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A thermal sharpening algorithm (TsHARP) providing fine resolution land surface temperature (LST) to the Two-Source- Model (TSM) for mapping evapotranspiration (ET) was applied over two agricultural regions in the U.S. One site is a rainfed corn and soybean production region in central Iowa, while the other is an irrigated agricultural area in the Texas High Plains. Application of TsHARP to coarse (1 km) resolution thermal data over the rainfed agricultural area is found to produce reliable fine/within-field (60 m) resolution ET estimates, while in contrast, the TsHARP algorithm applied to the irrigated area does not perform as well, possibly due to significant sub-pixel moisture variations from irrigation. As a result, there may be little benefit in applying TsHARP for generating TSM-derived 60 m ET maps for the irrigated compared to the rainfed region. Consequently, reliable estimation of fine/within-field ET and crop stress still requires fine native resolution thermal imagery in areas with significant sub-pixel moisture variations.

[1] In semi-arid regions the evapotranspiration rates depend on both the spatial distribution of the vegetation and the soil moisture, for a given radiation regime. Remote sensing can provide high resolution spatially distributed estimation (o ∼ 10–100 m) of land surface states. However, data on the near surface air properties are not readily available at the same resolution and are often taken as spatially uniform over a greater region. Concern for how this scale mismatch might lead to erroneous flux estimations motivates this effort. This paper examines the relative roles of variability in the two dominant atmospheric states, wind speed and air temperature, on the variability of the surface fluxes. The study is conducted with a Large Eddy Simulation (LES) model of the Atmospheric Boundary Layer (ABL), where the boundary conditions are given by a surface energy balance model based on remotely sensed land surface data. Simulations have been performed for the late morning hours of two clear-sky summer days during the SGP97 experiment with different wetness conditions over an area characterized by a high contrast in surface temperature, canopy cover, and roughness between vegetated and dry bare soil areas. Spatial variability in canopy density effects both the air temperature Ta, through the energy partitioning, and the wind speed U, via the roughness, leading to local variations at 5 m above the ground of the order of 1 K and 1 m/s, respectively. Simulations show that the Ta variability tends to decrease the sensible heat flux H (− 30 W/m2) over bare soil areas and to increase it (+30 W/m2) over dense vegetation, thus reducing the total variability of the surface fluxes relative to those that would be estimated for spatially constant Ta, as observed in previous studies. The variability in U tends to increase H over bare soil (+50 W/m2), while having negligible effects over the vegetation, thus increasing the spatial variance of surface fluxes. However, when considered together, the combined effect is limited ( 50%) in the estimation of the evaporative fraction EF.

[1] Robust satellite-derived moisture stress indices will be beneficial to operational drought monitoring, both in the United States and globally. Using thermal infrared imagery from the Geostationary Operational Environmental Satellites (GOES) and vegetation information from the Moderate Resolution Imaging Spectrometer (MODIS), a fully automated inverse model of Atmosphere-Land Exchange (ALEXI) has been used to model daily evapotranspiration and surface moisture stress over a 10-km resolution grid covering the continental United States. Examining monthly clear-sky composites for April–October 2002–2004, the ALEXI evaporative stress index (ESI) shows good spatial and temporal correlation with the Palmer drought index but at considerably higher spatial resolution. The ESI also compares well to anomalies in monthly precipitation fields, demonstrating that surface moisture has an identifiable thermal signature that can be detected from space, even under dense vegetation cover. Simple empirical thermal drought indices like the vegetation health index do not account for important forcings on surface temperature, such as available energy and atmospheric conditions, and can therefore generate spurious drought detections under certain circumstances. Surface energy balance inherently incorporates these forcings, constraining ESI response in both energy- and water-limited situations. The surface flux modeling techniques described here have demonstrated skill in identifying areas subject to soil moisture stress on the basis of the thermal land surface signature, without requiring information regarding antecedent rainfall. ALEXI therefore may have potential for operational drought monitoring in countries lacking well-established precipitation measurement networks.

[1] Due to the influence of evaporation on land-surface temperature, thermal remote sensing data provide valuable information regarding the surface moisture status. The Atmosphere-Land Exchange Inverse (ALEXI) model uses the morning surface temperature rise, as measured from a geostationary satellite platform, to deduce surface energy and water fluxes at 5–10 km resolution over the continental United States. Recent improvements to the ALEXI model are described. Like most thermal remote sensing models, ALEXI is constrained to work under clear-sky conditions when the surface is visible to the satellite sensor, often leaving large gaps in the model output record. An algorithm for estimating fluxes during cloudy intervals is presented, defining a moisture stress function relating the fraction of potential evapotranspiration obtained from the model on clear days to estimates of the available water fraction in the soil surface layer and root zone. On cloudy days, this stress function is inverted to predict the soil and canopy fluxes. The method is evaluated using flux measurements representative at the watershed scale acquired in central Iowa with a dense flux tower network during the Soil Moisture Experiment of 2002 (SMEX02). The gap-filling algorithm reproduces observed fluxes with reasonable accuracy, yielding ∼20% errors in ET at the hourly timescale, and 15% errors at daily timesteps. In addition, modeled soil moisture shows reasonable response to major precipitation events. This algorithm is generic enough that it can easily be applied to other thermal energy balance models. With gap-filling, the ALEXI model can estimate hourly surface fluxes at every grid cell in the U.S. modeling domain in near real-time. A companion paper presents a climatological evaluation of ALEXI-derived evapotranspiration and moisture stress fields for the years 2002–2004.

