Effect of integration time on the morphometric, densitometric and mechanical properties of the mouse tibia

Micro-Computed Tomography (microCT) images are used to measure morphometric and densitometric properties of bone, and to develop finite element (FE) models to estimate mechanical properties. However, there are concerns about the invasiveness of microCT imaging due to the X-rays ionising radiation induced by the repeated scans on the same animal. Therefore, the best compromise between radiation dose and image quality should be chosen for each preclinical application. In this study, we investigated the effect of integration time (time the bone is exposed to radiation at each rotation step during microCT imaging) on measurements performed on the mouse tibia. Four tibiae were scanned at 10.4 µm voxel size using four different procedures, characterized by decreasing integration time (from 200 ms to 50 ms) and therefore decreasing nominal radiation dose (from 513 mGy to 128 mGy). From each image, trabecular and cortical morphometric parameters, spatial distribution of bone mineral content (BMC) in the whole tibia and FE-based estimations of stiffness and strength were obtained. A high-resolution scan (4.3 µm voxel size) was used to quantify measurement errors. Integration time had the largest effect on trabecular morphometric parameters (7-28%). Lower effects were observed on cortical parameters (1-3%), BMC (1-10%) distribution, and FE-based estimations of mechanical properties (1-3%). In conclusion, the effect of integration time on image-based measurements has been quantified. This data should be considered when defining the in vivo microCT scanning protocols in order to find the best compromise between nominal radiation exposure and accuracy in the estimation of bone parameters

Learning t-doped stabilizer states

In this paper, we present a learning algorithm aimed at learning states obtained from computational basis states by Clifford circuits doped with a finite number t of non-Clifford gates. To tackle this problem, we introduce a novel algebraic framework for t-doped stabilizer states by utilizing tools from stabilizer entropy. Leveraging this new structure, we develop an algorithm that uses sampling from the distribution obtained by squaring expectation values of Pauli operators that can be obtained by Bell sampling on the state and its conjugate in the computational basis. The algorithm requires resources of complexity O(\exp(t)\poly(n)) and exhibits an exponentially small probability of failure.Comment: L.L. and S.O. contributed equally to this wor

Risco cardiometabólico na infância : pode a bilirrubina atuar como mediador associado ao relógio circadiano via disfunção autonómica?

Copyright © Ordem dos Médicos 2020The interesting paper from Yu and colleagues on the association of neonatal serum bilirubin and childhood hypertension recently published in Plos One, flagged up a plausible role of bilirubin as a mediator of hypertension in later life. This is a highly important topic since hypertension, a main cause of cardiometabolic associated morbidity and mortality, may affect 2% to 4% of children. Bilirubin is a toxic endproduct of heme catabolism in the body, commonly seen in newborns and causing jaundice. It is detoxified mainly in the liver by means of several steps involving circadian regulated enzymatic processes. A balanced autonomic output to the liver is crucial for maintenance of the circadian rhythmicity that ensures the normal function of liver metabolic enzymes and glucose level.info:eu-repo/semantics/publishedVersio

Isospectral twirling and quantum chaos

We show that the most important measures of quantum chaos, such as frame potentials, scrambling, Loschmidt echo and out-of-time-order correlators (OTOCs), can be described by the unified framework of the isospectral twirling, namely the Haar average of a k-fold unitary channel. We show that such measures can then always be cast in the form of an expectation value of the isospectral twirling. In literature, quantum chaos is investigated sometimes through the spectrum and some other times through the eigenvectors of the Hamiltonian generating the dynamics. We show that thanks to this technique, we can interpolate smoothly between integrable Hamiltonians and quantum chaotic Hamiltonians. The isospectral twirling of Hamiltonians with eigenvector stabilizer states does not possess chaotic features, unlike those Hamiltonians whose eigenvectors are taken from the Haar measure. As an example, OTOCs obtained with Clifford resources decay to higher values compared with universal resources. By doping Hamiltonians with non-Clifford resources, we show a crossover in the OTOC behavior between a class of integrable models and quantum chaos. Moreover, exploiting random matrix theory, we show that these measures of quantum chaos clearly distinguish the finite time behavior of probes to quantum chaos corresponding to chaotic spectra given by the Gaussian Unitary Ensemble (GUE) from the integrable spectra given by Poisson distribution and the Gaussian Diagonal Ensemble (GDE)

Isospectral twirling and quantum chaos

We show that the most important measures of quantum chaos like frame potentials, scrambling, Loschmidt echo, and out-of-time-order correlators (OTOCs) can be described by the unified framework of the isospectral twirling, namely the Haar average of a $k$-fold unitary channel. We show that such measures can then be always cast in the form of an expectation value of the isospectral twirling. In literature, quantum chaos is investigated sometimes through the spectrum and some other times through the eigenvectors of the Hamiltonian generating the dynamics. We show that, by exploiting random matrix theory, these measures of quantum chaos clearly distinguish the finite time profiles of probes to quantum chaos corresponding to chaotic spectra given by the Gaussian Unitary Ensemble (GUE) from the integrable spectra given by Poisson distribution and the Gaussian Diagonal Ensemble (GDE). On the other hand, we show that the asymptotic values do depend on the eigenvectors of the Hamiltonian. We see that the isospectral twirling of Hamiltonians with eigenvectors stabilizer states does not possess chaotic features, unlike those Hamiltonians whose eigenvectors are taken from the Haar measure. As an example, OTOCs obtained with Clifford resources decay to higher values compared with universal resources. Finally, we show a crossover in the OTOC behavior between a class of integrable models and quantum chaos.Comment: Updated version with several new result

