Simulating sunflower canopy temperatures to infer root-zone soil water potential

A soil-plant-atmosphere model for sunflower (Helianthus annuus L.), together with clear sky weather data for several days, is used to study the relationship between canopy temperature and root-zone soil water potential. Considering the empirical dependence of stomatal resistance on insolation, air temperature and leaf water potential, a continuity equation for water flux in the soil-plant-atmosphere system is solved for the leaf water potential. The transpirational flux is calculated using Monteith's combination equation, while the canopy temperature is calculated from the energy balance equation. The simulation shows that, at high soil water potentials, canopy temperature is determined primarily by air and dew point temperatures. These results agree with an empirically derived linear regression equation relating canopy-air temperature differential to air vapor pressure deficit. The model predictions of leaf water potential are also in agreement with observations, indicating that measurements of canopy temperature together with a knowledge of air and dew point temperatures can provide a reliable estimate of the root-zone soil water potential

Diurnal patterns of wheat spectral reflectances and their importance in the assessment of canopy parameters from remotely sensed observations

Spectral reflectances of Produra wheat were measured at 13 different times of the day at Phoenix, Arizona, during April 1979 using a nadir-oriented hand-held 4-band radiometer which had bandpass characteristics similar to those on LANDSAT satellites. Different Sun altitude and azimuth angles caused significant diurnal changes in radiant return in both visible and near-IR regions of the spectrum and in several vegetation indices derived from them. The magnitude of these changes were related to different canopy architecture, percent cover and green leaf area conditions. Spectral measurements taken at each time period were well correlated with green leaf area index but the nature of the relationship changed significantly with time of day. Thus, a significant bias in the estimation of the green leaf area index from remotely sensed spectral data could occur if sun angles are not properly accounted for

Soil water content and evaporation determined by thermal parameters obtained from ground-based and remote measurements

A procedure is presented for calculating 24-hour totals of evaporation from wet and drying soils. Its application requires a knowledge of the daily solar radiation, the maximum and minimum, air temperatures, moist surface albedo, and maximum and minimum surface temperatures. Tests of the technique on a bare field of Avondale loam at Phoenix, Arizona showed it to be independent of season

Hand-held radiometry: A set of notes developed for use at the Workshop of Hand-held radiometry

A set of notes was developed to aid the beginner in hand-held radiometry. The electromagnetic spectrum is reviewed, and pertinent terms are defined. View areas of multiband radiometers are developed to show the areas of coincidence of adjacent bands. The amounts of plant cover seen by radiometers having different fields of view are described. Vegetation indices are derived and discussed. Response functions of several radiometers are shown and applied to spectrometer data taken over 12 wheat plots, to provide a comparison of instruments and bands within and among instruments. The calculation of solar time is reviewed and applied to the calculation of the local time of LANDSAT satellite overpasses for any particular location in the Northern Hemisphere. The use and misuse of hand-held infrared thermometers are discussed, and a procedure for photographic determination of plant cover is described. Some suggestions are offered concerning procedures to be followed when collecting hand-held spectral and thermal data. A list of references pertinent to hand-held radiometry is included

Epitope-targeted peptide inhibitors of Myc-Max Dimerization

Myc is a popular transcription factor that is found in about 30% of human cancers. Along with being present in many cancers, it is also a potent oncogenic driver. Myc dimerizes with Max in order to promote transcription of genes that are associated with cellular proliferation, differentiation, and survival. In cancers that are Myc-driven, the Myc concentrations are higher than in healthy cells. Developing drugs in which impede Myc-Max dimerization has been difficult because there are many interactions that occur over large interfaces. This project hypothesizes that using molecular peptide ligands that adsorb to Myc at the Myc-Max dimer interface will disrupt the intermolecular interactions between Myc-Max. Molecular screening is used to identify cyclic peptide ligands that will have a high binding affinity to epitopes on Myc. By using the peptide ligands, they can be tested to measure their affinity to the Mac protein, the location of the binding on Myc, and its ability to inhibit the formation of the dimer by Myc-Max. By having this data, it then can be used to engineer peptides that are potent inhibitors of Myc-Max dimerization

Airborne monitoring of crop canopy temperatures for irrigation scheduling and yield prediction

