111 research outputs found
Single top-quark production by strong and electroweak supersymmetric flavor-changing interactions at the LHC
(Abridged) We report on a complete study of the single top-quark production
by direct supersymmetric flavor-changing neutral-current (FCNC) processes at
the LHC. The total cross section for pp(gg)->t\bar{c}+\bar{t}c is computed at
the 1-loop order within the unconstrained Minimal Supersymmetric Standard Model
(MSSM). The present study extends the results of the supersymmetric strong
effects (SUSY-QCD), which were advanced by some of us in a previous work, and
includes the computation of the full supersymmetric electroweak corrections
(SUSY-EW). Our analysis of pp(gg)->t\bar{c}+\bar{t}c in the MSSM has been
performed in correspondence with the stringent low-energy constraints from b->s
gamma. In the most favorable scenarios, the SUSY-QCD contribution can give rise
to production rates of around 10^5 events per 100 fb^{-1} of integrated
luminosity. Furthermore, we show that there exist regions of the MSSM parameter
space where the SUSY-EW correction becomes sizeable. In the SUSY-EW favored
regions, one obtains lower, but still appreciable, event production rates that
can reach the 10^3 level for the same range of integrated luminosity. We study
also the possible reduction in the maximum event rate obtained from the full
MSSM contribution if we additionally include the constraints from
B^0_s-\bar{B}^0_s. In view of the fact that the FCNC production of heavy quark
pairs of different flavors is extremely suppressed in the SM, the detection of
a significant number of these events could lead to evidence of new physics --
of likely supersymmetric origin.Comment: LaTex, 35 pages, typos corrected. Version accepted in JHE
Magnetism of small V clusters embedded in a Cu fcc matrix: an ab initio study
We present extensive first principles density functional theory (DFT)
calculations dedicated to analyze the magnetic and electronic properties of
small V clusters (n=1,2,3,4,5,6) embedded in a Cu fcc matrix. We consider
different cluster structures such as: i) a single V impurity, ii) several
V dimers having different interatomic distance and varying local atomic
environment, iii) V and iv) V clusters for which we assume compact
as well as 2- and 1-dimensional atomic configurations and finally, in the case
of the v) V and vi) V structures we consider a square pyramid and a
square bipyramid together with linear arrays, respectively. In all cases, the V
atoms are embedded as substitutional impurities in the Cu network. In general,
and as in the free standing case, we have found that the V clusters tend to
form compact atomic arrays within the cooper matrix. Our calculated non
spin-polarized density of states at the V sites shows a complex peaked
structure around the Fermi level that strongly changes as a function of both
the interatomic distance and local atomic environment, a result that
anticipates a non trivial magnetic behavior. In fact, our DFT calculations
reveal, in each one of our clusters systems, the existence of different
magnetic solutions (ferromagnetic, ferrimagnetic, and antiferromagnetic) with
very small energy differences among them, a result that could lead to the
existence of complex finite-temperature magnetic properties. Finally, we
compare our results with recent experimental measurements.Comment: 7 pages and 4 figure
La capacidad del barorreflejo como índice de identificación de los pacientes de UCI preparados para el destete
Actualmente, la Prueba de Respiración Espontánea (SBT), indica si un paciente está listo para el destete de la ventilación mecánica. Sin embargo, en torno al 20% de los pacientes “preparados” para ser desintubados, realmente no lo estaban. En este trabajo, se ha estudiado la Capacidad del Barorreflejo durante la hora anterior a la SBT, y se ha visto que existen diferencias significativas entre los pacientes listos para el destete y los que realmente no lo estaban, sugiriendo que la predicción del éxito del destete puede ser mejorada con este nuevo índice
RBX: The new X-band SAR system from INTA
