262 research outputs found
New type of ensemble of quasi-periodic, long-lasting VLF emissions at the auroral zone
A new type of the series of quasi-periodic (QP) very low
frequency (VLF) emissions in frequency range of 1–5 kHz, and not associated
with geomagnetic pulsations, has been discovered at auroral latitudes
(<I>L</I> = 5.3) during the Finnish VLF campaign (held in December 2011). At least
five unusually spectacular events, each with a duration of several hours,
have been observed during the night under conditions of quiet geomagnetic
activity (Kp = 0–1), although QPs usually occur during the daytime. Contrary
to the QP emissions typically occurring during the day, the spectral
structure of these QP events represented an extended, complicated sequence
of repeated discrete rising VLF signals. Their duration was about 2–3 min
each, with the repetition periods ranging from ~1 min to
~10 min. Two such nighttime non-typical events are reported
in this paper. The fine structure of the separated QP elements may represent
a mixture of the different frequency band signals, which seem to have
independent origins. It was found that the periodic signals with lower
frequency appear to trigger the strong dispersive upper frequency
signals. The temporal dynamics of the spectral
structure of the QPs studied were significantly controlled by some
disturbances in the solar wind and interplanetary magnetic field (IMF). This finding is very important for
future theoretical investigations because the generation mechanism of this
new type of QP emissions is not yet understood
Unusual strong quasi-monochromatic ground Pc5 geomagnetic pulsations in the recovery phase of November 2003 superstorm
New results of structured VLF emissions observed simultaneously at two closely located stations near <i>L</i> ~ 5.5
Influence of critical hypotension on the development of postoperative hepatic failure
The article is devoted to the study of influence of critical hypotension on the development of postoperative hepatic failure. The results of treatment of 54 patients who had. anatomical and advanced anatomical resections of a liver were analyzed. Also the causes that lead to the postoperative hepatic failure such as volume of intraoperative blood loss, duration of intraoperative hypotension were analyzed. As the result of the analysis of obtained data on the influence of studied parameters (volume of blood loss, duration. of vascular isolation and presence of intraoperative hypotension) on the development of hepatic failure in postoperative period we supposed that the most unfavorable prognostic sign of its appearance is an episode of critical decrease of arterial pressure during the operation. Thus even at massive blood loss hepatic failure doesn't always appear, whereas critical intraoperative hypotension causes its development. Taking into consideration data on the state of central hemodynamics at the performing of anatomic resections of liver we determined main approaches to the infusion-transfusion therapy during excluding of liver from blood circulation for the prophylactics of its reperfusion injuries. It was established that prophylactics and timely correction of critical intraoperative hypotenstion that is the main factor of development of postoperative hepatic failure should be considered as the key moments of intraoperative protection of hepatocytes
Performance of the NA62 trigger system
The NA62 experiment at CERN targets the measurement of the ultra-rare
K+ ->pi+ nu nu decay, and carries out a broad physics programme that includes probes for
symmetry violations and searches for exotic particles. Data were collected in 2016–2018
using a multi-level trigger system, which is described highlighting performance studies
based on 2018 data
Externalities and the nucleolus
In most economic applications, externalities prevail: the worth of a coalition depends on how the other players are organized. We show that there is a unique natural way of extending the nucleolus from (coalitional) games without externalities to games with externalities. This is in contrast to the Shapley value and the core for which many different extensions have been proposed
Physics beyond the standard model with kaons at NA62
The NA62 experiment at CERN Super Proton Synchrotron was designed to measure BR(K+ \u2192 \u3c0+\u3bdv\u304) with an in-fight technique, never used before for this measurement. This decay is characterised by a very precise prediction in the Standard Model. Its branching ratio, which is expected to be less than 10-10, is one of the best candidates to indicate indirect effects of new physics beyond SM at the highest mass scales. NA62 result on K+ \u2192 \u3c0+\u3bdv\u304 from the full 2016 data set is described. Also a search for an invisible dark photon A\u2032 has been performed, exploiting the efficient photon-veto capability and high resolution tracking of the NA62. The signal stems from the chain K+ \u2192 \u3c0+\u3c00 followed by \u3c00 \u2192 A\u2032\u3b3. No significant statistical excess has been identified. Upper limits on the dark photon coupling to the ordinary photon as a function of the dark photon mass have been set, improving on the previous limits over the mass range 60 - 110 MeV/c2
Searches for lepton number violating K+ decays
The NA62 experiment at CERN reports a search for the lepton number violating decays K+→π−e+e+ and K+→π−μ+μ+ using a data sample collected in 2017. No signals are observed, and upper limits on the branching fractions of these decays of 2.2 x 10^-10 and 4.2 x 10^-11 are obtained, respectively, at 90% confidence level. These upper limits improve on previously reported measurements by factors of 3 and 2, respectively
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