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Relevant bibliographies by topics / Variable stars

Academic literature on the topic 'Variable stars'

Author: Grafiati

Published: 4 June 2021

Last updated: 29 July 2024

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Journal articles on the topic "Variable stars"

1

Szeidl, B., M. Breger, A. N. Cox, R. E. Gershberg, M. Jerzykiewicz, L. N. Mavridis, L. N. Mirzoyan, et al. "27. Variable Stars (Etoiles Variables)." Transactions of the International Astronomical Union 20, no. 1 (1988): 257–92. http://dx.doi.org/10.1017/s0251107x00007197.

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The field of variable star research has become so broad and the amount of research to be reported on has grown so rapidly that it is a vain hope that a report of this kind, in a very limited space, could cover the whole field of research and could mention all the papers that have been published in the last three years. It is only hoped that this report presents the significant results achieved in the field of the most important aspects of variable star research. Some important subjects (e.g. cataclysmic variables) relevant to the variable star research are reviewed in the reports of other commissions. This is a consequence of the fact that the research has become very complex and the phenomena producing light variability belong to the field of interest of other commissions, too.

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2

Percy, J. R., L. Szabados, K. Oláh, N. N. Samus, Luis A. Balona, D. W. Kurtz, Nancy Remage Evans, et al. "27. Variable Stars (Etoiles Variables)." Transactions of the International Astronomical Union 22, no. 1 (1994): 243–76. http://dx.doi.org/10.1017/s0251107x00008051.

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3

Jerzykiewicz, M., L. A. Baiona, E. F. Guinan, Y. Kondo, D. W. Kurtz, M. Rodono, and J. Sahade. "Division V: Variable Stars: (Etoiles Variables)." Transactions of the International Astronomical Union 24, no. 1 (2000): 251–54. http://dx.doi.org/10.1017/s0251107x0000314x.

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This report covers the period July 1, 1996 (the closing date of the reports in the IAU Trans. 23A) through August 31, 1999. Since the reports of Commissions 27 and 42 that follow highlight the research made in the triennium, we limit ourselves here to organizational activities of the Division. The first three sections are devoted to the General Catalogue of Variable Stars (GCVS), the Information Bulletin on Variable Stars (IBVS), and the Archives of Unpublished Observations of Variable Stars, the important projects that serve us all. I am indebted to the authors, listed in the sections headings, for providing these summaries. The problems of naming and classifying variable stars, implicit in Sect. 2, are taken up in Sect. 5. The last section lists meetings sponsored by the Division.

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Guinan, Edward F., S. Balona, J. Christensen-Dalgaard, M. Jerzykiewicz, D. Kurtz, J. Sahade, and P. Szkody. "Division V: Variable Stars: (Etoiles Variables)." Transactions of the International Astronomical Union 25, no. 1 (2002): 265–67. http://dx.doi.org/10.1017/s0251107x00001528.

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Christensen-Dalsgaard, Jørgen, Conny Aerts, Carla Cacciari, Peter Cottrell, Ed Guinan, Petr Harmanec, Don Kurtz, et al. "Commission 27: Variable Stars: (Etoiles Variables)." Transactions of the International Astronomical Union 25, no. 1 (2002): 271–76. http://dx.doi.org/10.1017/s0251107x00001553.

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Percyy, John R. "Variable stars." Physics Teacher 31, no. 9 (December 1993): 541–43. http://dx.doi.org/10.1119/1.2343874.

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Kurtz, D. W., J. Christensen-Dalsgaard, C. Cacciari, P. Cottrell, P. Harmanec, M. Jerzykiewicz, J. Matthews, P. Moskalik, D. Sasselov, and D. Welch. "Commission 27: Variable Stars: (Les Etoiles Variables)." Transactions of the International Astronomical Union 24, no. 1 (2000): 255–58. http://dx.doi.org/10.1017/s0251107x00003151.

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For Commission 27 these triennial reports have traditionally been very compact literature reviews of all the fields relevant to our commission. For several triennia we have been discussing the relevance of them, and asking just who their readership is. It seems that only a few people read them, and fewer use them as introductions to the subject – supposedly one of their prime purposes. The major beneficiaries have been the writers, who have been forced to do three-year reviews of their subjects. The IAU EC gave us the option this triennium of a shorter, four-page report to which the majority of the SOC agreed.

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Christensen-Dalsgaard, Jørgen. "Commission 27: Variable Stars (Les Étoiles Variables)." Transactions of the International Astronomical Union 25, no. 2 (2007): 149–50. http://dx.doi.org/10.1017/s0251107x00026705.

