19 research outputs found
Characterization and Verification Environment for the RD53A Pixel Readout Chip in 65 nm CMOS
The RD53 collaboration is currently designing a large scale prototype pixel
readout chip in 65 nm CMOS technology for the phase 2 upgrades at the HL-LHC.
The RD53A chip will be available by the end of the year 2017 and will be
extensively tested to confirm if the circuit and the architecture make a solid
foundation for the final pixel readout chips for the experiments at the HL-LHC.
A test and data acquisition system for the RD53A chip is currently under
development to perform single-chip and multi-chip module measurements. In
addition, the verification of the RD53A design is performed in a dedicated
simulation environment. The concept and the implementation of the test and data
acquisition system and the simulation environment, which are based on a modular
data acquisition and system testing framework, are presented in this work
Probing Quadratic Gravity with the Event Horizon Telescope
Quadratic gravity constitutes a prototypical example of a perturbatively
renormalizable quantum theory of the gravitational interactions. In this work,
we construct the associated phase space of static, spherically symmetric, and
asymptotically flat spacetimes. It is found that the Schwarzschild geometry is
embedded in a rich solution space comprising horizonless, naked singularities
and wormhole solutions. Characteristically, the deformed solutions follow the
Schwarzschild solution up outside of the photon sphere while they differ
substantially close to the center of gravity. We then carry out an analytic
analysis of observable signatures accessible to the Event Horizon Telescope,
comprising the size of the black hole shadow as well as the radiation emitted
by infalling matter. On this basis, we argue that it is the brightness within
the shadow region which constrains the phase space of solutions. Our work
constitutes the first step towards bounding the phase space of black hole type
solutions with a clear quantum gravity interpretation based on observational
data.Comment: 18 pages, 6 figure
Large-Z atoms in the strong-interaction limit of DFT: Implications for gradient expansions and for the Lieb-Oxford bound
We study numerically the strong-interaction limit of the exchange-correlation
functional for neutral atoms and for Bohr atoms as the number of electrons
increases. Using a compact representation, we analyse the second-order gradient
expansion, comparing it with the one for exchange (weak interaction limit). The
two gradient expansions, at strong and weak interaction, turn out to be very
similar in magnitude, but with opposite signs. We find that the point-charge
plus continuum model is surprisingly accurate for the gradient expansion
coefficient at strong coupling, while generalized gradient approximations such
as PBE and PBEsol severely underestimate it. We then use our results to analyse
the Lieb-Oxford bound from the point of view of slowly-varying densities,
clarifying some aspects on the bound at fixed number of electrons.Comment: 11 pages, 5 figure
Neutron irradiation test of depleted CMOS pixel detector prototypes
Charge collection properties of depleted CMOS pixel detector prototypes
produced on p-type substrate of 2 kcm initial resistivity (by LFoundry
150 nm process) were studied using Edge-TCT method before and after neutron
irradiation. The test structures were produced for investigation of CMOS
technology in tracking detectors for experiments at HL-LHC upgrade.
Measurements were made with passive detector structures in which current pulses
induced on charge collecting electrodes could be directly observed. Thickness
of depleted layer was estimated and studied as function of neutron irradiation
fluence. An increase of depletion thickness was observed after first two
irradiation steps to 110 n/cm and 510
n/cm and attributed to initial acceptor removal. At higher fluences the
depletion thickness at given voltage decreases with increasing fluence because
of radiation induced defects contributing to the effective space charge
concentration. The behaviour is consistent with that of high resistivity
silicon used for standard particle detectors. The measured thickness of the
depleted layer after irradiation with 110 n/cm is more than
50 m at 100 V bias. This is sufficient to guarantee satisfactory
signal/noise performance on outer layers of pixel trackers in HL-LHC
experiments
BDAQ53, a versatile pixel detector readout and test system for the ATLAS and CMS HL-LHC upgrades
BDAQ53 is a readout system and verification framework for hybrid pixel
detector readout chips of the RD53 family. These chips are designed for the
upgrade of the inner tracking detectors of the ATLAS and CMS experiments.
BDAQ53 is used in applications where versatility and rapid customization are
required, such as in laboratory testing environments, test beam campaigns, and
permanent setups for quality control measurements. It consists of custom and
commercial hardware, a Python-based software framework, and FPGA firmware.
