Nova Sco 2016 No. 2 = PNV J17225112-3158349 = ASASSN-16kd

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2016-09-01

AAVSO Alert Notice 550 announces the independent discovery of Nova Sco 2016 No. 2 = ASASSN-16kd = PNV J17225112-3158349 = V1656 Sco by Shigehisa Fujikawa (Kan'onji, Kagawa, Japan) at unfiltered CCD magnitude 11.6 on 2016 September 06.481 UT; and by ASAS-SN (Stanek et al., ATel #9469) at 12.13 V on 2016 September 06.00 UT. Spectroscopy indicating that Nova Sco 2016 No. 2 is a highly reddened classical Fe II-type nova was obtained by Arai and Honda (CBET 4320); by Bohlsen (ATel #9477); by Bersier et al. (ATel #9478); and by Prieto et al. (ATel #9479). Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

Nova Lupi 2011

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2011-08-01

Announcement of discovery of Nova Lupi 2011 = PNV J14542000-5505030. Discovered by Nicholas Brown (Quinns Rocks, Western Australia) on 2011 Aug. 4.73 UT at unfiltered mag=10.2 (tmax 400 film). Posted on the IAU Central Bureau for Astronomical Telegrams Transient Object Confirmation Page (TOCP) as PNV J14542000-5505030. Spectra obtained by Fred Walter (SUNY Stony Brook) 2011 August 9.0132 UT with the SMARTS 1.5m RC spectrograph at Cerro Tololo and reported in ATEL #3536 confirms that the object is an Fe II nova near maximum. Initially announced in [vsnet-alert 13560] (Nicholas Brown) and in AAVSO Special Notice #247 (Arne Henden). 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 and observations.

Nova Centauri 2013 = PNV J13544700-5909080

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2013-12-01

Announces the discovery of V1369 Cen = Nova Cen 2013 = PNV J13544700-5909080 by John Seach (Chatsworth Island, NSW, Australia) at unfiltered magnitude 5.5 on 2013 December 02.692 UT. Low-resolution spectra obtained by Locke on Dec. 03.3776 UT and by Kaufman on Dec. 03.621 UT show strong Ha and Hb emission lines, indicating the object is a nova. Announced on IAU CBAT Central Bureau Electronic Telegram 3732 (Daniel W. E. Green, ed.). Finder charts with sequences 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 and observations.

Eclipse of epsilon Aurigae

NASA Astrophysics Data System (ADS)

Templeton, Matthew R.

2009-07-01

The bright, long-period, eclipsing binary star epsilon Aurigae is predicted to begin its next eclipse late July or early August of 2009. Epsilon Aurigae is now past solar conjunction and has reappeared as a morning object. All observers -- both visual and instrumental -- are encouraged to contribute observations of the eclipse during the next two years, beginning immediately for morning observers. Observations are urgently requested right now because it is less likely to be observed in the morning, and the eclipse will begin within the next month. The AAVSO is participating in a global campaign to record this eclipse as part of the International Year of Astronomy 2009 celebrations, organized by the Citizen Sky project (http://www.citizensky.org). For experienced visual observers, please observe this star on a weekly basis, using charts available via VSP from the AAVSO website. For novice visual observers, we recommend participating in this observing program by following the Citizen Sky 10-Star tutorial program, which provides a simple training experience in variable star observing. Photoelectric observers belonging to the AAVSO PEP-V program may submit data as usual via the WebObs feature of the AAVSO website Blue&Gold section. Photoelectric observers may also contribute reduced observations in all filters (including infrared J- and H-bands) directly to the AAVSO via WebObs. Observers using wide-field CCD and DSLR systems are also encouraged to participate; avoid saturating the star. For those with narrower-field systems (D < 2 degrees), we recommend taking a large number (10-100) of very short exposures and then stacking the resulting images. Observations should be submitted to the AAVSO International Database. Aaron Price is coordinating Citizen Sky for the AAVSO, and Dr. Robert Stencel and Jeffrey Hopkins are co-leading the precision photometry efforts.

Observations of TT Ari requested in support of MOST observations

NASA Astrophysics Data System (ADS)

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.

Observations of CI Cam needed to support spectroscopy

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2016-10-01

Kelly Gourdji and Marcella Wijngaarden (graduate students at the University of Amsterdam/Anton Pannekoek Institute for Astronomy) have requested AAVSO observers' assistance in providing optical photometry of CI Cam in support of their high-resolution spectroscopy from now through January 2017. They write: "...We are currently observing the variable star CI Cam (the B[e] optical counterpart of a HMXB system) with the HERMES spectrograph at the Mercator Telescope in La Palma. Having observed the star for three nights now, the object appears to be in outburst. In particular, H alpha was measured to be 80 times the continuum flux, and increasing between Oct. 9 and 12. This is similar to the previous outburst in 2004/5. Photometric data obtained during the 2004/5 outburst suggested an outburst duration of about 3 months and a peak brightness of 11.2 in the V band." More information is available in ATel #9634 (Wijngaarden et al.). Multiple snapshot observations per night in BVRI are requested beginning immediately and continuing through January 2017. Time series are not necessary unless requested later via an AAVSO Special Notice. Observations made using other filters will be useful as well as long as there are multiple observations in these bands. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

Utilizing the AAVSO's Variable Star Index (VSX) in Undergraduate Research Projects (Poster abstract)

NASA Astrophysics Data System (ADS)

Larsen, K.

2016-12-01

(Abstract only) Among the many important services that the American Association of Variable Star Observers (AAVSO) provides to the astronomical community is the Variable Star Index (VSX; https://www.aavso.org/vsx/). This online catalog of variable stars is the repository of data on over 334,000 variable stars, including information on spectral type, range of magnitude, period, and type of variable, among other properties. A number of these stars were identified as being variable through automated telescope surveys, such as ASAS (All Sky Automated Survey). The computer code of this survey classified newly discovered variables as best it could, but a significant number of false classifications have been noted. The reclassification of ASAS variables in the VSX data, as well as a closer look at variables identified as miscellaneous type in VSX, are two of many projects that can be undertaken by interested undergraduates. In doing so, students learn about the physical properties of various types of variable stars as well as statistical analysis and computer software, especially the vstar variable star data visualization and analysis tool that is available to the astronomical community free of charge on the AAVSO website (https://www.aavso.org/vstar-overview). Three such projects are described in this presentation, to identify BY Draconis variables misidentified as Cepheids or "miscellaneous", and SRD semiregular variables and ELL (rotating ellipsoidal) variables misidentified as "miscellaneous", in ASAS data and VSX.

Utilizing the AAVSO's Variable Star Index (VSX) In Undergraduate Research Projects

NASA Astrophysics Data System (ADS)

Larsen, Kristine

2016-01-01

Among the many important services that the American Association of Variable Star Observers (AAVSO) provides to the astronomical community is the Variable Star Index (VSX - https://www.aavso.org/vsx/). This online catalog of variable stars is the repository of data on over 334,000 variable stars, including information on spectral type, range of magnitude, period, and type of variable, among other properties. A number of these stars were identified as being variable through automated telescope surveys, such as ASAS (All Sky Automated Survey). The computer code of this survey classified newly discovered variables as best it could, but a significant number of false classifications have been noted. The reclassification of ASAS variables in the VSX data, as well as a closer look at variables identified as miscellaneous type in VSX, are two of many projects that can be undertaken by interested undergraduates. In doing so, students learn about the physical properties of various types of variable stars as well as statistical analysis and computer software, especially the VStar variable star data visualization and analysis tool that is available to the astronomical community free of charge on the AAVSO website (https://www.aavso.org/vstar-overview). Two such projects are described in this presentation, the first to identify BY Draconis variables erroneously classified as Cepheids in ASAS data, and the second to identify SRD semiregular variables misidentified as "miscellaneous" in VSX.

The AAVSO Photoelectric Photometry Program in its Scientific and Socio-Historic Context

NASA Astrophysics Data System (ADS)

Percy, John R.

2011-05-01

Photoelectric photometry began in the 1900s through the work of Guthnick, Stebbins, and others who constructed and used photometers based on the recently-discovered photoelectric effect. The mid 20th century saw a confluence of several areas of amateur interest: astronomy, telescope making, radio and electronics, and general interest in space. This is the time when AAVSO photoelectric photometry (PEP) began, with observers using mostly hand-built photometers on hand-built telescopes. The 1980s brought a revolution: affordable off-the-shelf solid-state photometers, and infrastructure such as the International Amateur-Professional Photoelectric Photometry (IAPPP) conferences, books, and journal. The AAVSO developed a formal PEP program in the early 1980s. Its emphasis was on long-term monitoring of pulsating red giants. It was competing, not always successfully, with programs such as active sun-like binaries (RS CVn stars) which offered "instant gratification" in the form of publicity and quick publications. Nevertheless, the AAVSO PEP program has, through careful organization, motivation, and feedback to observers, produced extensive scientific results. In this presentation, I shall describe, as examples, my own work, its scientific significance, its educational benefit to dozens of my students, and its satisfaction to the observers. To some extent, the AAVSO PEP program has been superceded by its CCD program, but there is still a useful place for ongoing PEP observations of thousands of variable stars. Reference: http://www.aavso.org/sites/default/files/newsletter/PEP/lastpepnl.pdf Acknowledgements: I thank NSERC Canada for research support, my students, and AAVSO staff and observers, especially Howard Landis.

Monitoring of V380 Oph requested in support of HST observations

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2012-08-01

On behalf of a large Hubble Space Telescope consortium of which they are members, Dr. Joseph Patterson (Columbia University, Center for Backyard Astrophysics) and Dr. Arne Henden (AAVSO) requested observations from the amateur astronomer community in support of upcoming HST observations of the novalike VY Scl-type cataclysmic variable V380 Oph. The HST observations will likely take place in September but nightly visual observations are needed beginning immediately and continuing through at least October 2012. The astronomers plan to observe V380 Oph while it is in its current low state. Observations beginning now are needed to determine the behavior of this system at minimum and to ensure that the system is not in its high state at the time of the HST observations. V380 Oph is very faint in its low state: magnitude 17 to 19 and perhaps even fainter. Nightly snapshot observations, not time series, are requested, as is whatever technique - adding frames, lengthening exposur! es, etc. - necessary to measure the magnitude. It is not known whether V380 Oph is relatively inactive at minimum or has flares of one to two magnitudes; it is this behavior that is essential to learn in order to safely execute the HST observations. 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. NOTE: This campaign was subsequently cancelled when it was learned V830 Oph was not truly in its low state. See AAVSO Alert Notice 468 for details.

IM Nor monitoring requested for HST COS observations

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2017-02-01

Dr. Ed Sion (Villanova University) and colleagues have requested AAVSO observers' assistance in monitoring the symbiotic-type recurrent nova IM Nor in support of observations with the Hubble Space Telescope Cosmic Origins Spectrograph scheduled for 2017 February 13 - 17 UT. These observations are part of a study on short orbital period recurrent novae as Supernovae Type Ia progenitors. It is essential to know 24 hours prior to the HST COS observations that IM Nor is not in outburst, in order to protect the instrumentation. Also, photometry is needed throughout the HST window to insure knowledge of the brightness of the system. Observers are asked to monitor IM Nor with nightly snapshot images (V preferred) from now through February 20, and to report their observations promptly. It will be especially important to know the brightness of IM Nor each night through February 17 UT. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

V5588 SGR = Nova Sagittarii 2011 No. 2 = Pnv J18102135-2305306

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2011-04-01

Announces the discovery of Nova Sgr 2011 No. 2 = V5588 SGR = PNV J18102135-2305306 by Koichi Nishiyama (Kurume, Japan) and Fujio Kabashima (Miyaki, Japan) on ~ 2011 March 27.832 UT at unfiltered CCD magnitude mag 11.7. Spectra obtained by A. Arai, M. Nagashima, T. Kajikawa, and C. Naka (Koyama Astronomical Observatory, Kyoto Sangyo University) on Mar. 28.725 UT suggest that the object is a classical nova reddened by interstellar matter. The object was designated PNV J18102135-2305306 when posted on the Central Bureau's Transient Objects Confirmation Page (TOCP) webpage. E. Kazarovets, on behalf of the GCVS team, reports that the name V5588 Sgr has been assigned to this nova. It was nitially announced in CBET 2679 (Daniel W. E. Green, ed.) and AAVSO Special Notice #237 (Waagen). Additional information published in IAU Circular 9203 (Green, ed.). 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 and observations.

Supernova 2011by in NGC 3972 = Psn J11554556+5519338

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2011-04-01

Announces discovery of SN 2011by = PSN J11554556+5519338 by Zhangwei Jin (Ningbo, Zhejiang, China) and Xing Gao (Urumqi, Xinjiang, China) on 2011 Apr. 26.8234 UT at magnitude ~14.2 (unfiltered CCD). Spectra obtained on 2011 Apr. 27.5 UT by T. Zhang and Z. Zhou (National Astronomical Observatories of China) and X. Wang (Tsinghua Center for Astrophysics, Tsinghua University) show SN 2011by to be a type-Ia supernova about 10 days before maximum. Initially announced in IAU CBAT Central Bureau Electronic Telegrams 2708 (Daniel W. E. Green, ed.). The object was designated PSN J11554556+5519338 when posted on the Central Bureau's Transient Objects Confirmation Page (TOCP) webpage. 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, observations, and links to images.

Request to monitor 0103+59 HT Cas, 0809-76 Z Cha, 1004-69 OY Car AND Request to monitor 2147+13 LS Peg AND Request to monitor 1743-12 V378 Ser (Nova Ser 2005)

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2005-06-01

AAVSO Alert Notice 317 has three topics. First: Drs. Christopher Mauche (Lawrence Livermore National Laboratory), Peter Wheatley (Univ. of Leicester), and Koji Mukai (NASA GSFC) have obtained time on XMM-Newton to observe HT Cas, Z Cha, or OY Car in outburst. AAVSO assistance is requested in monitoring these stars closely so we can inform them promptly when any of them go into outburst. Very prompt notification is essential, because the satellite requires 2-4 days to move to the target after the observations are triggered, and the superoutbursts of OY Car and Z Cha last only about 10 days, while the HT Cas outbursts last only a little more than 2 days. Second: Dr. Darren Baskill (Univ. of Leicester) has requested optical observations of LS Peg (currently suspected as being a DQ Her nova-like) to coincide with upcoming observations by XMM-Newton. Observations are requested from now until July 8, with time series 12 hours before and after, and also during the XMM observation. Use an Ic or V filter (Ic preferred), maximum time precision, S/N=100. Third: Dr. Alon Retter (Penn State Univ.) has requested AAVSO assistance in observing V378 Ser (Nova Serpentis 2005). Please monitor V378 Ser over the coming weeks as the nova fades and report your observations to the AAVSO. Both visual and CCD observations are encouraged. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

The American Association of Variable Star Observers: Serving the Research Community in 2010 and Beyond

NASA Astrophysics Data System (ADS)

Templeton, Matthew R.; Henden, A. A.; Davis, K.; Kinne, R.; Watson, C.; Saladyga, M.; Waagen, E.; Beck, S.; Menali, G.; Price, A.; Turner, R.

2010-05-01

The American Association of Variable Star Observers (AAVSO) holds the largest single online database of variable star data in the world, collected from thousands of amateur and professional observers during the past century. One of our core missions is to preserve and distribute these data to the research community in service to the science of variable star astronomy. But as an organization, the AAVSO is much more than a data archive. Our services to the research community include: monitoring for and announcement of major astronomical events like novae and supernovae; organization and management of observing campaigns; support for satellite and other TOO observing programs by the professional community; creation of comparison star sequences and generation of charts for the observer community; and observational and other support for the amateur, professional, and educator communities in all things related to variable stars. As we begin a new century of variable star astronomy we invite you to take advantage of the services the AAVSO can provide, and to become a part of our organization yourselves. In this poster, we highlight some of the most important services the AAVSO can provide to the professional research community, as well as suggest ways in which your research may be enhanced with support from the AAVSO.

Request to monitor 2035-01 AE Aqr for multiwavelength campaign AND Reminder to monitor HT Cas, Z Cha, and OY Car

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2005-08-01

AAVSO Alert Notice 326 contains two topics. First: Dr. Christopher Mauche (Lawrence Livermore National Laboratory) has requested our assistance in monitoring the novalike intermediate polar AE Aqr in support of multiwavelength (gamma-ray, X-ray, UV, optical, and radio) observations scheduled for August-September 2005. AAVSO observations, particularly CCD ones, are requested to correlate with these multiwavelength observations; visual observations are also encouraged. Second: as announced in Alert Notice 317, Drs. Christopher Mauche, Peter Wheatley, and Koji Mukai have obtained time on XMM-Newton to observe HT Cas, Z Cha, or OY Car in outburst, and they have requested our assistance in monitoring these stars closely so we can inform them promptly when any of them go into outburst. Very prompt notification is essential because of the time required to trigger the satellite and the shortness of the outbursts of the target stars. Please monitor HT Cas, OY Car, and Z Cha closely from now through at least a month after the last observing window closes, and notify Headquarters immediately if any of the target stars goes into outburst. Both visual and CCD observations are encouraged. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

Observations of V420 Aur (HD 34921) needed to support spectroscopy

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2016-10-01

Marcella Wijngaarden and Kelly Gourdji (graduate students at the University of Amsterdam/Anton Pannekoek Institute for Astronomy) have requested AAVSO observers' assistance in providing optical photometry of V420 Aur in support of their high-resolution spectroscopy with the Mercator telescope + Hermes spectrograph in La Palma 2016 October 7 through 17. They write: "[V420 Aur (HD 34921) is] the optical Be star that is part of a peculiar High Mass X-ray Binary...[that exhibits highly] complex and variable spectra...it is difficult to construct a physical model of this HMXB system, though based on these observations, the system is thought to contain a B[e] star with a dense plasma region, an accretion disk around a neutron star, a shell and circumstellar regions of cold dust. It has been over a decade since the last spectra were taken, and, given the highly variable nature of this star, we expect new observations to yield new information that will contribute to a better understanding of this system." Observations in BVRI (preferred over other bands) are requested beginning immediately and continuing through October 24. In all cases, timeseries in a few bands (i.e. BVRI) are preferred over single/a few observations in the other bands as it is the variability on relatively short timescales that is most important. "The target is bright so exposures should be long enough to reach good signal to noise in order to see the small variability amplitude but without saturating the target/comparison stars. We will study the variability on several timescales, so observations starting from a few per night to high cadence timeseries are useful." Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

Very rare outburst of the symbiotic variable AG Peg

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2015-06-01

The symbiotic variable AG Peg is in outburst, the first one observed since its only known outburst, which occurred in 1860-1870. Currently at visual/V magnitude 7.2 (B=7.8), it is an excellent target for visual, PEP, CCD, and DSLR observers and spectroscopists. The current outburst began after 2015 May 27 UT (T. Markham, Leek, Staffordshire, England, from the BAAVSS online database) and was underway by June 13.90 (A. Kosa-Kiss, Salonta, Romania). AG Peg has a very interesting history. Regarding the 1860-1870 outburst, data collected by E. Zinner (Merrill, 1959, S&T, 18, 9, 490) show AG Peg slowly brightening from visual magnitude 9.2 in 1821 to 8.0 in 1855, then at 6.2 in 1860 and brightening to 6.0 in 1870, then in decline at 6.8 by 1903, and continuing to decline slowly ( 6.9 in 1907, 8.0 in 1920, 8.3 in 1940). Observations in the AAVSO International Database since July 1941 show that the decline has continued without interruption from an average magnitude of 7.7 to an average magnitude of 8.8-9.0 by mid-January 2015. The AAVSO data since 1941 also show the periodic 0.4-magnitude variations ( 825 days) that have been present since the 1920s. Thus, after taking about 10 years to brighten from its minimum magnitude of about 9 to its maximum magnitude of 6.0, and then fading gradually over 140-145 years, AG Peg is now in outburst again. There are no observations of the 1860-1870 outburst that show the outburst's beginning. This time, however, in 2015, the opportunity is here to follow the outburst itself closely and learn just what this system does during outburst. Observations in all bands and visual observations are strongly encouraged. AG Peg is bright enough to be a very good PEP target. For spectroscopists, AG Peg has an extremely complex spectrum that undergoes substantial changes and would make a very interesting target. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. Precise observing instructions and other details are given in the full Alert Notice.

Nova Sagittarii 2014 = PNV J18250860-2236024 AND Erratum

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2014-02-01

Details of discovery of Nova Sagittarii 2014 (PNV J18250860-2236024) and procedures for observing and reporting observations are announced. Discovered by Sigeru Furuyama (Tone-machi, Ibaraki-ken, Japan) andreported by S. Nakano (Sumoto, Japan) at unfiltered CCD magnitude 8.7 on 2014 Jan. 26.857 UT. Coordinates: R.A. 18 25 08.60 Decl. = -22 36 02.4 (2000.0). Nova Sgr 2014 is Fe II-type classical nova past maximum, per low-resolution spectra obtained by A. Arai on 2014 Jan. 30.87 UT. Announced in IAU CBAT CBET 3802 (D. W. E. Green, ed.). 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 and observations. Also, an Erratum is reported. In AAVSO Alert Notice 496, Mati Morel (MMAT, Thornton, NSW, Australia) was credited with the discovery of the 1989 outburst of V745 Sco. The discoverer was William Liller (LIW, Vina del Mar, Chile), who observed V745 Sco on 1989 July 30.08 UT at magnitude 9.7 (PROBLICOM discovery using 2415 film with orange filter).

CI Aql monitoring needed to support HST observations

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2016-10-01

Dr. Edward Sion (Villanova University) has requested AAVSO observers' assistance in monitoring the recurrent nova CI Aql in support of observations with the Hubble Space Telescope Cosmic Origins Spectrograph scheduled for October 31 - November 2, 2016, and November 3 - November 5, 2016. These observations are part of a study on short orbital period recurrent novae as Supernovae Type Ia progenitors. It is essential to know 24 hours prior to the HST COS observations that CI Aql is not in outburst, in order to protect the instrumentation. Observers are asked to keep an eye on CI Aql with nightly snapshot images (V preferred) from now until November 12, and to report their observations promptly. It will be especially important to know the brightness of CI Aql each night for October 28 through November 7 UT. Visual observations are welcome. CI Aql (Nova Aql 1917) has had recurrent outbursts in 1941 and 2000, brightening to V 8.5. At minimum it is V 16-16.5 or fainter. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

Supernova 2011fe in M101 (NGC 5457) = PSN J14030581+5416254

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2011-08-01

The discovery is reported of Supernova 2011fe in NGC 5457 = PSN J14030581+5416254 by the Type Ia supernova science working group of the Palomar Transient Factory, Peter Nugent et al., on 2011 Aug. 24 UT at magnitude 17.2 (g-band, calibrated with respect to the USNO catalog. (Credit for an independent discovery by Mathew Marulla and Tavi Grenier was later rescinded by D. Green, Gentral Bureau for Astronomical Telegrams.) A spectrum obtained on 2011 Aug. 24 UT indicates that SN 2011fe is probably a Type Ia supernova at a very early phase. SN 2011fe was initially announced in ATEL #3581 (Peter Nugent et al.), AAVSO Special Notice #250 (Matthew Templeton), and Central Bureau for Astronomical Telegrams (CBAT) Electronic Telegram 2792 (Daniel W. E. Green, ed.). According to Green, the object was designated PSN J14030581+5416254 when posted on the CBAT Transient Objects Confirmation Page (TOCP) webpage. 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, observations, and links to images.

Nova Sco 2011 No. 2 = PNV J16364440-4132340 = PNV J16364300-4132460

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2011-09-01

Announcement of discovery of Nova Sco 2011 No. 2 = PNV J16364440-4132340 = PNV J16364300-4132460. Discovered independently by John Seach (Chatsworth Island, NSW, Australia, on 2011 Sep. 06.37 UT at mag=9.8 (DSLR)) and by Yuji Nakamura (Kameyama, Mie, Japan, on 2011 Sep. 06.4313 UT at mag=9.7 C (CCD)). Posted on the IAU Central Bureau for Astronomical Telegrams Transient Object Confirmation Page (TOCP) as PNV J16364440-4132340 (Nakamura) and PNV J16364300-4132460 (Seach); identifications consolidated in VSX under PNV J16364440-4132340. Spectra obtained by A. Arai et al. on 2011 Sep. 7.42 UT suggest a highly reddened Fe II-type classical nova. Spectra by F. Walter and J. Seron obtained Sep. 2011 8.091 UT confirm a young galactic nova; they report spectra are reminiscent of an early recurrent nova. Initially announced in AAVSO Special Notice #251 (Matthew Templeton) and IAU Central Bureau Electronic Telegram 2813 (Daniel W. E. Green, ed.). 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 and observations.

Digitizing Olin Eggen's Card Database

NASA Astrophysics Data System (ADS)

Crast, J.; Silvis, G.

2017-06-01

The goal of the Eggen Card Database Project is to recover as many of the photometric observations from Olin Eggen's Card Database as possible and preserve these observations, in digital forms that are accessible by anyone. Any observations of interest to the AAVSO will be added to the AAVSO International Database (AID). Given to the AAVSO on long-term loan by the Cerro Tololo Inter-American Observatory, the database is a collection of over 78,000 index cards holding all Eggen's observations made between 1960 and 1990. The cards were electronically scanned and the resulting 108,000 card images have been published as a series of 2,216 PDF files, which are available from the AAVSO web site. The same images are also stored in an AAVSO online database where they are indexed by star name and card content. These images can be viewed using the eggen card portal online tool. Eggen made observations using filter bands from five different photometric systems. He documented these observations using 15 different data recording formats. Each format represents a combination of filter magnitudes and color indexes. These observations are being transcribed onto spreadsheets, from which observations of value to the AAVSO are added to the AID. A total of 506 U, B, V, R, and I observations were added to the AID for the variable stars S Car and l Car. We would like the reader to search through the card database using the eggen card portal for stars of particular interest. If such stars are found and retrieval of the observations is desired, e-mail the authors, and we will be happy to help retrieve those data for the reader.

FO Aqr time-series observations requested

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2016-07-01

Dr. Colin Littlefield (University of Notre Dame) and colleagues Drs. Peter Garnavich (Notre Dame), Erin Aadland (Minnesota State), and Mark Kennedy (University College Cork) have requested AAVSO assistance in monitoring the intermediate polar cataclysmic variable FO Aqr beginning immediately. Littlefield, who with his colleagues recently published ATel #9216 and #9225, writes: "This system is in a faint state for the first time in its observational record, implying a dropoff in the mass-transfer rate. AAVSO observations contributed by Shawn Dvorak [the only observer following FO Aqr at the time] were particularly helpful in detecting this low state. Since early May, the system has recovered to V 15, but it is still well below its normal brightness. In addition, our time-series photometry shows a very strong 11.26-minute photometric period. By contrast, during its bright state, FO Aqr's light curve is dominated by a 20.9-minute period, corresponding with the spin period of the white dwarf. We interpret our observations as evidence that the system's accretion processes have changed dramatically as a result of the reduced mass-transfer rate. We have...determined that...[the 11.26-min] periodicity is dependent on the orbital phase of the binary. The 11.26-min period is dominant for about half of the orbit, but for the other half, a 22.5-min period is stronger. AAVSO observers can help us study both of these periods as well as their dependence on the orbital phase. We are particularly interested in any changes in this behavior as the system continues to brighten...Time-series photometry of FO Aqr [is requested] in order to better study the evolution of the 11.26-minute period as the system rebrightens. Unfiltered photometry reduced with a V zeropoint would be the most useful to us...A cadence of less than 60 seconds per image is important, given the brevity of these periods (especially the 11.26-min period). Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

SN 2017eaw in NGC 6946 (PSN J20344424+6011359)

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2017-05-01

AAVSO Alert Notice 577 announces and reports on the discovery of SN 2017eaw (PSN J20344424+6011359) in NGC 6946 by Patrick Wiggins (Tooele, UT) at unfiltered CCD magnitude 12.8 on 2017 May 14.2383 UT. Spectra indicating the object is a pre-maximum Type II supernova was reported by Y.-C. Cheng et al. (ATel #10374), by D. Xiang et al. (ATel #10376), and by L. Tomasella et al. on behalf of the NUTS collaboration (ATel #10377). Information on the probable progenitor red supergiant was given by R. Khan (ATel #10373), and by S. Van Dyk et al., who,using HST ACS/WFC archival data, reported the probable progenitor to be a red supergiant located approximately 6.4 WFC pixels (about 0.3 arcsec) to the southwest of the discovery position (ATel #10378). A. Kong and K. Li reported that Chandra archival X-ray data (2001-2012) show no X-ray emission correlated with the supernova position; Swift TOO observations from May 14 (two observations 8 hours apart) show X-ray emission present and increasing (ATel #10380). Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

Twenty Years of Work with Janet Mattei on Cataclysmic Variables

NASA Astrophysics Data System (ADS)

Szkody, P.

2005-08-01

Janet Mattei and the AAVSO database have had a large impact on the field of cataclysmic variables, especially in the areas of outburst light curves of dwarf novae and ground-based support of space observations. A summary of some of the major results from AAVSO data during the last 20 years is presented.

NR TrA (Nova TrA 2008) monitoring in support of XMM observations

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2017-03-01

Dr. Fred Walter (Stony Brook University) has requested AAVSO observers' assistance in monitoring NR TrA (Nova TrA 2008) in support of upcoming XMM Newton observations. The XMM observations will take place 2017 March 13 06:21 through March 14 10:34 UT. Walter writes: "NR TrA (Nova TrA 2008) is a compact eclipsing system with a 5.5 hour period. It was a normal Fe II nova that, upon reaching quiescence, took on the appearance of a super-soft source in the optical high state, which suggests an extremely high mass accretion rate. The optical spectrum is dominated by hot permitted lines of O VI, N V, C IV, and He II. Some nova-like variables have similar spectra, though generally without the hot emission lines. Primary eclipse is broad - nearly 40% of the orbit - and deeper at shorter wavelengths, which suggests the eclipse of a hot accretion disk. Primary eclipse depth is about 1 mag at V. There appears to be a shallow secondary eclipse.The primary aim [of the XMM observations] is to detect and characterize the eclipse at X-ray and UV wavelengths. We will obtain low cadence BVRI/JHK observations with SMARTS/Andicam. We request AAVSO support to obtain continuous photometric time series simultaneous with the XMM observation. Any filters are acceptable, but standard Johnson B, V or Cousins R, I are preferred. Clear filters are acceptable. Time resolution better than 5 minutes and uncertainties (outside of eclipse) <0.02 mag are preferred. The best ephemeris I have is: minimum light at JD 55956.822 + 0.219109E. This is based on data from 2013-2015." Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

Observations of the eclipsing binary b Persei

NASA Astrophysics Data System (ADS)

Templeton, Matthew R.

2015-01-01

Dr. Robert Zavala (USNO-Flagstaff) et al. request V time-series observations of the bright variable star b Persei 7-21 January 2015 UT, in hopes of catching a predicted eclipse on January 15. This is a follow-up to the February 2013 campaign announced in Alert Notice 476, and will be used as a photometric comparison for upcoming interferometric observations with the Navy Precision Optical Interferometer (NPOI) in Arizona. b Per (V=4.598, B-V=0.054) is ideal for photoelectric photometers or DSLR cameras. Telescopic CCD observers may observe by stopping down larger apertures. Comparison and check stars assigned by PI: Comp: SAO 24412, V=4.285, B-V = -0.013; Check: SAO 24512, V=5.19, B-V = -0.05. From the PI: "[W]e wanted to try and involve AAVSO observers in a follow up to our successful detection of the b Persei eclipse of Feb 2013, AAVSO Alert Notice 476 and Special Notice 333. Our goal now is to get good time resolution photometry as the third star passes in front of the close ellipsoidal binary. The potential for multiple eclipses exists. The close binary has a 1.5 day orbital period, and the eclipsing C component requires about 4 days to pass across the close binary pair. The primary eclipse depth is 0.15 magnitude. Photometry to 0.02 or 0.03 mags would be fine to detect this eclipse. Eclipse prediction date (JD 2457033.79 = 2015 01 11 UT, ~+/- 1 day) is based on one orbital period from the 2013 eclipse." More information is available at PI's b Persei eclipse web page: http://inside.warren-wilson.edu/~dcollins/bPersei/. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details and information on the targets.

AAVSO Target Tool: A Web-Based Service for Tracking Variable Star Observations (Abstract)

NASA Astrophysics Data System (ADS)

Burger, D.; Stassun, K. G.; Barnes, C.; Kafka, S.; Beck, S.; Li, K.

2018-06-01

(Abstract only) The AAVSO Target Tool is a web-based interface for bringing stars in need of observation to the attention of AAVSOís network of amateur and professional astronomers. The site currently tracks over 700 targets of interest, collecting data from them on a regular basis from AAVSOís servers and sorting them based on priority. While the target tool does not require a login, users can obtain visibility times for each target by signing up and entering a telescope location. Other key features of the site include filtering by AAVSO observing section, sorting by different variable types, formatting the data for printing, and exporting the data to a CSV file. The AAVSO Target Tool builds upon seven years of experience developing web applications for astronomical data analysis, most notably on Filtergraph (Burger, D., et al. 2013, Astronomical Data Analysis Software and Systems XXII, Astronomical Society of the Pacific, San Francisco, 399), and is built using the web2py web framework based on the python programming language. The target tool is available at http://filtergraph.com/aavso.

Request for Observations of V405 Peg

NASA Astrophysics Data System (ADS)

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.

Beta Pic observations requested for BRITE-Constellation

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2017-01-01

The AAVSO is part of the BRITE-Constellation Ground Based Observations Team (GBOT), supporting cutting-edge science from the BRITE-Constellation satellites and coordinating with BRITE-Constellation scientist Dr. Konstanze Zwintz (Universitaet Innsbruck) and her team. The delta Scuti star beta Pic (NSV 16683) (3.80-3.86V) is one of the BRITE stars being focused on during this season. Bet Pic is particularly interesting now because a transit of the star's planet's Hill sphere (the region around a planet in which it dominates the attraction of satellites) is predicted to occur during 2017-2018. Ongoing observations beginning now are valuable to establish a baseline prior to the transit. The AAVSO's webpage on the BRITE target stars was updated in November with information on bet Pic from Dr. Zwintz. AAVSO observers with appropriate equipment and located at a southern enough latitude are encouraged to observe bet Pic. Its brightness makes bet Pic well suited to PEP and DSLR photometry; CCD photometry is also possible. However, great care must be taken by all observers, especially those using CCD, to avoid saturation. As the amplitude of this star is very small, visual observations are very difficult, but they are welcome. Multicolor (BVR) photometry better than 0.01 magnitude and time-series observations with a cadence of a few minutes (less than 10 minutes) are requested beginning now and continuing at least through 2017 and likely through 2018. The precision and cadence required are essential in order for the data to be most useful for studying the transit. Spectroscopists wishing to participate should submit their spectra directly to Dr. Konstanze Zwintz (konstanze.zwintz@uibk.ac.at). Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

Period Changes in Pulsating Red Supergiant Stars: A Science and Education Project

NASA Astrophysics Data System (ADS)

Percy, J. R.; Favaro, E.; Glasheen, J.; Ho, B.; Sato, H.

2008-12-01

We describe research done as part of the University of Toronto Mentorship Program, which enables outstanding senior high school students to work on research projects at the university. The students began with extensive background reading on variable stars, and became familiar with various forms of time-series analysis by applying them to a few red supergiant variables in the AAVSO International Database; we report on the results. They also prepared a useful manual for our publicly-available self-correlation analysis software. They undertook an intensive analysis of the period changes in BC Cyg, using the AAVSO and Turner data and the (O-C) method, in the hope that evolutionary period changes could be observed. The (O-C) diagram, however, is dominated by errors in determining the times of maximum, and by the effects of cycle-to-cycle period fluctuations. As a result, the (O-C) method is generally not effective for these stars. We also describe the Mentorship Program and its elements, and reflect on the students' experience.

Southern Clusters for Standardizing CCD Photometry

NASA Astrophysics Data System (ADS)

Moon, T. T.

2017-06-01

Standardizing photometric measurements typically involves undertaking all-sky photometry. This can be laborious and time-consuming and, for CCD photometry, particularly challenging. Transforming photometry to a standard system is, however, a crucial step when routinely measuring variable stars, as it allows photoelectric measurements from different observers to be combined. For observers in the northern hemisphere, standardized UBVRI values of stars in open clusters such as M67 and NGC 7790 have been established, greatly facilitating quick and accurate transformation of CCD measurements. Recently the AAVSO added the cluster NGC 3532 for southern hemisphere observers to similarly standardize their photometry. The availability of NGC 3532 standards was announced on the AAVSO Variable Star Observing, Photometry forum on 27 October 2016. Published photometry, along with some new measurements by the author, provide a means of checking these NGC 3532 standards which were determined through the AAVSO's Bright Star Monitor (BSM) program (see: https://www.aavso.org/aavsonet-epoch-photometry-database). New measurements of selected stars in the open clusters M25 and NGC 6067 are also included.

Digital Archiving: Where the Past Lives Again

NASA Astrophysics Data System (ADS)

Paxson, K. B.

2012-06-01

The process of digital archiving for variable star data by manual entry with an Excel spreadsheet is described. Excel-based tools including a Step Magnitude Calculator and a Julian Date Calculator for variable star observations where magnitudes and Julian dates have not been reduced are presented. Variable star data in the literature and the AAVSO International Database prior to 1911 are presented and reviewed, with recent archiving work being highlighted. Digitization using optical character recognition software conversion is also demonstrated, with editing and formatting suggestions for the OCR-converted text.

Monitoring of Northern dwarf novae for radio jets campaign

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2014-10-01

Ms. Deanne Coppejans (PhD candidate, Radboud University Nijmegen (Netherlands) and University of Cape Town) and colleagues have requested AAVSO observer assistance in monitoring nine Northern dwarf novae in support of their campaign to observe them in outburst with the Very Large Array (VLA) to search for radio jets. They will observe 5 targets from the following list: U Gem*, EX Dra, Z Cam*, RX And*, EM Cyg, AB Dra, SY Cnc, SU UMa*, and YZ Cnc*. Stars with an asterisk (*) will be given higher priority. The campaign will begin now, starting with monitoring of RX And and EM Cyg, and run through September 2015, or until all five VLA triggers have been used. This campaign is similar to previous AAVSO campaigns, namely the 2007 campaign to monitor a sample of 10 dwarf novae (AAVSO Alert Notice 345), which resulted in the first detection of a radio jet in a dwarf nova system (Koerding et al. 2008, Science, 320, 1318), and the ones carried out at the request of Dr. James Miller-Jones and colleagues on SS Cyg in 2010-2011 (AAVSO Special Notices #204, #206, Alert Notice 445). The latter resulted in an accurate distance determination to SS Cyg, thereby reconciling its behavior with our understanding of accretion disc theory in accreting compact objects (Miller-Jones et al. 2013, Science, 340, 950). Ms. Coppejans writes: "The relation between accretion and outflow is one of the basic problems in modern astrophysics. It has long been thought that CVs are the only accreting systems that do not produce jets, and this notion has even been used to constrain jet models. However, there are now some indications that CVs do show jets, possibly allowing a universal link between accretion and ejection. Radio observations provide the best unambiguous tracer of the corresponding jet or directed outflow, but there are only two clear detections. By observing a more extensive sample of cataclysmic variables in outburst we will determine the existence of jets or other outflows in these accreting binary systems. These observations will decide if either CVs do show jets and thus support a universal link between accretion and ejection, or if they do not show jets, further constraining future jet models." The radio jet, if it exists in any of these nine systems, is expected to be seen shortly after the beginning of the outburst (as it was in SS Cyg). Catching the outburst as it is just starting and reporting that information to AAVSO HQ immediately is crucial, as the astronomers need to be alerted, make their decision whether to trigger the VLA observations, and allow enough time for the VLA to start the observations. Please observe these systems NIGHTLY (visual, CCD V) and report all observations as soon as is practical. In the event of an outburst, please report your observations as quickly as you can via WebObs, and also notify Dr. Matthew Templeton and Elizabeth Waagen at AAVSO Headquarters and Deanne Coppejans. 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 and information on the targets.

Outburst of the recurrent nova V745 Sco

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2014-02-01

The outburst of the recurrent nova V745 Sco (Nova Sco 1937) by Rod Stubbings (Tetoora Road, VIC, Australia) at visual magnitude 9.0 on 2014 February 6.694 UT is reported. This recurrent nova is fading quickly. Follow-up observations of all types (visual, CCD, DSLR) are strongly encouraged, as is spectroscopy; fast time-series of this nova may be useful to detect possible flaring activity as was observed during the outburst of U Scorpii in 2010. Coincident time-series by multiple observers would be most useful for such a study, with a V-filter being preferred. Observations reported to the AAVSO International Database show V745 Sco at visual mag. 10.2 on 2014 Feb. 07.85833 UT (A. Pearce, Nedlands, W. Australia). 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. Previous outbursts occurred in 1937 and 1989. The 1937 outburst was detected in 1958 (in decline at magnitude 11.0 on 1937 May 11.1 UT; outburst had occurred within the previous 19 days) by Lukas Plaut on plates taken by Hendrik van Gent at the Leiden Observatory; the object was announced as Nova Sco 1937 and later assigned the GCVS name V745 Sco. The 1989 outburst was detected on 1989 August 1.55 UT by Mati Morel (MMAT, Thornton, NSW, Australia) at visual magnitude 10.4 and in decline. Dr. Bradley Schaefer (Louisiana State University) reports (2010ApJS..187..275S) in his comprehensive analysis of the 10 known galactic recurrent novae (including V745 Sco) that the median interval between recurrent novae outbursts is 24 years. The interval since the 1989 outburst of V745 Sco is 24.10 years. See the Alert Notice for additional visual and multicolor photometry and for more details.

Miras and Janet Mattei

NASA Astrophysics Data System (ADS)

Willson, L. A.

2005-08-01

Janet Mattei appears among the authors on over 70 papers concerning Mira variables or related classes of red variables. She contributed to the planning or execution of some of the research in this area, but more often appeared as representative for the thousands of AAVSO observers world wide. Janet also helped to start several observational programs concerning particular types of variables, and was involved with the planning and/or data analysis on space missions that observed these stars. In this review I put her contributions, and the AAVSO's contributions while she was Director, into a general context of work in this field.

Monitoring of CH Cyg requested for Chandra and HST observations

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2012-03-01

Dr. Margarita Karovska, Harvard-Smithsonian Center for Astrophysics, has requested visual and photometric observations of the symbiotic variable CH Cyg in preparation for and support of Chandra and HST observations scheduled for later in March 2012. Dr. Karovska's observations will be a followup investigation of the central region of CH Cyg and its jet that was discovered a couple of years ago. AAVSO observations are requested in order to monitor the state of the system and correlate with the satellite observations. Visual observations and CCD/PEP observations in all bands - U through J and H - are requested. Daily observations now through April 2012 and high-speed photometry through March would be appreciated. CH Cyg is currently at visual magnitude 7.7. Halpha, OIII region, and optical spectroscopy are also requested. More details on the exact dates and times of the satellite observations will be announced when they become available, but daily monitoring should begin now. [HST observations scheduled for 2012 March 18; Chandra delayed some days due to X-class solar flare of 2012 March 7.] Coordinates: RA 19 24 33.07 Dec. +50 14 29.1 (J2000.0). Finder charts may be created and data from the AAVSO International Database may be viewed, plotted, or downloaded (www.aavso.org).

