3,367 research outputs found
Wolf spiders of the Pacific region: the genus \u3ci\u3eZoica\u3c/i\u3e (Araneae, Lycosidae)
The wolf spider genus Zoica Simon 1898 is currently known only from the Indo-Australasian region, including India in the west to northern Western Australia and Papua New Guinea in the east. Here we extend the known distribution of the genus into the Pacific region by describing two new species, Z. carolinensis new species from the Caroline Islands, Federated States of Micronesia, and Z. pacifica new species from the Republic of the Marshall Islands
Contributors to the March Issue/Notes
Notes by John A. Berry, Joseph P. Judge, Paul Kempter, Joseph A. McCabe, William T. Kirby, Granville P. Ziegler, and Donald F. Wise
New Methods for Measurements of Photosynthesis from Space
Our ability to close the Earth's carbon budget and predict feedbacks in a warming climate
depends critically on knowing where, when, and how carbon dioxide (CO2) is exchanged
between the land and atmosphere. In particular, determining the rate of carbon fixation by
the Earth's biosphere (commonly referred to as gross primary productivity, or GPP) and the
dependence of this productivity on climate is a central goal. Historically, GPP has been
inferred from spectral imagery of the land and ocean. Assessment of GPP from the color of
the land and ocean requires, however, additional knowledge of the types of plants in the
scene, their regulatory mechanisms, and climate variables such as soil moistureâjust the
independent variables of interest!
Sunlight absorbed by chlorophyll in photosynthetic organisms is mostly used to drive
photosynthesis, but some can also be dissipated as heat or reâradiated at longer wavelengths
(660â800 nm). This nearâinfrared light reâemitted from illuminated plants is termed solarinduced
fluorescence (SIF), and it has been found to strongly correlate with GPP. To advance
our understanding of SIF and its relation to GPP and environmental stress at the planetary
scale, the Keck Institute for Space Studies (KISS) convened a workshopâheld in Pasadena,
California, in August 2012âto focus on a newly developed capacity to monitor chlorophyll
fluorescence from terrestrial vegetation by satellite. This revolutionary approach for
retrieving global observations of SIF promises to provide direct and spatially resolved
information on GPP, an ideal bottomâup complement to the atmospheric net CO2 exchange
inversions.
Workshop participants leveraged our efforts on previous studies and workshops related to
the European Space Agencyâs FLuorescence EXplorer (FLEX) mission concept, which had
already targeted SIF for a possible satellite mission and had developed a vibrant research
community with many important publications. These studies, mostly focused on landscape,
canopy, and leafâlevel interpretation, provided the groundâwork for the workshop, which
focused on the global carbon cycle and synergies with atmospheric net flux inversions.
Workshop participants included key members of several communities: plant physiologists
with experience using active fluorescence methods to quantify photosynthesis; ecologists
and radiative transfer experts who are studying the challenge of scaling from the leaf to
regional scales; atmospheric scientists with experience retrieving photometric information
from spaceâborne spectrometers; and carbon cycle experts who are integrating new
observations into models that describe the exchange of carbon between the atmosphere,
land and ocean. Together, the participants examined the link between âpassiveâ fluorescence
observed from orbiting spacecraft and the underlying photochemistry, plant physiology and
biogeochemistry of the land and ocean.
This report details the opportunity for forging a deep connection between scientists doing
basic research in photosynthetic mechanisms and the more applied community doing
research on the Earth System. Too often these connections have gotten lost in empiricism
associated with the coarse scale of global models. Chlorophyll fluorescence has been a major
tool for basic research in photosynthesis for nearly a century. SIF observations from space,
although sensing a large footprint, probe molecular events occurring in the leaves below.
This offers an opportunity for direct mechanistic insight that is unparalleled for studies of
biology in the Earth System.
