304 research outputs found
Description and molecular diagnosis of a new species of Brunfelsia (Solanaceae) from the Bolivian and Argentinean Andes
Brunfelsia plowmaniana N.Filipowicz & M.Nee sp. nov., a species from humid and cloud forests of the Bolivian and Argentinean Andes, is described and provided with a molecular diagnosis, using provisions available in the recently approved International Code of Nomenclature for algae, fungi and plants. Specimens belonging to the new species were previously placed in the polymorphic B. uniflora (Pohl) D.Don, which a molecular phylogeny revealed as polyphyletic. Revision of numerous collections revealed clear morphological differences between the new species and B. uniflora, the type locality of which is in the state of São Paulo, Brazil
The Boring Monopole
We study false vacuum decays catalysed by magnetic monopoles which act as
tunnelling sites with exponentially enhanced decay rates. The field profiles
describing the decay do not have the typically assumed symmetry,
thus requiring an extension of the usual decay rate calculation. To numerically
determine the saddle point solutions which describe the tunnelling process we
use a new algorithm based on the mountain pass theorem. This method can be
applied more widely to phase transitions with reduced symmetry, such as decays
away from the zero and infinite temperature limits. Our results show that
monopole-catalysed tunnelling can dominate over the homogeneous false vacuum
decay for a wide range of parameters, significantly modify the gravitational
wave signal or trigger phase transitions which would otherwise never complete.
A single boring monopole in our Hubble patch may determine the lifetime of the
Standard Model vacuum.Comment: 19 pages, 6 figures, Journal versio
15N NMR study of a mixture of uniformly labeled tRNAs
15N NMR spectra were taken of 15N-enriched tRNA extracted from bakers yeast; ammonium sulfate was used as a nitrogen source. The increase in the degree of denaturation of tRNA, which occurs with increase in temperature from 30 degrees C to 70 degrees C, resulted in no large changes in 15N chemical shifts at acidic and neutral pH but quite pronounced changes in proton-15N nuclear Overhauser effects
New species of Solanum and Capsicum (Solanaceae) from Bolivia, with clarification of nomenclature in some Bolivian Solanum
Journal ArticleBolivian floristic diversity is high, reflecting its great topographic and habitat diversity. Habitats in Bolivia range from seasonally flooded savannas to arid Chaco and high elevation deserts to hyper-humid montane and lowland rainforests
Methods of quantifying specialized knowledge and network rewiring
Technological innovations are a major driver of economic development that
depend on the exchange of knowledge and ideas among those with unique but
complementary specialized knowledge and knowhow. However, measurement of
specialized knowledge embedded in technologists, scientists and entrepreneurs
in the knowledge economy presents an empirical challenge as both the exchange
of knowledge and knowledge itself remain difficult to observe. We develop novel
measures of specialized knowledge using a unique dataset of longitudinal
records of participation at technology-focused meetup events in two regional
knowledge economics. Our measures of specialized knowledge can be further used
to quantify the extend of knowledge spillover and network rewiring and uncover
underlying social mechanisms that contribute to the development of increasingly
complex and differentiated networks in maturing knowledge economies. We apply
these methods in the context of the rapid morphogenesis of emerging regional
technology economies in New York City and Los Angeles.Comment: 21 pages, 6 figure
Solanaceae—A Model for Linking Genomics With Biodiversity
Recent progress in understanding the phylogeny of the economically important plant
family Solanaceae makes this an ideal time to develop models for linking the new
data on plant genomics with the huge diversity of naturally occurring species in the
family. Phylogenetics provides the framework with which to investigate these linkages
but, critically, good species-level descriptive resources for the Solanaceae community
are currently missing. Phylogeny in the family as a whole is briefly reviewed,
and the new NSF Planetary Biodiversity Inventories project ‘PBI: Solanum—a
worldwide treatment’ is described. The aims of this project are to provide species-level
information across the global scope of the genus Solanum and to make this available
over the Internet. The project is in its infancy, but will make available nomenclatural
information, descriptions, keys and illustrative material for all of the approximately
1500 species of Solanum. With this project, the opportunity of linking valid, up-to-date
taxonomic information about wild species of Solanum with the genomic information
being generated about the economically important species of the genus (potato, tomato
and eggplant) can be realized. The phylogenetic framework in which the PBI project is
set is also of enormous potential benefit to other workers on Solanum. The community
of biologists working with Solanaceae has a unique opportunity to effectively link
genomics and taxonomy for better understanding of this important family, taking
plant biology to a new level for the next century
I. Reactions of Bicyclo[3.3.0]octenyl Tosylates II. Nitrogen-15 Nuclear Magnetic Resonance Investigations of Organic Reactions
PART I
A. Elimination Reactions of 6-Bicyclo[3.2.0]-2-heptenyl Tosylates
The 6- and 7-bicyclo[3.3.0]-2-octenyl tosylates with 2,4,6-trimethylpyridine have been reported to yield mixtures of bicyclo[3.3.0]octa-2,6-diene and bicyclo[3.3.0]octa-2,7-diene. Under the same conditions, the stereoisomeric 6-bicyclo[3.2.0]-2-heptenyl tosylate gives ring-opened products, 1,3,5-cycloheptatriene and 5-ethylidene-1,3-cyclopentadiene.
