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.

Integrated heterostructures of Group III-V nitride semiconductor materials including epitaxial ohmic contact, non-nitride buffer layer and methods of fabricating same

Abstract: An integrated heterostructure of Group III-V nitride compound semiconductors is formed on a multicomponent platform which includes a substrate of monocrystalline silicon carbide and a non-nitride buffer layer of monocrystalline zinc oxide. The zinc oxide may be formed by molecular beam epitaxy (MBE) using an MBE effusion cell containing zinc, and a source of atomic oxygen, such as an MBE-compatible oxygen plasma source which converts molecular oxygen into atomic oxygen. An ohmic contact for a semiconductor device formed of Group III-V nitride compound semiconductor materials including a layer of aluminum nitride or aluminum gallium nitride, includes a continuously graded layer of aluminum gallium nitride and a layer of gallium nitride or an alloy thereof on the continuously graded layer. The continuously graded layer eliminates conduction or valence band offsets. A multiple quantum well may also be used instead of the continuously graded layer where the thickness of the layers of gallium nitride increase across the multiple quantum well. The ohmic contacts may be used for Group III-V nitride laser diodes, light emitting diodes, electron emitters, bipolar transistors and field effect transistors.

Intergenerational Ties in Context: Grandparents Caring for Grandchildren in China

Abstract: Guided by theories and empirical research on intergenerational relationships, we examine the phenomenon of grandparents caring for grandchildren in contemporary China. Using a longitudinal dataset (China Health and Nutrition Survey), we document a high level of structural and functional solidarity in grandparent-grandchildren relationships. Intergenerational solidarity is indicated by a high rate of coresidence between grandchildren and grandparents, a sizable number of skipped-generation households (no parent present), extensive childcare involvement by non-coresidential grandparents, and a large amount of care provided by coresidential grandparents. Multivariate analysis further suggests that grandparents' childcare load is adaptive to familial needs, as reflected by the characteristics of the household, household members, and work activities of the mothers.

A Sparse Approximate Inverse Preconditioner for the Conjugate Gradient Method

Abstract: A method for computing a sparse incomplete factorization of the inverse of a symmetric positive definite matrix $A$ is developed, and the resulting factorized sparse approximate inverse is used as an explicit preconditioner for conjugate gradient calculations. It is proved that in exact arithmetic the preconditioner is well defined if $A$ is an H-matrix. The results of numerical experiments are presented.

Effects of Fat and NaCl/Phosphate Levels on the Chemical and Sensory Properties of Pork Patties

Abstract: Ground pork shoulders were combined with 50/50 pork trimmings to achieve fat levels of 20.0, 23.3, 26.6, and 30.0%. Salt/phosphate (NaCl/PO4) combinations of 0/0, 1/0, 1/0.25 and 2%/0.5% were blended with each fat level. Each treatment combination was stored at 3°C for 7 days in air-permeable film (AP), 21 days in vacuum pouches (VP) and at −23°C for 90 days in double-wrapped (DW) freezer paper. Fat level did not affect pH, expressed moisture (EM), peroxide value (PV), 2-thiobarbituric acid (TBA) values or cooking losses. Patties with 30.0% fat were jucier and required less energy to compress. A combination of 1%NaCl/0.25%PC4 reduced cooking losses, enhanced sensory properties and moderated the oxidation effects of NaCl up to 60 days of frozen storage. The NaCl treatment accelerated lipid oxidation most during all storage conditions while the control remained the least oxidized.

The early stages of duplicate gene evolution

Abstract: Gene duplications are one of the primary driving forces in the evolution of genomes and genetic systems. Gene duplicates account for 8–20% of the genes in eukaryotic genomes, and the rates of gene duplication are estimated at between 0.2% and 2% per gene per million years. Duplicate genes are believed to be a major mechanism for the establishment of new gene functions and the generation of evolutionary novelty, yet very little is known about the early stages of the evolution of duplicated gene pairs. It is unclear, for example, to what extent selection, rather than neutral genetic drift, drives the fixation and early evolution of duplicate loci. Analysis of recently duplicated genes in the Arabidopsis thaliana genome reveals significantly reduced species-wide levels of nucleotide polymorphisms in the progenitor and/or duplicate gene copies, suggesting that selective sweeps accompany the initial stages of the evolution of these duplicated gene pairs. Our results support recent theoretical work that indicates that fates of duplicate gene pairs may be determined in the initial phases of duplicate gene evolution and that positive selection plays a prominent role in the evolutionary dynamics of the very early histories of duplicate nuclear genes.