A Case Study on the Impacts of Rigor, Relevance, and Relationships in a Freshman Academy for Secondary Classroom Students

This study researched the impact a Freshman Academy approach has on rigor, relevance, and relationships in a secondary classroom setting. For the purpose of this paper, a Freshman Academy is one where ninth-grade students are grouped together in their core academic courses with a common group of teachers. Within these common academic courses, ideas and concepts are integrated in order to transition more effectively into the high school environment and provide students with a more cohesive academic experience. This paper further reflects the current, critical problems in existence in today’s high school setting that can potentially be addressed using the Freshman Academy approach. Therefore, the purpose of this study was to examine how integrating the curriculum, utilizing effective teacher collaboration, and creating a Freshman Academy impact the rigor, relevance, and relationships for both students and teachers during the ninth-grade year

Performance of tropical maize hybrids under conditions of low and optimum levels of nitrogen fertilizer application grain yield, biomass production and nitrogen accumulation

Nitrogen (N) is the most limiting mineral nutrient in the soils of the major maize producing areas of West and Central Africa. Low soil N and sub-optimal application of N fertilizers lead to N deficiency and poor grain yield (GY) in maize. Maize varieties with improved grain yield under low soil N and increased performance under optimal N availability could be beneficial to low input agriculture. This study evaluated the performance of a selection of experimental and commercial hybrids under suboptimal and optimal N fertilizer applications. Significant differences were observed among the hybrids, as well as significant interactions between hybrid and N level for GY and other measured attributes, with the severity of variation increasing as the level of N decreases. Mean GY reductions across the years was 76.5% at no-N and 35.4% at low-N. Depending on N treatment, GY varied from 0.48 to 4.42 Mg ha-1, grain N content from 0.17 to 1.26 g plant-1, total N content at harvest from 0.33 to 2.00 g plant-1, above ground biomass at silking from 30.6 to 91.2 g plant-1 and at maturity from 39.9 to 191.1 g plant-1. Number of kernels was the GY component most severely reduced by N stress and had significant (p = 0.001) positive correlation with GY at all N levels. Six hybrids (4001/4008, KU1409/4008, KU1409/9613, 4008/1808, 4058/Fun 47-4, and 1824/9432) which showed consistent above average grain yields under no-N, low-N, high-N and across N levels were found and their use could further be investigated

Genomic and small RNA sequencing of Miscanthus × giganteus shows the utility of sorghum as a reference genome sequence for Andropogoneae grasses

Genomic data together with sequencing of tissue specific small RNA libraries reveals insights into the genome content, small RNA repertoire and evolutionary origins of the grass Miscanthus × giganteus

A framework genetic map for Miscanthus sinensis from RNAseq-based markers shows recent tetraploidy

Abstract Background Miscanthus (subtribe Saccharinae, tribe Andropogoneae, family Poaceae) is a genus of temperate perennial C4 grasses whose high biomass production makes it, along with its close relatives sugarcane and sorghum, attractive as a biofuel feedstock. The base chromosome number of Miscanthus (x = 19) is different from that of other Saccharinae and approximately twice that of the related Sorghum bicolor (x = 10), suggesting large-scale duplications may have occurred in recent ancestors of Miscanthus. Owing to the complexity of the Miscanthus genome and the complications of self-incompatibility, a complete genetic map with a high density of markers has not yet been developed. Results We used deep transcriptome sequencing (RNAseq) from two M. sinensis accessions to define 1536 single nucleotide variants (SNVs) for a GoldenGate™ genotyping array, and found that simple sequence repeat (SSR) markers defined in sugarcane are often informative in M. sinensis. A total of 658 SNP and 210 SSR markers were validated via segregation in a full sibling F1 mapping population. Using 221 progeny from this mapping population, we constructed a genetic map for M. sinensis that resolves into 19 linkage groups, the haploid chromosome number expected from cytological evidence. Comparative genomic analysis documents a genome-wide duplication in Miscanthus relative to Sorghum bicolor, with subsequent insertional fusion of a pair of chromosomes. The utility of the map is confirmed by the identification of two paralogous C4-pyruvate, phosphate dikinase (C4-PPDK) loci in Miscanthus, at positions syntenic to the single orthologous gene in Sorghum. Conclusions The genus Miscanthus experienced an ancestral tetraploidy and chromosome fusion prior to its diversification, but after its divergence from the closely related sugarcane clade. The recent timing of this tetraploidy complicates discovery and mapping of genetic markers for Miscanthus species, since alleles and fixed differences between paralogs are comparable. These difficulties can be overcome by careful analysis of segregation patterns in a mapping population and genotyping of doubled haploids. The genetic map for Miscanthus will be useful in biological discovery and breeding efforts to improve this emerging biofuel crop, and also provide a valuable resource for understanding genomic responses to tetraploidy and chromosome fusion

