Effects of woody elements on simulated canopy reflectance: Implications for forest chlorophyll content retrieval

An important bio-indicator of actual plant health status, the foliar content of chlorophyll a and b (Cab), can be estimated using imaging spectroscopy. For forest canopies, however, the relationship between the spectral response and leaf chemistry is confounded by factors such as background (e.g. understory), canopy structure, and the presence of non-photosynthetic vegetation (NPV, e.g. woody elements)—particularly the appreciable amounts of standing and fallen dead wood found in older forests. We present a sensitivity analysis for the estimation of chlorophyll content in woody coniferous canopies using radiative transfer modeling, and use the modeled top-of-canopy reflectance data to analyze the contribution of woody elements, leaf area index (LAI), and crown cover (CC) to the retrieval of foliar Cab content. The radiative transfer model used comprises two linked submodels: one at leaf level (PROSPECT) and one at canopy level (FLIGHT). This generated bidirectional reflectance data according to the band settings of the Compact High Resolution Imaging Spectrometer (CHRIS) from which chlorophyll indices were calculated. Most of the chlorophyll indices outperformed single wavelengths in predicting Cab content at canopy level, with best results obtained by the Maccioni index ([R₇₈₀ − R₇₁₀] / [R₇₈₀ − R₆₈₀]). We demonstrate the performance of this index with respect to structural information on three distinct coniferous forest types (young, early mature and old-growth stands). The modeling results suggest that the spectral variation due to variation in canopy chlorophyll content is best captured for stands with medium dense canopies. However, the strength of the up-scaled Cab signal weakens with increasing crown NPV scattering elements, especially when crown cover exceeds 30%. LAI exerts the least perturbations. We conclude that the spectral influence of woody elements is an important variable that should be considered in radiative transfer approaches when retrieving foliar pigment estimates in heterogeneous stands, particularly if the stands are partly defoliated or long-lived.     

Regio‐ and Enantioselective Sequential Dehalogenation of rac‐1,3‐Dibromobutane by Haloalkane Dehalogenase LinB

The hydrolytic dehalogenation of rac‐1,3‐dibromobutane catalyzed by the haloalkane dehalogenase LinB from Sphingobium japonicum UT26 proceeds in a sequential fashion: initial formation of intermediate haloalcohols followed by a second hydrolytic step to produce the final diol. Detailed investigation of the course of the reaction revealed favored nucleophilic displacement of the sec‐halogen in the first hydrolytic event with pronounced R enantioselectivity. The second hydrolysis step proceeded with a regioselectivity switch at the primary position, with preference for the S enantiomer. Because of complex competition between all eight possible reactions, intermediate haloalcohols formed with moderate to good ee ((S)‐4‐bromobutan‐2‐ol: up to 87 %). Similarly, (S)‐butane‐1,3‐diol was formed at a maximum ee of 35 % before full hydrolysis furnished the racemic diol product.     

Approximating curves and their offsets using biarcs and Pythagorean hodograph quintics

This paper compares two techniques for the approximation of the offsets to a given planar curve. The two methods are based on approximate conversion of the planar curve into circular splines and Pythagorean hodograph (PH) splines, respectively. The circular splines are obtained using a novel variant of biarc interpolation, while the PH splines are constructed via Hermite interpolation of C¹ boundary data.We analyze the approximation order of both conversion procedures. As a new result, the C¹ Hermite interpolation with PH quintics is shown to have approximation order 4 with respect to the original curve, and 3 with respect to its offsets. In addition, we study the resulting data volume, both for the original curve and for its offsets. It is shown that PH splines outperform the circular splines for increasing accuracy, due to the higher approximation order.     

The comprehensive in vitro evaluation of eight different calcium phosphates: Significant parameters for cell behavior

Eight different calcium phosphate nanoparticles, namely bovine bone bioapatite calcined at 500, 600, and 700°C, Mg-doped brushite, fluorinated calcium phosphate, Ca-deficient hydroxyapatite, hydroxyapatite, and tricalcium phosphate, were characterized employing physico-chemical methods. Their cytocompatibility was evaluated under human osteoblast-like cell line MG-63 culture conditions in elution media and via the direct interaction of cells with calcium phosphate nanoparticles. The main objective was to determine the correlation of the cell indices with the differently determined physical and chemical parameters of the calcium phosphates. Chemical composition, which contributes toward pH changes, and the calcium ion concentration in the medium appear to make up particularly significant factors; moreover, it was proved that the number of material types represents a further important aspect. In the case of a large number of material types, almost no correlation was determined between the analyzed parameters; however, in the case of a small number of apatite types, several positive correlations were found. It can be concluded that it is not possible to identify any monitored parameters that had a major impact on cell behavior or, at least, such an effect which can be generalized. It appears more likely that cell behavior is affected by the interplay of various parameters.     

