR "noisy ventilation" OR "biologically variable ventilation". A total of 36 studies were selected. Of these, 24 were original studies, including 21 experimental studies and three clinical studies. Several experimental studies reported the beneficial effects of distinct variable ventilation strategies on lung function using different models of lung injury and healthy lungs. Variable ventilation seems to be a viable strategy for improving gas exchange and respiratory mechanics and preventing lung injury associated with mechanical ventilation. However, further clinical studies are necessary to assess the potential of variable ventilation strategies for the clinical improvement of patients undergoing mechanical ventilation.

Low-frequency quasi-periodic oscillation from the 11 Hz accreting pulsar in Terzan 5: not frame dragging

NARCIS (Netherlands)

Altamirano, D.; Ingram, A.; van der Klis, M.; Wijnands, R.; Linares, M.; Homan, J.

2012-01-01

We report on six RXTE observations taken during the 2010 outburst of the 11 Hz accreting pulsar IGR J17480-2446 located in the globular cluster Terzan 5. During these observations we find power spectra which resemble those seen in Z-type high-luminosity neutron star low-mass X-ray binaries, with a

Residents' Perceptions of Property Rating in a Traditional African City

African Journals Online (AJOL)

2015-04-22

Apr 22, 2015 ... Council for the Development of Social Science Research in Africa, 2014. (ISSN 0850-3907) ... The IGR includes the local tax, property tax and fees and charges. Of importance ... the world. .... Each of the above is referred to as the suburban, intermediate or ... for making and levying rates to rating authorities.

Trauma Informed Guilt Reduction (TrIGR) Intervention

Science.gov (United States)

2017-10-01

maintenance of posttraumatic distress and a range of adverse outcomes, including posttraumatic stress disorder (PTSD), depression and suicidality , and...outcomes, including posttraumatic stress disorder (PTSD), depression and suicidality , and alcohol/substance use disorders. There is a pressing need...deployment, posttraumatic, distress, PTSD, depression , functioning, psychotherapy, intervention 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT

VariableR Reclustering in Multiple Top Quark and W Boson Events

Energy Technology Data Exchange (ETDEWEB)

Hyde, Jeremy [SLAC National Accelerator Lab., Menlo Park, CA (United States)

2015-08-14

VariableR jet reclustering is an innovative technique that allows for the reconstruction of boosted object over a wide range of kinematic regimes. Such capability enables the efficient identification of events with multiple boosted top quarks which is a typical signature for new physics processes such as the production of the supersymmetric partner of the gluon. In order to evaluate the performance of the algorithm, the VariableR reclustered jets are compared with fixed radius reclustered jets. The flexibility of the algorithm is tested by reconstructing both boosted top quarks and boosted W bosons. The VariableR reclustering method is found to be more efficient than the fixed radius algorithm at identifying top quarks and W bosons in events with four top quarks, therefore enhancing the sensitivity for gluino searches.

Low-Frequency Temporal Variability in Mira and Semiregular Variables

Science.gov (United States)

Templeton, Matthew R.; Karovska, M.; Waagen, E. O.

2012-01-01

We investigate low-frequency variability in a large sample of Mira and semiregular variables with long-term visual light curves from the AAVSO International Database. Our aim is to determine whether we can detect and measure long-timescale variable phenomena in these stars, for example photometric variations that might be associated with supergranular convection. We analyzed the long-term light curves of 522 variable stars of the Mira and SRa, b, c, and d classes. We calculated their low-frequency time-series spectra to characterize rednoise with the power density spectrum index, and then correlate this index with other observable characteristics such as spectral type and primary pulsation period. In our initial analysis of the sample, we see that the semiregular variables have a much broader range of spectral index than the Mira types, with the SRb subtype having the broadest range. Among Mira variables we see that the M- and S-type Miras have similarly wide ranges of index, while the C-types have the narrowest with generally shallower slopes. There is also a trend of steeper slope with larger amplitude, but at a given amplitude, a wide range of slopes are seen. The ultimate goal of the project is to identify stars with strong intrinsic red noise components as possible targets for resolved surface imaging with interferometry.

Combined effects of 19 common variations on type 2 diabetes in Chinese: results from two community-based studies.

Directory of Open Access Journals (Sweden)

Min Xu

2010-11-01

Full Text Available Many susceptible loci for type 2 diabetes mellitus (T2DM have recently been identified from Caucasians through genome wide association studies (GWAS. We aimed to determine the association of 11 known loci with T2DM and impaired glucose regulation (IGR, individually and in combination, in Chinese.Subjects were enrolled in: (1 a case-control study including 1825 subjects with T2DM, 1487 with IGR and 2200 with normal glucose regulation; and (2 a prospective cohort with 734 non-diabetic subjects at baseline. The latter was followed up for 3.5 years, in which 67 subjects developed T2DM. Nineteen single nucleotide polymorphisms (SNPs were selected to replicate in both studies. We found that CDKAL1 (rs7756992, SLC30A8 (rs13266634, rs2466293, CDKN2A/2B (rs10811661 and KCNQ1 (rs2237892 were associated with T2DM with odds ratio from 1.21 to 1.35. In the prospective study, the fourth quartile of risk scores based on the combined effects of the risk alleles had 3.05 folds (95% CI, 1.31-7.12 higher risk for incident T2DM as compared with the first quartile, after adjustment for age, gender, body mass index and diabetes family history. This combined effect was confirmed in the case-control study after the same adjustments. The addition of the risk scores to the model of clinical risk factors modestly improved discrimination for T2DM by 1.6% in the case-control study and 2.9% in the prospective study.Our study provided further evidence for these GWAS derived SNPs as the genetic susceptible loci for T2DM in Chinese and extended this association to IGR.

Overexpression of an Outer Membrane Protein Associated with Decreased Susceptibility to Carbapenems in Proteus mirabilis

Science.gov (United States)

Tsai, Yi-Lin; Wang, Min-Cheng; Hsueh, Po-Ren; Liu, Ming-Che; Hu, Rouh-Mei; Wu, Yue-Jin; Liaw, Shwu-Jen

2015-01-01

Proteus mirabilis isolates commonly have decreased susceptibility to imipenem. Previously, we found P. mirabilis hfq mutant was more resistant to imipenem and an outer membrane protein (OMP) could be involved. Therefore, we investigated the role of this OMP in carbapenem susceptibility. By SDS-PAGE we found this OMP (named ImpR) was increased in hfq mutant and LC-MS/MS revealed it to be the homologue of Salmonella YbfM, which is a porin for chitobiose and subject to MicM (a small RNA) regulation. We demonstrated that ImpR overexpression resulted in increased carbapenem MICs in the laboratory strain and clinical isolates. Chitobiose induced expression of chb (a chitobiose utilization operon). Real-time RT-PCR and SDS-PAGE were performed to elucidate the relationship of hfq, impR, chb and MicM in P. mirabilis. We found MicM RNA was decreased in hfq mutant and chbBC-intergenic region (chbBC-IGR) overexpression strain (chbIGRov), while impR mRNA was increased in hfq mutant, micM mutant and chbIGRov strain. In addition, mutation of hfq or micM and overexpression of chbBC-IGR increased ImpR protein level. Accordingly, chitobiose made wild-type have higher levels of ImpR protein and are more resistant to carbapenems. Hfq- and MicM-complemented strains restored wild-type MICs. Mutation of both impR and hfq eliminated the increase in carbapenem MICs observed in hfq mutant and ImpR-complementation of hfq/impR double mutant resulted in MICs as hfq mutant, indicating that the ImpR-dependent decreased carbapenem susceptibility of hfq mutant. These indicate MicM was antisense to impR mRNA and was negatively-regulated by chbBC-IGR. Together, overexpression of ImpR contributed to the decreased carbapenem susceptibility in P. mirabilis. PMID:25756370

Dosimetric consequences of translational and rotational errors in frame-less image-guided radiosurgery

Directory of Open Access Journals (Sweden)

Guckenberger Matthias

2012-04-01

Full Text Available Abstract Background To investigate geometric and dosimetric accuracy of frame-less image-guided radiosurgery (IG-RS for brain metastases. Methods and materials Single fraction IG-RS was practiced in 72 patients with 98 brain metastases. Patient positioning and immobilization used either double- (n = 71 or single-layer (n = 27 thermoplastic masks. Pre-treatment set-up errors (n = 98 were evaluated with cone-beam CT (CBCT based image-guidance (IG and were corrected in six degrees of freedom without an action level. CBCT imaging after treatment measured intra-fractional errors (n = 64. Pre- and post-treatment errors were simulated in the treatment planning system and target coverage and dose conformity were evaluated. Three scenarios of 0 mm, 1 mm and 2 mm GTV-to-PTV (gross tumor volume, planning target volume safety margins (SM were simulated. Results Errors prior to IG were 3.9 mm ± 1.7 mm (3D vector and the maximum rotational error was 1.7° ± 0.8° on average. The post-treatment 3D error was 0.9 mm ± 0.6 mm. No differences between double- and single-layer masks were observed. Intra-fractional errors were significantly correlated with the total treatment time with 0.7mm±0.5mm and 1.2mm±0.7mm for treatment times ≤23 minutes and >23 minutes (p5% in 14% of the patients. A 1 mm safety margin fully compensated intra-fractional patient motion. Conclusions IG-RS with online correction of translational errors achieves high geometric and dosimetric accuracy. Intra-fractional errors decrease target coverage and conformity unless compensated with appropriate safety margins.

NuSTAR Hard X-ray Survey of the Galactic Center Region. I. Hard X-ray Morphology and Spectroscopy of the Diffuse Emission

DEFF Research Database (Denmark)

Mori, Kaya; Hailey, Charles J.; Krivonos, Roman

2015-01-01

We present the first sub-arcminute images of the Galactic Center above 10 keV, obtained with NuSTAR. NuSTAR resolves the hard X-ray source IGR J17456-2901 into non-thermal X-ray filaments, molecular clouds, point sources, and a previously unknown central component of hard X-ray emission (CHXE). Nu...

INTEGRAL spots renewed activity from H1743-322

DEFF Research Database (Denmark)

Kuulkers, E.; Brandt, Søren Kristian; Budtz-Jørgensen, Carl

2008-01-01

INTEGRAL Galactic Bulge monitoring (see ATels #438, #874, #1005, #1385) observations on UT 2008 Sep 23 08:51-12:34 reveal a new outburst of the Galactic black-hole candidate and X-ray transient H1743-322/IGR J17464-3213 (see ATels #132, #136, #576, #593, #1348, #1385, #1414). JEM-X and IBIS...

Impact of Subsurface Temperature Variability on Meteorological Variability: An AGCM Study

Science.gov (United States)

Mahanama, S. P.; Koster, R. D.; Liu, P.

2006-05-01

Anomalous atmospheric conditions can lead to surface temperature anomalies, which in turn can lead to temperature anomalies deep in the soil. The deep soil temperature (and the associated ground heat content) has significant memory -- the dissipation of a temperature anomaly may take weeks to months -- and thus deep soil temperature may contribute to the low frequency variability of energy and water variables elsewhere in the system. The memory may even provide some skill to subseasonal and seasonal forecasts. This study uses two long-term AGCM experiments to isolate the contribution of deep soil temperature variability to variability elsewhere in the climate system. The first experiment consists of a standard ensemble of AMIP-type simulations, simulations in which the deep soil temperature variable is allowed to interact with the rest of the system. In the second experiment, the coupling of the deep soil temperature to the rest of the climate system is disabled -- at each grid cell, the local climatological seasonal cycle of deep soil temperature (as determined from the first experiment) is prescribed. By comparing the variability of various atmospheric quantities as generated in the two experiments, we isolate the contribution of interactive deep soil temperature to that variability. The results show that interactive deep soil temperature contributes significantly to surface temperature variability. Interactive deep soil temperature, however, reduces the variability of the hydrological cycle (evaporation and precipitation), largely because it allows for a negative feedback between evaporation and temperature.

Variable selection in multivariate calibration based on clustering of variable concept.

Science.gov (United States)

Farrokhnia, Maryam; Karimi, Sadegh

2016-01-01

Recently we have proposed a new variable selection algorithm, based on clustering of variable concept (CLoVA) in classification problem. With the same idea, this new concept has been applied to a regression problem and then the obtained results have been compared with conventional variable selection strategies for PLS. The basic idea behind the clustering of variable is that, the instrument channels are clustered into different clusters via clustering algorithms. Then, the spectral data of each cluster are subjected to PLS regression. Different real data sets (Cargill corn, Biscuit dough, ACE QSAR, Soy, and Tablet) have been used to evaluate the influence of the clustering of variables on the prediction performances of PLS. Almost in the all cases, the statistical parameter especially in prediction error shows the superiority of CLoVA-PLS respect to other variable selection strategies. Finally the synergy clustering of variable (sCLoVA-PLS), which is used the combination of cluster, has been proposed as an efficient and modification of CLoVA algorithm. The obtained statistical parameter indicates that variable clustering can split useful part from redundant ones, and then based on informative cluster; stable model can be reached. Copyright © 2015 Elsevier B.V. All rights reserved.

