oalib

OALib Journal期刊

ISSN: 2333-9721

费用：99美元

投稿

时间不限

( 2673 )

( 2672 )

( 2454 )

( 2208 )

自定义范围…

匹配条件： “ John S. Gardner and Mason G. Neipp” ，找到相关结果约590513条。
列表显示的所有文章，均可免费获取
第1页/共590513条
每页显示 条
Nectar for Plant Defense: the Feeding of the Non-Native Coccinellid Beetle, Curinus coeruleus, on Extra-Floral Nectaries of Hawaiian Native Hibiscus Brackenridgei
Kyra N. Krakos, Gary M. Booth, John S. Gardner and Mason G. Neipp
International Journal of Insect Science , 2012, DOI: 10.4137/IJIS.S7162
Abstract: The interaction between the non-native coccinellid beetle, Curinus coeruleus Mulsant, and the Hawaiian native plant Hibiscus brackenridgei A. Gray, was investigated on Kauai, HI. The presence of extra floral nectar appears to maintain the beetle presence on the plant. Because coccinellid beetles are predators on insects that are damaging to plants, beetle presence may increase plant fitness. Beetles were found feeding heavily on the extra floral nectaries of the Hibiscus. An examination of the beetle mouth parts with scanning electron microscopy revealed no structures specifically adapted for the consumption of nectar. The sensory ability of the coccinellids was tested to determine if they respond to visual or olfactory cues to detect the nectar. Studies with an eight-armed air-flow olfactometer concluded there was no olfactory cue. Tracing the pathways of beetles in laboratory experiments yielded results that suggest a visual cue. The extra floral nectaries are concluded to be a potential mechanism to maintain beetle presence on a plant to provide defense against herbivores.
Nectar for Plant Defense: the Feeding of the Non-Native Coccinellid Beetle, Curinus coeruleus, on Extra-Floral Nectaries of Hawaiian Native Hibiscus Brackenridgei
Kyra N. Krakos,Gary M. Booth,John S. Gardner,Mason G. Neipp
International Journal of Insect Science , 2011,
Abstract:
Characterizing Floral Symmetry in the Core Goodeniaceae with Geometric Morphometrics
Andrew G. Gardner,Dianella G. Howarth,John Menz,Jonathan N. Fitz Gerald,Kelly A. Shepherd,Rachel S. Jabaily
- , 2016, DOI: 10.1371/journal.pone.0154736
Abstract:
The Impact of |Delta I|=5/2 Transitions in K-> pi pi Decays
S. Gardner,G. Valencia
Physics , 2000, DOI: 10.1103/PhysRevD.62.094024
Abstract: We consider the impact of isospin violation on the analysis of K-> pi pi decays. We scrutinize, in particular, the phenomenological role played by the additional weak amplitude, of |Delta I|=5/2 in character, incurred by the presence of isospin violation. We show that Watson's theorem is appropriate in O(m_d-m_u), so that the inferred pi-pi phase shift at sqrt{s}=m_K determines the strong phase difference between the I=0 and I=2 amplitudes in K-> pi pi decay. We find the magnitude of the |Delta I|=5/2 amplitude thus implied by the empirical branching ratios to be larger than expected from estimates of isospin-violating strong and electromagnetic effects. We effect a new determination of the octet and 27-plet coupling constants with strong-interaction isospin violation and with electromagnetic effects, as computed by Cirigliano, Donoghue, and Golowich, and find that we are unable to resolve the difficulty. Exploring the role of |Delta I|=5/2 transitions in the CP-violating observable epsilon'/epsilon, we determine that the presence of a |Delta I|=5/2 amplitude impacts the empirical determination of omega, the ratio of the real parts of the |Delta I|=3/2 to |Delta I|=1/2 amplitudes, and that it generates a decrease in the estimation of epsilon'/epsilon.
Additional Isospin-Breaking Effects in ε^\prime/ε
S. Gardner,G. Valencia
Physics , 1999, DOI: 10.1016/S0370-2693(99)01164-8
Abstract: In the analysis of \epsilon^\prime/\epsilon it has been traditional to consider the isospin-breaking effects arising from electroweak-penguin contributions and from \pi^0-\eta and \pi^0-\eta^\prime mixing, yet additional isospin-violating effects exist. In particular, we study the isospin violation which arises from the u-d quark mass difference in the hadronization of the gluonic penguin operator, engendering contributions of an effective \Delta I=3/2 character. Using chiral perturbation theory and the factorization approximation for the hadronic matrix elements, we find within a specific model for the low-energy constants that we can readily accommodate an increase in \epsilon^\prime/\epsilon by a factor of two.
Determinants of Catch-Up Growth in International Adoptees from Eastern Europe
