North Carolina State University

About: North Carolina State University is a education organization based out in Raleigh, North Carolina, United States. It is known for research contribution in the topics: Population & Thin film. The organization has 44161 authors who have published 101744 publications receiving 3456774 citations. The organization is also known as: NCSU & North Carolina State University at Raleigh.

Fragmentation of Continental United States Forests

Abstract: We report a multiple-scale analysis of forest fragmentation based on 30-m (0.09 ha pixel 1 ) landcover maps for the conterminous United States. Each 0.09-ha unit of forest was classified according to fragmentation indexes measured within the surrounding landscape, for five landscape sizes including 2.25, 7.29, 65.61, 590.49, and 5314.41 ha. Most forest is found in fragmented landscapes. With 65.61-ha landscapes, for example, only 9.9% of all forest was contained in a fully forested landscape, and only 46.9% was in a landscape that was more than 90% forested. Overall, 43.5% of forest was located within 90 m of forest edge and 61.8% of forest was located within 150 m of forest edge. Nevertheless, where forest existed, it was usually dominant—at least 72.9% of all forest was in landscapes that were at least 60% forested for all landscape sizes. Small (less than 7.29 ha) perforations in otherwise continuous forest cover accounted for about half of the fragmentation. These results suggest that forests are connected over large regions, but fragmentation is so pervasive that edge effects potentially influence ecological processes on most forested lands.

Soil microbial responses to experimental warming and clipping in a tallgrass prairie.

Abstract: Global surface temperature is predicted to increase by 1.4–5.8°C by the end of this century. However, the impacts of this projected warming on soil C balance and the C budget of terrestrial ecosystems are not clear. One major source of uncertainty stems from warming effects on soil microbes, which exert a dominant influence on the net C balance of terrestrial ecosystems by controlling organic matter decomposition and plant nutrient availability. We, therefore, conducted an experiment in a tallgrass prairie ecosystem at the Great Plain Apiaries (near Norman, OK) to study soil microbial responses to temperature elevation of about 2°C through artificial heating in clipped and unclipped field plots. While warming did not induce significant changes in net N mineralization, soil microbial biomass and respiration rate, it tended to reduce extractable inorganic N during the second and third warming years, likely through increasing plant uptake. In addition, microbial substrate utilization patterns and the profiles of microbial phospholipid fatty acids (PLFAs) showed that warming caused a shift in the soil microbial community structure in unclipped subplots, leading to the relative dominance of fungi as evidenced by the increased ratio of fungal to bacterial PLFAs. However, no warming effect on soil microbial community structure was found in clipped subplots where a similar scale of temperature increase occurred. Clipping also significantly reduced soil microbial biomass and respiration rate in both warmed and unwarmed plots. These results indicated that warming-led enhancement of plant growth rather than the temperature increase itself may primarily regulate soil microbial response. Our observations show that warming may increase the relative contribution of fungi to the soil microbial community, suggesting that shifts in the microbial community structure may constitute a major mechanism underlying warming acclimatization of soil respiration.

Generation of Synthetic Elastin-Mimetic Small Diameter Fibers and Fiber Networks

Abstract: Elastin-mimetic peptide polymers have been synthesized, and the morphological properties of fabricated small diameter fibers and nonwoven fabrics have been characterized. An 81 kDa recombinant protein based upon the repeating elastomeric peptide sequence of elastin (Val-Pro-Gly-Val-Gly)4(Val-Pro-Gly-Lys-Gly) was obtained through bacterial expression of an oligomerized gene coding for tandem repeats of the monomer. The protein was processed into fibers by an electrospinning technique and morphology defined by SEM and TEM. The choice of processing parameters influenced both fiber diameter and morphology with diameters varying between 200 and 3000 nm and three morphological patterns noted: beaded fibers, thin filaments, and broad ribbonlike structures. Detailed image analysis of nonwoven textile fabrics produced from elastin-mimetic fibers revealed that the distribution of single fiber orientation was isotropic with an associated unimodal distribution of protein fiber diameter. In a dry state, the ultimate ...

Aggregate Query Answering on Anonymized Tables

Abstract: Privacy is a serious concern when microdata need to be released for ad hoc analyses. The privacy goals of existing privacy protection approaches (e.g., k-anonymity and l-diversity) are suitable only for categorical sensitive attributes. Since applying them directly to numerical sensitive attributes (e.g., salary) may result in undesirable information leakage, we propose privacy goals to better capture the need of privacy protection for numerical sensitive attributes. Complementing the desire for privacy is the need to support ad hoc aggregate analyses over microdata. Existing generalization-based anonymization approaches cannot answer aggregate queries with reasonable accuracy. We present a general framework of permutation-based anonymization to support accurate answering of aggregate queries and show that, for the same grouping, permutation-based techniques can always answer aggregate queries more accurately than generalization-based approaches. We further propose several criteria to optimize permutations for accurate answering of aggregate queries, and develop efficient algorithms for each criterion.

Effects of the nearest neighbors and the alloy matrix on SiH stretching vibrations in the amorphous SiO r :H (0<r<2) alloy system

Abstract: Hydrogenated silicon suboxides, ${\mathrm{SiO}}_{\mathrm{r}}$:H, for alloy range (0lrl2) have been deposited by remote plasma-enhanced chemical vapor deposition (remote PECVD) under conditions in which hydrogen is incorporated predominantly in monohydride or SiH bonding configurations. We have investigated both the SiH bond-stretching and bond-bending absorption bands by infrared (ir) absorption spectroscopy as a function of r, the alloy composition. In this paper, we have focused on the bond-stretching absorption bands, and have modeled the shape of the bond-stretching band as a function of the alloy composition. There are four distinct local environments for the SiH group in the sub- oxides; these can be written as HSi-${\mathrm{Si}}_{3\mathrm{\ensuremath{-}}\mathrm{n}}$${\mathrm{O}}_{\mathrm{n}}$, for n=0--3. A sum of Gaussian functions, one for each environment, is used to synthesize the absorption in the SiH stretching band. The peak positions of these Gaussians are calculated by an induction model which includes both local and matrix (or alloy) effects; the amplitude weightings are determined from a random statistical model for the local bonding environments of the Si-O groups in the ${\mathrm{SiO}}_{\mathrm{r}}$ alloy. We find that the frequency shifts caused by changes in the matrix, and associated with different values of r, are comparable to the shifts associated with the different local environments. The combination of these effects serves to diminish the discreteness of subband features in the absorption spectrum.