Relevant bibliographies by topics / Very long baseline interferometry

Academic literature on the topic 'Very long baseline interferometry'

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Published: 4 June 2021
Last updated: 29 July 2024

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Journal articles on the topic "Very long baseline interferometry"

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Schilizzi, R. T. "Very long baseline interferometry." Radio Science 21, no. 4 (July 1986): 665–79. http://dx.doi.org/10.1029/rs021i004p00665.

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Moran, J. M. "Very Long Baseline Interferometry." Highlights of Astronomy 8 (1989): 553–54. http://dx.doi.org/10.1017/s1539299600008303.

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The technique of very long baseline interferometry (VLBI) has undergone two decades of steady growth and refinement since its inception in 1967. In the beginning, only crude measurements of visibility on single baselines were possible. Now 18-station arrays have been used to produce images with dynamic ranges exceeding 2000:1; relative motions of cosmic masers have been tracked at the microarcsecond level of accuracy; and angular size measurements have been made with baseline lengths up to 2 two earth diameters with an orbiting satellite as a receiving element.
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McAlister, Harold A. "Overview of Multiple–Aperture Interferometry Binary Star Results from the Northern Hemisphere." Proceedings of the International Astronomical Union 2, S240 (August 2006): 35–44. http://dx.doi.org/10.1017/s1743921307003778.

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AbstractLong-baseline optical interferometry (LBI) can nearly close the gap in selection space between astrometric and spectroscopic detection of binary star systems, bringing the complementary powers of astrometry and spectroscopy to bear on a complete dynamical understanding of such systems, particularly including the determination of the masses of the individual stellar components. In the case of double-lined spectroscopic systems, their resolution by long-baseline interferometry also yields the orbital parallax and hence the luminosities of the individual stars. In some of these cases, the angular diameters of one or more components are accessible, and so a complete specification of a star in terms of its mass, radius and luminosity is made.The northern hemisphere is now equipped with several interferometers of unprecedented capability in terms of their baseline sizes, numbers of telescopes and telescope apertures. These instruments, most notably the Palomar Testbed Interferometer at Mt. Palomar Observatory, have produced very significant results of a number of interesting systems fulfilling interferometry's promise to produce fundamental astrophysical data at levels of accuracy that challenge or confirm astrophysical theory.This paper presents basic principles of long-baseline interferometric study of binary stars and summarizes results from northern interferometers with specific examples of their broad impact on binary star astronomy.
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Schilizzi, R. T. "Very Long Baseline Interferometry (VLBI)." Europhysics News 19, no. 4 (1988): 46–52. http://dx.doi.org/10.1051/epn/19881904046.

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Stee, Ph, D. Bonneau, F. Morand, D. Mourard, and F. Vakili. "Current studies and future prospects in stellar-structure imaging with the GI2T." Symposium - International Astronomical Union 176 (1996): 191–98. http://dx.doi.org/10.1017/s0074180900083224.

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The capability of optical long baseline interferometry for measuring the angular diameter of stars or binary separation is now well established. However, for the imaging of photospheric disk structures one needs very long baseline interferometers operated in the multi-telescope phase-closure technique. In this paper we will stress the capability of spectro-interferometric measurements to constrain the physics of hot stars. We will report our study of the interacting binary, β Lyrae, and the mass-losing Be star γ Cassiopeiae. We will look at the interpretation of both the modulus and phase data recorded by the long baseline interferometer GI2T in the southern France. The performances and limitations of spectro-interferometric techniques will also be discussed through some of the most exciting prospects within the reach of current interferometers.
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Chesneau, O., K. Rousselet-Perraut, and F. Vakili. "Interferometry and Stellar Magnetism." International Astronomical Union Colloquium 175 (2000): 174–77. http://dx.doi.org/10.1017/s0252921100055792.

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AbstractThe classical detection of magnetic fields in Be stars remains a challenge due to the sensitivity threshold and geometrical cancelation of the field effects. We propose to study the Zeeman effect using Spectro-Polarimetric INterferometry (SPIN) which consists of the simultaneous use of polarimetry and very high angular resolution provided by long baseline interferometers. As monitoring of the instrumental polarisation is mandatory in order to calibrate interferometric observations in any case, the polarised signal is a natural by-product of interferometers. This method will be tested on the GI2T interferometer thanks to its high spectral resolution and its polarimetric capabilities.
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Tomasi, P., T. Clark, and J. Campbell. "Measurement technique. Very long baseline interferometry." Journal of Geodynamics 25, no. 3-4 (May 1998): 179–93. http://dx.doi.org/10.1016/s0264-3707(97)00034-3.

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Robertson, Douglas S. "Geophysical applications of very-long-baseline interferometry." Reviews of Modern Physics 63, no. 4 (October 1, 1991): 899–918. http://dx.doi.org/10.1103/revmodphys.63.899.

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Carter, W. E., and D. S. Robertson. "Very-Long-Baseline Interferometry Applied to Geophysics." Symposium - International Astronomical Union 156 (1993): 133–44. http://dx.doi.org/10.1017/s0074180900173115.