Revista oficial de la Asociación Española de Teledetección[EN] This paper describes the characteristics and the first results of the RBX system, the new airborne Synthetic Aperture Radar developed at Spanish National Institute of Aerospace Technology. The new system supports submetric resolution with interferometric and polarimetric capabilities. The system architecture has been designed taking into account an easy upgrade ability and the quality of the acquired data, including multiple internal calibration loops.[ES] Este artículo describe las características y los primeros resultados del sistema RBX, nuevo radar de apertura sintética aerotransportado que ha sido desarrollado en el Instituto Nacional de Técnica Aeroespacial. El nuevo sistema soporta resoluciones submétricas con capacidades interferométricas y polarimétricas. La arquitectura del sistema se ha diseñado teniendo en cuenta la facilidad de incorporar mejoras y la calidad de los datos adquiridos, incluyendo múltiples lazos de calibración interna.Larrañaga, J. R., De Porras Bernácer, R., Del Castillo, J., Gimeno, N., Aguilar, P., Baquero, A. M., . . . Sánchez, S. (2014). RBX: The new X-band SAR system from INTA. [RBX: El nuevo radar SAR en banda X del INTA] Revista De Teledeteccion, (41), 89-96. doi:10.4995/raet.2014.2285SWORD899641G. Bonin, P. Dreuillet. 2008. The new ONERA airborne SAR system SETHI. EUSAR, Dresden, Germany.Rodriguez, M. G. (2008). Design of a Coherent Generation and Acquisition System at 1,2GHz. 2008 4th Southern Conference on Programmable Logic. doi:10.1109/spl.2008.4547745Gonzalez Bonilla, M. J., Gomez Miguel, B., Cuerda Muñoz, J. M., Larrañaga Sudupe, J. R., Garcia Rodriguez, M., 2009. INTASAR program. Proceedings IGARSSHORN, RALF; NOTTENSTEINER, ANTON; SCHEIBER, ROLF. 2008. F-SAR – DLR's advanced airborne SAR system onboard DO228. Proceedings EUSARMoreira, A., & Yonghong Huang. (1994). Airborne SAR processing of highly squinted data using a chirp scaling approach with integrated motion compensation. IEEE Transactions on Geoscience and Remote Sensing, 32(5), 1029-1040. doi:10.1109/36.31289
A Model for the Development of the Rhizobial and Arbuscular Mycorrhizal Symbioses in Legumes and Its Use to Understand the Roles of Ethylene in the Establishment of these two Symbioses
We propose a model depicting the development of nodulation and arbuscular mycorrhizae. Both processes are dissected into many steps, using Pisum sativum L. nodulation mutants as a guideline. For nodulation, we distinguish two main developmental programs, one epidermal and one cortical. Whereas Nod factors alone affect the cortical program, bacteria are required to trigger the epidermal events. We propose that the two programs of the rhizobial symbiosis evolved separately and that, over time, they came to function together. The distinction between these two programs does not exist for arbuscular mycorrhizae development despite events occurring in both root tissues. Mutations that affect both symbioses are restricted to the epidermal program. We propose here sites of action and potential roles for ethylene during the formation of the two symbioses with a specific hypothesis for nodule organogenesis. Assuming the epidermis does not make ethylene, the microsymbionts probably first encounter a regulatory level of ethylene at the epidermis–outermost cortical cell layer interface. Depending on the hormone concentrations there, infection will either progress or be blocked. In the former case, ethylene affects the cortex cytoskeleton, allowing reorganization that facilitates infection; in the latter case, ethylene acts on several enzymes that interfere with infection thread growth, causing it to abort. Throughout this review, the difficulty of generalizing the roles of ethylene is emphasized and numerous examples are given to demonstrate the diversity that exists in plants
Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at TeV
The inclusive transverse momentum () distributions of primary
charged particles are measured in the pseudo-rapidity range as a
function of event centrality in Pb-Pb collisions at
TeV with ALICE at the LHC. The data are presented in the range
GeV/ for nine centrality intervals from 70-80% to 0-5%.
The Pb-Pb spectra are presented in terms of the nuclear modification factor
using a pp reference spectrum measured at the same collision
energy. We observe that the suppression of high- particles strongly
depends on event centrality. In central collisions (0-5%) the yield is most
suppressed with at -7 GeV/. Above
GeV/, there is a significant rise in the nuclear modification
factor, which reaches for GeV/. In
peripheral collisions (70-80%), the suppression is weaker with almost independently of . The measured nuclear
modification factors are compared to other measurements and model calculations.Comment: 17 pages, 4 captioned figures, 2 tables, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/284
Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at TeV
The elliptic, , triangular, , and quadrangular, , azimuthal
anisotropic flow coefficients are measured for unidentified charged particles,
pions and (anti-)protons in Pb-Pb collisions at TeV
with the ALICE detector at the Large Hadron Collider. Results obtained with the
event plane and four-particle cumulant methods are reported for the
pseudo-rapidity range at different collision centralities and as a
function of transverse momentum, , out to GeV/.