[1] Uncertainties in assessing the effects of global-scale perturbations on the climate system arise primarily from an inadequate understanding of the hydrological cycle: on land, in oceans, and in the atmosphere and biosphere. Because of this uncertainty, almost all science-based initiatives have expressed the need for continued advances in global observations and modeling of the Earth system. It is in this spirit that we advocate establishing a hydrologic remote sensing observatory (RSO) to advance sensing technologies and their use in scientific inquiry into hydrologic processes. There are two fundamental reasons why establishing such a RSO is timely. The first is operational: Developing assimilation techniques to estimate unobserved fluxes and uncertainties in hydrologic forecasts has sufficiently matured to take advantage of computing facilities and detailed hydrologic observations shaped by the RSO. The second is scientific: This RSO will permit us to refine knowledge from physical and hydrologic models that can then be converted to local and global strategies for water resources management and ecosystem health evaluation. The authors outline the conceptual design, scope, and functionality of a RSO and present four examples to illustrate how the hydrologic community can take advantage of such facility.

Both one‐source and two‐source parameterizations of surface sensible heat flux exchange using radiometric surface temperature have been proposed. Although one‐source algorithms may provide reliable heat fluxes, they often require field calibration and hence are unable to accommodate the diverse range of surface conditions often encountered over a landscape. Two‐source models require fewer assumptions and no a priori calibration, and therefore have a wider range of applicability without requiring any additional input data. A one‐source scheme (SEBAL) that performs an “internal calibration” using hydrologic extremes (hot/dry and wet/cool pixels) encountered within a remote sensing scene has been proposed as a way to eliminate a priori calibration and the need for ancillary data. In this paper, some of the key assumptions in SEBAL are evaluated using a two‐source model, field data, and simulations from a complex soil‐vegetation‐atmosphere transfer (SVAT) model, Cupid.

Plant foliage density expressed as leaf area index (LAI) is an important parameter that is widely used in many ecological, meteorological and agronomic models. LAI retrieval using optical remote sensing usually requires the collection of surface calibration values or the use of image information to invert radiative transfer models. A comparison of LAI retrieval methods was conducted that included both empirical methods requiring ground based LAI calibration measurements and image based methods using remotely sensed data and literature reported parameter values. The empirical approaches included ordinary least squares regression with the Normalized Difference Vegetation Index (NDVI) and the Gitelson green index (GI) spectral vegetation indices (SVI) and a geostatistical approach that uses ground based LAI measurements and image derived kriging parameters to predict LAI. The image based procedures included the scaled SVI approach, which uses NDVI to estimate fraction of vegetation cover, and a hybrid approach that uses a neural network and a radiative transfer model to retrieve LAI. Comparable results were obtained with the empirical SVI methods and the scaled SVI method. The geostatistical approach produced LAI patterns similar to interpolated ground-based LAI measurements. The results demonstrated that although reasonable LAI estimates are possible using optical remote sensing data without in situ calibration measurements, refinements to the analytical steps of the various approaches are warranted.

Abstract Routine estimates of daily incoming solar radiation from the GOES-8 satellite were compared to locally measured values in Florida. Longwave radiation estimates corrected using GOES-derived cloud amount and cloud top temperature products improved net radiation estimates as compared to a clear sky longwave approach. The Penman-Monteith, Turc, Hargreaves and Makkink models were applied using GOES-derived estimates of solar radiation and net radiation to predict daily evapotranspiration and were compared to evapotranspiration measured with an eddy-correlation system in an emergent wetland experimental site in north-central Florida under unstressed conditions. While the Penman-Monteith model provided the best estimates of evapotranspiration (R 2 = 0.92), the empirical Makkink method demonstrated nearly comparable agreement (R 2 = 0.90) using only the GOES solar radiation and measured temperature. The results show that it is possible to generate spatially distributed daily potential evapotrans...

[1] Many applications exist within the fields of agriculture, forestry, land management, and hydrologic assessment for routine estimation of surface energy fluxes, particularly evapotranspiration (ET), at spatial resolutions of the order of 101 m. A new two-step approach (called the disaggregated atmosphere land exchange inverse model, or DisALEXI) has been developed to combine low- and high-resolution remote sensing data to estimate ET on the 101–102 m scale without requiring any local observations. The first step uses surface brightness-temperature-change measurements made over a 4-hour morning interval from the GOES satellite to estimate average surface fluxes on the scale of about 5 km with an algorithm known as ALEXI. The second step disaggregates the GOES 5-km surface flux estimates by using high-spatial-resolution images of vegetation index and surface temperature, such as from ASTER, Landsat, MODIS, or aircraft, to produce high-spatial-resolution maps of surface fluxes. Using data from the Southern Great Plains field experiment of 1997, the root-mean-square difference between remote estimates of surface fluxes and ground-based measurements is about 40 W m−2, comparable to uncertainties associated with micrometeorological surface flux measurement techniques. The DisALEXI approach was useful for estimating field-scale, surface energy fluxes in a heterogeneous area of central Oklahoma without using any local observations, thus providing a means for scaling kilometer-scale flux estimates down to a surface flux-tower footprint. Although the DisALEXI approach is promising for general applicability, further tests with varying surface conditions are necessary to establish greater confidence.