A Combined Raman Spectroscopic and Thermogravimetric Analysis Study on Oxidation of Coal with Different Ranks

Directory of Open Access Journals (Sweden)

Weiqing Zhang

2015-01-01

Full Text Available Raman spectroscopy and nonisothermal thermogravimetric analysis (TGA measurements have been reported for different rank coals (lignite, bituminous coal, and anthracite and the relationship between the measurements was examined. It was found that the Raman spectra parameters can be used to characterize structure changes in the different rank coals, such as the band area ratios based on the curve-fitted results. Higher ranked coal was found to have higher values of IGR/IAll and IG+GR/IAll but lower values of ID/I(G+GR, IDL/I(G+GR, IS+SL/I(G+GR, and I(GL+GL'/I(G+GR. The oxidation properties of the coal samples were characterized by the reactivity indexes Tig, T20%, and Tmax from TGA data which were found to correlate well with the band area ratios of IGR/IAll, IG+GR/IAll, and IS+SL/I(G+GR. Based on these correlations, the Raman band area ratios were found to correlate with the oxidation activity of coal providing additional structural information which can be used to understand the changes in the TGA measurements.

New developments in insecticide resistance in the glasshouse whitefly (Trialeurodes vaporariorum) and the two-spotted spider mite (Tetranychus urticae) in the UK.

Science.gov (United States)

Gorman, Kevin; Hewitt, Fiona; Denholm, Ian; Devine, Gregor J

2002-02-01

A recent survey of insecticide resistance in two of the most problematic pests in UK glasshouses revealed some new developments. At least some individuals in all UK samples of Trialeurodes vaporariorum that were tested resisted the insect growth regulator (IGR) buprofezin. The most strongly resistant strains were unaffected by the field application rate of this compound, and even samples from populations that had never been exposed to buprofezin contained individuals that survived the highest concentration applied (10,000 mg litre-1). The field rate of buprofezin was shown to select for resistance through vapour action alone. The benzophenylurea teflubenzuron, an unrelated IGR, was cross-resisted by buprofezin-resistant individuals. There was no evidence of resistance to imidacloprid, but all T vaporariorum strains tested, regardless of origin, exhibited a high innate tolerance to nicotine, when compared with another whitefly species, Bemisia tabaci. Marked resistance to fenbutatin oxide and tebufenpyrad was found in single glasshouse populations of Tetranychus urticae, but these compounds and abamectin appeared to remain highly effective against all other strains collected.

Pest insect olfaction in an insecticide-contaminated environment: info-disruption or hormesis effect.

Science.gov (United States)

Tricoire-Leignel, Hélène; Thany, Steeve Hervé; Gadenne, Christophe; Anton, Sylvia

2012-01-01

Most animals, including pest insects, live in an "odor world" and depend strongly on chemical stimuli to get information on their biotic and abiotic environment. Although integrated pest management strategies including the use of insect growth regulators (IGRs) are increasingly developed, most insect pest treatments rely on neurotoxic chemicals. These molecules are known to disrupt synaptic transmission, affecting therefore sensory systems. The wide-spread use of neurotoxic insecticides and the growing use of IGRs result in residual accumulation of low concentrations in the environment. These insecticide residues could act as an "info-disruptor" by modifying the chemical communication system, and therefore decrease chances of reproduction in target insects. However, residues can also induce a non-expected hormesis effect by enhancing reproduction abilities. Low insecticide doses might thus induce adaptive processes in the olfactory pathway of target insects, favoring the development of resistance. The effect of sublethal doses of insecticides has mainly been studied in beneficial insects such as honeybees. We review here what is known on the effects of sublethal doses of insecticides on the olfactory system of insect pests.

Synthesis and Larvicidal Activity of Novel Thenoylhydrazide Derivatives

Science.gov (United States)

Song, Gao-Peng; Hu, De-Kun; Tian, Hao; Li, Ya-Sheng; Cao, Yun-Shen; Jin, Hong-Wei; Cui, Zi-Ning

2016-03-01

A pair of chemical isomeric structures of novel N-tert-butylphenyl thenoylhydrazide compounds I and II were designed and synthesized. Their structures were characterized by MS, IR, 1H NMR, elemental analysis and X-ray single crystal diffraction. The regioselectivity of the Meerwein arylation reaction and the electrophilic substitution reaction of N-tert-butyl hydrazine were studied by density functional theory (DFT) quantum chemical method. The larvicidal tests revealed that some compounds I had excellent larvicidal activity against Culex pipiens pallens. As the candidates of insect growth regulators (IGRs), the larval growth inhibition and regulation against Culex pipiens pallens were examined for some compounds, especially I1 and I7. Compounds I1 and I7 were further indicated as an ecdysteroid agonist by reporter gene assay on the Spodoptera frugiperda cell line (Sf9 cells). Finally, a molecular docking study of compound I7 was conducted, which was not only beneficial to understand the structure-activity relationship, but also useful for development of new IGRs for the control of mosquitos.

Resistance Status to the Insecticides Temephos, Deltamethrin, and Diflubenzuron in Brazilian Aedes aegypti Populations

Science.gov (United States)

Viana-Medeiros, Priscila Fernandes; Araújo, Simone Costa; Martins, Ademir J.; Lima, José Bento Pereira

2016-01-01

Insecticides are still largely applied in public health to control disease vectors. In Brazil, organophosphates (OP) and pyrethroids (PY) are used against Aedes aegypti for years. Since 2009 Insect Growth Regulators (IGR) are also employed in the control of larvae. We quantified resistance to temephos (OP), deltamethrin (PY), and diflubenzuron (IGR) of A. aegypti samples from 12 municipalities distributed throughout the country, collected between 2010 and 2012. High levels of resistance to neurotoxic insecticides were detected in almost all populations: RR95 to temephos varied between 4.0 and 27.1; the lowest RR95 to deltamethrin was 13.1, and values higher than 70.0 were found. In contrast, all samples were susceptible to diflubenzuron (RR95 < 2.3). Biochemical tests performed with larvae and adults discarded the participation of acetylcholinesterase, the OP target, and confirmed involvement of the detoxifying enzymes esterases, mixed function oxidases, and glutathione-S-transferases. The results obtained were discussed taking into account the public chemical control component and the increase in the domestic use of insecticides during dengue epidemic seasons in the evaluated municipalities. PMID:27419140

Pest insect olfaction in an insecticide-contaminated environment : info-disruption or hormesis effect

Directory of Open Access Journals (Sweden)

Hélène eTricoire-Leignel

2012-03-01

Full Text Available Most animals, including pest insects, live in an odour world and depend strongly on chemical stimuli to get information on their biotic and abiotic environment. Although integrated pest management strategies including the use of insect growth regulators (IGRs are increasingly developed, most insect pest treatments rely on neurotoxic chemicals. These molecules are known to disrupt synaptic transmission, affecting therefore sensory systems. The wide-spread use of neurotoxic insecticides and the growing use of IGRs result in residual accumulation of low concentrations in the environment. These insecticide residues could act as an info-disruptor by modifying the chemical communication system, and therefore decrease chances of reproduction in target insects. However, residues can also induce a non-expected hormesis effect by enhancing reproduction abilities. Low insecticide doses might thus induce adaptive processes in the olfactory pathway of target insects, favouring the development of resistance. The effect of sublethal doses of insecticides has mainly been studied in beneficial insects such as honeybees. We review here what is known on the effects of sublethal doses of insecticides on the olfactory system of insect pests.

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

U-Pb geochronology of zircons form lunar Breccia 73217 using a sensitive high mass-resolution ion microprobe

International Nuclear Information System (INIS)

Compston, W.; Williams, I.S.

1984-01-01

U-Pb age determinations on four lunar zircons from existing thin-sections of one highland breccia, 73217, using the recently constructed ion microprobe SHRIMP, are reported. The analytical reproducibility of SHRIMP is demonstrated, and procedures for measuring Pb/U, Th/U, and corecting for initial Pb are explained. Electron microprobe analyses for the zircons are also reported. The results show that the four zircons survived the lunar cataclysm without any identifiable effects on their U-Pb systematics. All four indicate a single age of 4356 +23 or -14 m.y. The zircons have experienced small variable amounts of Pb loss since crystallization, from almost zero up to about 10 percent. If this occurred during one later event, then age of the latter is between 1100 and 2300 m.y. 18 references

Implications of global warming on human health

International Nuclear Information System (INIS)

Singh, R.K.; Syam, P.V.S.

1997-01-01

Due to the build up of green house gases in atmosphere, less heat escapes through the atmosphere promoting global warming. This may result in world wide droughts, sea-level rise inundating islands and coastal countries, cataclysmic hurricanes etc. Human health as a result of these changes, will be affected both physiologically and psychologically. Physiological effects may be more pronounced in cases occurring due to changes in rainfall and temperature patterns, food production amounts, water availability, etc. Psychological impact may be more in cases of catastrophes like floods, hurricanes or famine. In this paper, an attempt has been made to highlight the implications of global warming on human health due to temperature change. Food production changes and ultra-violet radiation effects and cataclysmic disaster effects. (author)

The nebular variables

CERN Document Server

Glasby, John S

1974-01-01

The Nebular Variables focuses on the nebular variables and their characteristics. Discussions are organized by type of nebular variable, namely, RW Aurigae stars, T Orionis stars, T Tauri stars, and peculiar nebular objects. Topics range from light variations of the stars to their spectroscopic and physical characteristics, spatial distribution, interaction with nebulosity, and evolutionary features. This volume is divided into four sections and consists of 25 chapters, the first of which provides general information on nebular variables, including their stellar associations and their classifi

HOW NORMAL IS VARIABLE, OR HOW VARIABLE IS NORMAL

NARCIS (Netherlands)

TOUWEN, BCL

Variability is an important property of the central nervous system, and it shows characteristic changes during infancy and childhood. The large amount of variations in the performance of sensomotor functions in infancy is called indiscriminate or primary variability. During toddling age the child

Response-rate differences in variable-interval and variable-ratio schedules: An old problem revisited

OpenAIRE

Cole, Mark R.

1994-01-01

In Experiment 1, a variable-ratio 10 schedule became, successively, a variable-interval schedule with only the minimum interreinforcement intervals yoked to the variable ratio, or a variable-interval schedule with both interreinforcement intervals and reinforced interresponse times yoked to the variable ratio. Response rates in the variable-interval schedule with both interreinforcement interval and reinforced interresponse time yoking fell between the higher rates maintained by the variable-...

Quasi-periodic oscillations from post-shock accretion column of polars

Science.gov (United States)

Bera, Prasanta; Bhattacharya, Dipankar

2018-02-01

A set of strongly magnetized accreting white dwarfs (polars) shows quasi-periodic oscillations (QPOs) with frequency about a Hz in their optical luminosity. These Hz-frequency QPOs are thought to be generated by intensity variations of the emitted radiation originating at the post-shock accretion column. Thermal instability in the post-shock region, triggered by efficient cooling process at the base, is believed to be the primary reason behind the temporal variability. Here, we study the structure and the dynamical properties of the post-shock accretion column including the effects of bremsstrahlung and cyclotron radiation. We find that the presence of significant cyclotron emission in optical band reduces the overall variability of the post-shock region. In the case of a larger post-shock region above the stellar surface, the effects of stratification due to stellar gravity become important. An accretion column, influenced by the strong gravity, has a smaller variability as the strength of the thermal instability at the base of the column is reduced. On the other hand, the cool, dense plasma, accumulated just above the stellar surface, may enhance the post-shock variability due to the propagation of magnetic perturbations. These characteristics of the post-shock region are consistent with the observed properties of V834 Cen and in general with cataclysmic variable sources that exhibit QPO frequency of about a Hz.

Cognitive Variability

Science.gov (United States)

Siegler, Robert S.

2007-01-01

Children's thinking is highly variable at every level of analysis, from neural and associative levels to the level of strategies, theories, and other aspects of high-level cognition. This variability exists within people as well as between them; individual children often rely on different strategies or representations on closely related problems…

An Estimation of the Likelihood of Significant Eruptions During 2000-2009 Using Poisson Statistics on Two-Point Moving Averages of the Volcanic Time Series

Science.gov (United States)

Wilson, Robert M.