Supernova 2011at = PSN J09285756-1448206 in MCG -02-24-27

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2011-03-01

Announces the discovery of SN 2011at = PSN J09285756-1448206 in MCG -02-24-27 by Lou Cox, Jack Newton, and Tim Puckett (Ellijay, GA, in the course of the Puckett Observatory Supernova Search) on 2011 March 10.214 UT at unfiltered CCD magnitude 14.5. Spectra obtained March 11.81 UT with the Swift satellite (+UVOT) by F. Bufano (Istituto Nazionale di Astrofisica (INAF), Osservatorio Astronomico di Catania), S. Benetti (INAF, Osservatorio Astronomico di Padova), and A. Pastorello (Queen's University, Belfast, et al.); and on March 12 UT with the F. L. Whipple Observatory 1.5-m telescope (+FAST) by M. Calkins (reported by G. H. Marion, Harvard-Smithsonian Center for Astrophysics (CfA), on behalf of the CfA Supernova Group) show SN 2011at to be a type-Ia supernova a few days before/around maximum. The object was designated PSN J09285756-1448206 when posted on the Central Bureau's Transient Objects Confirmation Page (TOCP) webpage. Initially announced in CBET 2676 (Daniel W. ! E. Green, ed.). 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.

Anne S. Young: Professor and Variable Star Observer Extraordinaire

NASA Astrophysics Data System (ADS)

Bracher, Katherine

2011-05-01

Anne Sewell Young (1871-1961) was one of the eight original members of the AAVSO, to which she contributed more than 6500 observations over 33 years. She also taught astronomy for 37 years at Mount Holyoke College; among her students was Helen Sawyer Hogg. This paper will look at her life and career both at Mount Holyoke and with the AAVSO.

Monitoring of EPIC 204278916 requested

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2017-04-01

Dr. Carlo Manara (ESA Science and Technology SCI-S, the Netherlands) and colleagues have requested AAVSO assistance in monitoring the young, disk-bearing low-mass (M type) pre-main-sequence star EPIC 204278916 (2MASS J16020757-2257467). Dr. Manara reports that this star showed "a very interesting dimming event in August-September 2014 which may be caused by transiting material (exo-comets like) (Scaringi et al., 2016MNRAS.463.2265S, https://ui.adsabs.harvard.edu/#abs/2016MNRAS.tmp.1267S/abstract). It would be very useful to know whether this event has any periodicity in order to constrain the possible scenario...The major dimming [up to 65%] we see is 1.2 mag in V, others are 0.5-0.8 mag" in V. He also notes that "the dimming event we saw lasted for some 25 days, although the most extreme event was 1 day long. Based on the noisy WASP data we have [there are] some suggestions that the event happens every 100 days, but we are not sure about it." Manara requests ongoing monitoring of this system to look for additional dimming events and to observe any that are seen, so that he and his colleagues may determine if periodicity exists in these events and to study its nature. Beginning now and continuing until further notice, nightly observations in V are requested. Weekly observations in B are also requested. If a dimming event occurs, observations in V and B at a higher cadence are requested. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

AR Sco observing campaign

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2016-08-01

Dr. Thomas Marsh (University of Warwick) and colleagues have requested AAVSO coverage of the intriguing binary AR Sco in support of upcoming Newton-XMM observations scheduled for 2016 September 10 15:41 - September 11 02:26 UT. This fascinating binary system is the subject of an exciting paper in the July 2016 issue of Nature (Marsh et al., 2016Natur.537..374M; pre-print version at arXiv (http://arxiv.org/abs/1607.08265). Marsh writes of their research on AR Sco: "...it was down to [the amateurs [who are co-authors] on the paper that we got onto it in the first place. Coverage immediately before, after and (especially) during [the XMM observations] would be great. The most challenging aspect is the time resolution: ideally one wants a cadence < 29 seconds because of the strong harmonic of the basic 2 minute period, and the faster the better. Observers should use whatever filter (including clear/white light) is needed to allow them to match this constraint. Accurate timing is also essential - the centres of the exposures need to be known to better than ± 2 seconds, and preferably better." A page of materials on AR Sco related to the Nature paper may be found at http://deneb.astro.warwick.ac.uk/phsaap/arsco-info/ . Item #9 on that page is a YouTube video of a fascinating movie Dr. Marsh made of AR Sco from their data (https://www.youtube.com/watch?v=QJGAv2jCF4s&feature=youtu.be). Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

Engaging Generation Now, Inspiring Generation Next

NASA Astrophysics Data System (ADS)

Simonsen, Mike; Gay, P.

2008-05-01

In 2008, the Education and Public Outreach Committee of the American Association of Variable Star Observers (AAVSO) initiated several new strategies for disseminating accurate, stimulating, engaging information on general astronomy and variable star science to thousands of students, parents, and amateur astronomers each year through astronomy clubs, societies, and star party events. We are initiating contact with astronomy clubs and organizations to offer qualified speakers from the AAVSO Speakers Bureau for their meetings and activities. The current roster of speakers include, professional astronomers, doctors, engineers, teachers and some of the world's leading variable star observers. Request information is available on the AAVSO website. For organizations and individuals unable to engage one of our speakers due to time, distance or financial constraints, we have made PowerPoint presentations used in previous talks available free for download from the same web pages. Thousands of amateur astronomers and their children attend star parties each year. As an extension of our speakers’ bureau, our goal is to have an AAVSO representative at each of the major star parties each year giving an enthusiastic talk on variable stars or related astronomical subject and supplying inspirational printed materials on astronomy and amateur contributions to science. The nation's largest astronomy clubs have monthly newsletters they distribute to their membership. Newsletter editors are constantly in need of quality, interesting content to fill out their issues each month. We are offering a `writers’ bureau’ service to newsletter editors, similar to the news wire services used by newspapers. We will supply up to a half dozen articles on astronomy and variable star science each month for editors to use at their discretion in their publications. Our goal is to provide information, inspiration and encourage participation among amateur astronomers and their kids, our next generation of astronomers.

An Overview of the Swinburne Online Astronomy Courses

NASA Astrophysics Data System (ADS)

Dempsey, F.

2013-06-01

(Abstract only) An overview of the online astronomy courses at Swinburne University of Technology is presented for the benefit of AAVSO members who might be interested in the courses or programs. The decision to take the online Master's degree in astronomy at Swinburne was a natural evolution from being interested in astronomy at an early age, being an amateur astronomer all my life, and being a variable star observer and member of the AAVSO for the past several decades. This presentation provides an overview of the program and examples of the course materials, assignments, and projects that may provide some idea of the commitment and expectations for AAVSO members considering the program.

Monitoring of Swift J1357.2-0933 (CRTS J135716.8-093238) requested

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2017-04-01

Dr. Gregory Sivakoff (University of Alberta) has requested AAVSO observers' assistance in monitoring the black hole X-ray binary Swift J1357.2-0933 (CRTS J135716.8-093238) during its current outburst. Sivakoff writes: "...[Because it] is at high Galactic latitude...extinction is relatively small and the bright blue nature of the outburst can be observed readily by citizen astronomers as the source fades into quiescence on a timescale of a few months. AAVSO observations will be critical in complementing multiple multi-wavelength campaigns observing this outburst...In addition, this source is known to undergo recurring rapid dips. These dips can last for 10s of seconds, and recur on timescales of a few minutes. This is a great source for AAVSO observers, particularly CCD observers to follow." From now until the object is no longer observable with your equipment (quiescence is r/i 20, V 22.3), UBV photometry is requested in the form of nightly snapshot observations (once to a few times per night). However, more frequent observations are also welcome. Sivakoff writes: "[The recurring rapid dips]...might be interesting for some observers to go after. These dips can be on the order of a minute long. Observers wishing to probe that should go for as fast observations as the telescope allows for them to get a SNR of 10-20 in their telescope. To capture the longer term evolution, an hourly cadence would be wonderful...U B V places a priority on the blue filters, which are typically harder to get at higher Galactic extinction (lower Galactic latitude). That being said, I would definitely request that some observers get V data to connect with the daily SMARTS campaign (V I J K)...if people can get down to I 17 - 18, then...Ic is good for connecting with the SMARTS campaign and LCOGT work on this source." Precision of the photometry is requested to be at least 0.05 to 0.1 magnitude if possible, with allowance for it to go down to 0.2 mag as the source becomes fainter. A S/N of 10-20, and 5 at a minimum, is requested. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

V390 Nor = Nova Normae 2007

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2007-06-01

Nova Normae 2007 was discovered photographically by William Liller on June 15.086 UT at magnitude 9.4. Precise position measured by G. Bolt from his unfiltered CCD image of June 16.7 UT: 16:32:11.51 -45:09:13.4 (2000.0). Giorgio Di Scala reported to the AAVSO that a low-resolution spectrum indicates a nova a week or so after outburst, with strong H-alpha emission. E. Kazarovets, Sternberg Astronomical Institute, reports that N Nor 07 has been assigned the name V390 Nor. Discovery originally announced in IAU Central Bureau Electronic Telegram 982 (Daniel W. E. Green) and AAVSO Special Notice #49 (Arne Henden). Information in this Alert Notice was received at AAVSO from William Liller, Giorgio Di Scala, or via IAU Circular No. 8850, ed. Daniel W. E. Green. A chart for V390 Nor is available via the Variable Star Plotter (VSP). Go to: http://www.aavso.org/observing/charts/vsp/ and enter the name V390 NOR.

ASASSN-17fp rebrightening event and ongoing monitoring

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2017-05-01

ASASSN-17fp, discovered on 2017 April 28 and classified as a helium dwarf nova, was observed to be in outburst again on May 16 after fading 2.5 magnitudes from its original outburst. Dr. Tom Marsh (University of Warwick) and Dr. Elme Breedt (University of Cambridge) requested immediate time-series coverage. Dr. Breedt wrote: "The transient was identified as a helium dwarf nova (also known as an AMCVn star) from a spectrum taken by the PESSTO survey and reported in ATel #10334. Since then, we have been observing the target using the New Technology Telescope on La Silla in Chile. We measured a photometric period of 51 minutes in the first few nights during which the object was bright at g=16.03 (Marsh et al., ATel #10354), and then it faded to about g 18. However last night [ May 16] it brightened back to g 16 again, apparently starting a second outburst. Time series observations during this bright state would be very valuable to determine whether the 51 min period we saw in earlier data returns, and whether it is the orbital period of the binary or related to the distortion of the accretion disc in outburst (superhumps). If the 51 min signal is the orbital period or close to it, this would be the helium dwarf nova with the longest orbital period known. Multiple successive outbursts are not uncommon in binaries like this..." Observers should continue to monitor ASASSN-17fp with nightly snapshots for two weeks after it fades, in case it rebrightens again. It appears to have faded, according to an observation in the AAVSO International Database by F.-J. Hambsch (HMB, Mol, Belgium), who observed it remotely from Chile on 2017 May 24.2252 UT at magnitude 19.944 CV ± 0.595. Continue nightly snapshots through June 6 at least, and if it brightens again, resume time series. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Databa! se. See full Alert Notice for more details.

Sparsely-Observed Pulsating Red Giants in the AAVSO Observing Program

NASA Astrophysics Data System (ADS)

Percy, J. R.

2018-06-01

This paper reports on time-series analysis of 156 pulsating red giants (21 SRa, 52 SRb, 33 SR, 50 Lb) in the AAVSO observing program for which there are no more than 150-250 observations in total. Some results were obtained for 68 of these stars: 17 SRa, 14 SRb, 20 SR, and 17 Lb. These results generally include only an average period and amplitude. Many, if not most of the stars are undoubtedly more complex; pulsating red giants are known to have wandering periods, variable amplitudes, and often multiple periods including "long secondary periods" of unknown origin. These results (or lack thereof) raise the question of how the AAVSO should best manage the observation of these and other sparsely-observed pulsating red giants.

A New Binary Star System of EW Type in Draco: GSC 03905-01870

NASA Astrophysics Data System (ADS)

Barquin, S.

2018-05-01

Discovery of a new binary star system (GSC 03905-01870 = USNO-B1.0 1431-0327922 = UCAC4 716-059522) in the Draco constellation is presented. It was discovered during a search for previously unreported eclipsing binary stars through the ASAS-SN database. The shape of the light curve and its characteristics (period of 0.428988+-0.000001 d, amplitude of 0.34+-0.02 V Mag, primary minimum epoch HJD 2457994.2756+-0.0002) indicates that the new variable star is an eclipsing binary of W Ursae Majoris type. I registered this variable star in The International Variable Star Index (VSX), its AAVSO UID is 000-BMP-891.

Visual Observing Manual | aavso.org

Science.gov Websites

Institute CCD School Videos Student Projects Two Eyes, 3D Variable Star Astronomy H-R Diagram Plotting Student Projects Two Eyes, 3D Variable Star Astronomy H-R Diagram Plotting Activity Reporting Variable

Aperture Fever and the Quality of AAVSO Visual Estimates: mu Cephei as an Example

NASA Astrophysics Data System (ADS)

Turner, D. G.

2014-06-01

(Abstract only) At the limits of human vision the eye can reach precisions of 10% or better in brightness estimates for stars. So why did the quality of AAVSO visual estimates suddenly drop to 50% or worse for many stars following World War II? Possibly it is a consequence of viewing variable stars through ever-larger aperture instruments than was the case previously, a time when many variables were observed without optical aid. An example is provided by the bright red supergiant variable mu Cephei, a star that has the potential to be a calibrating object for the extragalactic distance scale if its low-amplitude brightness variations are better defined. It appears to be a member of the open cluster Trumpler 37, so its distance and luminosity can be established provided one can pinpoint the amount of interstellar extinction between us and it. mu Cep appears to be a double-mode pulsator, as suggested previously in the literature, but with periods of roughly 700 and 1,000 days it is unexciting to observe and its red color presents a variety of calibration problems. Improving quality control for such variable stars is an issue important not only to the AAVSO, but also to science in general.

The AAVSO 2011 Demographic and Background Survey

NASA Astrophysics Data System (ADS)

Price, A.

2012-04-01

In 2011, the AAVSO conducted a survey of 615 people who are or were recently active in the organization. The survey included questions about their demographic background and variable star interests. Data are descriptively analyzed and compared with prior surveys. Results show an organization of very highly educated, largely male amateur and professional astronomers distributed across 108 countries. Participants tend to be loyal, with the average time of involvement in the AAVSO reported as 14 years. Most major demographic factors have not changed much over time. However, the average age of new members is increasing. Also, a significant portion of the respondents report being strictly active in a non-observing capacity, reflecting the growing mission of the organization. Motivations of participants are more aligned with scientific contribution than with that reported by other citizen science projects. This may help explain why a third of all respondents are an author or co-author of a paper in an astronomical journal. Finally, there is some evidence that participation in the AAVSO has a greater impact on the respondents' view of their role in astronomy compared to that expected through increasing amateur astronomy experience alone.

VizieR Online Data Catalog: Mira stars discovered in LAMOST DR4 (Yao+, 2017)

NASA Astrophysics Data System (ADS)

Yao, Y.; Liu, C.; Deng, L.; de Grijs, R.; Matsunaga, N.

2017-10-01

By the end of 2016 March, the wide-field Large sky Area Multi-Object fiber Spectroscopic Telescope (LAMOST) DR4 catalog had accumulated 7681185 spectra (R=1800), of which 6898298 were of stars. We compiled a photometrically confirmed sample of Mira variables from the Kiso Wide-Field Camera (KWFC) Intensive Survey of the Galactic Plane (KISOGP; Matsunaga 2017, arXiv:1705.08567), the American Association of Variable Star Observers (AAVSO) International Database Variable Star Index (VSX; Watson 2006, B/vsx, version 2017-05-02; we selected stars of variability type "M"), and the SIMBAD Astronomical Database. We first cross-matched the KISOGP and VSX Miras with the LAMOST DR4 catalog. Finally, we cross-matched the DR4 catalog with the SIMBAD database. See section 2. (1 data file).

eJAAVSO | aavso.org

Science.gov Websites

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R Aqr observing campaign

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2016-01-01

Dr. George Wallerstein (University of Washington) has requested AAVSO coverage of the long period/symbiotic variable R Aquarii beginning immediately in support of high resolution spectroscopic observations planned for 2016 January 19 and 21. Several other astronomers, including Drs. Lee Anne Willson (Iowa State University), Ulisse Munari (INAF, Astronomical Observatory of Padua, Italy), and Fred Walter (Stony Brook University) are studying R Aqr closely and additional spectroscopic and other observations are planned for the near future. R Aqr is both a Mira (M) and a symbiotic (ZAND) - it is a close binary system consisting of a hot star and a late-type star (the Mira), both enveloped in nebulosity. As a result, the very interesting light curve shows not only the Mira pulsation but also complex eclipse behavior as the two stars interact. The period of Mira variation is 387.0 days; the eclipse period is 43.6-44 years. The cause of the eclipse is unknown; several theories h! ave been proposed, including a focused accretion stream, a disk or cloud around the secondary, and a triggered mass loss that produces an opaque cloud. Careful investigation of this upcoming event should help to resolve this question. The last eclipse of R Aqr was in 1978. The next eclipse is predicted for 2022, but may be early. The current behavior of R Aqr suggests that the eclipse, which lasts for several years, may either be beginning or its beginning may be imminent. R Aqr was at minimum in early December 2015 at magnitude V=11.4, and is currently at visual magnitude 11.0. During this phase of the approximately 44-year eclipse cycle, at maximum it may be as bright as V 6.0-6.5 but is not expected to become brighter. Beginning immediately, nightly BVRI CCD and DSLR photometry and visual observations are requested. As R Aqr brightens towards maximum and is in range, PEP observations are also requested. Ongoing spectroscopy over the next several years will be interesting to see as the system evolves throughout the eclipse. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

Margaret W. Mayall in the AAVSO Archives

NASA Astrophysics Data System (ADS)

Saladyga, M.

2012-06-01

(Abstract only) AAVSO Director Margaret W. Mayall's presence in the AAVSO Archives is unique in that it was only by her effort that the AAVSO's institutional memory survived the organization's years of struggle. The history of the AAVSO could not have been written thoroughly and accurately without its archival collections. Similarly, the story of Mayall and the AAVSO within that history is not only informed, but is also formed by the materials that she chose to collect and preserve over the years.

20 Cataclysmic variables to be observed by William Herschel Telescope

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2016-05-01

Roque Ruiz-Carmona (Ph.D. candidate, Institute of Mathematics, Astrophysics and Particle Physics, Radboud University Nijmegen, The Netherlands) has requested AAVSO assistance with his campaign to observe a set of 20 cataclysmic variables (CVs) with the William Herschel Telescope (WHT) at La Palma TONIGHT. This campaign is identical in format to the ones successfully carried out by the AAVSO on his behalf in 2015 (AAVSO Alert Notices 524 and 527). The full details of and instructions for this campaign are included here although the first of the two nights for which data are requested has passed. In order for WHT to observe each of the targets safely and to maximize the science value of the observations obtained, it is essential to know whether they are in outburst or quiescence. To this end, the PI has requested our observers to obtain one image of each target on each of TWO separate nights so he may analyze them to determine the final observing list for WHT. The images must be taken and posted within a certain window. Links to finder charts as well as reporting instructions and other information may be found in the full Alert Notice.

Studies of the Long Secondary Periods in Pulsating Red Giants. II. Lower-Luminosity Stars

NASA Astrophysics Data System (ADS)

Percy, J. R.; Leung, H. W.

2017-06-01

We have used AAVSO visual and photoelectric V data, and the AAVSO time-series package VSTAR and the Lomb-Scargle time-series algorithm to determine improved pulsation periods, "long secondary periods" (LSPs), and their amplitudes in 51 shorter-period pulsating red giants in the AAVSO photoelectric photometry program, and in the AAVSO long-period variable (LPV) binocular program. As is well known, radial pulsation becomes detectable in red giants at about spectral type M0, with periods of about 20 days. We find that the LSP phenomenon is also first detectable at about M0. Pulsation and LSP amplitudes increase from near zero to about 0.1 at pulsation periods of 100 days. At longer periods, the pulsation amplitudes continue to increase, but the LSP amplitudes are generally between 0.1 and 0.2 on average. The ratios of LSP to pulsation period cluster around 5 and 10, presumably depending on whether the pulsation period is the fundamental or first overtone. The pulsation and LSP phase curves are generally close to sinusoidal, except when the amplitude is small, in which case they may be distorted by observational scatter or, in the case of the LSP amplitude, by the pulsational variability. As with longer-period stars, the LSP amplitude i ncreases and decreases by a factor of two or more, for unknown reasons, on a time scale of about 20 LSPs. The LSP phenomenon is thus present and similar in radially pulsating red giants of all periods. Its cause remains unknown.

X-ray nova and LMXB V404 Cyg in rare outburst

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2015-06-01

V404 Cyg, an X-ray nova and a low mass X-ray binary (LMXB) with black hole component, is undergoing its first reported X-ray and optical outburst since 1989. Large scale, rapid variations are being reported in wavelengths from X-ray to radio by professional and amateur astronomers worldwide. Satellite and ground-based observations have been and are continuing to be made by many members of the professional community, including S. D. Barthelmy et al. (GCN Circular 17929, 15 June 2015, Swift BAT initial detection); H. Negoro et al. (ATel #7646, 17 Jun 2015); E. Kuulkers et al. (ATel #7647, 17 June 2015, Swift observations); K. Gazeas et al. (ATel #7650, 17 June 2015, optical photometry); R. M. Wagner et al. (ATel #7655, 18 June, optical spectroscopy); K. Mooley et al. (ATel #7658, 18 June, radio observations). T. Munoz-Darias et al. report P Cyg profiles were seen on 18 Jun 2015 (ATel #7659). They note that P-Cyg profiles were also observed during the 1989 outburst (Casares et al. 1991, MNRAS, 250, 712), and that V404 Cyg is so far the only black hole X-ray transient that has shown this phenomenology. Observations in all bands are requested. Filtered observations are preferred. Please use a cadence as high as possible while obtaining a suitable s/n. If spectroscopy is possible with your equipment, it is requested. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. Precise observing instructions and other details are given in the full Alert Notice.

Eggen Card Project: Progress and Plans (Abstract)

NASA Astrophysics Data System (ADS)

Silvis, G.

2016-12-01

(Abstract only) The Eggen Card Project has been running since 2009 and has involved 30+ AAVSO staff and volunteers. Let me offer a short review of the project, our progress this year and our plans for the future. Phase 1 of the project has been to index the 108,000 card images, identifying the stars they belong too. We've passed the 75% point on this phase. The next phase is how to use this data. Jack Crast has identified the photometric schemes used by Olin and developed a spreadsheet tool to prepare this data for inclusion into the AAVSO International Database (AID). Anyone want good photometry from 1970? We got it!

Advancing Variable Star Astronomy: The Centennial History of the American Association of Variable Star Observers

NASA Astrophysics Data System (ADS)

Williams, Thomas R.; Saladyga, Michael

2011-05-01

Preface; Part I. Pioneers in Variable Star Astronomy Prior to 1909: 1. The emergence of variable star astronomy - a need for observations; 2. A need for observers; Part II. The Founding of the AAVSO - The William Tyler Olcott Era: 3. The amateur's amateur; 4. Amateurs in the service of science; Part III. The Leon Campbell Era: 5. Leon Campbell to the rescue; 6. Formalizing relationships; 7. The Pickering Memorial Endowment; 8. Fading of the Old Guard; 9. Growing pains and distractions; Part IV. The Service Bureau - The Margaret Mayall Era: 10. Learning about independence; 11. Eviction from Harvard College Observatory; 12. Actions and reactions; 13. In search of a home; 14. Survival on Brattle Street; 15. AAVSO achievements; 16. Breathing room on Concord Avenue; Part V. Analysis and Science: The Janet Mattei Era: 17. The growth of a director; 18. Learning the ropes the hard way; 19. Managing with renewed confidence; 20. Expanding the scientific charter; Part VI. Accelerating Observational Science - The Arne Henden Era: 21. Bridging the gap; 22. Accelerating the science - the Henden era begins; Epilogue; Appendices; Index.

Janet Akyüz Mattei (1943-2004)

NASA Astrophysics Data System (ADS)

Pickard, R. D.

2004-06-01

It is with great sadness that we report that Dr Janet A. Mattei, the Director of the American Association of Variable Star Observers (AAVSO), died on 2004 March 22 after a seven-month battle with acute myelogenous leukaemia.

Visual Times of Maxima for Short Period Pulsating Stars II

NASA Astrophysics Data System (ADS)

Samolyk, G.

2017-12-01

This compilation contains 631 times of maxima of 8 short period pulsating stars (primarily RR Lyrae). These were reduced from a portion of the visual observations made from 1966 to 2014 that are included in the AAVSO International Database.

KIC 8462852 optical dipping event

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2017-05-01

T. Boyajian (Louisiana State University) et al. reported in ATel #10405 that an optical dip is underway in KIC 8462852 (Boyajian's Star, Tabby's Star) beginning on 2017 May 18 UT. Tentative signs of small dips had been seen beginning April 24, and enhanced monitoring had begun at once at Fairborn Observatory (Tennessee State University). Photometry and spectroscopy from there on May 18 and 19 UT showed a dip underway. Cousins V photometry showed a drop of 0.02 magnitude, the largest dip (and the first clear one) seen in more than a year of monitoring. AAVSO observer Bruce Gary (GBL, Hereford, AZ) carried out V photometry which showed a fading from 11.906 V ± 0.004 to 11.9244 V ± 0.0033 between UT 2017 May 14 and May 19, a drop of 1.7%. Swift/UVOT observations obtained May 18 15:19 did not show a statistically significant drop in v, but Gary's photometry is given more weight. r'-band observations from Las Cumbres Observatory obtained 2017 May 17 to May 19 showed a 2% dip. Spectra by I. Steele (Liverpool JMU) et al. taken on 2017 May 20 with the 2.0 meter Liverpool Telescope, La Palma, showed no differences in the source compared to a reference spectrum taken 2016 July 4 when the system was not undergoing a dip (ATel #10406).Dips typically last for a few days, and larger dips can last over a week. It is not clear that this dip is over. Precision time-series V photometry is urgently requested from AAVSO observers, although all photometry is welcome. Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). See full Alert Notice for more details. KIC 8462852 was the subject of AAVSO Alert Notices 532 and 542. See also Boyajian et al. 2016, also available as a preprint (http://arxiv.org/abs/1509.03622). General information about KIC 8462852 may be found at http://www.wherestheflux.com/.

VStar: Variable star data visualization and analysis tool

NASA Astrophysics Data System (ADS)

VStar Team

2014-07-01

VStar is a multi-platform, easy-to-use variable star data visualization and analysis tool. Data for a star can be read from the AAVSO (American Association of Variable Star Observers) database or from CSV and TSV files. VStar displays light curves and phase plots, can produce a mean curve, and analyzes time-frequency with Weighted Wavelet Z-Transform. It offers tools for period analysis, filtering, and other functions.

Leslie Peltier, Amateur Astronomer and Observer Extraordinaire

NASA Astrophysics Data System (ADS)

Corbin, B. G.

2003-12-01

Leslie Copus Peltier, (Jan. 2, 1900-May 10, 1980) was called "the world's greatest non-professional astronomer" by none other than Harlow Shapley, and also referred to as the "the world's greatest living amateur astronomer". He began observing variable stars on March 1, 1918 with an observation of R. Leonis and at the time of his death had made a total of 132,123 observations of variable stars. These were reported to the AAVSO on a consecutive monthly basis stretching from 1918 to his death in 1980. As of October 2003, he was still on AAVSO's list of the top 25 observers in its history. Born on a farm near Delphos, Ohio, his parents were well read and their home was filled with books on different subjects, including nature guides. As a young man he studied the flora and fauna of the area and in 1915 began his study of the heavens with Vega being the first star he identified. After the purchase of a 2-inch spyglass, his observations of variable stars began to be noticed by professional astronomers and the AAVSO loaned him a 4-inch Mogey refractor; shortly thereafter Henry Norris Russell of Princeton loaned him via the AAVSO a 6-inch refractor, a comet seeker of short focus. He discovered 12 comets, 10 of which carry his name, and 6 novae or recurring novae. His design of the "Merry-Go-Round Observatory" was a novel approach with the whole observatory revolving around the observer while seated in his observing chair. Miami University (Ohio) later donated to him their 12-inch Clark refractor with its dome. His first book, Starlight Nights: The Adventures of a Star-Gazer, appeared in 1965. This autobiography, an ode to the joys of observing both the night sky and nature, was written in beautifully descriptive language that helped lead countless readers into astronomy. Departing from astronomy, in 1977 he published The Place on Jennings Creek. Written in the style of the 19th century naturalist, the book was devoted to his family's home, Brookhaven, and its natural surroundings. Peltier was a shy person who rarely left Delphos, and worked as a designer of children's furniture and toys until his death. However, he was widely recognized during his lifetime with articles about him appearing in popular magazines such as Reader's Digest and Newsweek. Many famous astronomers visited him at Delphos including W.W. Morgan, W.A. Hiltner, Donald Menzel, the Boks, and others. He received many honors including an honorary Doctor of Science degree from Bowling Green State University (Ohio) and the AAVSO's first Merit Award in 1934. Starlight Nights returned to print in 1999 with a foreword by David Levy, and is now introducing a new generation to the beauty and thrill of observing.

Nova in Ophiuchus

NASA Astrophysics Data System (ADS)

Templeton, Matthew R.

2009-08-01

Nova Ophiuchi 2009 was discovered by Koichi Itagaki, Teppo-Cho, Yamagata, Japan, at unfiltered CCD magnitude 10.1 on August 16.515 UT, and confirmed by him on Aug. 16.526. After posting to the CBET Unconfirmed Observations page, the object was confirmed independently by several observers. The discovery and confirmatory information were intially reported in CBET 1910, CBET 1911, and AAVSO Special Notice #166. The nova, located in a very crowded field within the Milky Way, is reported by T. Kato (vsnet-alert 11399) to have a large B-V (+1.6), indicating it is highly reddened. N Oph 2009 has been assigned the identifiers VSX J173819.7-264413 and the AUID 000-BJP-605. Please submit observations to the AAVSO International Database using the name N OPH 2009.

Monitoring of V2487 Oph requested

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2016-10-01

Dr. Ashley Pagnotta (Louisiana State University) has requested AAVSO assistance in monitoring the recurrent nova V2487 Oph in order to catch and observe its next outburst. Pagnotta writes: "V2487 Oph is a recurrent nova that was first seen to erupt in 1998. During a search of the Harvard College Observatory plate archives for previous eruptions, we found one that was recorded in 1900. Based on the speed and magnitude of the eruption, and the coverage of the archival plates and other detection sources, we calculated how often V2487 Oph would have to erupt for us to have actually detected one random outburst on the plates, which is about once every 18-20 years (for more, Pagnotta et al. 2009AJ....138.1230P). As we are now 18 years from the previous (1998) eruption, we request regular AAVSO observations to help us detect the next eruption of V2487 Oph. Because V2487 Oph is a very fast nova, we are requesting a high cadence [when the outburst occurs. Previous outbursts have been as bright as V=9.5.]...Once the eruption has been confirmed (likely by other AAVSO observers, thanks to the flexibility of your observing programs), we will notify collaborators and invoke ToO observations to observe the eruption as comprehensively as possible." Observers are requested to make nightly observations in V or Clear. If V2487 Oph is brighter than V=17.5, please report the observation(s) to the AAVSO immediately and switch to multi-color (UBVRI or Sloan equivalents; Clear if other filters are not available) and high (fast) cadence time-series - exposures of a few minutes, with a S/N of at least 40-50. Continue at high cadence until the decline is underway. Time-series observations during the decline are not absolutely essential, but they would be useful to continue to look for flares and the late time dips that were seen in U Sco around days 41-61. Nightly observations as before should be continued until the star has faded to V=17.5, and then for two weeks m! ore. Finder charts with sequence may be created using the AAVS! O Variab le Star Plotter (https://www.aavso.org/vsp). Observations should be submitted to the AAVSO International Database. See full Alert Notice for more details.

The Birch Street Irregulars: mysteries found and resolved in the AAVSO data archives

NASA Astrophysics Data System (ADS)

Beck, Sara J.; Saladyga, Michael; Mattei, Janet A.

As they evaluate AAVSO data, AAVSO technical staff members run across several kinds of errors. This paper takes a humorous and Sherlock Holmes-style look at some of the most common kinds of errors detected, from observers recording the wrong Julian Date, misidentifying stars, transposing entries on the observer form, to garden-variety data entry errors.

V694 Mon (MWC 560) spectroscopy requested

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2017-05-01

The observing campaign from 2016 on V694 Mon (MWC 560) (AAVSO Alert Notice 538) has been continued, but with different requirements. Photometry is no longer specifically requested on a regular basis (although ongoing observations that do not interfere with other obligations are welcome). Spectroscopy on a cadence of a week or two is requested to monitor changes in the disk outflow. Investigator Adrian Lucy writes: "Adrian Lucy and Dr. Jeno Sokoloski (Columbia University) have requested spectroscopic monitoring of the broad-absorption-line symbiotic star V694 Mon (MWC 560), as a follow-up to coordinated multi-wavelength observations obtained during its recent outburst (ATel #8653, #8832, #8957; #10281). This system is a perfect place in which to study the relationship between an accretion disk and disk winds/jets, and a high-value target for which even low-resolution spectra can be extraordinarily useful...Optical brightening in MWC 560 tends to predict higher-velocity absorption, but sometimes jumps in absorption velocity also appear during optical quiescence (e.g., Iijima 2001, ASPCS, 242, 187). If such a velocity jump occurs during photometric quiescence, it may prompt radio observations to confirm and test the proposed outflow origin for recently-discovered flat-spectrum radio emission (Lucy et al. ATel #10281)...Furthermore, volunteer spectroscopic monitoring of this system has proved useful in unpredictable ways. For example, 'amateur' spectra obtained by Somogyi Péter in 2015 December demonstrated that the velocity of absorption was very low only a month before an optical outburst peak prompted absorption troughs up to 3000 km/s, which constrains very well the timing of the changes to the outflow to a degree that would not have been otherwise possible. Any resolution can be useful. A wavelength range that can accommodate a blueshift of at least 140 angstroms (6000 km/s) from the rest wavelengths of H-alpha at 6562 angstroms and/or H-beta at 4861 angstroms is ideal, though spectra with a smaller range can still be useful. Photometry could potentially still be useful, but will be supplementary to medium-cadence photometry being collected by the ANS collaboration." "Spectroscopy may be uploaded to the ARAS database (http://www.astrosurf.com/aras/Aras_DataBase/DataBase.htm), or sent to Adrian and Jeno directly at . Finder charts with sequence may be created using the AAVSO Variable Star Plotter (https://www.aavso.org/vsp). Photometry should be submitted to the AAVSO International Database. See full Special Notice for more details.

The VSS RASNZ Variable Star Charts: a Story of Co-Evolution

NASA Astrophysics Data System (ADS)

Plummer, A.; Morel, M.

2010-06-01

The background and history of the Charts for Southern Variables of the Variable Star Section of the Royal Astronomical Society of New Zealand (VSS RASNZ) is presented. It is seen that while there are some common origins with the charts of the AAVSO, they have undergone their own unique and important development. After much effort the two organizations' chart resources are now compatible and complementary. Some more general but nonetheless important history of the VSS is also mentioned.

Citizen Sky, An Update on the AAVSO's New Citizen Science Project

NASA Astrophysics Data System (ADS)

Turner, Rebecca; Price, A.; Henden, A.; Stencel, R.; Kloppenborg, B.

2011-01-01

Citizen Sky is a multi-year, NSF-funded, citizen science project focusing on the bright variable star, epsilon Aurigae. Citizen Sky goes beyond simple observing to include a major data analysis component. The goal is to introduce the participant to the full scientific process from background research to paper writing for a peer-reviewed journal. The first year of the project, 2009-10, was dedicated to developing project infrastructure, educating participants about epsilon Aurigae, and training these participants to observe the star and report their data. Looking forward, years two and three of the project will focus on assembling teams of participants to work on their own analysis and research. Results will be published in a special issue of the peer-reviewed Journal of the AAVSO. This project has been made possible by the National Science Foundation.

An Overview of the Evolution of the AAVSO's Information Technology Infrastructure Between 1965-1997

NASA Astrophysics Data System (ADS)

Kinne, Richard C. S.; Saladyga, M.; Waagen, E. O.

2011-05-01

We trace the history and usage of computers and data processing equipment at the AAVSO HQ between its beginings in the 1960s to 1997. We focus on equipment, people, and the purpose such computational power was put to use. We examine how the AAVSO evolved its use of computing and data processing resources as the technology evolved in order to further its mission.

Studies of the Long Secondary Periods in Pulsating Red Giants

NASA Astrophysics Data System (ADS)

Percy, J. R.; Deibert, E.

2016-12-01

We have used systematic, sustained visual observations from the AAVSO International Database and the AAVSO time-series analysis package VSTAR to study the unexplained "long secondary periods" (LSPs) in 27 pulsating red giants. In our sample, the LSPs range from 479 to 2967 days, and are on average 8.1 +/- 1.3 times the excited pulsation period. There is no evidence for more than one LSP in each star. In stars with both the fundamental and first overtone radial period present, the LSP is more often about 10 times the latter. The visual amplitudes of the LSPs are typically 0.1 magnitude and do not correlate with the LSP. The phase curves tend to be sinusoidal, but at least two are sawtooth. The LSPs are stable, within their errors, over the timespan of our data, which is typically 25,000 days. The amplitudes, however, vary by up to a factor of two or more on a time scale of roughly 20-30 LSPs. There is no obvious difference between the carbon (C) stars and the normal oxygen (M) stars. Previous multicolor observations showed that the LSP color variations are similar to those of the pulsation period, and of the LSPs in the Magellanic Clouds, and not like those of eclipsing stars. We note that the LSPs are similar to the estimated rotation periods of the stars, though the latter have large uncertainties. This suggests that the LSP phenomenon may be a form of modulated rotational variability.

Low-Frequency Temporal Variability in Mira and Semiregular Variables

NASA Astrophysics Data System (ADS)

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.

Visual photometry: accuracy and precision

NASA Astrophysics Data System (ADS)

Whiting, Alan

2018-01-01

Visual photometry, estimation by eye of the brightness of stars, remains an important source of data even in the age of widespread precision instruments. However, the eye-brain system differs from electronic detectors and its results may be expected to differ in several respects. I examine a selection of well-observed variables from the AAVSO database to determine several internal characteristics of this data set. Visual estimates scatter around the fitted curves with a standard deviation of 0.14 to 0.34 magnitudes, most clustered in the 0.21-0.25 range. The variation of the scatter does not seem to correlate with color, type of variable, or depth or speed of variation of the star’s brightness. The scatter of an individual observer’s observations changes from star to star, in step with the overall scatter. The shape of the deviations from the fitted curve is non-Gaussian, with positive excess kurtosis (more outlying observations). These results have implications for use of visual data, as well as other citizen science efforts.

Transits, Spots, and Eclipses: The Sunís Role in Pedagogy and Outreach (Abstract)

NASA Astrophysics Data System (ADS)

Larsen, K.

2018-06-01

(Abstract only) While most people observe variable stars at night, the observers of the AAVSO Solar Section make a single observation per day, but only if it is sunny, because our variable is the Sun itself. While the Sun can play an important role in astronomy outreach and pedagogy in general, as demonstrated by the recent 2017 eclipse, it can also serve as an ambassador for variable stars. This talk will examine how our sun can be used as a tool to explain several types of variable star behaviors, including transits, spots, and eclipses.

The great red flashlight

NASA Astrophysics Data System (ADS)

Halbach, Edward A.

After fifty years of fighting with flashlights which persisted in rolling to the ground, being mislaid, or stashed in a pocket, the author designed a unit which was always on hand and needed no search for the switch. A normally closed switch, internal to the bottom of the flashlight case, is opened by the weight of the unit suspended on a cord about the neck. Lifting the unit with two fingers turns on the red light, while releasing the unit automatically turns it off. A felt covering around the flashlight provides comfort on cold nights. Because this red light would be a welcome tool for other variable star observers, more units were assembled and brought to the AAVSO meeting in Houston for distribution to observers who agreed to give each unit a workout and report on its performance. The author is waiting to hear from these observers.

Visual Times of Maxima for Short Period Pulsating Stars III

NASA Astrophysics Data System (ADS)

Samolyk, G.

2018-06-01

Abstract This compilation contains 524 times of maxima of 9 short period pulsating stars (primarily RR Lyrae stars; RW Cnc, TT Cnc, VZ Cnc, RR Cet, XZ Cyg, DM Cyg, RW Dra, XZ Dra, RR Gem). These were reduced from a portion of the visual observations made from 1966 to 2014 that are included in the AAVSO International Database.

Watching Stars Grow: The adaptation and creation of instructional material for the acquisition, reduction, and analysis of data using photometry tools at the WestRock Observatory.

NASA Astrophysics Data System (ADS)

O'Keeffe, Brendon; Johnson, Michael; Murphy Williams, Rosa Nina

2018-06-01

The WestRock observatory at Columbus State University provides laboratory and research opportunities to earth and space science students specializing in astrophysics and planetary geology. Through continuing improvements, the observatory has been expanding the types of research carried out by undergraduates. Photometric measurements are an essential tool for observational research, especially for objects of variable brightness.Using the American Association of Variable Star Observers (AAVSO) database, students choose variable star targets for observation. Students then perform observations to develop the ability to properly record, calibrate, and interpret the data. Results are then submitted to a large database of observations through the AAVSO.Standardized observation procedures will be developed in the form of manuals and instructional videos specific to the equipment housed in the WestRock Observatory. This procedure will be used by students conducting laboratory exercises and undergraduate research projects that utilize photometry. Such hands-on, direct observational experience will help to familiarize the students with observational techniques and contribute to an active dataset, which in turn will prepare them for future research in their field.In addition, this set of procedures and the data resulting from them will be used in the wider outreach programs of the WestRock Observatory, so that students and interested public nationwide can learn about both the process and importance of photometry in astronomical research.

Time Series Observations of the 2015 Eclipse of b Persei (not beta Persei) (Abstract)

NASA Astrophysics Data System (ADS)

Collins, D. F.

2016-06-01

(Abstract only) The bright (V = 4.6) ellipsoidal variable b Persei consists of a close non-eclipsing binary pair that shows a nearly sinusoidal light curve with a ~1.5 day period. This system also contains a third star that orbits the binary pair every 702 days. AAVSO observers recently detected the first ever optical eclipse of A-B binary pair by the third star as a series of snapshots (D. Collins, R. Zavala, J. Sanborn - AAVSO Spring Meeting, 2013); abstract published in Collins, JAAVSO, 41, 2, 391 (2013); b Per mis-printed as b Per therein. A follow-up eclipse campaign in mid-January 2015 recorded time-series observations. These new time-series observations clearly show multiple ingress and egress of each component of the binary system by the third star over the eclipse duration of 2 to 3 days. A simulation of the eclipse was created. Orbital and some astrophysical parameters were adjusted within constraints to give a reasonable fit to the observed light curve.

Amplitude Variations in Pulsating Red Giants. II. Some Systematics

NASA Astrophysics Data System (ADS)

Percy, J. R.; Laing, J.

2017-12-01

In order to extend our previous studies of the unexplained phenomenon of cyclic amplitude variations in pulsating red giants, we have used the AAVSO time-series analysis package vstar to analyze long-term AAVSO visual observations of 50 such stars, mostly Mira stars. The relative amount of the variation, typically a factor of 1.5, and the time scale of the variation, typically 20-35 pulsation periods, are not significantly different in longer-period, shorter-period, and carbon stars in our sample, and they also occur in stars whose period is changing secularly, perhaps due to a thermal pulse. The time scale of the variations is similar to that in smaller-amplitude SR variables, but the relative amount of the variation appears to be larger in smaller-amplitude stars, and is therefore more conspicuous. The cause of the amplitude variations remains unclear, though they may be due to rotational modulation of a star whose pulsating surface is dominated by the effects of large convective cells.