Presents an operational two-source (soil+vegetation) time-integrated model (TSTIM) for estimating energy fluxes from a vegetated surface given measurements of the time rate of change of radiometric surface temperature (T/sub RAD/). This model requires ancillary measurements of wind speed, albedo, vegetation type and cover and initial atmospheric lapse rate. Unlike most algorithms for flux estimation proposed to date, however, this method does not require in situ measurements of air temperature. This is a significant benefit when T/sub RAD/ is acquired remotely and it is difficult to collocate surface and air temperature measurements. The dependence of apparent radiometric temperature on sensor view angle is taken into account, so off-nadir satellite measurements can be used to drive the model. When applied to surface data collected during the FIFE and Monsoon '90 field experiments, RMS deviations between measurements and model predictions were comparable to those achieved by models that do require air temperature as an input, and to measurement errors typical of standard micrometeorological methods for flux estimation.

Light-use-efficiency (LUE), which is the ratio of carbon dioxide uptake to intercepted photosynthetically active radiation (IPAR) for a plant canopy, is a simple way to characterize plant productivity. By combining the concept of LUE with a stomatal-response model for leaves that is adapted to canopies, the authors have derived a simple analytical biophysical (SAB) model of canopy assimilation and conductance that agrees with a detailed soil-plant-atmosphere model named Cupid under a range of conditions. Assimilation predictions from this SAB model include effects of IPAR, carbon dioxide concentration, atmospheric humidity, temperature and available soil water. This SAB model has been integrated into a two-source model for estimating surface energy balance components from satellite observations (vegetation index, albedo, surface radiometric temperature) along with plant type and ground measurements of wind speed and atmospheric lapse rates. By obtaining an estimate of vapor pressure near the surface, which is possible from a combination of surface synoptic network measurements and sunrise surface temperature measurements from a satellite like GOES, the LUE can be estimated. Predictions from the SAB model compare reasonably with measurements from FIFE.

For the past few years, we have been involved in an effort to develop a Desktop Experiment Management Environment that many experimental scientists would like to have on their desk. The environment is called ZOO and is developed in collaboration with domain scientists from several disciplines. In this short paper, we first describe the overall architecture of ZOO and then discuss the particular experiment on the hydrological cycling of water through a landscape that we are demonstrating at SSDBM-9.

Polymerization of a mutated form of antitrypsin is postulated to cause serpinopathy, a rare and incurable genetic disease. Antitrypsin is the canonical member of the serpin superfamily of structurally homologous proteins with metastable native structures. Most of serpins, including antitrypsin, are regulators of serine and cysteine protease cascades, and protect tissues from excessive actions of extracellular proteolytic enzymes. Polymerization of the mutant Z variant of antitrypsin results in the “loss of function” proteolytic damage of lungs, or in the “gain of function” degeneration of liver cells, loaded with toxic polymers. The understanding of polymerization mechanism holds the key to disease prevention, diagnostics and cures. However, metastability of serpins and complexity of their polymers makes structural studies a difficult task. There are several models of polymerization, based on in vitro studies and molecular modeling, however their relevance to in vivo polymerization and disease etiology has not been established. Here we employed atomic force microscopy (AFM) to compare topography of in vitro and in vivo formed antitrypsin polymers and oligomers. We found that commonly used in vitro methods to induce polymerization result in formation of topographically a very diverse population of oligomers. Most, if not all classes of the in vitro formed oligomers corresponded to similar classes of oligomers isolated from liver. The in vitro polymerization, however did not produce long strands of polymerized antitrypsin. The presence of such strands is the most striking feature in liver cells of human serpinopathy patients and in a mouse model. Here, we report results of our scanning probe microscopy structural analysis of long serpin polymers and propose the mechanism of their formation.

