1,212 research outputs found
Graphs of gonality three
In 2013, Chan classified all metric hyperelliptic graphs, proving that
divisorial gonality and geometric gonality are equivalent in the hyperelliptic
case. We show that such a classification extends to combinatorial graphs of
divisorial gonality three, under certain edge- and vertex-connectivity
assumptions. We also give a construction for graphs of divisorial gonality
three, and provide conditions for determining when a graph is not of divisorial
gonality three.Comment: 19 pages, 13 figures; corrected statements of Theorems 1.2 and 4.1,
as well as material in Section
PCR-based method for identifying a fusarium wilt-resistant genotype in plants
The present invention provides a sensitive assay for objectively determining the genotype of cucurbit plants, particularly species of melon, with respect to resistance or susceptibility to Fusarium wilt infection. The assay of the present invention uses a polymerase chain reaction to amplify sample DNA using either an AM or FM oligonucleotide primer pair. The PCR product which results from either primer pair differs in size, depending upon whether the template DNA was obtained from a plant susceptible or resistant to Fusarium wilt, permitting easy and rapid identification of plant genotype
A Model for the Internal Structure of Molecular Cloud Cores
We generalize the classic Bonnor-Ebert stability analysis of
pressure-truncated, self-gravitating gas spheres, to include clouds with
arbitrary equations of state. A virial-theorem analysis is also used to
incorporate mean magnetic fields into such structures. The results are applied
to giant molecular clouds (GMCs), and to individual dense cores, with an eye to
accounting for recent observations of the internal velocity-dispersion profiles
of the cores in particular. We argue that GMCs and massive cores are at or near
their critical mass, and that in such a case the size-linewidth and mass-radius
relations between them are only weakly dependent on their internal structures;
any gas equation of state leads to essentially the same relations. We briefly
consider the possibility that molecular clouds can be described by polytropic
pressure-density relations (of either positive or negative index), but show
that these are inconsistent with the apparent gravitational virial equilibrium,
2U + W = 0 of GMCs and of massive cores. This class of models would include
clouds whose nonthermal support comes entirely from Alfven wave pressure. The
simplest model consistent with all the salient features of GMCs and cores is a
``pure logotrope,'' in which P/P_c = 1 + A ln(rho/rho_c). Detailed comparisons
with data are made to estimate the value of A, and an excellent fit to the
observed dependence of velocity dispersion on radius in cores is obtained with
A = 0.2.Comment: 33 pages, LaTeX with 3 PS figures; ApJ in press (October 1 1996
The evolutionary history of Cytochrome P450 genes in four filamentous Ascomycetes
BACKGROUND: The Cytochrome P450 system is important in fungal evolution for adapting to novel ecological niches. To elucidate the evolutionary process of cytochrome P450 genes in fungi with different life styles, we studied the patterns of gene gains and losses in the genomes of four filamentous Ascomycetes, including two saprotrophs (Aspergillus nidulans (AN) and Neurospora crassa (NC)) and two plant pathogens (Fusarium graminearum (FG) and Magnaporthe grisea (MG)). RESULTS: A total of 376 P450 genes were assigned to 168 families according to standard nomenclature. On average, only 1 to 2 genes per family were in each genome. To resolve conflicting results between different clustering analyses and standard family designation, a higher order relationship was formulated. 376 genes were clustered into 115 clans. Subsequently a novel approach based on parsimony was developed to build the evolutionary models. Based on these analyses, a core of 30 distinct clans of P450s was defined. The core clans experienced contraction in all four fungal lineages while new clans expanded in all with exception of NC. MG experienced more genes and clans gains compared to the other fungi. Parsimonious analyses unanimously supported one species topology for the four fungi. CONCLUSION: The four studied fungi exhibit unprecedented diversity in their P450omes in terms of coding sequence, intron-exon structures and genome locations, suggesting a complicated evolutionary history of P450s in filamentous Ascomycetes. Clan classification and a novel strategy were developed to study evolutionary history. Contraction of core clans and expansion of novel clans were identified. The exception was the NC lineage, which exhibited pure P450 gene loss
Regionalism Panel Discussion
Regionalism Panel Discussion Featuring: Mr. Jon Cooper, Mr. Ralph Schulz, and Mr. Michael Skipper. Moderated by Mayor Karl Dean. October 7, 201
Method of diagnosing gummy stem blight in plants using a polymerase chain reaction assay
The present invention provides a sensitive test for objectively diagnosing the presence of Didymella bryoniae, the causative agent of gummy stem blight, and differentiating it from similar, nonpathogenic Phoma species. The assay is applicable to DNA isolated from extracts from plant leaves, stem or seed. The detection method employs a polymerase chain reaction technique, using specific oligonucleotide primers for amplification. PCR Products can be visualized using an ELISA-based calorimetric detection system
Method of diagnosing gummy stem blight in plants using a polymerase chain reaction assay
The present invention provides a sensitive test for objectively diagnosing the presence of Didymella bryoniae, the causative agent of gummy stem blight, and differentiating it from similar, nonpathogenic Phoma species. The assay is applicable to DNA isolated from extracts from plant leaves, stem or seed. The detection method employs a polymerase chain reaction technique, using specific oligonucleotide primers for amplification. PCR Products can be visualized using an ELISA-based colorimetric detection system
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