Bradley S Miller, Maria G Kroupina, Patrick Mason, Sandra L Iverson, Christine Narad, John H Himes, Dana E Johnson, Anna Petryk
International Journal of Pediatric Endocrinology , 2010, DOI: 10.1155/2010/107252
Abstract: Since 2000, over 160,000 children have come to the United States as international adoptees [1]. More than 25% of these children have come from Eastern European countries having received primarily institutional care. Children in these orphanages frequently endure significant social deprivation that may impact their physical growth due to suppression of hypothalamic function with consequent low levels of growth factors [2]. We and others have previously documented significant physical growth delays in up to 34% of international adoptees from Eastern Europe, South America, and Asia [3–5]. Of the many hereditary, environmental, and hormonal factors that may contribute, we have previously shown that age, prenatal factors (birth weight and risk of fetal alcohol syndrome), and growth factors (Insulin-like Growth Factor Binding Protein-3, IGFBP-3) are independently associated with the degree of growth delay in adoptees upon arrival into the US [4].A rapid period of catch-up growth (CUG) is seen following a variety of growth delays when the causative conditions improve. The Growth Hormone-(GH-)Insulin-like Growth Factor (IGF) system is known to be involved in CUG following many causes of growth delay, but limited data are available on the role of GH-IGF system in CUG following adoption [6]. The goal of this prospective longitudinal study was to examine the determinants of CUG in 148 postinstitutionalized international adoptees during the first 6 months after arrival into their adoptive families. We aimed to identify baseline factors that would help predict subsequent CUG and therefore help counsel the families, the degree of CUG, the usefulness of obtaining IGF-I and IGFBP-3 levels, and the impact of nutrition on CUG and the physiologic roles of nutrition and the growth hormone system on CUG.Participants were part of a longitudinal study of growth of institutionalized children adopted into the USA from Eastern Europe (Russia, Kazakhstan, and Ukraine). The study was approved
Widespread Triploidy in Western North American Aspen (Populus tremuloides)
Karen E. Mock, Colin M. Callahan, M. Nurul Islam-Faridi, John D. Shaw, Hardeep S. Rai, Stewart C. Sanderson, Carol A. Rowe, Ronald J. Ryel, Michael D. Madritch, Richard S. Gardner, Paul G. Wolf
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0048406
Abstract: We document high rates of triploidy in aspen (Populus tremuloides) across the western USA (up to 69% of genets), and ask whether the incidence of triploidy across the species range corresponds with latitude, glacial history (as has been documented in other species), climate, or regional variance in clone size. Using a combination of microsatellite genotyping, flow cytometry, and cytology, we demonstrate that triploidy is highest in unglaciated, drought-prone regions of North America, where the largest clone sizes have been reported for this species. While we cannot completely rule out a low incidence of undetected aneuploidy, tetraploidy or duplicated loci, our evidence suggests that these phenomena are unlikely to be significant contributors to our observed patterns. We suggest that the distribution of triploid aspen is due to a positive synergy between triploidy and ecological factors driving clonality. Although triploids are expected to have low fertility, they are hypothesized to be an evolutionary link to sexual tetraploidy. Thus, interactions between clonality and polyploidy may be a broadly important component of geographic speciation patterns in perennial plants. Further, cytotypes are expected to show physiological and structural differences which may influence susceptibility to ecological factors such as drought, and we suggest that cytotype may be a significant and previously overlooked factor in recent patterns of high aspen mortality in the southwestern portion of the species range. Finally, triploidy should be carefully considered as a source of variance in genomic and ecological studies of aspen, particularly in western U.S. landscapes.
High-Density SNP Genotyping of Tomato (Solanum lycopersicum L.) Reveals Patterns of Genetic Variation Due to Breeding