SpecDB: The AAVSO’s Public Repository for Spectra of Variable Stars

NASA Astrophysics Data System (ADS)

Kafka, Stella; Weaver, John; Silvis, George; Beck, Sara

2018-01-01

SpecDB is the American Association of Variable Star Observers (AAVSO) spectral database. Accessible to any astronomer with the capability to perform spectroscopy, SpecDB provides an unprecedented scientific opportunity for amateur and professional astronomers around the globe. Backed by the Variable Star Index, one of the most utilized variable star catalogs, SpecDB is expected to become one of the world leading databases of its kind. Once verified by a team of expert spectroscopists, an observer can upload spectra of variable stars target easily and efficiently. Uploaded spectra can then be searched for, previewed, and downloaded for inclusion in publications. Close community development and involvement will ensure a user-friendly and versatile database, compatible with the needs of 21st century astrophysics. Observations of 1D spectra are submitted as FITS files. All spectra are required to be preprocessed for wavelength calibration and dark subtraction; Bias and flat are strongly recommended. First time observers are required to submit a spectrum of a standard (non-variable) star to be checked for errors in technique or equipment. Regardless of user validation, FITS headers must include several value cards detailing the observation, as well as information regarding the observer, equipment, and observing site in accordance with existing AAVSO records. This enforces consistency and provides necessary details for follow up analysis. Requirements are provided to users in a comprehensive guidebook and accompanying technical manual. Upon submission, FITS headers are automatically checked for errors and any anomalies are immediately fed back to the user. Successful candidates can then submit at will, including multiple simultaneous submissions. All published observations can be searched and interactively previewed. Community involvement will be enhanced by an associated forum where users can discuss observation techniques and suggest improvements to the database.

A possible giant planet orbiting the cataclysmic variable LX Ser

NASA Astrophysics Data System (ADS)

Li, Kai; Hu, Shaoming; Zhou, Jilin; Wu, Donghong; Guo, Difu; Jiang, Yunguo; Gao, Dongyang; Chen, Xu; Wang, Xianyu

2017-04-01

LX Ser is a deeply eclipsing cataclysmic variable with an orbital period of 0.1584325 d. 62 new eclipse times were determined by our observations and the AAVSO International Data base. Combining all available eclipse times, we analyzed the O - C behavior of LX Ser. We found that the O - C diagram of LX Ser shows a sinusoidal oscillation with a period of 22.8 yr and an amplitude of 0.00035 d. Two mechanisms (i.e., the Applegate mechanism and the light-travel time effect) are applied to explain the cyclic modulation. We found that it is difficult to apply the Applegate mechanism to explain the cyclic oscillation in the orbital period. Therefore, the cyclic period change is most likely to be caused by the light-travel time effect due to the presence of a third body. The mass of the tertiary component was determined to be M3 ∼ 7.5 MJup. We supposed that the tertiary companion is plausibly a giant planet. The stability of the giant planet was checked, and we found that the multiple system is stable.

Scientists Look at 2010: Carrying on Margaret Mayall's Legacy of Debunking Pseudoscience

NASA Astrophysics Data System (ADS)

Larsen, Krinstine

2010-06-01

In 1941 Margaret Mayall, the future director of the AAVSO, and Harvard colleague Bart Bok authored a critical study of astrology and its impact on society entitled "Scientists Look at Astrology." They chastised the scientific community for thinking the debunking of astrology to be "below the dignity of scientists." In contrast, they opined that it is one of the duties of scientists to "inform the public about the nature and background of a current fad, such as astrology, even though to do so may be unpleasant." Fast-forward 68 years in the future, and the astronomical community now faces a pseudoscientific enemy just as insidious as astrology, yet just as ignored by the general professional and amateur community as astrology had been when Mayall and Bok took up the charge in 1941. The pseudoscience in question is the well-publicized "prediction" that the Mayan calendar will end on December 21, 2012, causing the end of civilization in concert with one of a number of possible astronomical calamities, including (but not limited to) the gravitational pull of the center of the Milky Way (somehow enhanced by an "alignment" with our solar system), the near-approach by a mythical 10th planet (often named Nibiru), large-scale damage to the planet by solar flares larger than those ever recorded, or the shifting of the earth's axis of rotation (often confused with a proposed sudden and catastrophic reversal of the earth's magnetic polarity). As a scientific and educational organization, the AAVSO and its members have a responsibility to follow in Mayall's footsteps, shining the light of reason and knowledge on the dark corners of ignorance which far too often permeate the Internet, radio and television programming, and recent films, most notably 2012. This talk will highlight some of the basic premises of the 2012 hysteria and suggest ways that the AAVSO and its members can use variable stars and the history of the AAVSO to counteract some of the astronomical misinformation which is increasingly promulgated by proponents of the 2012 pseudoscience.

Swift observations of SDSS J141118.31+481257.6 during superoutburst

NASA Astrophysics Data System (ADS)

Rivera Sandoval, L. E.; Maccarone, T.

2018-06-01

We report on follow-up Swift observations of the AM CVn-type binary SDSS J141118.31+481257.6 (ATEL #11668, #11672). Based on ground based photometry, the re-brightening previous to the current superoutburst was reported on 2018-June-1 (https://www.aavso.org/aavso-alert-notice-636).

Elizabeth Brown and Citizen Science in the Late 1800s (poster)

NASA Astrophysics Data System (ADS)

Larsen, K.

2013-06-01

(Abstract only) While "Citizen Science" projects are sometimes thought of as a recent permutation of the professional-amateur relationship in science, the AAVSO is an example of an organization that has been encouraging such participation for over a century. Although the AAVSO's Solar Observing Program dates back only to 1944, AAVSO members had been submitting sunspot counts to other agencies long before this time. Other countries also have a long history of collecting valuable sunspot observations. For example, prior to the AAVSO's founding in 1911, British amateurs had been collecting solar data in organizations such as the British Astronomical Association (BAA) and Liverpool Astronomical Society (LAS) since the 1880s. British amateur astronomer Elizabeth Brown served as Solar Section Director of both the BAA and the LAS, and played an important role in promoting participation in citizen science projects, not only in solar observing, but in other astronomical and meteorological projects as well. This poster will summarize this work and argue that Brown's contributions should be more widely known and studied in modern citizen science project circles.

Obituary: Martha Locke Hazen, 1931-2006

NASA Astrophysics Data System (ADS)

Williams, Thomas R.; Willson, Lee Anne

2007-12-01

Longtime Harvard Curator of Astronomical Photographs and AAVSO officer Martha Hazen passed away on 23 December 2006 at Hingham, Massachusetts, after a short illness due to acute myelogenous leukemia. One of four children of Harold Locke and Katherine (neé Salisbury) Hazen, Martha was born in Cambridge, Massachusetts, on 15 July 1931, and raised in the Town of Belmont, near Cambridge, where she lived for most of her life. Her father coined the term "servo-mechanism" while serving as an engineering professor and dean for graduate students at the Massachusetts Institute of Technology. Her mother majored in chemistry at Mount Holyoke College. After receiving an A.B. in astronomy from Mount Holyoke College in 1953, Martha earned a Ph.D. in astronomy in 1958 from the University of Michigan, defending a dissertation on the distribution of intensity in elliptical galaxies in the Virgo cluster. Martha's marriage to William Liller in 1959, and the births of two children, inevitably slowed down her progress in observational astronomy. As a research fellow of the Harvard College Observatory, Martha continued to observe two to three weeks a year in Chile, and to reduce those observations and publish the results for sixteen years. Martha's first publication, at least as far as Astrophysics Data System includes the literature, was with Alice Farnsworth on the 1952 occultations of stars by the Moon, published in the Astronomical Journal (1953). In 1958 she joined L. R. Doherty and D. H. Menzel on a short note about the calculation of line profiles in a stratified atmosphere, her only theory paper. Martha's most cited paper is "The Distribution of Intensity in Elliptical Galaxies of the Virgo Cluster," (ApJ, 132, p.306, 1960). There she acknowledges Allan Sandage for suggesting the problem and providing some of the data. Her second most cited paper is "Photometric histories of QSOs - Two QSOs with large light amplitude," (Liller, M. H. & Liller, W., ApJ (Letters), 199, p. L133-L135, 1975). Progressing to smaller objects, other frequently cited papers are on eta Carinae and spectroscopic binaries in the globular cluster M3. All of these, and most of her other papers, involve photographic photometry, mostly using archival data. In 1969, Harvard appointed Martha Curator of Astronomical Photographs, placing her in responsible charge of the world renowned Harvard Plate Archives. Under attack during the mid-1950s because it occupied too much physical space, the collection had been neglected for over a decade when Martha assumed this additional responsibility. Though she continued to observe for a few years thereafter, her stewardship of the invaluable plate archives gradually demanded her full attention, which it held until her retirement in 2002. In her thirty-three years as curator of the plate stacks, as the archive is popularly known, Martha made numerous friends in both the professional and amateur communities. Astronomical researchers on a wide variety of topics relied on her detailed knowledge of the collection to guide them to important discoveries or discovery confirmations on the old plates, and to historical understanding of results in which some detail of origin needed clarification. Martha researched and documented the characteristics of nearly a hundred separate telescopic cameras used to take the plates archived in the collection. Much of this information was ephemeral, having been passed orally from observer to observer and was in danger of passing from human memory. This was, in itself, an enormous and valuable undertaking as it ensures the utility of the plates for future research. More importantly, Martha conserved and catalogued the all important logbooks that record the date, time, and other exposure circumstances for each of the plates in the collection. The full measure of Martha's long-term contribution in this regard undoubtedly will be realized as the digitization of the entire collection of plates is completed. The Digital Access to a Sky Century from Harvard (DASCH) project will owe much to Martha's efforts in this regard. Another important contribution to progress in astronomy from the plate stacks came as Martha engaged in what she called Forensic Astronomy. Over the years, a great many variable stars that had been discovered on the Harvard plates had since been "lost," i. e. could not be found or verified. At the request of Nikolai Samus, General Editor of the General Catalogue of Variable Stars (GCVS), Martha found the original discovery plates on these stars together with sufficient relevant information from other sources, and was successful in re-establishing credible identifications and accurate coordinates for 1,174 of the nearly 1,200 "lost" variable stars on the GCVS list. This required looking at multiple plates of the field involved to sort out whether the problem was an erroneous identification, inappropriate coordinates for the star, or some other problem. Many astronomers, professional and amateur, have relied on Martha to teach them the now arcane skills of photovisual photometry using a time series of plates and a "fly swatter" to discover variable stars, confirm a period or period change, or simply to construct a historical light curve to fit with modern observations. The range of co-authors on Martha's many publications illustrates how useful her chosen specialization was to the field. She served as a portal to otherwise difficult-to-access but very valuable (and irreplaceable) data, particularly the Harvard Plate Collection. In the 1970s, when interest in improving the status of women in astronomy arose, along with the desire to recruit more women into astronomy, Martha was appointed as Harvard College Observatory's representative to a university-wide coordination committee on the status of women in university life generally. Working with Ursula Marvin, who had similar responsibilities for the Smithsonian Astrophysical Observatory, Martha played a leadership role in the field for several years, helping to organize the first Space for Women conference in 1975. Martha's long term support for the American Association of Variable Star Observers (AAVSO) was a natural consequence of her earlier work as an observational astronomer as well as curator of the plate stacks. She joined AAVSO in 1975, and was first elected to the Council in 1984, became a vice president, and eventually became president in 1992. When long-term AAVSO secretary Clinton Banker Ford (obituary, BAAS, 26, p. 1602-1603, 1994) passed away in February 1993, Martha was elected secretary to replace Ford, and served in that capacity for over ten years. Her services to AAVSO went well beyond those years in elective offices, however, and cannot be fully understood only in those terms. Martha also served a vital role as a friend and mentor for Janet Akyüz Mattei ((obituary, BAAS, 36, p. 1681-1682, 2004) throughout the latter's tenure as the director of AAVSO. The proximity of the plate stacks and AAVSO offices made it convenient for them to spend frequent lunch hours together, almost invariably discussing problems in administering the AAVSO. Both the authors of this obituary can testify, as former AAVSO presidents, to the importance of Martha's support and advice for Janet, and to the importance of her role behind the scenes in AAVSO activities for many years. AAVSO honored Martha for this service by presenting her their 37th Merit Award. After her first marriage ended in divorce in 1982, Martha married Bruce McHenry, a retired career professional from the National Park Service, in 1991. That their relationship was a happy and fulfilling one is attested by the many friends Bruce made among Martha's astronomical associates. Their extensive travel together frequently involved Bruce's continuing professional interest in natural-history interpretation, but also touched many astronomical bases. Their travels also took the happy couple to the sites of many old canals, an interest they shared, as well as to quilting exhibitions, another of Martha's many interests. Martha's life long contributions to astronomy were recognized by Smithsonian Astrophysical Observatory colleagues through the naming of an asteroid, (10024) Marthahazen in her honor. She is survived by Bruce; three siblings, Stanley Hazen, Nathen Hazen, and Anne Bowen; her son, John Liller and daughter, Hilary Ward; and five grandchildren.

Monitoring of RU Peg requested for Swift observations

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2012-06-01

Dr. Koji Mukai (Universities Space Research Association/NASA Goddard Space Flight Center) has requested AAVSO observers' assistance in monitoring the SS Cyg-type dwarf nova RU Peg in support of target-of-opportunity observations with the NASA Swift satellite during an outburst. His observations will be targeted during the rise to outburst and during late decline from outburst. Thus, your prompt notification to AAVSO Headquarters of activity in RU Peg will be crucial to the success of this campaign. Dr. Mukai writes: "In the famous AAVSO/EUVE/RXTE campaign on SS Cyg (Mattei et al. 2000JAVSO..28..160M), the hard X-ray flux went up (with a delay) during the rise, then suddenly dropped; there was a corresponding flux enhancement episode during the decline. We know that, during the peak of the outburst, many dwarf novae are hard X-ray fainter than in quiescence (with a few exceptions, like U Gem). However, the hard X-ray enhancement episodes seen in SS Cyg have never been obs! erved in other dwarf novae. We have proposed a hypothesis that this is related to the mass of the accreting white dwarf; only dwarf novae with a relatively massive white dwarf show the hard X-ray enhancement. If that's true, we may well see similar enhancement in RU Peg, which is thought to have a massive white dwarf. Even if this hypothesis is completely wrong, RU Peg is a good target for an SS Cyg-like campaign, since it's X-ray bright during quiescence." Visual and CCD observations (filtered preferred to unfiltered) are appropriate for this campaign. Observers are requested to monitor RU Peg duning minimum, throughout the next outburst, and after return to minimym, and report their observations in a timely manner. If RU Peg appears to be brightening from minimum, please report your observations immediately to the AAVSO. If it is brighter than magnitude 12.3, please also send an email report to Elizabeth Waagen (eowaagen@aavso.org) and Matthew Templeton (matthewt@aavso.org). Please be aware that there is a ~12.5-magnitude star 11" NE of RU Peg.

Stellar Presentations (Abstract)

NASA Astrophysics Data System (ADS)

Young, D.

2015-12-01

(Abstract only) The AAVSO is in the process of expanding its education, outreach and speakers bureau program. powerpoint presentations prepared for specific target audiences such as AAVSO members, educators, students, the general public, and Science Olympiad teams, coaches, event supervisors, and state directors will be available online for members to use. The presentations range from specific and general content relating to stellar evolution and variable stars to specific activities for a workshop environment. A presentation—even with a general topic—that works for high school students will not work for educators, Science Olympiad teams, or the general public. Each audience is unique and requires a different approach. The current environment necessitates presentations that are captivating for a younger generation that is embedded in a highly visual and sound-bite world of social media, twitter and U-Tube, and mobile devices. For educators, presentations and workshops for themselves and their students must support the Next Generation Science Standards (NGSS), the Common Core Content Standards, and the Science Technology, Engineering and Mathematics (STEM) initiative. Current best practices for developing relevant and engaging powerpoint presentations to deliver information to a variety of targeted audiences will be presented along with several examples.

Exoplanet Observing: From Art to Science

NASA Astrophysics Data System (ADS)

Conti, Dennis M.; Gleeson, Jack

2017-06-01

This paper will review the now well-established best practices for conducting high precision exoplanet observing with small telescopes. The paper will also review the AAVSO's activities in promoting these best practices among the amateur astronomer community through training material and online courses, as well as through the establishment of an AAVSO Exoplanet Database. This latter development will be an essential element in supporting followup exoplanet observations for upcoming space telescope missions such as TESS and JWST.

New Variable Stars in the KP2001 Catalog from the Data Base of the Northern Sky Variability Survey

NASA Astrophysics Data System (ADS)

Petrosyan, G. V.

2018-03-01

The optical variability of stars in the KP2001 catalog is studied. Monitor data from the automatic Northern Sky Variability Survey (NSVS) are used for this purpose. Of the 257 objects that were studied, 5 are Mira Ceti variables (mirids), 33 are semiregular (SR), and 108 are irregular variables (Ir). The light curves of the other objects show no noticeable signs of variability. For the first time, 11 stars are assigned to the semiregular and 105 stars to the irregular variables. Of the irregular variables, the light curves of two, No. 8 and No. 194, are distinct and are similar to the curves for eclipsing variables. The periods and amplitudes of the mirids and semiregular variables are determined using the "VStar" program package from AAVSO. The absolute stellar magnitudes M K and distances are also estimated, along with the mass loss for the mirids. The behavior of stars from KP2001 in 2MASS and WISE color diagrams is examined.

Exoplanet Observing: from Art to Science (Abstract)

NASA Astrophysics Data System (ADS)

Conti, D. M.; Gleeson, J.

2017-12-01

(Abstract only) This paper will review the now well-established best practices for conducting high precision exoplanet observing with small telescopes. The paper will also review the AAVSO's activities in promoting these best practices among the amateur astronomer community through training material and online courses, as well as through the establishment of an AAVSO Exoplanet Database. This latter development will be an essential element in supporting followup exoplanet observations for upcoming space telescope missions such as TESS and JWST.

The Discovery of the Optical Transient For GRB 010222

NASA Astrophysics Data System (ADS)

Henden, Arne A.

2001-04-01

On February 22, 2001, a very bright gamma-ray burst was detected by the Italian BeppoSAX satellite. The localization was posted about 4 hours after the burst. Prompt notification by phone and by the AAVSO Gamma-Ray Burst Network pager alert system resulted in the discovery of the optical afterglow within the first hour after the locatlization posting. This paper gives a brief history of the event and how the AAVSO was essential to the discovery.

Spurious One-Month and One-Year Periods in Visual Observations of Variable Stars

NASA Astrophysics Data System (ADS)

Percy, J. R.

2015-12-01

Visual observations of variable stars, when time-series analyzed with some algorithms such as DC-DFT in vstar, show spurious periods at or close to one synodic month (29.5306 days), and also at about a year, with an amplitude of typically a few hundredths of a magnitude. The one-year periods have been attributed to the Ceraski effect, which was believed to be a physiological effect of the visual observing process. This paper reports on time-series analysis, using DC-DFT in vstar, of visual observations (and in some cases, V observations) of a large number of stars in the AAVSO International Database, initially to investigate the one-month periods. The results suggest that both the one-month and one-year periods are actually due to aliasing of the stars' very low-frequency variations, though they do not rule out very low-amplitude signals (typically 0.01 to 0.02 magnitude) which may be due to a different process, such as a physiological one. Most or all of these aliasing effects may be avoided by using a different algorithm, which takes explicit account of the window function of the data, and/or by being fully aware of the possible presence of and aliasing by very low-frequency variations.

Untersuchung der Mira-Sterne RT Boo, TV Peg und VX Aur

NASA Astrophysics Data System (ADS)

Raetz, Kerstin; Berthold, Thomas

2015-02-01

The light-change of the Mira stars RT Boo, TV Peg and VX Aur was analyzed on three ways for a long time. In the first period I estimated the brightness of the variables on sky monitoring photo plates (red spectral range) from Sonneberg Observatory with Argelander¥s Method, in the last years I measured scanned photo plates with a photometry program and in addition I used visual observations from A.A.V.S.O. for the analysis. The behavior of the periods of the tree stars from 1965 to 2013 is described here.

The Stars Belong to Everyone: Astronomer and Science Writer Helen Sawyer Hogg (1905-1993)

NASA Astrophysics Data System (ADS)

Cahill, Maria J.

2012-06-01

As a scientist and science educator, Helen Sawyer Hogg served astronomy, and especially variable star astronomy, in diverse ways while raising a family. Her long interest in and support of the AAVSO over many years took place in the context of not only that busy scientific and writing career, but also one of personal struggle to achieve parity as a female in a largely male profession. This biographical sketch demonstrates that her path to eventual status as “the Canadian face of astronomy” was both difficult and filled with uncertainty.

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

NASA Astrophysics Data System (ADS)

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.

The Shape of Long Outbursts in U Gem Type Dwarf Novae from AAVSO Data

NASA Technical Reports Server (NTRS)

Cannizzo, John K.

2012-01-01

We search the American Association of Variable Star Observers (AAVSO) archives of the two best studied dwarf novae in an attempt to find light curves for long out bursts that are extremely well-characterized. The systems are U Gem and S8 Cyg. Our goal is to search for embedded precursors such as those that have been found recently in the high fidelity Kepler data for superoutbursts of some members of the 8U UMa subclass of dwarf novae. For the vast majority of AAV80 data, the combination of low data cadence and large errors associated with individual measurements precludes one from making any strong statement about the shape of the long outbursts. However, for a small number of outbursts, extensive long term monitoring with digital photometry yields high fidelity light curves. We report the finding of embedded precursors in two of three candidate long outbursts. This reinforces van Paradijs' finding that long outbursts in dwarf novae above the period gap and superoutbursts in systems below the period gap constitute a unified class. The thermal-tidal instability to account for superoutbursts in the SU UMa stars predicts embedded precursors only for short orbital period dwarf novae, therefore the presence of embedded precursors in long orbital period systems - U Gem and SS Cyg - argues for a more general mechanism to explain long outbursts.

VizieR Online Data Catalog: AGB stars with GALEX observations (Montez+, 2017)

NASA Astrophysics Data System (ADS)

Montez, R.; Ramstedt, S.; Kastner, J. H.; Vlemmings, W.; Sanchez, E.

2018-01-01

Our sample of AGB stars is derived from numerous AGB samples found in the literature and was originally compiled by Ramstedt+ (2012A&A...543A.147R) to search for X-ray detections associated with AGB stars. The GALEX mission performed a two-band survey of the UV sky. Using a dichromatic beam splitter, GALEX simultaneously observed far-UV (FUV; λeff~1528Å; 1344-1786Å) and near-UV (NUV; λeff~2310Å; 1771-2831Å) in surveys with different depths. The spatial resolution is 4.3" in FUV and 5.3" in NUV. As described in further detail in Morrissey+ (2007ApJS..173..682M), spectroscopic observations place a grism into the converging beam of the telescope to simultaneously disperse all sources onto the detector plane. According to Morrissey+ (2007), the usable ranges of the grism spectra are 1300-1820Å and 1820-3000Å in the FUV and NUV, with average resolutions of 8Å and 20Å, respectively. To supplement our study of the GALEX observations of AGB stars, we collected photometric data from across the electromagnetic spectrum for all the AGB stars considered using SIMBAD and VizieR tools. We aslo collected AAVSO light curves that span the GALEX mission lifetime (2003 May 28 to 2013 June 28) from the AAVSO International Database. (3 data files).

Nova Delphini 2013: Backyard Analysis of a Classical Nova

NASA Astrophysics Data System (ADS)

Reid, Piper

2014-01-01

On August 14, 2013, Nova Delphini was discovered by Koichi Itagaki. This nova erupted to a maximum brightness of magnitude 4.4 by August 16, 2013. The extraordinary brightness of this event has allowed many amateur astronomers to have the chance to study it. More than 750 amateur astronomers have contributed to the AAVSO photometry database of Nova Delphini.1 The amount and quality of spectroscopic data gathered is unprecedented as well, as over 700 individual spectra have been collected so far in the ARAS database.2 A nova is a class of variable star that undergoes a cataclysmic eruption, which can be observed through a sudden increase in brightness that declines over a series of months or years. At the center of a nova is an accreting white dwarf star which is collecting hydrogen from its surroundings. The accreting mass causes a nuclear reaction on the surface of the white dwarf and as the pressure increases the reaction becomes super-critical and a thermonuclear runaway is ignited causing the brightness increase as well as triggering the ejection of a shell of material form the star. The stages of a classical nova outburst are outlined along with techniques available to amateur astronomers for study of these phenomena. The author’s equipment and software setup are detailed. Results obtained using a low resolution grating, Schmidt-cassegrain telescope and CCD camera that were acquired while Nova Delphini was in the “fireball stage” 3 and subsequent “iron curtain phase”3 are compared and discussed. Results obtained using a high resolution spectroscope, Schmidt-cassegrain telescope and CCD camera that were acquired during the “lifting of the iron curtain phase”3 are also presented. References 1. Turner, Rebecca. “AAVSO - Nova Del 2013” 20 Aug 2013 Web. 8 Sep 2013 2. Tessier, Francois. “ARAS Spectral Database - Nova-Del-2013” 22 Sep 2013 Web. 22 Sep 2013 3. Shore, Steven N. “Spectroscopy of Novae - A User’s Manual” arXiv:1211.3176 [astro-ph.SR] 14 Nov 2012

British variable star associations, 1848-1908

NASA Astrophysics Data System (ADS)

Toone, J.

2010-06-01

The study of variable stars lagged some distance behind solar system, positional (double star) and deep sky research until the middle part of the 19th century. Then, following F. W. A. Argelander's pioneering work in the 1840s, there was a striking increase in variable star research, particularly in Europe. The transformation was to such an extent that in the second half of the 19th century there were three attempts at forming variable star associations within Great Britain. The first in 1863 was the ASOVS, which never got off the ground. The second in 1883 was the LAS VSS, which was successfully launched but had somewhat limited achievements. The third launched in 1890 was the BAA VSS which was eventually both a resounding and lasting success. This paper is an outline history of these three associations up to a position of one hundred years ago (1908). [A summary version of this paper was presented at the joint meeting of the American Association of Variable Star Observers (AAVSO) and British Astronomical Association Variable Star Section (BAA VSS) held at Cambridge, UK, on 2008 April 11.

Imaging Variable Stars with HST

NASA Astrophysics Data System (ADS)

Karovska, Margarita

2011-05-01

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 will 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 will describe the scientific results from the imaging observations of variable stars including AGBs, Miras, Cepheids, semi-regular 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.

Imaging Variable Stars with HST

NASA Astrophysics Data System (ADS)

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.

Atlas of the Light Curves and Phase Plane Portraits of Selected Long-Period Variables

NASA Astrophysics Data System (ADS)

Kudashkina, L. S.; Andronov, I. L.

2017-12-01

For a group of the Mira-type stars, semi-regular variables and some RV Tau - type stars the limit cycles were computed and plotted using the phase plane diagrams. As generalized coordinates x and x', we have used φ - the brightness of the star and its phase derivative. We have used mean phase light curves using observations of various authors from the databases of AAVSO, AFOEV, VSOLJ, ASAS and approximated using a trigonometric polynomial of statistically optimal degree. For a simple sine-like light curve, the limit cycle is a simple ellipse. In a case of more complicated light curve, in which harmonics are statistically significant, the limit cycle has deviations from the ellipse. In an addition to a classical analysis, we use the error estimates of the smoothing function and its derivative to constrain an "error corridor" in the phase plane.

Converting Differential Photometry Results to the Standard System using Transform Generator and Transform Applier (Abstract)

NASA Astrophysics Data System (ADS)

Ciocca, M.

2016-12-01

(Abstract only) Since Fall of 2014, AAVSO made available two very useful software tools: transform generator (tg) and transform applier (ta). tg, authored by Gordon Myers (gordonmyers@hotmail.com), is a program, running under python that allows the user to obtain the transformation coefficients of their imaging train. ta, authored by George Silvis, allows users to apply the transformation coefficients obtained previously to their photometric observation. The data so processed become then directly comparable to those of other observers. I will show how to obtain transform coefficient using two Standard Field (M 67 and NGC7790), how consistent the results are and as an application, I will present transformed data for two AAVSO Target stars, AE UMA and RR CET.

Obituary: Franklin Kamney (1925-2011)

NASA Astrophysics Data System (ADS)

Kinne, Richard

2011-12-01

Dr. Franklin E. Kameny died October 11, 2011, at the age of 86 of cardiac arrest. Kameny observed RV Tau stars and yellow semiregular variables from 1952 to1954, and his photoelectric measurements served as the basis of his Harvard Ph.D. thesis. After receiving his Ph.D. in 1956, Kameny taught astronomy for a year at Georgetown University. A US Army veteran during World War II, he was hired as an astronomer by the US Army Mapping Service in 1957. His astronomical career was terminated when he was fired from this position due to the discovery of his sexual orientation. Denied his first occupation as an astronomer, Kameny became a pioneer in the struggle for equal rights and was involved in many issues leading to just and equitable treatment of all people. One of his most most notable achievements was working for the removal of homosexuality from the American Psychiatric Association's manual of mental disorders. One of his most recent achievements was helping to push through the Washington, DC, marriage equality act. After a lonely 40-year struggle, Kameny recently began to receive recognition for all his work. In June of 2009, the Office of Personnel Management formally apologized for Kameny's firing and issued him their highest award. The apology letter, in Kameny's estimation, left open the possibility he'd never actually been fired. In his acceptance of the apology he sent the Office a letter, tongue-in-cheek, requesting that the Office let him know what his back pay was! Kameny was present in the Oval Office for the signing of the repeal of "Don't Ask, Don't Tell" in 2010 and was thanked for his work by both President Obama and Vice President Biden. 17th Street in Washington, DC, between P and R Streets was named "Frank Kameny Way," and Kameny's house is now listed on the National Register of Historic Places. Kameny's astronomical career, as short as it may have been, has not been forgotten. In the summer of 2009, his dissertation was "rediscovered" by AAVSO staff in the McAteer Library and his data - 547 observations of RV Tau type stars and other semiregular yellow variables - were added to the AAVSO International Database. Often these are the only observations of these variables on record during this time period. Kameny's unflagging determination in the face of adversity has also served as inspiration over the last year for Society members organizing the new AAS Working Group on LGBTQ Equality. The Society will award a posthumous certificate of appreciation to Dr. Kameny at the January 2012 meeting in Austin, TX. Denied his place in the scientific community by the social conventions of the day, Dr. Kameny fought back and thereby made the world a more equal place. In that way he remains a star in his own right.

Multicolor Observations of ASAS 002511+1217.2

NASA Astrophysics Data System (ADS)

Golovin, Alex; Price, Aaron; Templeton, Matthew; Cook, Lewis; Crawford, Timothy; Henden, Arne; James, Robert; Koppelman, Michael; Nelson, Peter Robert; Oksanen, Arto; Pavlenko, Elena; Pickard, Roger; Quinn, Nick; Starkey, Don Ray

2005-04-01

ASAS 002511+1217.2 is a newly discovered cataclysmic variable in Pisces constellation. It was discovered by G. Pojmanski and the ASAS-3 survey on 11.203 (UT) Sept., 2004. The new variable is within the uncertainly boundaries of RX J0025.1+1217, 1RXS J002510.8+121725, 2MASS J00251111+1217121. The AAVSO has collected 31839 CCD observations of ASAS 002511+1217.2 over a 55 day period following its outburst. This is CCD-lightcurve, based on our observations. The errors depend on the observer, but typically can be estimated to be +/- 0.02 for CCD observations. It is interesting to note that so-called an echo-outburst occurred, reaching a maximum at 20 days after super-outburst' maximum. Before combining data for statistical analysis, each observer's data set was individually transformed to an uniform zero-point by subtracting a linear fit from each night's observations. This was done so that we could remove the overall trend of outburst, and to combine all observations into a single data set. The analysis of CCD observations by the Lalfer-Kinman method has enabled us to show the presence of the 0.05701 period of superhumps. The periodogram presents the peak, which corresponds to the mentioned period. This figure shows an example superhump phase diagram with the estimated period. As an example of the superhump profile, we plotted on the phase diagram the superhumps, observed on 20 Sept., by Elena Pavlenko at the Crimean Astrophysical Observatory. The results of this observing-campaign were recently published at 4th of March in Informational Bulletin on Variable Stars of the International Astronomical Union at 5611 issue.

The Pan-STARRS 1 Medium Deep Field Variable Star Catalog

NASA Astrophysics Data System (ADS)

Flewelling, Heather

2016-01-01

We present the first Pan-STARRS 1 Medium Deep Field Variable Star Catalog (PS1-MDF-VSC). The Pan-STARRS 1 (PS1) telescope is a 1.8 meter survey telescope with a 1.4 Gigapixel camera, located in Haleakala, Hawaii. The Medium Deep survey, which consists of 10 fields located uniformly across the sky, totaling 70 square degrees, is observed each night, in 2-3 filters per field, with 8 exposures per filter, resulting in 3000-4000 data points per star over a time span of 3.5 years. To find the variables, we select objects with > 200 detections, and remove those flagged as saturated. No other cuts are used. There are approximately 2.4 million objects that fit this criteria, with magnitudes between 13th and 24th. These objects are then passed through a lomb-scargle fitting routine to determine periodicity. After a periodicity cut, the candidates are classified by eye into different types of variable stars. We have identified several thousand periodic variable stars, with periods ranging between a few minutes to a few days. We compare our findings to the variable star catalogs within Vizier and AAVSO. In particular, for field MD02, we recover all the variables that are faint in Vizier, and we find good agreement with the periods reported in Vizier.

Caroline Furness and the Evolution of Visual Variable Star Observing

NASA Astrophysics Data System (ADS)

Larsen, Kristine

2017-01-01

An Introduction to the Study of Variable Stars by Dr. Caroline Ellen Furness (1869-1936), Director of the Vassar College Observatory, was published in October 2015. Issued in honor of the fiftieth anniversary of the founding of Vassar College, the work was meant to fill a void in the literature, namely as both an introduction to the topic of variable stars as well as a manual explaining how they should be observed and the resulting data analyzed. It was judged to be one of the hundred best books written by an American woman in the last hundred years at the 1933 World’s Fair in Chicago. The book covers the relevant history of and background on types of variable stars, star charts, catalogs, and the magnitude scale, then describes observing techniques, including visual, photographic, and photoelectric photometry. The work finishes with a discussion of light curves and patterns of variability, with a special emphasis on eclipsing binaries and long period variables. Furness’s work is therefore a valuable snapshot of the state of astronomical knowledge, technology, and observing techniques from a century ago. Furness’s book and its reception in the scientific community are analyzed, and parallels with (and departures from) the current advice given by the AAVSO to beginning variable star observers today are highlighted.

Sunlight in the Spotlight in the International Year of Light (Poster abstract)

NASA Astrophysics Data System (ADS)

Larsen, K.

2015-12-01

(Abstract only) One of the main focuses of the International Year of Light (IYL) is interdisciplinary education and outreach. While variable stars in general provide myriad opportunities to accomplish this, one variable star in particular—our sun—offers unique opportunities in this vein. From conducting ground-based safe solar observations with white light and hydrogen alpha filters, to highlighting satellite observations at other wavelengths and spectroscopy, observing our nearest star provides a solid basis from which to explore the electromagnetic spectrum (and the relevant technologies used to study it). The IYL highlights cultural astronomy, the history of science, and the important role women have played in our understanding of the natural world. Not only was the primary deity in many cultures the sun god or goddess, but the motions of the sun across the heavens were carefully studied using sundials, astrolabes, and monolithic structures (including Stonehenge). Sunspots were discovered long before the invention of the telescope, and their occurrences carefully recorded. Today, these records (along with records of another important way the sun interacts with our planet, namely the creation of aurora) extend our understanding of the solar cycle backwards in time across the centuries to before the time of Galileo. Women have played an important role in our observation and understanding of the sun, including Annie Maunder at the Royal Greenwich Observatory and Elizabeth Brown, Solar Section Director of the British Astronomical Association. The sun also played a central role in verifying Einstein's General Theory of Relativity (itself celebrating its centenary during the IYL). This poster will provide examples of sun-centered projects and activities that can be used during the IYL and beyond to educate and interest citizens young and old about our nearest star, with an eye to especially highlighting the importance of the ongoing work of the Solar Section of the AAVSO.

Campaign for a New Eclipsing Cepheid

NASA Astrophysics Data System (ADS)

Henden, Arne; Welch, Doug; Terrell, Dirk

2007-06-01

ASAS 182611+1212.6, discovered by Pojmanski et al. during the ASAS survey, independently discovered by Antipin at al. on Moscow archive plates, and found in the NSVS (Wozniak et al. 2004, AJ 127, 2436), was initially classified as a typical Type II Cepheid with a period of 4.1523 days. However, scatter in the light curve indicated possible multiperiodic behavior. After 3 years of CCD observations by Antipin, the system was seen to exhibit eclipses of period 51.38 days and amplitude about 0.3 mag (primary) and possibly about 0.2 mag (secondary). This is the first known glactic eclipsing binary Cepheid. The AAVSO is conducting a campaign to study this star via high-precision, multicolor photometry obtained over several eclipse cycles. Observers are requested to obtain multicolor photometry with a S/N=100 or better on every image. Time resolution of one hour is adequate, so cycling through the filters need not be rushed. Apply transformation coefficients when possible. For calculating ephemerides, the pulsational maximum occurred on HJD 2453196.529 with a period of 4.1523 days; the eclipse primary minimum occurred on HJD 2453571.36 with a period of 51.38 days. The next primary eclipse will occur around July 9, but these eclipses are several days wide. A finding chart may be found at http://www.aavso.org/observing/charts/vsp (enter ASAS182612 for its name, or use the coordinates) with suitable comparison stars marked. Report/upload observations to the AAVSO.

Monitoring HD 148703 during upcoming eclipses

NASA Astrophysics Data System (ADS)

Waagen, Elizabeth O.

2017-06-01

Dr. Milena Ratajczak (University of Wrocław) has requested AAVSO observers' assistance in monitoring the very bright (V = 4.23) and very unusual eclipsing binary HD 148703 (HR 6143, N Sco) during its infrequent primary and secondary eclipses scheduled for 2017 June 11 and June 14, respectively. Dr. Ratajczak writes: "[HD 148703] N Sco is a B-type detached eclipsing binary, which turned out to be an exceptionally interesting object to study when we realised its orbital period is 223 days and time between eclipses is only 3.5 days. Such configuration makes it an extremely eccentric system, probably the most eccentric from any objects of that class ever studied...Since the object is very bright, it's difficult to use professional photometric telescopes due to saturation issues. That is why we kindly invite amateur astronomers to join the campaign. Data taken during times of eclipses (photometry) and time between eclipses (radial velocities from spectroscopy) which occur next week are crucial to cover in order to determine orbital and stellar parameters of system's components. Data taken over that time will be of very high value for us." The next primary eclipse time of minimum is on 2017 June 11 (UT 00:41:45), and the secondary on June 14 (UT 09:17:34). Each eclipse lasts about 20 hours. The amplitude of the primary eclipse is 0.15 magnitude, and the secondary 0.35 mag. PEP V and DSLR V photometry is requested. (CCD V is welcome if saturation can be avoided.) Beginning immediately, one to a few snapshots each night are requested to establish an out-of-eclipse baseline for each observer; they should continue for a few nights after the secondary eclipse has occurred.Time series photometry is requested beginning 12 hours before each time of minimum and continuing until 12 hours after. Precision to 0.01 mag or better per single observation is needed. Exposures should be as long as possible without saturating; don't make very short exposures simply for the purpose of gathering more data points. B or Ic data would also be useful; B is preferred to Ic. If imaging in more than one filter, please make five V observations for each B or Ic.Visual observations are also welcome. For spectroscopy now through June 20, resolution of at least a few thousands is needed. Coordinates: RA = 16 31 22.93 Dec = -34 42 15.7 (2000.0). Finder charts may be created and data from the AAVSO International Database may be viewed, plotted, or downloaded (www.aavso.org).

AAVSO Visual Sunspot Observations vs. SDO HMI Sunspot Catalog

NASA Astrophysics Data System (ADS)

Howe, R.

2014-06-01

(Abstract only) The most important issue with regard to using the SDO HMI data from the National Solar Observatory (NSO, http://www.nso.edu/staff/fwatson/STARA) is that their current model for creating sunspot counts does not split in groups and consequently does not provide a corresponding group count and Wolf number. As it is a different quantity, it cannot be mixed with the data from our sunspot networks. For the AAVSO with about seventy stations contributing each day, adding HMI sunspot data would anyway hardly change the resulting index. Perhaps, the best use of HMI data is for an external validation, by exploiting the fact that HMI provides a series that is rather close to the sunspot number and is acquired completely independently. So, it is unlikely to suffer from the same problems (jumps, biases) at the same time. This validation only works for rather short durations, as the lifetime of space instruments is limited and aging effects are often affecting the data over the mission. In addition, successive instruments have different properties: for example, the NSO model has not managed yet to reconcile the series from MDI and HMI. There is a ~10-15% jump. The first challenge that should be addressed by AAVSO using HMI data is the splitting in groups and deriving group properties. Then, together with the sunspot counts and areas per group, a lot more analyses and diagnostics can be derived (like the selective disappearance of the smallest sunspots?), that can help interpreting trends in the ratio SSN/other solar indices and many other solar effects.

A Method for Transferring Photoelectric Photometry Data from Apple II+ to IBM PC

NASA Astrophysics Data System (ADS)

Powell, Harry D.; Miller, James R.; Stephenson, Kipp

1989-06-01

A method is presented for transferring photoelectric photometry data files from an Apple II computer to an IBM PC computer in a form which is compatible with the AAVSO Photoelectric Photometry data collection process.

Recent Minima of 171 Eclipsing Binary Stars

NASA Astrophysics Data System (ADS)

Samolyk, G.

2015-12-01

This paper continues the publication of times of minima for 171 eclipsing binary stars from observations reported to the AAVSO EB section. Times of minima from observations received by the author from March 2015 thru October 2015 are presented.

The inter-outburst behavior of cataclysmic variables

NASA Technical Reports Server (NTRS)

Szkody, Paula; Mattei, Janet A.; Waagen, Elizabeth O.; Stablein, Clay

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.

VizieR Online Data Catalog: Period-mass-loss rate relation of Miras (Uttenthaler, 2013)

NASA Astrophysics Data System (ADS)

Uttenthaler, S.

2013-06-01

Table 1 is a collection of information on the technetium (Tc) content, pulsation period, and IR photometry of AGB variables, without claim of completeness, in particular for the semi-regular variables (SRVs). Up to three references on the Tc content are given. The pulsation period is the most up-to-date value possible, for many objects based on an analysis of AAVSO data with the Period04 program (Lenz & Breger, 2005CoAst.146...53L). The spectral (or chemical) type of the star is taken from the same literature as the information on Tc. A mean K magnitude and J-K colour is computed from all available literature, as listed in Sect. 2 of the paper; they are meant to be as close as possible to cycle-averaged values, to average out the variability of the objects. Finally, magnitudes are given in the IRAS 12, 25, and 60 micron bands, Akari 9 and 18 micron bands, and WISE 22 micron bands are given, where fluxes have been converted to magnitudes given the zero-magnitude fluxes as given in the Note to Table 1. (1 data file).