A framework genetic map for \u3ci\u3eMiscanthus sinensis\u3c/i\u3e from RNAseq-based markers shows recent tetraploidy

Background: Miscanthus (subtribe Saccharinae, tribe Andropogoneae, family Poaceae) is a genus of temperate perennial C4 grasses whose high biomass production makes it, along with its close relatives sugarcane and sorghum, attractive as a biofuel feedstock. The base chromosome number of Miscanthus (x = 19) is different from that of other Saccharinae and approximately twice that of the related Sorghum bicolor (x = 10), suggesting largescale duplications may have occurred in recent ancestors of Miscanthus. Owing to the complexity of the Miscanthus genome and the complications of self-incompatibility, a complete genetic map with a high density of markers has not yet been developed. Results: We used deep transcriptome sequencing (RNAseq) from two M. sinensis accessions to define 1536 single nucleotide variants (SNVs) for a GoldenGate™ genotyping array, and found that simple sequence repeat (SSR) markers defined in sugarcane are often informative in M. sinensis. A total of 658 SNP and 210 SSR markers were validated via segregation in a full sibling F1 mapping population. Using 221 progeny from this mapping population, we constructed a genetic map for M. sinensis that resolves into 19 linkage groups, the haploid chromosome number expected from cytological evidence. Comparative genomic analysis documents a genomewide duplication in Miscanthus relative to Sorghum bicolor, with subsequent insertional fusion of a pair of chromosomes. The utility of the map is confirmed by the identification of two paralogous C4-pyruvate, phosphate dikinase (C4-PPDK) loci in Miscanthus, at positions syntenic to the single orthologous gene in Sorghum. Conclusions: The genus Miscanthus experienced an ancestral tetraploidy and chromosome fusion prior to its diversification, but after its divergence from the closely related sugarcane clade. The recent timing of this tetraploidy complicates discovery and mapping of genetic markers for Miscanthus species, since alleles and fixed differences between paralogs are comparable. These difficulties can be overcome by careful analysis of segregation patterns in a mapping population and genotyping of doubled haploids. The genetic map for Miscanthus will be useful in biological discovery and breeding efforts to improve this emerging biofuel crop, and also provide a valuable resource for understanding genomic responses to tetraploidy and chromosome fusion

Influence of Fabrication Technique on the Fiber Pushout Behavior in a Sapphire-Reinforced Nial Matrix Composite

Directional solidification (DS) of \u27\u27powder-cloth\u27\u27 (PC) processed sapphire-NiAl composites was carried out to examine the influence of fabrication technique on the fiber-matrix interfacial shear strength, measured using a fiber-pushout technique. The DS process replaced the fine, equiaxed NiAl grain structure of the PC composites with an oriented grain structure comprised of large columnar NiAl grains aligned parallel to the fiber axis, with fibers either completely engulfed within the NiAl grains or anchored at one to three grain boundaries. The load-displacement behavior during the pushout test exhibited an initial \u27\u27pseudoelastic\u27\u27 response, followed by an \u27\u27inelastic\u27\u27 response, and finally a \u27\u27frictional\u27\u27 sliding response. The fiber-matrix interfacial shear strength and the fracture behavior during fiber pushout were investigated using an interrupted pushout test and fractography, as functions of specimen thickness (240 to 730 mu m) and fabrication technique. The composites fabricated using the PC and the DS techniques had different matrix and interface structures and appreciably different interfacial shear strengths. In the DS composites, where the fiber-matrix interfaces were identical for all the fibers, the interfacial debond shear stresses were larger for the fibers embedded completely within the NiAl grains and smaller for the fibers anchored at a few grain boundaries. The matrix grain boundaries coincident on sapphire fibers were observed to be the preferred sites for crack formation and propagation. While the frictional sliding stress appeared to be independent of the fabrication technique, the interfacial debond shear stresses were larger for the DS composites compared to the PC composites. The study highlights the potential of the DS technique to grow single-crystal NiAl matrix composites reinforced with sapphire fibers, with fiber-matrix interfacial shear strength appreciably greater than that attainable by the current solid-state fabrication techniques