Transitions in entanglement complexity in random quantum circuits by measurements

Random Clifford circuits doped with non Clifford gates exhibit transitions to universal entanglement spectrum statistics [1] and quantum chaotic behavior. In [2] we proved that the injection of Ω(n) non Clifford gates into a n-qubit Clifford circuit drives the transition towards the universal value of the purity fluctuations. In this paper, we show that doping a Clifford circuit with Ω(n) single qubit non Clifford measurements is both necessary and sufficient to drive the transition to universal fluctuations of the purity

Transitions in entanglement complexity in random quantum circuits by measurements

Random Clifford circuits doped with non Clifford gates exhibit transitions to universal entanglement spectrum statistics[1] and quantum chaotic behavior. In [2] we proved that the injection of $O(n)$ non Clifford gates into a $n$-qubit Clifford circuit drives the transition towards the universal value of the purity fluctuations. In this paper, we show that doping a Clifford circuit with $O(n)$ single qubit non Clifford measurements is both necessary and sufficient to drive the transition to universal fluctuations of the purity

Regional nanoindentation properties in different locations on the mouse tibia from C57BL/6 and Balb/C female mice

The local spatial heterogeneity of the material properties of the cortical and trabecular bone extracted from the mouse tibia is not well-known. Nevertheless, its characterization is fundamental to be able to study comprehensively the effect of interventions and to generate computational models to predict the bone strength preclinically. The goal of this study was to evaluate the nanoindentation properties of bone tissue extracted from two different mouse strains across the tibia length and in different sectors. Left tibiae were collected from four female mice, two C57BL/6, and two Balb/C mice. Nanoindentations with maximum 6 mN load were performed on different microstructures, regions along the axis of the tibiae, and sectors (379 in total). Reduced modulus (Er) and hardness (H) were computed for each indentation. Trabecular bone of Balb/C mice was 21% stiffer than that of C57BL/6 mice (20.8 ± 4.1 GPa vs. 16.5 ± 7.1 GPa). Moreover, the proximal regions of the bones were 13–36% less stiff than the mid-shaft and distal regions of the same bones. No significant differences were found for the different sectors for Er and H for Balb/C mice. The bone in the medial sector was found to be 8–14% harder and stiffer than the bone in the anterior or posterior sectors for C57BL/6 mice. In conclusion, this study showed that the nanoindentation properties of the mouse tibia are heterogeneous across the tibia length and the trabecular bone properties are different between Balb/C and C57BL/6 mice. These results will help the research community to identify regions where to characterize the mechanical properties of the bone during preclinical optimisation of treatments for skeletal diseases

RNA framework: An all-in-one toolkit for the analysis of RNA structures and post-transcriptional modifications

RNA is emerging as a key regulator of a plethora of biological processes. While its study has remained elusive for decades, the recent advent of high-throughput sequencing technologies provided the unique opportunity to develop novel techniques for the study of RNA structure and post-transcriptional modifications. Nonetheless, most of the required downstream bioinformatics analyses steps are not easily reproducible, thus making the application of these techniques a prerogative of few laboratories. Here we introduce RNA Framework, an all-in-one toolkit for the analysis of most NGS-based RNA structure probing and post-transcriptional modification mapping experiments. To prove the extreme versatility of RNA Framework, we applied it to both an in-house generated DMS-MaPseq dataset, and to a series of literature available experiments. Notably, when starting from publicly available datasets, our software easily allows replicating authors' findings. Collectively, RNA Framework provides the most complete and versatile toolkit to date for a rapid and streamlined analysis of the RNA epistructurome. RNA Framework is available for download at: http://www.rnaframework.com

Phase transition in Stabilizer Entropy and efficient purity estimation

Stabilizer Entropy (SE) quantifies the spread of a state in the basis of Pauli operators. It is a computationally tractable measure of non-stabilizerness and thus a useful resource for quantum computation. SE can be moved around a quantum system, effectively purifying a subsystem from its complex features. We show that there is a phase transition in the residual subsystem SE as a function of the density of non-Clifford resources. This phase transition has important operational consequences: it marks the onset of a subsystem purity estimation protocol that requires $O(\operatorname{poly}(n)2^t)$ many queries to a circuit containing $t$ non-Clifford gates that prepares the state from a stabilizer state. Thus, for $t=O(\log n)$, it estimates the purity with polynomial resources and, for highly entangled states, attains an exponential speed-up over the known state-of-the-art algorithms