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A bacterial gene-drive system efficiently edits and inactivates a high copy number antibiotic resistance locus.
Gene-drive systems in diploid organisms bias the inheritance of one allele over another. CRISPR-based gene-drive expresses a guide RNA (gRNA) into the genome at the site where the gRNA directs Cas9-mediated cleavage. In the presence of Cas9, the gRNA cassette and any linked cargo sequences are copied via homology-directed repair (HDR) onto the homologous chromosome. Here, we develop an analogous CRISPR-based gene-drive system for the bacterium Escherichia coli that efficiently copies a gRNA cassette and adjacent cargo flanked with sequences homologous to the targeted gRNA/Cas9 cleavage site. This "pro-active" genetic system (Pro-AG) functionally inactivates an antibiotic resistance marker on a high copy number plasmid with ~ 100-fold greater efficiency than control CRISPR-based methods, suggesting an amplifying positive feedback loop due to increasing gRNA dosage. Pro-AG can likewise effectively edit large plasmids or single-copy genomic targets or introduce functional genes, foreshadowing potential applications to biotechnology or biomedicine
The nucleon-nucleon potential beyond the static approximation
We point out that, due to the use of static nucleon propagators in Heavy
Baryon Chiral Perturbation Theory, the current calculations of the
nucleon-nucleon potential miss certain contributions starting at two loops.
These contributions give rise to contact interactions, which are both
parametrically and numerically more important than the so called NNLO
potentials. They show a peculiar dependence on the light quark masses, which
should be taken into account when performing chiral extrapolations of lattice
data. However, they do not appear to have an impact on phenomenology since they
can be absorbed into redefinitions of unknown parameters which are usually
fitted to data.Comment: 20 pages. Misprints corrected, explanations and references added.
Journal version. Corrected misprints in formulas 30,31 and 32 in Journal
versio
Long-distance structure of the X(3872)
We investigate heavy quark symmetries for heavy meson hadronic molecules, and
explore the consequences of assuming the X(3872) and as an
isoscalar and an isovector hadronic molecules,
respectively. The symmetry allows to predict new hadronic molecules, in
particular we find an isoscalar bound state with a mass
about 10580 MeV and the isovector charmonium partners of the and
the states. Next, we study the
three body decay. This decay mode is more sensitive to the long-distance
structure of the X(3872) resonance than its and
decays, which are mainly controlled by the short distance part of the X(3872)
molecular wave function. We discuss the final state
interactions, which in some situations become quite important. Indeed in these
cases, a precise measurement of this partial decay width could provide precise
information on the interaction strength between the charm
mesons.Comment: Talk presented at the "XI International Conference on Hyperons, Charm
and Beauty Hadrons (BEACH 2014)", Birmingham (U.K.), July 201
The Heavy Quark Spin Symmetry Partners of the X(3872)
We explore the consequences of heavy quark spin symmetry for the charmed
meson-antimeson system in a contact-range (or pionless) effective field theory.
As a trivial consequence, we theorize the existence of a heavy quark spin
symmetry partner of the X(3872), with , which we call X(4012) in
reference to its predicted mass. If we additionally assume that the X(3915) is
a heavy spin symmetry partner of the X(3872), we end up predicting a
total of six molecular states. We also discuss the error
induced by higher order effects such as finite heavy quark mass corrections,
pion exchanges and coupled channels, allowing us to estimate the expected
theoretical uncertainties in the position of these new states.Comment: 18 pages; final version accepted for publicatio
Renormalization of the Deuteron with One Pion Exchange
We analyze the deuteron bound state through the One Pion Exchange Potential.