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9

Warner, Brian. "Cataclysmic Variable Stars." Highlights of Astronomy 11, no. 1 (1998): 16–27. http://dx.doi.org/10.1017/s1539299600019924.

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The evolution of single stars on and away from the main sequence is well understood. A degenerate core is formed in a star as the star leaves the main sequence and expands to a giant with a radius typically 50 - 500 Ro . Observationally it is known that most stars are members of binary systems, and among these many have orbital periods less than 100 y. It can happen, therefore, that the expanding envelope of the primary of a binary system can reach to the secondary. As this happens, the primary fills its Roche tidal lobe and transfers matter to the secondary; if the primary has a radiative envelope the rate at which this occurs exceeds the Eddington limit of the secondary, which therefore repels the incoming gas, forming a common envelope around the two stars. Friction within the envelope causes the stars to spiral towards each other until the energy and angular momentum extracted from the binary orbit and transferred to the envelope are sufficient to eject the common envelope as a planetary nebula, leaving a short period binary comprising a white dwarf and a main sequence star.This mechanism of producing short period binaries containing white dwarfs, proposed by Ostriker and by Paczynski (1976), is the probable origin of the class of objects known as Cataclysmic Variable Stars (CVs), which encompass the classical novae, dwarf novae, novalike variables and a variety of related objects. Evidence has been accumulating for forty years (Crawford & Kraft 1956, Warner 1995a) that every CV consists of a secondary star (usually a dwarf, but a few systems contain giants) filling its Roche lobe and transferring mass to a white dwarf primary. In systems of normal chemical composition the orbital periods lie between 75 mins and ~250 d, with the majority having . A few hydrogen-free systems are known for which 17 mins < Porb < 50 mins. It should be noted that CVs are very compact binary systems: for h such a binary would fit inside the Sun.

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Baker, N., B. Szeidl, M. Breger, A. N. Cox, J. D. Fernie, A. M. van Genderen, R. E. Gershberg, et al. "27. Variable Stars." Transactions of the International Astronomical Union 19, no. 1 (1985): 277–311. http://dx.doi.org/10.1017/s0251107x00006398.

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The field of variable-star research is so broad that no report of this nature could possibly mention all the papers that have appeared in the last three years. It is hoped, however, that the reviews below include the most important work and identify the most significant trends. This report comprises ten sections on as many different research topics, each written by a different member of Commission 27. In addition there are (in Section 12) three short reports about ongoing activities of the commission. The commission president is very grateful to the authors of the individual contributions who have worked so conscientously.

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Dissertations / Theses on the topic "Variable stars"

1

Davey, Stephen. "Irradiation of the secondary star in cataclysmic variable stars." Thesis, University of Sussex, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.386388.

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Kube, Jens. "Indirect imaging of cataclysmic variable stars." Doctoral thesis, [S.l.] : [s.n.], 2002. http://webdoc.sub.gwdg.de/diss/2002/kube/kube.pdf.

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Thoroughgood, Timothy David. "The masses of cataclysmic variable stars." Thesis, University of Sheffield, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.419603.

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Marsh, T. R. "Emission lines in cataclysmic variable stars." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372891.

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Sahman, David. "The evolution of cataclysmic variable stars." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/21700/.

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Cataclysmic variables (CVs) are binary star systems comprising a white dwarf which is accreting material from a Roche-lobe filling companion, usually a late-main sequence or evolved star. The accreted material accumulates on the surface of the white dwarf and ultimately leads to a thermonuclear runaway explosion, called a nova eruption. There are ∼ 400 recorded novae and some have shown more than one eruption. These systems are the recurrent novae, and they are one of the leading progenitor candidates of Type Ia Supernovae. In this thesis, I describe how I used high speed spectroscopy to determine the component masses of the stars in the eclipsing recurrent nova CI Aquilae. The masses I determined suggest it is indeed a progenitor of a Type Ia supernova, and will explode in 10 Myr. The long term impact of nova events on the evolution of CVs is poorly understood, and may be the reason for the diversity of CV types observed at the same orbital period. One theory, known as hibernation theory, proposes that the nova event causes systems to cycle through the various classes of CVs, due to heating and bloating of the secondary. In the second part of this thesis, I undertook searches for nova shells around known CVs, in an effort to determine the frequency and life-cycle of novae. I examined over 150 systems and found one definite shell around V1315 Aquilae. I then used high–resolution spectroscopy to determine the mass and age of this shell. This is the first discovery of a nova shell around a novalike variable. By combining my search results with simulations and the results of other recent searches for nova shells, I find that the lifetime of the novalike state is broadly in line with the nova-induced cycle theory (hibernation theory).

