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Monitoring vegetation phenology using an infrared-enabled security camera
Sensor-based monitoring of vegetation phenology is being widely used to quantify phenological responses to climate variability and change. Digital repeat photography, in particular, can characterize the seasonality of canopy greenness. However, these data cannot be directly compared to satellite vegetation indices (e.g. NDVI, the normalized difference vegetation index) that require information about vegetation properties at near-infrared (NIR) wavelengths. Here, we develop a new method, using an inexpensive, NIR-enabled camera originally designed for security monitoring, to calculate a ācamera NDVIā from sequential visible and visible + NIR photographs. We use a lab experiment for proof-of-concept, and then test the method using a year of data from an ongoing field campaign in a mixed temperate forest. Our analysis shows that the seasonal cycle of camera NDVI is almost identical to that of NDVI measured using narrow-band radiometric instruments, or as observed from space by the MODIS platform. This camera NDVI thus provides different information about the state of the canopy than can be obtained using only visible-wavelength imagery. In addition to phenological monitoring, our method should be useful for a variety of applications, including continuous monitoring of plant stress and quantifying vegetation responses to manipulative treatments in large field experiments.Organismic and Evolutionary Biolog
Gamma-ray counterparts of 2WHSP high-synchrotron-peaked BL Lac objects as possible signatures of ultra-high-energy cosmic-ray emission
We present a search for high-energy -ray emission from 566 Active
Galactic Nuclei at redshift , from the 2WHSP catalog of
high-synchrotron peaked BL Lac objects with eight years of Fermi-LAT data. We
focus on a redshift range where electromagnetic cascade emission induced by
ultra-high-energy cosmic rays can be distinguished from leptonic emission based
on the spectral properties of the sources. Our analysis leads to the detection
of 160 sources above (TS ) in the 1 - 300 GeV
energy range. By discriminating significant sources based on their -ray
fluxes, variability properties, and photon index in the Fermi-LAT energy range,
and modeling the expected hadronic signal in the TeV regime, we select a list
of promising sources as potential candidate ultra-high-energy cosmic-ray
emitters for follow-up observations by Imaging Atmospheric Cherenkov
Telescopes.Comment: 15 pages, 9 figures, 2 tables, submitted to MNRA
Skeletal and Dental Health of Precontact Marquesans: The Bioarchaeology of the Human Skeletons from Haāatuatua, Nuku Hiva, Marquesas Islands
Skeletal and dental indicators (e.g., stature, linear enamel hypoplasia, cribra orbitalia, trauma, dental pathologies, and other evidence of disease) recorded in 45 subadult and 36 adult skeletons from the NHaa 1 site at Haāatuatua, Nuku Hiva, northern Marquesas, are used to examine the health, diet, and lifestyle of precontact Marquesans during the Expansion Period (ca. A.D. 1300ā1600). Limited comparisons with skeletons from Hane on Ua Huka and other Pacific Island series augment this study. In addition to elevated numbers of subadult deaths, many during the first year of life, significant palaeopathology suggestive of infection, anemia, or metabolic disease was noted for seven subadults. In contrast, very little palaeopathology was noted in the adults and no significant sex differences for most indicators of health. With few exceptions, the skeletal and dental indicators of health in the Haāatuatua and Hane series were very similar. Compared to
other precontact Pacific series, the Haāatuatua males were tall and similar to other East
Polynesians. Higher frequencies of stress fracture in the lower back at Haāatuatua may be
linked to activities associated with landscape changes and the construction of stone megalithic structures. The skeletal and dental indicators of health observed in the Haāatuatua burials are most like those reported for other East Polynesian series. The precontact inhabitants of the Marquesas were generally healthy, contrary to expectations of increased disease frequencies and evidence of warfare during the Expansion Period at Haāatuatua. These new bioarchaeological data broaden our understanding of the health and lifestyle of precontact Polynesians
Reply to: Terry, J. and Goff, J. comment on āLate Cenozoic sea level and the rise of modern rimmed atollsā by Toomey et al. (2016), Palaeogeography, Palaeoclimatology, Palaeoecology 451: 73ā83
This paper is not subject to U.S. copyright. The definitive version was published in Palaeogeography, Palaeoclimatology, Palaeoecology 469 (2017): 159-160, doi:10.1016/j.palaeo.2016.11.028
Observing Strategies for the NICI Campaign to Directly Image Extrasolar Planets
We discuss observing strategy for the Near Infrared Coronagraphic Imager
(NICI) on the 8-m Gemini South telescope. NICI combines a number of techniques
to attenuate starlight and suppress superspeckles: 1) coronagraphic imaging, 2)
dual channel imaging for Spectral Differential Imaging (SDI) and 3) operation
in a fixed Cassegrain rotator mode for Angular Differential Imaging (ADI). NICI
will be used both in service mode and for a dedicated 50 night planet search
campaign. While all of these techniques have been used individually in large
planet-finding surveys, this is the first time ADI and SDI will be used with a
coronagraph in a large survey. Thus, novel observing strategies are necessary
to conduct a viable planet search campaign.Comment: 12 pages, 10 figures, submitted to Proceedings of the SPI
Late Cenozoic sea level and the rise of modern rimmed atolls
This paper is not subject to U.S. copyright. The definitive version was published in Palaeogeography, Palaeoclimatology, Palaeoecology 451 (2016): 73-83, doi:10.1016/j.palaeo.2016.03.018.Sea-level records from atolls, potentially spanning the Cenozoic, have been largely overlooked, in part because the processes that control atoll form (reef accretion, carbonate dissolution, sediment transport, vertical motion) are complex and, for many islands, unconstrained on million-year timescales. Here we combine existing observations of atoll morphology and corelog stratigraphy from Enewetak Atoll with a numerical model to (1) constrain the relative rates of subsidence, dissolution and sedimentation that have shaped modern Pacific atolls and (2) construct a record of sea level over the past 8.5 million years. Both the stratigraphy from Enewetak Atoll (constrained by a subsidence rate of ~ 20 m/Myr) and our numerical modeling results suggest that low sea levels (50ā125 m below present), and presumably bi-polar glaciations, occurred throughout much of the late Miocene, preceding the warmer climate of the Pliocene, when sea level was higher than present. Carbonate dissolution through the subsequent sea-level fall that accompanied the onset of large glacial cycles in the late Pliocene, along with rapid highstand constructional reef growth, likely drove development of the rimmed atoll morphology we see today.Support for this work was provided through a Jackson School Distinguished Postdoctoral Fellowship to Michael Toomey
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