372 research outputs found
Adaptability of Scanning Electron Microscopy to Studies of Pollen Morphology
We have explored methods to achieve excellent results in study of the pollen grain wall by using only one electron microscope, the scanning electron microscope (SEM). While the secondary electron imaging mode, the most common in use, has great value in characterizing the exine surface it is possible to obtain a more comprehensive representation of pollen grain walls by expanding the capability of the secondary mode and making use of backscatter and transmission imaging detectors. In this way information is obtained about internal exine features that are likely to be more stable phylogenetically than the generally late-to-form surface structure. We illustrate the usefulness of natural and induced fractures, cryornicrotomy, thin-section examination, section deplasticization, localized acetolysis and pollen erosion by ionic bombardment in imaging exine structure. Techniques for expanding the use of SEM in taxonomic studies of mature pollen grain walls are outlined in flow chart sketches and illustrated with numerous examples from angiosperm pollen
Comparison of David V valve-sparing root replacement and bioprosthetic valve conduit for aortic root aneurysm
ObjectiveValve sparing root replacement (VSRR) is an attractive option for the management of aortic root aneurysms with a normal native aortic valve. Therefore, we reviewed our experience with a modification of the David V VSRR and compared it with stented pericardial bioprosthetic valve conduit (BVC) root replacement in an age-matched cohort of older patients.MethodsA total of 48 VSRRs were performed at our institution, excluding those on bicuspid aortic valves. We compared these cases with 15 aortic root replacements performed using a BVC during the same period. Subgroup analysis was performed comparing 16 VSRR cases and 15 age-matched BVC cases.ResultsThe greatest disparity between the VSRR and BVC groups was age (53 vs 69 years, respectively; P < .0005). The matched patients were similar in terms of baseline demographics and differed only in concomitant coronary artery bypass grafting (2 VSRR vs 7 BVC patients; P = .036). None of the VSRR and 3 of the BVC procedures were performed for associated dissection (P = .101). Postoperative aortic insufficiency grade was significantly different between the 2 groups (P = .004). The cardiopulmonary bypass, crossclamp, and circulatory arrest times were not different between the VSRR and BVC groups (174 vs 187 minutes, P = .205; 128 vs 133 minutes, P = .376; and 10 vs 13 minutes, respectively; P = .175). No differences were found between the 2 groups with respect to postoperative complications. One postoperative death occurred in the BVC group and none in the VSRR group. The postoperative length of stay and aortic valve gradients were less in the VSRR group (6 vs 8 days, P = .038; 6 vs 11.4 mm Hg, P = .001). The intensive care unit length of stay was significantly less in the VSRR group (54 vs 110 hours, P = .001).ConclusionsVSRR is an effective alternative to the BVC for aortic root aneurysm
The Operophtera brumata Nucleopolyhedrovirus (OpbuNPV) Represents an Early, Divergent Lineage within Genus Alphabaculovirus
Operophtera brumata nucleopolyhedrovirus (OpbuNPV) infects the larvae of the winter moth, Operophtera brumata. As part of an effort to explore the pesticidal potential of OpbuNPV, an isolate of this virus from Massachusetts (USA)âOpbuNPV-MAâwas characterized by electron microscopy of OpbuNPV occlusion bodies (OBs) and by sequencing of the viral genome. The OBs of OpbuNPV-MA consisted of irregular polyhedra and contained virions consisting of a single rod-shaped nucleocapsid within each envelope. Presumptive cypovirus OBs were also detected in sections of the OB preparation. The OpbuNPV-MA genome assembly yielded a circular contig of 119,054 bp and was found to contain little genetic variation, with most polymorphisms occurring at a frequency of \u3c 6%. A total of 130 open reading frames (ORFs) were annotated, including the 38 core genes of Baculoviridae, along with five homologous repeat (hr) regions. The results of BLASTp and phylogenetic analysis with selected ORFs indicated that OpbuNPV-MA is not closely related to other alphabaculoviruses. Phylogenies based on concatenated core gene amino acid sequence alignments placed OpbuNPV-MA on a basal branch lying outside other alphabaculovirus clades. These results indicate that OpbuNPV-MA represents a divergent baculovirus lineage that appeared early during the diversification of genus Alphabaculovirus
Draft Genome Sequence of Bowmanella denitrificans JL63, a Bacterium Isolated from Whiteleg Shrimp (\u3cem\u3eLitopenaeus vannamei\u3c/em\u3e) That Can Inhibit the Growth of Vibrio Parahaemolyticus
Bowmanella denitrificans strain JL63 was isolated from a whiteleg shrimp (Litopenaeus vannamei) and was determined to have antibacterial activity against an acute hepatopancreatic necrosis disease (AHPND) strain of Vibrio parahaemolyticus. Here, we report the draft genome sequence of this strain and identify genes that are potentially involved in its antibacterial activity
Stakeholder Theory and Marketing: Moving from a Firm-Centric to a Societal Perspective
This essay is inspired by the ideas and research examined in the special section on âStakeholder Marketingâ of the Journal of Public Policy & Marketing in 2010. The authors argue that stakeholder marketing is slowly coalescing with the broader thinking that has occurred in the stakeholder management and ethics literature streams during the past quarter century. However, the predominant view of stakeholders that many marketers advocate is still primarily pragmatic and company centric. The position advanced herein is that stronger forms of stakeholder marketing that reflect more normative, macro/societal, and network-focused orientations are necessary. The authors briefly explain and justify these characteristics in the context of the growing âprosocietyâ and âproenvironmentâ perspectivesâorientations that are also in keeping with the public policy focus of this journal. Under the âhard formâ of stakeholder theory, which the authors endorse, marketing managers must realize that serving stakeholders sometimes requires sacrificing maximum profits to mitigate outcomes that would inflict major damage on other stakeholders, especially society
Do Solar Neutrino Experiments Imply New Physics?
None of the 1000 solar models in a full Monte Carlo simulation is consistent
with the results of the chlorine or the Kamiokande experiments. Even if the
solar models are forced artifically to have a \b8 neutrino flux in agreeement
with the Kamiokande experiment, none of the fudged models agrees with the
chlorine observations. The GALLEX and SAGE experiments, which currently have
large statistical uncertainties, differ from the predictions of the standard
solar model by and , respectively.Comment: 7 pages (figures not included), Institute for Advanced Study number
AST 92/51. For a hard copy with the figures, write: [email protected]
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