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Very-long-baseline Interferometry (VLBI) has opened for study a broad new spectrum of geophysical phenomena including: direct observation of the tectonic motions and deformations of the Earth's crustal plates, observations of unprecedented detail of the variations in the rotation of the Earth, and direct measurement of the elastic deformations of the Earth in response to tidal forces. These new measurements have placed significant constraints on models of the interior structure of the Earth; for example, measurements of the variations in the Earth's nutation have been shown to be particularly sensitive to the shape of the core-mantle boundary. The VLBI measurements will allow us to construct a global reference frame accurate at the centimeter level. Such a frame will be essential to studying long-term global changes, especially those changes related to sea-level variations as recorded by tide gauge measurements.
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ACCIOLY, ANTONIO, JOSÉ HELAYËL-NETO, and ESLLEY SCATENA. "PHOTON MASS AND VERY LONG BASELINE INTERFEROMETRY." International Journal of Modern Physics D 19, no. 14 (December 2010): 2393–403. http://dx.doi.org/10.1142/s021827181001844x.

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A relation between the photon mass, its frequency, ν, and the deflection parameter, γ, determined by experimentalists (that characterizes the contribution of space curvature to gravitational deflection) is found. This amazing result allows us to conclude that the knowledge of the parameters ν and γ is all we need to set up gravitational bounds on the photon mass. By considering as inputs the most recent measurements of the solar gravitational deflection of radio waves obtained via the Very Long Baseline Interferometry, upper bounds on the photon mass are estimated.
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Dissertations / Theses on the topic "Very long baseline interferometry"

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Howard, P. D. "Very Long Baseline Interferometry and earth rotation parameters." Thesis, University of Nottingham, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.373809.

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Peterson, William M. "Very long baseline interferometry of evolved binary systems." Diss., University of Iowa, 2011. https://ir.uiowa.edu/etd/1056.

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Our understanding of the magnetic fields of stars is nearly monopolized by knowledge of our own sun. Very-long baseline radio interferometry (VLBI) provides a means of directly imaging the radio coronae of other stars at a high enough resolution to discern discrete features, something not possible with other observational methods. It also allows the highest positional accuracy of any observational method available. This thesis details the VLBI study of two nearby radio-loud stars in close binary systems. Both systems were observed at numerous epochs spaced over a range of several months with the global-scale radio interferometer array the VLBA-HSA. These observations were combined with archival data from the National Radioastronomy Observatory (NRAO) Archive. The resulting positions, as well as previously published positions, were used to calculate a least-squares solution for all the orbital and astrometric parameters of both systems. This made it possible to determine the position of the physical star with respect to the radio emission in each image. The images of both stars were found to conform to theoretical emission produced by a model dipolar magnetosphere with a filled or partially-filled coronal loop.
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Kemball, Athol James. "Data reduction techniques for Very Long Baseline Interferometric spectropolarimetry." Thesis, Rhodes University, 1993. http://hdl.handle.net/10962/d1005242.

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This thesis reports the results of an investigation into techniques for the calibration and imaging of spectral line polarization observations in Very Long Baseline Interferometry (VLBI). A review is given of the instrumental and propagation effects which need to be removed in the course of calibrating such obervations, with particular reference to their polarization dependence. The removal of amplitude and phase errors and the determination of the instrumental feed response is described. The polarization imaging of such data is discussed with particular reference to the case of poorly sampled cross-polarization data. The software implementation of the algorithms within the Astronomical Image Processing System (AlPS) is discussed and the specific case of spectral line polarization reduction for data observed using the MK3 VLBI system is considered in detail. VLBI observations at two separate epochs of the 1612 MHz OH masers towards the source IRC+ 10420 are reduced as part of this work. Spectral line polarization maps of the source structure are presented, including a discussion of source morphology and variability. The source is sigmficantly circularly polarized at VLBI resolution, but does not display appreciable linear polarization. A proper motion study of the circumstellar envelope is presented, which supports an ellipsoidal kinematic model with anisotropic radial outflow. Kinematic modelling of the measured proper motions suggests a distance to the source of ~ 3 kpc. The cirumstellar magnetic field strength in the masing regions is determined as 1-3 mG, assuming Zeeman splitting as the polarization mechanism.
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Momjian, Emmanuel. "Sensitive very long baseline interferometry studies of interacting/merging galaxies." Lexington, Ky. : [University of Kentucky Libraries], 2003. http://lib.uky.edu/ETD/ukyphys2003d00108/EMthesis.pdf.

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Thesis (Ph. D.)--University of Kentucky, 2003.
Title from document title page (viewed onJune 1, 2004). Document formatted into pages; contains ix, 106 leaves : ill. (some col.). Includes abstract and vita. Includes bibliographical references (p. 99-104).
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Perez-Torres, Miguel ©¹ngel. "Radioemision dy supernovas y astrometria de alta precision = radio emission from supernovae and high precision astrometry / memoria presentada por Miguel Angel Perez Torres." Link to ADS abstract, 1999. http://adsabs.harvard.edu//abs/1999PhDT........11P.

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Richter, Laura. "A VLBI polarisation study of 43 GHZ SiO masers towards VY CMA /." Link to this resource, 2005. http://eprints.ru.ac.za/784/.

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Richter, Laura. "A VLBI polarisation study of 43 GHZ SiO masers towards VY CMA." Thesis, Rhodes University, 2006. http://hdl.handle.net/10962/d1005284.