2001-01-01

Since 1750, the number of cataclysmic volcanic eruptions (volcanic explosivity index (VEI)>=4) per decade spans 2-11, with 96 percent located in the tropics and extra-tropical Northern Hemisphere. A two-point moving average of the volcanic time series has higher values since the 1860's than before, being 8.00 in the 1910's (the highest value) and 6.50 in the 1980's, the highest since the 1910's peak. Because of the usual behavior of the first difference of the two-point moving averages, one infers that its value for the 1990's will measure approximately 6.50 +/- 1, implying that approximately 7 +/- 4 cataclysmic volcanic eruptions should be expected during the present decade (2000-2009). Because cataclysmic volcanic eruptions (especially those having VEI>=5) nearly always have been associated with short-term episodes of global cooling, the occurrence of even one might confuse our ability to assess the effects of global warming. Poisson probability distributions reveal that the probability of one or more events with a VEI>=4 within the next ten years is >99 percent. It is approximately 49 percent for an event with a VEI>=5, and 18 percent for an event with a VEI>=6. Hence, the likelihood that a climatically significant volcanic eruption will occur within the next ten years appears reasonably high.

Theoretical size distribution of fossil taxa: analysis of a null model

Directory of Open Access Journals (Sweden)

Hughes Barry D

2007-03-01

Full Text Available Abstract Background This article deals with the theoretical size distribution (of number of sub-taxa of a fossil taxon arising from a simple null model of macroevolution. Model New species arise through speciations occurring independently and at random at a fixed probability rate, while extinctions either occur independently and at random (background extinctions or cataclysmically. In addition new genera are assumed to arise through speciations of a very radical nature, again assumed to occur independently and at random at a fixed probability rate. Conclusion The size distributions of the pioneering genus (following a cataclysm and of derived genera are determined. Also the distribution of the number of genera is considered along with a comparison of the probability of a monospecific genus with that of a monogeneric family.

An Unusual Transient in the Extremely Metal-Poor Galaxy SDSS J094332.35+332657.6 (Leoncino Dwarf)

Science.gov (United States)

Filho, Mercedes E.; Sánchez Almeida, J.

2018-05-01

We have serendipitously discovered that Leoncino Dwarf, an ultra-faint, low-metallicity record-holder dwarf galaxy, may have hosted a transient source, and possibly exhibited a change in morphology, a shift in the center of brightness, and peak variability of the main (host) source in images taken approximately 40 yr apart; it is highly likely that these phenomena are related. Scenarios involving a Solar System object, a stellar cluster, dust enshrouding, and accretion variability have been considered, and discarded, as the origin of the transient. Although a combination of time-varying strong and weak lensing effects, induced by an intermediate mass black hole (104 - 5 × 105 M⊙) moving within the Milky Way halo (0.1 - 4 kpc), can conceivably explain all of the observed variable galaxy properties, it is statistically highly unlikely according to current theoretical predictions, and, therefore, also discarded. A cataclysmic event such as a supernova/hypernova could have occurred, as long as the event was observed towards the later/late-stage descent of the light curve, but this scenario fails to explain the absence of a post-explosion source and/or host HII region in recent optical images. An episode related to the giant eruption of a luminous blue variable star, a stellar merger or a nova, observed at, or near, peak magnitude may explain the transient source and possibly the change in morphology/center of brightness, but can not justify the main source peak variability, unless stellar variability is evoked.

Effects of short-term variability of meteorological variables on soil temperature in permafrost regions

Science.gov (United States)

Beer, Christian; Porada, Philipp; Ekici, Altug; Brakebusch, Matthias

2018-03-01

Effects of the short-term temporal variability of meteorological variables on soil temperature in northern high-latitude regions have been investigated. For this, a process-oriented land surface model has been driven using an artificially manipulated climate dataset. Short-term climate variability mainly impacts snow depth, and the thermal diffusivity of lichens and bryophytes. These impacts of climate variability on insulating surface layers together substantially alter the heat exchange between atmosphere and soil. As a result, soil temperature is 0.1 to 0.8 °C higher when climate variability is reduced. Earth system models project warming of the Arctic region but also increasing variability of meteorological variables and more often extreme meteorological events. Therefore, our results show that projected future increases in permafrost temperature and active-layer thickness in response to climate change will be lower (i) when taking into account future changes in short-term variability of meteorological variables and (ii) when representing dynamic snow and lichen and bryophyte functions in land surface models.

Worldwide Crisis Alerting Network, Phase II. Task 2. Identification of Existing Communications Systems,

Science.gov (United States)

1980-04-01

rent flable- De:)e conservarse mientras no se %igre el funcionamiento seguro del enlace VHF RTT FREDERIKSDAL- S..INDRE STROMFJORO. SANTA MARIA...Automatic Navigation and Fuel Management Computers, Weather Radar , Air Data Computer, ACARS and Voice Communications. The service most directly...this system are located at long-range radar sites. The second air/ground functional area is terminal communications; controller/pilot communications

Variability in large-scale wind power generation: Variability in large-scale wind power generation

Energy Technology Data Exchange (ETDEWEB)

Kiviluoma, Juha [VTT Technical Research Centre of Finland, Espoo Finland; Holttinen, Hannele [VTT Technical Research Centre of Finland, Espoo Finland; Weir, David [Energy Department, Norwegian Water Resources and Energy Directorate, Oslo Norway; Scharff, Richard [KTH Royal Institute of Technology, Electric Power Systems, Stockholm Sweden; Söder, Lennart [Royal Institute of Technology, Electric Power Systems, Stockholm Sweden; Menemenlis, Nickie [Institut de recherche Hydro-Québec, Montreal Canada; Cutululis, Nicolaos A. [DTU, Wind Energy, Roskilde Denmark; Danti Lopez, Irene [Electricity Research Centre, University College Dublin, Dublin Ireland; Lannoye, Eamonn [Electric Power Research Institute, Palo Alto California USA; Estanqueiro, Ana [LNEG, Laboratorio Nacional de Energia e Geologia, UESEO, Lisbon Spain; Gomez-Lazaro, Emilio [Renewable Energy Research Institute and DIEEAC/EDII-AB, Castilla-La Mancha University, Albacete Spain; Zhang, Qin [State Grid Corporation of China, Beijing China; Bai, Jianhua [State Grid Energy Research Institute Beijing, Beijing China; Wan, Yih-Huei [National Renewable Energy Laboratory, Transmission and Grid Integration Group, Golden Colorado USA; Milligan, Michael [National Renewable Energy Laboratory, Transmission and Grid Integration Group, Golden Colorado USA

2015-10-25

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 load events. The comparison shows regions with low variability (Sweden, Spain and Germany), medium variability (Portugal, Ireland, Finland and Denmark) and regions with higher variability (Quebec, Bonneville Power Administration and Electric Reliability Council of Texas in North America; Gansu, Jilin and Liaoning in China; and Norway and offshore wind power in Denmark). For regions with low variability, the maximum 1 h wind ramps are below 10% of nominal capacity, and for regions with high variability, they may be close to 30%. Wind power variability is mainly explained by the extent of geographical spread, but also higher capacity factor causes higher variability. It was also shown how wind power ramps are autocorrelated and dependent on the operating output level. When wind power was concentrated in smaller area, there were outliers with high changes in wind output, which were not present in large areas with well-dispersed wind power.

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.

Amplification factor variable amplifier

NARCIS (Netherlands)

Akitsugu, Oshita; Nauta, Bram

2007-01-01

PROBLEM TO BE SOLVED: To provide an amplification factor variable amplifier capable of achieving temperature compensation of an amplification factor over a wide variable amplification factor range. ; SOLUTION: A Gilbert type amplification factor variable amplifier 11 amplifies an input signal and

Helium flashes on accreting white dwarfs: consequences for type 1 supernova and nova abundances

International Nuclear Information System (INIS)

Hillebrandt, W.; Ziegert, W.; Thielemann, F.K.

1986-01-01

Helium flashes on an accreting 1 Solar mass carbon-oxygen white dwarf are investigated. It is demonstrated that the outer layers of a white dwarf growing towards the Chandrasekhar limit will be significantly enriched in elements like Mg, Al, Si and S provided the mass accretion rate is of the order of a few times 10 -8 to 10 -7 Solar mass per year. Since these stars are believed to explode as type I supernovae the abundances being ejected will depend also upon the accretion history of the white dwarfs. In addition this matter will have a rather non-solar isotopic composition. Finally, our results may help to explain abundances of heavy elements observed in certain novae if the white dwarf in those binary systems has gone through a high accretion rate phase once in the past before becoming a normal cataclysmic variable

Circular polarimetry of EXO 033319-2554.2 - A new eclipsing AM Herculis star

Science.gov (United States)

Berriman, Graham; Smith, Paul S.

1988-01-01

This Letter presents circular polarimetry that unequivocally identifies EXO 033319-2554.2 as only the third eclipsing AM Her star and brings the total number of AM Her stars now identified to 14. The orbital period is 126.4 minutes, as previously reported, and defines a new short-period edge to the period gap seen in all classes of cataclysmic variable stars. EXO 033319-2554.2 shows 2.5 mag deep eclipses of the predominantly accreting magnetic pole on the white dwarf. Before the eclipse, the pole rotates into the line of sight and shows white-light circular polarization, due to cyclotron radiation, that reaches values as high as 10 percent. There is some evidence that the second pole is emitting cyclotron radiation too. How high time resolution photometry, linear polarimetry, and spectroscopy will be of great value in understanding this system.

Detailed EXOSAT and optical observations of the intermediate polar 3A0729+103: discovery of two medium energy X-ray emission regions

International Nuclear Information System (INIS)

McHardy, I.M.; Pye, J.P.; Fairall, A.P.; Menzies, J.W.

1987-01-01

EXOSAT observations of the intermediate polar cataclysmic variable 3A0729+103 reveal a strong orbital modulation, with the 2-4KeV X-rays being significantly more modulated than the 4-6keV X-rays, indicative of photoelectric absorption. The 913 second modulation which is very prominent in the optical light curve, is weakly detected in the medium-energy X-ray light curve, confirming that it represents the white dwarf spin period. These observations are well explained by a combination of two sources of medium-energy X-ray emission. The presence of two emission regions is also clearly seen in the optical spectroscopy, particularly in the intensity of the He II4686 line which has two peaks during the orbit. The authors identify the two optical emission regions with the two X-ray emission regions. (author)

XMM-Newton Proposal 03039101

Science.gov (United States)

Hernanz, Margarita

2004-10-01

Two recent galactic novae, V2487 Oph 1998 and V4633 Sgr 1998, have been detec- ted in both soft and hard X-rays with XMM. V2487 Oph showed an iron fluores- cent line only 2.7 yrs after its explosion, a clear signature of the very fast recovery of accretion, and V4633 Sgr displayed hard X-ray emission not clearly attributable to shocked ejecta or accretion. Longer observations are needed to do accurate timing and high resolution spectroscopy, essential to determine the main properties of the underlying cataclysmic variable in V2487 Oph (first nova seen in X-rays prior and after exploding) and to disentangle the origin of the hard X-rays from V4633 Sgr, through an analysis of the chemical compo- sition of the emitting thermal plasma, solar if accretion, non solar if ejecta.

Big Bang Tumor Growth and Clonal Evolution.

Science.gov (United States)

Sun, Ruping; Hu, Zheng; Curtis, Christina

2018-05-01

The advent and application of next-generation sequencing (NGS) technologies to tumor genomes has reinvigorated efforts to understand clonal evolution. Although tumor progression has traditionally been viewed as a gradual stepwise process, recent studies suggest that evolutionary rates in tumors can be variable with periods of punctuated mutational bursts and relative stasis. For example, Big Bang dynamics have been reported, wherein after transformation, growth occurs in the absence of stringent selection, consistent with effectively neutral evolution. Although first noted in colorectal tumors, effective neutrality may be relatively common. Additionally, punctuated evolution resulting from mutational bursts and cataclysmic genomic alterations have been described. In this review, we contrast these findings with the conventional gradualist view of clonal evolution and describe potential clinical and therapeutic implications of different evolutionary modes and tempos. Copyright © 2018 Cold Spring Harbor Laboratory Press; all rights reserved.

The evolution of low-mass close binary systems. IV. 0.80 M/sub sun/+0.40 M/sub sun/: Catastrophic mass loss

International Nuclear Information System (INIS)

Webbink, R.F.

1977-01-01

The evolution of both components of a 0.80 M/sub sun/+0.40 M/sub sun/ binary with initial separation 1.60 R/sub sun/ is presented. This system reaches mass transfer during core hydrogen burning in the primary. The primary has such a deep convective envelope that mass transfer proceeds on a dynamical time scale. Mass exchange is followed through the first 6.25 x 10 -3 M/sub sun/, by which time the transfer rate has reached 8.33 x 10 -4 M/sub sun/ yr -1 .It is shown that mass transfer on a dynamical time scale leads to supercritical accretion by the secondary component, and hence is presumably accompanied by extensive mass and angular momentum losses. Stability against such rapid mass transfer may impose severe limitations on the masses and mass ratios of cataclysmic variables

Allen's astrophysical quantities

CERN Document Server

2000-01-01

This new, fourth, edition of Allen's classic Astrophysical Quantities belongs on every astronomer's bookshelf. It has been thoroughly revised and brought up to date by a team of more than ninety internationally renowned astronomers and astrophysicists. While it follows the basic format of the original, this indispensable reference has grown to more than twice the size of the earlier editions to accommodate the great strides made in astronomy and astrophysics. It includes detailed tables of the most recent data on: - General constants and units - Atoms, molecules, and spectra - Observational astronomy at all wavelengths from radio to gamma-rays, and neutrinos - Planetary astronomy: Earth, planets and satellites, and solar system small bodies - The Sun, normal stars, and stars with special characteristics - Stellar populations - Cataclysmic and symbiotic variables, supernovae - Theoretical stellar evolution - Circumstellar and interstellar material - Star clusters, galaxies, quasars, and active galactic nuclei ...

