500 research outputs found
The Higgs - photon - Z boson coupling revisited
We analyze the coupling of CP-even and CP-odd Higgs bosons to a photon and a
Z boson in extensions of the Standard Model. In particular, we study in detail
the effect of charged Higgs bosons in two-Higgs doublet models, and the
contribution of SUSY particle loops in the minimal supersymmetric extension of
the Standard Model. The Higgs- coupling can be measured in the decay
+Higgs at colliders running on the Z resonance, or in
the reverse process Higgs with the Higgs boson produced at LHC.
We show that a measurement of this coupling with a precision at the percent
level, which could be the case at future colliders, would allow to
distinguish between the lightest SUSY and standard Higgs bosons in large areas
of the parameter space.Comment: 18 pages LaTex + 7 figures (ps). Typo corrected in eq.(5
Positive culture in allograft ACL-reconstruction: what to do?
The transmission of disease or infection from the donor to the recipient is always a risk with the use of allografts. We carried out a research study on the behavioural pattern of implanted allografts, which were initially stored in perfect conditions (all cultures being negative) but later presented positive cultures at the implantation stage. Because there is no information available on how to deal with this type of situation, our aim was to set guidelines on the course of action which would be required in such a case. We conducted a retrospective study of 181 patients who underwent an ACL reconstruction using BPTB allografts. All previous bone and blood cultures and tests for hepatitis B and C, syphilis and HIV were negative. An allograft sample was taken for culture in the operating theatre just before its implantation. The results of the cultures were obtained 3-5 days after the operation. We had 24 allografts with positive culture (13.25%) after the implantation with no clinical infection in any of these patients. Positive cultures could be caused by undetected contamination while harvesting, storing or during manipulation before implantation. The lack of clinical signs of infection during the follow-up of our patients may indicate that no specific treatment-other than an antibiotic protocol-would be required when facing a case of positive culture of a graft piece after its implantation
Atmospheric effects on extensive air showers observed with the Surface Detector of the Pierre Auger Observatory
Atmospheric parameters, such as pressure (P), temperature (T) and density,
affect the development of extensive air showers initiated by energetic cosmic
rays. We have studied the impact of atmospheric variations on extensive air
showers by means of the surface detector of the Pierre Auger Observatory. The
rate of events shows a ~10% seasonal modulation and ~2% diurnal one. We find
that the observed behaviour is explained by a model including the effects
associated with the variations of pressure and density. The former affects the
longitudinal development of air showers while the latter influences the Moliere
radius and hence the lateral distribution of the shower particles. The model is
validated with full simulations of extensive air showers using atmospheric
profiles measured at the site of the Pierre Auger Observatory.Comment: 24 pages, 9 figures, accepted for publication in Astroparticle
Physic
Update on the correlation of the highest energy cosmic rays with nearby extragalactic matter
Data collected by the Pierre Auger Observatory through 31 August 2007 showed
evidence for anisotropy in the arrival directions of cosmic rays above the
Greisen-Zatsepin-Kuz'min energy threshold, \nobreak{eV}. The
anisotropy was measured by the fraction of arrival directions that are less
than from the position of an active galactic nucleus within 75 Mpc
(using the V\'eron-Cetty and V\'eron catalog). An updated
measurement of this fraction is reported here using the arrival directions of
cosmic rays recorded above the same energy threshold through 31 December 2009.
The number of arrival directions has increased from 27 to 69, allowing a more
precise measurement. The correlating fraction is , compared
with expected for isotropic cosmic rays. This is down from the early
estimate of . The enlarged set of arrival directions is
examined also in relation to other populations of nearby extragalactic objects:
galaxies in the 2 Microns All Sky Survey and active galactic nuclei detected in
hard X-rays by the Swift Burst Alert Telescope. A celestial region around the
position of the radiogalaxy Cen A has the largest excess of arrival directions
relative to isotropic expectations. The 2-point autocorrelation function is
shown for the enlarged set of arrival directions and compared to the isotropic
expectation.Comment: Accepted for publication in Astroparticle Physics on 31 August 201
Efficacy of pre-emergence herbicides in controlling Sumatran fleabane (Conyza sumatrensis) in the off-season
Received: February 1st, 2023 ; Accepted: May 7th, 2023 ; Published: May 19th, 2023 ;
Correspondence: [email protected] herbicides can be effective in controlling Sumatran fleabane
(Conyza sumatrensis [Retz.] E.Walker) at soybean and other crops. The goal was to evaluate the
effectiveness of sulfentrazone/diuron, imazethapyr/flumioxazin, flumioxazin, diclosulam,
s-metolachlor, imazethapyr, clomazone and imazapic/imazapyr in controlling Sumatran fleabane
for application in the off-season before soybean planting. Three experiments were conducted in
the off season, with 9 treatments. The control of Sumatran fleabane was evaluated at 28, 42
and 49 days after application (DAA), at 49 DAA was performed counting of plants per m2
. In
experiment 1, the worst performance was found for s-metolachlor (58.3% final control), in a
situation of lower emergence flow of Sumatran fleabane, with equivalence for the other