Microcollinearity between autopolyploid sugarcane and diploid sorghum genomes

Abstract\ud \ud \ud \ud Background\ud \ud Sugarcane (Saccharum spp.) has become an increasingly important crop for its leading role in biofuel production. The high sugar content species S. officinarum is an octoploid without known diploid or tetraploid progenitors. Commercial sugarcane cultivars are hybrids between S. officinarum and wild species S. spontaneum with ploidy at ~12×. The complex autopolyploid sugarcane genome has not been characterized at the DNA sequence level.\ud \ud \ud \ud Results\ud \ud The microsynteny between sugarcane and sorghum was assessed by comparing 454 pyrosequences of 20 sugarcane bacterial artificial chromosomes (BACs) with sorghum sequences. These 20 BACs were selected by hybridization of 1961 single copy sorghum overgo probes to the sugarcane BAC library with one sugarcane BAC corresponding to each of the 20 sorghum chromosome arms. The genic regions of the sugarcane BACs shared an average of 95.2% sequence identity with sorghum, and the sorghum genome was used as a template to order sequence contigs covering 78.2% of the 20 BAC sequences. About 53.1% of the sugarcane BAC sequences are aligned with sorghum sequence. The unaligned regions contain non-coding and repetitive sequences. Within the aligned sequences, 209 genes were annotated in sugarcane and 202 in sorghum. Seventeen genes appeared to be sugarcane-specific and all validated by sugarcane ESTs, while 12 appeared sorghum-specific but only one validated by sorghum ESTs. Twelve of the 17 sugarcane-specific genes have no match in the non-redundant protein database in GenBank, perhaps encoding proteins for sugarcane-specific processes. The sorghum orthologous regions appeared to have expanded relative to sugarcane, mostly by the increase of retrotransposons.\ud \ud \ud \ud Conclusions\ud \ud The sugarcane and sorghum genomes are mostly collinear in the genic regions, and the sorghum genome can be used as a template for assembling much of the genic DNA of the autopolyploid sugarcane genome. The comparable gene density between sugarcane BACs and corresponding sorghum sequences defied the notion that polyploidy species might have faster pace of gene loss due to the redundancy of multiple alleles at each locus.We acknowledge our colleagues at the University of Oklahomas Advanced Center for Genome Technology, Chunmei Qu and Ping Wang for their assistance with 454 GSFLX sequencing sample preparation and Steve Kenton for his help with deconvoluting the pooled BACs and their subsequent assembly. We also thank Eric Tang for assistance on sequencing two BACs using Sanger sequencers. This project is supported by startup funds from the University of Illinois to RM and a grant from the Energy Bioscience Institute (EBI) to SPM, MEH, RM, and DSR.We acknowledge our colleagues at the University of Oklahoma's Advanced Center for Genome Technology, Chunmei Qu and Ping Wang for their assistance with 454 GS-FLX sequencing sample preparation and Steve Kenton for his help with deconvoluting the pooled BACs and their subsequent assembly. We also thank Eric Tang for assistance on sequencing two BACs using Sanger sequencers. This project is supported by start-up funds from the University of Illinois to RM and a grant from the Energy Bioscience Institute (EBI) to SPM, MEH, RM, and DSR