We compare the radio and soft X-ray brightness as a function of position within the young supernova remnant Cassiopeia A. A moderately strong correlation (r = 0.7) was found between the X-ray emission (corrected for interstellar absorption) and radio emission, showing that the thermal and relativistic plasmas occupy the same volumes and are regulated by common underlying parameters. The logarithmic slope of the relationship, ln(Sx-ray) = 1.2 x Sradio + ln(k) implies that the variations in brightness are primarily due to path length differences. The X-ray and radio emissivities are both high in the same general locations, but their more detailed relationship is poorly constrained and probably shows significant scatter. The strongest radio and X-ray absorption is found at the western boundary of Cas A. Based on the properties of Cas A and the absorbing molecular cloud, we argue that they are physically interacting. We also compare ASCA derived column densities with 21 cm H I and 18 cm OH optical depths in the direction of Cas A, in order to provide an independent estimate of ISM properties. We derive an average value for the H I spin temperature of about 40 K and measure the ratio of OH to molecular hydrogen to be nominally larger than previous estimates. Keywords: Cas A, Cassiopeia A, interstellar medium, molecular clouds, radio astronomy, supernova remnants, X-ray astronomy, To appear in Vol. 446 of The Astrophysical Journal on Aug. 1, 1996; 10 pages with 5 embedded figures; replaced because of updated references

Leaf area index (LAI) is a key parameter in most land surface models. Models that operate at multiple spatial scales may require consistent LAI inputs at different spatial resolutions or from different sensors. For example, the atmosphere-land exchange inverse model and associated disaggregation algorithm (DisALEXI) use the moderate resolution imaging spectroradiometer (MODIS) LAI product to model fluxes at regional scales (1- to 10-km grid resolution), and Landsat-based LAI to disaggregate to field scale (30-m grid). In order to make a MODIS-consistent LAI product from Landsat imagery for this combined scheme, a simple reference-based regression tree approach was developed. This approach uses homogeneous and high-quality LAI retrievals from MODIS as references to develop a regression tree relating these MODIS LAI samples to Landsat surface reflectances. Results show that the approach can produce accurate estimates of LAI from Landsat, as evaluated using field measurements collected during the soil moisture experiment of 2002, conducted in central Iowa during a period of rapid vegetation growth. The coefficient of determination (r2) computed between Landsat retrievals and field measurements was 0.94 at the field scale, with an overall mean bias error (MBE) of −0.07 and mean absolute difference (MAD) of 0.23. MAD values of 0.17 and 0.32 were obtained for low to moderate LAI (0-3) and high LAI (>3), respectively, with some underestimation for the high LAI (MBE = −0.28). The LAI maps retrieved from Landsat were consistent with the MODIS estimates when aggregated to coarser scales. MAD computed between Landsat- and MODIS-derived LAI ranged from 0.07 to 0.83 for different Landsat dates, with no significant bias compared to MODIS high-quality retrievals. This approach demonstrates a simple framework for producing MODIS-consistent LAI from Landsat data for modeling the land surface at different spatial scales.

Serpins belong to a superfamily of structurally homologous proteins with metastable native structures. Their metastability is crucial in performing their function as regulators of serine and cysteine protease cascades. However, mutated variants of serpins found in patients with serpinopathies are often prone to polymerization. The most widespread serpinopathy is related to the Z variant of antitrypsin, which forms toxic polymers in the liver leading to liver degeneration. The understanding of polymerization mechanism holds the key to disease prevention, diagnostics and cures. Several models of serpin polymerization have been proposed. Still, the structure of in vivo formed polymers is unknown, and the relevance of in vitro created oligomers to disease related structures is far from established. Here we employed atomic force microscopy (AFM) to compare topography of in vitro and in vivo formed antitrypsin polymers and oligomers. We established morphometric features of Z monomers and in vitro formed dimers with different types of linkage. Moreover, we found a remarkable heterogeneity of unit types and their arrangement in polymer strands isolated from the Z variant mutant mouse liver. Even within the same strand there were examples of a linear arrangement of monomer units and of compact arrangement of dimers. The in vitro formed wild type oligomer preparations contained structures resembling the native Z variant structures from the liver. Still, the partition of types of polymers was strikingly distinct, with compact monomer arrangement and polymerized dimers frequenting the in vitro samples. In addition to AFM, we used scanning tunneling microscopy (STM) to study the orientation of units in polymers based on the proteins surface charge. Summarizing, SPM imaging provided the unique data on a high heterogeneity of polymers and pointed at certain types of monomer linkages that might help explain the mechanism of serpin polymerization.

We discuss ways in which radio continuum observations of shell supernova remnants can be applied to the study of astrophysical particle acceleration. As an example, radio observations of SNRs Cas A, G39.2–0.3, and G41.1–0.3 are presented.

In this paper, we discuss the types of observations used to study the acceleration of relativistic electrons in the diffuse plasma of extragalactic radio sources. The goal of this work is to identify the conditions under which such acceleration is important and which acceleration processes dominate. We identify some of the pitfalls in such analyses and suggest directions for future work.

