126 research outputs found
New records of biting midges of the genus Culicoides Latreille from Mexico (Diptera: Ceratopogonidae)
We provide the first records of six species of biting midges (Diptera: Ceratopogonidae) in the genus
Culicoides Latreille from Mexico: C. baueri Hoffman, C. castillae Fox, C. debilipalpis Lutz, C. iriartei Fox, C. leoni
Barbosa and C. pusilloides Wirth and Blanton. In addition, C. leopoldoi Ortiz is confirmed from Mexico, and new
records are included for 25 other species previously recorded in Mexico: C. arubae Fox and Hoffman, C. blantoni Vargas
and Wirth, C. crepuscularis Malloch, C. daedalus Macfie, C. diabolicus Hoffman, C. foxi Ortiz, C. furens (Poey), C.
gabaldoni Ortiz, C. haematopotus Malloch, C. hylas Macfie, C. insignis Lutz, C. jamaicensis Edwards, C. luteovenus
Root and Hoffman, C. neopulicaris Wirth, C. nigrigenus Wirth and Blanton, C. pampoikilus Macfie, C. panamensis
Barbosa, C. paraensis (Goeldi), C. phlebotomus (Williston), C. poikilonotus Macfie, C. pusillus Lutz, C. stigmalis Wirth,
and all three species in the C. (Monoculicoides) variipennis complex, C. variipennis (Coquillett), C. occidentalis Wirth
and Jones, and C. sonorensis Wirth and Jones
Fishery management in the lower Mesopotamian regions: population structure of Hyporhamphus limbatus (Valenciennes, 1847)
Continuing isolation of populations and interbreeding can direct to morphometric dissimilarities among fish populations. The present study was performed with the aim to define the stock structure of Hyporhamphus limbatus on the basis of morphometric and meristic characters. In total, 300 H. limbatus specimens were collected from the three sampling locations of the lower reaches of Mesopotamia and its coastal area. In total, 9 morphometric and 4 meristic traits were examined. Canonical discriminant analysis showed significant differences in each of the morphometric measurements and meristic characters among the fish from different sampling locations. The results of this study can be employed in expressing stock-specific management policies for H. limbatus from areas studied in the south of Iraq
Eosinophilic esophagitis, celiac disease, and immunoglobulin E–mediated allergy in a 2-year-old child
This communication was presented at XXVI National
Congress of SEAIC, Spanish Society of Allergology and
Clinical Immunology, Bilbao, Spain, 2008Celiac disease, eosinophilic esophagitis, and urticaria are 3 manifestations of food allergy with different pathogenic mechanisms. We report
the case of a 2-year-old child with digestive symptoms, slow growth, and severe asthma. The results of skin prick tests were positive to
several foods. Endoscopy revealed eosinophilic esophagitis and celiac disease. Treatment consisted of a gluten-free diet and a 1-month
course of oral corticosteroids. Endoscopy and biopsy fi ndings were normal at 5 years of age.
A gluten-free diet is the basis of treatment of celiac disease, but the role of an elimination diet in eosinophilic esophagitis is not well
established. Our patient also developed urticaria when exposed to milk and egg. We present, to our knowledge, the fi rst report of a patient
with celiac disease, eosinophilic esophagitis, and immediate-type immunoglobulin E–mediated food allergyEnfermedad celíaca, esofagitis eosinofílica y urticaria son tres manifestaciones clínicas de alergia a alimentos con diferente etiopatogénesis.
Describimos el caso de una niña de 2 años de edad con síntomas digestivos, retraso del desarrollo póndero-estatural y asma persistente.
Las pruebas cutáneas fueron positivas a varios alimentos. La endoscopia digestiva y biopsias mostraron signos de esofagitis eosinofílica y
enfermedad celíaca. Realizó dieta exenta de gluten y de los alimentos a los que estaba sensibilizada y siguió tratamiento con corticoides
orales un mes. A los 5 años de edad, la endoscopia digestiva alta y biopsias esofágicas fueron normales.
Una dieta exenta de gluten es la base del tratamiento de la enfermedad celiaca. Sin embargo, el papel de las dietas de eliminación en
la esofagitis eosinofílica no ha sido totalmente establecido. La paciente desarrolló además urticaria tras contacto con leche y huevo.