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Wynn, Graham Anthony. "Accretion processes in cataclysmic variable stars." Thesis, University of Leicester, 1993. http://hdl.handle.net/2381/35833.

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Pretorius, Magaretha L. "Rapid oscillations in cataclysmic variable stars." Master's thesis, University of Cape Town, 2004. http://hdl.handle.net/11427/6103.

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Includes bibliographical references (p. 129-146).
Rapid quasi-coherent oscillations were detected in the optical light curves of 24 cataclysmic variable stars (CVS). In 12 of these systems (TU Men, WW Cet, HX Peg, BP CrA, BR Lup, HP Nor, AG Hya, TW Vir, PU CMa, V426 Ooph, V1193 Ori, and CR Boo) for the first time. The results contribute to the observational record of the phenomenology of dwarf nova oscillations (DNOs), quasi-periodic oscillations (QPOs), and longer period dwarf nova oscillations (lpDNOs), strengthen the correlation, valid over nearly six orders of magnitude in frequency, between the ratio of time scales of different classes of oscillations in white dwarf, neutron star, and black hole binaries, and show that the recently recognized lpDNOs occur fairly commonly in high mass transfer rate CVs.

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Ireland, Michael. "Optical interferometry and Mira variable stars /." Connect to full text, 2005. http://hdl.handle.net/2123/721.

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Ireland, Michael James. "Optical Interferometry and Mira Variable Stars." Thesis, The University of Sydney, 2005. http://hdl.handle.net/2123/721.

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This thesis describes the development of a red tip/tilt and fringe detection system at the Sydney University Stellar Interferometer (SUSI), modelling the instrumental performance and effects of seeing at SUSI, making observations of Mira variable stars and finally modelling the atmospheres of Mira variables with physically self-consistent models. The new SUSI tip/tilt system is based around a CCD detector and has been successfully used to both track the majority of tip/tilt power in median seeing at an R magnitude of 4.5, and to provide seeing measures for post processing. The new fringe-detection system rapidly scans 33 to 140 $\mu$m in delay and detects the fringes using two avalanche-photodiodes. It has been used to acquire fringe data, provide user feedback and to track the fringe group-delay position. The system visibility (fringe visibility for a point source) and throughput were found to be consistent with models of the SUSI optical beam train. Observations were made of a variety of sources, including the Mira variables R Car and RR Sco, which were observed in two orthogonal polarization states. These measurements were the first successful use of Optical Interferometric Polarimetry (OIP), and enabled scattered light to be separated from bright photospheric flux. Dust scattering was found to originate from a thin shell 2-3 continuum radii from these stars, with an optical depth of 0.1 to 0.2 at 900 nm. Physical models of Mira variables including dust formation were developed, providing consistent explanations for these results as well as many other photometric and interferometric observations.

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Ireland, Michael James. "Optical Interferometry and Mira Variable Stars." University of Sydney. Physics, 2005. http://hdl.handle.net/2123/721.

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This thesis describes the development of a red tip/tilt and fringe detection system at the Sydney University Stellar Interferometer (SUSI), modelling the instrumental performance and effects of seeing at SUSI, making observations of Mira variable stars and finally modelling the atmospheres of Mira variables with physically self-consistent models. The new SUSI tip/tilt system is based around a CCD detector and has been successfully used to both track the majority of tip/tilt power in median seeing at an R magnitude of 4.5, and to provide seeing measures for post processing. The new fringe-detection system rapidly scans 33 to 140 $\mu$m in delay and detects the fringes using two avalanche-photodiodes. It has been used to acquire fringe data, provide user feedback and to track the fringe group-delay position. The system visibility (fringe visibility for a point source) and throughput were found to be consistent with models of the SUSI optical beam train. Observations were made of a variety of sources, including the Mira variables R Car and RR Sco, which were observed in two orthogonal polarization states. These measurements were the first successful use of Optical Interferometric Polarimetry (OIP), and enabled scattered light to be separated from bright photospheric flux. Dust scattering was found to originate from a thin shell 2-3 continuum radii from these stars, with an optical depth of 0.1 to 0.2 at 900 nm. Physical models of Mira variables including dust formation were developed, providing consistent explanations for these results as well as many other photometric and interferometric observations.