Observations of eclipses of UU Sge

Science.gov (United States)

Shimansky, V. V.; Borisov, N. V.; Bikmaev, I. F.; Shimanskaya, N. N.

2012-06-01

We have performed spectroscopy and photometry of eclipses of the pre-cataclysmic variable UUSge using the 6-m telescope of the Special AstrophysicalObservatory and the 1.5-mRussian-Turkish telescope. Our analysis of variations of the B- V and V- R color indices during the eclipses indicates that the temperature of the secondary is T eff,2 = 6000-6300 K. A similar value, T eff,2 = 6200 ± 200 K, follows from our comparison of the observed spectrum of UU Sge at the total eclipse phase and theoretical spectra of late-type stars. We identify 27 absorption lines of 11 chemical elements in the secondary's spectrum. Their abnormal intensities indicate possible high-velocity turbulent motions (up to ξ turb = 10.0 km/s) in the atmosphere of the star and the presence of hot gas above its surface.

Amplification factor variable amplifier

NARCIS (Netherlands)

Akitsugu, Oshita; Nauta, Bram

2010-01-01

PROBLEM TO BE SOLVED: To provide an amplification factor variable amplifier capable of achieving temperature compensation of an amplification factor over a wide variable amplification factor range. ;SOLUTION: A Gilbert type amplification factor variable amplifier 11 amplifies an input signal and can

Eternity Variables to Simulate Specifications

NARCIS (Netherlands)

Hesselink, WH; Boiten, EA; Moller, B

2002-01-01

Simulation of specifications is introduced as a unification and generalization of refinement mappings, history variables, forward simulations, prophecy variables, and backward simulations. Eternity variables are introduced as a more powerful alternative for prophecy variables and backward

[Obstructive Sleep Apnea Syndrom during pregnancy: prevalence of main symptoms and relationship with Pregnancy Induced-Hypertension and Intra-Uterine Growth Retardation].

Science.gov (United States)

Calaora-Tournadre, D; Ragot, S; Meurice, J C; Pourrat, O; D'Halluin, G; Magnin, G; Pierre, F

2006-04-01

To investigate the frequency of main symptoms of Obstructive Sleep Apnea Syndrom (OSAS) and their relationship with Pregnancy Induced-Hypertension (PIH) as well as Intrauterine Growth Retardation (IGR) as suggested by recent studies. Four hundred (and) thirty-eight enquiry forms completed during post-partum period were analysed, after exclusion of multiple pregnancies. Collected data were demographic characteristics, obstetrical events, sleep disorders during last trimester, screening of snoring and vigilance troubles with an Epworth score. Forty-five percentages of the patients reported to have habitual snoring during pregnancy. Among these, 85% were non-snorers before pregnancy. Daytime somnolence concerned 84,5% of the population with an Epworth score significatively increased (P<0,0001). The prevalence of PIH was found to be 4,5%, with two apparently independent risk factors: the body mass index (OR=1,1) and an association between snoring and increased vigilance trouble (OR=2,6). No statistical difference was found concerning IGR. SAS symptoms are frequent during pregnancy and snoring appears to be linked with PIH. However, polysomnographic data are not yet sufficient to explain pathophysiological mechanisms and find relevant diagnostic markers during pregnancy.

Radiological safety of decayed source removal facility (DSRF) - an overview

International Nuclear Information System (INIS)

Rajput, Raksha; George, Jain Reji; Pathak, B.K.

2018-01-01

Industrial radiography is one of the major applications of radioisotope in engineering industry for Non-Destructive Testing (NDT). The equipment used for this purpose is called Industrial Radiography Exposure Device (IGRED) or radiography (RG) camera. In India, more than 1800 IGREDs including imported cameras are being used in NDT industry. These cameras are of different types and have various capacities to house different radioisotopes. Generally, 192 Ir sources are being used for NDT work. The sources are being supplied by BRIT to the users. After the useful period of the utilization of gamma intensity, the decayed source is returned to BRIT in RG camera. The decayed source is removed from the camera in the Decayed Source Removal Facility (DSRF). This facility serves the purpose of a miniature hot-cell with the capability of storing the decayed sources which are removed from the cameras. The empty camera is inspected for its mechanical functions and sent to BRIT's hot-cell for loading the new source. DSRF is situated at BRIT Vashi Complex. This paper deals with the radiological safety in the operation of DSRF for removing decayed sources from industrial radiography cameras

System of radiation monitoring of nuclear hazardous facilities in Institute of Atomic Energy of National Nuclear Centre

International Nuclear Information System (INIS)

Azarov, V.A.; Meshin, M.M.; Shuklin, G.S.

1996-01-01

Issues of radiation monitoring (RM) at reactor complex of Inst. of Atomic Energy (IAE) are discussed in report. The National Nuclear Centre's reactor base consists of 2 complexes situated in 2 different locations: Bajkal-1 and IGR. So far as IAE has common mythology for RM at all hazardous nuclear facilities the issues of RM for Baikal-1 and IGR Radiation monitoring system includes: - personal dosimetric control of personnel, maintaining the reactor systems and research laboratories; RM of industrial buildings; - RM of technical areas of technical area of the facility; sanitary system of dosimetry control (DC); etc. The description of stationary DC system of the complex based on 'System' facility are given. Baikal is surround by sanitary area with radius of 5 km and with its centre in the reactor location. Complexity of studying the radiation status on the territory of Baikal-1 and its surroundings is the result of nuclear testing conducted at the test site in the past, reactor operation with open exhaust of coolant into atmosphere while testing on Nuclear Rocket Engines program as well as global fall out of radionuclides

Variable flexure-based fluid filter

Science.gov (United States)

Brown, Steve B.; Colston, Jr., Billy W.; Marshall, Graham; Wolcott, Duane

2007-03-13

An apparatus and method for filtering particles from a fluid comprises a fluid inlet, a fluid outlet, a variable size passage between the fluid inlet and the fluid outlet, and means for adjusting the size of the variable size passage for filtering the particles from the fluid. An inlet fluid flow stream is introduced to a fixture with a variable size passage. The size of the variable size passage is set so that the fluid passes through the variable size passage but the particles do not pass through the variable size passage.

An Estimate of the Likelihood for a Climatically Significant Volcanic Eruption Within the Present Decade (2000-2009)

Science.gov (United States)

Wilson, Robert M.; Franklin, M. Rose (Technical Monitor)

2000-01-01

Since 1750, the number of cataclysmic volcanic eruptions (i.e., those having a volcanic explosivity index, or VEI, equal to 4 or larger) per decade is found to span 2-11, with 96% located in the tropics and extra-tropical Northern Hemisphere, A two-point moving average of the time series has higher values since the 1860s than before, measuring 8.00 in the 1910s (the highest value) and measuring 6.50 in the 1980s, the highest since the 18 1 0s' peak. On the basis of the usual behavior of the first difference of the two-point moving averages, one infers that the two-point moving average for the 1990s will measure about 6.50 +/- 1.00, implying that about 7 +/- 4 cataclysmic volcanic eruptions should be expected during the present decade (2000-2009). Because cataclysmic volcanic eruptions (especially, those having VEI equal to 5 or larger) nearly always have been associated with episodes of short-term global cooling, the occurrence of even one could ameliorate the effects of global warming. Poisson probability distributions reveal that the probability of one or more VEI equal to 4 or larger events occurring within the next ten years is >99%, while it is about 49% for VEI equal to 5 or larger events and 18% for VEI equal to 6 or larger events. Hence, the likelihood that a, climatically significant volcanic eruption will occur within the next 10 years appears reasonably high.

A novel variable selection approach that iteratively optimizes variable space using weighted binary matrix sampling.

Science.gov (United States)

Deng, Bai-chuan; Yun, Yong-huan; Liang, Yi-zeng; Yi, Lun-zhao

2014-10-07

In this study, a new optimization algorithm called the Variable Iterative Space Shrinkage Approach (VISSA) that is based on the idea of model population analysis (MPA) is proposed for variable selection. Unlike most of the existing optimization methods for variable selection, VISSA statistically evaluates the performance of variable space in each step of optimization. Weighted binary matrix sampling (WBMS) is proposed to generate sub-models that span the variable subspace. Two rules are highlighted during the optimization procedure. First, the variable space shrinks in each step. Second, the new variable space outperforms the previous one. The second rule, which is rarely satisfied in most of the existing methods, is the core of the VISSA strategy. Compared with some promising variable selection methods such as competitive adaptive reweighted sampling (CARS), Monte Carlo uninformative variable elimination (MCUVE) and iteratively retaining informative variables (IRIV), VISSA showed better prediction ability for the calibration of NIR data. In addition, VISSA is user-friendly; only a few insensitive parameters are needed, and the program terminates automatically without any additional conditions. The Matlab codes for implementing VISSA are freely available on the website: https://sourceforge.net/projects/multivariateanalysis/files/VISSA/.

Prikazi procesa poučavanja vjerojatnosti posredstvom igre

OpenAIRE

Gürbüz, Ramazan; Erdem, Emrullah; Uluat, Bedrettin

2014-01-01

The aim of this study is to determine what happens when the subject of probability is taught via educational games. Participants in the research were fourth-grade students (N= 24, aged 9-10) who were taught for 3 class hours (each 40 minutes) by their teacher. The designed games were played among groups of 3-4 students. Data was gathered from 8 selected students’ responses to semi-structured interviews, the teacher’s views about the process, researchers’ evaluations of students’ reflections, ...

Učinak video igre "Flappy Bird" na adolescente

OpenAIRE

Horvat, Marija

2018-01-01

Ovaj diplomski rad nastoji predstaviti uvid u učinke videoigre Flappy Bird na adolescente, fokusirajući se pritom na to potiče li ona nasilno ponašanje te nastoji odgovoriti na pitanje koliko je ta videoigra bila popularna među adolescentima u Hrvatskoj te po čemu je smatraju posebnom, tj. specifičnom. U tu svrhu provedeno je anketno istraživanje, a isti anketni upitnik proveden je na terenu i putem interneta te su uspoređeni rezultati. Anketni upitnik konstruiran je na način da se prvi dio u...

Učenje in razvoj nogometne igre v napadu

OpenAIRE

Gornik, Aljaž

2018-01-01

Nogomet je moštvena športna igra, ki spada v skupino sestavljenih športov. To pomeni, da igra nogometa vsebuje večje število tehničnih in taktičnih elementov z žogo in brez nje. Več kot jih bo posamezni igralec obvladal, boljši bo in lažje bo dosegel medsebojno usklajenost z drugimi soigralci. Večja usklajenost med soigralci pa ustvarja podlago za večje možnosti rezultatskega uspeha moštva. Poleg tehnično-taktične priprave na rezultat v nogometu vplivata tudi kondicijska in psihološka priprav...

The Deployed Warfighter Protection Research Program: Finding New Methods to Vanquish Old Foes (The United States Army Medical Department Journal, April-June 2008)

Science.gov (United States)

2008-06-01

pyriproxyfen, the most powerful insect growth regulator (IGR), against dengue vector mosquitoes. In the Peruvian Amazon community at Iquitos, Stancil42 (Naval...Medical Research Center Detachment, Peru ) received a grant to optimize strategies for preventing the breeding of Aedes aegypti mosquitoes in...effort to prevent sand flies breeding in rodent burrows, the Genesis Company (Wellington, Colorado) won an award for producing insecticidal baits that

U.S. Army Medical Department Journal, April-June 2008

Science.gov (United States)

2008-06-01

IGR), against dengue vector mosquitoes. In the Peruvian Amazon community at Iquitos, Stancil42 (Naval Medical Research Center Detachment, Peru ...Research Unit- Kenya, Nairobi; Naval Medical Research Center Detachment, Lima, Peru ; Naval Medical Research Unit-2, Jakarta, Indonesia; and the Naval...These projects have revealed that sand flies often emerge from the soil beneath tents and camps. In an effort to prevent sand flies breeding in rodent

Climate variability and climate change

International Nuclear Information System (INIS)

Rind, D.