Sung-Chur Sim, Allen Van Deynze, Kevin Stoffel, David S. Douches, Daniel Zarka, Martin W. Ganal, Roger T. Chetelat, Samuel F. Hutton, John W. Scott, Randolph G. Gardner, Dilip R. Panthee, Martha Mutschler, James R. Myers, David M. Francis
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0045520
Abstract: The effects of selection on genome variation were investigated and visualized in tomato using a high-density single nucleotide polymorphism (SNP) array. 7,720 SNPs were genotyped on a collection of 426 tomato accessions (410 inbreds and 16 hybrids) and over 97% of the markers were polymorphic in the entire collection. Principal component analysis (PCA) and pairwise estimates of Fst supported that the inbred accessions represented seven sub-populations including processing, large-fruited fresh market, large-fruited vintage, cultivated cherry, landrace, wild cherry, and S. pimpinellifolium. Further divisions were found within both the contemporary processing and fresh market sub-populations. These sub-populations showed higher levels of genetic diversity relative to the vintage sub-population. The array provided a large number of polymorphic SNP markers across each sub-population, ranging from 3,159 in the vintage accessions to 6,234 in the cultivated cherry accessions. Visualization of minor allele frequency revealed regions of the genome that distinguished three representative sub-populations of cultivated tomato (processing, fresh market, and vintage), particularly on chromosomes 2, 4, 5, 6, and 11. The PCA loadings and Fst outlier analysis between these three sub-populations identified a large number of candidate loci under positive selection on chromosomes 4, 5, and 11. The extent of linkage disequilibrium (LD) was examined within each chromosome for these sub-populations. LD decay varied between chromosomes and sub-populations, with large differences reflective of breeding history. For example, on chromosome 11, decay occurred over 0.8 cM for processing accessions and over 19.7 cM for fresh market accessions. The observed SNP variation and LD decay suggest that different patterns of genetic variation in cultivated tomato are due to introgression from wild species and selection for market specialization.
Rescattering and chiral dynamics in B\to ρπdecay
S. Gardner,Ulf-G. Mei？ner
Physics , 2001, DOI: 10.1103/PhysRevD.65.094004
Abstract: We examine the role of B^0(\bar B^0) \to \sigma \pi^0 \to \pi^+\pi^- \pi^0 decay in the Dalitz plot analysis of B^0 (\bar B^0) \to \rho\pi \to \pi^+\pi^-\pi^0 decays, employed to extract the CKM parameter \alpha. The \sigma \pi channel is significant because it can break the relationship between the penguin contributions in B\to\rho^0\pi^0, B\to\rho^+\pi^-, and B\to\rho^-\pi^+ decays consequent to an assumption of isospin symmetry. Its presence thus mimics the effect of isospin violation. The \sigma\pi^0 state is of definite CP, however; we demonstrate that the B\to\rho\pi analysis can be generalized to include this channel without difficulty. The \sigma or f_0(400-1200) ``meson'' is a broad I=J=0 enhancement driven by strong \pi\pi rescattering; a suitable scalar form factor is constrained by the chiral dynamics of low-energy hadron-hadron interactions - it is rather different from the relativistic Breit-Wigner form adopted in earlier B\to\sigma\pi and D\to\sigma\pi analyses. We show that the use of this scalar form factor leads to an improved theoretical understanding of the measured ratio Br(\bar B^0 \to \rho^\mp \pi^\pm) / Br(B^-\to \rho^0 \pi^-).
Magnetic Pyrochlore Oxides
Jason S. Gardner,Michel J. P. Gingras,John E. Greedan
Physics , 2009, DOI: 10.1103/RevModPhys.82.53
Abstract: Within the past 20 years or so, there has occurred an explosion of interest in the magnetic behavior of pyrochlore oxides of the type $A_{2}^{3+}$$B_{2}^{4+}$O$_{7}$ where $A$ is a rare-earth ion and $B$ is usually a transition metal. Both the $A$ and $B$ sites form a network of corner-sharing tetrahedra which is the quintessential framework for a geometrically frustrated magnet. In these systems the natural tendency to form long range ordered ground states in accord with the Third Law is frustrated, resulting in some novel short range ordered alternatives such as spin glasses, spin ices and spin liquids and much new physics. This article attempts to review the myriad of properties found in pyrochlore oxides, mainly from a materials perspective, but with an appropriate theoretical context.
第1页/共590513条
每页显示 条


Home
Copyright © 2008-2020 Open Access Library. All rights reserved.