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Books on the topic "Variable stars"

1

Michel, Petit. Variable stars. Chichester: Wiley, 1987.

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2

Hoffmeister, Cuno, Gerold Richter, and Wolfgang Wenzel. Variable Stars. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-82269-8.

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3

Good, Gerry A. Observing Variable Stars. London: Springer London, 2003. http://dx.doi.org/10.1007/978-1-4471-0055-3.

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4

Warner, Brian. Cataclysmic variable stars. Cambridge: Cambridge University Press, 1995.

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5

Percy, John R. Understanding variable stars. Cambridge: Cambridge University Press, 2007.

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6

Colloquium, International Astronomical Union. Physics of luminous blue variables: Proceedings of the 113th Colloquium of the International Astronomical Union, held at Val Morin, Quebec Province, Canada, August 15-18, 1988. London: Kluwer Academic, 1989.

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7

Sovet, Akademiya Nauk SSSR Astronomicheskii. General catalogue of variable stars. 4th ed. Moscow: Nauka, 1985.

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8

Griffiths, Martin. Observer's Guide to Variable Stars. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-030-00904-5.

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9

Broens, Eric. Variable stars: Visual light curves. Brugge, Belgium: Vereniging voor Sterrenkunde, 2000.

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Kolman, Roger S. Observe and understand variable stars. [Washington, D.C.]: Astronomical League, 1999.

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Book chapters on the topic "Variable stars"

1

McNally, Derek. "Variable Stars (Etoiles Variables)." In Reports on Astronomy, 247–80. Dordrecht: Springer Netherlands, 1991. http://dx.doi.org/10.1007/978-94-011-3364-7_19.

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2

Hoffmeister, Cuno, Gerold Richter, and Wolfgang Wenzel. "Eclipsing Stars." In Variable Stars, 198–220. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-82269-8_4.

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Hoffmeister, Cuno, Gerold Richter, and Wolfgang Wenzel. "General Introduction." In Variable Stars, 1–25. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-82269-8_1.

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Hoffmeister, Cuno, Gerold Richter, and Wolfgang Wenzel. "Pulsating Variables." In Variable Stars, 26–78. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-82269-8_2.

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Hoffmeister, Cuno, Gerold Richter, and Wolfgang Wenzel. "Eruptive Variables." In Variable Stars, 79–197. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-82269-8_3.

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Hoffmeister, Cuno, Gerold Richter, and Wolfgang Wenzel. "Supplement to the Classification." In Variable Stars, 221–40. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-82269-8_5.

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Hoffmeister, Cuno, Gerold Richter, and Wolfgang Wenzel. "The Discovery of Variable Stars." In Variable Stars, 241–60. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-82269-8_6.

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Hoffmeister, Cuno, Gerold Richter, and Wolfgang Wenzel. "The Significance of Variable Stars for Research on the Structure of the Galaxy and Stellar Evolution." In Variable Stars, 261–73. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-82269-8_7.

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Hoffmeister, Cuno, Gerold Richter, and Wolfgang Wenzel. "Observational Methods and Organizations." In Variable Stars, 274–91. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-82269-8_8.

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Hoffmeister, Cuno, Gerold Richter, and Wolfgang Wenzel. "Literature." In Variable Stars, 293–313. Berlin, Heidelberg: Springer Berlin Heidelberg, 1985. http://dx.doi.org/10.1007/978-3-642-82269-8_9.

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Conference papers on the topic "Variable stars"

1

Fritzius, Robert S. "A Ritzian interpretation of variable stars." In The fifth huntsville gamma-ray burst symposium. AIP, 2000. http://dx.doi.org/10.1063/1.1361608.

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Córdova, France A., Edwin F. Ladd, and Keith O. Mason. "The winds in cataclysmic variable stars." In AIP Conference Proceedings Volume 144. AIP, 1986. http://dx.doi.org/10.1063/1.35661.

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Varadi, Mihaly, Laurent Eyer, Stefan Jordan, Nami Mowlavi, Detlev Koester, Joyce Ann Guzik, and Paul A. Bradley. "Detecting Short Period Variable Stars with Gaia." In STELLAR PULSATION: CHALLENGES FOR THEORY AND OBSERVATION: Proceedings of the International Conference. AIP, 2009. http://dx.doi.org/10.1063/1.3246507.

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Joner, Michael D., and Eric G. Hintz. "Interactive online archive for short-period variable stars." In Astronomical Telescopes & Instrumentation, edited by Peter J. Quinn. SPIE, 1998. http://dx.doi.org/10.1117/12.316503.

