110 research outputs found
Hydronephrosis in a Dog Related to Ovariosalpingohysterectomy
Background: Hydronephrosis is the dilation of the pelvis and renal calyxes due to post-renal obstruction. The obstruction is often associated with extraluminal masses, blood clots and ureter ligation in castration procedures. Ureter ligation is reported as a malpractice. The renal function is reestablished if ligation is rapidly undone, but not for obstructions longer than four weeks. Often, clinical signs are results from months to years after the castration, when nephrectomy is the best therapeutic option. This paper aims to report a case of asymptomatic unilateral hydronephrosis in a 10-year-old dog caused by chronic ureter occlusion with Nylon 3.0 suture during an elective procedure.Case: A 10-year-old female pinscher dog, spayed 3 years ago was admitted at the Surgery Department of the Veterinary Hospital of the Federal University of Jataí (HV-UFJ). The animal was taken for periodontal treatment. In the physical and laboratory examination (complete blood count, hepatic and renal biochemical tests) no significant and noteworthy alterations were found. Ultrasonographic examination showed no changes in the topography and echotexture of the left kidney, however the right kidney was not visualized, with an anechoic structure suggestive of advanced and severe hydronephrosis. Therefore, exploratory laparotomy was proposed to identify the observed structure, with the periodontal treatment considered for a later time. So, a retroumbilical incision was made, followed by linea alba and the removal of simple isolated suture remaining from previous surgical procedure. In the cavity, the viscera were isolated and the left kidney was identified, observing preserved anatomy. On the other hand, the right kidney had altered topography and morphology, being exposed after release of adhesions in adjacent structures. The right renal artery and vein were dissected and a double ligature was made. Then, the right ureter was dissected, observing marked dilatation in the proximal portion and the presence of local ligation with Nylon 3.0. Right ureterectomy and right nephrectomy were performed. After nephrectomy, the capsule was ruptured, observing dark fluid in it and absence of tissue compatible with renal parenchyma. The material was preserved in 10% formaldehyde and sent for histopathological examination. Histopathology revealed risk of rupture of the renal capsule due to the advance of renal degeneration and complete absence of parenchyma. However, contrary to the severity of the histopathological, surgical and ultrasonographic findings, the patient did not present clinical signs at the time of diagnosis.Discussion: In the intraoperative evaluation, the cause of the hydronephrosis was verified to be in fact the ligation of the ureter, which may have been accidental or due to the malpractice of the veterinarian surgeon. Other possible causes such as adhesions and granulomas were ruled out because the Nylon 3.0 suture was found in the proximal portion of the right ureter. It is believed that the patient may have presented clinical signs of hydronephrosis that may have been confused by the tutors as postoperative complications, changes that if identified and performed in time, could have avoided the occurrence or worsening of hydronephrosis and subsequent nephrectomy. Clinically, the bitch did not show clinical signs presented in the literature as consistent with hydronephrosis such as polyuria, polydipsia, abdominalgia, external fistula and anorexia. Therefore, it is believed that this case is one of the first reports of the occurrence of severe hydronephrosis without typical clinical manifestations of hydronephrosis. This fact raises a warning about the thorough monitoring in the postoperative period by owners and veterinarians, in addition to highlighting concerns regarding the occurrence of medical malpractice versus surgical accidents. Keywords: castration, malpractice, nephrectomy, nylon
Measurement of the cosmic ray spectrum above eV using inclined events detected with the Pierre Auger Observatory
A measurement of the cosmic-ray spectrum for energies exceeding
eV is presented, which is based on the analysis of showers
with zenith angles greater than detected with the Pierre Auger
Observatory between 1 January 2004 and 31 December 2013. The measured spectrum
confirms a flux suppression at the highest energies. Above
eV, the "ankle", the flux can be described by a power law with
index followed by
a smooth suppression region. For the energy () at which the
spectral flux has fallen to one-half of its extrapolated value in the absence
of suppression, we find
eV.Comment: Replaced with published version. Added journal reference and DO
Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory
The Auger Engineering Radio Array (AERA) is part of the Pierre Auger
Observatory and is used to detect the radio emission of cosmic-ray air showers.