Airborne and ground measurements were made on April 1 and 29, 1976, over a USDA test site consisting mostly of wheat in various stages of water stress, but also including alfalfa and bare soil. These measurements were made to evaluate the feasibility of measuring crop temperatures from aircraft so that a parameter termed stress degree day, SDD, could be computed. Ground studies have shown that SDD is a valuable indicator of a crop's water needs, and that it can be related to irrigation scheduling and yield. The aircraft measurement program required predawn and afternoon flights coincident with minimum and maximum crop temperatures. Airborne measurements were made with an infrared line scanner and with color IR photography. The scanner data were registered, subtracted, and color-coded to yield pseudo-colored temperature-difference images. Pseudo-colored images reading directly in daily SDD increments were also produced. These maps enable a user to assess plant water status and thus determine irrigation needs and crop yield potentials

Understanding and optimizing the interactions of functional species in mesostructured materials with diverse transport properties

Mesostructured inorganic-organic hybrid materials have high interfacial areas, through-connecting mesoscale (2-50 nm) channels, and high mechanical and chemical robustnesses that can be exploited for diverse technological applications, especially those that involve the transport of charges, ions or molecules. These materials can, moreover, accommodate a broad assortment of functional molecular species that can mediate or instill transport properties. One interesting example is membrane proteins, which are biomacromolecules that transport ions or molecules across biological lipid bilayers at high rates and selectivities; for instance, the membrane protein proteorhodopsin actively transports H+-ions in response to light, which might be harnessed for solar-to-electrochemical energy conversion. Mesostructured inorganic-organic hybrid materials that include macroscopically aligned proteorhodopsin species are expected to generate bulk ion gradients across host materials under illumination. Here, a solution-based synthetic protocol is presented that allows high concentrations (up to 15 wt%) of active proteorhodopsin species to be incorporated within mesostructured silica membrane hosts. Synthesis conditions and compositions were selected to stabilize proteorhodopsin molecules in the presence of the structure-directing surfactant and soluble network-forming silica species that co-assemble to form mesostructured silica host matrices, as established by small-angle X-ray diffraction analyses. Multidimensional solid-state NMR spectra show that proteorhodopsin molecules incorporated within mesostructured silica hosts retain native-like structures, though with some interesting differences. The optical absorbance behaviors of proteorhodopsin guests in the synthetic mesostructured silica hosts correspond to the photochemical reaction cycles of proteorhodopsin in near-native environments that are associated with the active transport of H+-ions. The collective synthetic, structural and functional understanding developed here is leveraged to synthesize durable and optically transparent self-supporting mesostructured silica films that include high loadings of proteorhodopsin, as well as other membrane proteins. In separate mesostructured material systems, functional guest species at the mesostructure interfaces are shown to dramatically influence bulk material performances. Specifically, aminoalkyl-fullerene functionalities at the mesochannel surfaces of mesoporous silica can substantially modify the sorption and release behaviors of pharmaceutical species from these materials, while interfacial alkyl functionalities in polymer:fullerene heterojunctions can promote efficient separation of photo-generated charges

Ultra-enhanced spring branch growth in CO 2 -enriched trees: can it alter the phase of the atmosphere's seasonal CO 2 cycle?

Abstract Since the early 1960s, the declining phase of the atmosphere's seasonal CO 2 cycle has advanced by approximately 7 days in northern temperate latitudes, possibly as a result of increasing temperatures that may be advancing the time of occurrence of what may be called 'climatological spring.' However, just as several different phenomena are thought to have been responsible for the concomitant increase in the amplitude of the atmosphere's seasonal CO 2 oscillation, so too may other factors have played a role in bringing about the increasingly earlier spring drawdown of CO 2 that has resulted in the advancement of the declining phase of the air's CO 2 cycle. One of these factors may be the ongoing rise in the CO 2 content of the air itself; for the aerial fertilization effect of this phenomenon may be significantly enhancing the growth of each new season's initial flush of vegetation, which would tend to stimulate the early drawdown of atmospheric CO 2 and thereby advance the time of occurrence of what could be called 'biological spring.' Working with sour orange (Citrus aurantium L.) trees that have been growing out-of-doors in open-top chambers for over 10 years in air of either 400 or 700 ppm CO 2 , this hypothesis was investigated by periodically measuring the lengths, dry weights and leaf chlorophyll concentrations of new branches that emerged from the trees at the start of the 1998 growing season. The data demonstrate that the hypothesis is viable, and that it might possibly account for 2 of the 7 days by which the spring drawdown of the air's CO 2 concentration has advanced over the past few decades