herbicides. In experiments 2 and 3, with greater emergence flow of Sumatran fleabane,
clomazone efficacy stood out (≥ 86.3% final control). A micro-encapsulated formulation of
clomazone was used, which causes greater intoxication to this weed due to its slow release into
the soil, and presents less loss to the environment. In conditions of lower emergence of Sumatran
fleabane, sulfentrazone/diuron, imazethapyr/flumioxazin, flumioxazin, diclosulam, imazethapyr,
clomazone and imazapic/imazapyr were effective in controlling it. Even in this condition,
s-metolachlor was not effective in controlling Sumatran fleabane. The application of clomazone
was effective in controlling Sumatran fleabane in the three experiments. Clomazone is
characterized as an important herbicide for use in the off season in the management of this weed
before soybean sowing
The Fluorescence Detector of the Pierre Auger Observatory
The Pierre Auger Observatory is a hybrid detector for ultra-high energy
cosmic rays. It combines a surface array to measure secondary particles at
ground level together with a fluorescence detector to measure the development
of air showers in the atmosphere above the array. The fluorescence detector
comprises 24 large telescopes specialized for measuring the nitrogen
fluorescence caused by charged particles of cosmic ray air showers. In this
paper we describe the components of the fluorescence detector including its
optical system, the design of the camera, the electronics, and the systems for
relative and absolute calibration. We also discuss the operation and the
monitoring of the detector. Finally, we evaluate the detector performance and
precision of shower reconstructions.Comment: 53 pages. Submitted to Nuclear Instruments and Methods in Physics
Research Section
Search for First Harmonic Modulation in the Right Ascension Distribution of Cosmic Rays Detected at the Pierre Auger Observatory
We present the results of searches for dipolar-type anisotropies in different
energy ranges above eV with the surface detector array of
the Pierre Auger Observatory, reporting on both the phase and the amplitude
measurements of the first harmonic modulation in the right-ascension
distribution. Upper limits on the amplitudes are obtained, which provide the
most stringent bounds at present, being below 2% at 99% for EeV
energies. We also compare our results to those of previous experiments as well
as with some theoretical expectations.Comment: 28 pages, 11 figure
Techniques for measuring aerosol attenuation using the Central Laser Facility at the Pierre Auger Observatory
The Pierre Auger Observatory in Malargüe, Argentina, is designed to study the properties of ultra-high energy cosmic rays with energies above 10(18) eV. It is a hybrid facility that employs a Fluorescence Detector to perform nearly calorimetric measurements of Extensive Air Shower energies. To obtain reliable calorimetric information from the FD, the atmospheric conditions at the observatory need to be continuously monitored during data acquisition. In particular, light attenuation due to aerosols is an important atmospheric correction. The aerosol concentration is highly variable, so that the aerosol attenuation needs to be evaluated hourly. We use light from the Central Laser Facility, located near the center of the observatory site, having an optical signature comparable to that of the highest energy showers detected by the FD. This paper presents two procedures developed to retrieve the aerosol attenuation of fluorescence light from CLF laser shots. Cross checks between the two methods demonstrate that results from both analyses are compatible, and that the uncertainties are well understood. The measurements of the aerosol attenuation provided by the two procedures are currently used at the Pierre Auger Observatory to reconstruct air shower data
Prediction of Pathological Tremor Signals Using Long Short-Term Memory Neural Networks
Previous implementations of closed-loop peripheral electrical stimulation (PES) strategies have provided evidence about the effect of the stimulation timing on tremor reduction. However, these strategies have used traditional signal processing techniques that only consider phase prediction and might not model the non-stationary behavior of tremor. Here, we tested the use of long short-term memory (LSTM) neural networks to predict tremor signals using kinematic data recorded from Essential Tremor (ET) patients. A dataset comprising wrist flexion-extension data from 12 ET patients was pre-processed to feed the predictors. A total of 180 models resulting from the combination of network (neurons and layers of the LSTM networks, length of the input sequence and prediction horizon) and training parameters (learning rate) were trained, validated and tested. Predicted tremor signals using LSTM-based models presented high correlation values (from 0.709 to 0.998) with the expected values, with a phase delay between the predicted and real signals below 15 ms, which corresponds approximately to 7.5% of a tremor cycle. The prediction horizon was the parameter with a higher impact on the prediction performance. The proposed LSTM-based models were capable of predicting both phase and amplitude of tremor signals outperforming results from previous studies (32 - 56% decreased phase prediction error compared to the out-of-phase method), which might provide a more robust PES-based closed-loop control applied to PES-based tremor reduction.The authors would like to thank Cristina Montero Pardo for illustrations from Fig. 1 and the patients from Gregorio Marañón Hospital who voluntarily participated in this study
Leukopenia in Kidney Transplant Patients With the Association of Valganciclovir and Mycophenolate Mofetil
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