Parallel Group and Sunspot Counts from SDO/HMI and AAVSO Visual Observers (Abstract)

NASA Astrophysics Data System (ADS)

Howe, R.; Alvestad, J.

2015-06-01

(Abstract only) Creating group and sunspot counts from the SDO/HMI detector on the Solar Dynamics Observatory (SDO) satellite requires software that calculates sunspots from a “white light” intensity-gram (CCD image) and group counts from a filtered CCD magneto-gram. Images from the satellite come from here http://jsoc.stanford.edu/data/hmi/images/latest/ Together these two sets of images can be used to estimate the Wolf number as W = (10g + s), which is used to calculate the American Relative index. AAVSO now has approximately two years of group and sunspot counts in the SunEntry database as SDOH observer Jan Alvestad. It is important that we compare these satellite CCD image data with our visual observer daily submissions to determine if the SDO/HMI data should be included in calculating the American Relative index. These satellite data are continuous observations with excellent seeing. This contrasts with “snapshot” earth-based observations with mixed seeing. The SDO/HIM group and sunspot counts could be considered unbiased, except that they show a not normal statistical distribution when compared to the overall visual observations, which show a Poisson distribution. One challenge that should be addressed by AAVSO using these SDO/HMI data is the splitting of groups and deriving group properties from the magneto-grams. The filtered CCD detector that creates the magento-grams is not something our visual observers can relate too, unless they were to take CCD images in H-alpha and/or the Calcium spectrum line. So, questions remain as to how these satellite CCD image counts can be integrated into the overall American Relative index.

Minimum-Light Spectral Classifications for M-Type Mira Variables

NASA Astrophysics Data System (ADS)

Wing, Robert F.

2015-08-01

Many bright, well-known Mira variables, including most of the 378 stars for which the AAVSO publishes predicted dates of maximum and minimum in its annual Bulletins, have never been spectroscopically observed close to the time of minimum light, and consequently their catalogued ranges in spectral type are often grossly and misleadingly under-represented. In an effort to improve this situation, for the past 12 years I have been using my 6-color system of narrow-band classification photometry to observe Miras predicted to be near minimum light at the times of my biannual observing runs with the CTIO 0.9-m telescope (operated by the SMARTS consortium). The 6-color system measures the 7100 A band of TiO, which serves to classify stars in the interval K4 to M8, and the 1.06 micron band of VO, which is effective for stars of type M8 and later. To date I have made 431 observations of approximately 220 different (and mostly southern) Miras. Examples are shown of the observed 6-color spectra, and the classifications derived from them.

Campaign of AAVSO Monitoring of the CH Cyg Symbiotic System in Support of Chandra and HST Observations

NASA Astrophysics Data System (ADS)

Karovska, M.

2013-06-01

(Abstract only) CH Cyg is one of the most interesting interacting binaries in which a compact object, a white dwarf or a neutron star, accretes from the wind of an evolved giant or supergiant. CH Cyg is a member of the symbiotic systems group, and at about 250pc it is one of the closest systems. Symbiotic systems are accreting binaries, which are likely progenitors of a fraction of Pre-Planetary and Planetary Nebulae, and of a fraction of SN type Ia (the cosmic distance scale indicators). We carried out Chandra and HST observations of CH Cyg in March 2012 as part of a follow-up investigation of the central region of CH Cyg and its precessing jet, including the multi-structures that were discovered in 2008. I will describe here the campaign of multi-wavelength observations, including photometry and spectroscopy, that were carried out by AAVSO members in support of the space-based observations.

Goldilocks Variable - ein Mira-Stern im Hantelnebel M 27

NASA Astrophysics Data System (ADS)

Breitenstein, Paul; Beer, Fabian; Broering, Lukas; Wortmann, Marco

2016-02-01

We recorded very densely nearly 2,5 periods of brightness of the Mira star NSV 24959, called "Goldilocks", in the star field of the Dumbbell Nebula M27 with the 1,2m MONET-North-Telescope (briefly: MONET-North) and the 14' Bradford Robotic Telescope (briefly: BRT). Also we tested all archive images of M27, which were made between 2007 until now with the BRT, for evaluable changes of light of NSV 24959 and analyzed them. Furthermore we got curves of brightness of NSV 24959 of the years 1997 to 2000 from Arne Henden, former director of AAVSO [1]. By reason of the longe time basis of the observation from 1997 till 2015 the middle periodic time could be fixed at 214 days by a maximal error of one day. Thereby the changes of lightness seems to be relativ constant in this 18 years. Only in two periods we saw an extraordinary strong increase of lightness.

Brightness Variations in the Central Star of Eta Carinae From 1998 to the Present

NASA Technical Reports Server (NTRS)

Martin, J. C.; Koppelman, M. D.

2004-01-01

Recently, Eta Carinae has varied suprisingly in brightness combining a long term brightening trend with a 5.5-year cycle and unpredictable sporadic jumps. Only the Hubble Space Telescope had been able to provide reliable photometry of the central star resolved separately from its bright ejecta. We present data from the Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) and the Advanced Camera for Surveys High Resolution Camera (ACS/HRC) which chronicle the dramatic brightening of the central star of Eta Carinae from the 1998 "event" through 2000 and show that is has continued to slowly brighten. More frequent photometry during its recent "event" and a continued rise afterward. These data are compared to the more long term data compiled by the American Association of Variable Star Observers (AAVSO) which also shows substantial brightening between events and other intervening fluctuations in the brightness of Eta Carinae at visual wavelengths.

Nova Mus 2008 = QY Mus

NASA Astrophysics Data System (ADS)

Templeton, Matthew R.

2008-10-01

Nova Mus 2008 = QY Mus was discovered by William Liller, Vina del Mar, Chile, on 2008 September 28.998 UT at magnitude 8.6 (Tech Pan film + orange filter). The position is RA = 13h 16m 36.44s , Dec = -67d 36m 47.8s (from P. Nelson). This object was announced as a nova in IAU Circular 8990 (Daniel W.E. Green, editor). The nova classification was determined using low-resolution spectra by W. Liller indicating the presence of broad H-alpha lines at least 2300 angstroms wide. Several observers confirmed the nova and provided photometry. The position above was provided by Peter Nelson (Ellinbank, Vic., Aus.), and is averaged from four separate exposures (rms error approx. 0.4 arcseconds). The GCVS team have formally designated Nova Mus 2008 as QY MUS. Observations should be reported to the AAVSO International Database as QY MUS.

As International as They Would Let Us Be

NASA Astrophysics Data System (ADS)

Trimble, V.

2015-08-01

Astronomy has always crossed borders, continents, and oceans. AAVSO itself has roughly half its membership residing outside the USA. In this excessively long paper, I look briefly at ancient and medieval beginnings and more extensively at the 18th and 19th centuries, plunge into the tragedies associated with World War I, and then try to say something relatively cheerful about subsequent events. Most of the people mentioned here you will have heard of before (Eratosthenes, Copernicus, Kepler, Olbers, Lockyer, Eddington…) others, just as important, perhaps not (von Zach, Gould, Argelander, Freundlich…). Division into heroes and villains is neither necessary nor possible, though some of the stories are tragic. In the end, all one can really say about astronomers' efforts to keep open channels of communication that others wanted to choke off is, "the best we can do is the best we can do."

Maxima and O-C Diagrams for 489 Mira Stars

NASA Astrophysics Data System (ADS)

Karlsson, T.

2013-11-01

Maxima for 489 Mira stars have been compiled. They were computed with data from AAVSO, AFOEV, VSOLJ, and BAA-VSS and collected from published maxima. The result is presented in a mysql database and on web pages with O-C diagrams, periods and some statistical information for each star.

Variability Properties of Four Million Sources in the TESS Input Catalog Observed with the Kilodegree Extremely Little Telescope Survey

NASA Astrophysics Data System (ADS)

Oelkers, Ryan J.; Rodriguez, Joseph E.; Stassun, Keivan G.; Pepper, Joshua; Somers, Garrett; Kafka, Stella; Stevens, Daniel J.; Beatty, Thomas G.; Siverd, Robert J.; Lund, Michael B.; Kuhn, Rudolf B.; James, David; Gaudi, B. Scott

2018-01-01

The Kilodegree Extremely Little Telescope (KELT) has been surveying more than 70% of the celestial sphere for nearly a decade. While the primary science goal of the survey is the discovery of transiting, large-radii planets around bright host stars, the survey has collected more than 106 images, with a typical cadence between 10–30 minutes, for more than four million sources with apparent visual magnitudes in the approximate range 7< V< 13. Here, we provide a catalog of 52,741 objects showing significant large-amplitude fluctuations likely caused by stellar variability, as well as 62,229 objects identified with likely stellar rotation periods. The detected variability ranges in rms-amplitude from ∼3 mmag to ∼2.3 mag, and the detected periods range from ∼0.1 to ≳2000 days. We provide variability upper limits for all other ∼4,000,000 sources. These upper limits are principally a function of stellar brightness, but we achieve typical 1σ sensitivity on 30 min timescales down to ∼5 mmag at V∼ 8, and down to ∼43 mmag at V∼ 13. We have matched our catalog to the TESS Input catalog and the AAVSO Variable Star Index to precipitate the follow-up and classification of each source. The catalog is maintained as a living database on the Filtergraph visualization portal at the URL https://filtergraph.com/kelt_vars.

Flares, Fears, and Forecasts: Public Misconceptions About the Sunspot Cycle

NASA Astrophysics Data System (ADS)

Larsen, K.

2012-06-01

Among the disaster scenarios perpetrated by 2012 apocalypse aficionados is the destruction of humankind due to solar flares and coronal mass ejections (CMEs). These scenarios reflect common misconceptions regarding the solar cycle. This paper (based on an annual meeting poster) sheds light on those misconceptions and how the AAVSO Solar Section can address them.

Multi-color Photometry of the Hot R Coronae Borealis Star, MV Sagittarii

NASA Astrophysics Data System (ADS)

Landolt, A. U.; Clem, J. L.

2017-12-01

A long term program of photoelectric UBVRI photometry has been combined with AAVSO archival data for the hot, R CrB-type hydrogen deficient star MV Sgr. A deep minimum and a trend of decreasing brightness over time at maximum light thereby become evident. Variations seen via monitoring with a CCD detector also are described.

Pulsation Properties of Carbon and Oxygen Red Giants

NASA Astrophysics Data System (ADS)

Percy, J. R.; Huang, D. J.

2015-07-01

We have used up to 12 decades of AAVSO visual observations, and the AAVSO VSTAR software package to determine new and/or improved periods of 5 pulsating biperiodic carbon (C-type) red giants, and 12 pulsating biperiodic oxygen (M-type) red giants. We have also determined improved periods for 43 additional C-type red giants, in part to search for more biperiodic C-type stars, and also for 46 M-type red giants. For a small sample of the biperiodic C-type and M-type stars, we have used wavelet analysis to determine the time scales of the cycles of amplitude increase and decrease. The C-type and M-type stars do not differ significantly in their period ratios (first overtone to fundamental). There is a marginal difference in the lengths of their amplitude cycles. The most important result of this study is that, because of the semiregularity of these stars, and the presence of alias, harmonic, and spurious periods, the periods which we and others derive for these stars—especially the smaller-amplitude ones—must be determined and interpreted with great care and caution. For instance: spurious periods of a year can produce an apparent excess of stars, at that period, in the period distribution.

Monitoring of Mira (omi Cet) in support of HST Observations

NASA Astrophysics Data System (ADS)

Karovska, Margarita; Templeton, Matthew R.

2007-09-01

Dr. Margarita Karovska (Harvard-Smithsonian Center for Astrophysics) and collaborators are performing a comprehensive study of the Mira AB interacting system, using the HST WFPC2 camera. Mira AB is composed of the prototype Mira variable omi Cet and its companion VZ Cet, separated by about 0.5 arcsecond. As part of this project they plan to obtain a large number of high-angular resolution images at wavelengths ranging from UV to optical. The main objectives of the HST/WFPC2 observations are 1) to determine the properties of the material ejected in December 2004 as it flows throughout the binary and interacts with the Mira A (omi Cet, Mira) circumstellar material and wind; 2) to determine the physical characteristics of mass transfer in this system and especially the role of the accretion stream between Mira A and its accreting companion Mira B (VZ Cet); 3) to determine the response of the system to the increased accretion rate onto Mira B following the outburst. The HST observations are scheduled for September 23, 1900-2300 UT. Both visual and instrumental observers are requested to observe this object, currently at minimum around visual magnitude 9-9.5. Observations should be made approximately two weeks on either side of the September 23 observation date. Visual observer should observe as usual, making not more than 3 observations spaced about 10 days apart. PEP and CCD observers should use the bluest-wavelength filters they have, and should make nightly observations, with intensive observations during the HST observations themselves. UBV and RIJH observations would be very valuable. Please make sure to use an aperture that covers both omi Cet and VZ Cet when evaluating CCD images. Observations should be submitted to the AAVSO International Database as OMI CET.

Variable Stars and Constant Commitments: The Stellar Career of Dorrit Hoffleit

NASA Astrophysics Data System (ADS)

Larsen, Kristine

2011-05-01

Astronomer, educator, and science historian Dorrit Hoffleit (1907-2007) was widely respected by the amateur and professional astronomical community as a mentor and an ardent supporter of independent research. Her more than 600 catalogues, books, articles, book reviews, and news columns cover myriad aspects of astronomy, from variable stars and stellar properties to meteor showers, quasars, and rocketry. She also made important contributions to the history of astronomy. Hoffleit worked at the Harvard College Observatory from 1927-1956, where she discovered over 1200 variable stars. When Director Harlow Shapley retired from Harvard, Hoffleit gave up her tenured position and moved to Yale University, where she was placed in charge of the Yale Catalog of Bright Stars. At the same time, she was offered a position as director of the Maria Mitchell Observatory on Nantucket Island in Massachusetts. Hoffleit split her dual positions into six-month stints and remained director at the Mitchell Observatory for 21 years, developing a summer research program that engaged more than 100 undergraduate students (all but three of them women) in variable star research. Up until shortly before her death, she continued to work tirelessly on selected projects, and she was in high demand as a collaborator with colleagues at Yale and elsewhere. She was especially devoted to the American Association of Variable Star Observers (AAVSO) in part because it brought together amateur and professional astronomers in collaboration. She served on the organization's council for 23 years and as its president from 1961-1963. In 2002, the AAVS0 published her autobiography, Misfortunes as Blessings in Disguise, in which Hoffleit explains how she always felt blessed by the opportunities in her life, even those which initially seemed misfortunes, and above all else valued creativity, flexibility, collegiality, and intellectual freedom in her professional life.

The 2006-2007 Observing Campaign On VX Hydrae

NASA Astrophysics Data System (ADS)

Templeton, Matthew R.; Samolyk, G.; Dvorak, S.; Poklar, R.; Butterworth, N.; Gerner, H. S.

2009-12-01

We present the results of the 2006-2007 observing campaign on the double-mode delta Scuti star VX Hydrae. Nearly 8800 V-band CCD observations were obtained during the two observing seasons. Although the data were taken with small telescopes (0.3-m or less, using consumer-grade CCD cameras), the data quality is very high, enabling the detection of variability at the millimagnitude level at some frequencies. Analysis of the data yields only two primary pulsation frequencies: f(0) = 4.4765 c/d, and f(1) = 5.7899 c/d. The two modes have comparable amplitude, although the amplitude of f(1) appears to have increased slightly from 2006 to 2007 by 0.01 mag. Only two pulsation modes are detected, but at least 18 additional linear combination frequencies are also clearly detected, some having amplitudes as low as 1 mmag, resulting in an incredibly rich Fourier spectrum. We discuss the evidence for amplitude variation in VX Hydrae, along with prospects for future study of this and other similar delta Scuti stars by AAVSO observers.

Multiple Stellar Flybys Sculpting the Circumstellar Architecture in RW Aurigae

NASA Astrophysics Data System (ADS)

Rodriguez, Joseph E.; Loomis, Ryan; Cabrit, Sylvie; Haworth, Thomas J.; Facchini, Stefano; Dougados, Catherine; Booth, Richard A.; Jensen, Eric L. N.; Clarke, Cathie J.; Stassun, Keivan G.; Dent, William R. F.; Pety, Jérôme

2018-06-01

We present high-resolution ALMA Band 6 and 7 observations of the tidally disrupted protoplanetary disks of the RW Aurigae binary. Our observations reveal tidal streams in addition to the previously observed tidal arm around RW Aur A. The observed configuration of tidal streams surrounding RW Aur A and B is incompatible with a single star–disk tidal encounter, suggesting that the RW Aurigae system has undergone multiple flyby interactions. We also resolve the circumstellar disks around RW Aur A and B, with CO radii of 58 au and 38 au consistent with tidal truncation, and 2.5 times smaller dust emission radii. The disks appear misaligned by 12° or 57°. Using new photometric observations from the American Association of Variable Star Observers (AAVSO) and the All Sky Automated Survey for SuperNovae (ASAS-SN) archives, we have also identified an additional dimming event of the primary that began in late 2017 and is currently ongoing. With over a century of photometric observations, we are beginning to explore the same spatial scales as ALMA.

An Overview of the AAVSO's Information Technology Infrastructure From 1967 to 1997

NASA Astrophysics Data System (ADS)

Kinne, R. C. S.

2012-06-01

Computer technology and data processing swept both society and the sciences like a wave in the latter half of the 20th century. We trace the AAVSO’s usage of computational and data processing technology from its beginnings in 1967, through 1997. We focus on equipment, people, and the purpose such computational power was put to, and compare and contrast the organization’s use of hardware and software with that of the wider industry.

Detection of U Sco in X-rays

NASA Astrophysics Data System (ADS)

Schlegel, Eric M.; Schaefer, Brad; Pagnotta, Ashley; Page, Kim; Osborne, Julian; Drake, Jeremy; Orio, Marina; Takei, Dai; Kuulkers, Erik; Ness, Jan-Uwe

2010-02-01

Eric M. Schlegel (UT-San Antonio); Brad Schaefer and Ashley Pagnotta (LSU); Kim Page and Julian Osborne (Leicester); Jeremy Drake (SAO); Marina Orio (Wisconsin), Dai Takei (Rikkyo Univ.), and Erik Kuulkers and Jan-Uwe Ness (ESA/ESAC), representing a large collaboration, report that U Sco has been detected in the X-ray band using the Swift satellite following the optical outburst discovery at V=8.05 on 2010 January 28.4743 (www.aavso.org/publications/alerts/alert415.shtml).

AAVSO Solar Observers Worldwide

NASA Astrophysics Data System (ADS)

Howe, R.

2013-06-01

(Abstract only) For visual solar observers there has been no biological change in the "detector" (human eye) - at century scales (eye + visual cortex) does not change much over time. Our capacity to "integrate" seeing distortions is not just simple averaging! The visual cortex plays an essential role, and until recently only the SDO-HMI (Solar Dynamics Observatory, Helioseismic and Magnetic Imager) has had the capacity to detect the smallest sunspots, called pores. Prior to this the eye was superior to photography and CCD. Imaged data are not directly comparable or substitutable to counts by eye, as the effects of sensor/optical resolution and seeing will have a different influence on the resulting sunspot counts for images when compared to the human eye. Also contributing to the complex task of counting sunspots is differentiating between a sunspot (which is usually defined as having a darker center (umbra) and lighter outer ring (penumbra)) and a pore, made even more complex by the conflicting definitions of the word "pore" in the solar context: "pore" can mean a small spot without penumbra or "pore" can mean a random intergranular blemish that is not a true sunspot. The overall agreement is that the smallest spot size is near 2,000 km or ~3 arc sec, (Loughhead, R. E. and Bray, R. J. 1961, Australian J. Phys., 14, 347). Sunspot size is dictated by granulation dynamics rather than spot size (cancellation of convective motion), and by the lifetime of the pore, which averages from 10 to 30 minutes. There is no specific aperture required for AAVSO observers contributing sunspot observations. However, the detection of the smallest spots is influenced by the resolution of the telescope. Two factors to consider are the theoretical optical resolution (unobstructed aperture), Rayleigh criterion: theta = 138 / D(mm), and Dawes criterion: theta = 116 / D(mm) (http://www.telescope-optics.net/telescope_resolution.htm). However, seeing is variable with time; daytime range will be similar for all low-altitude sites, within the range of 1.5 to 3 arc sec, (typically = 2 arc sec equivalent diameter D = 45-90 mm, the typical solar scope = 70 mm aperture). Where large apertures are more affected by size of turbulent eddies ~8-12 cm, small-aperture telescopes reduce these differences, i.e. large aperture is not always beneficial.

UCAC4 Nearby Star Survey: A Search for Our Stellar Neighbors

DTIC Science & Technology

2014-12-01

AAVSO) Photometric All Sky Survey (APASS) and infrared photometry from the Two Micron All-Sky Survey ( 2MASS ). With the addition of the APASS...110 million have 2MASS JHKs. We used a 3 arcsecond match radius in the development of the UCAC4 catalog for inclusion of the 2MASS and APASS...a new set of 16 photometric color–MKs relations using (a) BVgri optical photometry from APASS, (b) JHKs near-infrared photometry from 2MASS , (c

The NP Draconii Multiple Star System

NASA Astrophysics Data System (ADS)

Castelaz, Michael W.; Barker, Thurburn; McNaughton, Abby; Robertson, Rachel; Smith, Matt

2016-01-01

Otero and Dubovsky used the ASAS-3 (Pojmanski 2002), Hipparcos (Perryman et al 1997) and Northern Sky Variability Survey (NSVS; Wozniak et al 2004) databases to determine elements for 80 eclipsing binaries. NP Draconii (NSV 22984) was identified by Otero and Dubovsky (IBVS Number 5557, 2004) as a possible Algol type variable with an ephemeris of HJD Min I = 2448604.780+3.10886E days based on 84 observations over 326 days with about 2 to 4 observations on any one night. We decided to further refine the ephemeris and observe NP Dra in VRI filters, with the goal of determining the elements of the system.NP Dra is a V = 9.0 system located at J2000 = 17h 35m 16s and +55d 00' 12". We observed NP Dra August 2, 3 and September 15, 16, 17, 18, and 19 2015 UT using the Pisgah Astronomical Research Institute 0.4-m telescope in V, R, and I with 20 second exposure times in each filter. Observations in each filter were repeated about every 3 minutes each night of observing.From our light curves we determined the period using the Date Compensated Discrete Fourier Transform function (Ferraz-Mello 1981) which is part of the open source code VSTAR (AAVSO). The period derived from the observations is 2.2755 days. Superimposed on this period is another period of 0.6398 days. We will present the V, R, and I light curves, period determination and implication

LONG-TERM EVOLUTION OF THE MAIN-ON STATES IN HERCULES X-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Šimon, Vojtech, E-mail: simon@asu.cas.cz

2015-07-15

Rossi X-ray Timing Explorer All-sky Monitor (RXTE ASM) observations and American Association of Variable Star Observers (AAVSO) optical data were used for a time-series analysis of the long-term activity of Her X-1. The problem of measuring the long-term evolution of the X-ray intensity in the light curve which consists only of separated intense spikes was addressed. For this purpose, the fluence of each Main-On state was determined. The fluences vary generally (not only in the transitions into/from anomalous low states (ALSs)) by tens of percent on timescales of at least several epochs of the cycle length of the superorbital cyclemore » (but without any stable cycle) while irradiation of the donor producing the optical modulation remains considerably more stable. ALS1 and ALS2 are extensions of the tail in the statistical distribution of these fluences. In this interpretation, the variations of the fluences are caused by the changes of the structure of the inner disk region, which produces variable obscuration of the beams (emitting in the ASM band) at the neutron star. A small change of obscuration of these beams by the inner disk region suffices to change the fluences largely. However, the irradiation of the donor is changed significantly less because this inner disk region (which emits beyond the ASM band and acts as the occulting region of the beams) also irradiates the donor.« less

Spectral Variability of the UXOR Star RR Tau Over 2.5 Magnitudes in V

NASA Astrophysics Data System (ADS)

Rodgers, B.; Wooden, D. H.; Grinin, V. P.; Shakhovskoy, D.

2000-12-01

We present moderate resolution optical spectra of the highly variable Herbig Ae star RR Tau over 12 epochs spanning 2.5 magnitudes in V. The data cover most of the optical spectrum from the CaII K line in the blue to the CaII infrared triplet in the far red. Using contemporaneous photometric measurements from two sources, we have reliable estimates of the visual magnitude of the system at each spectral epoch. We find some spectral activity to be closely correlated with photometric variability, while other features are remarkably stable. Significant variability is common in the cores of Hα and Hβ , but is not well correlated with photometric variability. On the other hand, the wings (Δ v>400km/s) of the Balmer lines are quite stable, showing no change in spectral type when compared to Kurucz line profiles. This, along with the constant equivalent width seen in several weak metal lines, suggest that the physical conditions of the underlying continuum source are not changing significantly, despite a factor of ten change in brightness. In contrast, strong low-ionization permitted lines, such as FeII, CaII and NaI, are seen in deep absorption when the star is bright (V <= 12), but disappear during photometric minima to reveal weak emission lines. These absorption lines are not being filled in by the emission but rather are physically disappearing from the system. This could occur, for example, if an obscuring screen moved between the continuum source and the absorbing gas. The [OI]6300 line, a common wind diagnostic, is seen in emission at all epochs, with flux which is roughly constant except increasing slightly when the system is faint. We discuss these data in the context of different scenarios for the photometric variability and find them to be more consistent with the obscuration hypothesis, than changing accretion luminosity. This work is part of the dissertation research of B. Rodgers, which has been funded in large part by a NASA Graduate Student Research Program (GSRP) grant, for which D.H. Wooden is Rodgers' advisor. We gratefully acknowledge the use of the database of the Amateur Astronomers Variable Star Organization (AAVSO).

Variations in the Orbital Light Curve of the Magnetic Cataclysmic Variable Star QQ Vulpecula (Abstract)

NASA Astrophysics Data System (ADS)

Rose, S. C.

2017-06-01

(Abstract only) Magnetic cataclysmic variable stars have brightness variations that repeat with each revolution of the two stars about the center of mass of the system. However, in the case of QQ Vulpecula, this brightness variation pattern changes in the long term. This study makes use of two decades worth of data from the Roboscope Telescope as well as data from the American Association of Variable Star Observers (AAVSO) database to examine the long-term evolution of QQ Vul's phase curves. Nightly observations using the Maria Mitchell Association Vestal and Loines Observatory supplemented this analysis by clarifying short-term brightness variation. The long-term data was divided into four commonly observed behavioral types ranging from a double peaked curve of 15.5 magnitude to a 15.0 magnitude curve that had a primary minimum and a slow, linear rise in brightness in place of the secondary minimum. The nightly data kept within the confines of these categories, though the secondary minimum in the nightly data never vanished. No periodicity was found in the long-term variations. The model often invoked to explain the double peaked curve consists of single pole accretion in which a partial self-eclipse causes the secondary minimum and cyclotron beaming causes the primary minimum. However, the long-term variation may indicate a changing accretion rate, which may manifest itself in changes to the shape, size, or location of the accretion spot on the white dwarf such that it lessens or removes the secondary minimum. This project was supported by the NSF REU grant AST-1358980, the Massachusetts Space Grant, and the Nantucket Maria Mitchell Association.

Long-term Accretion Variations of the Magnetic Cataclysmic Variable Star QQ Vulpecula

NASA Astrophysics Data System (ADS)

Cooper Rose, Sanaea; Kafka, Stella; Jorgenson, Regina; Carr, Derrick; Childs, Francesca; Christenson, Holly; Karim, Md. Tanveer; Konchady, Tarini; Walker, Gary E.; Honeycutt, R. K.

2017-01-01

Magnetic cataclysmic variable stars have brightness variations that repeat with each revolution of the two stars about the center of mass of the system. However, in the case of QQ Vulpecula (QQ Vul), this brightness variation pattern changes in the long term. This study makes use of two decades worth of data from the Roboscope Telescope as well as data from the American Association of Variable Star Observers (AAVSO) database to examine the long-term evolution of QQ Vul’s phase curves. Nightly observations using the Maria Mitchell Association's Vestal and Loines Observatories supplemented this analysis by clarifying short-term brightness variation. The long-term data was divided into four commonly observed behavioral types ranging from a double peaked curve of ~15.5 magnitude to a ~15.0 magnitude curve that had a primary minimum and a slow, linear rise in brightness in place of the secondary minimum. The nightly data kept within the confines of these categories, though the secondary minimum in the nightly data never vanished. No periodicity was found in the long-term variations. The model often invoked to explain the double peaked curve consists of single pole accretion in which a partial self-eclipse causes the secondary minimum and cyclotron beaming causes the primary minimum. However, the long-term variation may indicate a changing accretion rate, which may manifest itself in changes to the shape, size, or location of the accretion spot on the white dwarf such that it lessens or removes the secondary minimum. This project was supported by the NSF REU grant AST-1358980, the Massachusetts Space Grant, and the Nantucket Maria Mitchell Association.

New O-C Observations for 150 Algols: Insight to the Origins of Period Shifts

NASA Astrophysics Data System (ADS)

Hoffman, D. I.; Harrison, T. E.; McNamara, B. J.; Vestrand, W. T.

2005-12-01

Many eclipsing binaries of type Algol, RS CVn, and W UMa have observed orbital period shifts. Of these, many show both increasing and decreasing period shifts. Two leading explanations for these shifts are third body effects and magnetic activity changing the oblateness of the secondary, though neither one can explain all of the observed period oscillations. The first-generation Robotic Optical Transient Search Experiment (ROTSE-I) based in Los Alamos, NM, was primarily designed to look for the optical counterparts to gamma-ray bursts as well as searching for other optical transients not detected in gamma-rays. The telescope, consisting of four 200mm camera lenses, can image the entire northern sky twice in a night, which is a very useful tool in monitoring relatively bright eclipsing binaries for period shifts. The public data release from ROTSE-I, the Northern Sky Variability Survey (NSVS), spans one year of data stating in April, 1999. O-C data for 150 eclipsing binaries are presented using the NSVS data. We revisit work by Borkovits and Hegedüs on some third body candidates in several eclipsing binary systems using recent AAVSO and NSVS data. Some unusual light curves of eclipsing binaries produced from NSVS data is presented and discussed.

Modeling SOFIA/FORCAST spectra of the classical nova V5568 Sgr with 3D pyCloudy

NASA Astrophysics Data System (ADS)

Calvén, Emilia; Helton, L. Andrew; Sankrit, Ravi

2017-06-01

We present our first results modelling Nova V5668 Sgr using the pseudo-3D photoionization code pyCloudy (Morisset 2013). V5668 Sgr is a classical nova of the FeII class (Williams et al. 2015; Seach 2015) showing signs of a bipolar flow (Banerjee et al. 2015). We construct a grid of models, which use hour-glass morphologies and a range of C, N, O and Ne abundances, to fit a suite of spectroscopic data in the near and mid-IR obtained between 82 to 556 days after outburst. The spectra were obtained using the FORCAST mid-IR instrument onboard the NASA Stratospheric Observatory for Infrared Astronomy (SOFIA) and the 1.2m near-IR telescope of the Mount Abu Infrared Observatory. Additional photometric data from FORCAST, The STONY BROOK/SMARTS Atlas of (mostly) Southern Novae (Walter et al., 2012) and the American Association of Variable Star Observers (AAVSO) were used to supplement the spectral data to obtain the SED of the nova at different times during its evolution. The work presented here is the initial step towards developing a large database of 1D and 3D models that may be used to derive the elemental abundances and dust properties of classical novae.

Why are the Daily Sunspot Observations Interesting? One Observer's Perspective (Abstract)

NASA Astrophysics Data System (ADS)

Dempsey, F.

2016-06-01

(Abstract only) Daily sunspot counts made for the AAVSO Solar Section may cause the observer to feel in touch with the daily (and longer-term) changes on the sun's surface, and this connection may be more interesting when the solar observer remains aware of the larger solar and geomagnetic environment. The daily sunspot observations may become more interesting when correlated with transient events including solar flares, filaments, coronal holes, and coronal mass ejections that can be followed in near-real time multi-wavelength X-ray and UV solar images as well as particle flux and magnetic field measurements.

The Enigma of the Open Cluster M29(NGC 6913) Solved

DTIC Science & Technology

2014-10-13

Survey ( 2MASS ) system (Skrutskie et al. 2006) and the ratios of color excesses EV−m/EB−V , where m are the near-infrared magnitudes J, H, and K. In...andEV−K/EB−V with the J, H, and K magnitudes from 2MASS . For this aim, we used a list of B and A stars identified in the central 15′ × 15′ area. Their...V and B − V data were taken from Massey et al. (1995) and the AAVSO APASS survey, DR7,7 and the near-infrared magnitudes from 2MASS . The ratios of

Planetary Transits of the Trans-Atlantic Exoplanet Survey Candidate TrES-1b

NASA Astrophysics Data System (ADS)

Price, A.; Bissinger, R.; Laughlin, G. P.; Gary, B. L.; Vanmunster, T.; Henden, A. A.; Starkey, D. R.; Kaiser, D. H.; Holtzman, J. A.; Marschall, L. A.; Michalik, T.; Wellington, T.; Paakkonen, P.

2005-08-01

The AAVSO compiled 10,560 CCD observations of the suspected exoplanet transit object TrES-1b covering seven complete transit windows, three windows of partial coverage, and coverage of baseline non-transit periods. Visual inspection of the light curves reveals the presence of slight humps at the egress points of some transits. A boot strap Monte Carlo simulation was applied to the data to confirm that the humps exist to a statistically significant degree. However, it does not rule out systemic effects which will be tested with campaigns in the 2005 observing season.

The Crucial Role of Amateur-Professional Networks in the Golden Age of Large Surveys (Abstract)

NASA Astrophysics Data System (ADS)

Rodriguez, J. E.

2017-06-01

(Abstract only) With ongoing projects such as HATNet, SuperWASP, KELT, MEarth, and the CoRoT and Kepler/K2 mission, we are in a golden era of large photometric surveys. In addition, LSST and TESS will be coming online in the next three to five years. The combination of all these projects will increased the number of photometrically monitored stars by orders of magnitude. It is expected that these surveys will enhance our knowledge of circumstellar architecture and the early stages of stellar and planetary formation, while providing a better understanding of exoplanet demographics. However, the success of these surveys will be dependent on simultaneous and continued follow up by large networks. With federal scientific funding reduced over the past few years, the availability of astronomical observations has been directly affected. Fortunately, ground based amateur-professional networks like the AAVSO and the KELT Follow-up Network (KELT-FUN) are already providing access to an international, independent resource for professional grade astronomical observations. These networks have both multi-band photometric and spectroscopic capabilities. I provide an overview of the ongoing and future surveys, highlight past and current contributions by amateur-professional networks to scientific discovery, and discuss the role of these networks in upcoming projects.

The Stars Belong to Everyone: Astronomer and Science Writer Dr. Helen Sawyer Hogg (1905-1993)

NASA Astrophysics Data System (ADS)

Cahill, Maria J.

2011-05-01

University of Toronto astronomer and science writer Helen Sawyer Hogg (President of the AAVSO 1939-41) served her field through research, teaching, and administrative leadership. Additionally, she reached out to students and the public through her Toronto Star newspaper column entitled "With the Stars" for thirty years; she wrote The Stars Belong to Everyone, a book that speaks to a lay audience; she hosted a successful television series entitled Ideas; and she delivered numerous speeches at scientific conferences, professional women's associations, school programs, libraries, and other venues. This paper will illumine her life and the personal and professional forces that influenced her work.

Adventures in transformations: TG, TA, oh my! (Poster abstract)

NASA Astrophysics Data System (ADS)

Ciocca, M.

2015-12-01

(Abstract only) AAVSO made available, through the great volunteer work of Gordon Myers and George Silvis, two very useful tools, Transform Generator and Transform Applier (TG and TA) for transforming instrumental magnitudes to the standard system. I will juxtapose the steps necessary to obtain transformation parameters "the old fashion way" and how can the same result be achieved with these two tools. I will present transformation parameters for the Eastern Kentucky University (EKU) telescope and obtained with the standard field M67. These parameters were applied to photometric results for AE Uma, a short-period, high-amplitude delta Scuti star (Period ~ 0.086 d).

Fermi-LAT Gamma-ray Observations of Nova Lupus 2016 (ASASSN-16kt)

NASA Astrophysics Data System (ADS)

Cheung, C. C.; Jean, P.; Shore, S. N.; Fermi Large Area Telescope Collaboration

2016-10-01

The Fermi Gamma-ray Space Telescope performed a ~6-day Target of Opportunity (ToO) observation of Nova Lupus 2016 (ATel #9538, #9539, CBET #4322) that commenced on September 28. Considering earlier all-sky survey Large Area Telescope (LAT) observations as well, preliminary analysis indicates gamma-ray emission at ~2 sigma was detected around 1 to 2 days after the optical peak on September 25th (pre-validated AAVSO visual lightcurve; ATel #9550, CBET #4322) when the optical spectra show opaque ejecta, similar to previous gamma-ray detected novae (Fermi-LAT collaboration, 2014 Science 345, 554; Cheung et al. 2016 ApJ 826, 142).

Near-infrared Observations of SiO Maser-emitting Asymptotic Giant Branch (AGB) Stars

NASA Astrophysics Data System (ADS)

Chibueze, James O.; Miyahara, Takeshi; Omodaka, Toshihiro; Ohta, Takashi; Fujii, Takahiro; Tanaka, Masuo; Motohara, Kentaro; Makoto, Miyoshi

2016-02-01

Near-infrared (NIR) monitoring observations of asymptotic giant branch stars exciting bright SiO masers have been made with the 1 m telescope of Kagoshima University. In order to investigate the properties of these stars and their envelopes, we combined our NIR photometric data with mid- and far-infrared flux data obtained by the IRAS satellite, SiO maser flux data provided by the Nobeyama Radio Observatory, visual magnitude data provided by the AAVSO, and the reported data on the expansion velocities of the circumstellar envelopes. The absolute magnitudes at the K-band and the distances are estimated using the period-luminosity relation of Mira variables determined by Feast et al. Then, mass-loss rates and isotropic luminosities of an SiO maser are estimated. The mass-loss rates range from approximately 10-8 {M}⊙ \\{{yr}}-1 to over 10-5 {M}⊙ {{yr}}-1. We found that the NIR pulsation amplitudes are correlated with the pulsation periods and the observed wavelengths. We also found correlations of the isotropic luminosities of SiO masers with the mass-loss rates and absolute magnitudes at the K-band. These results will help us to understand the pumping mechanism of SiO masers. We measured, for the first time, the periods and/or NIR magnitudes of TX Cam, BW Cam, IRAS 06297+4045, IRAS 18387-0423, and RT Cep.

Astronomy Education in Greece

NASA Astrophysics Data System (ADS)

Metaxa, M.

Basic education is fundamental to higher education and scientific and technological literacy. We can confront the widespread adult ignorance and apathy about science and technology. Astronomy, an interdisciplinary science, enhances students' interest and overcomes educational problems. Three years ago, we developed astronomy education in these ways: 1. Summer School for School Students. (50 students from Athens came to the first Summer School in Astrophysics at the National Observatory, September 2-5, 1996, for lectures by professional astronomers and to be familiarized with observatory instruments. 2. Introducing Students to Research. (This teaches students more about science so they are more confident about it. Our students have won top prizes in European research contests for their studies of objects on Schmidt plates and computations on PCs.) 3. Hands-on Activities. (Very important because they bring students close to their natural environment. Activities are: variable-star observations (AAVSO), Eratosthenes project, solar-eclipse, sunspot and comet studies. 4. Contact with Professional Astronomers and Institutes. (These help students reach their social environment and motivate them as "science carriers". We try to make contacts at astronomical events, and through visits to appropriate institutions.) 5. Internet Programs. (Students learn about and familiarize themselves with their technological environment.) 6. Laboratory exercises. (Students should do science, not just learn about it We introduced the following lab. exercises: supernova remnants, galaxy classification, both from Schmidt plates, celestial sphere.

Aluminium oxide in the optical spectrum of VY Canis Majoris

NASA Astrophysics Data System (ADS)

Kamiński, T.; Schmidt, M. R.; Menten, K. M.

2013-01-01

We report the first identification of the optical bands of the B 2Σ + -X 2Σ + system of AlO in the red supergiant VY CMa. In addition to TiO, VO, ScO, and YO, which were recognized in the optical spectrum of the star long time ago, AlO is another refractory molecule which displays strong emission bands in this peculiar star. Simulating the bands of AlO, we derive a rotational temperature of the circumstellar gas of Trot = 700 K. By resolving individual rotational components of the bands, we derive the kinematical characteristics of the gas, finding that the emission is centred at the stellar radial velocity and its intrinsic width is 13.5 km s-1 (full width at half maximum). It is the narrowest emission among all (thermal) features observed in VY CMa so far. The temperature and line widths suggest that the emission arises in gas located within ~20 stellar radii, where the outflow is still being accelerated. This result contradicts equilibrium-chemistry models which predict substantial AlO abundances only to within a few stellar radii. We argue that non-equilibrium models involving propagation of shocks are needed to explain the observations. This work makes use of data acquired within the ESO programmes 67.B-0504 and DDT 266.D-5655, and observations from the AAVSO International Database.

VizieR Online Data Catalog: Catalogue of variable stars in open clusters (Zejda+, 2012)

NASA Astrophysics Data System (ADS)

Zejda, M.; Paunzen, E.; Baumann, B.; Mikulasek, Z.; Liska, J.

2012-08-01

The catalogue of variable stars in open clusters were prepared by cross-matching of Variable Stars Index (http://www.aavso.org/vsx) version Apr 29, 2012 (available online, Cat. B/vsx) against the version 3.1. catalogue of open clusters DAML02 (Dias et al. 2002A&A...389..871D, Cat. B/ocl) available on the website http://www.astro.iag.usp.br/~wilton. The open clusters were divided into two categories according to their size, where the limiting diameter was 60 arcmin. The list of all suspected variables and variable stars located within the fields of open clusters up to two times of given cluster radius were generated (Table 1). 8938 and 9127 variable stars are given in 461 "smaller" and 74 "larger" clusters, respectively. All found variable stars were matched against the PPMXL catalog of positions and proper motions within the ICRS (Roeser et al., 2010AJ....139.2440R, Cat. I/317). Proper motion data were included in our catalogue. Unfortunately, a homogeneous data set of mean cluster proper motions has not been available until now. Therefore we used the following sources (sorted alphabetically) to compile a new catalogue: Baumgardt et al. (2000, Cat. J/A+AS/146/251): based on the Hipparcos catalogue Beshenov & Loktin (2004A&AT...23..103B): based on the Tycho-2 catalogue Dias et al. (2001, Cat. J/A+A/376/441, 2002A&A...389..871D, Cat. B/ocl): based on the Tycho-2 catalogue Dias et al. (2006, Cat. J/A+A/446/949): based on the UCAC2 catalog (Zacharias et al., 2004AJ....127.3043Z, Cat. I/289) Frinchaboy & Majewski (2008, Cat. J/AJ/136/118): based on the Tycho-2 catalogue Kharchenko et al. (2005, J/A+A/438/1163): based on the ASCC2.5 catalogue (Kharchenko, 2001KFNT...17..409K, Cat. I/280) Krone-Martins et al. (2010, Cat. J/A+A/516/A3): based on the Bordeaux PM2000 proper motion catalogue (Ducourant et al., 2006A&A...448.1235D, Cat. I/300) Robichon et al. (1999, Cat. J/A+A/345/471): based on the Hipparcos catalogue van Leeuwen (2009A&A...497..209V): based on the new Hipparcos catalogue. In total, a catalogue of proper motions for 879 open clusters (Table 2), from which 436 have more than one available measurement, was compiled. (3 data files).

