Spectroscopy of canopy chemicals in humid tropical forests

Remote sensing of canopy chemistry could greatly advance the study and monitoring of functional processes and biological diversity in humid tropical forests. Imaging spectroscopy has contributed to canopy chemical remote sensing, but efforts to develop general, globally-applicable approaches have been limited by sparse and inconsistent field and laboratory data, and lacking analytical methods. We analyzed leaf hemispherical reflectance and transmittance spectra, along with a 21-chemical portfolio, taken from 6136 fully sunlit humid tropical forest canopies, and developed an up-scaling method using a combination of canopy radiative transfer, chemometric and high-frequency noise modeling. By integrating these steps, we found that the accuracy and precision of multi-chemical remote sensing of tropical forest canopies varies by leaf constituent and wavelength range. Under conditions of varying canopy structure and spectral noise, photosynthetic pigments, water, nitrogen, cellulose, lignin, phenols and leaf mass per area (LMA) are accurately estimated using visible-to-shortwave infrared spectroscopy (VSWIR; 400-2500 nm). Phosphorus and base cations are retrieved with lower yet significant accuracy. We also find that leaf chemical properties are estimated far more consistently, and with much higher precision and accuracy, using the VSWIR range rather than the more common and limited visible to near-infrared range (400-1050 nm; VNIR). While VNIR spectroscopy proved accurate for predicting foliar LMA, photosynthetic pigments and water, VSWIR spectra provided accurate estimates for three times the number of canopy traits. These global results proved to be independent of site conditions, taxonomic composition and phylogenetic history, and thus they should be broadly applicable to multi-chemical mapping of humid tropical forest canopies. The approach developed and tested here paves the way for studies of canopy chemical properties in humid tropical forests using the next generation of airborne and space-based high-fidelity imaging spectrometers.     

Comparison of interpolating methods for image resampling

When resampling an image to a new set of coordinates (for example, when rotating an image), there is often a noticeable loss in image quality. To preserve image quality, the interpolating function used for the resampling should be an ideal low-pass filter. To determine which limited extent convolving functions would provide the best interpolation, five functions were compared: A) nearest neighbor, B) linear, C) cubic B-spline, D) high-resolution cubic spline with edge enhancement (a = -1), and E) high-resolution cubic spline (a = -0.5). The functions which extend over four picture elements (C, D, E) were shown to have a better frequency response than those which extend over one (A) or two (B) pixels. The nearest neighbor function shifted the image up to one-half a pixel. Linear and cubic B-spline interpolation tended to smooth the image. The best response was obtained with the high-resolution cubic spline functions. The location of the resampled points with respect to the initial coordinate system has a dramatic effect on the response of the sampled interpolating function the data are exactly reproduced when the points are aligned, and the response has the most smoothing when the resampled points are equidistant from the original coordinate points. Thus, at the expense of some increase in computing time, image quality can be improved by resampled using the high-resolution cubic spline function as compared to the nearest neighbor, linear, or cubic B-spline functions.     

Lightweight component-based scalability

Digital libraries and information management systems are increasingly being developed according to component models with well-defined APIs and often with Web-accessible interfaces. In parallel with metadata access and harvesting, Web 2.0 mashups have demonstrated the flexibility of developing systems as independent distributed components. It can be argued that such distributed components also can be an enabler for scalability of service provision in medium to large systems. To test this premise, this article discusses how an existing component framework was modified to include support for scalability. A set of lightweight services and extensions were created to migrate and replicate services as the load changes. Experiments with the prototype system confirm that this system can in fact be quite effective as an enabler of transparent and efficient scalability, without the need to resort to complex middleware or substantial system reengineering. Finally, specific problems areas have been identified as future avenues for exploration at the crucial intersection of digital libraries and high-performance computing.     

