Os docentes e avaliaçao da aprendizagem: um estudio na licenciatura en analises clínicas e saude pública

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A induçao de fibrilaçao atrial nao sustentada pré-implante constitui-se em critério para a nao utilizaçao da estimulaçao atrial definitiva?

Este trabalho visa correlacionar a incidência de fibrilaçao atrial (FA) com os critérios para escolha do modo de estimulaçao cardíaca definitiva. Foi realizado um estudo prospectivo de 44 pacientes consecutivos, submetidos a implante de marcapasso com a estimulaçao atrial definitiva (EAD). As indicaçoes para o implante foram: disfunçao do nó sinusal em 20 pacientes, BAV 3º grau em 11 pacientes, BAV de 2º grau em 7 pacientes, taquicardia paroxística supra-ventricular em 3 pacientes, hipersensibilidade do seio carotídeo em 2 pacientes e síncope vaso-vagal em 1 paciente. O modo de estimulaçao utilizado foi AAI (47,7%) e DDD (48,7%) e, em todos os casos, a estimulaçao foi feita com cabo-eletrodo de fixaçao ativa. O tempo médio de seguimento foi de 47,8 meses. Antes do implante do marcapasso os pacientes foram submetidos a testes de avaliaçao do sistema juncional AV (determinaçao do ponto de Wenckebach) e estabilidade atrial, com estimulaçao atrial transesofágica ou intra-cavitária, sendo selecionados para implante com EAD apenas apacientes que apresentaram fibrilaçao atrial nao sustentada (FANS) ou átrio estável. Dos 44 pacientes estudados, 4 apresentaram FANS durante os testes. Destes, 1 paciente desenvolveu FA crônica, tornando desnecessária a EAD, e outro apresentou episódios repetidos de FA, revertidos ao ritmo sinusal com amiodarona. Os outros 2 pacientes ainda estao em seguimento sem apresentar fibrilaçao atrial. Considerase que: 1 - o marcapasso com EAD associa-se a uma baixa incidência de FA no pós-operatório; 2 - a necessidade de alterar o modo de estimulaçao é mínima quando sao observados os resultados dos testes pré-operatórios; 3 - a induçao da FANS no pré-operatório parece indicar que o paciente irá desenvolver FA durante a evoluçao, o que nao impede que se proceda a EAD, mesmo que por um período de tempo limitado

Reduced expression of mir15a in the blood of patients with oral squamous cell carcinoma is associated with tumor staging

MicroRNAs (miRNAs) mirl 5a and let7a are iMportant regulators of bcl-2, ras and c-myc proteins Considering that these miRNAs are commonly altered in many human cancers and that these proteins are reported to be altered in oral squamous cell carcinoma (OSCC), we investigated them in a set of OSCC cases \u27I he miRNAs as well as the proteins were evaluated in the tumor and blood of 20 patients by real-time quantitative PCR and iMmunohistochemistry, respectively The expression of nfirl5a and bcl-2 proteins in the tumors was not associated with each other or with tumor staging On the other hand, we found reduced expression of this miRNA in the blood of patients with an advanced stage of OSCC and with lymph node metastasis The expression of let7a in the tumor and blood was not associated with tumor size lymph node metastasis, tumor staging and immunoexpression of ras and c-myc proteins In conclusion, the present study shows that reduced expression of Mir15a is associated with OSCC stagin

Testing Hadronic Interactions at Ultrahigh Energies with Air Showers Measured by the Pierre Auger Observatory

Ultrahigh energy cosmic ray air showers probe particle physics at energies beyond the reach of accelerators. Here we introduce a new method to test hadronic interaction models without relying on the absolute energy calibration, and apply it to events with primary energy 6-16 EeV (E_CM = 110-170 TeV), whose longitudinal development and lateral distribution were simultaneously measured by the Pierre Auger Observatory. The average hadronic shower is 1.33 +- 0.16 (1.61 +- 0.21) times larger than predicted using the leading LHC-tuned models EPOS-LHC (QGSJetII-04), with a corresponding excess of muons.Peer Reviewe

Azimuthal Asymmetry in the Risetime of the Surface Detector Signals of the Pierre Auger Observatory