High School Students Watching Stars Evolve

NASA Astrophysics Data System (ADS)

Percy, J. R.; MacNeil, D.; Meema-Coleman, L.; Morenz, K.

2012-06-01

(Abstract only) Some stars pulsate (vibrate). Their pulsation period depends primarily on their radius. The pulsation period changes if the radius changes, due to evolution, for instance. Even though the evolution is slow, the period change is measurable because it is cumulative. The observed time of maximum brightness (O) minus the calculated time (C), assuming that the period is constant, is plotted against time to produce an (O-C) diagram. If there is a uniform period change, this diagram will be a parabola, whose curvature - positive or negative - is proportional to the rate of period change. In this project, we study the period changes of RR Lyrae stars, old sun-like stars which are in the yellow giant phase, generating energy by thermonuclear fusion of helium into carbon. We chose 59 well-studied stars in the GEOS database, which consists of times of maximum measured by AAVSO and other observers. We included about a dozen RRc (first overtone pulsator) stars, since these have not been as well studied as the RRab (fundamental mode) stars because the maxima in their light curves are not as sharp. We will describe our results: about 2/3 of the stars showed parabolic (O-C) diagrams with period changes of up to 1.0 s/century, some with increasing periods and some with decreasing periods. The characteristic times for period changes (i.e. period divided by rate of change of period) were mostly 5-30 million years. These numbers are consistent with evolutionary models. Some stars showed too much scatter for analysis; we will discuss why. A few stars showed unusual (O-C) diagrams which cannot be explained simply by evolution. This project was carried out by coauthors MacNeil, Meema-Coleman, and Morenz, who were participants in the prestigious University of Toronto Mentorship Program, which enables outstanding senior high school students to participate in research at the university. We thank the AAVSO and other observers who made the measurements which were used in our project.

An 'Observational Large Ensemble' to compare observed and modeled temperature trend uncertainty due to internal variability.

NASA Astrophysics Data System (ADS)

Poppick, A. N.; McKinnon, K. A.; Dunn-Sigouin, E.; Deser, C.

2017-12-01

Initial condition climate model ensembles suggest that regional temperature trends can be highly variable on decadal timescales due to characteristics of internal climate variability. Accounting for trend uncertainty due to internal variability is therefore necessary to contextualize recent observed temperature changes. However, while the variability of trends in a climate model ensemble can be evaluated directly (as the spread across ensemble members), internal variability simulated by a climate model may be inconsistent with observations. Observation-based methods for assessing the role of internal variability on trend uncertainty are therefore required. Here, we use a statistical resampling approach to assess trend uncertainty due to internal variability in historical 50-year (1966-2015) winter near-surface air temperature trends over North America. We compare this estimate of trend uncertainty to simulated trend variability in the NCAR CESM1 Large Ensemble (LENS), finding that uncertainty in wintertime temperature trends over North America due to internal variability is largely overestimated by CESM1, on average by a factor of 32%. Our observation-based resampling approach is combined with the forced signal from LENS to produce an 'Observational Large Ensemble' (OLENS). The members of OLENS indicate a range of spatially coherent fields of temperature trends resulting from different sequences of internal variability consistent with observations. The smaller trend variability in OLENS suggests that uncertainty in the historical climate change signal in observations due to internal variability is less than suggested by LENS.

A Web-Remote/Robotic/Scheduled Astronomical Data Acquisition System

NASA Astrophysics Data System (ADS)

Denny, Robert

2011-03-01

Traditionally, remote/robotic observatory operating systems have been custom made for each observatory. While data reduction pipelines need to be tailored for each investigation, the data acquisition process (especially for stare-mode optical images) is often quite similar across investigations. Since 1999, DC-3 Dreams has focused on providing and supporting a remote/robotic observatory operating system which can be adapted to a wide variety of physical hardware and optics while achieving the highest practical observing efficiency and safe/secure web browser user controls. ACP Expert consists of three main subsystems: (1) a robotic list-driven data acquisition engine which controls all aspects of the observatory, (2) a constraint-driven dispatch scheduler with a long-term database of requests, and (3) a built-in "zero admin" web server and dynamic web pages which provide a remote capability for immediate execution and monitoring as well as entry and monitoring of dispatch-scheduled observing requests. No remote desktop login is necessary for observing, thus keeping the system safe and consistent. All routine operation is via the web browser. A wide variety of telescope mounts, CCD imagers, guiding sensors, filter selectors, focusers, instrument-package rotators, weather sensors, and dome control systems are supported via the ASCOM standardized device driver architecture. The system is most commonly employed on commercial 1-meter and smaller observatories used by universities and advanced amateurs for both science and art. One current project, the AAVSO Photometric All-Sky Survey (APASS), uses ACP Expert to acquire large volumes of data in dispatch-scheduled mode. In its first 18 months of operation (North then South), 40,307 sky images were acquired in 117 photometric nights, resulting in 12,107,135 stars detected two or more times. These stars had measures in 5 filters. The northern station covered 754 fields (6446 square degrees) at least twice, the southern station covered 951 fields (8500 square degrees) at least twice. The database of photometric calibrations is available from AAVSO. The paper will cover the ACP web interface, including the use of AJAX and JSON within a micro-content framework, as well as dispatch scheduler and acquisition engine operation.

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

NASA Astrophysics Data System (ADS)

Šimon, V.

2015-03-01

Context. GK Per is an intermediate polar that has been displaying dwarf nova outbursts since the middle of the twentieth century. Aims: I analyzed a series of such outbursts in the optical and X-ray bands. I pay attention to the relation of intensities of the optical and X-ray emissions, and its reproducibility in a series of these consecutive outbursts. Methods: This analysis uses the data from the BAT/Swift, ASM/RXTE, AAVSO, and AFOEV databases. It investigates the relation of the time evolution of the profiles of outbursts in the individual bands (hard X-ray, medium/hard X-ray, and optical). Results: This analysis shows that the X-ray intensity steeply rises only in the start of the optical outburst and steeply declines only when the optical outburst comes to its end. However, the 1.5-50 keV band intensity saturates and balances on a plateau during the outburst. (The longer the outburst, the longer its plateau.) The peak X-ray intensities of this series display a significantly narrower range than the optical ones (a factor of about two versus a factor of about eight). This implies a discrepancy between the mass flow through the disk and the production of the X-ray emission via bremsstrahlung at the polar caps of the white dwarf. This discrepancy is the largest in the time of the peak optical intensity when the whole disk (or at least its inner part) is in the hot state and the flow of matter through the disk is the greatest. This study shows that a series of outbursts constitutes more general properties of this discrepancy. I argue that the saturation of the X-ray luminosity in outburst cannot be caused by a dominant increase in X-ray absorption. In the interpretation, large structural changes of the accreting regions at the magnetic poles of the white dwarf occur during the outburst. A buried shock proposed by some authors for polars is also promising for explaining the X-ray light curves of outbursts of GK Per. This research made use of the BAT/Swift, ASM/RXTE, AAVSO, and AFOEV databases.

Dorrit Hoffleit: A Century of being a Woman in Astronomy

NASA Astrophysics Data System (ADS)

Hoffleit, Dorrit; Gay, P. L.

2006-12-01

From working as one of Harlan J. Smith's female calculators in 1928 to running Maria Mitchell Observatory in 1957 to being an emeritus research scientist at Yale University today, Dr. Dorrit Hoffleit has been a professional woman in astronomy for 78 years and an astronomy lover for a century. She has faced both accolades, starting with the Carolyn Wilby Prize in 1938 for her dissertation work, as well as discrimination, most notably being hired at the Aberdeen Proving Ground at a sub-professional rating during WWII. Through both good and bad, she kept her eye on the stars, and her focus on doing the best work she could. In this presentation, Dr. Hoffleit reflects on her experiences and her inspirations in an video-interview. Additionally, archival film provided by the AAVSO will be shown.

On the use of internal state variables in thermoviscoplastic constitutive equations

NASA Technical Reports Server (NTRS)

Allen, D. H.; Beek, J. M.

1985-01-01

The general theory of internal state variables are reviewed to apply it to inelastic metals in use in high temperature environments. In this process, certain constraints and clarifications will be made regarding internal state variables. It is shown that the Helmholtz free energy can be utilized to construct constitutive equations which are appropriate for metallic superalloys. Internal state variables are shown to represent locally averaged measures of dislocation arrangement, dislocation density, and intergranular fracture. The internal state variable model is demonstrated to be a suitable framework for comparison of several currently proposed models for metals and can therefore be used to exhibit history dependence, nonlinearity, and rate as well as temperature sensitivity.

The Effect of Stereoscopic ("3D") vs. 2D Presentation on Learning through Video and Film

NASA Astrophysics Data System (ADS)

Price, Aaron; Kasal, E.

2014-01-01

Two Eyes, 3D is a NSF-funded research project into the effects of stereoscopy on learning of highly spatial concepts. We report final results on one study of the project which tested the effect of stereoscopic presentation on learning outcomes of two short films about Type 1a supernovae and the morphology of the Milky Way. 986 adults watched either film, randomly distributed between stereoscopic and 2D presentation. They took a pre-test and post-test that included multiple choice and drawing tasks related to the spatial nature of the topics in the film. Orientation of the answering device was also tracked and a spatial cognition pre-test was given to control for prior spatial ability. Data collection took place at the Adler Planetarium's Space Visualization Lab and the project is run through the AAVSO.

Bounds on internal state variables in viscoplasticity

NASA Technical Reports Server (NTRS)

Freed, Alan D.

1993-01-01

A typical viscoplastic model will introduce up to three types of internal state variables in order to properly describe transient material behavior; they are as follows: the back stress, the yield stress, and the drag strength. Different models employ different combinations of these internal variables--their selection and description of evolution being largely dependent on application and material selection. Under steady-state conditions, the internal variables cease to evolve and therefore become related to the external variables (stress and temperature) through simple functional relationships. A physically motivated hypothesis is presented that links the kinetic equation of viscoplasticity with that of creep under steady-state conditions. From this hypothesis one determines how the internal variables relate to one another at steady state, but most importantly, one obtains bounds on the magnitudes of stress and back stress, and on the yield stress and drag strength.

Research Experiences for 14 Year Olds: preliminary report on the `Sky Explorer' pilot program at Springfield (MA) High School of Science and Technology

NASA Astrophysics Data System (ADS)

Tucker, G. E.

1997-05-01

This NSF supported program, emphasizing hands-on learning and observation with modern instruments, is described in its pilot phase, prior to being launched nationally. A group of 14 year old students are using a small (21 cm) computer controlled telescope and CCD camera to do: (1) a 'sky survey' of brighter celestial objects, finding, identifying, and learning about them, and accumulating a portfolio of images, (2) photometry of variable stars, reducing the data to get a light curve, and (3) learn modern computer-based communication/dissemination skills by posting images and data to a Web site they are designing (http://www.javanet.com/ sky) and contributing data to archives (e.g. AAVSO) via the Internet. To attract more interest to astronomy and science in general and have a wider impact on the school and surrounding community, peer teaching is used as a pedagogical technique and families are encouraged to participate. Students teach e.g. astronomy, software and computers, Internet, instrumentation, and observing to other students, parents and the community by means of daytime presentations of their results (images and data) and evening public viewing at the telescope, operating the equipment themselves. Students can contribute scientifically significant data and experience the `discovery' aspect of science through observing projects where a measurement is made. Their `informal education' activities also help improve the perception of science in general and astronomy in particular in society at large. This program could benefit from collaboration with astronomers wanting to organize geographically distributed observing campaigns coordinated over the Internet and willing to advise on promising observational programs for small telescopes in the context of current science.

APASS Landolt-Sloan BVgri Photometry of RAVE Stars. I. Data, Effective Temperatures, and Reddenings

NASA Astrophysics Data System (ADS)

Munari, U.; Henden, A.; Frigo, A.; Zwitter, T.; Bienaymé, O.; Bland-Hawthorn, J.; Boeche, C.; Freeman, K. C.; Gibson, B. K.; Gilmore, G.; Grebel, E. K.; Helmi, A.; Kordopatis, G.; Levine, S. E.; Navarro, J. F.; Parker, Q. A.; Reid, W.; Seabroke, G. M.; Siebert, A.; Siviero, A.; Smith, T. C.; Steinmetz, M.; Templeton, M.; Terrell, D.; Welch, D. L.; Williams, M.; Wyse, R. F. G.

2014-11-01

We provide AAVSO Photometric All-Sky Survey (APASS) photometry in the Landolt BV and Sloan g'r'i' bands for all 425,743 stars included in the fourth RAVE Data Release. The internal accuracy of the APASS photometry of RAVE stars, expressed as the error of the mean of data obtained and separately calibrated over a median of four distinct observing epochs and distributed between 2009 and 2013, is 0.013, 0.012, 0.012, 0.014, and 0.021 mag for the B, V, g', r', and i' bands, respectively. The equally high external accuracy of APASS photometry has been verified on secondary Landolt and Sloan photometric standard stars not involved in the APASS calibration process and on a large body of literature data on field and cluster stars, confirming the absence of offsets and trends. Compared with the Carlsberg Meridian Catalog (CMC-15), APASS astrometry of RAVE stars is accurate to a median value of 0.098 arcsec. Brightness distribution functions for the RAVE stars have been derived in all bands. APASS photometry of RAVE stars, augmented by 2MASS JHK infrared data, has been χ2 fitted to a densely populated synthetic photometric library designed to widely explore temperature, surface gravity, metallicity, and reddening. Resulting T eff and E B - V , computed over a range of options, are provided and discussed, and will be kept updated in response to future APASS and RAVE data releases. In the process, we find that the reddening caused by a homogeneous slab of dust, extending for 140 pc on either side of the Galactic plane and responsible for EpolesB-V = 0.036 ± 0.002 at the Galactic poles, is a suitable approximation of the actual reddening encountered at Galactic latitudes |b| >= 25°.

TIMSS 2011 User Guide for the International Database. Supplement 3: Variables Derived from the Student, Home, Teacher, and School Questionnaire Data

ERIC Educational Resources Information Center

Foy, Pierre, Ed.; Arora, Alka, Ed.; Stanco, Gabrielle M., Ed.

2013-01-01

This supplement contains documentation on all the derived variables contained in the TIMSS 2011 data files that are based on background questionnaire variables. These variables were used to report background data in the TIMSS 2011 International Results in Mathematics and TIMSS 2011 International Results in Science reports, and are made available…

Ground-based follow-up in relation to Kepler asteroseismic investigation

NASA Astrophysics Data System (ADS)

Uytterhoeven, K.; Briquet, M.; Bruntt, H.; De Cat, P.; Frandsen, S.; Gutiérrez-Soto, J.; Kiss, L.; Kurtz, D. W.; Marconi, M.; Molenda-Żakowicz, J.; Østensen, R.; Randall, S.; Southworth, J.; Szabó, R.

2010-12-01

The Kepler space mission, successfully launched in March 2009, is providing continuous and high-precision photometry of thousands of stars simultaneously. The uninterrupted time-series of stars of all known pulsation types are a precious source for asteroseismic studies. The Kepler data do not provide information on the physical parameters, such as T_eff, log g, metallicity, and v sin i, which are crucial for successful asteroseismic modelling. Additional ground-based time-series data are needed to characterize mode parameters in several types of pulsating stars. Therefore, ground-based multi-colour photometry and mid/high-resolution spectroscopy are needed to complement the space data. We present ground-based activities within KASC on selected asteroseismic Kepler targets of several pulsation types. Based on observations made with the Isaac Newton Telescope and William Herschel Telescope operated by the Isaac Newton Group, with the Nordic Optical Telescope, operated jointly by Denmark, Finland, Iceland, Norway, and Sweden, with the Italian Telescopio Nazionale Galileo (TNG) operated by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica), and with the Mercator telescope, operated by the Flemish Community, all on the island of La Palma at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias (IAC). Based on observations made with the IAC-80 operated on the island of Tenerife by the IAC at the Spanish Observatorio del Teide. Also based on observations taken at the observatories of Sierra Nevada, San Pedro Mártir, Vienna, Xinglong, Apache Point, Lulin, Tautenburg, McDonald, Skinakas, Pic du Midi, Mauna Kea, Steward Observatory, Mt. Wilson, Białków Observatory of the Wrocław University, Piszkésteto Mountain Station, and Observatoire de Haute Provence. Based on spectra taken at the Loiano (INAF - OA Bologna), Serra La Nave (INAF - OA Catania) and Asiago (INAF - OA Padova) observatories. Also based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck-Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC). We acknowledge with thanks the variable star observations from the AAVSO International Database contributed by observers worldwide and used in this research. Funding for the Kepler mission is provided by NASA's Science Mission Directorate. We thank the entire Kepler team for the development and operations of this outstanding mission.

Assessing the role of internal climate variability in Antarctica's contribution to future sea-level rise

NASA Astrophysics Data System (ADS)

Tsai, C. Y.; Forest, C. E.; Pollard, D.

2017-12-01

The Antarctic ice sheet (AIS) has the potential to be a major contributor to future sea-level rise (SLR). Current projections of SLR due to AIS mass loss remain highly uncertain. Better understanding of how ice sheets respond to future climate forcing and variability is essential for assessing the long-term risk of SLR. However, the predictability of future climate is limited by uncertainties from emission scenarios, model structural differences, and the internal variability that is inherently generated within the fully coupled climate system. Among those uncertainties, the impact of internal variability on the AIS changes has not been explicitly assessed. In this study, we quantify the effect of internal variability on the AIS evolutions by using climate fields from two large-ensemble experiments using the Community Earth System Model to force a three-dimensional ice sheet model. We find that internal variability of climate fields, particularly atmospheric fields, among ensemble members leads to significantly different AIS responses. Our results show that the internal variability can cause about 80 mm differences of AIS contribution to SLR by 2100 compared to the ensemble-mean contribution of 380-450 mm. Moreover, using ensemble-mean climate fields as the forcing in the ice sheet model does not produce realistic simulations of the ice loss. Instead, it significantly delays the onset of retreat of the West Antarctic Ice Sheet for up to 20 years and significantly underestimates the AIS contribution to SLR by 0.07-0.11 m in 2100 and up to 0.34 m in the 2250's. Therefore, because the uncertainty caused by internal variability is irreducible, we seek to highlight a critical need to assess the role of internal variability in projecting the AIS loss over the next few centuries. By quantifying the impact of internal variability on AIS contribution to SLR, policy makers can obtain more robust estimates of SLR and implement suitable adaptation strategies.

A Central Flash at an Occultation of a Bright Star by Pluto Soon Before New Horizons' Flyby

NASA Astrophysics Data System (ADS)

Pasachoff, Jay M.; Babcock, Bryce A.; Durst, Rebecca F.; Seeger, Christina H.; Levine, Stephen E.; Bosh, Amanda S.; Sickafoose, Amanda A.; Person, Michael J.; Abe, Fumio; Suzuki, Daisuke; Nagakane, Masayuki; Tristam, Paul J.

2015-11-01

From the Mt. John Observatory, New Zealand, we were so close to the center of the occultation path on 29 June 2015 UTC that we observed a modest central flash from the focusing of starlight from a 12th-magnitude star. The star was one of the brightest ever in our years of continual monitoring that started in 2002. At the time of Pluto's perihelion in 1989, it was feared from models that Pluto's atmosphere might collapse by now, a motivation for the timely launch of New Horizons; some models now allow Pluto to retain its atmosphere throughout its orbit.We used our frame-transfer CCD at 10 Hz with GPS timing on the 1-m McLellan telescope of Canterbury U. We also observed with a Lowell Obs. infrared camera on the "AAVSO" 0.6-m Optical Craftsman telescope; and obtained 3-color photometry at a slower cadence on a second 0.6-m telescope. We coordinated with the overflight of SOFIA and its 2.5-m telescope, which benefited from last-minute astrometry, and the Auckland Observatory's and other ground-based telescopes.Our light curves show a modest central flash; our tentative geometrical solution shows that we were only about 50 km from the occultation path's centerline. The flash is from rays lower than otherwise accessible in Pluto's atmosphere. Our light curves, at such high cadence that we see spikes caused by atmospheric effects that we had not seen so well since our 2002 Mauna Kea occultation observations, show that Pluto's atmosphere had not changed drastically since our previous year's observations. Our data provide a long-term context for New Horizon's highly-detailed observations of Pluto's atmosphere in addition to providing a chord for the geometrical solution that includes SOFIA's observations.Our observations were supported by NASA Planetary Astronomy grants NNX12AJ29G to Williams College, NNX15AJ82G to Lowell Observatory, and NNX10AB27G to MIT, and by the National Research Foundation of South Africa. We are grateful to Alan Gilmore, Pam Kilmartin, Robert Lucas, and Carolle Varughese for assistance at Mt. John. We thank the AAVSO for use of the AAVSOnet 0.6-m telescope and Arne Henden for assistance.

TEDS-M 2008 User Guide for the International Database. Supplement 3: Variables Derived from the Educator and Future Teacher Data

ERIC Educational Resources Information Center

Brese, Falk, Ed.

2012-01-01

This supplement contains documentation on all the derived variables contained in the TEDS-M educator and future teacher data files. These derived variables were used to report data in the TEDS-M international reports. The variables that constitute the scales and indices are made available as part of the TEDS-M International Database to be used in…

Role of Internal Variability in Surface Temperature and Precipitation Change Uncertainties over India.

NASA Astrophysics Data System (ADS)

Achutarao, K. M.; Singh, R.

2017-12-01

There are various sources of uncertainty in model projections of future climate change. These include differences in the formulation of climate models, internal variability, and differences in scenarios. Internal variability in a climate system represents the unforced change due to the chaotic nature of the climate system and is considered irreducible (Deser et al., 2012). Internal variability becomes important at regional scales where it can dominate forced changes. Therefore it needs to be carefully assessed in future projections. In this study we segregate the role of internal variability in the future temperature and precipitation projections over the Indian region. We make use of the Coupled Model Inter-comparison Project - phase 5 (CMIP5; Taylor et al., 2012) database containing climate model simulations carried out by various modeling centers around the world. While the CMIP5 experimental protocol recommended producing numerous ensemble members, only a handful of the modeling groups provided multiple realizations. Having a small number of realizations is a limitation in producing a quantification of internal variability. We therefore exploit the Community Earth System Model Large Ensemble (CESM-LE; Kay et al., 2014) dataset which contains a 40 member ensemble of a single model- CESM1 (CAM5) to explore the role of internal variability in Future Projections. Surface air temperature and precipitation change projections over regional and sub-regional scale are analyzed under the IPCC emission scenario (RCP8.5) for different seasons and homogeneous climatic zones over India. We analyze the spread in projections due to internal variability in the CESM-LE and CMIP5 datasets over these regions.

Does internal variability change in response to global warming? A large ensemble modelling study of tropical rainfall

NASA Astrophysics Data System (ADS)

Milinski, S.; Bader, J.; Jungclaus, J. H.; Marotzke, J.

2017-12-01

There is some consensus on mean state changes of rainfall under global warming; changes of the internal variability, on the other hand, are more difficult to analyse and have not been discussed as much despite their importance for understanding changes in extreme events, such as droughts or floodings. We analyse changes in the rainfall variability in the tropical Atlantic region. We use a 100-member ensemble of historical (1850-2005) model simulations with the Max Planck Institute for Meteorology Earth System Model (MPI-ESM1) to identify changes of internal rainfall variability. To investigate the effects of global warming on the internal variability, we employ an additional ensemble of model simulations with stronger external forcing (1% CO2-increase per year, same integration length as the historical simulations) with 68 ensemble members. The focus of our study is on the oceanic Atlantic ITCZ. We find that the internal variability of rainfall over the tropical Atlantic does change due to global warming and that these changes in variability are larger than changes in the mean state in some regions. From splitting the total variance into patterns of variability, we see that the variability on the southern flank of the ITCZ becomes more dominant, i.e. explaining a larger fraction of the total variance in a warmer climate. In agreement with previous studies, we find that changes in the mean state show an increase and narrowing of the ITCZ. The large ensembles allow us to do a statistically robust differentiation between the changes in variability that can be explained by internal variability and those that can be attributed to the external forcing. Furthermore, we argue that internal variability in a transient climate is only well defined in the ensemble domain and not in the temporal domain, which requires the use of a large ensemble.

Internal Variability-Generated Uncertainty in East Asian Climate Projections Estimated with 40 CCSM3 Ensembles.

PubMed

Yao, Shuai-Lei; Luo, Jing-Jia; Huang, Gang

2016-01-01

Regional climate projections are challenging because of large uncertainty particularly stemming from unpredictable, internal variability of the climate system. Here, we examine the internal variability-induced uncertainty in precipitation and surface air temperature (SAT) trends during 2005-2055 over East Asia based on 40 member ensemble projections of the Community Climate System Model Version 3 (CCSM3). The model ensembles are generated from a suite of different atmospheric initial conditions using the same SRES A1B greenhouse gas scenario. We find that projected precipitation trends are subject to considerably larger internal uncertainty and hence have lower confidence, compared to the projected SAT trends in both the boreal winter and summer. Projected SAT trends in winter have relatively higher uncertainty than those in summer. Besides, the lower-level atmospheric circulation has larger uncertainty than that in the mid-level. Based on k-means cluster analysis, we demonstrate that a substantial portion of internally-induced precipitation and SAT trends arises from internal large-scale atmospheric circulation variability. These results highlight the importance of internal climate variability in affecting regional climate projections on multi-decadal timescales.

Current and Future Decadal Trends in the Oceanic Carbon Uptake Are Dominated by Internal Variability

NASA Astrophysics Data System (ADS)

Li, Hongmei; Ilyina, Tatiana

2018-01-01

We investigate the internal decadal variability of the ocean carbon uptake using 100 ensemble simulations based on the Max Planck Institute Earth system model (MPI-ESM). We find that on decadal time scales, internal variability (ensemble spread) is as large as the forced temporal variability (ensemble mean), and the largest internal variability is found in major carbon sink regions, that is, the 50-65°S band of the Southern Ocean, the North Pacific, and the North Atlantic. The MPI-ESM ensemble produces both positive and negative 10 year trends in the ocean carbon uptake in agreement with observational estimates. Negative decadal trends are projected to occur in the future under RCP4.5 scenario. Due to the large internal variability, the Southern Ocean and the North Pacific require the most ensemble members (more than 53 and 46, respectively) to reproduce the forced decadal trends. This number increases up to 79 in future decades as CO2 emission trajectory changes.

On the Temporal Variability of Low-Mode Internal Tides in the Deep Ocean

NASA Technical Reports Server (NTRS)

Ray, Richard D.; Zaron, E. D.

2010-01-01

In situ measurements of internal tides are typically characterized by high temporal variability, with strong dependence on stratification, mesoscale eddies, and background currents commonly observed. Thus, it is surprising to find phase-locked internal tides detectable by satellite altimetry. An important question is how much tidal variability is missed by altimetry. We address this question in several ways. We subset the altimetry by season and find only very small changes -- an important exception being internal tides in the South China Sea where we observe strong seasonal dependence. A wavenumber-domain analysis confirms that throughout most of the global ocean there is little temporal variability in altimetric internal-tide signals, at least in the first baroclinic mode, which is the mode that dominates surface elevation. The analysis shows higher order modes to be significantly more variable. The results of this study have important practical implications for the anticipated SWOT wide-swath altimeter mission, for which removal of internal tide signals is critical for observing non-tidal submesoscale phenomena.

Correlates and consequences of internalized stigma for people living with mental illness: a systematic review and meta-analysis.

PubMed

Livingston, James D; Boyd, Jennifer E

2010-12-01

An expansive body of research has investigated the experiences and adverse consequences of internalized stigma for people with mental illness. This article provides a systematic review and meta-analysis of the extant research regarding the empirical relationship between internalized stigma and a range of sociodemographic, psychosocial, and psychiatric variables for people who live with mental illness. An exhaustive review of the research literature was performed on all articles published in English that assessed a statistical relationship between internalized stigma and at least one other variable for adults who live with mental illness. In total, 127 articles met the inclusion criteria for systematic review, of which, data from 45 articles were extracted for meta-analyses. None of the sociodemographic variables that were included in the study were consistently or strongly correlated with levels of internalized stigma. The review uncovered a striking and robust negative relationship between internalized stigma and a range of psychosocial variables (e.g., hope, self-esteem, and empowerment). Regarding psychiatric variables, internalized stigma was positively associated with psychiatric symptom severity and negatively associated with treatment adherence. The review draws attention to the lack of longitudinal research in this area of study which has inhibited the clinical relevance of findings related to internalized stigma. The study also highlights the need for greater attention on disentangling the true nature of the relationship between internalized stigma and other psychosocial variables. Copyright © 2010 Elsevier Ltd. All rights reserved.

International spinal cord injury endocrine and metabolic extended data set.

PubMed

Bauman, W A; Wecht, J M; Biering-Sørensen, F

2017-05-01

The objective of this study was to develop the International Spinal Cord Injury (SCI) Endocrine and Metabolic Extended Data Set (ISCIEMEDS) within the framework of the International SCI Data Sets that would facilitate consistent collection and reporting of endocrine and metabolic findings in the SCI population. This study was conducted in an international setting. The ISCIEMEDS was developed by a working group. The initial ISCIEMEDS was revised based on suggestions from members of the International SCI Data Sets Committee, the International Spinal Cord Society (ISCoS) Executive and Scientific Committees, American Spinal Injury Association (ASIA) Board, other interested organizations, societies and individual reviewers. The data set was posted for two months on ISCoS and ASIA websites for comments. Variable names were standardized, and a suggested database structure for the ISCIEMEDS was provided by the Common Data Elements (CDEs) project at the National Institute on Neurological Disorders and Stroke (NINDS) of the US National Institute of Health (NIH), and are available at https://commondataelements.ninds.nih.gov/SCI.aspx#tab=Data_Standards. The final ISCIEMEDS contains questions on the endocrine and metabolic conditions related to SCI. Because the information may be collected at any time, the date of data collection is important to determine the time after SCI. ISCIEMEDS includes information on carbohydrate metabolism (6 variables), calcium and bone metabolism (12 variables), thyroid function (9 variables), adrenal function (2 variables), gonadal function (7 variables), pituitary function (6 variables), sympathetic nervous system function (1 variable) and renin-aldosterone axis function (2 variables). The complete instructions for data collection and the data sheet itself are freely available on the website of ISCoS (http://www.iscos.org.uk/international-sci-data-sets).

Emotional variability in mother-adolescent conflict interactions and internalizing problems of mothers and adolescents: dyadic and individual processes.

PubMed

Van der Giessen, Daniëlle; Hollenstein, Tom; Hale, William W; Koot, Hans M; Meeus, Wim; Branje, Susan

2015-02-01

Emotional variability reflects the ability to flexibly switch among a broad range of positive and negative emotions from moment-to-moment during interactions. Emotional variability during mother-adolescent conflict interactions is considered to be important for healthy socio-emotional functioning of mothers and adolescents. The current observational study examined whether dyadic emotional variability, maternal emotional variability, and adolescent emotional variability during conflict interactions in early adolescence predicted mothers' and adolescents' internalizing problems five years later. We used data from 92 mother-adolescent dyads (Mage T1 = 13.05; 65.20 % boys) who were videotaped at T1 while discussing a conflict. Emotional variability was derived from these conflict interactions and it was observed for mother-adolescent dyads, mothers and adolescents separately. Mothers and adolescents also completed questionnaires in early adolescence (T1) and five years later in late adolescence (T6) on mothers' internalizing problems, and adolescents' anxiety and depressive symptoms. Hierarchical regression analyses showed that less dyadic emotional variability in early adolescence predicted relative increases in mothers' internalizing problems, adolescents' depressive symptoms, and adolescents' anxiety symptoms from early to late adolescence. Less maternal emotional variability only predicted relative increases in adolescents' anxiety symptoms over time. The emotional valence (e.g., types of emotions expressed) of conflict interactions did not moderate the results. Taken together, findings highlighted the importance of considering limited emotional variability during conflict interactions in the development, prevention, and treatment of internalizing problems of mothers and adolescents.

Analysis of model development strategies: predicting ventral hernia recurrence.

PubMed

Holihan, Julie L; Li, Linda T; Askenasy, Erik P; Greenberg, Jacob A; Keith, Jerrod N; Martindale, Robert G; Roth, J Scott; Liang, Mike K

2016-11-01

There have been many attempts to identify variables associated with ventral hernia recurrence; however, it is unclear which statistical modeling approach results in models with greatest internal and external validity. We aim to assess the predictive accuracy of models developed using five common variable selection strategies to determine variables associated with hernia recurrence. Two multicenter ventral hernia databases were used. Database 1 was randomly split into "development" and "internal validation" cohorts. Database 2 was designated "external validation". The dependent variable for model development was hernia recurrence. Five variable selection strategies were used: (1) "clinical"-variables considered clinically relevant, (2) "selective stepwise"-all variables with a P value <0.20 were assessed in a step-backward model, (3) "liberal stepwise"-all variables were included and step-backward regression was performed, (4) "restrictive internal resampling," and (5) "liberal internal resampling." Variables were included with P < 0.05 for the Restrictive model and P < 0.10 for the Liberal model. A time-to-event analysis using Cox regression was performed using these strategies. The predictive accuracy of the developed models was tested on the internal and external validation cohorts using Harrell's C-statistic where C > 0.70 was considered "reasonable". The recurrence rate was 32.9% (n = 173/526; median/range follow-up, 20/1-58 mo) for the development cohort, 36.0% (n = 95/264, median/range follow-up 20/1-61 mo) for the internal validation cohort, and 12.7% (n = 155/1224, median/range follow-up 9/1-50 mo) for the external validation cohort. Internal validation demonstrated reasonable predictive accuracy (C-statistics = 0.772, 0.760, 0.767, 0.757, 0.763), while on external validation, predictive accuracy dipped precipitously (C-statistic = 0.561, 0.557, 0.562, 0.553, 0.560). Predictive accuracy was equally adequate on internal validation among models; however, on external validation, all five models failed to demonstrate utility. Future studies should report multiple variable selection techniques and demonstrate predictive accuracy on external data sets for model validation. Copyright © 2016 Elsevier Inc. All rights reserved.

Relative controls of external and internal variability on time-variable transit time distributions, and the importance of StorAge Selection function approaches

NASA Astrophysics Data System (ADS)

Kim, M.; Pangle, L. A.; Cardoso, C.; Lora, M.; Meira, A.; Volkmann, T. H. M.; Wang, Y.; Harman, C. J.; Troch, P. A. A.

2015-12-01

Transit time distributions (TTDs) are an efficient way of characterizing complex transport dynamics of a hydrologic system. Time-invariant TTD has been studied extensively, but TTDs are time-varying under unsteady hydrologic systems due to both external variability (e.g., time-variability in fluxes), and internal variability (e.g., time-varying flow pathways). The use of "flow-weighted time" has been suggested to account for the effect of external variability on TTDs, but neglects the role of internal variability. Recently, to account both types of variability, StorAge Selection (SAS) function approaches were developed. One of these approaches enables the transport characteristics of a system - how the different aged water in the storage is sampled by the outflow - to be parameterized by time-variable probability distribution called the rank SAS (rSAS) function, and uses it directly to determine the time-variable TTDs resulting from a given timeseries of fluxes in and out of a system. Unlike TTDs, the form of the rSAS function varies only due to changes in flow pathways, but is not affected by the timing of fluxes alone. However, the relation between physical mechanisms and the time-varying rSAS functions are not well understood. In this study, relative effects of internal and external variability on the TTDs are examined using observations from a homogeneously packed 1 m3 sloping soil lysimeter. The observations suggest the importance of internal variability on TTDs, and reinforce the need to account for this variability using time-variable rSAS functions. Furthermore, the relative usefulness of two other formulations of SAS functions and the mortality rate (which plays a similar role to SAS functions in the McKendrick-von Foerster model of age-structured population dynamics) are also discussed. Finally, numerical modeling is used to explore the role of internal and external variability for hydrologic systems with diverse geomorphic and climate characteristics. This works will give an insight that which approach (or SAS function) is preferable under different conditions.

Observations of Local Positive Low Cloud Feedback Patterns and Their Role in Internal Variability and Climate Sensitivity

NASA Astrophysics Data System (ADS)

Yuan, Tianle; Oreopoulos, Lazaros; Platnick, Steven E.; Meyer, Kerry

2018-05-01

Modeling studies have shown that cloud feedbacks are sensitive to the spatial pattern of sea surface temperature (SST) anomalies, while cloud feedbacks themselves strongly influence the magnitude of SST anomalies. Observational counterparts to such patterned interactions are still needed. Here we show that distinct large-scale patterns of SST and low-cloud cover (LCC) emerge naturally from objective analyses of observations and demonstrate their close coupling in a positive local SST-LCC feedback loop that may be important for both internal variability and climate change. The two patterns that explain the maximum amount of covariance between SST and LCC correspond to the Interdecadal Pacific Oscillation and the Atlantic Multidecadal Oscillation, leading modes of multidecadal internal variability. Spatial patterns and time series of SST and LCC anomalies associated with both modes point to a strong positive local SST-LCC feedback. In many current climate models, our analyses suggest that SST-LCC feedback strength is too weak compared to observations. Modeled local SST-LCC feedback strength affects simulated internal variability so that stronger feedback produces more intense and more realistic patterns of internal variability. To the extent that the physics of the local positive SST-LCC feedback inferred from observed climate variability applies to future greenhouse warming, we anticipate significant amount of delayed warming because of SST-LCC feedback when anthropogenic SST warming eventually overwhelm the effects of internal variability that may mute anthropogenic warming over parts of the ocean. We postulate that many climate models may be underestimating both future warming and the magnitude of modeled internal variability because of their weak SST-LCC feedback.

Effects of Ensemble Configuration on Estimates of Regional Climate Uncertainties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Goldenson, N.; Mauger, G.; Leung, L. R.

Internal variability in the climate system can contribute substantial uncertainty in climate projections, particularly at regional scales. Internal variability can be quantified using large ensembles of simulations that are identical but for perturbed initial conditions. Here we compare methods for quantifying internal variability. Our study region spans the west coast of North America, which is strongly influenced by El Niño and other large-scale dynamics through their contribution to large-scale internal variability. Using a statistical framework to simultaneously account for multiple sources of uncertainty, we find that internal variability can be quantified consistently using a large ensemble or an ensemble ofmore » opportunity that includes small ensembles from multiple models and climate scenarios. The latter also produce estimates of uncertainty due to model differences. We conclude that projection uncertainties are best assessed using small single-model ensembles from as many model-scenario pairings as computationally feasible, which has implications for ensemble design in large modeling efforts.« less

The test of variables of attention (TOVA): Internal consistency (Q1 vs. Q2 and Q3 vs. Q4) in children with Attention Deficit/Hyperactivity Disorder (ADHD)

USDA-ARS?s Scientific Manuscript database

The internal consistency of the Test of Variables of Attention (TOVA) was examined in a cohort of 6- to 12-year-old children (N = 63) strictly diagnosed with ADHD. The internal consistency of errors of omission (OMM), errors of commission (COM), response time (RT), and response time variability (RTV...

Estimating the impact of internal climate variability on ice sheet model simulations

NASA Astrophysics Data System (ADS)

Tsai, C. Y.; Forest, C. E.; Pollard, D.

2016-12-01

Rising sea level threatens human societies and coastal habitats and melting ice sheets are a major contributor to sea level rise (SLR). Thus, understanding uncertainty of both forcing and variability within the climate system is essential for assessing long-term risk of SLR given their impact on ice sheet evolution. The predictability of polar climate is limited by uncertainties from the given forcing, the climate model response to this forcing, and the internal variability from feedbacks within the fully coupled climate system. Among those sources of uncertainty, the impact of internal climate variability on ice sheet changes has not yet been robustly assessed. Here we investigate how internal variability affects ice sheet projections using climate fields from two Community Earth System Model (CESM) large-ensemble (LE) experiments to force a three-dimensional ice sheet model. Each ensemble member in an LE experiment undergoes the same external forcings but with unique initial conditions. We find that for both LEs, 2m air temperature variability over Greenland ice sheet (GrIS) can lead to significantly different ice sheet responses. Our results show that the internal variability from two fully coupled CESM LEs can cause about 25 35 mm differences of GrIS's contribution to SLR in 2100 compared to present day (about 20% of the total change), and 100m differences of SLR in 2300. Moreover, only using ensemble-mean climate fields as the forcing in ice sheet model can significantly underestimate the melt of GrIS. As the Arctic region becomes warmer, the role of internal variability is critical given the complex nonlinear interactions between surface temperature and ice sheet. Our results demonstrate that internal variability from coupled atmosphere-ocean general circulation model can affect ice sheet simulations and the resulting sea-level projections. This study highlights an urgent need to reassess associated uncertainties of projecting ice sheet loss over the next few centuries to obtain robust estimates of the contribution of ice sheet melt to SLR.

The Theory of Thermodynamic Systems with Internal Variables of State: Necessary and Sufficient Conditions for Compliance with the Second Law of Thermodynamics

NASA Astrophysics Data System (ADS)

Shnip, A. I.

2018-01-01

Based on the entropy-free thermodynamic approach, a generalized theory of thermodynamic systems with internal variables of state is being developed. For the case of nonlinear thermodynamic systems with internal variables of state and linear relaxation, the necessary and sufficient conditions have been proved for fulfillment of the second law of thermodynamics in entropy-free formulation which, according to the basic theorem of the theory, are also necessary and sufficient for the existence of a thermodynamic potential. Moreover, relations of correspondence between thermodynamic systems with memory and systems with internal variables of state have been established, as well as some useful relations in the spaces of states of both types of systems.

Internal Validity: A Must in Research Designs

ERIC Educational Resources Information Center

Cahit, Kaya

2015-01-01

In experimental research, internal validity refers to what extent researchers can conclude that changes in dependent variable (i.e. outcome) are caused by manipulations in independent variable. The causal inference permits researchers to meaningfully interpret research results. This article discusses (a) internal validity threats in social and…

Uncertainties in Future Regional Sea Level Trends: How to Deal with the Internal Climate Variability?

NASA Astrophysics Data System (ADS)

Becker, M.; Karpytchev, M.; Hu, A.; Deser, C.; Lennartz-Sassinek, S.

2017-12-01

Today, the Climate models (CM) are the main tools for forecasting sea level rise (SLR) at global and regional scales. The CM forecasts are accompanied by inherent uncertainties. Understanding and reducing these uncertainties is becoming a matter of increasing urgency in order to provide robust estimates of SLR impact on coastal societies, which need sustainable choices of climate adaptation strategy. These CM uncertainties are linked to structural model formulation, initial conditions, emission scenario and internal variability. The internal variability is due to complex non-linear interactions within the Earth Climate System and can induce diverse quasi-periodic oscillatory modes and long-term persistences. To quantify the effects of internal variability, most studies used multi-model ensembles or sea level projections from a single model ran with perturbed initial conditions. However, large ensembles are not generally available, or too small, and computationally expensive. In this study, we use a power-law scaling of sea level fluctuations, as observed in many other geophysical signals and natural systems, which can be used to characterize the internal climate variability. From this specific statistical framework, we (1) use the pre-industrial control run of the National Center for Atmospheric Research Community Climate System Model (NCAR-CCSM) to test the robustness of the power-law scaling hypothesis; (2) employ the power-law statistics as a tool for assessing the spread of regional sea level projections due to the internal climate variability for the 21st century NCAR-CCSM; (3) compare the uncertainties in predicted sea level changes obtained from a NCAR-CCSM multi-member ensemble simulations with estimates derived for power-law processes, and (4) explore the sensitivity of spatial patterns of the internal variability and its effects on regional sea level projections.