A major focus of the workshop was to review the basic mechanisms that underlie this
phenomenon, and to explore modeling tools that have been developed to link the biophysical
and biochemical knowledge of photosynthesis with the observableâin this case, the
radiance of SIFâseen by the satellite. Discussions led to the identification of areas where
knowledge is still lacking. For example, the inability to do controlled illumination
observations from space limits the ability to fully constrain the variables that link
fluorescence and photosynthesis.
Another focus of the workshop explored a âtopâdownâ view of the SIF signal from space.
Early studies clearly identified a strong correlation between the strength of this signal and
our best estimate of the rate of photosynthesis (GPP) over the globe. New studies show that
this observation provides improvements over conventional reflectanceâbased remote
sensing in detecting seasonal and environmental (particularly drought related) modulation
of photosynthesis. Apparently SIF responds much more quickly and with greater dynamic
range than typical greenness indices when GPP is perturbed. However, discussions at the
workshop also identified areas where topâdown analysis seemed to be âout in frontâ of
mechanistic studies. For example, changes in SIF based on changes in canopy light
interception and the light use efficiency of the canopy, both of which occur in response to
drought, are assumed equivalent in the topâdown analysis, but the mechanistic justification
for this is still lacking from the bottomâup side.
Workshop participants considered implications of these mechanistic and empirical insights
for largeâscale models of the carbon cycle and biogeochemistry, and also made progress
toward incorporating SIF as a simulated output in land surface models used in global and
regionalâscale analysis of the carbon cycle. Comparison of remotely sensed SIF with modelsimulated
SIF may open new possibilities for model evaluation and data assimilation,
perhaps leading to better modeling tools for analysis of the other retrieval from GOSAT
satellite, atmospheric CO2 concentration. Participants also identified another application for
SIF: a linkage to the physical climate system arising from the ability to better identify
regional development of plant water stress. Decreases in transpiration over large areas of a
continent are implicated in the development and âlockingâinâ of drought conditions. These
discussions also identified areas where current land surface models need to be improved in
order to enable this research. Specifically, the radiation transport treatments need dramatic
overhauls to correctly simulate SIF.
Finally, workshop participants explored approaches for retrieval of SIF from satellite and
groundâbased sensors. The difficulty of resolving SIF from the overwhelming flux of reflected
sunlight in the spectral region where fluorescence occurs was once a major impediment to
making this measurement. Placement of very high spectral resolution spectrometers on
GOSAT (and other greenhouse gasâsensing satellites) has enabled retrievals based on infilling
of solar Fraunhofer lines, enabling accurate fluorescence measurements even in the
presence of moderately thick clouds. Perhaps the most interesting challenge here is that
there is no readily portable groundâbased instrumentation that even approaches the
capability of GOSAT and other planned greenhouse gas satellites. This strongly limits scientistsâ ability to conduct groundâbased studies to characterize the footprint of the GOSAT
measurement and to conduct studies of radiation transport needed to interpret SIF
measurement.
The workshop results represent a snapshot of the state of knowledge in this area. New
research activities have sprung from the deliberations during the workshop, with
publications to follow. The introduction of this new measurement technology to a wide slice
of the community of Earth System Scientists will help them understand how this new
technology could help solve problems in their research, address concerns about the
interpretation, identify future research needs, and elicit support of the wider community for
research needed to support this observation.