Information on catalyst surface structure from crystallite morphologies observed by scanning electron microscopy (SEM)

The shapes of small crystals grown under equilibrium conditions are governed by the stabilities of their exposed faces. Computer simulation methods can be used to calculate surface energies and hence crystallite morphologies, illustrated by results for Cr₂O₃. Such calculations can include the effects of surface impurity segregation. Comparison of the resulting calculated crystal morphologies with those directly observed in the SEM thus provides a direct link between atomistic simulation and experiment.     

Homeless young people ‘strategizing’ a route to housing stability: service fatigue,exiting attempts and living ‘off grid’

Abstract

While access to housing has been identified as a crucial enabler to young people exiting homelessness, relatively little is known about the experiences of youth who encounter barriers in their attempts to secure housing. Mobilizing a pathways approach, this paper examines homeless young people’s experiences of seeking housing in a context of housing market forces that blocked their efforts to carve a route out of homelessness. The research, which is biographical and longitudinal, was conducted in Ireland between 2013 and 2016 and involved the collection of data at two points in time. At baseline, 40 young people aged 16–24 years and 10 of their family members were recruited (Phase 1) and, at the point of follow-up two years later (Phase 2), 74% of participants were retained in the study. By Phase 2, just 24% of the study’s young people were housed, pointing to significant barriers of access to housing. Moving beyond the identification of the impact of housing market forces on young people’s ability to exit homelessness, the analysis examines young people’s responses, focussing on the strategies used by them as they attempted to reclaim autonomy and control over their housing futures. Implications for the development of sustainable housing solutions that specifically cater to the needs of homeless youth are discussed.     

Toxic organics removal kinetics in overland flow land treatment

The efficiency in removing 13 trace organics from wastewater was studied on an outdoor, prototype overland flow land treatment system. More than 94% of each substance was removed at an application rate of 0.4 cm h⁻¹ (0.12 m³ h⁻¹ m⁻¹ of width). The % removals declined as application rates were increased. Removal from solution was described by first-order kinetics. A model based on the two-film theory was developed using three properties of each substance (the Henry's constant, the octanol-water partition coefficient and the molecular weight) and two system parameters (average water depth and residence time). The dependence of the removal process on temperature was consistent with the known dependence of Henry's constant and diffusivity on temperature. The model was tested on a second overland flow system.     

Low temperature synthesis of single crystalline ZnO nanorods by oblique angle deposition

The authors report the growth of single crystalline ZnO nanorods by direct current magnetron sputtering in the oblique angle deposition configuration near room temperature. These isolated nanorods have a diameter of  40 nm, an inter-rod spacing of  20 nm, and a height of  100 nm. The nanorods show a (002) orientation along the rod-axis which is normal to the substrate. The low temperature fabrication of single crystal ZnO nanorods may find potential applications in optoelectronics and energy conversion devices.     

People are people, but technology is not technology

Ubiquitous computing is about more than having multiple computers in our environment; it is also about computers venturing into completely new environments. In this paper, we examine the impact of computers in the developing world and look at why most interventions to date have failed to address the key needs of the users and their context. Through an analysis of existing software design techniques, and various case studies, we propose a new model for software creation, which we believe will address the issue of creating technologies for developing world nations.     

Functionalized TiO2 nanoparticles for use for in situ anion immobilization

Anatase particles (40-60 nm) were coated with an organosilane monolayer terminated with an ethylenediamine (EDA) ligand. These functionalized nanoparticles (FNPs) were then treated with an aqueous solution of Cu(II) to create a cationic Cu-EDA complex bound to the nanoparticle surface. Cu(II) and EDA ligand incorporation were confirmed by X-ray photoelectron spectroscopy (XPS) analysis. The Cu(EDA)2 FNP was then studied for its binding affinity for pertechnetate anion from a Hanford groundwater matrix. The Cu(EDA)2 FNP was also evaluated for its injectability into a porous medium for possible application as a subsurface semipermeable reactive barrier. Injection was readily accomplished, and resulted in a highly uniform distribution of the FNP sorbent in the test column.