Internalized stigma and its psychosocial correlates in Korean patients with serious mental illness.

PubMed

Kim, Woo Jung; Song, Youn Joo; Ryu, Hyun-Sook; Ryu, Vin; Kim, Jae Min; Ha, Ra Yeon; Lee, Su Jin; Namkoong, Kee; Ha, Kyooseob; Cho, Hyun-Sang

2015-02-28

We aimed to examine internalized stigma of patients with mental illness in Korea and identify the contributing factors to internalized stigma among socio-demographic, clinical, and psychosocial variables using a cross-sectional study design. A total of 160 patients were recruited from a university mental hospital. We collected socio-demographic data, clinical variables and administered self-report scales to measure internalized stigma and levels of self-esteem, hopelessness, social support, and social conflict. Internalized stigma was identified in 8.1% of patients in our sample. High internalized stigma was independently predicted by low self-esteem, high hopelessness, and high social conflict among the psychosocial variables. Our finding suggests that simple psychoeducation only for insight gaining cannot improve internalized stigma. To manage internalized stigma in mentally ill patients, it is needed to promote hope and self-esteem. We also suggest that a relevant psychosocial intervention, such as developing coping skills for social conflict with family, can help patients overcome their internalized stigma. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

A Thermodynamical Theory with Internal Variables Describing Thermal Effects in Viscous Fluids

NASA Astrophysics Data System (ADS)

Ciancio, Vincenzo; Palumbo, Annunziata

2018-04-01

In this paper the heat conduction in viscous fluids is described by using the theory of classical irreversible thermodynamics with internal variables. In this theory, the deviation from the local equilibrium is characterized by vectorial internal variables and a generalized entropy current density expressed in terms of so-called current multipliers. Cross effects between heat conduction and viscosity are also considered and some phenomenological generalizations of Fourier's and Newton's laws are obtained.

A viscoplastic model with application to LiF-22 percent CaF2 hypereutectic salt

NASA Technical Reports Server (NTRS)

Freed, A. D.; Walker, K. P.

1990-01-01

A viscoplastic model for class M (metal-like behavior) materials is presented. One novel feature is its use of internal variables to change the stress exponent of creep (where n is approximately = 5) to that of natural creep (where n = 3), in accordance with experimental observations. Another feature is the introduction of a coupling in the evolution equations of the kinematic and isotropic internal variables, making thermal recovery of the kinematic variable implicit. These features enable the viscoplastic model to reduce to that of steady-state creep in closed form. In addition, the hardening parameters associated with the two internal state variables (one scalar-valued, the other tensor-valued) are considered to be functions of state, instead of being taken as constant-valued. This feature enables each internal variable to represent a much wider spectrum of internal states for the material. The model is applied to a LiF-22 percent CaF2 hypereutectic salt, which is being considered as a thermal energy storage material for space-based solar dynamic power systems.

Impact of internal variability on projections of Sahel precipitation change

NASA Astrophysics Data System (ADS)

Monerie, Paul-Arthur; Sanchez-Gomez, Emilia; Pohl, Benjamin; Robson, Jon; Dong, Buwen

2017-11-01

The impact of the increase of greenhouse gases on Sahelian precipitation is very uncertain in both its spatial pattern and magnitude. In particular, the relative importance of internal variability versus external forcings depends on the time horizon considered in the climate projection. In this study we address the respective roles of the internal climate variability versus external forcings on Sahelian precipitation by using the data from the CESM Large Ensemble Project, which consists of a 40 member ensemble performed with the CESM1-CAM5 coupled model for the period 1920-2100. We show that CESM1-CAM5 is able to simulate the mean and interannual variability of Sahel precipitation, and is representative of a CMIP5 ensemble of simulations (i.e. it simulates the same pattern of precipitation change along with equivalent magnitude and seasonal cycle changes as the CMIP5 ensemble mean). However, CESM1-CAM5 underestimates the long-term decadal variability in Sahel precipitation. For short-term (2010-2049) and mid-term (2030-2069) projections the simulated internal variability component is able to obscure the projected impact of the external forcing. For long-term (2060-2099) projections external forcing induced change becomes stronger than simulated internal variability. Precipitation changes are found to be more robust over the central Sahel than over the western Sahel, where climate change effects struggle to emerge. Ten (thirty) members are needed to separate the 10 year averaged forced response from climate internal variability response in the western Sahel for a long-term (short-term) horizon. Over the central Sahel two members (ten members) are needed for a long-term (short-term) horizon.

Response of ENSO amplitude to global warming in CESM large ensemble: uncertainty due to internal variability

NASA Astrophysics Data System (ADS)

Zheng, Xiao-Tong; Hui, Chang; Yeh, Sang-Wook

2018-06-01

El Niño-Southern Oscillation (ENSO) is the dominant mode of variability in the coupled ocean-atmospheric system. Future projections of ENSO change under global warming are highly uncertain among models. In this study, the effect of internal variability on ENSO amplitude change in future climate projections is investigated based on a 40-member ensemble from the Community Earth System Model Large Ensemble (CESM-LE) project. A large uncertainty is identified among ensemble members due to internal variability. The inter-member diversity is associated with a zonal dipole pattern of sea surface temperature (SST) change in the mean along the equator, which is similar to the second empirical orthogonal function (EOF) mode of tropical Pacific decadal variability (TPDV) in the unforced control simulation. The uncertainty in CESM-LE is comparable in magnitude to that among models of the Coupled Model Intercomparison Project phase 5 (CMIP5), suggesting the contribution of internal variability to the intermodel uncertainty in ENSO amplitude change. However, the causations between changes in ENSO amplitude and the mean state are distinct between CESM-LE and CMIP5 ensemble. The CESM-LE results indicate that a large ensemble of 15 members is needed to separate the relative contributions to ENSO amplitude change over the twenty-first century between forced response and internal variability.

Spectroscopic and photometric oscillatory envelope variability during the S Doradus outburst of the luminous blue variable R71

NASA Astrophysics Data System (ADS)

Mehner, A.; Baade, D.; Groh, J. H.; Rivinius, T.; Hambsch, F.-J.; Bartlett, E. S.; Asmus, D.; Agliozzo, C.; Szeifert, T.; Stahl, O.

2017-12-01

Context. Luminous blue variables (LBVs) are evolved massive stars that exhibit instabilities that are not yet understood. Stars can lose several solar masses during this evolutionary phase. The LBV phenomenon is thus critical to our understanding of the evolution of the most massive stars. Aims: The LBV R71 in the Large Magellanic Cloud is presently undergoing an S Doradus outburst, which started in 2005. To better understand the LBV phenomenon, we determine the fundamental stellar parameters of R71 during its quiescence phase. In addition, we analyze multiwavelength spectra and photometry obtained during the current outburst. Methods: We analyzed pre-outburst CASPEC spectra from 1984-1997, EMMI spectra in 2000, UVES spectra in 2002, and FEROS spectra from 2005 with the radiative transfer code CMFGEN to determine the fundamental stellar parameters of the star. A spectroscopic monitoring program with VLT X-shooter since 2012 secured visual to near-infrared spectra throughout the current outburst, which is well-covered by ASAS and AAVSO photometry. Mid-infrared images and radio data were also obtained. Results: During quiescence, R71 has an effective temperature of Teff = 15 500 K and a luminosity of log(L∗/L⊙) = 5.78. We determine its mass-loss rate to 4.0 × 10-6M⊙ yr-1. We present the spectral energy distribution of R71 from the near-ultraviolet to the mid-infrared during its present outburst. Semi-regular oscillatory variability in the light curve of the star is observed during the current outburst. Absorption lines develop a second blue component on a timescale of twice that length. The variability may consist of one (quasi-)periodic component with P 425/850 d with additional variations superimposed. Conclusions: R71 is a classical LBV, but this star is at the lower luminosity end of this group. Mid-infrared observations suggest that we are witnessing dust formation and grain evolution. During its current S Doradus outburst, R71 occupies a region in the HR diagram at the high-luminosity extension of the Cepheid instability strip and exhibits similar irregular variations as RV Tau variables. LBVs do not pass the Cepheid instability strip because of core evolution, but they develop comparable cool, low-mass, extended atmospheres in which convective instabilities may occur. As in the case of RV Tau variables, the occurrence of double absorption lines with an apparent regular cycle may be due to shocks within the atmosphere and period doubling may explain the factor of two in the lengths of the photometric and spectroscopic cycles. Based on observations collected at ESO's Very Large Telescope under Prog-IDs: 69.D-0390(D), 289.D-5040(A), 290.D-5032(A), 091.D-0116(A, B), 092.D-0024(A), 094.D-0266(A, B, C), 096.D-0043(A, B, C), 097.D-0006(A, B), 598.D-0005(A, B) and at the MPG/ESO 2.2-m Telescope under Prog-IDs: 076.D-0609(A), 078.D-0790(B), 086.D-0997(A, B), 087.D-0946(A), 089.D-0975(A), 094.A-9029(D), 096.A-9039(A), 097.D-0612(A, B), 098.D-0071(A).

Progress in Quantitative Viral Load Testing: Variability and Impact of the WHO Quantitative International Standards

PubMed Central

Sun, Y.; Tang, L.; Procop, G. W.; Hillyard, D. R.; Young, S. A.; Caliendo, A. M.

2016-01-01

ABSTRACT It has been hoped that the recent availability of WHO quantitative standards would improve interlaboratory agreement for viral load testing; however, insufficient data are available to evaluate whether this has been the case. Results from 554 laboratories participating in proficiency testing surveys for quantitative PCR assays of cytomegalovirus (CMV), Epstein-Barr virus (EBV), BK virus (BKV), adenovirus (ADV), and human herpesvirus 6 (HHV6) were evaluated to determine overall result variability and then were stratified by assay manufacturer. The impact of calibration to international units/ml (CMV and EBV) on variability was also determined. Viral loads showed a high degree of interlaboratory variability for all tested viruses, with interquartile ranges as high as 1.46 log10 copies/ml and the overall range for a given sample up to 5.66 log10 copies/ml. Some improvement in result variability was seen when international units were adopted. This was particularly the case for EBV viral load results. Variability in viral load results remains a challenge across all viruses tested here; introduction of international quantitative standards may help reduce variability and does so more or less markedly for certain viruses. PMID:27852673

Testing Cataclysmic Variable Evolution Models with Light Curves of >10,000 Magnitudes Over >100 years and Fully-Corrected to Johnson B & V

NASA Astrophysics Data System (ADS)

Schaefer, Bradley E.

2014-06-01

A combination of magnitudes from the Harvard and Sonneberg plates stacks and the AAVSO data base can create very well-sampled light curves with >10,000 magnitudes and covering all of 1890-2014 for roughly a hundred cataclysmic variables (CVs; novae, novalikes, and dwarf novae). Care must be taken to get all these magnitudes into a modern magnitude system. For the archival plates, these are all close to the B magnitude system so that color terms are small, hence, with the use of modern B magnitudes for the comparison stars, these magnitudes can all be placed onto the Johnson B system. For the archival visual observations, the original comparison sequences can always be found, and the magnitudes for the CV and comparisons must be converted from visual to V, so that the reported magnitudes can be fully corrected to Johnson V. The uncertainties from the plates and the visual magnitudes can always be beaten down by daily or yearly averaging to typical real total error bars of ±0.03 mag, and these are always much smaller than the sampling error arising from flickering and greatly smaller than the range of variations. These very-well-sampled >100 year Johnson B & V light curves can be used to test long term evolution models for CVs. With colleagues, I have made light curves for old novae (GK Per from 1890-2014 with 47,000 mags, V603 Aql from 1898-2014 using 22,722 mags, Q Cyg from 1876-2014 with 6400 mags, T CrB from 1855-2014 using 104,000 mags), Z Cam stars (Z Cam from 1923-2014 with 90,000 mags), and dwarf novae (SS Cyg from 1896-2014 with 403,800 mags). The relative accretion rate is given by both the average flux and by the inverse of the average peak-to-peak time for the dwarf novae. By this means, I have measured the changes in the accretion rate for many CVs and how they change on a yearly basis for a century and longer. These observations are directly compared to various CV evolution models. A complex set of agreements and disagreements is found.

The CESM Large Ensemble Project: Inspiring New Ideas and Understanding

NASA Astrophysics Data System (ADS)

Kay, J. E.; Deser, C.

2016-12-01

While internal climate variability is known to affect climate projections, its influence is often underappreciated and confused with model error. Why? In general, modeling centers contribute a small number of realizations to international climate model assessments [e.g., phase 5 of the Coupled Model Intercomparison Project (CMIP5)]. As a result, model error and internal climate variability are difficult, and at times impossible, to disentangle. In response, the Community Earth System Model (CESM) community designed the CESM Large Ensemble (CESM-LE) with the explicit goal of enabling assessment of climate change in the presence of internal climate variability. All CESM-LE simulations use a single CMIP5 model (CESM with the Community Atmosphere Model, version 5). The core simulations replay the twenty to twenty-first century (1920-2100) 40+ times under historical and representative concentration pathway 8.5 external forcing with small initial condition differences. Two companion 2000+-yr-long preindustrial control simulations (fully coupled, prognostic atmosphere and land only) allow assessment of internal climate variability in the absence of climate change. Comprehensive outputs, including many daily fields, are available as single-variable time series on the Earth System Grid for anyone to use. Examples of scientists and stakeholders that are using the CESM-LE outputs to help interpret the observational record, to understand projection spread and to plan for a range of possible futures influenced by both internal climate variability and forced climate change will be highlighted the presentation.

Proposal of a socio-cognitive-behavioral structural equation model of internalized stigma in people with severe and persistent mental illness.

PubMed

Muñoz, Manuel; Sanz, María; Pérez-Santos, Eloísa; Quiroga, María de Los Ángeles

2011-04-30

The social stigma of mental illness has received much attention in recent years and its effects on diverse variables such as psychiatric symptoms, social functioning, self-esteem, self-efficacy, quality of life, and social integration are well established. However, internalized stigma in people with severe and persistent mental illness has not received the same attention. The aim of the present work was to study the relationships between the principal variables involved in the functioning of internalized stigma (sociodemographic and clinical variables, social stigma, psychosocial functioning, recovery expectations, empowerment, and discrimination experiences) in a sample of people with severe and persistent mental illness (N=108). The main characteristics of the sample and the differences between groups with high and low internalized stigma were analyzed, a correlation analysis of the variables was performed, and a structural equation model, integrating variables of social, cognitive, and behavioral content, was proposed and tested. The results indicate the relationships among social stigma, discrimination experiences, recovery expectation, and internalized stigma and their role in the psychosocial and behavioral outcomes in schizophrenia spectrum disorders. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Getting organized: A history of amateur astronomy in the United States

NASA Astrophysics Data System (ADS)

Williams, Thomas R.

2000-10-01

During the twentieth century, American amateur astronomers attempted to form national organizations with structures and intents similar to the British Astronomical Association (BAA), an amateur organization dedicated to the advancement of astronomy and widely admired by American amateurs and professionals alike. The Society for Practical Astronomy (1910), the American Amateur Astronomers Association (1935), and the National Astronomical Association (1945) were each intended to facilitate amateur scientific contributions in BAA-like topical sections, but each of these societies failed. Founded in 1911, the American Association of Variable Star Observers (AAVSO) and the American Meteor Society (AMS) provided an alternative for amateur astronomers who were interested in those specific topics. However, it was not until 1947, when the Association of Lunar and Planetary Observers (ALPO) formed, that another large segment of amateur astronomers found a home for their interests. A second mode of national organization succeeded at mid- century and grew to include most avocational astronomers. Founded in 1947, the Astronomical League consists of regional associations of local societies, and is oriented largely towards recreational astronomy. The League sponsors annual national and regional conventions, but contributes little to scientific programs. This study concludes that avocational astronomy cannot simply be compared with professional astronomy, and instead must be viewed on its own terms as a complex and variegated field. Although the failure of American amateurs to form a BAA-like organization was at first disappointing, the specialized associations of observers, together with a separate and larger organization devoted to recreational astronomy, have served the American astronomical community well. Professional support for both types of activity was facilitated in this mode of organization. The style in which professional support is rendered appears to be important, with strong volunteer member leadership more effective than a benevolent dictatorship by professionals. A journal in which amateur astronomers may publish observations, discuss techniques and share insights is critical for scientifically oriented associations, and provided a driving force for organizing and maintaining such associations.

26 CFR 1.467-5 - Section 467 rental agreements with variable interest.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 26 Internal Revenue 6 2010-04-01 2010-04-01 false Section 467 rental agreements with variable interest. 1.467-5 Section 1.467-5 Internal Revenue INTERNAL REVENUE SERVICE, DEPARTMENT OF THE TREASURY (CONTINUED) INCOME TAX (CONTINUED) INCOME TAXES Taxable Year for Which Deductions Taken § 1.467-5 Section 467...

New Perspectives on the Role of Internal Variability in Regional Climate Change and Climate Model Evaluation

NASA Astrophysics Data System (ADS)

Deser, C.

2017-12-01

Natural climate variability occurs over a wide range of time and space scales as a result of processes intrinsic to the atmosphere, the ocean, and their coupled interactions. Such internally generated climate fluctuations pose significant challenges for the identification of externally forced climate signals such as those driven by volcanic eruptions or anthropogenic increases in greenhouse gases. This challenge is exacerbated for regional climate responses evaluated from short (< 50 years) data records. The limited duration of the observations also places strong constraints on how well the spatial and temporal characteristics of natural climate variability are known, especially on multi-decadal time scales. The observational constraints, in turn, pose challenges for evaluation of climate models, including their representation of internal variability and assessing the accuracy of their responses to natural and anthropogenic radiative forcings. A promising new approach to climate model assessment is the advent of large (10-100 member) "initial-condition" ensembles of climate change simulations with individual models. Such ensembles allow for accurate determination, and straightforward separation, of externally forced climate signals and internal climate variability on regional scales. The range of climate trajectories in a given model ensemble results from the fact that each simulation represents a particular sequence of internal variability superimposed upon a common forced response. This makes clear that nature's single realization is only one of many that could have unfolded. This perspective leads to a rethinking of approaches to climate model evaluation that incorporate observational uncertainty due to limited sampling of internal variability. Illustrative examples across a range of well-known climate phenomena including ENSO, volcanic eruptions, and anthropogenic climate change will be discussed.

Internal Interdecadal Variability in CMIP5 Control Simulations

NASA Astrophysics Data System (ADS)

Cheung, A. H.; Mann, M. E.; Frankcombe, L. M.; England, M. H.; Steinman, B. A.; Miller, S. K.

2015-12-01

Here we make use of control simulations from the CMIP5 models to quantify the amplitude of the interdecadal internal variability component in Atlantic, Pacific, and Northern Hemisphere mean surface temperature. We compare against estimates derived from observations using a semi-empirical approach wherein the forced component as estimated using CMIP5 historical simulations is removed to yield an estimate of the residual, internal variability. While the observational estimates are largely consistent with those derived from the control simulations for both basins and the Northern Hemisphere, they lie in the upper range of the model distributions, suggesting the possibility of differences between the amplitudes of observed and modeled variability. We comment on some possible reasons for the disparity.

Evaluation of internal noise methods for Hotelling observers

NASA Astrophysics Data System (ADS)

Zhang, Yani; Pham, Binh T.; Eckstein, Miguel P.

2005-04-01

Including internal noise in computer model observers to degrade model observer performance to human levels is a common method to allow for quantitatively comparisons of human and model performance. In this paper, we studied two different types of methods for injecting internal noise to Hotelling model observers. The first method adds internal noise to the output of the individual channels: a) Independent non-uniform channel noise, b) Independent uniform channel noise. The second method adds internal noise to the decision variable arising from the combination of channel responses: a) internal noise standard deviation proportional to decision variable's standard deviation due to the external noise, b) internal noise standard deviation proportional to decision variable's variance caused by the external noise. We tested the square window Hotelling observer (HO), channelized Hotelling observer (CHO), and Laguerre-Gauss Hotelling observer (LGHO). The studied task was detection of a filling defect of varying size/shape in one of four simulated arterial segment locations with real x-ray angiography backgrounds. Results show that the internal noise method that leads to the best prediction of human performance differs across the studied models observers. The CHO model best predicts human observer performance with the channel internal noise. The HO and LGHO best predict human observer performance with the decision variable internal noise. These results might help explain why previous studies have found different results on the ability of each Hotelling model to predict human performance. Finally, the present results might guide researchers with the choice of method to include internal noise into their Hotelling models.

Editorial: Papers from the 7th International Conference on Dendrochronology - Cultural Diversity, Environmental Variability

Treesearch

Margaret S. Devall; Elaine K. Sutherland

2008-01-01

The 7th International Conference on Dendrochronology - Cultural Diversity, Environmental Variability was held in Beijing, China from 11 to 17 June 2006. The conference was organized and hosted by the Institute of Botany, Chinese Academy of Sciences (IB_CAS) in conjunction with the International Union of Forest Research Organizations (IUFRO) Working Group 5.01.07 (Tree-...

Uncovering the Anthropogenic Sea Level Change using an Improved Sea Level Reconstruction for the Indian Ocean

NASA Astrophysics Data System (ADS)

Kumar, P.; Hamlington, B.; Thompson, P. R.; Han, W.

2016-12-01

Despite having some of the world's most densely populated and vulnerable coastal regions, sea level (SL) variability in the Indian Ocean (IO) has received considerably less attention than the Pacific Ocean. Differentiating the internal variability from the long-term trend in global mean sea level (GMSL) at decadal time-scales is vital for planning and mitigation efforts in the IO region. Understanding the dynamics of internal and anthropogenic SL change is essential for understanding the dynamic pathways that link the IO basin to terrestrial climates world-wide. With a sparse pre-satellite observational record of the IO, the Indo-Pacific internal climate variability is difficult to represent accurately. However, an improved representation of pre-satellite SL variability can be achieved by using a multivariate reconstruction technique. By using cyclostationary empirical orthogonal functions (CSEOFs) that can capture time-varying spatial patterns, gaps in the historical record when observations are sparse are filled using spatial relationships from time periods when the observational network is dense. This reconstruction method combines SL data and sea surface temperature (SST) to create a SL reconstruction that spans a period from 1900 to present, long enough to study climate signals over interannual to decadal time scales. This study aims at estimating the component of SL rise that relates to anthropogenic forcing by identifying and removing the fraction related to internal variability. An improved understanding of how the internal climate variability can affect the IO SL trend and variability, will provide an insight into the future SL changes. It is also important to study links between SL and climate variability in the past to understand how SL will respond to similar climatic events in the future and if this response will be influenced by the changing climate.

Internal versus external controls on age variability: Definitions, origins and implications in a changing climate

NASA Astrophysics Data System (ADS)

Helton, A. M.; Poole, G. C.; Payn, R. A.; Izurieta, C.; Wright, M.; Bernhardt, E. S.; Stanford, J. A.

2014-12-01

The unsteadiness of stream water age is now well established, but the controls on the age dynamics, and the adequate representation and prediction of those dynamics, are not. A basic distinction can be made between internal variability that arises from changes in the proportions of flow moving through the diverse flow pathways of a hydrologic system, and external variability that arises from the stochasticity of inputs and outputs (such as precipitation and streamflow). In this talk I will show how these two types of age variability can be formally defined and distinguished within the framework of rank StorAge Selection (rSAS) functions. Internal variability implies variations in time in the rSAS function, while external variability does not. This leads naturally to the definition of several modes of internal variability, reflecting generic ways that system flowpaths may be rearranged. This rearrangement may be induced by fluctuations in the system state (such as catchment wetness), or by longer-term changes in catchment structure (such as land use change). One type of change, the 'inverse storage effect' is characterized by an increase in the release of young water from the system in response to an increase in overall system storage. This effect can be seen in many hydrologic settings, and has important implications for the effect of altered hydroclimatic conditions on solute transport through a landscape. External variability, such as increased precipitation, can induce a decrease in mean transit time (and vice versa), but this effect is greatly enhanced if accompanied by an internal shift in flow pathways that increases the relative importance of younger water. These effects will be illustrated using data from field and experimental studies.

Internal versus external controls on age variability: Definitions, origins and implications in a changing climate

NASA Astrophysics Data System (ADS)

Harman, C. J.

2015-12-01

The unsteadiness of stream water age is now well established, but the controls on the age dynamics, and the adequate representation and prediction of those dynamics, are not. A basic distinction can be made between internal variability that arises from changes in the proportions of flow moving through the diverse flow pathways of a hydrologic system, and external variability that arises from the stochasticity of inputs and outputs (such as precipitation and streamflow). In this talk I will show how these two types of age variability can be formally defined and distinguished within the framework of rank StorAge Selection (rSAS) functions. Internal variability implies variations in time in the rSAS function, while external variability does not. This leads naturally to the definition of several modes of internal variability, reflecting generic ways that system flowpaths may be rearranged. This rearrangement may be induced by fluctuations in the system state (such as catchment wetness), or by longer-term changes in catchment structure (such as land use change). One type of change, the 'inverse storage effect' is characterized by an increase in the release of young water from the system in response to an increase in overall system storage. This effect can be seen in many hydrologic settings, and has important implications for the effect of altered hydroclimatic conditions on solute transport through a landscape. External variability, such as increased precipitation, can induce a decrease in mean transit time (and vice versa), but this effect is greatly enhanced if accompanied by an internal shift in flow pathways that increases the relative importance of younger water. These effects will be illustrated using data from field and experimental studies.

Hydration level is an internal variable for computing motivation to obtain water rewards in monkeys.

PubMed

Minamimoto, Takafumi; Yamada, Hiroshi; Hori, Yukiko; Suhara, Tetsuya

2012-05-01

In the process of motivation to engage in a behavior, valuation of the expected outcome is comprised of not only external variables (i.e., incentives) but also internal variables (i.e., drive). However, the exact neural mechanism that integrates these variables for the computation of motivational value remains unclear. Besides, the signal of physiological needs, which serves as the primary internal variable for this computation, remains to be identified. Concerning fluid rewards, the osmolality level, one of the physiological indices for the level of thirst, may be an internal variable for valuation, since an increase in the osmolality level induces drinking behavior. Here, to examine the relationship between osmolality and the motivational value of a water reward, we repeatedly measured the blood osmolality level, while 2 monkeys continuously performed an instrumental task until they spontaneously stopped. We found that, as the total amount of water earned increased, the osmolality level progressively decreased (i.e., the hydration level increased) in an individual-dependent manner. There was a significant negative correlation between the error rate of the task (the proportion of trials with low motivation) and the osmolality level. We also found that the increase in the error rate with reward accumulation can be well explained by a formula describing the changes in the osmolality level. These results provide a biologically supported computational formula for the motivational value of a water reward that depends on the hydration level, enabling us to identify the neural mechanism that integrates internal and external variables.

A Workshop on High Energy Astrophysical for Amateur Astronomers

NASA Technical Reports Server (NTRS)

Fishman, Gerald J.; Mattei, J. A.; Rose, M. Franklin (Technical Monitor)

2000-01-01

Amateur astronomers are, in general, an enthusiastic and dynamic group of individuals who can help greatly in astronomy public outreach and education programs. In the U.S., they outnumber professional astronomers by over a factor of ten. Over eighty amateur astronomers from all over the U.S. and abroad attended a unique workshop in Huntsville, Alabama in April of this year. Most attendees were provided with travel grants under the condition that they disseminate knowledge gained at the workshop to civic groups, astronomy clubs and science teacher groups in their home communities. Twelve lecturers were given over two days, primarily by active high-energy researchers from NASA-MSFC and NASA-GSFC. Funding for the workshop was provided by a variety of NASA-sponsored projects, offices within OSS and private funding sources. The workshop attendees were selected by the AAVSO, which also administered the funding for the workshop. This high-leverage educational and public outreach program was deemed to be highly successful and bodes well for similar, future workshops. Many of the participants have already begun to give public talks on HEA and GRBs.

THREE FUNDAMENTAL PERIODS IN AN 87 YEAR LIGHT CURVE OF THE SYMBIOTIC STAR MWC 560

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leibowitz, Elia M.; Formiggini, Liliana, E-mail: elia@astro.tau.ac.il

2015-08-15

We construct a visual light curve of the symbiotic star MWC covering the last 87 years of its history. The data were assembled from the literature and from the AAVSO data bank. Most of the periodic components of the system brightness variation can be accounted for by the operation of three basic clocks of the periods P1 = 19,000 days, P2 = 1943 days, and P3 = 722 days. These periods can plausibly, and consistently with the observations, be attributed to three physical mechanisms in the system: the working of a solar-like magnetic dynamo cycle in the outer layers ofmore » the giant star of the system, the binary orbit cycle, and the sidereal rotation cycle of the giant star. MWC 560 is the seventh symbiotic star with historical light curves that reveal similar basic characteristics of the systems. The light curves of all these stars are well interpreted on the basis of the current understanding of the physical processes that are the major sources of the optical luminosity of these symbiotic systems.« less

URAT South Parallax Results

NASA Astrophysics Data System (ADS)

Finch, Charlie T.; Zacharias, Norbert; Jao, Wei-Chun

2018-04-01

We present 916 trigonometric parallaxes and proper motions of newly discovered nearby stars from the United States Naval Observatory Robotic Astrometric Telescope (URAT). Observations were taken at the Cerro Tololo Interamerican Observatory over a 2-year period from 2015 to 2017 October covering the entire sky south of about +25° decl. SPM4 and UCAC4 early epoch catalog data were added to extend the temporal coverage for the parallax and proper motion fit up to 48 years. Using these new URAT parallaxes, optical and near-IR photometry from the AAVSO Photometric All-Sky Survey and Two Micron All-Sky Survey catalogs, we identify possible new nearby dwarfs, young stars, low-metallicity subdwarfs and white dwarfs. Comparison to known trigonometric parallaxes shows a high quality of the URAT-based results confirming the error in parallax of the URAT south parallaxes reported here to be between 2 and 13 mas. We also include additional 729 trigonometric parallaxes from the URAT north 25 pc sample published in Finch & Zacharias here after applying the same criterion as for the southern sample to have a complete URAT 25 pc sample presented in this paper.

Simultaneous IUE and Ground Based Observations of SS Cygni and HL Canis Majoris

NASA Astrophysics Data System (ADS)

Mansperger, C. S.; Kaitchuck, R. H.; Garnavich, P.; Dinshaw, N.

1993-05-01

SS Cyg and HL CMa were observed by IUE for three consecutive nights in November of 1992. During the first two nights, simultaneous photometric ground based observations of SS Cyg were made at the Ball State University Observatory. SS Cyg and HL CMa were observed simultaneously with the 90-inch telescope at the Steward Observatory on the last two nights of this run. These spectroscopic observations covered the wavelength range of 4100 Angstroms to 5000 Angstroms, while the spectra taken with the short wavelength camera on IUE resulted in wavelength coverage from 1150 Angstroms to 1980 Angstroms. SS Cyg is a U Gem type dwarf nova with an orbital period of 6.6 hours. Good simultaneous UV and optical orbital coverage was obtained for this system. HL CMa is a Z Cam type dwarf nova with an outburst period of 18 days. The AAVSO reports that this system was in outburst 4 days after the observing run. Therefore, HL CMa may have been in a preoutburst state during these observations. The C IV and H \\beta emission lines appeared to have weakened during this time.

APASS Data Release 10

NASA Astrophysics Data System (ADS)

Henden, Arne A.; Levine, Stephen; Terrell, Dirk; Welch, Douglas L.; Munari, Ulisse; Kloppenborg, Brian K.

2018-06-01

The AAVSO Photometric All-Sky Survey (APASS) has been underway since 2010. This survey covers the entire sky from 7.5 < V < 16.5 magnitude, and in the BVugrizY bandpasses. A northern and a southern site are used, each with twin ASA 20cm astrographs and Apogee Aspen CG16m cameras, covering 2.9x2.9 square degrees with 2.6arcsec pixels. Landolt and SDSS standards are used for all-sky solutions, with typical 0.02mag calibration errors on the bright end. DR9 is currently available through VizieR. DR10 is a complete reprocessing of all 500K images taken with the system, including hundreds of nights not part of DR9. Sextractor is used for star finding and centroiding; DAOPHOT is used for aperture photometry; the astrometry.net plate-solving library is used for basic astrometry, supplanted with more precise WCS that utilizes knowledge of the optical train distortions. With these changes, DR10 includes many more stars than prior releases. We describe the survey, its remaining limitations, and prospects for the future, including a very-bright-star extension.

Nova Eruptions from Radio to Gamma-raysówith AAVSO Data in the Middle (Abstract)

NASA Astrophysics Data System (ADS)

Mukai, K.; Kafka, S.; Chomiuk, L.; Li, R.; Finzell, T.; Linford, J.; Sokoloski, J.; Nelson, T.; Rupen, M.; Mioduszewski, A.; Weston, J.

2018-06-01

(Abstract only) Novae are among the longest-known class of optical transients. In recent years, V1369 Cen in the south reached magnitude 3.3 in late 2013, and had repeated (but not periodic) cycles of re-brightening. Earlier in 2013, V339 Del almost reached magnitude 4.0 during the northern summer. An expanding ball of gas, at about 10,000 K, expelled by a nuclear explosion on the surface of a white dwarf, can explain much of the visible light outputs of novae. But these spectacular visible light displays turn out to be just a small part of the show. Novae are also transient objects in the radio through gamma-raysóin addition to the warm, visible light-emitting gas, we need cold dust particles that emit in the infra-red, 10 million degree shock-heated gas that emits hard X-rays, and the exposed surface of the nuclear-burning white dwarf that emits soft X-rays. Last but not least, we need an exotic process of particle acceleration to explain the gamma-rays and some radio data.

Developing Passenger Demand Models for International Aviation from/to Egypt: A Case Study of Cairo Airport and Egyptair

NASA Technical Reports Server (NTRS)

Abbas, Khaled A.; Fattah, Nabil Abdel; Reda, Hala R.

2003-01-01

This research is concerned with developing passenger demand models for international aviation from/to Egypt. In this context, aviation sector in Egypt is represented by the biggest and main airport namely Cairo airport as well as by the main Egyptian international air carrier namely Egyptair. The developed models utilize two variables to represent aviation demand, namely total number of international flights originating from and attracted to Cairo airport as well as total number of passengers using Egyptair international flights originating from and attracted to Cairo airport. Such demand variables were related, using different functional forms, to several explanatory variables including population, GDP and number of foreign tourists. Finally, two models were selected based on their logical acceptability, best fit and statistical significance. To demonstrate usefulness of developed models, these were used to forecast future demand patterns.

Intraspecific ITS Variability in the Kingdom Fungi as Expressed in the International Sequence Databases and Its Implications for Molecular Species Identification

PubMed Central

Nilsson, R. Henrik; Kristiansson, Erik; Ryberg, Martin; Hallenberg, Nils; Larsson, Karl-Henrik

2008-01-01

The internal transcribed spacer (ITS) region of the nuclear ribosomal repeat unit is the most popular locus for species identification and subgeneric phylogenetic inference in sequence-based mycological research. The region is known to show certain variability even within species, although its intraspecific variability is often held to be limited and clearly separated from interspecific variability. The existence of such a divide between intra- and interspecific variability is implicitly assumed by automated approaches to species identification, but whether intraspecific variability indeed is negligible within the fungal kingdom remains contentious. The present study estimates the intraspecific ITS variability in all fungi presently available to the mycological community through the international sequence databases. Substantial differences were found within the kingdom, and the results are not easily correlated to the taxonomic affiliation or nutritional mode of the taxa considered. No single unifying yet stringent upper limit for intraspecific variability, such as the canonical 3% threshold, appears to be applicable with the desired outcome throughout the fungi. Our results caution against simplified approaches to automated ITS-based species delimitation and reiterate the need for taxonomic expertise in the translation of sequence data into species names. PMID:19204817

Internal and International Mobility as Adaptation to Climatic Variability in Contemporary Mexico: Evidence from the Integration of Census and Satellite Data.

PubMed

Leyk, Stefan; Runfola, Dan; Nawrotzki, Raphael J; Hunter, Lori M; Riosmena, Fernando

2017-08-01

Migration provides a strategy for rural Mexican households to cope with, or adapt to, weather events and climatic variability. Yet prior studies on "environmental migration" in this context have not examined the differences between choices of internal (domestic) or international movement. In addition, much of the prior work relied on very coarse spatial scales to operationalize the environmental variables such as rainfall patterns. To overcome these limitations, we use fine-grain rainfall estimates derived from NASA's Tropical Rainfall Measuring Mission (TRMM) satellite. The rainfall estimates are combined with Population and Agricultural Census information to examine associations between environmental changes and municipal rates of internal and international migration 2005-2010. Our findings suggest that municipal-level rainfall deficits relative to historical levels are an important predictor of both international and internal migration, especially in areas dependent on seasonal rainfall for crop productivity. Although our findings do not contradict results of prior studies using coarse spatial resolution, they offer clearer results and a more spatially nuanced examination of migration as related to social and environmental vulnerability and thus higher degrees of confidence.

Electrochemical state and internal variables estimation using a reduced-order physics-based model of a lithium-ion cell and an extended Kalman filter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stetzel, KD; Aldrich, LL; Trimboli, MS

2015-03-15

This paper addresses the problem of estimating the present value of electrochemical internal variables in a lithium-ion cell in real time, using readily available measurements of cell voltage, current, and temperature. The variables that can be estimated include any desired set of reaction flux and solid and electrolyte potentials and concentrations at any set of one-dimensional spatial locations, in addition to more standard quantities such as state of charge. The method uses an extended Kalman filter along with a one-dimensional physics-based reduced-order model of cell dynamics. Simulations show excellent and robust predictions having dependable error bounds for most internal variables.more » (C) 2014 Elsevier B.V. All rights reserved.« less

Viscoplasticity: A thermodynamic formulation

NASA Technical Reports Server (NTRS)

Freed, A. D.; Chaboche, J. L.

1989-01-01

A thermodynamic foundation using the concept of internal state variables is given for a general theory of viscoplasticity, as it applies to initially isotropic materials. Three fundamental internal state variables are admitted. They are: a tensor valued back stress for kinematic effects, and the scalar valued drag and yield strengths for isotropic effects. All three are considered to phenomenologically evolve according to competitive processes between strain hardening, strain induced dynamic recovery, and time induced static recovery. Within this phenomenological framework, a thermodynamically admissible set of evolution equations is put forth. This theory allows each of the three fundamental internal variables to be composed as a sum of independently evolving constituents.

International students' enrollment in IPTA by using multilevel analysis

NASA Astrophysics Data System (ADS)

Wai, Phoong Seuk; Ismail, Mohd Tahir; Karim, Samsul Ariffin Abdul

2012-09-01

The increases of demand on knowledge-based and production-based market force the growth of higher education. International students' enrollment contributes to economic growth and increase country's income, university reputation and name; promote the competitive of education and training markets. This paper used multilevel analysis to study the international students' enrollment in Malaysia public university. Student's background variables and institution background variables were study in this paper and the relationship among them also been investigated. Result shows that institution type is a significance factor on international students' enrollment in Malaysia public university.

The Interplay of Internal and Forced Modes of Hadley Cell Expansion: Lessons from the Global Warming Hiatus

NASA Astrophysics Data System (ADS)

Amaya, D. J.; Siler, N.; Xie, S. P.; Miller, A. J.

2017-12-01

The poleward branches of the Hadley Cells show a robust shift poleward shift during the satellite era, leading to concerns over the possible encroachment of the globe's subtropical dry zones into currently temperate climates. The extent to which this trend is caused by anthropogenic forcing versus internal variability remains the subject of considerable debate. In this study, we us a joint EOF method to identify two distinct modes of Hadley Cell variability: (i) an anthropogenically-forced mode, which we identify using a 20-member simulation of the historical climate, and (ii) an internal mode, which identify using a 1000-year pre-industrial control simulation with a global climate model. The forced mode is found to be closely related to the TOA radiative imbalance and exhibits a long-term trend since 1860, while the internal mode is found to be essentially indistinguishable from the El Niño Southern Oscillation (ENSO). Together these two modes explain an average of 70% of the interannual variability seen in model "edge indices" over the historical period. Since 1980, the superposition of forced and internal modes has resulted in a period of accelerated Hadley Cell expansion and decelerated global warming (i.e., the "hiatus"). A comparison of the change in these modes since 1980 indicates that by 2013 the signal has emerged above the noise of internal variability in the Southern Hemisphere (SH), but not in the Northern Hemisphere (NH), with the latter also exhibiting strong zonal asymmetry, particularly in the North Atlantic. Our results highlight the important interplay of internal and forced modes of Hadley Cell width change and improve our understanding of the interannual variability and long-term trend seen in observations.

The interplay of internal and forced modes of Hadley Cell expansion: lessons from the global warming hiatus

NASA Astrophysics Data System (ADS)

Amaya, Dillon J.; Siler, Nicholas; Xie, Shang-Ping; Miller, Arthur J.

2017-09-01

The poleward branches of the Hadley Cells and the edge of the tropics show a robust poleward shift during the satellite era, leading to concerns over the possible encroachment of the globe's subtropical dry zones into currently temperate climates. The extent to which this trend is caused by anthropogenic forcing versus internal variability remains the subject of considerable debate. In this study, we use a Joint EOF method to identify two distinct modes of tropical width variability: (1) an anthropogenically-forced mode, which we identify using a 20-member simulation of the historical climate, and (2) an internal mode, which we identify using a 1000-year pre-industrial control simulation. The forced mode is found to be closely related to the top of the atmosphere radiative imbalance and exhibits a long-term trend since 1860, while the internal mode is essentially indistinguishable from the El Niño Southern Oscillation. Together these two modes explain an average of 70% of the interannual variability seen in model "edge indices" over the historical period. Since 1980, the superposition of forced and internal modes has resulted in a period of accelerated Hadley Cell expansion and decelerated global warming (i.e., the "hiatus"). A comparison of the change in these modes since 1980 indicates that by 2013 the signal has emerged above the noise of internal variability in the Southern Hemisphere, but not in the Northern Hemisphere, with the latter also exhibiting strong zonal asymmetry, particularly in the North Atlantic. Our results highlight the important interplay of internal and forced modes of tropical width change and improve our understanding of the interannual variability and long-term trend seen in observations.

Child Internalizing Symptoms: Contributions of Child Temperament, Maternal Negative Affect, and Family Functioning

ERIC Educational Resources Information Center

Crawford, Nicole A.; Schrock, Matthew; Woodruff-Borden, Janet

2011-01-01

Research has traditionally focused on the role of genetic and environmental variables in the development and maintenance of childhood internalizing disorders. Temperament variables, such as negative affect and effortful control have gained considerable interest within the field of developmental psychopathology. Environmental factors such as…

International urodynamic basic spinal cord injury data set.