These observations are compared to the data of the surface detector stations of
the Observatory, which provide well-calibrated information on the cosmic-ray
energies and arrival directions. The response of the radio stations in the 30
to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of
the incoming electric field. For the latter, the energy deposit per area is
determined from the radio pulses at each observer position and is interpolated
using a two-dimensional function that takes into account signal asymmetries due
to interference between the geomagnetic and charge-excess emission components.
The spatial integral over the signal distribution gives a direct measurement of
the energy transferred from the primary cosmic ray into radio emission in the
AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air
shower arriving perpendicularly to the geomagnetic field. This radiation energy
-- corrected for geometrical effects -- is used as a cosmic-ray energy
estimator. Performing an absolute energy calibration against the
surface-detector information, we observe that this radio-energy estimator
scales quadratically with the cosmic-ray energy as expected for coherent
emission. We find an energy resolution of the radio reconstruction of 22% for
the data set and 17% for a high-quality subset containing only events with at
least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO
Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy
We measure the energy emitted by extensive air showers in the form of radio
emission in the frequency range from 30 to 80 MHz. Exploiting the accurate
energy scale of the Pierre Auger Observatory, we obtain a radiation energy of
15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV
arriving perpendicularly to a geomagnetic field of 0.24 G, scaling
quadratically with the cosmic-ray energy. A comparison with predictions from
state-of-the-art first-principle calculations shows agreement with our
measurement. The radiation energy provides direct access to the calorimetric
energy in the electromagnetic cascade of extensive air showers. Comparison with
our result thus allows the direct calibration of any cosmic-ray radio detector
against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI.
Supplemental material in the ancillary file
The second knee in the cosmic ray spectrum observed with the surface detector of the Pierre Auger Observatory
Combined fit to the spectrum and composition data measured by the Pierre Auger Observatory including magnetic horizon effects
The measurements by the Pierre Auger Observatory of the energy spectrum and mass composition of cosmic rays can be interpreted assuming the presence of two extragalactic source populations, one dominating the flux at energies above a few EeV and the other below. To fit the data ignoring magnetic field effects, the high-energy population needs to accelerate a mixture of nuclei with very hard spectra, at odds with the approximate E shape expected from diffusive shock acceleration. The presence of turbulent extragalactic magnetic fields in the region between the closest sources and the Earth can significantly modify the observed CR spectrum with respect to that emitted by the sources, reducing the flux of low-rigidity particles that reach the Earth. We here take into account this magnetic horizon effect in the combined fit of the spectrum and shower depth distributions, exploring the possibility that a spectrum for the high-energy population sources with a shape closer to E be able to explain the observations
Extraction of the Muon Signals Recorded with the Surface Detector of the Pierre Auger Observatory Using Recurrent Neural Networks
We present a method based on the use of Recurrent Neural Networks to extract the muon component from the time traces registered with water-Cherenkov detector (WCD) stations of the Surface Detector of the Pierre Auger Observatory. The design of the WCDs does not allow to separate the contribution of muons to the time traces obtained from the WCDs from those of photons, electrons and positrons for all events. Separating the muon and electromagnetic components is crucial for the determination of the nature of the primary cosmic rays and properties of the hadronic interactions at ultra-high energies.
We trained a neural network to extract the muon and the electromagnetic components from the WCD traces using a large set of simulated air showers, with around 450 000 simulated events. For training and evaluating the performance of the neural network, simulated events with energies between 1018.5, eV and 1020 eV and zenith angles below 60 degrees were used. We also study the performance of this method on experimental data of the Pierre Auger Observatory and show that our predicted muon lateral distributions agree with the parameterizations obtained by the AGASA collaboration
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