631 research outputs found
The Information Content of the NCREIF Index
This paper examines the dynamic behavior of the NCREIF index. NCREIF total return and appreciation indexes are smooth and exhibit strong autocorrelation and autoregressive heteroskedasticity. We test the information transmission from the NAREIT index to the NCREIF index. In our VAR analysis, the NAREIT index returns Granger cause the returns of the NCREIF indexes. In our ARCH information transmission analysis, the NCREIF indexes are observed to incorporate information spillover from the NAREIT indexes in both the mean and variance of the index returns. The ARCH dynamics between the NCREIF and NAREIT indexes suggest a nonlinear relation between the two indexes.
Near-Duplicate Image Retrieval Based on Contextual Descriptor
The state of the art of technology for near-duplicate image retrieval is mostly based on the Bag-of-Visual-Words model. However, visual words are easy to result in mismatches because of quantization errors of the local features the words represent. In order to improve the precision of visual words matching, contextual descriptors are designed to strengthen their discriminative power and measure the contextual similarity of visual words. This paper presents a new contextual descriptor that measures the contextual similarity of visual words to immediately discard the mismatches and reduce the count of candidate images. The new contextual descriptor encodes the relationships of dominant orientation and spatial position between the referential visual words and their context. Experimental results on benchmark Copydays dataset demonstrate its efficiency and effectiveness for near-duplicate image retrieval
Genome-wide association studies to dissect the genetic architecture of yield-related traits in maize and the genetic basis of heterosis
This dissertation includes a general introduction (Chapter 1), three journal manuscripts (Chapters 2 to 4) and a section of general conclusions (Chapter 5). The paper in Chapter 2, which compares three statistical approaches for conducting GWAS and identifies the genetic architecture controlling for KRN trait, has been submitted for publication. I made major contributions include designing and performing the experiments, analyzing data and writing the manuscript under the guidance of Dr. Schnable. Dr. Nettleton and Dr. Dekkers provided technical support and conceptual advice for this work. The paper in Chapter 3, which investigates the modes of inheritance of trait-associated variants for seven yield-related traits and provides insight into heterosis, will soon be submitted for publication. I made major contributions to this experiment that include designing the experiments, supervising the data collection, data investigations, and writing the manuscript under the guidance of Dr. Schnable. Dr. Nettleton provided technical support and conceptual advice for this work. The paper in Chapter 4 reports a new method (termed XP-GWAS,) that uses pools of extreme-phenotype for conducting GWAS, will also be submitted for publication. My contributions to this paper include developing the concept, designing experiments, analyzing data and writing the manuscripts under the guidance of Dr. Schnable. The co-first author, Haiying Jiang assisted with data collection. Dr. Nettleton advised on the data analysis and wrote some custom R scripts for the data analysis
Optimising the identification of causal variants across varying genetic architectures in crops
Association studies use statistical links between genetic markers and the phenotype variation across many individuals to identify genes controlling variation in the target phenotype. However, this approach, particularly conducted on a genome-wide scale (GWAS), has limited power to identify the genes responsible for variation in traits controlled by complex genetic architectures. In this study, we employ real-world genotype datasets from four crop species with distinct minor allele frequency distributions, population structures and linkage disequilibrium patterns. We demonstrate that different GWAS statistical approaches provide favourable trade-offs between power and accuracy for traits controlled by different types of genetic architectures. FarmCPU provides the most favourable outcomes for moderately complex traits while a Bayesian approach adopted from genomic prediction provides the most favourable outcomes for extremely complex traits. We assert that by estimating the complexity of genetic architectures for target traits and selecting an appropriate statistical approach for the degree of complexity detected, researchers can substantially improve the ability to dissect the genetic factors controlling complex traits such as flowering time, plant height and yield component
BIOMECHANICAL ANALYSIS ON THE EFFECT OF WEIGHTLIFTING TRAINING ON WOMEN'S HEIGHT
SUMMARY - In order to promote the development of weightlifting exercises of woman, the receive-stresses condition of trial lift at each moment were analyzed by using high-speed photographic method, the stresses distributions and the relationship between stresses on bone and lifting weight were studied. In the meantime, we investigated 75 woman weightlifting players from the whole country, the growth capacities of height are compared with the same age section of female, more over the reality heights are contrasted with the high of attainable in the light of heredity genetic factor. The result shows: Although the stresses in depth of trial lift on bone is more than ordinary person, the stimulation of stresses may play an important part in the growth of bone, that is within regular sphere, the stresses can promote the growth of bone. Of 75 woman players through 4 years training, the average growth capacity of height every years is 0.78 cm, which belongs normal sphere and reaches the heights in the light of heredity gene calculating. So weightlifting training doesn't hamper the growth of height, and it may play a positive role in that. Main reference. 1. Chinese physical quality and healthy research - Chinese Education publishing House 2 . The biomechanical basis of bone sys- tem - Xue Lin publishing House
Three-dimensional structure of the milky way dust: modeling of LAMOST data
We present a three-dimensional modeling of the Milky Way dust distribution by
fitting the value-added star catalog of LAMOST spectral survey. The global dust
distribution can be described by an exponential disk with scale-length of 3,192
pc and scale height of 103 pc. In this modeling, the Sun is located above the
dust disk with a vertical distance of 23 pc. Besides the global smooth
structure, two substructures around the solar position are also identified. The
one located at and is
consistent with the Gould Belt model of \citet{Gontcharov2009}, and the other
one located at and is
associated with the Camelopardalis molecular clouds.Comment: 15 pages, 6 figure, accepted by Ap
SAW Delay Line based Smart Sensing in Water Distribution System
Wireless Passive Surface Acoustic Wave (SAW) sensors have attracted great attention in numerous applications. They are powered by interrogating Radio Frequency (RF) pulses rather than batteries. In this study, a wireless passive SAW temperature and pressure delay line sensor was adapted in a designed framework which can control the ambient liquid temperature and pressure and characterised. The experimental results meet the theoretical analysis that the related phase delay of the response signal depends linearly on the temperature (pressure) when the pressure (temperature) keeps constant
The Heterogeneity in the Landscape of Gene Dominance in Maize is Accompanied by Unique Chromatin Environments
Subgenome dominance after whole-genome duplication (WGD) has been observed in many plant species. However, the degree to which the chromatin environment affects this bias has not been explored. Here, we compared the dominant subgenome (maize1) and the recessive subgenome (maize2) with respect to patterns of sequence substitutions, genes expression, transposable element accumulation, small interfering RNAs, DNA methylation, histone modifications, and accessible chromatin regions (ACRs). Our data show that the degree of bias between subgenomes for all the measured variables does not vary significantly when both of the WGD genes are located in pericentromeric regions. Our data further indicate that the location of maize1 genes in chromosomal arms is pivotal for maize1 to maintain its dominance, but location has a less effect on maize2 homoeologs. In addition to homoeologous genes, we compared ACRs, which often harbor cis-regulatory elements, between the two subgenomes and demonstrate that maize1 ACRs have a higher level of chromatin accessibility, a lower level of sequence substitution, and are enriched in chromosomal arms. Furthermore, we find that a loss of maize1 ACRs near their nearby genes is associated with a reduction in purifying selection and expression of maize1 genes relative to their maize2 homoeologs. Taken together, our data suggest that chromatin environment and cis-regulatory elements are important determinants shaping the divergence and evolution of duplicated genes
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