PubMed

Biering-Sørensen, F; Craggs, M; Kennelly, M; Schick, E; Wyndaele, J-J

2008-07-01

To create the International Urodynamic Basic Spinal Cord Injury (SCI) Data Set within the framework of the International SCI Data Sets. International working group. The draft of the data set was developed by a working group consisting of members appointed by the Neurourology Committee of the International Continence Society, the European Association of Urology, the American Spinal Injury Association (ASIA), the International Spinal Cord Society (ISCoS) and a representative of the Executive Committee of the International SCI Standards and Data Sets. The final version of the data set was developed after review and comments by members of the Executive Committee of the International SCI Standards and Data Sets, the ISCoS Scientific Committee, ASIA Board, relevant and interested (international) organizations and societies (around 40) and persons and the ISCoS Council. Endorsement of the data set by relevant organizations and societies will be obtained. To make the data set uniform, each variable and each response category within each variable have been specifically defined in a way that is designed to promote the collection and reporting of comparable minimal data. Variables included in the International Urodynamic Basic SCI Data Set are date of data collection, bladder sensation during filling cystometry, detrusor function, compliance during filing cystometry, function during voiding, detrusor leak point pressure, maximum detrusor pressure, cystometric bladder capacity and post-void residual volume.

The Role of Individual Differences and Situational Variables in the Use of Workplace Sexual Identity Management Strategies.

PubMed

Reed, Louren; Leuty, Melanie E

2016-07-01

Examination of individual difference variables have been largely ignored within research on the use of workplace sexual identity management strategies. The current study examined personality traits (extraversion, openness, and neuroticism), facets of sexual identity development (identity confusion, internalized heterosexism), and situational variables (e.g., perceptions of workplace climate and heterosexism) in explaining the use of management strategies, as well as possible interactions between individual and situational factors. Perceptions of the workplace climate toward lesbian and gay individuals significantly related to the use each of the management strategies, and Internalized Heterosexism was found to significantly predict the use of the Explicitly Out strategy. Most interactions between individual difference and situational variables were not supported, with the exception of an interaction between workplace heterosexism and internalized homophobia in explaining the use of the Explicitly Out strategy.

Internalized HIV Stigma and Disclosure Concerns: Development and Validation of Two Scales in Spanish-Speaking Populations.

PubMed

Hernansaiz-Garrido, Helena; Alonso-Tapia, Jesús

2017-01-01

Internalized stigma and disclosure concerns are key elements for the study of mental health in people living with HIV. Since no measures of these constructs were available for Spanish population, this study sought to develop such instruments, to analyze their reliability and validity and to provide a short version. A heterogeneous sample of 458 adults from different Spanish-speaking countries completed the HIV-Internalized Stigma Scale and the HIV-Disclosure Concerns Scale, along with the Hospital Anxiety and Depression Scale, Rosenberg's Self-esteem Scale and other socio-demographic variables. Reliability and correlation analyses, exploratory factor analyses, path analyses with latent variables, and ANOVAs were conducted to test the scales' psychometric properties. The scales showed good reliability in terms of internal consistency and temporal stability, as well as good sensitivity and factorial and criterion validity. The HIV-Internalized Stigma Scale and the HIV-Disclosure Concerns Scale are reliable and valid means to assess these variables in several contexts.

Nonlinear Internal Waves on the Inner Shelf: Observations Using a Distributed Temperature Sensing (DTS) System.

NASA Astrophysics Data System (ADS)

Davis, K. A.; Reid, E. C.; Cohen, A. L.

2016-02-01

Internal waves propagating across the continental slope and shelf are transformed by the competing effects of nonlinear steepening and dispersive spreading, forming nonlinear internal waves (NLIWs) that can penetrate onto the shallow inner shelf, often appearing in the form of bottom-propagating nonlinear internal bores or boluses. NLIWs play a significant role in nearshore dynamics with baroclinic current amplitudes on the order of that of wind- and surface wave-driven flows and rapid temperature changes on the order of annual ranges. In June 2014 we used a Distributed Temperature Sensing (DTS) system to give a continuous cross-shelf view of nonlinear internal wave dynamics on the forereef of Dongsha Atoll, a coral reef in the northern South China Sea. A DTS system measures temperature continuously along the length of an optical fiber, resolving meter-to-kilometer spatial scales. This unique view of cross-shelf temperature structure made it possible to observe internal wave reflection, variable propagation speed across the shelf, bolus formation and dissipation. Additionally, we used the DTS data to track internal waves across the shallow fore reef and onto the reef flat and to quantify spatial patterns in temperature variability. Shoaling internal waves are an important process affecting physical variability and water properties on the reef.

Development of lifetime comorbidity in the WHO World Mental Health (WMH) Surveys

PubMed Central

Kessler, Ronald C.; Ormel, Johan; Petukhova, Maria; McLaughlin, Katie A.; Green, Jennifer Greif; Russo, Leo J.; Stein, Dan J.; Zaslavsky, Alan M; Aguilar-Gaxiola, Sergio; Alonso, Jordi; Andrade, Laura; Benjet, Corina; de Girolamo, Giovanni; de Graaf, Ron; Demyttenaere, Koen; Fayyad, John; Haro, Josep Maria; Hu, Chi yi; Karam, Aimee; Lee, Sing; Lepine, Jean-Pierre; Matchsinger, Herbert; Mihaescu-Pintia, Constanta; Posada-Villa, Jose; Sagar, Rajesh; Üstün, T. Bedirhan

2010-01-01

CONTEXT Although numerous studies have examined the role of latent variables in the structure of comorbidity among mental disorders, none has examined their role in the development of comorbidity. OBJECTIVE To study the role of latent variables in the development of comorbidity among 18 lifetime DSM-IV disorders in the WHO World Mental Health (WMH) surveys. SETTING/PARTICIPANTS Nationally or regionally representative community surveys in 14 countries with a total of 21,229 respondents. MAIN OUTCOME MEASURES First onset of 18 lifetime DSM-IV anxiety, mood, behavior, and substance disorders assessed retrospectively in the WHO Composite International Diagnostic Interview (CIDI). RESULTS Separate internalizing (anxiety and mood disorders) and externalizing (behavior and substance disorders) factors were found in exploratory factor analysis of lifetime disorders. Consistently significant positive time-lagged associations were found in survival analyses for virtually all temporally primary lifetime disorders predicting subsequent onset of other disorders. Within-domain (i.e., internalizing or externalizing) associations were generally stronger than between-domain associations. The vast majority of time-lagged associations were explained by a model that assumed the existence of mediating latent internalizing and externalizing variables. Specific phobia and obsessive-compulsive disorder (internalizing) and hyperactivity disorder and oppositional-defiant disorder (externalizing) were the most important predictors. A small number of residual associations remained significant after controlling the latent variables. CONCLUSIONS The good fit of the latent variable model suggests that common causal pathways account for most of the comorbidity among the disorders considered here. These common pathways should be the focus of future research on the development of comorbidity, although several important pair-wise associations that cannot be accounted for by latent variables also exist that warrant further focused study. PMID:21199968

Decadal predictions of Southern Ocean sea ice : testing different initialization methods with an Earth-system Model of Intermediate Complexity

NASA Astrophysics Data System (ADS)

Zunz, Violette; Goosse, Hugues; Dubinkina, Svetlana

2013-04-01

The sea ice extent in the Southern Ocean has increased since 1979 but the causes of this expansion have not been firmly identified. In particular, the contribution of internal variability and external forcing to this positive trend has not been fully established. In this region, the lack of observations and the overestimation of internal variability of the sea ice by contemporary General Circulation Models (GCMs) make it difficult to understand the behaviour of the sea ice. Nevertheless, if its evolution is governed by the internal variability of the system and if this internal variability is in some way predictable, a suitable initialization method should lead to simulations results that better fit the reality. Current GCMs decadal predictions are generally initialized through a nudging towards some observed fields. This relatively simple method does not seem to be appropriated to the initialization of sea ice in the Southern Ocean. The present study aims at identifying an initialization method that could improve the quality of the predictions of Southern Ocean sea ice at decadal timescales. We use LOVECLIM, an Earth-system Model of Intermediate Complexity that allows us to perform, within a reasonable computational time, the large amount of simulations required to test systematically different initialization procedures. These involve three data assimilation methods: a nudging, a particle filter and an efficient particle filter. In a first step, simulations are performed in an idealized framework, i.e. data from a reference simulation of LOVECLIM are used instead of observations, herein after called pseudo-observations. In this configuration, the internal variability of the model obviously agrees with the one of the pseudo-observations. This allows us to get rid of the issues related to the overestimation of the internal variability by models compared to the observed one. This way, we can work out a suitable methodology to assess the efficiency of the initialization procedures tested. It also allows us determine the upper limit of improvement that can be expected if more sophisticated initialization methods are used in decadal prediction simulations and if models have an internal variability agreeing with the observed one. Furthermore, since pseudo-observations are available everywhere at any time step, we also analyse the differences between simulations initialized with a complete dataset of pseudo-observations and the ones for which pseudo-observations data are not assimilated everywhere. In a second step, simulations are realized in a realistic framework, i.e. through the use of actual available observations. The same data assimilation methods are tested in order to check if more sophisticated methods can improve the reliability and the accuracy of decadal prediction simulations, even if they are performed with models that overestimate the internal variability of the sea ice extent in the Southern Ocean.

The Prediction of Labor Force Status: Implications from International Adult Skill Assessments. Research Report. ETS RR-16-11

ERIC Educational Resources Information Center

Li, Tongyun; von Davier, Matthias; Hancock, Gregory R.

2016-01-01

This report investigates the prediction of labor force status using observed variables, such as gender, age, and immigrant status, and more importantly, measured skill variables, including literacy proficiency and a categorical rating of educational attainment based on the 1994 International Adult Literacy Survey (IALS), the 2003 Adult Literacy…

A Study of Resiliency Characteristics in the Adjustment of International Graduate Students at American Universities

ERIC Educational Resources Information Center

Wang, Jing

2009-01-01

This research introduced the concept of resilience into the study of adjustment of international graduate students at U.S. universities. The purpose of this study was to explore relationships among resilience characteristics, background variables, and adjustment problem areas, and to gauge the effects of resilience and background variables on…

Static internal performance of single-expansion-ramp nozzles with various combinations of internal geometric parameters

NASA Technical Reports Server (NTRS)

Re, R. J.; Leavitt, L. D.

1984-01-01

The effects of five geometric design parameters on the internal performance of single-expansion-ramp nozzles were investigated at nozzle pressure ratios up to 10 in the static-test facility of the Langley 16-Foot Transonic Tunnel. The geometric variables on the expansion-ramp surface of the upper flap consisted of ramp chordal angle, ramp length, and initial ramp angle. On the lower flap, the geometric variables consisted of flap angle and flap length. Both internal performance and static-pressure distributions on the centerlines of the upper and lower flaps were obtained for all 43 nozzle configurations tested.

The Sun as a variable star: Solar and stellar irradiance variations; Colloquium of the International Astronomical Union, 143rd, Boulder, CO, Jun. 20-25, 1993

NASA Technical Reports Server (NTRS)

Pap, Judit M. (Editor); Froehlich, Claus (Editor); Hudson, Hugh S. (Editor); Tobiska, W. Kent (Editor)

1994-01-01

Variations in solar and stellar irradiances have long been of interest. An International Astronomical Union (IAU) colloquium reviewed such relevant subjects as observations, theoretical interpretations, and empirical and physical models, with a special emphasis on climatic impact of solar irradiance variability. Specific topics discussed included: (1) General Reviews on Observations of Solar and Stellar Irradiance Variability; (2) Observational Programs for Solar and Stellar Irradiance Variability; (3) Variability of Solar and Stellar Irradiance Related to the Network, Active Regions (Sunspots and Plages), and Large-Scale Magnetic Structures; (4) Empirical Models of Solar Total and Spectral Irradiance Variability; (5) Solar and Stellar Oscillations, Irradiance Variations and their Interpretations; and (6) The Response of the Earth's Atmosphere to Solar Irradiance Variations and Sun-Climate Connections.

Local-scale changes in mean and heavy precipitation in Western Europe, climate change or internal variability?

NASA Astrophysics Data System (ADS)

Aalbers, Emma E.; Lenderink, Geert; van Meijgaard, Erik; van den Hurk, Bart J. J. M.

2018-06-01

High-resolution climate information provided by e.g. regional climate models (RCMs) is valuable for exploring the changing weather under global warming, and assessing the local impact of climate change. While there is generally more confidence in the representativeness of simulated processes at higher resolutions, internal variability of the climate system—`noise', intrinsic to the chaotic nature of atmospheric and oceanic processes—is larger at smaller spatial scales as well, limiting the predictability of the climate signal. To quantify the internal variability and robustly estimate the climate signal, large initial-condition ensembles of climate simulations conducted with a single model provide essential information. We analyze a regional downscaling of a 16-member initial-condition ensemble over western Europe and the Alps at 0.11° resolution, similar to the highest resolution EURO-CORDEX simulations. We examine the strength of the forced climate response (signal) in mean and extreme daily precipitation with respect to noise due to internal variability, and find robust small-scale geographical features in the forced response, indicating regional differences in changes in the probability of events. However, individual ensemble members provide only limited information on the forced climate response, even for high levels of global warming. Although the results are based on a single RCM-GCM chain, we believe that they have general value in providing insight in the fraction of the uncertainty in high-resolution climate information that is irreducible, and can assist in the correct interpretation of fine-scale information in multi-model ensembles in terms of a forced response and noise due to internal variability.

Influence of internal variability on population exposure to hydroclimatic changes

NASA Astrophysics Data System (ADS)

Mankin, Justin S.; Viviroli, Daniel; Mekonnen, Mesfin M.; Hoekstra, Arjen Y.; Horton, Radley M.; E Smerdon, Jason; Diffenbaugh, Noah S.

2017-04-01

Future freshwater supply, human water demand, and people’s exposure to water stress are subject to multiple sources of uncertainty, including unknown future pathways of fossil fuel and water consumption, and ‘irreducible’ uncertainty arising from internal climate system variability. Such internal variability can conceal forced hydroclimatic changes on multi-decadal timescales and near-continental spatial-scales. Using three projections of population growth, a large ensemble from a single Earth system model, and assuming stationary per capita water consumption, we quantify the likelihoods of future population exposure to increased hydroclimatic deficits, which we define as the average duration and magnitude by which evapotranspiration exceeds precipitation in a basin. We calculate that by 2060, ∽31%-35% of the global population will be exposed to >50% probability of hydroclimatic deficit increases that exceed existing hydrological storage, with up to 9% of people exposed to >90% probability. However, internal variability, which is an irreducible uncertainty in climate model predictions that is under-sampled in water resource projections, creates substantial uncertainty in predicted exposure: ∽86%-91% of people will reside where irreducible uncertainty spans the potential for both increases and decreases in sub-annual water deficits. In one population scenario, changes in exposure to large hydroclimate deficits vary from -3% to +6% of global population, a range arising entirely from internal variability. The uncertainty in risk arising from irreducible uncertainty in the precise pattern of hydroclimatic change, which is typically conflated with other uncertainties in projections, is critical for climate risk management that seeks to optimize adaptations that are robust to the full set of potential real-world outcomes.

Local-scale changes in mean and heavy precipitation in Western Europe, climate change or internal variability?

NASA Astrophysics Data System (ADS)

Aalbers, Emma E.; Lenderink, Geert; van Meijgaard, Erik; van den Hurk, Bart J. J. M.

2017-09-01

High-resolution climate information provided by e.g. regional climate models (RCMs) is valuable for exploring the changing weather under global warming, and assessing the local impact of climate change. While there is generally more confidence in the representativeness of simulated processes at higher resolutions, internal variability of the climate system—`noise', intrinsic to the chaotic nature of atmospheric and oceanic processes—is larger at smaller spatial scales as well, limiting the predictability of the climate signal. To quantify the internal variability and robustly estimate the climate signal, large initial-condition ensembles of climate simulations conducted with a single model provide essential information. We analyze a regional downscaling of a 16-member initial-condition ensemble over western Europe and the Alps at 0.11° resolution, similar to the highest resolution EURO-CORDEX simulations. We examine the strength of the forced climate response (signal) in mean and extreme daily precipitation with respect to noise due to internal variability, and find robust small-scale geographical features in the forced response, indicating regional differences in changes in the probability of events. However, individual ensemble members provide only limited information on the forced climate response, even for high levels of global warming. Although the results are based on a single RCM-GCM chain, we believe that they have general value in providing insight in the fraction of the uncertainty in high-resolution climate information that is irreducible, and can assist in the correct interpretation of fine-scale information in multi-model ensembles in terms of a forced response and noise due to internal variability.

An Analysis of Freight Forwarder Operations in an International Distribution Channel.

DTIC Science & Technology

1987-01-01

44 3. International Marketing Mix ....................... 45 4. Security Assistance Distribution Channel .......... 69 5...an item is ultimately derived from the interaction of variables in the marketing mix . Of those variables, the distribution functions seem to allow the...Component of the Marketing Mix ,"Proceedings, NCPDM Fall Meeting, National council of Physical Distribution Management, San Francisco, CA., 1982. 7

An Analysis of Basic Construction Variables of Racing Wheelchairs Used in the 1984 International Games for the Disabled.

ERIC Educational Resources Information Center

York, Sherril L.; Kimura, Iris F.

1987-01-01

A photographic analysis of racing wheelchairs used by cerebral palsy class four athletes and amputee athletes at the 1984 International Games for the Disabled was undertaken in order to analyze seven wheelchair construction variables in relation to performance outcome, distance raced, and type of disability of the user. (Author/MT)

Nonlinear waves in solids with slow dynamics: an internal-variable model.

PubMed

Berjamin, H; Favrie, N; Lombard, B; Chiavassa, G

2017-05-01

In heterogeneous solids such as rocks and concrete, the speed of sound diminishes with the strain amplitude of a dynamic loading (softening). This decrease, known as 'slow dynamics', occurs at time scales larger than the period of the forcing. Also, hysteresis is observed in the steady-state response. The phenomenological model by Vakhnenko et al. (2004 Phys. Rev. E 70, 015602. (doi:10.1103/PhysRevE.70.015602)) is based on a variable that describes the softening of the material. However, this model is one dimensional and it is not thermodynamically admissible. In the present article, a three-dimensional model is derived in the framework of the finite-strain theory. An internal variable that describes the softening of the material is introduced, as well as an expression of the specific internal energy. A mechanical constitutive law is deduced from the Clausius-Duhem inequality. Moreover, a family of evolution equations for the internal variable is proposed. Here, an evolution equation with one relaxation time is chosen. By construction, this new model of the continuum is thermodynamically admissible and dissipative (inelastic). In the case of small uniaxial deformations, it is shown analytically that the model reproduces qualitatively the main features of real experiments.

Internal Waves in the East Australian Current

NASA Astrophysics Data System (ADS)

Alford, Matthew H.; Sloyan, Bernadette M.; Simmons, Harper L.

2017-12-01

Internal waves, which drive most ocean turbulence and add "noise" to lower-frequency records, interact with low-frequency current systems and topography in yet poorly known ways. Taking advantage of a heavily instrumented, 14 month mooring array, internal waves in the East Australian Current (EAC) are examined for the first time. Internal wave horizontal kinetic energy (HKE) is within a factor of 2 of the Garrett-Munk (1976) spectrum. Continuum internal waves, near-inertial waves, and internal tides together constitute a significant percentage of the total velocity variance. Mode-1 internal tide energy fluxes are southward and much smaller than energy times group velocity, consistent with reflection at the continental slope of incident waves generated from near New Caledonia and the Solomon Islands. Internal tide HKE is highly phase variable, consistent with refraction by the variable EAC. Mode-1 near-inertial wave energy fluxes are of comparable magnitude and are equatorward and episodic, consistent with generation by storms farther poleward. These processes are considered together in the complex environment of the EAC.

International urinary tract imaging basic spinal cord injury data set.

PubMed

Biering-Sørensen, F; Craggs, M; Kennelly, M; Schick, E; Wyndaele, J-J

2009-05-01

To create an International Urinary Tract Imaging Basic Spinal Cord Injury (SCI) Data Set within the framework of the International SCI Data Sets. An international working group. The draft of the Data Set was developed by a working group comprising members appointed by the Neurourology Committee of the International Continence Society, the European Association of Urology, the American Spinal Injury Association (ASIA), the International Spinal Cord Society (ISCoS) and a representative of the Executive Committee of the International SCI Standards and Data Sets. The final version of the Data Set was developed after review and comments by members of the Executive Committee of the International SCI Standards and Data Sets, the ISCoS Scientific Committee, ASIA Board, relevant and interested international organizations and societies (around 40), individual persons with specific expertise and the ISCoS Council. Endorsement of the Data Sets by relevant organizations and societies will be obtained. To make the Data Set uniform, each variable and each response category within each variable have been specifically defined in a way that is designed to promote the collection and reporting of comparable minimal data. The variables included in the International Urinary Tract Imaging Basic SCI Data Set are the results obtained using the following investigations: intravenous pyelography or computer tomography urogram or ultrasound, X-ray, renography, clearance, cystogram, voiding cystogram or micturition cystourogram or videourodynamics. The complete instructions for data collection and the data sheet itself are freely available on the websites of both ISCoS (http://www.iscos.org.uk) and ASIA (http://www.asia-spinalinjury.org).

Conditional Mediation of Absorptive Capacity and Environment in International Entrepreneurial Orientation of Family Businesses

PubMed Central

Hernández-Perlines, Felipe; Xu, Wenkai

2018-01-01

This study analyzes the effect of conditional mediation of environment-absorptive capacity in international entrepreneurial orientation of family businesses. Results involve data from 218 Spanish family businesses, analyzed with SmartPLS 3.2.7 software. This paper presents a relevant contribution both to the academic field and the performance of family firms, helping to understand the process of transforming international entrepreneurial orientation into a better international performance through absorptive capacity while family businesses invest their efforts in aligning international entrepreneurial orientation and absorptive capacity with international results, bearing in mind the positive moderator effect of environment. The most relevant contribution of this work is to integrate in the same model the mediating effect of the absorption capacity and the moderating effect of the environment: the effect of the international entrepreneurial orientation on the international performance of family businesses improves with the mediation of the absorptive capacity (the variability of international performance goes from 32.5 to 40.6%) and the moderation of the environment (to variability of international performance goes from 40.6 to 45.3%). PMID:29472881

Conditional Mediation of Absorptive Capacity and Environment in International Entrepreneurial Orientation of Family Businesses.

PubMed

Hernández-Perlines, Felipe; Xu, Wenkai

2018-01-01

This study analyzes the effect of conditional mediation of environment-absorptive capacity in international entrepreneurial orientation of family businesses. Results involve data from 218 Spanish family businesses, analyzed with SmartPLS 3.2.7 software. This paper presents a relevant contribution both to the academic field and the performance of family firms, helping to understand the process of transforming international entrepreneurial orientation into a better international performance through absorptive capacity while family businesses invest their efforts in aligning international entrepreneurial orientation and absorptive capacity with international results, bearing in mind the positive moderator effect of environment. The most relevant contribution of this work is to integrate in the same model the mediating effect of the absorption capacity and the moderating effect of the environment: the effect of the international entrepreneurial orientation on the international performance of family businesses improves with the mediation of the absorptive capacity (the variability of international performance goes from 32.5 to 40.6%) and the moderation of the environment (to variability of international performance goes from 40.6 to 45.3%).

Organizational adoption of preemployment drug testing.

PubMed

Spell, C S; Blum, T C

2001-04-01

This study explored the adoption of preemployment drug testing by 360 organizations. Survival models were developed that included internal organizational and labor market factors hypothesized to affect the likelihood of adoption of drug testing. Also considered was another set of variables that included social and political variables based on institutional theory. An event history analysis using Cox regressions indicated that both internal organizational and environmental variables predicted adoption of drug testing. Results indicate that the higher the proportion of drug testers in the worksite's industry, the more likely it would be to adopt drug testing. Also, the extent to which an organization uses an internal labor market, voluntary turnover rate, and the extent to which management perceives drugs to be a problem were related to likelihood of adoption of drug testing.

Predictions of Poisson's ratio in cross-ply laminates containing matrix cracks and delaminations

NASA Technical Reports Server (NTRS)

Harris, Charles E.; Allen, David H.; Nottorf, Eric W.

1989-01-01

A damage-dependent constitutive model for laminated composites has been developed for the combined damage modes of matrix cracks and delaminations. The model is based on the concept of continuum damage mechanics and uses second-order tensor valued internal state variables to represent each mode of damage. The internal state variables are defined as the local volume average of the relative crack face displacements. Since the local volume for delaminations is specified at the laminate level, the constitutive model takes the form of laminate analysis equations modified by the internal state variables. Model implementation is demonstrated for the laminate engineering modulus E(x) and Poisson's ratio nu(xy) of quasi-isotropic and cross-ply laminates. The model predictions are in close agreement to experimental results obtained for graphite/epoxy laminates.

Closed Loop Control of Automotive Engines

DOT National Transportation Integrated Search

1981-12-01

Internal combustion engine economy and emissions are known to be sensitive to changes in engine control variables. Two of the most important variables are fuel/air ratio (f/a) and spark advance. These variables are affected by environmental changes, ...

Prospects for a prolonged slowdown in global warming in the early 21st century

PubMed Central

Knutson, Thomas R.; Zhang, Rong; Horowitz, Larry W.

2016-01-01

Global mean temperature over 1998 to 2015 increased at a slower rate (0.1 K decade−1) compared with the ensemble mean (forced) warming rate projected by Coupled Model Intercomparison Project 5 (CMIP5) models (0.2 K decade−1). Here we investigate the prospects for this slower rate to persist for a decade or more. The slower rate could persist if the transient climate response is overestimated by CMIP5 models by a factor of two, as suggested by recent low-end estimates. Alternatively, using CMIP5 models' warming rate, the slower rate could still persist due to strong multidecadal internal variability cooling. Combining the CMIP5 ensemble warming rate with internal variability episodes from a single climate model—having the strongest multidecadal variability among CMIP5 models—we estimate that the warming slowdown (<0.1 K decade−1 trend beginning in 1998) could persist, due to internal variability cooling, through 2020, 2025 or 2030 with probabilities 16%, 11% and 6%, respectively. PMID:27901045

[Validation of a Japanese version of the Experience in Close Relationship- Relationship Structure].

PubMed

Komura, Kentaro; Murakami, Tatsuya; Toda, Koji

2016-08-01

The purpose of this study was to translate the Experience of Close Relationship-Relationship Structure (ECRRS) and evaluate its validity. In study 1 (N = 982), evidence based internal structure (factor structure, internal consistency, and correlation among sub-scales) and evidence based relations to other variables (depression, reassurance seeking and self-esteem) were confirmed. In study 2 (N = 563), evidence based on internal structure was reconfirmed, and evidence based relations to other variables (IWMS, RQ, and ECR-GO) were confirmed. In study 3 (N = 342), evidence based internal structure (test-retest reliability) was confirmed. Based on these results, we concluded that ECR-RS was valid for measuring adult attachment style.

A review of employment conditions as social determinants of health part II: the workplace.

PubMed

Moure-Eraso, Rafael; Flum, Marian; Lahiri, Supriya; Tilly, Chris; Massawe, Ephraim

2006-01-01

This is the second part of an article on employment conditions as social determinants of health and health inequalities. In part I of this article, we explored structural (external) employment conditions that affect health inequalities and health gradients. In this article, we try to examine the internal aspects of employment conditions that affect the same variables. It is not our intention to "box" employment conditions in a rigid framework within an internal domain of person-hazard interaction. The objective of examining this variable is to scrutinize internal aspects of employment conditions at a comprehensive policy level in conjunction with external contextual variables. Major occupational health concerns are examined in relationship to globalization, child labor, and work in the formal and informal sectors. Interventions that can eliminate or greatly reduce these exposures as well as those that have been unsuccessful are reviewed. Innovative interventions including work organization change, cleaner production, control banding, national and international coalitions, participatory training, and participatory approaches to improving the work environment are reviewed.

The Role of Individual and Social Variables in Predicting Body Dissatisfaction and Eating Disorder Symptoms among Iranian Adolescent Girls: An Expanding of the Tripartite Influence Mode.

PubMed

Shahyad, Shima; Pakdaman, Shahla; Shokri, Omid; Saadat, Seyed Hassan

2018-01-12

The aim of the present study was to examine the causal relationships between psychological and social factors, being independent variables and body image dissatisfaction plus symptoms of eating disorders as dependent variables through the mediation of social comparison and thin-ideal internalization. To conduct the study, 477 high-school students from Tehran were recruited by method of cluster sampling. Next, they filled out Rosenberg Self-esteem Scale (RSES), Physical Appearance Comparison Scale (PACS), Self-Concept Clarity Scale (SCCS), Appearance Perfectionism Scale (APS), Eating Disorder Inventory (EDI), Multidimensional Body Self Relations Questionnaire (MBSRQ) and Sociocultural Attitudes towards Appearance Questionnaire (SATAQ-4). In the end, collected data were analyzed using structural equation modeling. Findings showed that the assumed model perfectly fitted the data after modification and as a result, all the path-coefficients of latent variables (except for the path between self-esteem and thin-ideal internalization) were statistically significant (p>0.05). Also, in this model, 75% of scores' distribution of body dissatisfaction was explained through psychological variables, socio-cultural variables, social comparison and internalization of the thin ideal. The results of the present study provid experimental basis for the confirmation of proposed causal model. The combination of psychological, social and cultural variables could efficiently predict body image dissatisfaction of young girls in Iran.

Towards multi-resolution global climate modeling with ECHAM6-FESOM. Part II: climate variability

NASA Astrophysics Data System (ADS)

Rackow, T.; Goessling, H. F.; Jung, T.; Sidorenko, D.; Semmler, T.; Barbi, D.; Handorf, D.

2018-04-01

This study forms part II of two papers describing ECHAM6-FESOM, a newly established global climate model with a unique multi-resolution sea ice-ocean component. While part I deals with the model description and the mean climate state, here we examine the internal climate variability of the model under constant present-day (1990) conditions. We (1) assess the internal variations in the model in terms of objective variability performance indices, (2) analyze variations in global mean surface temperature and put them in context to variations in the observed record, with particular emphasis on the recent warming slowdown, (3) analyze and validate the most common atmospheric and oceanic variability patterns, (4) diagnose the potential predictability of various climate indices, and (5) put the multi-resolution approach to the test by comparing two setups that differ only in oceanic resolution in the equatorial belt, where one ocean mesh keeps the coarse 1° resolution applied in the adjacent open-ocean regions and the other mesh is gradually refined to 0.25°. Objective variability performance indices show that, in the considered setups, ECHAM6-FESOM performs overall favourably compared to five well-established climate models. Internal variations of the global mean surface temperature in the model are consistent with observed fluctuations and suggest that the recent warming slowdown can be explained as a once-in-one-hundred-years event caused by internal climate variability; periods of strong cooling in the model (`hiatus' analogs) are mainly associated with ENSO-related variability and to a lesser degree also to PDO shifts, with the AMO playing a minor role. Common atmospheric and oceanic variability patterns are simulated largely consistent with their real counterparts. Typical deficits also found in other models at similar resolutions remain, in particular too weak non-seasonal variability of SSTs over large parts of the ocean and episodic periods of almost absent deep-water formation in the Labrador Sea, resulting in overestimated North Atlantic SST variability. Concerning the influence of locally (isotropically) increased resolution, the ENSO pattern and index statistics improve significantly with higher resolution around the equator, illustrating the potential of the novel unstructured-mesh method for global climate modeling.

The role of internal climate variability for interpreting climate change scenarios

NASA Astrophysics Data System (ADS)

Maraun, Douglas

2013-04-01

When communicating information on climate change, the use of multi-model ensembles has been advocated to sample uncertainties over a range as wide as possible. To meet the demand for easily accessible results, the ensemble is often summarised by its multi-model mean signal. In rare cases, additional uncertainty measures are given to avoid loosing all information on the ensemble spread, e.g., the highest and lowest projected values. Such approaches, however, disregard the fundamentally different nature of the different types of uncertainties and might cause wrong interpretations and subsequently wrong decisions for adaptation. Whereas scenario and climate model uncertainties are of epistemic nature, i.e., caused by an in principle reducible lack of knowledge, uncertainties due to internal climate variability are aleatory, i.e., inherently stochastic and irreducible. As wisely stated in the proverb "climate is what you expect, weather is what you get", a specific region will experience one stochastic realisation of the climate system, but never exactly the expected climate change signal as given by a multi model mean. Depending on the meteorological variable, region and lead time, the signal might be strong or weak compared to the stochastic component. In cases of a low signal-to-noise ratio, even if the climate change signal is a well defined trend, no trends or even opposite trends might be experienced. Here I propose to use the time of emergence (TOE) to quantify and communicate when climate change trends will exceed the internal variability. The TOE provides a useful measure for end users to assess the time horizon for implementing adaptation measures. Furthermore, internal variability is scale dependent - the more local the scale, the stronger the influence of internal climate variability. Thus investigating the TOE as a function of spatial scale could help to assess the required spatial scale for implementing adaptation measures. I exemplify this proposal with a recently published study on the TOE for mean and heavy precipitation trends in Europe. In some regions trends emerge only late in the 21st century or even later, suggesting that in these regions adaptation to internal variability rather than to climate change is required. Yet in other regions the climate change signal is strong, urging for timely adaptation. Douglas Maraun, When at what scale will trends in European mean and heavy precipitation emerge? Env. Res. Lett., in press, 2013.

Reply to Comment by Laprise on 'the Added Value to Global Model Projections of Climate Change by Dynamical Downscaling: a Case Study over the Continental U.S. Using the GISS-ModelE2 and WRF Models'

NASA Technical Reports Server (NTRS)

Shindell, Drew Todd; Racherla, Pavan; Milly, George Peter

2014-01-01

In his comment, Laprise raises several points that we agree merit consideration. His primary critique is that our study [Racherla et al., 2012] tested the ability of the WRF regional climate model to reproduce historical temperature and precipitation change relative to the driving global climate model (GCM) using only a single simulation rather than an ensemble. He asserts that the observed changes are smaller than the internal variability in the climate system (i.e., not statistically significant) and that thus a single simulation should not necessarily be able to capture the observations. Laprise points out that the statistical signal is reduced for a multi-decadal trend such as the one we analyzed in comparison with mean climatology and cites two studies showing that for particular climate parameters it can take any years for a signal to be discerned over internal variability. He states that The results of theexperiment as designed were strongly influenced by the presence of internal variability and sampling errors,which masked the rather small climate changes that may have occurred as a consequence of changes inforcing during the period considered. While Laprise discusses statistics in general terms at some length, for the actual climate trends examined in our study, he offers no evidence that the forced signal was smallcompared with internal variability. The two studies he cites [de Ela et al., 2013; Maraun, 2013] do not provide convincing evidence as they concern climate variables averaged over different times and areas. One in fact examines extreme precipitation events, which by definition are rare and thus have a lower significance level. We accept the general point that it is important to consider internal variability, and as noted in our paper we agree that an ensemble of simulations is in principle an optimal, though computationally expensive, approach. While we did not present the statistical significance of the observations in our original paper, we have now evaluated those for the regional temperature trends used in our study to evaluate the added value of WRF and thus can analyze data as to the magnitude of the trends with respect to internal variability.

Employing 454 amplicon pyrosequencing to reveal intragenomic divergence in the internal transcribed spacer rDNA region in fungi

Treesearch

Daniel L. Lindner; Tor Carlsen; Henrik Nilsson; Marie Davey; Trond Schumacher; Havard. Kauserud

2013-01-01

The rDNA internal transcribed spacer (ITS) region has been accepted as a DNA barcoding marker for fungi and is widely used in phylogenetic studies; however, intragenomic ITS variability has been observed in a broad range of taxa, including prokaryotes, plants, animals, and fungi, and this variability has the potential to inflate species richness estimates in molecular...

Attitudinal and Motivational Variables Related to Mathematics Achievement in Jordan: Findings from the Third International Mathematics and Science Study (TIMSS)

ERIC Educational Resources Information Center

Hammouri, Hind

2004-01-01

The purpose of the present study was to examine the effects of student-related variables on achievement in mathematics. The sample consisted of 3736 13-year-old Jordanian 8th-graders who participated in the Third International Mathematics and Science Study (TIMSS). The participants completed a student questionnaire and participated in the…

How predictable are equatorial Atlantic surface winds?

NASA Astrophysics Data System (ADS)

Richter, Ingo; Doi, Takeshi; Behera, Swadhin

2017-04-01

Sensitivity tests with the SINTEX-F general circulation model (GCM) as well as experiments from the Coupled Model Intercomparison Project phase 5 (CMIP5) are used to examine the extent to which sea-surface temperature (SST) anomalies contribute to the variability and predictability of monthly mean surface winds in the equatorial Atlantic. In the SINTEX-F experiments, a control experiment with prescribed observed SST for the period 1982-2014 is modified by inserting climatological values in certain regions, thereby eliminating SST anomalies. When SSTs are set to climatology in the tropical Atlantic only (30S to 30N), surface wind variability over the equatorial Atlantic (5S-5N) decreases by about 40% in April-May-June (AMJ). This suggests that about 60% of surface wind variability is due to either internal atmospheric variability or SSTs anomalies outside the tropical Atlantic. A further experiment with climatological SSTs in the equatorial Pacific indicates that another 10% of variability in AMJ may be due to remote influences from that basin. Experiments from the CMIP5 archive, in which climatological SSTs are prescribed globally, tend to confirm the results from SINTEX-F but show a wide spread. In some models, the equatorial Atlantic surface wind variability decreases by more than 90%, while in others it even increases. Overall, the results suggest that about 50-60% of surface wind variance in AMJ is predictable, while the rest is due to internal atmospheric variability. Other months show significantly lower predictability. The relatively strong internal variability as well as the influence of remote SSTs suggest a limited role for coupled ocean-atmosphere feedbacks in equatorial Atlantic variability.

International spinal cord injury skin and thermoregulation function basic data set.

PubMed

Karlsson, A K; Krassioukov, A; Alexander, M S; Donovan, W; Biering-Sørensen, F

2012-07-01

To create an international spinal cord injury (SCI) skin and thermoregulation basic data set within the framework of the International SCI Data Sets. An international working group. The draft of the data set was developed by a working group comprising members appointed by the American Spinal Injury Association (ASIA), the International Spinal Cord Society (ISCoS) and a representative of the Executive Committee of the International SCI Standards and Data Sets. The final version of the data set was developed after review and comments by members of the Executive Committee of the International SCI Standards and Data Sets, the ISCoS Scientific Committee, ASIA Board, relevant and interested international organizations and societies, individual persons with specific interest and the ISCoS Council. To make the data set uniform, each variable and each response category within each variable have been specifically defined to promote the collection and reporting of comparable minimal data. Variables included in the present data set are: date of data collection, thermoregulation history after SCI, including hyperthermia or hypothermia (noninfectious or infectious), as well as the history of hyperhidrosis or hypohidrosis above or below level of lesion. Body temperature and the time of measurement are included. Details regarding the presence of any pressure ulcer and stage, location and size of the ulcer(s), date of appearance of the ulcer(s) and whether surgical treatment has been performed are included. The history of any pressure ulcer during the last 12 months is also noted.

International spinal cord injury cardiovascular function basic data set.

PubMed

Krassioukov, A; Alexander, M S; Karlsson, A-K; Donovan, W; Mathias, C J; Biering-Sørensen, F

2010-08-01

To create an International Spinal Cord Injury (SCI) Cardiovascular Function Basic Data Set within the framework of the International SCI Data Sets. An international working group. The draft of the data set was developed by a working group comprising members appointed by the American Spinal Injury Association (ASIA), the International Spinal Cord Society (ISCoS) and a representative of the executive committee of the International SCI Standards and Data Sets. The final version of the data set was developed after review by members of the executive committee of the International SCI Standards and Data Sets, the ISCoS scientific committee, ASIA board, relevant and interested international organizations and societies, individual persons with specific interest and the ISCoS Council. To make the data set uniform, each variable and each response category within each variable have been specifically defined in a way that is designed to promote the collection and reporting of comparable minimal data. The variables included in the International SCI Cardiovascular Function Basic Data Set include the following items: date of data collection, cardiovascular history before the spinal cord lesion, events related to cardiovascular function after the spinal cord lesion, cardiovascular function after the spinal cord lesion, medications affecting cardiovascular function on the day of examination; and objective measures of cardiovascular functions, including time of examination, position of examination, pulse and blood pressure. The complete instructions for data collection and the data sheet itself are freely available on the websites of both ISCoS (http://www.iscos.org.uk) and ASIA (http://www.asia-spinalinjury.org).

Estimating trends in the global mean temperature record

NASA Astrophysics Data System (ADS)

Poppick, Andrew; Moyer, Elisabeth J.; Stein, Michael L.

2017-06-01

Given uncertainties in physical theory and numerical climate simulations, the historical temperature record is often used as a source of empirical information about climate change. Many historical trend analyses appear to de-emphasize physical and statistical assumptions: examples include regression models that treat time rather than radiative forcing as the relevant covariate, and time series methods that account for internal variability in nonparametric rather than parametric ways. However, given a limited data record and the presence of internal variability, estimating radiatively forced temperature trends in the historical record necessarily requires some assumptions. Ostensibly empirical methods can also involve an inherent conflict in assumptions: they require data records that are short enough for naive trend models to be applicable, but long enough for long-timescale internal variability to be accounted for. In the context of global mean temperatures, empirical methods that appear to de-emphasize assumptions can therefore produce misleading inferences, because the trend over the twentieth century is complex and the scale of temporal correlation is long relative to the length of the data record. We illustrate here how a simple but physically motivated trend model can provide better-fitting and more broadly applicable trend estimates and can allow for a wider array of questions to be addressed. In particular, the model allows one to distinguish, within a single statistical framework, between uncertainties in the shorter-term vs. longer-term response to radiative forcing, with implications not only on historical trends but also on uncertainties in future projections. We also investigate the consequence on inferred uncertainties of the choice of a statistical description of internal variability. While nonparametric methods may seem to avoid making explicit assumptions, we demonstrate how even misspecified parametric statistical methods, if attuned to the important characteristics of internal variability, can result in more accurate uncertainty statements about trends.

Stability of Intercellular Exchange of Biochemical Substances Affected by Variability of Environmental Parameters

NASA Astrophysics Data System (ADS)

Mihailović, Dragutin T.; Budinčević, Mirko; Balaž, Igor; Mihailović, Anja

Communication between cells is realized by exchange of biochemical substances. Due to internal organization of living systems and variability of external parameters, the exchange is heavily influenced by perturbations of various parameters at almost all stages of the process. Since communication is one of essential processes for functioning of living systems it is of interest to investigate conditions for its stability. Using previously developed simplified model of bacterial communication in a form of coupled difference logistic equations we investigate stability of exchange of signaling molecules under variability of internal and external parameters.

International lower urinary tract function basic spinal cord injury data set.

PubMed

Biering-Sørensen, F; Craggs, M; Kennelly, M; Schick, E; Wyndaele, J-J

2008-05-01

To create the International Lower Urinary Tract Function Basic Spinal Cord Injury (SCI) Data Set within the framework of the International SCI Data Sets. International working group. The draft of the Data Set was developed by a working group consisting of the members appointed by the International Continence Society, the European Association of Urology, the American Spinal Injury Association (ASIA), the International Spinal Cord Society (ISCoS) and a representative of the Executive Committee of the International SCI Standards and Data Sets. The final version of the Data Set was developed after review and comments by the members of the Executive Committee of the International SCI Standards and Data Sets, the ISCoS Scientific Committee, ASIA Board, relevant and interested (international) organizations and societies (around 40) and persons, and the ISCoS Council. Endorsement of the Data Set by relevant organizations and societies will be obtained. To make the Data Set uniform, each variable and each response category within each variable have been specifically defined in a way that is designed to promote the collection and reporting of comparable minimal data. Variables included in the International Lower Urinary Tract Function Basic SCI Data Set are as follows: date of data collection, urinary tract impairment unrelated to spinal cord lesion, awareness of the need to empty the bladder, bladder emptying, average number of voluntary bladder emptyings per day during the last week, incontinence within the last 3 months, collecting appliances for urinary incontinence, any drugs for the urinary tract within the last year, surgical procedures on the urinary tract and any change in urinary symptoms within the last year. Complete instruction for data collection, data sheet and training cases available at the website of ISCoS (www.iscos.org.uk) and ASIA (www.asia-spinalinjury.org).