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Greco, Claudia, Nami Mowlavi, Laurent Eyer, Maxime Spano, Mihaly Varadi, Gilbert Burki, Joyce Ann Guzik, and Paul A. Bradley. "Searching for Variable Stars in Galactic Open Clusters." In STELLAR PULSATION: CHALLENGES FOR THEORY AND OBSERVATION: Proceedings of the International Conference. AIP, 2009. http://dx.doi.org/10.1063/1.3246502.

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Soszyński, Igor, Joyce Ann Guzik, and Paul A. Bradley. "The OGLE-III Catalog of Variable Stars 100 k Pulsating Stars in the LMC." In STELLAR PULSATION: CHALLENGES FOR THEORY AND OBSERVATION: Proceedings of the International Conference. AIP, 2009. http://dx.doi.org/10.1063/1.3246499.

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Kwiecinska, K., M. Biskup, K. Malek, L. Mankiewicz, B. Pilecki, M. Sokolowski, D. Szczygiel, and G. Wrochna. "Variable stars study in "Pi of the Sky" project." In SPIE Proceedings, edited by Ryszard S. Romaniuk. SPIE, 2006. http://dx.doi.org/10.1117/12.675019.

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Sarro, Luis Manuel, Albert Domingo, J. Miguel Mas-Hesse, Enrique Solano, and Raúl P. Gutierrez. "Learning from optically variable stars: the OMC scientific case." In ADA-III - Astronomical Data Analysis III Conference. BCS Learning & Development, 2004. http://dx.doi.org/10.14236/ewic/ada-iii2004.4.

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Chen, Kwan-Yu. "Photometry of selected variable stars at the South Pole." In Astrophysics in Antarctica. AIP, 1990. http://dx.doi.org/10.1063/1.39018.

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Kenyon, Scott J. "Accretion disk eruptions in the FU Orionis variable stars." In The tenth astrophysics conference: Cosmic explosions. AIP, 2000. http://dx.doi.org/10.1063/1.1291743.

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Reports on the topic "Variable stars"

1

Alcock, C., D. Alves, T. Axelrod, D. Bennett, S. Marshall, D. Minniti, and M. Pratt. The MACHO project: Microlensing and variable stars. Office of Scientific and Technical Information (OSTI), October 1996. http://dx.doi.org/10.2172/490163.

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Purdue, Patricia. MACHO project LMC variable star inventory: Aperiodic blue variables. Office of Scientific and Technical Information (OSTI), May 1996. http://dx.doi.org/10.2172/576759.

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Purdue, P. The MACHO Project LMC variable star inventory: Aperiodic blue variables. Office of Scientific and Technical Information (OSTI), December 1995. http://dx.doi.org/10.2172/195743.

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Sherfy, Robert, and John D. Tanner. Total Environmental Control Systems, Soft-Start and Soft-Start Variable Capacity Air Conditioners. Fort Belvoir, VA: Defense Technical Information Center, November 1987. http://dx.doi.org/10.21236/ada210719.

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Whitaker, Stephen. Rocky intertidal community monitoring at Channel Islands National Park: 2018–19 annual report. National Park Service, August 2023. http://dx.doi.org/10.36967/2299674.