This paper describes a novel physically-based approach for estimating leaf area index (LAI) and leaf chlorophyll content (Cab) at regional scales that relies on radiance data acquirable from a suite of aircraft and operational satellite sensors. The REGularized canopy reFLECtance (REGFLEC) modeling tool integrates leaf optics (PROSPECT), canopy reflectance (ACRM), and atmospheric radiative transfer (6SV1) model components, facilitating the direct use of at-sensor radiances in green, red and near-infrared wavelengths. REGFLEC adopts a multi-step LUT-based inversion approach and incorporates image-based techniques to reduce the confounding effects of land cover specific vegetation parameters and soil reflectance. REGFLEC was applied to agricultural and natural vegetation areas using 10 m and 20 m resolution SPOT imagery, and variable environmental and plant development conditions allowed for model validation over a wide range in LAI (0 - 6) and Cab (20 - 75 µg cm-2). Validation against in-situ measurements yielded relative root-mean-square deviations on the order of 13% (0.4) for LAI and between 11 - 19% (4.9 - 9.1 µg cm-2) for Cab. REGFLEC demonstrated good utility in detecting spatial and temporal variations in LAI and Cab without requiring site-specific data for calibration. The physical approach presented here can quite easily be applied to other regions and has the potential of being more universally applicable than traditional empirical approaches for retrieving LAI and Cab.

[Figure][1] Free image. This Landsat 5 image of the southeastern corner of the Black Sea is part of the general U.S. archive that will be accessible for free under the new USGS policy. CREDIT: BOSTON UNIVERSITY CENTER FOR REMOTE SENSING We are entering a new era in the Landsat Program, the oldest and most venerable of our Earth-observing satellite programs. With little fanfare, the U.S. Geological Survey (USGS) has begun providing imagery for free over the Internet. Throughout the history of the Landsat Program, the cost and access to imagery has always limited our ability to study our planet and the way it is changing. Beginning with a pilot program to provide “Web-enabled” access to Landsat 7 images of the United States that were collected between 2003 and this year, the USGS now plans to provide top-quality image products for free upon request for the entire U.S. archive, including over 2 million images back to Landsat 1 (1972) [for details and schedules, see ([1][2])]. The release by NASA and the USGS in January 2008 of a new Landsat Data Distribution Policy ([2][3]) was a key step to this goal. Free imagery will enable reconstruction of the history of Earth's surface back to 1972, chronicling both anthropogenic and natural changes during a time when our population doubled and the impacts of climate change became noticeable. The Landsat Science Team: 1. 1.[↵][4]USGS Technical Announcement ([http://landsat.usgs.gov/images/squares/USGS\_Landsat\_Imagery_Release.pdf][5]). 2. 2.[↵][6]Landsat Missions ([http://ldcm.usgs.gov/pdf/Landsat\_Data\_Policy.pdf][7]). [1]: pending:yes [2]: #ref-1 [3]: #ref-2 [4]: #xref-ref-1-1 "View reference 1. in text" [5]: http://landsat.usgs.gov/images/squares/USGS_Landsat_Imagery_Release.pdf [6]: #xref-ref-2-1 "View reference 2. in text" [7]: http://ldcm.usgs.gov/pdf/Landsat_Data_Policy.pdf

W etlands provide many beneficial functions, including the reduction of pollutants and floodwater mitigation. These functions are performed through the interaction of multiple landscape components (e.g., agricultural fields, forests, urban areas, and wetlands) and therefore should be considered at the watershed scale. Wetland hydrology (i.e., flooding and soil moisture) controls ecosystem function and must be better understood to conserve remaining wetlands, monitor wetland function, and improve water quality management. The ability to monitor forested wetlands is particularly important because these ecosystems make up over half of all freshwater wetlands in the United States and are often found adjacent to croplands, where they are well-situated to reduce agrochemicals in runoff from nearby fields. Wetland hydrology is dynamic, varying at multiple temporal scales (e.g., seasonal and inter-annual) and therefore should be assessed regularly. Unfortunately, broad-scale forested wetland hydrology is difficult to monitor at all temporal scales using ground-based and traditional remote sensing methods (i.e., aerial photography). Satellite-borne radar data can provide both high spatial and temporal resolution information on wetland hydrology in forested areas, but the full potential of this approach needs further investigation. Research is being conducted to evaluate the use of radar data for monitoring forested wetland hydrology in the Choptank …

Water lost to the atmosphere through evapotranspiration (ET; soil evaporation + canopy transpiration) serves to cool the Earth's surface. Just as a thermometer is used to diagnose stress in the human body, land surface temperature (LST) derived from remote sensing data in the thermalinfrared (TIR) band (8–14 microns) is a valuable diagnostic of biospheric stress resulting from soil moisture deficiencies. Soil surface temperature increases with decreasing water content, while moisture depletion in the plant root zone leads to stomatal closure, reduced transpiration, and elevated canopy temperatures that can be effectively detected from space. In land surface modeling, TIR imagery can serve as an effective substitute for precipitation data, providing much needed water information in data-poor regions of the world.

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Numerical simulations describing the dynamical and radiative evolution of clumpy supernova ejecta are compared with observations of optical and radio emission knots in supernova remnant (SNR) Cassiopeia A. Three major phases are identified in the evolution of clumpy ejecta: a bow-shock phase, an instability phase, and a dispersal phase. The phenomenological and radiative signatures of each phase are discussed and compared with multi-epoch measurements of small-scale features in Cas A. Good correspondence is found between theory and observations. Both support the premise that compact radio emission features are controlled more by magnetic field amplification triggered in the instability phase than by in situ acceleration of new relativistic particles.