1990-01-01

Changes of variability with climate change are likely to have a substantial impact on vegetation and society, rivaling the importance of changes in the mean values themselves. A variety of paleoclimate and future climate simulations performed with the GISS global climate model is used to assess how the variabilities of temperature and precipitation are altered as climate warms or cools. In general, as climate warms, temperature variability decreases due to reductions in the latitudinal temperature gradient and precipitation variability increases together with the intensity of the hydrologic cycle. If future climate projections are accurate, the reduction in temperature variability will be minimized by the rapid change in mean temperatures, but the hydrologic variability will be amplified by increased evapotranspiration. Greater hydrologic variability would appear to pose a potentially severe problem for the next century

Natural Disasters and Man-Made Catastrophes

Science.gov (United States)

Lonergan, David

2011-01-01

This article categorizes and discusses the kinds of cataclysmic events that threaten the human race and the natural world. A useful set of definitions is provided, and an annotated bibliography of a representative assortment of reference books and monographs.

Several real variables

CERN Document Server

Kantorovitz, Shmuel

2016-01-01

This undergraduate textbook is based on lectures given by the author on the differential and integral calculus of functions of several real variables. The book has a modern approach and includes topics such as: •The p-norms on vector space and their equivalence •The Weierstrass and Stone-Weierstrass approximation theorems •The differential as a linear functional; Jacobians, Hessians, and Taylor's theorem in several variables •The Implicit Function Theorem for a system of equations, proved via Banach’s Fixed Point Theorem •Applications to Ordinary Differential Equations •Line integrals and an introduction to surface integrals This book features numerous examples, detailed proofs, as well as exercises at the end of sections. Many of the exercises have detailed solutions, making the book suitable for self-study. Several Real Variables will be useful for undergraduate students in mathematics who have completed first courses in linear algebra and analysis of one real variable.

Utilization technique on variable speed device

International Nuclear Information System (INIS)

1989-12-01

This reports of workshop on power technology describes using technique on variable speed device, which deals with alternating current situation and prospect of current variable speed device, technical trend and prospect of electronics, reduce expenses by variable speed device, control technique, measurement technology, high voltage variable speed device, recent trend of inverter technology, low voltage and high voltage variable speed device control device, operating variable speed device in cooling fan, FDF application and defect case of variable speed device, cooling pump application of water variable transformer, inverter application and energy effect of ventilation equipment, application of variable speed device and analysis of the result of operation and study for application of variable speed technology.

Effects of insect growth regulators on the nontarget soil arthropod Folsomia candida (Collembola).

Science.gov (United States)

Campiche, S; Becker-van Slooten, K; Ridreau, C; Tarradellas, J

2006-02-01

The aim of this study was to assess the effect of several insect growth regulators (IGRs) on the nontarget soil arthropod Folsomia candida (Collembola). The survival and reproduction rates of F. candida were evaluated after 28 days of exposure to six IGRs (methoprene, fenoxycarb, precocene II, tebufenozide, hexaflumuron and teflubenzuron) and to one herbicide (diuron) in artificial soil. The differences in the sensitivity of F. candida to these different substances are high. The chitin synthesis inhibitors teflubenzuron and hexaflumuron were the most toxic compounds with an EC50 of 0.05 mg/kg (dry weight) for teflubenzuron and an EC50 of 0.6mg/kg for hexaflumuron. Teflubenzuron is toxic for F. candida at concentrations that are probably close to environmental levels of this insecticide. Inhibition of reproduction is strongly related to adult survival for the juvenile hormone agonist methoprene and for the antijuvenile hormone precocene II, with an EC50 of 173 mg/kg and a LC50 of 178mg/kg for methoprene and an EC50 of 15 mg/kg and a LC50 of 26 mg/kg for precocene II. Fenoxycarb, another juvenile hormone analog, showed a dose-response curve for mortality different from that of methoprene; at concentrations such as 3052 mg/kg no effect on adult survival was observed. However, the EC50 value of 113mg/kg is of the same order of magnitude as that obtained for methoprene. A test with compressed soil contaminated with fenoxycarb was conducted to observe parameters such as numbers of eggs laid and juveniles hatched. No differences were observed between these two endpoints for fenoxycarb. An EC50 of 109 mg/kg was obtained for the ecdysone agonist tebufenozide. The herbicide diuron showed a relatively high toxicity for F. candida with an EC50 of 20 mg/kg. Our results show that some of the tested IGRs can have effects on Collembola at environmentally relevant concentrations (toxicity/exposure ratios diuron).

Hard X-ray spectral and timing properties of IGR J17454-2919 consistent with a black hole in the hard state

DEFF Research Database (Denmark)

Tendulkar, Shriharsh P.; Bachetti, Matteo; Tomsick, J.

2014-01-01

frequencies. The Lorentzian has a width of 2 Hz and a fractional rms of 25+/-3%. The hard power-law index, the high energy of the cutoff, and the level of variability all are consistent with properties expected for an accreting black hole in the hard state. While we cannot completely rule out the possibility...... of a low magnetic field neutron star, a black hole is more likely....

Complex variables

CERN Document Server

Fisher, Stephen D

1999-01-01

The most important topics in the theory and application of complex variables receive a thorough, coherent treatment in this introductory text. Intended for undergraduates or graduate students in science, mathematics, and engineering, this volume features hundreds of solved examples, exercises, and applications designed to foster a complete understanding of complex variables as well as an appreciation of their mathematical beauty and elegance. Prerequisites are minimal; a three-semester course in calculus will suffice to prepare students for discussions of these topics: the complex plane, basic

The Taiwanese-American occultation survey project stellar variability. III. Detection of 58 new variable stars

Energy Technology Data Exchange (ETDEWEB)

Ishioka, R.; Wang, S.-Y.; Zhang, Z.-W.; Lehner, M. J.; Cook, K. H.; King, S.-K.; Lee, T.; Marshall, S. L.; Schwamb, M. E.; Wang, J.-H.; Wen, C.-Y. [Institute of Astronomy and Astrophysics, Academia Sinica, 11F of Astronomy-Mathematics Building, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan (China); Alcock, C.; Protopapas, P. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Axelrod, T. [Steward Observatory, 933 North Cherry Avenue, Room N204, Tucson, AZ 85721 (United States); Bianco, F. B. [Center for Cosmology and Particle Physics, New York University, 4 Washington Place, New York, NY 10003 (United States); Byun, Y.-I. [Department of Astronomy and University Observatory, Yonsei University, 134 Shinchon, Seoul 120-749 (Korea, Republic of); Chen, W. P.; Ngeow, C.-C. [Institute of Astronomy, National Central University, No. 300, Jhongda Road, Jhongli City, Taoyuan County 320, Taiwan (China); Kim, D.-W. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Rice, J. A., E-mail: ishioka@asiaa.sinica.edu.tw [Department of Statistics, University of California Berkeley, 367 Evans Hall, Berkeley, CA 94720 (United States)

2014-04-01

The Taiwanese-American Occultation Survey project is designed for the detection of stellar occultations by small-size Kuiper Belt Objects, and it has monitored selected fields along the ecliptic plane by using four telescopes with a 3 deg{sup 2} field of view on the sky since 2005. We have analyzed data accumulated during 2005-2012 to detect variable stars. Sixteen fields with observations of more than 100 epochs were examined. We recovered 85 variables among a total of 158 known variable stars in these 16 fields. Most of the unrecovered variables are located in the fields observed less frequently. We also detected 58 variable stars which are not listed in the International Variable Star Index of the American Association of Variable Star Observers. These variable stars are classified as 3 RR Lyrae, 4 Cepheid, 1 δ Scuti, 5 Mira, 15 semi-regular, and 27 eclipsing binaries based on the periodicity and the profile of the light curves.

Climate variability and climate change

International Nuclear Information System (INIS)

Rind, D.

1991-01-01

Changes of variability with climate change are likely to have a substantial impact on vegetation and society, rivaling the importance of changes in the mean values themselves. A variety of paleoclimate and future climate simulations performed with the GISS global climate model is used to assess how the variabilities of temperature and precipitation are altered as climate warms or cools. In general, as climate warms, temperature variability decreases due to reductions in the latitudinal temperature gradient and precipitation variability increases together with the intensity of the hydrologic cycle. If future climate projections are accurate, the reduction in temperature variability will be minimized by the rapid change in mean temperatures, but the hydrologic variability will be amplified by increased evapotranspiration. Greater hydrologic variability would appear to pose a potentially severe problem for the next century. 19 refs.; 3 figs.; 2 tabs

Variable volume combustor

Science.gov (United States)

Ostebee, Heath Michael; Ziminsky, Willy Steve; Johnson, Thomas Edward; Keener, Christopher Paul

2017-01-17

The present application provides a variable volume combustor for use with a gas turbine engine. The variable volume combustor may include a liner, a number of micro-mixer fuel nozzles positioned within the liner, and a linear actuator so as to maneuver the micro-mixer fuel nozzles axially along the liner.

IRAS variables as galactic structure tracers - Classification of the bright variables

Science.gov (United States)

Allen, L. E.; Kleinmann, S. G.; Weinberg, M. D.

1993-01-01

The characteristics of the 'bright infrared variables' (BIRVs), a sample consisting of the 300 brightest stars in the IRAS Point Source Catalog with IRAS variability index VAR of 98 or greater, are investigated with the purpose of establishing which of IRAS variables are AGB stars (e.g., oxygen-rich Miras and carbon stars, as was assumed by Weinberg (1992)). Results of the analysis of optical, infrared, and microwave spectroscopy of these stars indicate that, out of 88 stars in the BIRV sample identified with cataloged variables, 86 can be classified as Miras. Results of a similar analysis performed for a color-selected sample of stars, using the color limits employed by Habing (1988) to select AGB stars, showed that, out of 52 percent of classified stars, 38 percent are non-AGB stars, including H II regions, planetary nebulae, supergiants, and young stellar objects, indicating that studies using color-selected samples are subject to misinterpretation.

Cataclysmic Rock Avalanche from El Capitan, Yosemite Valley, circa 3.6 ka

Science.gov (United States)

Stock, G. M.

2008-12-01

variability within boulders from this deposit appears to preclude the use of this technique in this setting. Ongoing detailed geologic mapping of the southeast face may help to resolve the source of the rock avalanche.

Classification and prediction of port variables

Energy Technology Data Exchange (ETDEWEB)

Molina Serrano, B.

2016-07-01

Many variables are included in planning and management of port terminals. They can beeconomic, social, environmental and institutional. Agent needs to know relationshipbetween these variables to modify planning conditions. Use of Bayesian Networks allowsfor classifying, predicting and diagnosing these variables. Bayesian Networks allow forestimating subsequent probability of unknown variables, basing on know variables.In planning level, it means that it is not necessary to know all variables because theirrelationships are known. Agent can know interesting information about how port variablesare connected. It can be interpreted as cause-effect relationship. Bayesian Networks can beused to make optimal decisions by introduction of possible actions and utility of theirresults.In proposed methodology, a data base has been generated with more than 40 port variables.They have been classified in economic, social, environmental and institutional variables, inthe same way that smart port studies in Spanish Port System make. From this data base, anetwork has been generated using a non-cyclic conducted grafo which allows for knowingport variable relationships - parents-children relationships-. Obtained network exhibits thateconomic variables are – in cause-effect terms- cause of rest of variable typologies.Economic variables represent parent role in the most of cases. Moreover, whenenvironmental variables are known, obtained network allows for estimating subsequentprobability of social variables.It has been concluded that Bayesian Networks allow for modeling uncertainty in aprobabilistic way, even when number of variables is high as occurs in planning andmanagement of port terminals. (Author)

Changes in heart rate variability and QT variability during the first trimester of pregnancy.

Science.gov (United States)

Carpenter, R E; D'Silva, L A; Emery, S J; Uzun, O; Rassi, D; Lewis, M J

2015-03-01

The risk of new-onset arrhythmia during pregnancy is high, presumably relating to changes in both haemodynamic and cardiac autonomic function. The ability to non-invasively assess an individual's risk of developing arrhythmia during pregnancy would therefore be clinically significant. We aimed to quantify electrocardiographic temporal characteristics during the first trimester of pregnancy and to compare these with non-pregnant controls. Ninety-nine pregnant women and sixty-three non-pregnant women underwent non-invasive cardiovascular and haemodynamic assessment during a protocol consisting of various physiological states (postural manoeurvres, light exercise and metronomic breathing). Variables measured included stroke volume, cardiac output, heart rate, heart rate variability, QT and QT variability and QTVI (a measure of the variability of QT relative to that of RR). Heart rate (p pregnancy only during the supine position (p pregnancy in all physiological states (p pregnancy in all states (p pregnancy is associated with substantial changes in heart rate variability, reflecting a reduction in parasympathetic tone and an increase in sympathetic activity. QTVI shifted to a less favourable value, reflecting a greater than normal amount of QT variability. QTVI appears to be a useful method for quantifying changes in QT variability relative to RR (or heart rate) variability, being sensitive not only to physiological state but also to gestational age. We support the use of non-invasive markers of cardiac electrical variability to evaluate the risk of arrhythmic events in pregnancy, and we recommend the use of multiple physiological states during the assessment protocol.