We pay attention to the short distance peculiar singularity structure of the
bound state wave functions in coordinate space and the elimination of short
distance ambiguities by selecting the regular solution at the origin. We
determine the so far elusive amplitude of the converging exponential solutions
at the origin. All bound state deuteron properties can then be uniquely deduced
from the deuteron binding energy, the pion-nucleon coupling constant and pion
mass. This generates correlations among deuteron properties. Scattering phase
shifts and low energy parameters in the 3S1-3D1 channel are constructed by
requiring orthogonality of the positive energy states to the deuteron bound
state, yielding an energy independent combination of boundary conditions. We
also analyze from the viewpoint of short distance boundary conditions the weak
binding regime on the light of long distance perturbation theory and discuss
the approach to the chiral limit.Comment: 22 pages, 11 figure
Kohn-Sham calculations combined with an average pair-density functional theory
A recently developed formalism in which Kohn-Sham calculations are combined
with an ``average pair density functional theory'' is reviewed, and some new
properties of the effective electron-electron interaction entering in this
formalism are derived. A preliminary construction of a fully self-consitent
scheme is also presented in this framework.Comment: submitted to Int. J. Mod. Phys. B (proceedings of the 30th
International Workshop on Condensed Matter Theories
Renormalization of chiral two pion exchange NN interactions with delta excitations: correlations in the partial wave expansion
In this work we consider the renormalization of the chiral two-pion exchange
potential with explicit delta-excitations for nucleon-nucleon scattering at
next-to-leading (NLO) and next-to-next-to-leading order (N2LO). Due to the
singular nature of the chiral potentials, correlations between different
partial waves are generated. In particular we show that two-body scattering by
a short distance power like singular attractive interaction can be renormalized
in all partial waves with a single counterterm, provided the singularities are
identical. A parallel statement holds in the presence of tensor interactions
when the eigenpotentials in the coupled channel problem also coincide. While
this construction reduces the total number of counterterms to eleven in the
case of nucleon-nucleon scattering with chiral two-pion exchange interactions
with delta degrees of freedom, the differences in the scattering phases as
compared to the case with the uncorrelated partial wave renormalization become
smaller as the angular momentum is increased in the elastic scattering region.Comment: 20 pages, 8 figures, a section has been added discussing cut-off
dependence. Accepted for publication in PR
Un procedimiento para obtener clusters utilizando la D.V.S. de una matriz. Comparaciones con el biplot y con el modelo Q-factorial
Durante las últimas décadas, el análisis de un conjunto de n individuos medidos en p variables, proporcionando una matriz de datos Xn,p, mediante técnicas de representación que utilizan la Descomposición en Valores Singulares de la matriz Xn,p (o alguna derivada), han permitido resumir la información que aportan los datos en alguna forma óptima, siendo muy útil para indicar la presencia de clusters entre los n individuos y/o para prevenir ante posibles clasificaciones erróneas producidas por técnicas de agrupamiento más complejas. En este artículo estudiaremos un procedimiento que puede utilizarse en ocasiones para obtener clasificaciones naturales de un conjunto de datos, basado en la representación biplot y en el modelo Q-factorial que puede obtenerse a partir de la DVS
Renormalization of NN Interaction with Relativistic Chiral Two Pion Exchange
The renormalization of the NN interaction with the Chiral Two Pion Exchange
Potential computed using relativistic baryon chiral perturbation theory is
considered. The short distance singularity reduces the number of counter-terms
to about a half as those in the heavy-baryon expansion. Phase shifts and
deuteron properties are evaluated and a general overall agreement is observed.Comment: 13 pages, 4 figures. Reference included. Typos corrected. Appendix
and discussion adde
Caracterizacion sintomatologica y molecular del virus de la mancha anillada del papayo (PRSV) que infecta Carica papaya L. en el norte del Peru
The objective of present study was symptomatic and molecular characterization of the virus that infects Carica papaya L. in areas of northern Peru. To do this, of different fields were collected leaves of C. papaya with mosaic symptoms, chlorosis and distortion the leaf. Sap of these leaves was inoculated mechanically onto virus-free plants of C. papaya, Chenopodium murale, Ch. amaranticolor, Ch. quinoa, Cucumis melo, C. sativus and Cucurbita pepo; which they were kept at room temperature for 45 days, after which young leaves in of C. papaya, mosaic, distortion and reduction of the leaf blade was observed; in the species C. melo, C. sativus and Cucurbita pepo systemic chlorosis. Ch. murale, Ch. amaranticolor and Ch. quinoa they no showed symptoms evident. The plants infected were analyzed by serological technique NCM-ELISA and RT-PCR proving that the virus that is infecting the plantations assessed in the north of Peru, it is the papaya ringspot virus (RSVP).El presente trabajo tuvo como objetivo la caracterización sintomatológica y molecular del virus que infecta Carica papaya L. en zonas del norte peruano. Para ello, de diferentes campos en producción se colectaron hojas tiernas de C. papaya con síntomas de mosaico, clorosis, aclareo de nervaduras y distorsión de la lámina foliar. Savia de estas hojas fue inoculada en forma mecánica sobre plantas libres de virus de C. papaya, Chenopodium murale, Ch. amaranticolor, Ch. quinoa, Cucumis melo, C. sativus y Cucurbita pepo; las que fueron mantenidas a temperatura ambiente durante 45 días al cabo de los cuales en las hojas jóvenes de C. papaya se observó aclareo de nervaduras, mosaico, distorsión y reducción de la lámina foliar; en las especies C. melo, C. sativus y Cucurbita pepo clorosis sistémica, en Ch. murale, Ch. amaranticolor y Ch. quinoa no se evidenciaron sintomas. Las plantas de C. papaya, C. melo, C. sativus y Cucurbita pepo infectadas, fueron analizadas por la técnica serológica de NCM-ELISA y RT-PCR comprobándose que el virus que se encuentra infectando las plantaciones de las zonas evaluadas en el norte del Perú, es el virus de la mancha anillada del papayo (PRSV)
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