Spatial variations are observed in the synchrotron spectra of Galactic shell supernova remnants G39.2-0.3 and G41.1 -0.3 (3C 396 and 3C 397). Spectral indices in these remnants, as measured between λ6 and 20 cm, vary on the order of Δα∼0.2. In neither remnant do the spectral variations correlate well with features in total radio intensity. Explanations for these variations are sought in terms of various models of astrophysical particle acceleration. In comparing G39.2-0.3 and G41.1-0.3 with seven other shell remnants exhibiting spatially varying spectral indices, we find that in the older of these remnants, brighter regions tend to be flatter. In the younger remnants, the highest emissivity regions are generally the steepest, but with notable exceptions

We present an innovative technique for determining the shape of the synchrotron spectra in extended radio sources. This method involves a three-frequency color-color diagram that emphasizes differences in the shapes of various theoretical models. The advantages of this technique over standard multifrequency mapping are that (1) it is easy to collect the necessary data (only three frequencies required), (2) it highlights the curvature changes in the spectrum, and (3) it puts data from all regions of the source onto one plane; and if a global spectrum exists, (4) it allows for effectively continuous sampling in frequency, (5) it provides sampling over a much larger range of electron energies, and (6) both the shape of the spectrum and the injection index, if it exists, can be determined by three-frequency data

Spectral index variations are observed in the radio brightness distribution in the supernova remnant Cassiopeia A, between observing wavelengths of 20 and 6 cm. Reliable variations are seen over a range of {minus}0.64 to {minus}0.92, with steeper spectra typically associated with compact features such as the 'bow shocks' and flatter spectra with the bright radio ring. The spatial scales over which significant variations are detected range from about 11 arcsec to greater than 80 arcsec. These results indicate a direct link between the dynamics of the remnant and the relativistic particle energy distributions. Building on previously suggested dynamical pictures, it is suggested that the bow shocks are caused by moderately dense clumps of ejecta newly encountering the shocked ISM. It is found that models based on first-order Fermi acceleration in the test particle limit are unable to explain, concurrently, the steep spectral indices and the high synchrotron emissivities observed in Cas A. Thus, consideration of other types of processes, such as acceleration in cosmic-ray-mediated shocks and turbulent acceleration with secularly increasing B fields, is required. 35 refs.

High-resolution (0.36 arcsec, 0.41 kpc) observations of the northern hot spot of the radio galaxy 3C 33 show a symmetric mushroom cap structure, with a centrally placed H-shaped feature and two opposed small bright regions. Two models for the flow patterns in this hot spot are explored. The first is the 'splash' picture, in which the brightest compact feature is identified as the primary hot spot and the rest of the structures result from the jet's expanded, deflected flow. Although most observed features are consistent with this picture, they do not help discriminate against alternative models. The second, axisymmetric, picture compares the observations with numerical simulations of jets with helical magnetic fields. Good agreement was found with the geometrical and magnetic field properties, although significant questions remain about the synchrotron emissivity characteristics. The differences between the northern and southern hot spots of 3C 33 are briefly discussed, and it is suggested that there are no good explanations for these differences in the context of current models. 28 refs.

Reactions after booster injections of human diploid cell rabies vaccine (HDCV) were investigated to determine the possibility of IgE-type antibody involvement. Although normal manufacture of HDCV involves the inactivation of the virus with β-propiolactone (BPL), the effect of BPL on nonviral vaccine components, such as host cell components or stabilizing proteins, may be typical of the haptenic action of small molecular weight chemicals. Specific IgE to commercial HDCV preparations, BPL-treated preparations of noninfected host MRC5 cell sonicate (BPL-MRC5), and a human albumin (HA) (BPL-HA) used as a stabilizing agent were detected in sera from five individuals who reported reactions after booster doses of HDCV. However, these patients had no detectable IgE to normal HA. Sera from nonvaccinated individuals, vaccinated individuals who reported no reaction after HDCV booster, and pollen-allergic individuals had no detectable IgE to HDCV, BPL-MRC5, or BPL-HA. Changes in the ratios of pre- to postbooster serum levels of specific IgE to HDCV and BPL-HA were significantly different in a group of 19 individuals who reported reactions to HDCV boosters; these changes in pre- to postbooster IgE levels in nonreactive vaccinees were not significant. Prebooster serum IgE RAST ratios to HDCV or BPL-HA were not predictive of potential reactions to HDCV. A number of experimental BPL-HA reaction mixtures were assayed to examine the effect of variable concentrations of BPL to HA. Increasing relative molar concentrations of BPL to HA resulted in increased electrophoretic mobility, whereas the highest relative specific IgE binding was detected in BPL-HA molar reaction mixtures of approximately 12.5:1. Specific IgE to nonviral HDCV components appears to be related to reactions after booster doses of BPL-inactivated HDCV.