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Channel Islands National Park includes the five northern islands off the coast of southern California (San Miguel, Santa Rosa, Santa Cruz, Anacapa, and Santa Barbara Islands) and the surrounding waters out one nautical mile. There are approximately 176 miles of coastline around the islands, about 80% of which is composed of rock. The diversity and undisturbed nature of the tidepools of this rocky coastline were recognized as special features of the islands in the enabling legislation. To conserve these communities unimpaired for future generations, the National Park Service has been monitoring the rocky intertidal communities at the islands since 1982. Sites were established between 1982 and 1998. Site selection considered visitation, accessibility, presence of representative organisms, wildlife disturbance, and safety. This report summarizes the 2018–2019 sampling year efforts (from November 2018 to April 2019) and findings of the Channel Islands National Park Rocky Intertidal Community Monitoring Program. Specific monitoring objectives are 1) to determine the long-term trends in percent cover of key sessile organisms in the rocky intertidal ecosystem, and 2) to determine population dynamics of black abalone (Haliotis cracherodii), owl limpets (Lottia gigantea), and ochre sea stars (Pisaster ochraceus). Objectives were met by monitoring percent cover of core species in target intertidal zones using photoplots and transects, and by measuring size frequency and abundance of black abalone, owl limpets, and sea stars using fixed plots or timed searches. Twelve key species or assemblages, as well as the substrate, tar, have been monitored twice per year at 21 sites on the five park islands as part of the rocky intertidal community monitoring program. Fixed photoplots were used to monitor the percent cover of thatched and acorn barnacles (Tetraclita rubescens, Balanus glandula/Chthamalus spp., respectively), mussels (Mytilus californianus), rockweeds (Silvetia compressa, and Pelvetiopsis californica (formerly Hesperophycus californicus), turfweed (Endocladia muricata), goose barnacles (Pollicipes polymerus) and tar. Point-intercept transects were used to determine the percent cover of surfgrass (Phyllospadix spp.). Information about size distribution (i.e., “size frequency” data) was collected for owl limpets in circular plots. Size distribution and relative abundance of black abalone and ochre sea stars were determined using timed searches. The maximum number of shorebirds and pinnipeds seen at one time were counted at each site. The number of concession boat visitors to the Anacapa tidepools was collected and reported. All sites were monitored in 2018–2019. This was the third year that we officially reduced our sampling interval from twice per year (spring and fall) to once in order to streamline the program and allow for the implementation of additional protocols. Weather conditions during the site visits were satisfactory, but high wind coupled with strong swell and surge limited or prevented the completion of some of the abalone and sea star searches. The percent cover for most key species or assemblages targeted in the photoplots was highly variable among sites. Mussel (Mytilus californianus) cover remained below average at Anacapa and Santa Barbara Islands. Record or near record low abundances for Mytilus were measured at Middle West Anacapa (Anacapa Island), Harris Point (San Miguel Island), Prisoner’s Harbor (Santa Cruz Island), and Sea Lion Rookery (Santa Barbara Island) sites. The only site that appeared to have above average Mytilus cover was Scorpion Rock on Santa Cruz Island. All other sites had mussel cover near or below the long-term mean. Qualitatively, Mytilus recruitment appeared low at most sites. Both rockweed species, Silvetia compressa and Pelvetiopsis californica (formerly Hesperophycus californicus), continued to decrease markedly in abundance this year at the majority of sites compared to combined averages for previous years. Fossil Reef and Northwest-Talcott on Santa Rosa Island, Sea Lion Rookery on Santa Barbara Island, and South Frenchy’s Cove on Anacapa Island were the only sites that supported Silvetia cover that was near the long-term mean. No sites exhibited above average cover of rockweed. Extremely high levels of recruitment for Silvetia and Pelvetiopsis were documented at many sites. Most sites exhibited marked declines in S. compressa abundances beginning in the early 2000s, with little recovery observed for the rockweed through this year. Barnacle (Chthamalus/Balanus spp.) cover fell below the long-term means at all islands except Anacapa, where barnacle cover was slightly above average. Endocladia muricata abundances remained comparable to the grand mean calculated for previous years at Santa Barbara, Santa Cruz, and Santa Rosa Islands, while cover of the alga decreased slightly below the long-term means at Anacapa and San Miguel Islands. Black abalone (Haliotis cracherodii) abundances at the islands remain less than one percent of 1985 population levels. Zero abalone were found throughout the entire site at Landing Cove on Santa Barbara Island and South Frenchy’s Cove on Anacapa Island. Above average abundances relative to the long-term mean generated from post-1995 data were observed at all but five sites. Juvenile black abalone were seen at all islands except Santa Barbara. Ochre sea star (Pisaster ochraceus) populations crashed in 2014 at all monitoring sites due to Sea Star Wasting Syndrome, an illness characterized by a suite of symptoms that generally result in death. The mortality event was widely considered to be the largest mortality event for marine diseases ever seen. Beginning in June 2013, the disease swiftly and significantly impacted P. ochraceus (among other species of sea stars) populations along the North American Pacific coast from Alaska to Baja California, Mexico. By the beginning of 2014, P. ochraceus abundances had declined by >95% at nearly all Channel Islands long-term intertidal monitoring sites, in addition to numerous other locations along the West Coast. At various times during the past decade, extremely high abundances (~ 500 P. ochraceus) have been observed at multiple sites, and most locations have supported >100 sea stars counted during 30-minute site-wide searches. This year, abundances ranged 0–13 individuals per site with all but one site having fewer than 10 P. ochraceus seen during routine searches. Insufficient numbers of sea stars were seen to accurately estimate the size structure of P. ochraceus populations. Only two juveniles (i.e., <50 mm) were observed at all sites combined. Giant owl limpet densities in 2018–2019 were comparable or slightly above the long-term mean at seven sites. Exceptionally high densities were measured at Northwest-Talcott on Santa Rosa Island, Otter Harbor on San Miguel Island, and Willows Anchorage on Santa Cruz Island. The sizes of L. gigantea this year varied among sites and islands. The smallest L. gigantea were observed at Otter Harbor followed closely by Willows Anchorage and Anacapa Middle West, and the largest were seen at Northwest-Talcott. Temporally, the mean sizes of L. gigantea in 2018–2019 decreased below the long-term mean at each island except Anacapa. Surfgrasses (Phyllospadix spp.) are typically monitored biannually at two sites each on Santa Cruz and Santa Rosa Islands. Beginning in 2015, all transects at each of the monitoring sites were only sampled once per year. At East Point on Santa Rosa Island, the conditions were not conducive to sampling the surfgrass transects, but qualitatively, percent cover of surfgrass appeared to be near 100% on all three transects. Relative to past years, cover of surfgrass increased above the long-term mean at Fraser Cove on Santa Cruz Island, fell slightly below the mean at Trailer on Santa Cruz Island, and remained approximately equivalent to the mean at the two Santa Rosa Island sites. Overall, the abundance and diversity of shorebirds in 2018–2019 at all sites appeared similar to observations made in recent years, with the exception of elevated numbers of brown pelicans (Pelecanus occidentalis) observed at East Point on Santa Rosa Island. Black oystercatchers (Haematopus bachmani) were the most ubiquitous shorebird seen at all sites. Black turnstones (Arenaria melanocephala) were not common relative to past years. Pinniped abundances remained comparable in 2018–2019 to historical counts for all three species that are commonly seen at the islands. Harbor seals (Phoca vitulina) were seen in the vicinity of eight sites this year. As in past years, harbor seals were most abundant at Otter Harbor and Harris Point on San Miguel Island. Elephant seals (Mirounga angustirostris) were seen at six sites during the year, where abundances ranged 1–5 individuals per location. California sea lions (Zalophus californianus) were common at Santa Barbara Island; 117 individuals were observed at Sea Lion Rookery. Sea lion abundances were higher than usual at Harris Point (N = 160) and Otter Harbor (N = 82) on San Miguel Island. Relative to past years, abundances this year were considered average at other locations.