A variable stiffness joint with electrospun P(VDF-TrFE-CTFE) variable stiffness springs

NARCIS (Netherlands)

Carloni, Raffaella; Lapp, Valerie I.; Cremonese, Andrea; Belcari, Juri; Zucchelli, Andrea

This letter presents a novel rotational variable stiffness joint that relies on one motor and a set of variable stiffness springs. The variable stiffness springs are leaf springs with a layered design, i.e., an electro-active layer of electrospun aligned nanofibers of poly(vinylidene

A theoretical study of problems in classical nova evolution

International Nuclear Information System (INIS)

Shankar, A.

1990-01-01

Three distinct issues in classical nova evolution are addressed with the aid of one- and two-dimensional numerical hydrodynamics. The effects of convection on nova outbursts are examined within the confines of the mixing length theory. It is found that increasing the efficiency of convection enhances the violence of the thermonuclear runaway (TNR). This also relates to the question of the feasibility of obtaining nova outbursts on magnetic white dwarfs among the AM Her systems. The effects of a strong magnetic field on the TNR are explored. The field interferes with the development of convection during the TNR, which results in lower ejection velocities. However, for field strengths typical of cataclysmic variables, the violence of strong outbursts is affected only moderately. The conditions necessary for the production of strong TNR's in the hibernation model of cataclysmic binary evolution are also examined. The feasibility of obtaining strong nova outbursts is investigated when the accretion rate during hibernation is decreased. It is found that a reduction (by a factor of 100) for periods of longer than a couple thousand years, is sufficient to ensure violent outbursts, even in the presence of large pre-outburst accretion rates. The effects of a common envelope phase (CEP) on the outburst are discussed. The motion of the secondary through an expanding common envelope is resisted by frictional drag. This dissipates both energy and angular momentum from the orbit inducing hydrodynamic motion. Significant departures are found to occur in the manner in which mass is lost when the effects of drag are taken into account. Specifically, a CEP is found to accelerate and enhance mass loss. Ejection is found to be concentrated in the orbital plane, with velocities of a few thousand km/sec

Examining Impulse-Variability in Kicking.

Science.gov (United States)

Chappell, Andrew; Molina, Sergio L; McKibben, Jonathon; Stodden, David F

2016-07-01

This study examined variability in kicking speed and spatial accuracy to test the impulse-variability theory prediction of an inverted-U function and the speed-accuracy trade-off. Twenty-eight 18- to 25-year-old adults kicked a playground ball at various percentages (50-100%) of their maximum speed at a wall target. Speed variability and spatial error were analyzed using repeated-measures ANOVA with built-in polynomial contrasts. Results indicated a significant inverse linear trajectory for speed variability (p < .001, η2= .345) where 50% and 60% maximum speed had significantly higher variability than the 100% condition. A significant quadratic fit was found for spatial error scores of mean radial error (p < .0001, η2 = .474) and subject-centroid radial error (p < .0001, η2 = .453). Findings suggest variability and accuracy of multijoint, ballistic skill performance may not follow the general principles of impulse-variability theory or the speed-accuracy trade-off.

Improved variable reduction in partial least squares modelling by Global-Minimum Error Uninformative-Variable Elimination.

Science.gov (United States)

Andries, Jan P M; Vander Heyden, Yvan; Buydens, Lutgarde M C

2017-08-22

The calibration performance of Partial Least Squares regression (PLS) can be improved by eliminating uninformative variables. For PLS, many variable elimination methods have been developed. One is the Uninformative-Variable Elimination for PLS (UVE-PLS). However, the number of variables retained by UVE-PLS is usually still large. In UVE-PLS, variable elimination is repeated as long as the root mean squared error of cross validation (RMSECV) is decreasing. The set of variables in this first local minimum is retained. In this paper, a modification of UVE-PLS is proposed and investigated, in which UVE is repeated until no further reduction in variables is possible, followed by a search for the global RMSECV minimum. The method is called Global-Minimum Error Uninformative-Variable Elimination for PLS, denoted as GME-UVE-PLS or simply GME-UVE. After each iteration, the predictive ability of the PLS model, built with the remaining variable set, is assessed by RMSECV. The variable set with the global RMSECV minimum is then finally selected. The goal is to obtain smaller sets of variables with similar or improved predictability than those from the classical UVE-PLS method. The performance of the GME-UVE-PLS method is investigated using four data sets, i.e. a simulated set, NIR and NMR spectra, and a theoretical molecular descriptors set, resulting in twelve profile-response (X-y) calibrations. The selective and predictive performances of the models resulting from GME-UVE-PLS are statistically compared to those from UVE-PLS and 1-step UVE, one-sided paired t-tests. The results demonstrate that variable reduction with the proposed GME-UVE-PLS method, usually eliminates significantly more variables than the classical UVE-PLS, while the predictive abilities of the resulting models are better. With GME-UVE-PLS, a lower number of uninformative variables, without a chemical meaning for the response, may be retained than with UVE-PLS. The selectivity of the classical UVE method

Ultrasonic variables affecting inspection

International Nuclear Information System (INIS)

Lautzenheiser, C.E.; Whiting, A.R.; McElroy, J.T.

1977-01-01

There are many variables which affect the detection of the effects and reproducibility of results when utilizing ultrasonic techniques. The most important variable is the procedure, as this document specifies, to a great extent, the controls that are exercised over the other variables. The most important variable is personnel with regards to training, qualification, integrity, data recording, and data analysis. Although the data is very limited, these data indicate that, if the procedure is carefully controlled, reliability of defect detection and reproducibility of results are both approximately 90 percent for reliability of detection, this applies to relatively small defects as reliability increases substantially as defect size increases above the recording limit. (author)

Investigating Factorial Invariance of Latent Variables Across Populations When Manifest Variables Are Missing Completely.

Science.gov (United States)

Widaman, Keith F; Grimm, Kevin J; Early, Dawnté R; Robins, Richard W; Conger, Rand D

2013-07-01

Difficulties arise in multiple-group evaluations of factorial invariance if particular manifest variables are missing completely in certain groups. Ad hoc analytic alternatives can be used in such situations (e.g., deleting manifest variables), but some common approaches, such as multiple imputation, are not viable. At least 3 solutions to this problem are viable: analyzing differing sets of variables across groups, using pattern mixture approaches, and a new method using random number generation. The latter solution, proposed in this article, is to generate pseudo-random normal deviates for all observations for manifest variables that are missing completely in a given sample and then to specify multiple-group models in a way that respects the random nature of these values. An empirical example is presented in detail comparing the 3 approaches. The proposed solution can enable quantitative comparisons at the latent variable level between groups using programs that require the same number of manifest variables in each group.

Variability in ACL tunnel placement: observational clinical study of surgeon ACL tunnel variability.

Science.gov (United States)

Wolf, Brian R; Ramme, Austin J; Wright, Rick W; Brophy, Robert H; McCarty, Eric C; Vidal, Armando R; Parker, Richard D; Andrish, Jack T; Amendola, Annunziato

2013-06-01

Multicenter and multisurgeon cohort studies on anterior cruciate ligament (ACL) reconstruction are becoming more common. Minimal information exists on intersurgeon and intrasurgeon variability in ACL tunnel placement. Purpose/ The purpose of this study was to analyze intersurgeon and intrasurgeon variability in ACL tunnel placement in a series of The Multicenter Orthopaedic Outcomes Network (MOON) ACL reconstruction patients and in a clinical cohort of ACL reconstruction patients. The hypothesis was that there would be minimal variability between surgeons in ACL tunnel placement. Cross-sectional study; Level of evidence, 3. Seventy-eight patients who underwent ACL reconstruction by 8 surgeons had postoperative imaging with computed tomography, and ACL tunnel location and angulation were analyzed using 3-dimensional surface processing and measurement. Intersurgeon and intrasurgeon variability in ACL tunnel placement was analyzed. For intersurgeon variability, the range in mean ACL femoral tunnel depth between surgeons was 22%. For femoral tunnel height, there was a 19% range. Tibial tunnel location from anterior to posterior on the plateau had a 16% range in mean results. There was only a small range of 4% for mean tibial tunnel location from the medial to lateral dimension. For intrasurgeon variability, femoral tunnel depth demonstrated the largest ranges, and tibial tunnel location from medial to lateral on the plateau demonstrated the least variability. Overall, surgeons were relatively consistent within their own cases. Using applied measurement criteria, 85% of femoral tunnels and 90% of tibial tunnels fell within applied literature-based guidelines. Ninety-one percent of the axes of the femoral tunnels fell within the boundaries of the femoral footprint. The data demonstrate that surgeons performing ACL reconstructions are relatively consistent between each other. There is, however, variability of average tunnel placement up to 22% of mean condylar depth

Hope for Environmental Action

Science.gov (United States)

Fleischer, Barbara J.; DeMoor, Emily

2015-01-01

Environmental consciousness-raising programs tend to emphasize the magnitude of imminent ecological disasters, if humans continue on their current trajectory. While these environmental literacy programs also call for action to avoid cataclysmic ecological changes, psychological research on "learned helplessness" suggests that information…

Russian Federation : From the first to second demographic transition

NARCIS (Netherlands)

Zakharov, Sergei

2008-01-01

The demographic transition in Russia was accelerated by several social cataclysms during the "Soviet type" modernization. Frequent changes in the timing of births and marriages engendered a mass "abortion culture". Contraceptive devices of poor quality were produced on a limited scale. The Soviet

High-dispersion observations of H-alpha in the suspected brown dwarf, white dwarf binary system G29-38

International Nuclear Information System (INIS)

Liebert, J.; Saffer, R.A.; Pilachowski, C.A.

1989-01-01

High-dispersion spectroscopy of the H-alpha absorption line of the cool DA white dwarf G29-38 is reported. This is the star for which a recently detected IR excess has been suggested to be due to a possible brown dwarf companion. Three echelle spectra show no evidence for radial-velocity variations larger than about 1.1 + or - 8.7 km/s and are used to derive a weighted heliocentric radial velocity of 33.7 + or - 4.3 kms/s for the white dwarf. The observations of a sharp absorption-line core restricts the possible rotation of the white dwarf to 40 km/s or less and ensures that any surface magnetic field has a strength of 100,000 G or less. These results make it unlikely that the DA white dwarf has previously been in a cataclysmic variable accretion phase. 18 references

Circular polarimetry of EXO 033319-2554.2 - a new eclipsing AM Herculis star

International Nuclear Information System (INIS)

Berriman, G.; Smith, P.S.

1988-01-01

This Letter presents circular polarimetry that unequivocally identifies EXO 033319-2554.2 as only the third eclipsing AM Her star and brings the total number of AM Her stars now identified to 14. The orbital period is 126.4 minutes, as previously reported, and defines a new short-period edge to the period gap seen in all classes of cataclysmic variable stars. EXO 033319-2554.2 shows 2.5 mag deep eclipses of the predominantly accreting magnetic pole on the white dwarf. Before the eclipse, the pole rotates into the line of sight and shows white-light circular polarization, due to cyclotron radiation, that reaches values as high as 10 percent. There is some evidence that the second pole is emitting cyclotron radiation too. How high time resolution photometry, linear polarimetry, and spectroscopy will be of great value in understanding this system. 17 references

Spectroscopy of the red star in IP Peg

International Nuclear Information System (INIS)

Martin, J.S.; Jones, D.H.P.; Friend, M.T.; Smith, R.C.

1989-01-01

CCD spectroscopy of the cataclysmic variable IP Pegasi during decline from outburst shows narrow chromospheric emission lines from the irradiated face of the red star. The He I (7065 A) emission line is used to produce a partial radial velocity curve, with K He =293.2±3.3 km s -1 . A reanalysis of previous Na I doublet (8190 A) absorption line data produces a considerably larger semi-amplitude, K abs , than previously published. However, this is larger than the true semi-amplitude, K 2 , because irradiation from the disc ionizes the NaI on the inner face of the red star and decreases the strength of the NaI doublet on that face. A computer simulation of the secondary radial velocity curve, including this ionization effect, is used to estimate the true semi-amplitude of the secondary motion. This gives K 2 =298±8 km s -1 . (author)

Self-Organized Criticality in Astrophysics The Statistics of Nonlinear Processes in the Universe

CERN Document Server

Aschwanden, Markus

2011-01-01

The concept of ‘self-organized criticality’ (SOC) has been applied to a variety of problems, ranging from population growth and traffic jams to earthquakes, landslides and forest fires. The technique is now being applied to a wide range of phenomena in astrophysics, such as planetary magnetospheres, solar flares, cataclysmic variable stars, accretion disks, black holes and gamma-ray bursts, and also to phenomena in galactic physics and cosmology. Self-organized Criticality in Astrophysics introduces the concept of SOC and shows that, due to its universality and ubiquity, it is a law of nature. The theoretical framework and specific physical models are described, together with a range of applications in various aspects of astrophyics. The mathematical techniques, including the statistics of random processes, time series analysis, time scale and waiting time distributions, are presented and the results are applied to specific observations of astrophysical phenomena.