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This thesis reports the calibration, imaging and analysis of one epoch of VLBI observations of the v (italics) = J (italics) = 1-0 transition of SiO towards VY CMa. Full polarisation information was recorded, allowing high resolution synthesis maps of each of the four Stokes parameters to be produced. A total of 81 maser components were extracted from the total intensity map, each approximately 1 mas in size. The emission spans approximately 100 x 80 mas in right ascension and declination and is concentrated to the east. The maser component positions were fitted to a ring of radius ~ 3.2R₊ (italics), or 7.2 x 1O¹⁴ cm for a stellar distance of 1.5 kpc. If the stellar position is assumed to be the centre of this ring then almost all of the maser components fall within the inner dust shell radius, which is at ~ 5R (italics)ϰ All of the maser components fall between 1.5R (italics)ϰ and 6R (italics)ϰ. A velocity gradient with position angle was observed in the sparsely filled western region of the maser ring. If interpreted as evidence of shell rotation, this gradient implies a rotational velocity of v (italics) rot (subscirpt) sin i (italics) = 18 km.s⁻¹. The fractional circular and linear polarisations of the maser spots were derived from the Stokes parameter maps. The mean fractional circular polarisation of the masers components was ~ 2 percent and the median fractional linear polarisation was ~ 6 percent, with many spots displaying over ~ 30 percent linear polarisation. The mean circular polarisation implies a magnetic field of ~ 4 G in the SiO maser region if the polarisation is due to Zeeman splitting. Two maser components display a rotation of linear polarisation position angle with velocity, possibly implying a connection between the magnetic field and the velocity field variations in the region of these components.
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Lenc, Emil. "Studies of radio galaxies and starburst galaxies using wide-field, high spatial resolution radio imaging." Swinburne Research Bank, 2009. http://hdl.handle.net/1959.3/48503.

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Thesis (Ph.D) - Swinburne University of Technology, Faculty of Information & Communication Technologies, 2009.
A dissertation presented in fulfillment of the requirements for the degree of Doctor of Philosophy, [Faculty of Information and Communication Technologies], Swinburne University of Technology, 2009. Typescript. Bibliography p. 215-236.
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Shiomi, Tadashi. "Differential Very-Long-Baseline Interferometry Techniques for Precise Orbit Determination of a Geosynchronous Satellite." Kyoto University, 1986. http://hdl.handle.net/2433/162201.

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McAlpine, Kim. "A VLBI study of OH masers in a proto-planetary nebula OH 0.9+1.3." Thesis, Rhodes University, 2008. http://hdl.handle.net/10962/d1005285.

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This thesis reports the calibration, imaging and analysis of one epoch of VLBA observations of the 1612 MHz OH maser emission from the protoplanetary nebula OH 0.9+1.3. These are the first polarisation VLBI observations of this source and the spatial morphology of the OH emission is resolved on this scale. Proto-planetary nebulae represent the transition phase in the evolution of stars between the asymptotic giant branch (AGB) phase and their emergence as planetary nebulae. A long-standing astronomical question is how the predominantly spherical circumstellar envelopes of AGB stars evolve into the bipolar and axisymmetric structures that are commonly observed in planetary nebula. Proto-planetary nebulae offer a unique opportunity to study this transformation process. The high-resolution VLBI maps produced in this thesis were used to investigate the morphology and kinematics of OH 0.9+1.3 with a view to gaining insight into the development of asymmetries in the circumstellar material. The OH maser emission of OH 0.9+1.3 has a double-peaked profile with one peak blue-shifted and the other red-shifted with respect to the stellar velocity. The total intensity maser maps demonstrate a considerable degree of asymmetry with the blue- and red-shifted emission located in spatially distinct regions of the envelope. The blue-shifted emission is distributed preferentially along an axis at a projected position angle of » 135± ( North through East). The morphology of this source is not consistent with the standard symmetric thin-shell model and an attempt to fit the traditional OH/IR kinematic model of a simple expanding shell to the maser components was found to be unsatisfactory. No definitive evidence of a bipolar outflow was observed either. The high degree of asymmetry observed in the source is consistent with its status as a proto-planetary nebula. The source was imaged in all four Stokes parameters and the fractional linear and circular polarisations of the maser components were derived from the Stokes parameter maps. In all except one of the components the total fractional polarisation was found to be low ( < 15%). The mean fractional linear and circular polarisation were calculated to be 5.54% and 7.11% respectively. The absence of an identifiable Zeeman pair in the Stokes V map prohibited the estimation of the magnetic field in the circumstellar envelope of this source.
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Books on the topic "Very long baseline interferometry"

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Felli, Marcello, and Ralph E. Spencer, eds. Very Long Baseline Interferometry. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-2428-4.

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Marcello, Felli, Spencer Ralph E, and North Atlantic Treaty Organization. Scientific Affairs Division., eds. Very long baseline interferometry techniques and applications. Dordrecht: Kluwer Academic Publishers, 1989.

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Beyer, Winfried. Laufzeitschätzung in digitalen Korrelationsinterferometern unter besonderer Betrachtung des MK II-Systems des Max-Planck-Instituts für Radioastronomie. Bonn: [Geodätisches Institut der Universität Bonn], 1985.