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Glancy, David, Robert Kurtzman, and Lara P. Loewenstein. On commercial construction activity's long and variable lags. Federal Reserve Bank of Cleveland, June 2024. http://dx.doi.org/10.26509/frbc-wp-202414.

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We use microdata on the phases of commercial construction projects to document three facts regarding time-to-plan lags: (1) plan times are long - about 1.5 years - and highly variable, (2) roughly 40 percent of projects are abandoned in planning, and (3) property price appreciation reduces the likelihood of abandonment. We construct a model with endogenous planning starts and abandonment that matches these facts. The model has the testable implication that supply is more elastic when there are more "shovel ready" projects available to advance to construction. We use local projections to validate that this prediction holds in the cross-section for US cities.

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Thomas, Tucker, and Cowell. PR-283-10204-R01 Prevent Variable Guide Vane Lock-up - Solar Gas Turbines with Intermittent Operation. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), January 2016. http://dx.doi.org/10.55274/r0010856.

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A study was completed to demonstrate that a guide vane field refurbishment process and improved maintenance practices are effective at preventing corrosion and lock-up of the guide vanes of Solar�s Taurus 60-7802S gas turbine operated in intermittent duty. A Taurus 60 engine located at Dominion�s Crayne compressor station was refurbished and operated over a five year period using maintenance practices to slow the build-up of corrosion. The visible condition of the VGV assembly on this Test Unit was monitored and the guide vane actuator force measured to assess if corrosion build-up was occurring. A second co-located Taurus 60 served as a Control Unit to validate that the environment and operating profile were conducive to corrosion build-up. The Control Unit was not modified with the exception that electric actuators were installed on both units so that the VGV actuator force could be measured. The engines logged over 18,000 hours of operation during the test period after which, both units were pulled for overhaul. A detailed inspection and assessment was completed with extensive photographic documentation of the condition of the hardware. The actuator force measured during the start sequence for each of the engines was compared. The Test Unit actuator force varied from 180 to 265 lbf, while the Control Unit had a considerably larger variation of 170 to 315 lbf. The Control Unit suffered a guide vane lock-up event in June of 2014.

