619 research outputs found
Semantic change in portuguese: Considering cerrado and vereda
© 2020, Universiti Kebangsaan Malaysia Press. All rights reserved. This paper highlights the process by which meaning instantiates itself in word formation and discusses how semantic change installs subsequently in them, in this case, the Portuguese words cerrado and vereda. These two words have long individual histories that can be tracked back to their Latin or Celtic etymons, cerrado rooted in the origin of the Latin verb serÄre, which gave origin to the Portuguese verb cerrar (to close, to seal) and vereda (narrow path) derived from the Latin word veredus (horse), which has its root in the Celtic word voredos. Yet, in the modern Brazilian context, Cerrado designates a particular ecosystem, the second largest biome in the country, that of short, closely-packed trees and foliage, and Vereda, a verdant subsystem of the same ecosystem. The discussion tracks the linguistic movement to arrive at these current meanings, showing how understanding the âhistoryâ of a word helps to understand both the uniqueness of its morpho-phonological and semantic constitution, as well as that of its relationship with the object it designates in the empirical world
Performance of the ABCN-25 readout chip for the ATLAS Inner Detector Upgrade
We present the test results of the ABCN-25 front end chip implemented in CMOS 0.25 ÎŒm technology and optimised for the short, 2.5 cm, silicon strips intended to be used in the upgrade of the ATLAS Inner Detector. We have obtained the full functionality of the readout part, the expected performance of the analogue front-end and the operation of the power control circuits. The performance is evaluated in view of the minimization of the power consumption, as the upgrade detector may contain up to 70 million of channels. System tests with different power distribution schemes proposed for the future tracker detectors are possible with this chip. The ABCN-25 ASIC is now serving as the prototype readout chip in the developments of the modules and staves for the upgrade of the ATLAS Inner Detector
Internal alignment and position resolution of the silicon tracker of DAMPE determined with orbit data
The DArk Matter Particle Explorer (DAMPE) is a space-borne particle detector
designed to probe electrons and gamma-rays in the few GeV to 10 TeV energy
range, as well as cosmic-ray proton and nuclei components between 10 GeV and
100 TeV. The silicon-tungsten tracker-converter is a crucial component of
DAMPE. It allows the direction of incoming photons converting into
electron-positron pairs to be estimated, and the trajectory and charge (Z) of
cosmic-ray particles to be identified. It consists of 768 silicon micro-strip
sensors assembled in 6 double layers with a total active area of 6.6 m.
Silicon planes are interleaved with three layers of tungsten plates, resulting
in about one radiation length of material in the tracker. Internal alignment
parameters of the tracker have been determined on orbit, with non-showering
protons and helium nuclei. We describe the alignment procedure and present the
position resolution and alignment stability measurements
Reconstruction of the Dark Energy equation of state
One of the main challenges of modern cosmology is to investigate the nature
of dark energy in our Universe. The properties of such a component are normally
summarised as a perfect fluid with a (potentially) time-dependent
equation-of-state parameter . We investigate the evolution of this
parameter with redshift by performing a Bayesian analysis of current
cosmological observations. We model the temporal evolution as piecewise linear
in redshift between `nodes', whose -values and redshifts are allowed to
vary. The optimal number of nodes is chosen by the Bayesian evidence. In this
way, we can both determine the complexity supported by current data and locate
any features present in . We compare this node-based reconstruction with
some previously well-studied parameterisations: the Chevallier-Polarski-Linder
(CPL), the Jassal-Bagla-Padmanabhan (JBP) and the Felice-Nesseris-Tsujikawa
(FNT). By comparing the Bayesian evidence for all of these models we find an
indication towards possible time-dependence in the dark energy
equation-of-state. It is also worth noting that the CPL and JBP models are
strongly disfavoured, whilst the FNT is just significantly disfavoured, when
compared to a simple cosmological constant . We find that our node-based
reconstruction model is slightly disfavoured with respect to the CDM
model.Comment: 17 pages, 5 figures, minor correction
A double-sided silicon micro-strip super-module for the ATLAS inner detector upgrade in the high-luminosity LHC
The ATLAS experiment is a general purpose detector aiming to fully exploit the discovery potential of the Large Hadron Collider (LHC) at CERN. It is foreseen that after several years of successful data-taking, the LHC physics programme will be extended in the so-called High-Luminosity LHC, where the instantaneous luminosity will be increased up to 5 Ă 1034 cmâ2 sâ1. For ATLAS, an upgrade scenario will imply the complete replacement of its internal tracker, as the existing detector will not provide the required performance due to the cumulated radiation damage and the increase in the detector occupancy. The current baseline layout for the new ATLAS tracker is an all-silicon-based detector, with pixel sensors in the inner layers and silicon micro-strip detectors at intermediate and outer radii. The super-module is an integration concept proposed for the strip region of the future ATLAS tracker, where double-sided stereo silicon micro-strip modules are assembled into a low-mass local support structure. An electrical super-module prototype for eight double-sided strip modules has been constructed. The aim is to exercise the multi-module readout chain and to investigate the noise performance of such a system. In this paper, the main components of the current super-module prototype are described and its electrical performance is presented in detail
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