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D, Romney Jonathan, and Reid Mark Jonathan 1948-, eds. Future directions in high resolution astronomy: The 10th anniversary of the VLBA : proceedings of a meeting held in Socorro, New Mexico, USA, 8-12 June 2003. San Francisco, Calif: Astronomical Society of the Pacific, 2005.

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1963-, Lawson Peter R., ed. Selected papers on long baseline stellar interferometry. Bellingham, Wash., USA: SPIE Optical Engineering Press, 1997.

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Brouwer, Frits J. J. On the principles, assumptions and methods of geodetic very long baseline interferometry. Delft, The Netherlands: Rijkscommissie voor Geodesie, 1985.

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Lowe, Stephen T. Theory of post-block 2 VLBI observable extraction. Pasadena, Calif: National Aeronautics and Space Administration, Jet Propulsion Laboratory, California Institute of Technology, 1992.

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Lowe, Stephen T. Theory of post-block 2 VLBI observable extraction. Pasadena, Calif: National Aeronautics and Space Administration, Jet Propulsion Laboratory, California Institute of Technology, 1992.

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Lowe, Stephen T. Theory of post-block 2 VLBI observable extraction. Pasadena, Calif: National Aeronautics and Space Administration, Jet Propulsion Laboratory, California Institute of Technology, 1992.

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Anton, Zensus J., Diamond P. J, and Napier P. J, eds. Very long baseline interferometry and the VLBA: Proceedings of a summer school held in Socorro, New Mexico, June 23-30, 1993. San Francisco, Calif: Astronomical Society of the Pacific, 1995.

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Book chapters on the topic "Very long baseline interferometry"

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Spencer, R. E. "Fundamentals of Interferometry." In Very Long Baseline Interferometry, 11–25. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-2428-4_2.

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Thompson, A. Richard, James M. Moran, and George W. Swenson. "Very-Long-Baseline Interferometry." In Astronomy and Astrophysics Library, 391–483. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-44431-4_9.

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Wiesemeyer, Helmut, and Axel Nothnagel. "Very Long Baseline Interferometry." In Encyclopedia of Solid Earth Geophysics, 1–7. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-10475-7_99-1.

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Moran, J. M. "Very Long Baseline Interferometry." In Highlights of Astronomy, 553–54. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-0977-9_84.

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Wiesemeyer, Helmut, and Axel Nothnagel. "Very Long Baseline Interferometry." In Encyclopedia of Solid Earth Geophysics, 1509–15. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-90-481-8702-7_99.

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Nothnagel, Axel. "Very Long Baseline Interferometry." In Handbuch der Geodäsie, 1–58. Berlin, Heidelberg: Springer Berlin Heidelberg, 2018. http://dx.doi.org/10.1007/978-3-662-46900-2_110-1.

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Nothnagel, Axel. "Very Long Baseline Interferometry." In Mathematische Geodäsie/Mathematical Geodesy, 1257–314. Berlin, Heidelberg: Springer Berlin Heidelberg, 2020. http://dx.doi.org/10.1007/978-3-662-55854-6_110.

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Wiesemeyer, Helmut, and Axel Nothnagel. "Very Long Baseline Interferometry." In Encyclopedia of Solid Earth Geophysics, 1902–7. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-58631-7_99.

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Cotton, W. D. "Very Long Baseline Interferometry." In High Angular Resolution in Astrophysics, 165–91. Dordrecht: Springer Netherlands, 1997. http://dx.doi.org/10.1007/978-94-009-0041-7_9.

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Anderson, B. "Basic Radio Astronomy." In Very Long Baseline Interferometry, 3–10. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-2428-4_1.

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Conference papers on the topic "Very long baseline interferometry"

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Paragi, Zsolt, Leith Godfrey, Cormac Reynolds, Maria J. Rioja, Adam Deller, Bo Zhang, Leonid Gurvits, et al. "Very Long Baseline Interferometry with the SKA." In Advancing Astrophysics with the Square Kilometre Array. Trieste, Italy: Sissa Medialab, 2015. http://dx.doi.org/10.22323/1.215.0143.

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An, Tao, Baoqiang Lao, Junyi Wang, Yang Lu, Yanheng Wei, and Xiaocong Wu. "Space millimeter-wavelength very long baseline interferometry simulation software." In 2016 8th IEEE International Conference on Communication Software and Networks (ICCSN). IEEE, 2016. http://dx.doi.org/10.1109/iccsn.2016.7586664.

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Casey, Simon, Richard Hughes-Jones, Stephen Kershaw, Ralph Spencer, and Matt Strong. "Real Time Data Transfer for Very Long Baseline Interferometry." In 2007 15th IEEE-NPSS Real-Time Conference. IEEE, 2007. http://dx.doi.org/10.1109/rtc.2007.4382826.

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Kiuchi, Hitoshi, Yukio Takahashi, Akihiro Kaneko, Jun Amagai, Taizoh Yoshino, Noriyuki Kawaguchi, Hideyuki Kobayashi, et al. "Very long baseline connected interferometry via the ATM network." In Astronomical Telescopes and Instrumentation, edited by Robert I. Kibrick and Anders Wallander. SPIE, 2000. http://dx.doi.org/10.1117/12.387226.