Somewhat analogous to the original discovery that vegetation indices could be derived from
satellite measurements originally intended to detect clouds, the GOSAT observations are a
rare case in which a (fortuitous) global satellite dataset becomes available before the
research community had a consolidated understanding on how (beyond an empirical
correlation) it could be applied to understanding the underlying processes. Vegetation
indices have since changed the way we see the global biosphere, and the workshop
participants envision that fluorescence can perform the next indispensable step by
complementing these measurements with independent estimates that are more indicative of
actual (as opposed to potential) photosynthesis. Apart from the potential FLEX mission, no
dedicated satellite missions are currently planned. OCOâ2 and â3 will provide much more
data than GOSAT, but will still not allow for regional studies due to the lack of mapping
capabilities. Geostationary observations may even prove most useful, as they could track
fluorescence over the course of the day and clearly identify stressârelated downâregulation of
photosynthesis. Retrieval of fluorescence on the global scale should be recognized as a
valuable tool; it can bring the same quantum leap in our understanding of the global carbon
cycle as vegetation indices once did
The pholcid spiders of Micronesia and Polynesia (Araneae, Pholcidae)
Records of pholcid spiders from Micronesia and Polynesia are presented, along with records from Indonesia and parts of Melanesia. Nineteen species representing eleven genera are included. An illustrated key for Pacific pholcids is provided. Two species and one genus are not yet known from Micronesia or Polynesia, but are included in the key because they may occur there. Seven species are widespread synanthropic or anthropophilic species, two species are widespread native species, and nine species are endemics of one or several neighboring islands. Distribution maps include only specimens we have seen, not literature records
Notes
Notes by Richard A. Molique, F. Louis Fautsch, John A. Berry, Joseph A. McCabe, Stephen P. Banas, Robert Devine, John J. Locher, and J. S. Montedonico
Leveraging Low-Energy Structural Thermodynamics in Halide Perovskites
Metal halide perovskites (MHPs) combine extraordinary optoelectronic
properties with chemical and mechanical properties not found in their
semiconductor counterparts. For instance, they exhibit optoelectronic
properties on par with single-crystalline gallium arsenide yet exhibit
near-zero formation energies. The small lattice energy of MHPs means they
undergo a rich diversity of polymorphism near standard conditions similar to
organic materials. MHPs also demonstrate ionic transport as high as
state-of-the-art battery electrodes. The most widespread applications for metal
halide perovskites (e.g. photovoltaics and solid-state lighting) typically view
low formation energies, polymorphism, and high ion transport as a nuisance that
should be eliminated. Here, we put these properties into perspective by
comparing them to other technologically relevant semiconductors in order to
highlight how unique this combination of properties is for semiconductors and
to illustrate ways to leverage these properties in emerging applications
Experimental Implementation of the Quantum Baker's Map
This paper reports on the experimental implementation of the quantum baker's
map via a three bit nuclear magnetic resonance (NMR) quantum information
processor. The experiments tested the sensitivity of the quantum chaotic map to
perturbations. In the first experiment, the map was iterated forward and then
backwards to provide benchmarks for intrinsic errors and decoherence. In the
second set of experiments, the least significant qubit was perturbed in between
the iterations to test the sensitivity of the quantum chaotic map to applied
perturbations. These experiments are used to investigate previous predicted
properties of quantum chaotic dynamics.Comment: submitted to PR
Three dimensional graphics station for computer integrated manufacturing research
Issued as Final report, Project no. E-25-69
Interannual variability of photosynthesis across Africa and its attribution
Africa is thought to be a large source of interannual variability in the global carbon cycle, only vaguely attributed to climate fluctuations. This study uses a biophysical model, Simple Biosphere, to examine in detail what specific factors, physiological (acute stress from low soil water, temperature, or low humidity) and biophysical (low vegetation radiation use), are responsible for spatiotemporal patterns of photosynthesis across the African continent during the period 1982-2003. Acute soil water stress emerges as the primary factor driving interannual variability of photosynthesis for most of Africa. Southern savannas and woodlands are a particular hot spot of interannual variability in photosynthesis, owing to high rainfall variability and photosynthetic potential but intermediate annual rainfall. Surprisingly low interannual variability of photosynthesis in much of the Sudano-Sahelian zone derives from relatively low vegetation cover, pronounced humidity stress, and somewhat lower rainfall variability, whereas perennially wet conditions diminish interannual variability in photosynthesis across much of the Congo Basin and coastal West Africa. Though not of focus here, the coefficient of variation in photosynthesis is notably high in drylands and desert margins (i.e., Sahel, Greater Horn, Namib, and Kalahari) having implications for supply of food and fiber. These findings emphasize that when considering impacts of climate change and land surface feedbacks to the atmosphere, it is important to recognize how vegetation, climate, and soil characteristics may conspire to filter or dampen ecosystem responses to hydroclimatic variability. Copyright 2008 by the American Geophysical Union
New Methods for Measurements of Photosynthesis from Space
Our ability to close the Earth's carbon budget and predict feedbacks in a warming climate
depends critically on knowing where, when, and how carbon dioxide (CO2) is exchanged
between the land and atmosphere. In particular, determining the rate of carbon fixation by
the Earth's biosphere (commonly referred to as gross primary productivity, or GPP) and the
dependence of this productivity on climate is a central goal. Historically, GPP has been
inferred from spectral imagery of the land and ocean. Assessment of GPP from the color of
the land and ocean requires, however, additional knowledge of the types of plants in the
scene, their regulatory mechanisms, and climate variables such as soil moistureâjust the
independent variables of interest!