The azimuthal asymmetry in the risetime of signals in Auger surface detector stations is a source of information on shower development. The azimuthal asymmetry is due to a combination of the longitudinal evolution of the shower and geometrical effects related to the angles of incidence of the particles into the detectors. The magnitude of the effect depends upon the zenith angle and state of development of the shower and thus provides a novel observable, (secθ)max, sensitive to the mass composition of cosmic rays above 3×1018  eV. By comparing measurements with predictions from shower simulations, we find for both of our adopted models of hadronic physics (QGSJETII-04 and EPOS-LHC) an indication that the mean cosmic-ray mass increases slowly with energy, as has been inferred from other studies. However, the mass estimates are dependent on the shower model and on the range of distance from the shower core selected. Thus the method has uncovered further deficiencies in our understanding of shower modeling that must be resolved before the mass composition can be inferred from (secθ)max.Peer Reviewe

Antennas for the Detection of Radio Emission Pulses from Cosmic-Ray

The Pierre Auger Observatory is exploring the potential of the radio detection technique to study extensive air showers induced by ultra-high energy cosmic rays. The Auger Engineering Radio Array (AERA) addresses both technological and scientific aspects of the radio technique. A first phase of AERA has been operating since September 2010 with detector stations observing radio signals at frequencies between 30 and 80 MHz. In this paper we present comparative studies to identify and optimize the antenna design for the final configuration of AERA consisting of 160 individual radio detector stations. The transient nature of the air shower signal requires a detailed description of the antenna sensor. As the ultra-wideband reception of pulses is not widely discussed in antenna literature, we review the relevant antenna characteristics and enhance theoretical considerations towards the impulse response of antennas including polarization effects and multiple signal reflections. On the basis of the vector effective length we study the transient response characteristics of three candidate antennas in the time domain. Observing the variation of the continuous galactic background intensity we rank the antennas with respect to the noise level added to the galactic signal.Peer Reviewe

Improved limit to the diffuse flux of ultrahigh energy neutrinos from the Pierre Auger Observatory

Neutrinos in the cosmic ray flux with energies near 1 EeV and above are detectable with the Surface Detector array (SD) of the Pierre Auger Observatory. We report here on searches through Auger data from 1 January 2004 until 20 June 2013. No neutrino candidates were found, yielding a limit to the diffuse flux of ultrahigh energy neutrinos that challenges the Waxman-Bahcall bound predictions. Neutrino identification is attempted using the broad time structure of the signals expected in the SD stations, and is efficiently done for neutrinos of all flavors interacting in the atmosphere at large zenith angles, as well as for “Earth-skimming” neutrino interactions in the case of tau neutrinos. In this paper the searches for downward-going neutrinos in the zenith angle bins 60°–75° and 75°–90° as well as for upward-going neutrinos, are combined to give a single limit. The 90% C.L. single-flavor limit to the diffuse flux of ultrahigh energy neutrinos with an E-2 spectrum in the energy range 1.0×1017  eV–2.5×1019  eV is Eν2dNν/dEν<6.4×10−9  GeV cm−2 s−1 sr−1.Peer Reviewe

Nanosecond-level time synchronization of autonomous radio detector stations for extensive air showers

To exploit the full potential of radio measurements of cosmic-ray air showers at MHz frequencies, a detector timing synchronization within 1 ns is needed. Large distributed radio detector arrays such as the Auger Engineering Radio Array (AERA) rely on timing via the Global Positioning System (GPS) for the synchronization of individual detector station clocks. Unfortunately, GPS timing is expected to have an accuracy no better than about 5 ns. In practice, in particular in AERA, the GPS clocks exhibit drifts on the order of tens of ns. We developed a technique to correct for the GPS drifts, and an independent method is used to cross-check that indeed we reach a nanosecond-scale timing accuracy by this correction. First, we operate a ``beacon transmitter'' which emits defined sine waves detected by AERA antennas recorded within the physics data. The relative phasing of these sine waves can be used to correct for GPS clock drifts. In addition to this, we observe radio pulses emitted by commercial airplanes, the position of which we determine in real time from Automatic Dependent Surveillance Broadcasts intercepted with a software-defined radio. From the known source location and the measured arrival times of the pulses we determine relative timing offsets between radio detector stations. We demonstrate with a combined analysis that the two methods give a consistent timing calibration with an accuracy of 2 ns or better. Consequently, the beacon method alone can be used in the future to continuously determine and correct for GPS clock drifts in each individual event measured by AERA.Peer Reviewe

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 30–80 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.Peer Reviewe