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Van Langevelde, Huib, Richard Schilizzi, Arnold van Ardenne, Lout Sondaar, and Albert-Jan Boonstra. "Very Long Baseline Interferometry: the EVN, WSRT, and JIVE." In Westerbork Telescope 50th Anniversary. Trieste, Italy: Sissa Medialab, 2019. http://dx.doi.org/10.22323/1.361.0008.

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Clivati, Cecilia, Roberto Aiello, Giuseppe Bianco, Claudio Bortolotti, Valentina Di Sarno, Pasquale Maddaloni, Filippo Levi, et al. "A Coherent Optical Fiber Link for Very Long Baseline Interferometry." In CLEO: Science and Innovations. Washington, D.C.: OSA, 2020. http://dx.doi.org/10.1364/cleo_si.2020.sm2n.4.

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Holdaway, Mark A., and J. F. C. Wardle. "Maximum entropy imaging of polarization in very long baseline interferometry." In San Diego '90, 8-13 July, edited by Arthur F. Gmitro, Paul S. Idell, and Ivan J. LaHaie. SPIE, 1990. http://dx.doi.org/10.1117/12.23679.

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Urekar, Marjan, Nemanja Gazivoda, and Jelena Dordevic-Kozarov. "Stochastic Flash ADC in Hardware Correlator for Very Long Baseline Interferometry." In 2018 5th IEEE International Workshop on Metrology for AeroSpace (MetroAeroSpace). IEEE, 2018. http://dx.doi.org/10.1109/metroaerospace.2018.8453574.

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Chen, L., J. T. Lai, Z. J. Xu, Y. J. Zhang, and M. S. Tong. "Design of a data playback module for Very Long Baseline Interferometry." In 2016 Progress in Electromagnetic Research Symposium (PIERS). IEEE, 2016. http://dx.doi.org/10.1109/piers.2016.7735628.

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Fung, Andy, Lorene Samoska, James Bowen, Steven Montanez, Jacob Kooi, Melissa Soriano, Christopher Jacobs, et al. "X- to Ka- Band Cryogenic LNA Module for Very Long Baseline Interferometry." In 2020 IEEE/MTT-S International Microwave Symposium (IMS). IEEE, 2020. http://dx.doi.org/10.1109/ims30576.2020.9224106.

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Reports on the topic "Very long baseline interferometry"

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KAHN, S. A. BNL VERY LONG BASELINE EXPERIMENT WITH A SUPER NEUTRINO BEAM. Office of Scientific and Technical Information (OSTI), November 2003. http://dx.doi.org/10.2172/15006715.

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BISHAI, M., J. HEIM, C. LEWIS, A. D. MARINO, B. VIREN, and F. YUMICEVA. SIMULATION OF A WIDE-BAND LOW-ENERGY NEUTRINO BEAM FOR VERY LONG BASELINE NEUTRINO OSCILLATION EXPERIMENTS. Office of Scientific and Technical Information (OSTI), August 2006. http://dx.doi.org/10.2172/891295.

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DIWAN, M., W. MARCIANO, W. WENG, D. BEAVIS, M. BRENNAN, M. C. CHEN, R. FERNOW, and ET AL. VERY LONG BASELINE NEUTRINO OSCILLATION EXPERIMENTS FOR PRECISE MEASURMENTS OF OSCILLATION PARAMETERS AND SEARCH FOR N MU YIELDS N EPSILON. Office of Scientific and Technical Information (OSTI), October 2002. http://dx.doi.org/10.2172/805485.

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Wilson, D., Vladimir Ostashev, Michael Shaw, Michael Muhlestein, John Weatherly, Michelle Swearingen, and Sarah McComas. Infrasound propagation in the Arctic. Engineer Research and Development Center (U.S.), December 2021. http://dx.doi.org/10.21079/11681/42683.

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This report summarizes results of the basic research project “Infrasound Propagation in the Arctic.” The scientific objective of this project was to provide a baseline understanding of the characteristic horizontal propagation distances, frequency dependencies, and conditions leading to enhanced propagation of infrasound in the Arctic region. The approach emphasized theory and numerical modeling as an initial step toward improving understanding of the basic phenomenology, and thus lay the foundation for productive experiments in the future. The modeling approach combined mesoscale numerical weather forecasts from the Polar Weather Research and Forecasting model with advanced acoustic propagation calculations. The project produced significant advances with regard to parabolic equation modeling of sound propagation in a windy atmosphere. For the polar low, interesting interactions with the stratosphere were found, which could possibly be used to provide early warning of strong stratospheric warming events (i.e., the polar vortex). The katabatic wind resulted in a very strong low-level duct, which, when combined with a highly reflective icy ground surface, leads to efficient long-distance propagation. This information is useful in devising strategies for positioning sensors to monitor environmental phenomena and human activities.
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Cannon, Mariah, and Pauline Oosterhoff. Bonded: Life Stories from Agricultural Communities in South-Eastern Nepal. Institute of Development Studies (IDS), June 2021. http://dx.doi.org/10.19088/clarissa.2021.003.