The drive for muscularity in men: media influences and objectification theory.

PubMed

Daniel, Samantha; Bridges, Sara K

2010-01-01

Presently, objectification theory has yielded mixed results when utilized to explain body image concerns in men. An online survey assessing internalization of media ideals, self-objectification, body surveillance, body shame, the drive for muscularity, and body mass index (BMI) was completed by 244 predominantly college-aged males. Path analyses were used to investigate relationships among these variables where it was hypothesized that objectification variables would mediate the relationship between internalization of media ideals and the drive for muscularity. Internalization of media ideals was the strongest predictor of the drive for muscularity, followed by BMI, though variables of objectification theory had no impact on the drive for muscularity contrary to hypotheses. The results suggest that objectification theory may not be applicable to men as it is currently measured. Copyright 2009 Elsevier Ltd. All rights reserved.

Dynamic characteristics of a two-stage variable-mass flexible missile with internal flow

NASA Technical Reports Server (NTRS)

Meirovitch, L.; Bankovskis, J.

1972-01-01

A general formulation of the dynamical problems associated with powered flight of a two stage flexible, variable-mass missile with internal flow, discrete masses, and aerodynamic forces is presented. The formulation comprises six ordinary differential equations for the rigid body motion, 3n ordinary differential equations for the n discrete masses and three partial differential equations with the appropriate boundary conditions for the elastic motion. This set of equations is modified to represent a single stage flexible, variable-mass missile with internal flow and aerodynamic forces. The rigid-body motion consists then of three translations and three rotations, whereas the elastic motion is defined by one longitudinal and two flexural displacements, the latter about two orthogonal transverse axes. The differential equations are nonlinear and, in addition, they possess time-dependent coefficients due to the mass variation.

Influence of Internal and External Noise on Spontaneous Visuomotor Synchronization.

PubMed

Varlet, Manuel; Schmidt, R C; Richardson, Michael J

2016-01-01

Historically, movement noise or variability is considered to be an undesirable property of biological motor systems. In particular, noise is typically assumed to degrade the emergence and stability of rhythmic motor synchronization. Recently, however, it has been suggested that small levels of noise might actually improve the functioning of motor systems and facilitate their adaptation to environmental events. Here, the authors investigated whether noise can facilitate spontaneous rhythmic visuomotor synchronization. They examined the influence of internal noise in the rhythmic limb movements of participants and external noise in the movement of an oscillating visual stimulus on the occurrence of spontaneous synchronization. By indexing the natural frequency variability of participants and manipulating the frequency variability of the visual stimulus, the authors demonstrated that both internal and external noise degrade synchronization when the participants' and stimulus movement frequencies are similar, but can actually facilitate synchronization when the frequencies are different. Furthermore, the two kinds of noise interact with each other. Internal noise facilitates synchronization only when external noise is minimal and vice versa. Too much internal and external noise together degrades synchronization. These findings open new perspectives for better understanding the role of noise in human rhythmic coordination.

Compact Hybrid Automotive Propulsion System

NASA Technical Reports Server (NTRS)

Lupo, G.

1986-01-01

Power train proposed for experimental vehicle powered by internal combustion engine and electric motor. Intended for front-wheel drive automobile, power train mass produced using existing technology. System includes internal-combustion engine, electric motor, continuously variable transmission, torque converter, differential, and control and adjustment systems for electric motor and transmission. Continuously variable transmission integrated into hydraulic system that also handles power steering and power brakes. Batteries for electric motor mounted elsewhere in vehicle.

A Multi-Model Assessment for the 2006 and 2010 Simulations under the Air Quality Model Evaluation International Initiative (AQMEII) Phase 2 over North America: Part II. Evaluation of Column Variable Predictions Using Satellite Data

EPA Science Inventory

Within the context of the Air Quality Model Evaluation International Initiative phase 2 (AQMEII2) project, this part II paper performs a multi-model assessment of major column abundances of gases, radiation, aerosol, and cloud variables for 2006 and 2010 simulations with three on...

Nonlinear waves in solids with slow dynamics: an internal-variable model

PubMed Central

Berjamin, H.; Favrie, N.; Chiavassa, G.

2017-01-01

In heterogeneous solids such as rocks and concrete, the speed of sound diminishes with the strain amplitude of a dynamic loading (softening). This decrease, known as ‘slow dynamics’, occurs at time scales larger than the period of the forcing. Also, hysteresis is observed in the steady-state response. The phenomenological model by Vakhnenko et al. (2004 Phys. Rev. E 70, 015602. (doi:10.1103/PhysRevE.70.015602)) is based on a variable that describes the softening of the material. However, this model is one dimensional and it is not thermodynamically admissible. In the present article, a three-dimensional model is derived in the framework of the finite-strain theory. An internal variable that describes the softening of the material is introduced, as well as an expression of the specific internal energy. A mechanical constitutive law is deduced from the Clausius–Duhem inequality. Moreover, a family of evolution equations for the internal variable is proposed. Here, an evolution equation with one relaxation time is chosen. By construction, this new model of the continuum is thermodynamically admissible and dissipative (inelastic). In the case of small uniaxial deformations, it is shown analytically that the model reproduces qualitatively the main features of real experiments. PMID:28588408

Internally Generated and Externally Forced Multidecadal Oceanic Modes and their Influence on the Summer Rainfall over East Asia

NASA Astrophysics Data System (ADS)

Si, D.; Hu, A.

2017-12-01

The interdecadal oceanic variabilities can be generated from both internal and external processes, and these variabilities can significantly modulate our climate on global and regional scale, such as the warming slowdown in the early 21st century, and the rainfall in East Asia. By analyzing simulations from a unique Community Earth System Model (CESM) Large Ensemble (CESM_LE) project, we show that the Interdecadal Pacific Oscillation (IPO) is primarily an internally generated oceanic variability, while the Atlantic Multidecadal Oscillation (AMO) may be an oceanic variability generated by internal oceanic processes and modulated by external forcings in the 20th century. Although the observed relationship between IPO and the Yangtze-Huaihe River valley (YHRV) summer rainfall in China is well simulated in both the preindustrial control and 20th century ensemble, none of the 20th century ensemble members can reproduce the observed time evolution of both IPO and YHRV due to the unpredictable nature of IPO on multidecade timescale. On the other hand, although CESM_LE cannot reproduce the observed relationship between AMO and Huanghe River valley (HRV) summer rainfall of China in the preindustrial control simulation, this relationship in the 20th century simulations is well reproduced, and the chance to reproduce the observed time evolution of both AMO and HRV rainfall is about 30%, indicating the important role of the interaction between the internal processes and the external forcing to realistically simulate the AMO and HRV rainfall.

TIMSS 2011 User Guide for the International Database. Supplement 2: National Adaptations of International Background Questionnaires

ERIC Educational Resources Information Center

Foy, Pierre, Ed.; Arora, Alka, Ed.; Stanco, Gabrielle M., Ed.

2013-01-01

This supplement describes national adaptations made to the international version of the TIMSS 2011 background questionnaires. This information provides users with a guide to evaluate the availability of internationally comparable data for use in secondary analyses involving the TIMSS 2011 background variables. Background questionnaire adaptations…

Forced Atlantic Multidecadal Variability Over the Past Millennium

NASA Astrophysics Data System (ADS)

Halloran, P. R.; Reynolds, D.; Scourse, J. D.; Hall, I. R.

2016-02-01

Paul R. Halloran, David J. Reynolds, Ian R. Hall and James D. Scourse Multidecadal variability in Atlantic sea surface temperatures (SSTs) plays a first order role in determining regional atmospheric circulation and moisture transport, with major climatic consequences. These regional climate impacts range from drought in the Sahel and South America, though increased hurricane activity and temperature extremes, to modified monsoonal rainfall. Multidecadal Atlantic SST variability could arise through internal variability in the Atlantic Meridional Overturning Circulation (AMOC) (e.g., Knight et al., 2006), or through externally forced change (e.g. Booth et al., 2012). It is critical that we know whether internal or external forcing dominates if we are to provide useful near-term climate projections in the Atlantic region. A persuasive argument that internal variability plays an important role in Atlantic Multidecadal Variability is that periodic SST variability has been observed throughout much of the last millennium (Mann et al., 2009), and the hypothesized external forcing of historical Atlantic Multidecadal Variability (Booth et al., 2012) is largely anthropogenic in origin. Here we combine the first annually-resolved millennial marine reconstruction with multi-model analysis, to show that the Atlantic SST variability of the last millennium can be explained by a combination of direct volcanic forcing, and indirect, forced, AMOC variability. Our results indicate that whilst climate models capture the timing of both the directly forced SST and forced AMOC-mediated SST variability, the models fail to capture the magnitude of the forced AMOC change. Does this mean that models underestimate the 21st century reduction in AMOC strength? J. Knight, C. Folland and A. Scaife., Climate impacts of the Atlantic Multidecadal Oscillation, GRL, 2006 B.B.B Booth, N. Dunstone, P.R. Halloran et al., Aerosols implicated as a prime driver of twentieth-century North Atlantic climate variability, Nature, 2012 M.E. Mann, Z. Zhang, S. Rutherford et al., Global Signatures and Dynamical Origins of the Little Ice Age and Medieval Climate Anomaly, Science, 2009

Internal fetal monitoring (image)

MedlinePlus

Internal fetal monitoring involves placing a electrode directly on the fetal scalp through the cervix. This test is performed to evaluate fetal heart rate and variability between beats, especially ...

Does internal climate variability overwhelm climate change signals in streamflow? The upper Po and Rhone basin case studies.

PubMed

Fatichi, S; Rimkus, S; Burlando, P; Bordoy, R

2014-09-15

Projections of climate change effects in streamflow are increasingly required to plan water management strategies. These projections are however largely uncertain due to the spread among climate model realizations, internal climate variability, and difficulties in transferring climate model results at the spatial and temporal scales required by catchment hydrology. A combination of a stochastic downscaling methodology and distributed hydrological modeling was used in the ACQWA project to provide projections of future streamflow (up to year 2050) for the upper Po and Rhone basins, respectively located in northern Italy and south-western Switzerland. Results suggest that internal (stochastic) climate variability is a fundamental source of uncertainty, typically comparable or larger than the projected climate change signal. Therefore, climate change effects in streamflow mean, frequency, and seasonality can be masked by natural climatic fluctuations in large parts of the analyzed regions. An exception to the overwhelming role of stochastic variability is represented by high elevation catchments fed by glaciers where streamflow is expected to be considerably reduced due to glacier retreat, with consequences appreciable in the main downstream rivers in August and September. Simulations also identify regions (west upper Rhone and Toce, Ticino river basins) where a strong precipitation increase in the February to April period projects streamflow beyond the range of natural climate variability during the melting season. This study emphasizes the importance of including internal climate variability in climate change analyses, especially when compared to the limited uncertainty that would be accounted for by few deterministic projections. The presented results could be useful in guiding more specific impact studies, although design or management decisions should be better based on reliability and vulnerability criteria as suggested by recent literature. Copyright © 2013 Elsevier B.V. All rights reserved.

Variability of North Atlantic Hurricane Frequency in a Large Ensemble of High-Resolution Climate Simulations

NASA Astrophysics Data System (ADS)

Mei, W.; Kamae, Y.; Xie, S. P.

2017-12-01

Forced and internal variability of North Atlantic hurricane frequency during 1951-2010 is studied using a large ensemble of climate simulations by a 60-km atmospheric general circulation model that is forced by observed sea surface temperatures (SSTs). The simulations well capture the interannual-to-decadal variability of hurricane frequency in best track data, and further suggest a possible underestimate of hurricane counts in the current best track data prior to 1966 when satellite measurements were unavailable. A genesis potential index (GPI) averaged over the Main Development Region (MDR) accounts for more than 80% of the forced variations in hurricane frequency, with potential intensity and vertical wind shear being the dominant factors. In line with previous studies, the difference between MDR SST and tropical mean SST is a simple but useful predictor; a one-degree increase in this SST difference produces 7.1±1.4 more hurricanes. The hurricane frequency also exhibits internal variability that is comparable in magnitude to the interannual variability. The 100-member ensemble allows us to address the following important questions: (1) Are the observations equivalent to one realization of such a large ensemble? (2) How many ensemble members are needed to reproduce the variability in observations and in the forced component of the simulations? The sources of the internal variability in hurricane frequency will be identified and discussed. The results provide an explanation for the relatively week correlation ( 0.6) between MDR GPI and hurricane frequency on interannual timescales in observations.

ENSO-related Interannual Variability of Southern Hemisphere Atmospheric Circulation: Assessment and Projected Changes in CMIP5 Models

NASA Astrophysics Data System (ADS)

Frederiksen, Carsten; Grainger, Simon; Zheng, Xiaogu; Sisson, Janice

2013-04-01

ENSO variability is an important driver of the Southern Hemisphere (SH) atmospheric circulation. Understanding the observed and projected changes in ENSO variability is therefore important to understanding changes in Australian surface climate. Using a recently developed methodology (Zheng et al., 2009), the coherent patterns, or modes, of ENSO-related variability in the SH atmospheric circulation can be separated from modes that are related to intraseasonal variability or to changes in radiative forcings. Under this methodology, the seasonal mean SH 500 hPa geopotential height is considered to consist of three components. These are: (1) an intraseasonal component related to internal dynamics on intraseasonal time scales; (2) a slow-internal component related to internal dynamics on slowly varying (interannual or longer) time scales, including ENSO; and (3) a slow-external component related to external (i.e. radiative) forcings. Empirical Orthogonal Functions (EOFs) are used to represent the modes of variability of the interannual covariance of the three components. An assessment is first made of the modes in models from the Coupled Model Intercomparison Project Phase 5 (CMIP5) dataset for the SH summer and winter seasons in the 20th century. In reanalysis data, two EOFs of the slow component (which includes the slow-internal and slow-external components) have been found to be related to ENSO variability (Frederiksen and Zheng, 2007). In SH summer, the CMIP5 models reproduce the leading ENSO mode very well when the structures of the EOF and the associated SST, and associated variance are considered. There is substantial improvement in this mode when compared with the CMIP3 models shown in Grainger et al. (2012). However, the second ENSO mode in SH summer has a poorly reproduced EOF structure in the CMIP5 models, and the associated variance is generally underestimated. In SH winter, the performance of the CMIP5 models in reproducing the structure and variance is similar for both ENSO modes, with the associated variance being generally underestimated. Projected changes in the modes in the 21st century are then investigated using ensembles of CMIP5 models that reproduce well the 20th century slow modes. The slow-internal and slow-external components are examined separately, allowing the projected changes in the response to ENSO variability to be separated from the response to changes in greenhouse gas concentrations. By using several ensembles, the model-dependency of the projected changes in the ENSO-related slow-internal modes is examined. Frederiksen, C. S., and X. Zheng, 2007: Variability of seasonal-mean fields arising from intraseasonal variability. Part 3: Application to SH winter and summer circulations. Climate Dyn., 28, 849-866. Grainger, S., C. S. Frederiksen, and X. Zheng, 2012: Modes of interannual variability of Southern Hemisphere atmospheric circulation in CMIP3 models: Assessment and Projections. Climate Dyn., in press. Zheng, X., D. M. Straus, C. S. Frederiksen, and S. Grainger, 2009: Potentially predictable patterns of extratropical tropospheric circulation in an ensemble of climate simulations with the COLA AGCM. Quart. J. Roy. Meteor. Soc., 135, 1816-1829.

Uncertainty in Indian Ocean Dipole response to global warming: the role of internal variability

NASA Astrophysics Data System (ADS)

Hui, Chang; Zheng, Xiao-Tong

2018-01-01

The Indian Ocean Dipole (IOD) is one of the leading modes of interannual sea surface temperature (SST) variability in the tropical Indian Ocean (TIO). The response of IOD to global warming is quite uncertain in climate model projections. In this study, the uncertainty in IOD change under global warming, especially that resulting from internal variability, is investigated based on the community earth system model large ensemble (CESM-LE). For the IOD amplitude change, the inter-member uncertainty in CESM-LE is about 50% of the intermodel uncertainty in the phase 5 of the coupled model intercomparison project (CMIP5) multimodel ensemble, indicating the important role of internal variability in IOD future projection. In CESM-LE, both the ensemble mean and spread in mean SST warming show a zonal positive IOD-like (pIOD-like) pattern in the TIO. This pIOD-like mean warming regulates ocean-atmospheric feedbacks of the interannual IOD mode, and weakens the skewness of the interannual variability. However, as the changes in oceanic and atmospheric feedbacks counteract each other, the inter-member variability in IOD amplitude change is not correlated with that of the mean state change. Instead, the ensemble spread in IOD amplitude change is correlated with that in ENSO amplitude change in CESM-LE, reflecting the close inter-basin relationship between the tropical Pacific and Indian Ocean in this model.

Climate change and water table fluctuation: Implications for raised bog surface variability

NASA Astrophysics Data System (ADS)

Taminskas, Julius; Linkevičienė, Rita; Šimanauskienė, Rasa; Jukna, Laurynas; Kibirkštis, Gintautas; Tamkevičiūtė, Marija

2018-03-01

Cyclic peatland surface variability is influenced by hydrological conditions that highly depend on climate and/or anthropogenic activities. A low water level leads to a decrease of peatland surface and an increase of C emissions into the atmosphere, whereas a high water level leads to an increase of peatland surface and carbon sequestration in peatlands. The main aim of this article is to evaluate the influence of hydrometeorological conditions toward the peatland surface and its feedback toward the water regime. A regional survey of the raised bog water table fluctuation and surface variability was made in one of the largest peatlands in Lithuania. Two appropriate indicators for different peatland surface variability periods (increase and decrease) were detected. The first one is an 200 mm y- 1 average net rainfall over a three-year range. The second one is an average annual water depth of 25-30 cm. The application of these indicators enabled the reconstruction of Čepkeliai peatland surface variability during a 100 year period. Processes of peatland surface variability differ in time and in separate parts of peatland. Therefore, internal subbasins in peatland are formed. Subbasins involve autogenic processes that can later affect their internal hydrology, nutrient status, and vegetation succession. Internal hydrological conditions, surface fluctuation, and vegetation succession in peatland subbasins should be taken into account during evaluation of their state, nature management projects, and other peatland research works.

Lagrange thermodynamic potential and intrinsic variables for He-3 He-4 dilute solutions

NASA Technical Reports Server (NTRS)

Jackson, H. W.

1983-01-01

For a two-fluid model of dilute solutions of He-3 in liquid He-4, a thermodynamic potential is constructed that provides a Lagrangian for deriving equations of motion by a variational procedure. This Lagrangian is defined for uniform velocity fields as a (negative) Legendre transform of total internal energy, and its primary independent variables, together with their thermodynamic conjugates, are identified. Here, similarities between relations in classical physics and quantum statistical mechanics serve as a guide for developing an alternate expression for this function that reveals its character as the difference between apparent kinetic energy and intrinsic internal energy. When the He-3 concentration in the mixtures tends to zero, this expression reduces to Zilsel's formula for the Lagrangian for pure liquid He-4. An investigation of properties of the intrinsic internal energy leads to the introduction of intrinsic chemical potentials along with other intrinsic variables for the mixtures. Explicit formulas for these variables are derived for a noninteracting elementary excitation model of the fluid. Using these formulas and others also derived from quantum statistical mechanics, another equivalent expression for the Lagrangian is generated.

Long-term Internal Variability of the Tropical Pacific Atmosphere-Ocean System

NASA Astrophysics Data System (ADS)

Hadi Bordbar, Mohammad; Martin, Thomas; Park, Wonsun; Latif, Mojib

2016-04-01

The tropical Pacific has featured some remarkable trends during the recent decades such as an unprecedented strengthening of the Trade Winds, a strong cooling of sea surface temperatures (SST) in the eastern and central part, thereby slowing global warming and strengthening the zonal SST gradient, and highly asymmetric sea level trends with an accelerated rise relative to the global average in the western and a drop in the eastern part. These trends have been linked to an anomalously strong Pacific Walker Circulation, the major zonal atmospheric overturning cell in the tropical Pacific sector, but the origin of the strengthening is controversial. Here we address the question as to whether the recent decadal trends in the tropical Pacific atmosphere-ocean system are within the range of internal variability, as simulated in long unforced integrations of global climate models. We show that the recent trends are still within the range of long-term internal decadal variability. Further, such variability strengthens in response to enhanced greenhouse gas concentrations, which may further hinder detection of anthropogenic climate signals in that region.

Accelerated warming of the Southern Ocean and its impacts on the hydrological cycle and sea ice.

PubMed

Liu, Jiping; Curry, Judith A

2010-08-24

The observed sea surface temperature in the Southern Ocean shows a substantial warming trend for the second half of the 20th century. Associated with the warming, there has been an enhanced atmospheric hydrological cycle in the Southern Ocean that results in an increase of the Antarctic sea ice for the past three decades through the reduced upward ocean heat transport and increased snowfall. The simulated sea surface temperature variability from two global coupled climate models for the second half of the 20th century is dominated by natural internal variability associated with the Antarctic Oscillation, suggesting that the models' internal variability is too strong, leading to a response to anthropogenic forcing that is too weak. With increased loading of greenhouse gases in the atmosphere through the 21st century, the models show an accelerated warming in the Southern Ocean, and indicate that anthropogenic forcing exceeds natural internal variability. The increased heating from below (ocean) and above (atmosphere) and increased liquid precipitation associated with the enhanced hydrological cycle results in a projected decline of the Antarctic sea ice.

[Anthropometric study and evaluation of the nutritional status of a population school children in Granada; comparison of national and international reference standards].

PubMed

González Jiménez, E; Aguilar Cordero, M J; Álvarez Ferre, J; Padilla López, C; Valenza, M C

2012-01-01

Recent studies show an alarming increase in levels of overweight and obesity among children and adolescents. The main objectives of this research were the following: (i) to carry out an anthropometric evaluation of the nutritional status and body composition of school children in the city and province of Granada; (ii) to compare the nutritional status of this population sample with national and international reference standards. The results obtained in this study showed that the general prevalence of overweight in both sexes was 22.03% and that 9.12% of the children were obese. Statistically significant differences were found between the variable, weight for age and sex (p < 0.05) and the variable, height for age and sex (p < 0.05). Regarding the body mass index, no statistically significant differences were found for the variable, sex (p = 0.182). This contrasted with the variable, age, which did show statistically significant differences (p < 0.05). As a conclusion, the results of our study highlighted the fact that these anthropometric values were much higher than national and international reference standards.

Disentangling Global Warming, Multidecadal Variability, and El Niño in Pacific Temperatures

NASA Astrophysics Data System (ADS)

Wills, Robert C.; Schneider, Tapio; Wallace, John M.; Battisti, David S.; Hartmann, Dennis L.

2018-03-01

A key challenge in climate science is to separate observed temperature changes into components due to internal variability and responses to external forcing. Extended integrations of forced and unforced climate models are often used for this purpose. Here we demonstrate a novel method to separate modes of internal variability from global warming based on differences in time scale and spatial pattern, without relying on climate models. We identify uncorrelated components of Pacific sea surface temperature variability due to global warming, the Pacific Decadal Oscillation (PDO), and the El Niño-Southern Oscillation (ENSO). Our results give statistical representations of PDO and ENSO that are consistent with their being separate processes, operating on different time scales, but are otherwise consistent with canonical definitions. We isolate the multidecadal variability of the PDO and find that it is confined to midlatitudes; tropical sea surface temperatures and their teleconnections mix in higher-frequency variability. This implies that midlatitude PDO anomalies are more persistent than previously thought.

An Assessment of Team Development at the Air Force Flight Dynamics Laboratory.

DTIC Science & Technology

1980-09-01

FLIGHT DYNAMICS LABORATORY S. PERFORMING OG. REPORT NUMGER 7. AUTHOR(*) S. CONTRACT ON GRANT NUMBER(s) illiam D. Rutley, Captain, USAF _. PERFORMING ...the change from 1978 to 1980 on eleven criterion variables, employee job satisfaction, job motivation and absenteeism ; five organizational climate...variables except absenteeism . Absenteeism data were obtained from AFFDL intern~al records. The four main pro- duct divisions of AFlDL se.-ve-i as subjects

An internal variable constitutive model for the large deformation of metals at high temperatures

NASA Technical Reports Server (NTRS)

Brown, Stuart; Anand, Lallit

1988-01-01

The advent of large deformation finite element methodologies is beginning to permit the numerical simulation of hot working processes whose design until recently has been based on prior industrial experience. Proper application of such finite element techniques requires realistic constitutive equations which more accurately model material behavior during hot working. A simple constitutive model for hot working is the single scalar internal variable model for isotropic thermal elastoplasticity proposed by Anand. The model is recalled and the specific scalar functions, for the equivalent plastic strain rate and the evolution equation for the internal variable, presented are slight modifications of those proposed by Anand. The modified functions are better able to represent high temperature material behavior. The monotonic constant true strain rate and strain rate jump compression experiments on a 2 percent silicon iron is briefly described. The model is implemented in the general purpose finite element program ABAQUS.

Variable-Internal-Stores models of microbial growth and metabolism with dynamic allocation of cellular resources.

PubMed

Nev, Olga A; van den Berg, Hugo A

2017-01-01

Variable-Internal-Stores models of microbial metabolism and growth have proven to be invaluable in accounting for changes in cellular composition as microbial cells adapt to varying conditions of nutrient availability. Here, such a model is extended with explicit allocation of molecular building blocks among various types of catalytic machinery. Such an extension allows a reconstruction of the regulatory rules employed by the cell as it adapts its physiology to changing environmental conditions. Moreover, the extension proposed here creates a link between classic models of microbial growth and analyses based on detailed transcriptomics and proteomics data sets. We ascertain the compatibility between the extended Variable-Internal-Stores model and the classic models, demonstrate its behaviour by means of simulations, and provide a detailed treatment of the uniqueness and the stability of its equilibrium point as a function of the availabilities of the various nutrients.

A Viscoelastic Hybrid Shell Finite Element

NASA Technical Reports Server (NTRS)

Johnson, Arthur

1999-01-01

An elastic large displacement thick-shell hybrid finite element is modified to allow for the calculation of viscoelastic stresses. Internal strain variables are introduced at he element's stress nodes and are employed to construct a viscous material model. First order ordinary differential equations relate the internal strain variables to the corresponding elastic strains at the stress nodes. The viscous stresses are computed from the internal strain variables using viscous moduli which are a fraction of the elastic moduli. The energy dissipated by the action of the viscous stresses in included in the mixed variational functional. Nonlinear quasi-static viscous equilibrium equations are then obtained. Previously developed Taylor expansions of the equilibrium equations are modified to include the viscous terms. A predictor-corrector time marching solution algorithm is employed to solve the algebraic-differential equations. The viscous shell element is employed to numerically simulate a stair-step loading and unloading of an aircraft tire in contact with a frictionless surface.

Internalized stigma among psychiatric outpatients: Associations with quality of life, functioning, hope and self-esteem.

PubMed

Picco, Louisa; Pang, Shirlene; Lau, Ying Wen; Jeyagurunathan, Anitha; Satghare, Pratika; Abdin, Edimansyah; Vaingankar, Janhavi Ajit; Lim, Susan; Poh, Chee Lien; Chong, Siow Ann; Subramaniam, Mythily

2016-12-30

This study aimed to: (i) determine the prevalence, socio-demographic and clinical correlates of internalized stigma and (ii) explore the association between internalized stigma and quality of life, general functioning, hope and self-esteem, among a multi-ethnic Asian population of patients with mental disorders. This cross-sectional, survey recruited adult patients (n=280) who were seeking treatment at outpatient and affiliated clinics of the only tertiary psychiatric hospital in Singapore. Internalized stigma was measured using the Internalized Stigma of Mental Illness scale. 43.6% experienced moderate to high internalized stigma. After making adjustments in multiple logistic regression analysis, results revealed there were no significant socio-demographic or clinical correlates relating to internalized stigma. Individual logistic regression models found a negative relationship between quality of life, self-esteem, general functioning and internalized stigma whereby lower scores were associated with higher internalized stigma. In the final regression model, which included all psychosocial variables together, self-esteem was the only variable significantly and negatively associated with internalized stigma. The results of this study contribute to our understanding of the role internalized stigma plays in patients with mental illness, and the impact it can have on psychosocial aspects of their lives. Copyright © 2016 The Authors. Published by Elsevier Ireland Ltd.. All rights reserved.

Spatial and temporal variations in mango colour, acidity, and sweetness in relation to temperature and ethylene gradients within the fruit.

PubMed

Nordey, Thibault; Léchaudel, Mathieu; Génard, Michel; Joas, Jacques

2014-11-01

Managing fruit quality is complex because many different attributes have to be taken into account, which are themselves subjected to spatial and temporal variations. Heterogeneous fruit quality has been assumed to be partly related to temperature and maturity gradients within the fruit. To test this assumption, we measured the spatial variability of certain mango fruit quality traits: colour of the peel and of the flesh, and sourness and sweetness, at different stages of fruit maturity using destructive methods as well as vis-NIR reflectance. The spatial variability of mango quality traits was compared to internal variations in thermal time, simulated by a physical model, and to internal variations in maturity, using ethylene content as an indicator. All the fruit quality indicators analysed showed significant spatial and temporal variations, regardless of the measurement method used. The heterogeneity of internal fruit quality traits was not correlated with the marked internal temperature gradient we modelled. However, variations in ethylene content revealed a strong internal maturity gradient which was correlated with the spatial variations in measured mango quality traits. Nonetheless, alone, the internal maturity gradient did not explain the variability of fruit quality traits, suggesting that other factors, such as gas, abscisic acid and water gradients, are also involved. Copyright © 2014 Elsevier GmbH. All rights reserved.

Conversion Intentions of Interns: What Are the Motivating Factors?

ERIC Educational Resources Information Center

Hurst, Jessica L.; Good, Linda K.; Gardner, Phil

2012-01-01

Purpose: The purpose of this study is to investigate interns' supervisory support expectations, psychological contract obligations, job satisfaction, perception of advancement opportunities and affective organisational commitment in an attempt to gain a better understanding of how these variables influence interns' conversion intentions.…

Processes of Internal and International Migration from Chitwan, Nepal.

PubMed

Bohra, Pratikshya; Massey, Douglas S

2009-01-01

In this study we examine which factors predict internal and international migration from Chitwan, a flat valley located in the South-Central region of Nepal, seeking to measure the effect of theoretically specified variables such as human capital, social capital, physical capital, and neighborhood socioeconomic conditions while controlling for demographic variables. We use data from the Chitwan Valley Family Study (CVFS) to estimate a series of discrete time event history models of first and repeat migration to three competing destinations: other locations within Chitwan, other districts within Nepal, and places outside of Nepal. Results support hypotheses derived from neoclassical economics, the theory of new economics of migration, social capital theory, and cumulative causation theory. Our results underscore the need for a synthetic theoretical model that incorporates factors operating at the individual, household, and community levels. The use of multiple explanatory models yields a clearer picture of the forces driving internal and international migration from rural districts in developing nations such as Nepal.

Processes of Internal and International Migration from Chitwan, Nepal

PubMed Central

Bohra, Pratikshya; Massey, Douglas S.

2011-01-01

In this study we examine which factors predict internal and international migration from Chitwan, a flat valley located in the South-Central region of Nepal, seeking to measure the effect of theoretically specified variables such as human capital, social capital, physical capital, and neighborhood socioeconomic conditions while controlling for demographic variables. We use data from the Chitwan Valley Family Study (CVFS) to estimate a series of discrete time event history models of first and repeat migration to three competing destinations: other locations within Chitwan, other districts within Nepal, and places outside of Nepal. Results support hypotheses derived from neoclassical economics, the theory of new economics of migration, social capital theory, and cumulative causation theory. Our results underscore the need for a synthetic theoretical model that incorporates factors operating at the individual, household, and community levels. The use of multiple explanatory models yields a clearer picture of the forces driving internal and international migration from rural districts in developing nations such as Nepal. PMID:21423821

Threats to the Internal Validity of Experimental and Quasi-Experimental Research in Healthcare.

PubMed

Flannelly, Kevin J; Flannelly, Laura T; Jankowski, Katherine R B

2018-01-01

The article defines, describes, and discusses the seven threats to the internal validity of experiments discussed by Donald T. Campbell in his classic 1957 article: history, maturation, testing, instrument decay, statistical regression, selection, and mortality. These concepts are said to be threats to the internal validity of experiments because they pose alternate explanations for the apparent causal relationship between the independent variable and dependent variable of an experiment if they are not adequately controlled. A series of simple diagrams illustrate three pre-experimental designs and three true experimental designs discussed by Campbell in 1957 and several quasi-experimental designs described in his book written with Julian C. Stanley in 1966. The current article explains why each design controls for or fails to control for these seven threats to internal validity.

Computational Implementation of a Thermodynamically Based Work Potential Model For Progressive Microdamage and Transverse Cracking in Fiber-Reinforced Laminates

NASA Technical Reports Server (NTRS)

Pineda, Evan J.; Waas, Anthony M.; Bednarcyk, Brett A.; Collier, Craig S.

2012-01-01

A continuum-level, dual internal state variable, thermodynamically based, work potential model, Schapery Theory, is used capture the effects of two matrix damage mechanisms in a fiber-reinforced laminated composite: microdamage and transverse cracking. Matrix microdamage accrues primarily in the form of shear microcracks between the fibers of the composite. Whereas, larger transverse matrix cracks typically span the thickness of a lamina and run parallel to the fibers. Schapery Theory uses the energy potential required to advance structural changes, associated with the damage mechanisms, to govern damage growth through a set of internal state variables. These state variables are used to quantify the stiffness degradation resulting from damage growth. The transverse and shear stiffness of the lamina are related to the internal state variables through a set of measurable damage functions. Additionally, the damage variables for a given strain state can be calculated from a set of evolution equations. These evolution equations and damage functions are implemented into the finite element method and used to govern the constitutive response of the material points in the model. Additionally, an axial failure criterion is included in the model. The response of a center-notched, buffer strip-stiffened panel subjected to uniaxial tension is investigated and results are compared to experiment.

International Spinal Cord Injury Core Data Set (version 2.0)-including standardization of reporting.

PubMed

Biering-Sørensen, F; DeVivo, M J; Charlifue, S; Chen, Y; New, P W; Noonan, V; Post, M W M; Vogel, L

2017-08-01

The study design includes expert opinion, feedback, revisions and final consensus. The objective of the study was to present the new knowledge obtained since the International Spinal Cord Injury (SCI) Core Data Set (Version 1.0) published in 2006, and describe the adjustments made in Version 2.0, including standardization of data reporting. International. Comments received from the SCI community were discussed in a working group (WG); suggestions from the WG were reviewed and revisions were made. All suggested revisions were considered, and a final version was circulated for final approval. The International SCI Core Data Set (Version 2.0) consists of 25 variables. Changes made to this version include the deletion of one variable 'Total Days Hospitalized' and addition of two variables 'Date of Rehabilitation Admission' and 'Date of Death.' The variable 'Injury Etiology' was extended with six non-traumatic categories, and corresponding 'Date of Injury' for non-traumatic cases, was defined as the date of first physician visit for symptoms related to spinal cord dysfunction. A category reflecting transgender was added. A response category was added to the variable on utilization of ventilatory assistance to document the use of continuous positive airway pressure for sleep apnea. Other clarifications were made to the text. The reporting of the pediatric SCI population was updated as age groups 0-5, 6-12, 13-14, 15-17 and 18-21. Collection of the core data set should be a basic requirement of all studies of SCI to facilitate accurate descriptions of patient populations and comparison of results across published studies from around the world.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elliott, Elizabeth J.; Yu, Sungduk; Kooperman, Gabriel J.

The sensitivities of simulated mesoscale convective systems (MCSs) in the central U.S. to microphysics and grid configuration are evaluated here in a global climate model (GCM) that also permits global-scale feedbacks and variability. Since conventional GCMs do not simulate MCSs, studying their sensitivities in a global framework useful for climate change simulations has not previously been possible. To date, MCS sensitivity experiments have relied on controlled cloud resolving model (CRM) studies with limited domains, which avoid internal variability and neglect feedbacks between local convection and larger-scale dynamics. However, recent work with superparameterized (SP) GCMs has shown that eastward propagating MCS-likemore » events are captured when embedded CRMs replace convective parameterizations. This study uses a SP version of the Community Atmosphere Model version 5 (SP-CAM5) to evaluate MCS sensitivities, applying an objective empirical orthogonal function algorithm to identify MCS-like events, and harmonizing composite storms to account for seasonal and spatial heterogeneity. A five-summer control simulation is used to assess the magnitude of internal and interannual variability relative to 10 sensitivity experiments with varied CRM parameters, including ice fall speed, one-moment and two-moment microphysics, and grid spacing. MCS sensitivities were found to be subtle with respect to internal variability, and indicate that ensembles of over 100 storms may be necessary to detect robust differences in SP-GCMs. Furthermore, these results emphasize that the properties of MCSs can vary widely across individual events, and improving their representation in global simulations with significant internal variability may require comparison to long (multidecadal) time series of observed events rather than single season field campaigns.« less

Relations between Internalizing and Externalizing Problems in Early Childhood

ERIC Educational Resources Information Center

Stone, Lisanne L.; Otten, Roy; Engels, Rutger C. M. E.; Kuijpers, Rowella C. W. M.; Janssens, Jan M. A. M.

2015-01-01

Background: Childhood internalizing and externalizing problems are closely related and often co-occur. Directional models have been employed to test how these problems are related, while few studies have tested a third variables model. Objective: This study investigates whether internalizing and externalizing problems are reciprocally or…

Identification of International Classification of Functioning, Disability and Health categories for patients with peripheral arterial disease.

PubMed

Vyskocil, Erich; Gruther, Wolfgang; Steiner, Irene; Schuhfried, Othmar

2014-07-01

Disease-specific categories of the International Classification of Functioning, Disability and Health have not yet been described for patients with chronic peripheral arterial obstructive disease (PAD). The authors examined the relationship between the categories of the Brief Core Sets for ischemic heart diseases with the Peripheral Artery Questionnaire and the ankle-brachial index to determine which International Classification of Functioning, Disability and Health categories are most relevant for patients with PAD. This is a retrospective cohort study including 77 patients with verified PAD. Statistical analyses of the relationship between International Classification of Functioning, Disability and Health categories as independent variables and the endpoints Peripheral Artery Questionnaire or ankle-brachial index were carried out by simple and stepwise linear regression models adjusting for age, sex, and leg (left vs. right). The stepwise linear regression model with the ankle-brachial index as dependent variable revealed a significant effect of the variables blood vessel functions and muscle endurance functions. Calculating a stepwise linear regression model with the Peripheral Artery Questionnaire as dependent variable, a significant effect of age, emotional functions, energy and drive functions, carrying out daily routine, as well as walking could be observed. This study identifies International Classification of Functioning, Disability and Health categories in the Brief Core Sets for ischemic heart diseases that show a significant effect on the ankle-brachial index and the Peripheral Artery Questionnaire score in patients with PAD. These categories provide fundamental information on functioning of patients with PAD and patient-centered outcomes for rehabilitation interventions.

Preliminary Internal Performance Data for a Variable-Ejector Assembly on the XJ79-GE-1 Turbojet Engine. II; Afterburning Configurations

NASA Technical Reports Server (NTRS)

Bloomer, Harry E.; Groesbeck, Donald E.

1957-01-01

Internal performance of an XJ79-GE-1 variable ejector was experimentally determined with the primary nozzle in two representative after-burning positions. Jet-thrust and air-handling data were obtained in quiescent air for 4 selected ejector configurations over a wide range of secondary to primary airflow ratios and primary-nozzle pressure ratios. The experimental ejector data are presented in both graphical and tabulated form.

The use of heart rate variability in assessing precompetitive stress in high-standard judo athletes.

PubMed

Morales, J; Garcia, V; García-Massó, X; Salvá, P; Escobar, R; Buscà, B

2013-02-01

The objective of this study is to examine the sensitivity to and changes in heart rate variability (HRV) in stressful situations before judo competitions and to observe the differences among judo athletes according to their competitive standards in both official and unofficial competitions. 24 (10 male and 14 female) national- and international-standard athletes were evaluated. Each participant answered the Revised Competitive State Anxiety Inventory (CSAI-2R) and their HRV was recorded both during an official and unofficial competition. The MANOVA showed significant main effects of the athlete's standard and the type of competition in CSAI-2R, in HRV time domain, in HRV frequency domain and in HRV nonlinear analysis (p<0.05). International-standard judo athletes have lower somatic anxiety, cognitive anxiety, heart rate and low-high frequency ratio than national-standard athletes (p<0.05). International-standard athletes have a higher confidence, mean RR interval, standard deviation of RR, square root of the mean squared difference of successive RR intervals, number of consecutive RR that differ by more than 5 ms, short-term variability, long-term variability, long-range scaling exponents and short-range scaling exponent than national-standard judo athletes. In conclusion, international-standard athletes show less pre-competitive anxiety than the national-standard athletes and HRV analysis is sensitive to changes in pre-competitive anxiety. © Georg Thieme Verlag KG Stuttgart · New York.

The influence of internal climate variability on heatwave frequency trends

NASA Astrophysics Data System (ADS)

E Perkins-Kirkpatrick, S.; Fischer, E. M.; Angélil, O.; Gibson, P. B.

2017-04-01

Understanding what drives changes in heatwaves is imperative for all systems impacted by extreme heat. We examine short- (13 yr) and long-term (56 yr) heatwave frequency trends in a 21-member ensemble of a global climate model (Community Earth System Model; CESM), where each member is driven by identical anthropogenic forcings. To estimate changes dominantly due to internal climate variability, trends were calculated in the corresponding pre-industrial control run. We find that short-term trends in heatwave frequency are not robust indicators of long-term change. Additionally, we find that a lack of a long-term trend is possible, although improbable, under historical anthropogenic forcing over many regions. All long-term trends become unprecedented against internal variability when commencing in 2015 or later, and corresponding short-term trends by 2030, while the length of trend required to represent regional long-term changes is dependent on a given realization. Lastly, within ten years of a short-term decline, 95% of regional heatwave frequency trends have reverted to increases. This suggests that observed short-term changes of decreasing heatwave frequency could recover to increasing trends within the next decade. The results of this study are specific to CESM and the ‘business as usual’ scenario, and may differ under other representations of internal variability, or be less striking when a scenario with lower anthropogenic forcing is employed.

Pronounced differences between observed and CMIP5-simulated multidecadal climate variability in the twentieth century

NASA Astrophysics Data System (ADS)

Kravtsov, Sergey

2017-06-01

Identification and dynamical attribution of multidecadal climate undulations to either variations in external forcings or to internal sources is one of the most important topics of modern climate science, especially in conjunction with the issue of human-induced global warming. Here we utilize ensembles of twentieth century climate simulations to isolate the forced signal and residual internal variability in a network of observed and modeled climate indices. The observed internal variability so estimated exhibits a pronounced multidecadal mode with a distinctive spatiotemporal signature, which is altogether absent in model simulations. This single mode explains a major fraction of model-data differences over the entire climate index network considered; it may reflect either biases in the models' forced response or models' lack of requisite internal dynamics, or a combination of both.