Quantification of microvessels in canine lymph nodes

Quantification of microvessels in tumors is mostly based on counts of vessel profiles in tumor hot spots. Drawbacks of this method include low reproducibility and large interobserver variance, mainly as a result of individual differences in sampling of image fields for analysis. Our aim was to test an unbiased method for quantifying microvessels in healthy and tumorous lymph nodes of dogs. The endothelium of blood vessels was detected in paraffin sections by a combination of immunohistochemistry (von Willebrand factor) and lectin histochemistry (wheat germ agglutinin) in comparison with detection of basal laminae by laminin immunohistochemistry or silver impregnation. Systematic uniform random sampling of 50 image fields was performed during photo-documentation. An unbiased counting frame (area 113,600 microm(2)) was applied to each micrograph. The total area sampled from each node was 5.68 mm(2). Vessel profiles were counted according to stereological counting rules. Inter- and intraobserver variabilities were tested. The application of systematic uniform random sampling was compared with the counting of vessel profiles in hot spots. The unbiased estimate of the number of vessel profiles per unit area ranged from 100.5 +/- 44.0/mm(2) to 442.6 +/- 102.5/mm(2) in contrast to 264 +/- 72.2/mm(2) to 771.0 +/- 108.2/mm(2) in hot spots. The advantage of using systematic uniform random sampling is its reproducibility, with reasonable interobserver and low intraobserver variance. This method also allows for the possibility of using archival material, because staining quality is not limiting as it is for image analysis, and artifacts can easily be excluded. However, this method is comparatively time-consuming.     

Potential biomarkers for early detection of acute graft-versus-host disease

Acute graft-versus-host disease (aGVHD) is the main complication of allogeneic hematopoietic stem cell transplantation (HCT), resulting in considerable morbidity and mortality. Currently, the diagnosis of aGVHD is largely made based on clinical parameters and invasive biopsies. For the past 20 years, researchers have been trying to find reliable biomarkers to enable early and accurate diagnosis of aGVHD. Although a number of potential aGVHD biomarkers have been published, as yet, no validated diagnostic test is available. Proteomics encompasses a broad range of rapidly developing technologies, which have shown tremendous promise for early detection of aGVHD. In this article, we review the current state of aGVHD biomarker discovery, provide a summary of the key proteins of interest and the most common analytical procedures for the clinic, as well as outlining the significant challenges faced in their use.     

Rational Pythagorean-hodograph space curves

A method for constructing rational Pythagorean-hodograph (PH) curves in R³ is proposed, based on prescribing a field of rational unit tangent vectors. This tangent field, together with its first derivative, defines the orientation of the curve osculating planes. Augmenting this orientation information with a rational support function, that specifies the distance of each osculating plane from the origin, then completely defines a one-parameter family of osculating planes, whose envelope is a developable ruled surface. The rational PH space curve is identified as the edge of regression (or cuspidal edge) of this developable surface. Such curves have rational parametric speed, and also rational adapted frames that satisfy the same conditions as polynomial PH curves in order to be rotation-minimizing with respect to the tangent. The key properties of such rational PH space curves are derived and illustrated by examples, and simple algorithms for their practical construction by geometric Hermite interpolation are also proposed.     

Properties of high performance concrete containing fine-ground ceramics as supplementary cementitious material

This paper presents experimental work regarding the basic physical characteristics, mechanical and fracture-mechanics properties, durability characteristics, hydric and thermal properties of high performance concrete (HPC) with up to 60% of Portland cement replaced by fine-ground ceramics. Experimental results show that the amount of the ceramics in the mix is limited mainly by the resistance against de-icing salts which is found satisfactory only up to the cement replacement level of 10%. The mechanical and water transport properties are not significantly impaired by ceramic additions of up to 20%, whereas the effective fracture toughness, specific fracture energy, and chemical resistance (to MgCl₂, NH₄Cl, Na₂SO₄, HCl) are effectively maintained up to 40%. The frost resistance, water vapor transport and storage parameters and thermal properties are not significantly impaired even up to a 60% replacement level.     

Heterogeneous ion-selective membranes: the influence of the inert matrix polymer on the membrane properties

Heterogeneous ion-exchange membranes were prepared by mixing small particles of sulfonated poly(1,4-phenylene sulfide) or sulfonated styrene–divinylbenzene copolymer with a matrix polymer. Four kinds of polymers were tested as a matrix: highly flexible linear polyethylene, medium-flexible fluoroelastomer, rigid polystyrene (all highly hydrophobic) and hydrophilic cellulose prepared by hydrolysis of cellulose acetate butyrate. Membrane morphologies were studied by scanning electron microscopy, IR spectroscopy and density measurements. Subsequently, the membranes were characterised with respect to their swelling in water, electrochemical characteristics and transport properties. Ion-exchange capacity and proton conductivity together with the permeability to hydrogen and methanol were investigated. The important impact of the ion-exchange particles as well as of the polymer matrix used was observed. The increasing rigidity of the polymer matrix resulted in a decrease in membrane permeability, but at the same time in deterioration of its ion-exchange capacity and subsequently of the proton conductivity, too. This was explained in terms of the limited elasticity of the polymer matrix, in each sample under study, which does not allow the ion-exchange particles to swell to an identical degree.     

High performance concrete containing lower slag amount: A complex view of mechanical and durability properties

A wide set of parameters of concrete containing 10% of ground granulated blast furnace slag as Portland cement replacement involving basic material characteristics, mechanical and fracture-mechanical properties, durability characteristics, hydric and thermal properties and chloride binding characteristics is determined and compared with the parameters of reference Portland cement concrete with otherwise the same composition. The experimental results show that the replacement of Portland cement by even such a low amount of ground granulated blast furnace slag as environmental more friendly and still valuable alternative binder either affects positively or at least does not worsen in a significant way the substantial properties of hardened concrete mix. The mechanical and fracture-mechanical properties are found to be very similar as compared to the reference mix, the liquid water transport parameters of the mix containing slag are significantly better, the basic durability characteristics such as the frost resistance and corrosion resistance similar and very good, the resistance against de-icing salts slightly worse. These findings may be significant for the future use of slag in the countries where its available amount is decreasing and its more efficient use as a binder than it was common to date can appear necessary.