The observed non-zero elliptic and triangular flow depends only weakly on
transverse momentum for GeV/. The small dependence
of the difference between elliptic flow results obtained from the event plane
and four-particle cumulant methods suggests a common origin of flow
fluctuations up to GeV/. The magnitude of the (anti-)proton
elliptic and triangular flow is larger than that of pions out to at least
GeV/ indicating that the particle type dependence persists out
to high .Comment: 16 pages, 5 captioned figures, authors from page 11, published
version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186
Measurement of charm production at central rapidity in proton-proton collisions at TeV
The -differential production cross sections of the prompt (B
feed-down subtracted) charmed mesons D, D, and D in the rapidity
range , and for transverse momentum GeV/, were
measured in proton-proton collisions at TeV with the ALICE
detector at the Large Hadron Collider. The analysis exploited the hadronic
decays DK, DK, DD, and their charge conjugates, and was performed on a
nb event sample collected in 2011 with a
minimum-bias trigger. The total charm production cross section at TeV and at 7 TeV was evaluated by extrapolating to the full phase space
the -differential production cross sections at TeV
and our previous measurements at TeV. The results were compared
to existing measurements and to perturbative-QCD calculations. The fraction of
cdbar D mesons produced in a vector state was also determined.Comment: 20 pages, 5 captioned figures, 4 tables, authors from page 15,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/307
SARS-CoV-2 viral load in nasopharyngeal swabs is not an independent predictor of unfavorable outcome
The aim was to assess the ability of nasopharyngeal SARS-CoV-2 viral load at first patient’s hospital evaluation to predict unfavorable outcomes. We conducted a prospective cohort study including 321 adult patients with confirmed COVID-19 through RT-PCR in nasopharyngeal swabs. Quantitative Synthetic SARS-CoV-2 RNA cycle threshold values were used to calculate the viral load in log10 copies/mL. Disease severity at the end of follow up was categorized into mild, moderate, and severe. Primary endpoint was a composite of intensive care unit (ICU) admission and/or death (n = 85, 26.4%). Univariable and multivariable logistic regression analyses were performed. Nasopharyngeal SARS-CoV-2 viral load over the second quartile (≥ 7.35 log10 copies/mL, p = 0.003) and second tertile (≥ 8.27 log10 copies/mL, p = 0.01) were associated to unfavorable outcome in the unadjusted logistic regression analysis. However, in the final multivariable analysis, viral load was not independently associated with an unfavorable outcome. Five predictors were independently associated with increased odds of ICU admission and/or death: age ≥ 70 years, SpO2, neutrophils > 7.5 × 103/µL, lactate dehydrogenase ≥ 300 U/L, and C-reactive protein ≥ 100 mg/L. In summary, nasopharyngeal SARS-CoV-2 viral load on admission is generally high in patients with COVID-19, regardless of illness severity, but it cannot be used as an independent predictor of unfavorable clinical outcome
Dendritic cell deficiencies persist seven months after SARS-CoV-2 infection
Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV)-2 infection induces an exacerbated inflammation driven by innate immunity components. Dendritic cells (DCs) play a key role in the defense against viral infections, for instance plasmacytoid DCs (pDCs), have the capacity to produce vast amounts of interferon-alpha (IFN-α). In COVID-19 there is a deficit in DC numbers and IFN-α production, which has been associated with disease severity. In this work, we described that in addition to the DC deficiency, several DC activation and homing markers were altered in acute COVID-19 patients, which were associated with multiple inflammatory markers. Remarkably, previously hospitalized and nonhospitalized patients remained with decreased numbers of CD1c+ myeloid DCs and pDCs seven months after SARS-CoV-2 infection. Moreover, the expression of DC markers such as CD86 and CD4 were only restored in previously nonhospitalized patients, while no restoration of integrin β7 and indoleamine 2,3-dyoxigenase (IDO) levels were observed. These findings contribute to a better understanding of the immunological sequelae of COVID-19
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