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8

Villela, Luiz Arruda, and Vicente Fretes Cibils. The Fiscal Impact of the International Financial Crisis on Latin American and Caribbean Economies. Inter-American Development Bank, October 2008. http://dx.doi.org/10.18235/0009070.

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The main objective of this Technical Note is to provide a simple framework to determine the short-term fiscal impact of the international financial crisis on Latin American and Caribbean (LAC) countries, i.e., fiscal financing needs/gap by country (or fiscal liquidity impact). In addition, it will provide a framework to evaluate fiscal sustainability by country (or fiscal solvency impact). In both cases, and depending of the particular country under analysis, transmission mechanisms (variables) will be identified, and sensitivity analysis will be carried out to determine the robustness of their impact. Given that LAC economies are quite heterogeneous, the standard framework will require adjustments to reflect each individual case under analysis. The Note also proposes to start the analysis on those countries with relatively weakest initial conditions as defined by countries with primary and overall fiscal deficits.

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Lieth, J. Heiner, Michael Raviv, and David W. Burger. Effects of root zone temperature, oxygen concentration, and moisture content on actual vs. potential growth of greenhouse crops. United States Department of Agriculture, January 2006. http://dx.doi.org/10.32747/2006.7586547.bard.

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Soilless crop production in protected cultivation requires optimization of many environmental and plant variables. Variables of the root zone (rhizosphere) have always been difficult to characterize but have been studied extensively. In soilless production the opportunity exists to optimize these variables in relation to crop production. The project objectives were to model the relationship between biomass production and the rhizosphere variables: temperature, dissolved oxygen concentration and water availability by characterizing potential growth and how this translates to actual growth. As part of this we sought to improve of our understanding of root growth and rhizosphere processes by generating data on the effect of rhizosphere water status, temperature and dissolved oxygen on root growth, modeling potential and actual growth and by developing and calibrating models for various physical and chemical properties in soilless production systems. In particular we sought to use calorimetry to identify potential growth of the plants in relation to these rhizosphere variables. While we did experimental work on various crops, our main model system for the mathematical modeling work was greenhouse cut-flower rose production in soil-less cultivation. In support of this, our objective was the development of a Rose crop model. Specific to this project we sought to create submodels for the rhizosphere processes, integrate these into the rose crop simulation model which we had begun developing prior to the start of this project. We also sought to verify and validate any such models and where feasible create tools that growers could be used for production management. We made significant progress with regard to the use of microcalorimetry. At both locations (Israel and US) we demonstrated that specific growth rate for root and flower stem biomass production were sensitive to dissolved oxygen. Our work also identified that it is possible to identify optimal potential growth scenarios and that for greenhouse-grown rose the optimal root zone temperature for potential growth is around 17 C (substantially lower than is common in commercial greenhouses) while flower production growth potential was indifferent to a range as wide as 17-26C in the root zone. We had several set-backs that highlighted to us the fact that work needs to be done to identify when microcalorimetric research relates to instantaneous plant responses to the environment and when it relates to plant acclimation. One outcome of this research has been our determination that irrigation technology in soilless production systems needs to explicitly include optimization of oxygen in the root zone. Simply structuring the root zone to be “well aerated” is not the most optimal approach, but rather a minimum level. Our future work will focus on implementing direct control over dissolved oxygen in the root zone of soilless production systems.

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Knaepen, Hanne. Climate risks in Tunisia: Challenges to adaptation in the agri-food system. European Centre for Development Policy Management, February 2021. http://dx.doi.org/10.55317/casc009.

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Tunisia’s agricultural system is central to the stability of the country, but it is also extremely prone to climate risks such as droughts and reduced or more variable rainfall. It is predicted that agricultural yields from key crops like wheat and olives will decline. These climate risks on Tunisia’s agricultural and wider food system can lead to socioeconomic instability and potentially cause security risks. Furthermore, these risks can have knock-on effects that cross national borders, sectors and systems. Tunisia’s capacity to adapt to climate change is undermined by three sets of political, governance and socio-economic factors, or so-called ‘climate-related development risks’, namely (1) governance and policy coherence challenges; (2) food import dependency and an export-oriented agri-food system; and (3) territorial inequalities. These factors contribute, directly or indirectly, to the likelihood of cascading climate risks that start with Tunisia’s agri-food system. Due to the country’s reduced adaptive capacity, climate risks in Tunisia’s agri-food system can have an impact on Europe through trade and supply chains, security relations, financial markets, international aid operations as well as migration patterns. It is key that the European Union recognises these risks in its Green Deal and adaptation efforts, as well as in a much wider group of policies, ranging from trade to migration.

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