In direct RAST analyses of sera from 43 individuals with a history of cat allergy, 39.5% were positive to cat pelt, 37.5% to cat saliva, and 12% each to cat urine and serum. The cat pelt and saliva extracts contained allergen 1, but cat serum and cat urine collected by bladder puncture had no detectable levels of this allergen. A crossed immunoelectrophoresis/crossed radioimmunoelectrophoresis analysis failed to reveal any allergen in urine or serum that was not also present in the saliva or pelt preparations, although urine had two allergens not present in serum. When serum from a patient who was direct RAST positive to cat pelt, serum, saliva, and urine was tested by crossed radioimmunoelectrophoresis, it was determined that a total of six allergens were detectable in cat pelt, three in cat urine, and six in cat serum. Since cat serum contains no detectable cat allergen 1, it may be concluded that at least seven allergens derived from the cat are capable of binding to IgE antibody in humans.

An in vitro model for the study of the pathogensis of silicosis is described. In it, filtered supernates from alveolar macrophage cultures incubated in contact with silica particles are added to target cultures of lung fibroblasts. The effects of this system are easily studied by observation for cytotoxicity and hydroxyproline production. These results confirm and extend the observations of Heppleston and Styles and point to the use of such a system for the in vitro study of the effects of silica.

Landsat 8, a NASA and USGS collaboration, acquires global moderate-resolution measurements of the Earth's terrestrial and polar regions in the visible, near-infrared, short wave, and thermal infrared. Landsat 8 extends the remarkable 40year Landsat record and has enhanced capabilities including new spectral bands in the blue and cirrus cloud-detection portion of the spectrum, two thermal bands, improved sensor signal-to-noise performance and associated improvements in radiometric resolution, and an improved duty cycle that allows collection of a significantly greater number of images per day. This paper introduces the current (2012–2017) Landsat Science Team's efforts to establish an initial understanding of Landsat 8 capabilities and the steps ahead in support of priorities identified by the team. Preliminary evaluation of Landsat 8 capabilities and identification of new science and applications opportunities are described with respect to calibration and radiometric characterization; surface reflectance; surface albedo; surface temperature, evapotranspiration and drought; agriculture; land cover, condition, disturbance and change; fresh and coastal water; and snow and ice. Insights into the development of derived ‘higher-level’ Landsat products are provided in recognition of the growing need for consistently processed, moderate spatial resolution, large area, long-term terrestrial data records for resource management and for climate and global change studies. The paper concludes with future prospects, emphasizing the opportunities for land imaging constellations by combining Landsat data with data collected from other international sensing systems, and consideration of successor Landsat mission requirements.

Governments, aid organizations and people affected by drought are struggling to mitigate the resulting impact on both water resources and crops. In this paper we focus on improved decision-support for agricultural droughts that threaten the livelihoods of people living in vulnerable regions. We claim that new strategic partnerships are required to link scientific findings to actual user requirements of governments and aid organizations and to turn data streams into useful information for decision-support. Furthermore, we list several promising approaches, ranging from the integration of satellite-derived soil moisture measurements that link atmospheric processes to anomalies on the land surface to improved long-range weather predictions and mobile applications. The latter can be used for the dissemination of relevant information, but also for validating satellite-derived datasets or for collecting additional information about socio-economic vulnerabilities. Ideally, the consequence is a translation of early warning into local action, strengthening disaster preparedness and avoiding the need for large-scale external support.

Eight sequentially collected lots of aqueous extracts of imported fire ant (IFA) front end and abdominal end segments were assayed for phospholipase A (PLA), N-acetyl-beta-glucosaminidase (NAG), and hyaluronidase. Relative potency of each extract lot and pooled venom was measured by RAST inhibition against a venom standard. More than a hundredfold difference in PLA activity was observed. Early summer collections had the highest activity. The May to June collection had more than twice the PLA activity of the next most potent lot. Discordancy in enzyme patterns was noted only in AE extract. NAG levels peaked earlier in the spring and summer and fluctuated less widely. Front end extract had lower activity levels for both enzymes, with no seasonal fluctuation in NAG and a single elevation in PLA activity in the April to May collection. RAST inhibition varied directly with PLA activity (p less than .05) but not with NAG nor hyaluronidase activities. Fifty-one percent of systemic allergic reactions to IFA stings occurred in summer, and 19% occurred in spring. A reported demographic survey demonstrated a higher incidence of IFA stings in the spring (39.9%) with a lower attack rate in the summer (31.9%). These findings suggest that the rate of systemic reactions to stings of the IFA may be related to seasonal variations in allergenic potency, as measured by PLA and RAST inhibition, rather than the sting attack rate.

Publisher Summary This chapter discusses allergenic extracts used to diagnose and treat allergies in man, and consist of water- or buffer-soluble proteins derived from plants, animals, insects, fungi, and foods. These proteins induce allergic response within minutes of exposure, and are found on the surface, or readily extractable, or secreted from the source material. Common allergens include pollen grains, dusts from animal skin surfaces, animal bedding materials, animal saliva and urine, and venoms of stinging insects, such as bees. The procedures found to be useful are polyacrylamide gel electrophoresis (PAGE), PAGE with the addition of sodium dodecyl sulphate (SDS-PAGE), isoelectric focusing (IEF), crossed immunoelectrophoresis (CIE), crossed radioimmunoelectrophoresis (CRIE), and to a limited extent, agar, or agarose gel immunoelectrophoresis. Immunoelectrophoresis is not a widely used technique and has limited sensitivity, but is used to examine the antigens produced by Aspergillus under different growth conditions.