Sunlight absorbed by chlorophyll in photosynthetic organisms is mostly used to drive
photosynthesis, but some can also be dissipated as heat or reâradiated at longer wavelengths
(660â800 nm). This nearâinfrared light reâemitted from illuminated plants is termed solarinduced
fluorescence (SIF), and it has been found to strongly correlate with GPP. To advance
our understanding of SIF and its relation to GPP and environmental stress at the planetary
scale, the Keck Institute for Space Studies (KISS) convened a workshopâheld in Pasadena,
California, in August 2012âto focus on a newly developed capacity to monitor chlorophyll
fluorescence from terrestrial vegetation by satellite. This revolutionary approach for
retrieving global observations of SIF promises to provide direct and spatially resolved
information on GPP, an ideal bottomâup complement to the atmospheric net CO2 exchange
inversions.
Workshop participants leveraged our efforts on previous studies and workshops related to
the European Space Agencyâs FLuorescence EXplorer (FLEX) mission concept, which had
already targeted SIF for a possible satellite mission and had developed a vibrant research
community with many important publications. These studies, mostly focused on landscape,
canopy, and leafâlevel interpretation, provided the groundâwork for the workshop, which
focused on the global carbon cycle and synergies with atmospheric net flux inversions.
Workshop participants included key members of several communities: plant physiologists
with experience using active fluorescence methods to quantify photosynthesis; ecologists
and radiative transfer experts who are studying the challenge of scaling from the leaf to
regional scales; atmospheric scientists with experience retrieving photometric information
from spaceâborne spectrometers; and carbon cycle experts who are integrating new
observations into models that describe the exchange of carbon between the atmosphere,
land and ocean. Together, the participants examined the link between âpassiveâ fluorescence
observed from orbiting spacecraft and the underlying photochemistry, plant physiology and
biogeochemistry of the land and ocean.
This report details the opportunity for forging a deep connection between scientists doing
basic research in photosynthetic mechanisms and the more applied community doing
research on the Earth System. Too often these connections have gotten lost in empiricism
associated with the coarse scale of global models. Chlorophyll fluorescence has been a major
tool for basic research in photosynthesis for nearly a century. SIF observations from space,
although sensing a large footprint, probe molecular events occurring in the leaves below.
This offers an opportunity for direct mechanistic insight that is unparalleled for studies of
biology in the Earth System.
A major focus of the workshop was to review the basic mechanisms that underlie this
phenomenon, and to explore modeling tools that have been developed to link the biophysical
and biochemical knowledge of photosynthesis with the observableâin this case, the
radiance of SIFâseen by the satellite. Discussions led to the identification of areas where
knowledge is still lacking. For example, the inability to do controlled illumination
observations from space limits the ability to fully constrain the variables that link
fluorescence and photosynthesis.
Another focus of the workshop explored a âtopâdownâ view of the SIF signal from space.