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In the Terai region of South-Eastern Nepal, there persists a form of agricultural bonded labour called Harwa-Charwa, rooted in agricultural feudal social relations. The Terai has a long and dynamic political history with limited employment opportunities and high levels of migration. This paper is an external qualitative analysis of over 150 life stories from individuals living in an area with high levels of bonded labour. These stories were previously analysed during a workshop through a collective participatory analysis. Both the participatory analysis and external analysis found similar mechanisms that trap people in poverty and bonded labour. The disaggregation by age in the external analysis could explain why child marriage and child labour were very important in the collective analysis but did not match the results of a baseline survey in the same geographical area that found only a few cases. The respondents were aged between 15 and 65. Child marriage and child labour had shaped the lives of the adults but have since decreased. Methodologically, the different ways of analysis diverge in their ability to differentiate timelines. The participatory analysis gives historical insights on pathways into child labour, but although some of the social norms persist this situation has changed.
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Eickhout, Bas, Hans van Meijl, Andrzej Tabeau, and Elke Stehfest. The Impact of Environmental and Climate Constraints on Global Food Supply. GTAP Working Paper, April 2008. http://dx.doi.org/10.21642/gtap.wp47.

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*Chapter 9 of the forthcoming book "Economic Analysis of Land Use in Global Climate Change Policy," edited by Thomas W. Hertel, Steven Rose, and Richard S.J. Tol The goal of this Chapter is to study the complex interaction between agriculture, economic growth and the environment, given future uncertainties. We combine economic concepts and biophysical constraints in one consistent modeling framework to be able to quantify and analyze the long-term socio-economic and environmental consequences of different scenarios. Here, we present the innovative methodology of coupling an economic and a biophysical model to combine state of the art knowledge from economic and biophysical sources. First, a comprehensive representation of the agricultural and land markets is required in the economic model. Therefore we included a land demand structure to reflect the degree of substitutability of types of land-use types and we included a land supply curve to include the process of land conversion and land abandonment. Secondly, the adapted economic model (LEITAP) is linked to the biophysical-based integrated assessment model IMAGE allowing to feed back spatially and temporarily varying land productivity to the economic framework. Thirdly, the land supply curves in the economic model are parameterized by using the heterogeneous information of land productivity from IMAGE. This link between an economic and biophysical model benefits from the strengths of both models. The economic model captures features of the global food market, including relations between world regions, whereas the bio-physical model adds geographical explicit information on crop growth within each world region. An illustrative baseline analyses shows the environmental consequences of the default baseline and a sensitivity analyses is performed with regard to the land supply curve. Results indicate that economic and environmental consequences are very dependent on whether a country is land scarce or land abundant.
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Boyle, M. Terrestrial vegetation monitoring at Ocmulgee Mounds National Historical Park: 2021 data summary. National Park Service, July 2023. http://dx.doi.org/10.36967/2299748.

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The Southeast Coast Network (SECN) conducts long-term terrestrial vegetation monitoring as part of the NPS Inventory and Monitoring Program. The vegetation community vital sign is one of the primary-tier resources identified by SECN park managers, and monitoring is conducted at 15 network parks (DeVivo et al. 2008). Monitoring plants and their associated communities over time allows for targeted understanding of ecosystems within the SECN geography, which provides managers information about the degree of change within their parks’ natural vegetation. 2021 marks the first year of conducting this monitoring effort at Ocmulgee Mounds National Historical Park (OCMU). Eight vegetation plots were established throughout the park in early May. Data collected in each plot included species richness across multiple spatial scales, species-specific cover and constancy, species-specific woody stem seedling/sapling counts and adult tree (greater than 10 centimeters [3.9 inches {in}]) diameter at breast height (DBH), overall tree health, landform, soil, observed disturbance, and woody biomass (i.e., fuel load) estimates. This report summarizes the baseline (year 1) terrestrial vegetation data collected at Ocmulgee Mounds National Historical Park in 2021. Data were stratified across two dominant broadly defined habitats within the park, Coastal Plain Alluvial Wetlands and Coastal Plain Upland Forests. Noteworthy findings include: 142 vascular plant taxa (species or lower) were observed across eight vegetation plots, including 15 species not previously documented within the park. The most frequently encountered species in each broadly defined habitat included: Coastal Plain Alluvial Wetlands: Chinese privet (Ligustrum sinense), Chinese tallow (Triadica sebifera), Japanese honeysuckle (Lonicera japonica), eastern poison ivy (Toxicodendron radicans var. radicans), and smallspike false nettle (Boehmeria cylindrica). Coastal Plain Upland Forests: sweetgum (Liquidambar styraciflua), muscadine (Muscadinia rotundifolia var. rotundifolia), winged elm (Ulmus alata), water oak (Quercus nigra), loblolly pine (Pinus taeda), yaupon (Ilex vomitoria), Japanese honeysuckle, American beautyberry (Callicarpa americana), ebony spleenwort (Asplenium platyneuron), and multiple species of woody vines. Eleven non-native species invasive (Category 1 or Category 2) by the Georgia Exotic Pest Plant Council (GA-EPPC 2023) were encountered within the park during this monitoring effort. Three of these species—Chinese privet, Chinese tallow, and Japanese honeysuckle—were among the most frequent and abundant of all species observed within Coastal Plain Alluvial Wetland plots. There were no observations of vascular plant species listed as rare and tracked by the Georgia Department of Natural Resources (GADNR 2023) within these monitoring plots. Sweetgum, red maple (Acer rubrum), swamp tupelo (Nyssa biflora), and Chinese tallow were the most dominant species within the tree stratum of Coastal Plain Alluvial Wetland sites; water oak, loblolly pine, and sweetgum were the most dominant species of Coastal Plain Upland Forests. There were very few observable disturbances to natural and semi-natural vegetation communities documented during this monitoring effort, including very little to no impact of browsing by white-tailed deer, rooting by feral hogs, or presence of diseased or dying trees. The two most pronounced threats to native vegetation on the park are (1) the high prevalence of non-native, invasive plant species (particular within alluvial habitat, and (2) the altered hydrology of the park’s alluvial wetlands from conversion of large berms for vehicle and railroad traffic. Long-term monitoring data will aid in understanding how these threats over time impact the park’s forest communities.
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Zimmerman, Ephraim, and Staphanie Perles. Vegetation monitoring in relation to white-tailed deer browsing in First State National Historical Park: 2021 summary report. National Park Service, July 2023. http://dx.doi.org/10.36967/2299655.