Observational constraints on the inter-binary stellar flare hypothesis for the gamma-ray bursts

Science.gov (United States)

Rao, A. R.; Vahia, M. N.

1994-01-01

The Gamma Ray Observatory/Burst and Transient Source Experiment (GRO/BATSE) results on the Gamma Ray Bursts (GRBs) have given an internally consistent set of observations of about 260 GRBs which have been released for analysis by the BATSE team. Using this database we investigate our earlier suggestion (Vahia and Rao, 1988) that GRBs are inter-binary stellar flares from a group of objects classified as Magnetically Active Stellar Systems (MASS) which includes flare stars, RS CVn binaries and cataclysmic variables. We show that there exists an observationally consistent parameter space for the number density, scale height and flare luminosity of MASS which explains the complete log(N) - log(P) distribution of GRBs as also the observed isotropic distribution. We further use this model to predict anisotropy in the GRB distribution at intermediate luminosities. We make definite predictions under the stellar flare hypothesis that can be tested in the near future.

Benchmarking Variable Selection in QSAR.

Science.gov (United States)

Eklund, Martin; Norinder, Ulf; Boyer, Scott; Carlsson, Lars

2012-02-01

Variable selection is important in QSAR modeling since it can improve model performance and transparency, as well as reduce the computational cost of model fitting and predictions. Which variable selection methods that perform well in QSAR settings is largely unknown. To address this question we, in a total of 1728 benchmarking experiments, rigorously investigated how eight variable selection methods affect the predictive performance and transparency of random forest models fitted to seven QSAR datasets covering different endpoints, descriptors sets, types of response variables, and number of chemical compounds. The results show that univariate variable selection methods are suboptimal and that the number of variables in the benchmarked datasets can be reduced with about 60 % without significant loss in model performance when using multivariate adaptive regression splines MARS and forward selection. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Toxicity Assessment of Buprofezin, Lufenuron, and Triflumuron to the Earthworm Aporrectodea caliginosa

OpenAIRE

Badawy, Mohamed E. I.; Kenawy, Anter; El-Aswad, Ahmed F.

2013-01-01

Earthworms are particularly important soil macroinvertebrates and are often used in assessing the general impact of pesticide pollution in soil. The present study was conducted in order to investigate the toxicity of three insect growth regulators (IGRs) buprofezin, lufenuron, and triflumuron, at different application rates and exposure times toward mature earthworms Aporrectodea caliginosa. The effects of these pesticides on the growth rate in relation to the activities of acetylcholinestera...

The Performance of Variable Annuities

OpenAIRE

Michael J. McNamara; Henry R. Oppenheimer

1991-01-01

Variable annuities have become increasingly important in retirement plans. This paper provides an examination of the investment performance of variable annuities for the period year-end 1973 to year-end 1988. Returns, risk, and selectivity measures are analyzed for the sample of annuities, for individual variable annuities, and for subsamples of annuities with similar portfolio size and turnover. While the investment returns of variable annuities were greater than inflation over the period, t...

Markets, Distribution, and Exchange after Societal Cataclysm

Science.gov (United States)

1988-03-01

the governing bodies of institutions such as stock and commodity exchanges, corporations, and professional associations at the micro level. The intimate...routes of economic recovery fully, a complementary understanding of these various perspectives is required. At a more micro -level of analysis, further...Secretaire d’Administration, Ministere de l’Interieur, Direction Generale de la Protection Civile, rue de Louvain, 1, 1000 Brussels, BELGIUM 212. Servicio

Validity of a Residualized Dependent Variable after Pretest Covariance Adjustments: Still the Same Variable?

Science.gov (United States)

Nimon, Kim; Henson, Robin K.

2015-01-01

The authors empirically examined whether the validity of a residualized dependent variable after covariance adjustment is comparable to that of the original variable of interest. When variance of a dependent variable is removed as a result of one or more covariates, the residual variance may not reflect the same meaning. Using the pretest-posttest…

Confounding of three binary-variables counterfactual model

OpenAIRE

Liu, Jingwei; Hu, Shuang

2011-01-01

Confounding of three binary-variables counterfactual model is discussed in this paper. According to the effect between the control variable and the covariate variable, we investigate three counterfactual models: the control variable is independent of the covariate variable, the control variable has the effect on the covariate variable and the covariate variable affects the control variable. Using the ancillary information based on conditional independence hypotheses, the sufficient conditions...

Photometry of the SW Sextantis-type nova-like BH Lyncis in high state

Science.gov (United States)

Stanishev, V.; Kraicheva, Z.; Genkov, V.

2006-08-01

Aims.We present a photometric study of the deeply eclipsing SW Sex-type nova-like cataclysmic variable star BH Lyn. Methods: .Time-resolved V-band CCD photometry was obtained for seven nights between 1999 and 2004. Results: .We determined 11 new eclipse timings of BH Lyn and derived a refined orbital ephemeris with an orbital period of 0.155875577(14) °. During the observations, BH Lyn was in high-state with V≃15.5 mag. The star presents ~1.5 mag deep eclipses with mean full-width at half-flux of 0.0683(±0.0054)P_orb. The eclipse shape is highly variable, even changing form cycle to cycle. This is most likely due to accretion disc surface brightness distribution variations, most probably caused by strong flickering. Time-dependent accretion disc self-occultation or variations of the hot spot(s) intensity are also possible explanations. Negative superhumps with period of ˜0.145 ° are detected in two long runs in 2000. A possible connection between SW Sex and negative superhump phenomena through the presence of tilted accretion disc is discussed, and a way to observationally test this is suggested.

Using Astrometrica to Teach an Introduction to Asteroid and Comet Astrometry

Science.gov (United States)

Durig, Douglas T.

2007-05-01

We have organized a Consortium for Astronomy Research and Teaching (CART) with several small colleges and universities from the Appalachian Colleges Association (ACA). In 2006 we received a small grant from the ACA Teaching and Learning Conference to develop laboratory exercises using the on-line telescopes of the Cordell-Lorenz Observatory of The University of the South in Sewanee, TN. We have completed and tested the first two, Asteroid Astrometry and Comet Astronomy and Angular Size. We are continuing to develop several more on the HR Diagram, Cataclysmic Variables and Short Period Variable Stars. We had unknown new asteroids in the field of view the first four times we performed the Asteroid Astrometry exercise but, unfortunately, none of the students recognized the new objects. However, they were more motivated to perform the exercise because of the opportunity to discover the new objects and they performed better on the review questions than students doing a comparable virtual exercise. Both of the astrometry exercises use the Astrometrica program developed by Herbert Raab and provide an introduction to the use and applications of this very functional shareware program. The program is available for free to educators.

Variable-spot ion beam figuring

International Nuclear Information System (INIS)

Wu, Lixiang; Qiu, Keqiang; Fu, Shaojun

2016-01-01

This paper introduces a new scheme of ion beam figuring (IBF), or rather variable-spot IBF, which is conducted at a constant scanning velocity with variable-spot ion beam collimated by a variable diaphragm. It aims at improving the reachability and adaptation of the figuring process within the limits of machine dynamics by varying the ion beam spot size instead of the scanning velocity. In contrast to the dwell time algorithm in the conventional IBF, the variable-spot IBF adopts a new algorithm, which consists of the scan path programming and the trajectory optimization using pattern search. In this algorithm, instead of the dwell time, a new concept, integral etching time, is proposed to interpret the process of variable-spot IBF. We conducted simulations to verify its feasibility and practicality. The simulation results indicate the variable-spot IBF is a promising alternative to the conventional approach.

A study of variable thrust, variable specific impulse trajectories for solar system exploration

Science.gov (United States)

Sakai, Tadashi

A study has been performed to determine the advantages and disadvantages of variable thrust and variable Isp (specific impulse) trajectories for solar system exploration. There have been several numerical research efforts for variable thrust, variable Isp, power-limited trajectory optimization problems. All of these results conclude that variable thrust, variable Isp (variable specific impulse, or VSI) engines are superior to constant thrust, constant Isp (constant specific impulse; or CSI) engines. However, most of these research efforts assume a mission from Earth to Mars, and some of them further assume that these planets are circular and coplanar. Hence they still lack the generality. This research has been conducted to answer the following questions: (1) Is a VSI engine always better than a CSI engine or a high thrust engine for any mission to any planet with any time of flight considering lower propellant mass as the sole criterion? (2) If a planetary swing-by is used for a VSI trajectory, is the fuel savings of a VSI swing-by trajectory better than that of a CSI swing-by or high thrust swing-by trajectory? To support this research, an unique, new computer-based interplanetary trajectory calculation program has been created. This program utilizes a calculus of variations algorithm to perform overall optimization of thrust, Isp, and thrust vector direction along a trajectory that minimizes fuel consumption for interplanetary travel. It is assumed that the propulsion system is power-limited, and thus the compromise between thrust and Isp is a variable to be optimized along the flight path. This program is capable of optimizing not only variable thrust trajectories but also constant thrust trajectories in 3-D space using a planetary ephemeris database. It is also capable of conducting planetary swing-bys. Using this program, various Earth-originating trajectories have been investigated and the optimized results have been compared to traditional CSI and high

Continuous-variable quantum homomorphic signature

Science.gov (United States)

Li, Ke; Shang, Tao; Liu, Jian-wei

2017-10-01

Quantum cryptography is believed to be unconditionally secure because its security is ensured by physical laws rather than computational complexity. According to spectrum characteristic, quantum information can be classified into two categories, namely discrete variables and continuous variables. Continuous-variable quantum protocols have gained much attention for their ability to transmit more information with lower cost. To verify the identities of different data sources in a quantum network, we propose a continuous-variable quantum homomorphic signature scheme. It is based on continuous-variable entanglement swapping and provides additive and subtractive homomorphism. Security analysis shows the proposed scheme is secure against replay, forgery and repudiation. Even under nonideal conditions, it supports effective verification within a certain verification threshold.

Pulsating red variables

International Nuclear Information System (INIS)

Whitelock, P.A.

1990-01-01

The observational characteristics of pulsating red variables are reviewed with particular emphasis on the Miras. These variables represent the last stage in the evolution of stars on the Asymptotic Giant Branch (AGB). A large fraction of the IRAS sources in the Bulge are Mira variables and a subset of these are also OH/IR sources. Their periods range up to 720 days, though most are between 360 and 560 days. At a given period those stars with the highest pulsation amplitudes have the highest mass-loss rates; this is interpreted as evidence for a causal connection between mass-loss and pulsation. It is suggested that once an AGB star has become a Mira it will evolve with increasing pulsation amplitude and mass-loss, but with very little change of luminosity or logarithmic period. 26 refs

Imaging Variable Stars with HST

Science.gov (United States)

Karovska, M.

2012-06-01

(Abstract only) The Hubble Space Telescope (HST) observations of astronomical sources, ranging from objects in our solar system to objects in the early Universe, have revolutionized our knowledge of the Universe its origins and contents. I highlight results from HST observations of variable stars obtained during the past twenty or so years. Multiwavelength observations of numerous variable stars and stellar systems were obtained using the superb HST imaging capabilities and its unprecedented angular resolution, especially in the UV and optical. The HST provided the first detailed images probing the structure of variable stars including their atmospheres and circumstellar environments. AAVSO observations and light curves have been critical for scheduling of many of these observations and provided important information and context for understanding of the imaging results of many variable sources. I describe the scientific results from the imaging observations of variable stars including AGBs, Miras, Cepheids, semiregular variables (including supergiants and giants), YSOs and interacting stellar systems with a variable stellar components. These results have led to an unprecedented understanding of the spatial and temporal characteristics of these objects and their place in the stellar evolutionary chains, and in the larger context of the dynamic evolving Universe.

(Super Variable Costing-Throughput Costing)

OpenAIRE

Çakıcı, Cemal

2006-01-01

(Super Variable Costing-Throughput Costing) The aim of this study is to explain the super-variable costing method which is a new subject in cost and management accounting and to show it’s working practicly.Shortly, super-variable costing can be defined as a costing method which is use only direct material costs in calculate of product costs and treats all costs except these (direct labor and overhead) as periad costs or operating costs.By using super-variable costing method, product costs ar...

Examining the causes of memory strength variability: recollection, attention failure, or encoding variability?