BDAQ53 is developed as open source software with both software and firmware
being hosted in a public repository.Comment: 6 pages, 6 figure
Large coupling-strength expansion of the M{\o}ller-Plesset adiabatic connection: From paradigmatic cases to variational expressions for the leading terms
We study in detail the first three leading terms of the large
coupling-strength limit of the adiabatic connection that has as
weak-interaction expansion the M{\o}ller-Plesset perturbation theory. We first
focus on the H atom, both in the spin-polarized and the spin-unpolarized case,
reporting numerical and analytical results. In particular, we derive an
asymptotic equation that turns out to have simple analytical solutions for
certain channels. The asymptotic H atom solution for the spin-unpolarized case
is then shown to be variationally optimal for the many-electron spin-restricted
closed-shell case, providing expressions for the large coupling-strength
density functionals up to the third leading order. We also analyze the H2
molecule and the uniform electron gas
Arginase 1 Insufficiency Precipitates Amyloid-\u3cem\u3eβ\u3c/em\u3e Deposition and Hastens Behavioral Impairment in a Mouse Model of Amyloidosis
Alzheimer’s disease (AD) includes several hallmarks comprised of amyloid-β (Aβ) deposition, tau neuropathology, inflammation, and memory impairment. Brain metabolism becomes uncoupled due to aging and other AD risk factors, which ultimately lead to impaired protein clearance and aggregation. Increasing evidence indicates a role of arginine metabolism in AD, where arginases are key enzymes in neurons and glia capable of depleting arginine and producing ornithine and polyamines. However, currently, it remains unknown if the reduction of arginase 1 (Arg1) in myeloid cell impacts amyloidosis. Herein, we produced haploinsufficiency of Arg1 by the hemizygous deletion in myeloid cells using Arg1fl/fl and LysMcreTg/+ mice crossed with APP Tg2576 mice. Our data indicated that Arg1 haploinsufficiency promoted Aβ deposition, exacerbated some behavioral impairment, and decreased components of Ragulator-Rag complex involved in mechanistic target of rapamycin complex 1 (mTORC1) signaling and autophagy. Additionally, Arg1 repression and arginine supplementation both impaired microglial phagocytosis in vitro. These data suggest that proper function of Arg1 and arginine metabolism in myeloid cells remains essential to restrict amyloidosis
Mining Big Data for Tourist Hot Spots: Geographical Patterns of Online Footprints
Understanding the complex, and often unequal, spatiality of tourist
demand in urban contexts requires other methodologies, among which the information base available online and in social networks has gained prominence. Innovation
supported by Information and Communication Technologies in terms of data access
and data exchange has emerged as a complementary supporting tool for the more traditional data collection techniques currently in use, particularly, in urban destinations
where there is the need to more (near)real-time monitoring. The capacity to collect
and analise massive amounts of data on individual and group behaviour is leading to
new data-rich research approaches. This chapter addresses the potential for discovering geographical insights regarding tourists’ spatial patterns within a destination,
based on the analysis of geotagged data available from two social networks.
·info:eu-repo/semantics/publishedVersio
Gradient Expansions for the Large-Coupling Strength Limit of the Møller-Plesset Adiabatic Connection
The adiabatic connection that has, as weak-interaction expansion, the Møller-Plesset perturbation series has been recently shown to have a large coupling-strength expansion, in terms of functionals of the Hartree-Fock density with a clear physical meaning. In this work, we accurately evaluate these density functionals and we extract second-order gradient coefficients from the data for neutral atoms, following ideas similar to the ones used in the literature for exchange, with some modifications. These new gradient expansions will be the key ingredient for performing interpolations that have already been shown to reduce dramatically MP2 errors for large noncovalent complexes. As a byproduct, our investigation of neutral atoms with large number of electrons N indicates that the second-order gradient expansion for exchange grows as N log(N) rather than as N, as often reported in the literature
Gradient Expansions for the Large-Coupling Strength Limit of the Møller-Plesset Adiabatic Connection
[Image: see text] The adiabatic connection that has, as weak-interaction expansion, the Møller–Plesset perturbation series has been recently shown to have a large coupling-strength expansion, in terms of functionals of the Hartree–Fock density with a clear physical meaning. In this work, we accurately evaluate these density functionals and we extract second-order gradient coefficients from the data for neutral atoms, following ideas similar to the ones used in the literature for exchange, with some modifications. These new gradient expansions will be the key ingredient for performing interpolations that have already been shown to reduce dramatically MP2 errors for large noncovalent complexes. As a byproduct, our investigation of neutral atoms with large number of electrons N indicates that the second-order gradient expansion for exchange grows as N log(N) rather than as N, as often reported in the literature