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Baseline information on canopy regeneration and plant community composition is needed in order to better understand white-tailed deer browsing impacts at First State National Historical Park (FRST). In 2021, the Pennsylvania Natural Heritage Program (PNHP) established 20 permanent vegetation monitoring plots following methods developed by the NPS Eastern Rivers and Mountains Network (ERMN) to assess and monitor trends in vegetation (Perles et al. 2014b; Perles et al. 2017). These protocols provided an efficient method of assessing the current status of native and non-native vegetation and deer browsing impact. This report documents the methodology used to quantify the vegetative composition of natural areas at FRST and provides a summary of the data collected in the first year of monitoring. This first year’s activities (2021) included the initial baseline vegetation assessment and summary of results from the baseline data analysis. A variety of metrics used to assess the impact of deer browsing on the vegetation were calculated and are presented. A second survey is proposed for 2024. PNHP used the NPS ERMN database and analysis methods (Perles et al. 2014b) to summarize the condition in year 1 (2021). In year 4 (2024), PNHP will investigate changes in the condition of browse-sensitive understory plants and tree seedlings. Plots occurred in a variety of settings, ranging from younger successional communities to more mature forest stands. Seventy-five percent (75%) of the plots occurred in Mature or Late Successional forests. Disturbances and stressors, such as deer browsing can strongly influence future forest structure as open woodlands mature. A large population of white-tailed deer may severely impact succession from the open woodlands towards closed canopy forest. In closed canopy, later successional forests, a large deer population may inhibit canopy tree recruitment leading to regeneration failure. Given that FRST managers desire to maintain the landscape as forest, it is important to maintain an adequate number of seedlings and saplings of tree species to ensure the persistence of canopy of native tree species as Mature and Late Successional Forests continue to age. The 20 permanent sampling plots occurred within 5 plant communities described by Ebert (2016) and were classified using agglomerative hierarchical clustering (HAC analysis) and indicator species analysis. The most common plant communities within the group of sampling plots were the Mixed oak – beech forest and Mesic mixed tulip – oak-hickory-beech forest. The remaining plots were found in successional Tuliptree woodland, Successional woodland, and Thicket types. All plots were assigned to these types described in Ebert (2016) and crosswalked to the National Vegetation Classification (USNVC). A total of 128 plant species were recorded from the 20 plots at FRST. Eighteen (18) species were found in over ½ of the plots surveyed, of which eight (8) were non-native. In all, 29 plants occurring in the plots (23% of total species richness) were considered introduced (non-native). Non-native plant cover ranged from 0–98% as measured in the monitoring plot quadrats. Indicators of deer browsing varied by plant community type at FRST. In general, the drier Mixed oak – beech forests showed substantially greater impact of deer browsing and fewer seedlings of canopy species in the understory. FRST monitoring protocols focus on a few plant species considered as preferred food for white-tailed deer. Sustained browsing may be affecting long-term viability of these species within the parks. Based on the status of these regeneration metrics in FRST, we suggest that the forest in FRST are in imminent regeneration failure. We define imminent failure as parks that are experiencing severe regeneration failure and are at risk of forest loss due to very low seedling and sapling abundance, as well as species mismatches between canopy and regeneration layers. Given the poor regeneration of canopy species across all community types at FRST, managers should seek opportunities to conduct adaptive management in the park’s forests, especially mixed oak – beech forest, to experiment with and monitor the effects of fire, browse exclosures, and canopy thinning to encourage native canopy tree regeneration.
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Bingham, Sonia, Craig Young, and Tanni Hubbard. Sentinel wetlands in Cuyahoga Valley National Park: II. Condition trends for wetlands of management concern, 2008?2018. National Park Service, 2023. http://dx.doi.org/10.36967/2301705.