Presentamos el primer caso de enfermedad celiaca, esofagitis eosinofi lica y alergia alimentaria mediada por IgE en el mismo pacient
FCNC Processes from D-brane Instantons
Low string scale models might be tested at the LHC directly by their Regge
resonances. For such models it is important to investigate the constraints of
Standard Model precision measurements on the string scale. It is shown that
highly suppressed FCNC processes like K0- bar K^0 oscillations or leptonic
decays of the D0-meson provide non-negligible lower bounds on both the
perturbatively and surprisingly also non-perturbatively induced string theory
couplings. We present both the D-brane instanton formalism to compute such
amplitudes and discuss various possible scenarios and their constraints on the
string scale for (softly broken) supersymmetric intersecting D-brane models.Comment: 28 pages, 13 figures, reference added, 1 typo corrected, style file
adde
TeV-Scale Z' Bosons from D-branes
Generic D-brane string models of particle physics predict the existence of
extra U(1) gauge symmetries beyond hypercharge. These symmetries are not of the
E_6 class but rather include the gauging of Baryon and Lepton numbers as well
as certain Peccei-Quinn-like symmetries. Some of the U(1)'s have triangle
anomalies, but they are cancelled by a Green-Schwarz mechanism. The
corresponding gauge bosons typically acquire a mass of order the string scale
M_S by combining with two-index antisymmetric fields coming from the closed
string sector of the theory. We argue that in string models with a low string
scale M_S proportional to 1-10 TeV, the presence of these generic U(1)'s may be
amenable to experimental test. Present constraints from electroweak precision
data already set important bounds on the mass of these extra gauge bosons. In
particular, for large classes of models, rho-parameter constraints imply M_S >=
1.5 TeV. In the present scheme some fraction of the experimentally measured Z^0
mass would be due not to the Higgs mechanism, but rather to the mixing with
these closed string fields. We give explicit formulae for recently constructed
classes of intersecting D6- and D5-brane models yielding the Standard Model
(SM) fermion spectrum.Comment: 46 pages, LaTeX, JHEP.cls, 21 Figures. minor correction
Characterization of Local Attitudes Toward Immigration Using Social Media
Migration is a worldwide phenomenon that may generate different reactions in
the population. Attitudes vary from those that support multiculturalism and
communion between locals and foreigners, to contempt and hatred toward
immigrants. Since anti-immigration attitudes are often materialized in acts of
violence and discrimination, it is important to identify factors that
characterize these attitudes. However, doing so is expensive and impractical,
as traditional methods require enormous efforts to collect data. In this paper,
we propose to leverage Twitter to characterize local attitudes toward
immigration, with a case study on Chile, where immigrant population has
drastically increased in recent years. Using semi-supervised topic modeling, we
situated 49K users into a spectrum ranging from in-favor to against
immigration. We characterized both sides of the spectrum in two aspects: the
emotions and lexical categories relevant for each attitude, and the discussion
network structure. We found that the discussion is mostly driven by Haitian
immigration; that there are temporal trends in tendency and polarity of
discussion; and that assortative behavior on the network differs with respect
to attitude. These insights may inform policy makers on how people feel with
respect to migration, with potential implications on communication of policy
and the design of interventions to improve inter-group relations.Comment: 8 pages, accepted at Latin American Web Congress 2019 (co-located
with The Web Conference
SUSY Quivers, Intersecting Branes and the Modest Hierarchy Problem
We present a class of chiral non-supersymmetric D=4 field theories in which
quadratic divergences appear only at two loops. They may be depicted as ``SUSY
quivers'' in which the nodes represent a gauge group with extended e.g., N=4
SUSY whereas links represent bifundamental matter fields which transform as
chiral multiplets with respect to different N=1 subgroups. One can obtain this
type of field theories from simple D6-brane configurations on Type IIA string
theory compactified on a six-torus. We discuss the conditions under which this
kind of structure is obtained from D6-brane intersections. We also discuss some
aspects of the effective low-energy field theory. In particular we compute
gauge couplings and Fayet-Iliopoulos terms from the Born-Infeld action and show
how they match the field theory results. This class of theories may be of
phenomenological interest in order to understand the modest hierarchy problem
i.e., the stability of the hierarchy between the weak scale and a fundamental
scale of order 10-100 TeV which appears e.g. in low string scale models.