Early studies clearly identified a strong correlation between the strength of this signal and
our best estimate of the rate of photosynthesis (GPP) over the globe. New studies show that
this observation provides improvements over conventional reflectanceâbased remote
sensing in detecting seasonal and environmental (particularly drought related) modulation
of photosynthesis. Apparently SIF responds much more quickly and with greater dynamic
range than typical greenness indices when GPP is perturbed. However, discussions at the
workshop also identified areas where topâdown analysis seemed to be âout in frontâ of
mechanistic studies. For example, changes in SIF based on changes in canopy light
interception and the light use efficiency of the canopy, both of which occur in response to
drought, are assumed equivalent in the topâdown analysis, but the mechanistic justification
for this is still lacking from the bottomâup side.
Workshop participants considered implications of these mechanistic and empirical insights
for largeâscale models of the carbon cycle and biogeochemistry, and also made progress
toward incorporating SIF as a simulated output in land surface models used in global and
regionalâscale analysis of the carbon cycle. Comparison of remotely sensed SIF with modelsimulated
SIF may open new possibilities for model evaluation and data assimilation,
perhaps leading to better modeling tools for analysis of the other retrieval from GOSAT
satellite, atmospheric CO2 concentration. Participants also identified another application for
SIF: a linkage to the physical climate system arising from the ability to better identify
regional development of plant water stress. Decreases in transpiration over large areas of a
continent are implicated in the development and âlockingâinâ of drought conditions. These
discussions also identified areas where current land surface models need to be improved in
order to enable this research. Specifically, the radiation transport treatments need dramatic
overhauls to correctly simulate SIF.
Finally, workshop participants explored approaches for retrieval of SIF from satellite and
groundâbased sensors. The difficulty of resolving SIF from the overwhelming flux of reflected
sunlight in the spectral region where fluorescence occurs was once a major impediment to
making this measurement. Placement of very high spectral resolution spectrometers on
GOSAT (and other greenhouse gasâsensing satellites) has enabled retrievals based on infilling
of solar Fraunhofer lines, enabling accurate fluorescence measurements even in the
presence of moderately thick clouds. Perhaps the most interesting challenge here is that
there is no readily portable groundâbased instrumentation that even approaches the
capability of GOSAT and other planned greenhouse gas satellites. This strongly limits scientistsâ ability to conduct groundâbased studies to characterize the footprint of the GOSAT
measurement and to conduct studies of radiation transport needed to interpret SIF
measurement.
The workshop results represent a snapshot of the state of knowledge in this area. New
research activities have sprung from the deliberations during the workshop, with
publications to follow. The introduction of this new measurement technology to a wide slice
of the community of Earth System Scientists will help them understand how this new
technology could help solve problems in their research, address concerns about the
interpretation, identify future research needs, and elicit support of the wider community for
research needed to support this observation.
Somewhat analogous to the original discovery that vegetation indices could be derived from
satellite measurements originally intended to detect clouds, the GOSAT observations are a
rare case in which a (fortuitous) global satellite dataset becomes available before the
research community had a consolidated understanding on how (beyond an empirical
correlation) it could be applied to understanding the underlying processes. Vegetation
indices have since changed the way we see the global biosphere, and the workshop
participants envision that fluorescence can perform the next indispensable step by
complementing these measurements with independent estimates that are more indicative of
actual (as opposed to potential) photosynthesis. Apart from the potential FLEX mission, no
dedicated satellite missions are currently planned. OCOâ2 and â3 will provide much more
data than GOSAT, but will still not allow for regional studies due to the lack of mapping
capabilities. Geostationary observations may even prove most useful, as they could track
fluorescence over the course of the day and clearly identify stressârelated downâregulation of
photosynthesis. Retrieval of fluorescence on the global scale should be recognized as a
valuable tool; it can bring the same quantum leap in our understanding of the global carbon
cycle as vegetation indices once did
- âŠ