B. Acetolysis of Some Bicyclo[3.3.0]-2-octenyl Tosylates
The products of the acetolysis of the stereoisomeric 6-,7-, and 8-bicyclo[3.3.0]-2-octenyl tosylates are reported. These tosylates were themselves stable to skeletal rearrangements, but were found to undergo 1,2-hydride shifts and elimination solvolysis.
PART II
Assignment of the Nitrogen-15 Nuclear Magnetic Resonances of Biotin and Unequivocal Synthesis of (+)-[1-15N]Biotin
The 15N NMR spectra of biotin, desthiobiotin, and 2-imidazolidinone were measured. Assignment of the resonances of biotin and desthiobiotin was achieved by off-resonance decoupling. The biotin assignment was confirmed by measurement of biotin specifically labeled with 15N at N1.
PART III
A 15N Nuclear Magnetic Resonance Study of the Base-Catalyzed -NH2 Exchange Reactions of Acetamide and Thioacetamide
The base-catalyzed -NH2 exchange reactions of acetamide and thioacetamide were studied by 15N nuclear magnetic resonance spectroscopy by use of line-shape analysis. The 15N NMR spectra of these primary amides at intermediate exchange rates were broad doublets, which indicated that the two amide protons were exchanging at different rates. The line-shape analysis indicated that the ratio of exchange rates was 6 ± 1 for acetamide and 3 ± 1 for thioacetamide.
PART IV
Determination of the Binding Interactions of cis-[Pt(NH3)2Cl2] with Nucleosides by 15N Nuclear Magnetic Resonance Spectroscopy
The 15N NMR chemical shifts and 15N-195Pt coupling constants of several platinum(II)-ammine complexes were measured. The magnitude of the coupling constants were dependent on the trans ligand. A similar dependence on the trans ligand was found for the 15N chemical shifts of the coordinated ammonia ligands. The magnitude of the 15N platinum coordination shift was proportional to the 15N protonation shift of the ligand. Cis-[Pt(NH3)2Cl2] was found to bind to guanosine through N7 and another nitrogen site. The drug also binds to N3 of cytidine and to all four of the nitrogen sites of adenosine. No evidence was found to support chelate binding of nucleosides by cis-[Pt(NH3)2Cl2].</p
Sinopsis de Acalypha L. (Euphorbiaceae) de Perú y Bolivia, con la descripción de una nueva especie
A critical review of the Peruvian and Bolivian species of Acalypha L. (Euphorbiaceae) is presented. As a result 41 species (42 taxa) are accepted, 31 from Peru and 28 from Bolivia, and 94 names are considered synonyms. A new species is described and illustrated, A. psamofila, based on Bolivian material. Comprehensive nomenclatural information is supplied and 36 lectotypes and one neotype are designated. An identification key is also provided, as well as original illustrations of six species and distribution maps of all the accepted species.Se presenta una revisión crítica de las especies de Acalypha L. (Euphorbiaceae) presentes en Bolivia y Perú. Como resultado se reconocen 41 especies (42 táxones), 31 para Perú y 28 para Bolivia, y 94 nombres son considerados sinónimos. Se describe e ilustra una nueva especie, A. psamofila, basada en material boliviano. Se aporta una exhaustiva información nomenclatural y se designan 36 lectótipos y un neótipo. Se incluye también una clave de identificación, así como ilustraciones originales de seis especies y mapas de distribución de todas las especies aceptadas
Synopsis of <em>Acalypha</em> L. (Euphorbiaceae) of Peru and Bolivia, with description of a new species
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