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Twenty important management areas (wetlands of management concern) and reference wetlands compose the sentinel wetlands at Cuyahoga Valley National Park. These wetlands are monitored more intensively than other wetlands in the program. This is the second report in a two-part series, designed to summarize the results from intensive vegetation surveys completed at sentinel wetlands from 2008 to 2018. The first report (Bingham and Young 2023) characterized the conditions in each wetland and provided baseline reference information for other reports and site-specific projects. In this report, we examine results from five selected metrics more closely within and across three natural wetlands of management concern groups (restoration wetlands, mitigation wetlands, and rare habitat wetlands) using the reference wetlands as overall benchmarks. We used the Ohio Rapid Assessment Method (ORAM) to evaluate habitat in the sentinel wetlands. In addition, a total of 37 long-term sample plots were established within these wetlands to monitor biological conditions over time using vegetation as an indicator. Multiple plots were located in larger wetland complexes to capture spatial differences in condition. Vegetation was intensively surveyed within the plots using the Vegetation Index of Biotic Integrity (VIBI), where all plant species are identified to the lowest taxonomic level possible (genus or species). The sample plots were surveyed twice, and the five evaluation metrics included the VIBI score, Floristic Quality Assessment Index (FQAI), percent sensitive plant species, percent invasive graminoids, and species richness. For the analysis, VIBI plot locations were rank ordered based on their 2018 scores, the range and average for each metric was examined across the wetlands of management concern groups and plotted against reference wetlands for comparison, and the two survey years (pre-2015 and 2018) were plotted against each other for substantial changes from the established baseline. Across the sample plot locations, VIBI scores ranged from a low of 7 (Stanford Run SF1) to a high of 91 (Columbia Run 554). The top scoring plots were at four reference wetlands (Stumpy Basin 526, Virginia Kendall Lake 241K, Columbia Run 554, and Boston Mills 683) and one rare habitat wetland (Beaver Marsh BM3). All of these plots fell within an excellent condition range in one or both survey years. They each have unique habitats with some specialized plant species. The majority (24) of the sentinel wetlands plots ranked within the poor or fair ranges. These include the three mitigation wetlands: Brookside 968, Rockside RS2, and Krejci, as well as all plots within the Pleasant Valley and Stanford Run wetlands. Most of the large wetlands had dramatic condition differences within their boundaries? effected by pollution sources, land-use modifications, and/or invasive species in some areas more than others. We documented these wide condition ranges at Fawn Pond, Virginia Kendall Lake, Beaver Marsh and Stumpy Basin, but the most pronounced within-wetland differences were at Virginia Kendall Lake, which had a 58-point difference between the highest and lowest scoring plot. Fawn Pond is in good condition at most plots and scored very high in comparison to other wetlands within the riverine mainstem hydrogeomorphic class. The average and range of most metric scores were notably different across the four different wetlands groups. Average values at rare habitat wetlands plots were similar to reference plots for VIBI and FQAI scores, percent invasive graminoids, and percent sensitive metrics. Krejci KR1 and Fawn Pond FP3 had unusually high percent cover of sensitive species (31.0% and 27.9%, respectively) for the mitigation and restoration groupings. However, average overall metric scores across the restoration and mitigation wetlands were generally very low, with Stanford Run being the lowest scoring restoration wetland and Brookside being the lowest scoring mitigation wetland. With restoration efforts completed, the expectation is that mitigation wetlands should be performing much higher. Two of the three mitigation wetlands sites are not meeting the mitigation benchmarks that were created for them by the US Army Corp of Engineers and the Ohio Environmental Protection Agency. Contractor reports state that the wetlands met the criteria within the first five years of establishment. However, upon release from monitoring and maintenance, invasive species have gradually re-established, which has led to condition deterioration over time, and lower metric scores. VIBI scores stayed the same or improved (only slightly in many cases) in the majority of plots (67.6%) between survey years. The Krecji mitigation wetlands had the largest improvement in VIBI scoring. Scores at six plots decreased by at least 10 points from the baseline survey. Two of the park?s most beloved wetlands, Beaver Marsh (at one location) and the Stumpy Basin reference plot, had the two most notable declines in VIBI scores. In 2018, 11 plots (29.7%) had greater than 25% invasive graminoid cover (e.g. cattail, common reed grass, reed canary grass) and 18 plots (48.7%) experienced an increase in invasive graminoid cover between survey years. A marked increase (>10% cover) in invasive graminoids was documented at eight locations (Rockside 1079RS2, Beaver Marsh BM5, Fawn Pond FP3 and FP4, Brookside 968, Stumpy Basin SB1, and two other Pleasant Valley plots: 1049 and 969). These trends are likely to continue, and biological conditions are expected to deteriorate at these wetlands in response. Regardless of invasive species increases, many of the wetlands showed remarkable resilience over the last decade with fairly stable VIBI categories.
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India: Enhancing girls' life skills requires long-term commitment. Population Council, 2005. http://dx.doi.org/10.31899/rh16.1003.

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While adolescents in India face a rapidly changing economic environment, the choices available to unmarried girls are very different from those available to boys. Girls are much less likely than boys to remain unmarried into their twenties, complete middle school, or generate income. Due to social norms, they have limited control over their life choices, and are less likely than boys to be allowed mobility within or beyond their immediate community. In 2001, the Population Council teamed with CARE India to test a pilot intervention to enhance skills and expand life choices for adolescent girls living in the slums of Allahabad. The 10-month intervention tested the effect of the skills intervention on the girls’ reproductive health knowledge, social contacts and mobility, self-esteem, and perception of gender roles. The impacts were assessed using survey responses from girls who were interviewed in both baseline and endline surveys. As noted in this brief, girls and their parents found the life skills training acceptable, but the intervention had little overall impact.
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