Science.gov (United States)

Koen, Joshua D; Aly, Mariam; Wang, Wei-Chun; Yonelinas, Andrew P

2013-11-01

A prominent finding in recognition memory is that studied items are associated with more variability in memory strength than new items. Here, we test 3 competing theories for why this occurs-the encoding variability, attention failure, and recollection accounts. Distinguishing among these theories is critical because each provides a fundamentally different account of the processes underlying recognition memory. The encoding variability and attention failure accounts propose that old item variance will be unaffected by retrieval manipulations because the processes producing this effect are ascribed to encoding. The recollection account predicts that both encoding and retrieval manipulations that preferentially affect recollection will affect memory variability. These contrasting predictions were tested by examining the effect of response speeding (Experiment 1), dividing attention at retrieval (Experiment 2), context reinstatement (Experiment 3), and increased test delay (Experiment 4) on recognition performance. The results of all 4 experiments confirm the predictions of the recollection account and are inconsistent with the encoding variability account. The evidence supporting the attention failure account is mixed, with 2 of the 4 experiments confirming the account and 2 disconfirming the account. These results indicate that encoding variability and attention failure are insufficient accounts of memory variance and provide support for the recollection account. Several alternative theoretical accounts of the results are also considered. PsycINFO Database Record (c) 2013 APA, all rights reserved.

Preservice Teachers' Understanding of Variable

Science.gov (United States)

Brown, Sue; Bergman, Judy

2013-01-01

This study examines the research on middle school students' understanding of variables and explores preservice elementary and middle school teachers' knowledge of variables. According to research studies, middle school students have limited understanding of variables. Many studies have examined the performance of middle school students and offered…

The Necessary Evil of Preventive Detention: A Plan for a More Moderate and Sustainable Solution

Science.gov (United States)

2008-07-01

Malaysia and Singapore have preventive detention regimes in which they can hold suspects for two-year periods without charge or meaningful court...have the leisure , turn their considerable talents to 212 deliberating how to fix a strained and mismatched legal system, before another cataclysm

Biological Sampling Variability Study

Energy Technology Data Exchange (ETDEWEB)

Amidan, Brett G. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hutchison, Janine R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2016-11-08

There are many sources of variability that exist in the sample collection and analysis process. This paper addresses many, but not all, sources of variability. The main focus of this paper was to better understand and estimate variability due to differences between samplers. Variability between days was also studied, as well as random variability within each sampler. Experiments were performed using multiple surface materials (ceramic and stainless steel), multiple contaminant concentrations (10 spores and 100 spores), and with and without the presence of interfering material. All testing was done with sponge sticks using 10-inch by 10-inch coupons. Bacillus atrophaeus was used as the BA surrogate. Spores were deposited using wet deposition. Grime was coated on the coupons which were planned to include the interfering material (Section 3.3). Samples were prepared and analyzed at PNNL using CDC protocol (Section 3.4) and then cultured and counted. Five samplers were trained so that samples were taken using the same protocol. Each sampler randomly sampled eight coupons each day, four coupons with 10 spores deposited and four coupons with 100 spores deposited. Each day consisted of one material being tested. The clean samples (no interfering materials) were run first, followed by the dirty samples (coated with interfering material). There was a significant difference in recovery efficiency between the coupons with 10 spores deposited (mean of 48.9%) and those with 100 spores deposited (mean of 59.8%). There was no general significant difference between the clean and dirty (containing interfering material) coupons or between the two surface materials; however, there was a significant interaction between concentration amount and presence of interfering material. The recovery efficiency was close to the same for coupons with 10 spores deposited, but for the coupons with 100 spores deposited, the recovery efficiency for the dirty samples was significantly larger (65

Gait variability measurements in lumbar spinal stenosis patients: part B. Preoperative versus postoperative gait variability

International Nuclear Information System (INIS)

Papadakis, N C; Christakis, D G; Tzagarakis, G N; Chlouverakis, G I; Kampanis, N A; Stergiopoulos, K N; Katonis, P G

2009-01-01

The objective of this study was to assess the gait variability of lumbar spinal stenosis (LSS) patients and to evaluate its postoperative progression. The hypothesis was that LSS patients' preoperative gait variability in the frequency domain was higher than the corresponding postoperative. A tri-axial accelerometer sensor was used for the gait measurement and a spectral differential entropy algorithm was used to measure the gait variability. Twelve subjects with LSS were measured before and after surgery. Preoperative measurements were performed 2 days before surgery. Postoperative measurements were performed 6 and 12 months after surgery. Preoperative gait variability was higher than the corresponding postoperative. Also, in most cases, gait variability appeared to decrease throughout the year

High-p{sub T} B-tagging and top-tagging with variable-R jets in ATLAS

Energy Technology Data Exchange (ETDEWEB)

Behr, Katharina [Sub-department of Particle Physics, University of Oxford, Denys-Wilkinson Building, Keble Road, Oxford OX1 3RH (United Kingdom)

2015-07-01

Variable-R jets, whose effective size is inversely proportional to their transverse momentum, are a versatile tool for object reconstruction across the large transverse momentum regime accessible during Run 2 of the LHC. I discuss the performance of Variable-R jets in two different contexts: (1) Boosted top-tagging. The separation between the decay products of highly energetic top quarks decreases with p{sub T}{sup top} causing them to overlap and merge into a single jet. Taggers relying on large fixed-R jets overestimate the real size of the top jet in the highly boosted regime and are more susceptible to the effects of pile-up. Variable-R jets are studied as the basis for more natural taggers which may not even require grooming. (2) B-tagging. The b-tagging performance in boosted topologies suffers in the presence of close-by jets. This limits the sensitivity of many searches such as those in boosted hh → 4b final states. New b-taggers relying on track jets with smaller sizes than the traditional R=0.4 to better isolate the b-hadron decay show significant improvements in highly boosted scenarios but perform worse at low transverse momenta where they fail to capture the full b-jet. Variable-R track jets provide a unified approach to b-tagging in both p{sub T} regimes.

Evolution of variable stars

International Nuclear Information System (INIS)

Becker, S.A.

1986-08-01

Throughout the domain of the H R diagram lie groupings of stars whose luminosity varies with time. These variable stars can be classified based on their observed properties into distinct types such as β Cephei stars, δ Cephei stars, and Miras, as well as many other categories. The underlying mechanism for the variability is generally felt to be due to four different causes: geometric effects, rotation, eruptive processes, and pulsation. In this review the focus will be on pulsation variables and how the theory of stellar evolution can be used to explain how the various regions of variability on the H R diagram are populated. To this end a generalized discussion of the evolutionary behavior of a massive star, an intermediate mass star, and a low mass star will be presented. 19 refs., 1 fig., 1 tab

Intelligent control for large-scale variable speed variable pitch wind turbines

Institute of Scientific and Technical Information of China (English)

Xinfang ZHANG; Daping XU; Yibing LIU

2004-01-01

Large-scale wind turbine generator systems have strong nonlinear multivariable characteristics with many uncertain factors and disturbances.Automatic control is crucial for the efficiency and reliability of wind turbines.On the basis of simplified and proper model of variable speed variable pitch wind turbines,the effective wind speed is estimated using extended Kalman filter.Intelligent control schemes proposed in the paper include two loops which operate in synchronism with each other.At below-rated wind speed,the inner loop adopts adaptive fuzzy control based on variable universe for generator torque regulation to realize maximum wind energy capture.At above-rated wind speed, a controller based on least square support vector machine is proposed to adjust pitch angle and keep rated output power.The simulation shows the effectiveness of the intelligent control.

Rapidly variable relatvistic absorption

Science.gov (United States)

Parker, M.; Pinto, C.; Fabian, A.; Lohfink, A.; Buisson, D.; Alston, W.; Jiang, J.

2017-10-01

I will present results from the 1.5Ms XMM-Newton observing campaign on the most X-ray variable AGN, IRAS 13224-3809. We find a series of nine absorption lines with a velocity of 0.24c from an ultra-fast outflow. For the first time, we are able to see extremely rapid variability of the UFO features, and can link this to the X-ray variability from the inner accretion disk. We find a clear flux dependence of the outflow features, suggesting that the wind is ionized by increasing X-ray emission.

Reward-dependent modulation of movement variability.

Science.gov (United States)

Pekny, Sarah E; Izawa, Jun; Shadmehr, Reza

2015-03-04

Movement variability is often considered an unwanted byproduct of a noisy nervous system. However, variability can signal a form of implicit exploration, indicating that the nervous system is intentionally varying the motor commands in search of actions that yield the greatest success. Here, we investigated the role of the human basal ganglia in controlling reward-dependent motor variability as measured by trial-to-trial changes in performance during a reaching task. We designed an experiment in which the only performance feedback was success or failure and quantified how reach variability was modulated as a function of the probability of reward. In healthy controls, reach variability increased as the probability of reward decreased. Control of variability depended on the history of past rewards, with the largest trial-to-trial changes occurring immediately after an unrewarded trial. In contrast, in participants with Parkinson's disease, a known example of basal ganglia dysfunction, reward was a poor modulator of variability; that is, the patients showed an impaired ability to increase variability in response to decreases in the probability of reward. This was despite the fact that, after rewarded trials, reach variability in the patients was comparable to healthy controls. In summary, we found that movement variability is partially a form of exploration driven by the recent history of rewards. When the function of the human basal ganglia is compromised, the reward-dependent control of movement variability is impaired, particularly affecting the ability to increase variability after unsuccessful outcomes. Copyright © 2015 the authors 0270-6474/15/354015-10$15.00/0.

Machine learning search for variable stars

Science.gov (United States)

Pashchenko, Ilya N.; Sokolovsky, Kirill V.; Gavras, Panagiotis

2018-04-01

Photometric variability detection is often considered as a hypothesis testing problem: an object is variable if the null hypothesis that its brightness is constant can be ruled out given the measurements and their uncertainties. The practical applicability of this approach is limited by uncorrected systematic errors. We propose a new variability detection technique sensitive to a wide range of variability types while being robust to outliers and underestimated measurement uncertainties. We consider variability detection as a classification problem that can be approached with machine learning. Logistic Regression (LR), Support Vector Machines (SVM), k Nearest Neighbours (kNN), Neural Nets (NN), Random Forests (RF), and Stochastic Gradient Boosting classifier (SGB) are applied to 18 features (variability indices) quantifying scatter and/or correlation between points in a light curve. We use a subset of Optical Gravitational Lensing Experiment phase two (OGLE-II) Large Magellanic Cloud (LMC) photometry (30 265 light curves) that was searched for variability using traditional methods (168 known variable objects) as the training set and then apply the NN to a new test set of 31 798 OGLE-II LMC light curves. Among 205 candidates selected in the test set, 178 are real variables, while 13 low-amplitude variables are new discoveries. The machine learning classifiers considered are found to be more efficient (select more variables and fewer false candidates) compared to traditional techniques using individual variability indices or their linear combination. The NN, SGB, SVM, and RF show a higher efficiency compared to LR and kNN.

How to get rid of W: a latent variables approach to modelling spatially lagged variables

NARCIS (Netherlands)

Folmer, H.; Oud, J.

2008-01-01

In this paper we propose a structural equation model (SEM) with latent variables to model spatial dependence. Rather than using the spatial weights matrix W, we propose to use latent variables to represent spatial dependence and spillover effects, of which the observed spatially lagged variables are

How to get rid of W : a latent variables approach to modelling spatially lagged variables

NARCIS (Netherlands)

Folmer, Henk; Oud, Johan

2008-01-01

In this paper we propose a structural equation model (SEM) with latent variables to model spatial dependence. Rather than using the spatial weights matrix W, we propose to use latent variables to represent spatial dependence and spillover effects, of which the observed spatially lagged variables are

Action threshold for applying insect growth regulators to tomato for management of irregular ripening caused by Bemisia argentifolii (Homoptera: Aleyrodidae).

Science.gov (United States)

Schuster, D J

2002-04-01

The whitefly Bemisia argentifolii Bellows & Perring is a major pest of tomatoes, causing an irregular ripening disorder characterized externally by incomplete or inhibited reddening of fruit, especially in longitudinal sections, and internally by an increase in the amount of white tissue. Experiments were undertaken during the spring and fall of 1997 and 1998 and the spring of 1999 to develop an action threshold for applying the insect growth regulators (IGRs) buprofezin and pyriproxyfen to manage B. argentifolii and irregular ripening. The IGRs were applied when predetermined thresholds were reached and were compared with a high rate of the systemic insecticide imidacloprid, which was applied at transplanting and provided season-long whitefly control. Only plots treated when the numbers of sessile nymphs (second through fourth instars) reached five per 10 leaflets consistently had both external and internal irregular ripening severity ratings similar to the imidacloprid standard. Results were similar for buprofezin and pyriproxyfen even though the modes of action differ. The five nymphs per 10 leaflets threshold lends itself to field scouting because nymphal counts completed in the field using the unaided eye supplemented with a 10x hand lens were linearly and significantly related to counts completed in the laboratory with a dissecting microscope.