H. Baer , T.-Y. Liu , M. C. Anderson , M. Blum , W. H. Schmid and F. J. James . Protein components of fire ant venom ( Solenopsis invicta ), Toxicon 17, 397–405, 1979.—Venom of the fire ant ( Solenopsis invicta ), long thought to contain only alkaloids, is shown to contain proteins, which undoubtedly accounts for the induction of anaphylactic reactions from stings. Failure of previous investigators to identify proteins in this venom is probably due to the low protein content of approximately 0·1% of the venom weight. In common with other hymenoptera venoms, it contains phospholipase and hyaluronidase activity. Sephadex chromatography showed the presence of at least 3 proteins which were allergenically active, as determined by RAST using sera of individuals allergic to fire ant sting. The RAST also indicated that S. invicta venom was different from the venoms of S. richteri, S. xyloni and S. geminata , but probably shows extensive cross-reactivity. Commercially prepared extracts were shown to contain venom by RAST.

A quantitative skin-test assay of allergenic potency was developed and tested on 28 allergic patients. The best-fit linear regression line was calculated from the sum of erythema or wheal diameters obtained from four intradermal threefold serial dilutions near the endpoint. Each line must have a correlation coefficient ≥0.85 and the slopes of reference and test extract lines must not be significantly different. The relative potency can be calculated from the horizontal distance between the reference and test lines. The between-assay reproducibility was determined by comparing references against themselves. The 95% confidence limits were 54% to 186% when erythema was used and 27% to 367% when wheal was used. The narrower limits for the assay using erythema may be due to the 5.5 times steeper slope of erythema lines than wheal lines. Potency results on five commercial extracts were highly correlated with potency results by RAST, AgE assay, or rye I assay. Extracts with isoelectric focusing patterns dissimilar from the references were of significantly lower potency by in vivo and in vitro assays. The measured potency of two low-potency short ragweed extracts varied significantly with patient sensitivity to heat-stable and heat-labile ragweed allergens, indicating that patient selection may significantly affect assay results. Dose-response lines using either histamine or short ragweed by puncture (P) and intradermal (ID) techniques in the same patient showed that the PID dose for equal erythema response was 909 for histamine and 31,250 for ragweed. This quantitative skin-text assay is highly reproducible, yields potency data comparable to those of in vitro tests, can be applied to studies of extract stability, and is suitable as a primary bioassay of allergenic activity.

The changes that occur in the antigens and allergens of a timothy grass pollen extract during storage were measured by radioallergosorbent test (RAST) inhibition, isoelectric focusing, (IEF), crossed immunoelectrophoresis (CIE) and crossed radioimmunoelectrophoresis (CRIE) and a dye-binding protein assay. Storage intervals varied from 7 to 92 days at temperatures of 4 degrees, 22 degrees, and 35 degrees C and the freeze-dried extract was rehydrated and stored in either phosphate-buffered saline with 50% glycerol (PBSG) or Coca's solution (CS). For extracts stored in CS at 35 degrees C, allergenic activity as measured by RAST inhibition dropped by almost one half at 7 days and certain of the IEF, CIE, ad CRIE bands were no longer visible, showing that these properties correlated with allergenic activity. After 65 dys, no IEF bands were visible but three CIE bands could be visualized. At 22 degrees the changes were slower and at 4 degrees C no changes were observed for the 92-day storage time. Extracts stored in PBSG showed some of the same changes but were much more stable at all temperatures. During storage, the protein content as measured by dye binding was also reduced, showing tha proteins were fragmenting. Because some of the allergenic proteins disappeared more rapidly than others, there was not only a loss in total allergenic activity but also a change in specificity. This raises serious questions concerning the use of such extracts, especially for diagnosis.

For at least four decades, archaeologists have identified irrigation as playing a potentially major role in the rise of Aksumite civilization. Based on a systematic survey covering the area between Aksum and Yeha (Ethiopia), Joseph Michels proposed that large-scale irrigation systems introduced from Southwest Arabia contributed to the rise of Yeha as a major center of Pre-Aksumite civilization. To evaluate spatial patterning of archaeological sites with respect to water availability, this paper reports on results from archaeological survey of a 100 km2 region surrounding Yeha conducted by the Southern Red Sea Archaeological Histories (SRSAH) Project from 2009 to 2016. The SRSAH Project recorded 84 sites dating from the Pre-Aksumite to the Post-Aksumite periods (c.800 BCE to 900 CE). No ancient irrigation systems were identified and results do not show a correlation between archaeological sites and water resources. This suggests that irrigation was less important than Michels contended and that rainfed agriculture, terraces, and small-scale irrigation comparable with practices evident in the region today were sufficient to sustain ancient populations.