Specific D-brane models with the spectrum of the SUSY Standard Model and three
generations are presented.Comment: 36 pages, using JHEP3.cls, 8 figures. References update
Three-dimensional general relativistic hydrodynamics II: long-term dynamics of single relativistic stars
This is the second in a series of papers on the construction and validation
of a three-dimensional code for the solution of the coupled system of the
Einstein equations and of the general relativistic hydrodynamic equations, and
on the application of this code to problems in general relativistic
astrophysics. In particular, we report on the accuracy of our code in the
long-term dynamical evolution of relativistic stars and on some new physics
results obtained in the process of code testing. The tests involve single
non-rotating stars in stable equilibrium, non-rotating stars undergoing radial
and quadrupolar oscillations, non-rotating stars on the unstable branch of the
equilibrium configurations migrating to the stable branch, non-rotating stars
undergoing gravitational collapse to a black hole, and rapidly rotating stars
in stable equilibrium and undergoing quasi-radial oscillations. The numerical
evolutions have been carried out in full general relativity using different
types of polytropic equations of state using either the rest-mass density only,
or the rest-mass density and the internal energy as independent variables. New
variants of the spacetime evolution and new high resolution shock capturing
(HRSC) treatments based on Riemann solvers and slope limiters have been
implemented and the results compared with those obtained from previous methods.
Finally, we have obtained the first eigenfrequencies of rotating stars in full
general relativity and rapid rotation. A long standing problem, such
frequencies have not been obtained by other methods. Overall, and to the best
of our knowledge, the results presented in this paper represent the most
accurate long-term three-dimensional evolutions of relativistic stars available
to date.Comment: 19 pages, 17 figure
Yukawa couplings in intersecting D-brane models
We compute the Yukawa couplings among chiral fields in toroidal Type II
compactifications with wrapping D6-branes intersecting at angles. Those models
can yield realistic standard model spectrum living at the intersections. The
Yukawa couplings depend both on the Kahler and open string moduli but not on
the complex structure. They arise from worldsheet instanton corrections and are
found to be given by products of complex Jacobi theta functions with
characteristics. The Yukawa couplings for a particular intersecting brane
configuration yielding the chiral spectrum of the MSSM are computed as an
example. We also show how our methods can be extended to compute Yukawa
couplings on certain classes of elliptically fibered CY manifolds which are
mirror to complex cones over del Pezzo surfaces. We find that the Yukawa
couplings in intersecting D6-brane models have a mathematical interpretation in
the context of homological mirror symmetry. In particular, the computation of
such Yukawa couplings is related to the construction of Fukaya's category in a
generic symplectic manifold.Comment: 47 pages, using JHEP3.cls, 11 figures. Typos and other minor
corrections. References adde
Three Dimensional Numerical General Relativistic Hydrodynamics I: Formulations, Methods, and Code Tests
This is the first in a series of papers on the construction and validation of
a three-dimensional code for general relativistic hydrodynamics, and its
application to general relativistic astrophysics. This paper studies the
consistency and convergence of our general relativistic hydrodynamic treatment
and its coupling to the spacetime evolutions described by the full set of
Einstein equations with a perfect fluid source. The numerical treatment of the
general relativistic hydrodynamic equations is based on high resolution shock
capturing schemes. These schemes rely on the characteristic information of the
system. A spectral decomposition for general relativistic hydrodynamics
suitable for a general spacetime metric is presented. Evolutions based on three
different approximate Riemann solvers coupled to four different discretizations
of the Einstein equations are studied and compared. The coupling between the
hydrodynamics and the spacetime (the right and left hand side of the Einstein
equations) is carried out in a treatment which is second order accurate in {\it
both} space and time. Convergence tests for all twelve combinations with a
variety of test beds are studied, showing consistency with the differential
equations and correct convergence properties. The test-beds examined include
shocktubes, Friedmann-Robertson-Walker cosmology tests, evolutions of
self-gravitating compact (TOV) stars, and evolutions of relativistically
boosted TOV stars. Special attention is paid to the numerical evolution of
strongly gravitating objects, e.g., neutron stars, in the full theory of
general relativity, including a simple, yet effective treatment for the surface
region of the star (where the rest mass density is abruptly dropping to zero).Comment: 45 pages RevTeX, 34 figure
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