The Genomic Signature of Crop-Wild Introgression in Maize

The evolutionary significance of hybridization and subsequent introgression has long been appreciated, but evaluation of the genome-wide effects of these phenomena has only recently become possible. Crop-wild study systems represent ideal opportunities to examine evolution through hybridization. For example, maize and the conspecific wild teosinte Zea mays ssp. mexicana, (hereafter, mexicana) are known to hybridize in the fields of highland Mexico. Despite widespread evidence of gene flow, maize and mexicana maintain distinct morphologies and have done so in sympatry for thousands of years. Neither the genomic extent nor the evolutionary importance of introgression between these taxa is understood. In this study we assessed patterns of genome-wide introgression based on 39,029 single nucleotide polymorphisms genotyped in 189 individuals from nine sympatric maize-mexicana populations and reference allopatric populations. While portions of the maize and mexicana genomes were particularly resistant to introgression (notably near known cross-incompatibility and domestication loci), we detected widespread evidence for introgression in both directions of gene flow. Through further characterization of these regions and preliminary growth chamber experiments, we found evidence suggestive of the incorporation of adaptive mexicana alleles into maize during its expansion to the highlands of central Mexico. In contrast, very little evidence was found for adaptive introgression from maize to mexicana. The methods we have applied here can be replicated widely, and such analyses have the potential to greatly informing our understanding of evolution through introgressive hybridization. Crop species, due to their exceptional genomic resources and frequent histories of spread into sympatry with relatives, should be particularly influential in these studies

Iterative joint frequency offset and channel estimation for OFDM systems using first and second order approximation algorithms

[[abstract]]To implement an algorithm for joint estimation of carrier frequency offset (CFO) and channel impulse response (CIR) in orthogonal frequency division multiplexing (OFDM) systems, the maximum-likelihood criterion is commonly adopted. A major difficulty arises from the highly nonlinear nature of the log-likelihood function which renders local extrema or multiple solutions for the CFO and CIR estimators. Use of an approximation method coupled with an adaptive iteration algorithm has been a popular approach to ease problem solving. The approximation used in those existing methods is usually of the first order level. Here, in addition to a new first order approximation method, we also propose a second order approximation method. Further, for the part of the adaptive iteration algorithm, we adopt a new technique which will enable performance improvement. Our first order approximation method is found to outperform the existing ones in terms of estimation accuracies, tracking range, computation complexity, and convergence speed. As expected, our second order approximation method provides an even further improvement at the expense of higher computation complication.[[notice]]補正完畢[[journaltype]]國外[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子版[[countrycodes]]DE

Bin mapping of tomato diversity array (DArT) markers to genomic regions of Solanum lycopersicum × Solanum pennellii introgression lines

Marker-trait association studies in tomato have progressed rapidly due to the availability of several populations developed between wild species and domesticated tomato. However, in the absence of whole genome sequences for each wild species, molecular marker methods for whole genome comparisons and fine mapping are required. We describe the development and validation of a diversity arrays technology (DArT) platform for tomato using an introgression line (IL) population consisting of wild Solanumpennellii introgressed into Solanumlycopersicum (cv. M82). A tomato diversity array consisting of 6,912 clones from domesticated tomato and twelve wild tomato/Solanaceous species was constructed. We successfully bin-mapped 990 polymorphic DArT markers together with 108 RFLP markers across the IL population, increasing the number of markers available for each S.pennellii introgression by tenfold on average. A subset of DArT markers from ILs previously associated with increased levels of lycopene and carotene were sequenced, and 44% matched protein coding genes. The bin-map position and order of sequenced DArT markers correlated well with their physical position on scaffolds of the draft tomato genome sequence (SL2.40). The utility of sequenced DArT markers was illustrated by converting several markers in both the S.pennellii and S.lycopersicum phases to cleaved amplified polymorphic sequence (CAPS) markers. Genotype scores from the CAPS markers confirmed the genotype scores from the DArT hybridizations used to construct the bin map. The tomato diversity array provides additional “sequence-characterized” markers for fine mapping of QTLs in S.pennellii ILs and wild tomato species