Time Dynamics of the Down-Coupling Phenomenon in 3-D NAND Strings

We present a detailed analysis of the time dynamics of the down-coupling phenomenon (DCP) in 3-D NAND Flash memory strings. The transient time dynamics of the channel potential following the wordline (WL) bias transition fromthe pass voltage to zero is studied via numerical simulation, highlighting the existence of three temporal regimes controlledby different physical processes: electron emission from traps, hole injection from the string edges followed by capture, and propagation along the string. The impact of these processes is separately studied, followed by an analysis of the dependence of the DCP recovery time on architectural parameters. Results highlight the relevant physics and can be used as a design guideline for NAND strings with reduced sensitivity to the DCP

Noise reduction and spatial resolution in CT imaging with the ASIR iterative reconstruction algorithm at different doses and contrasts – a phantom study

Aims and objectives The aim of this study was to quantitatively assess noise reduction and spatial resolution in computed tomography (CT) imaging with the ASIR (Adaptive Statistical Iterative Reconstruction, GE Healthcare) reconstruction algorithm at different kVp, mAs and contrasts. Methods and materials Acquisitions of the Catphan-504 phantom were performed on a PET/CT scanner (Discovery-710, GE Healthcare). CT images were reconstructed using both filtered back projection (FBP) and ASIR with different percentages of reconstruction (20%, 40%, 60%, 80%, 100%). The image noise was estimated for different values of scanning parameters (i.e. tube-load, kilovoltage, pitch, slice thickness). Then, 3D/2D/1D noise power spectrum was estimated. Also, spatial resolution was assessed by obtaining the modulation transfer function (MTF) for a wide range of scanning parameters values and different contrast objects by the circular Edge Spread Function method (using CTP404 modulus) and the Point Spread Function method (using CTP528 modulus). . Results Image noise decreased (up to 50% as compared to FBP) with increasing the percentage of ASIR reconstruction (behaviour more relevant for higher spatial frequencies). Only for low tube load (<56 mAs) and low contrast objects (polistirene with respect to PMMA) acquisitions, MTF analysis showed that ASIR-reconstructed images were characterized by an appreciable reduction in spatial resolution, when compared to FBP-reconstructed images. Conclusion When compared to FBP, ASIR allows a relevant noise reduction without appreciably affecting image quality, except for very low dose and contrast acquisitions

Palladium-catalyzed domino carbopalladation/5-exo-allylic amination of \u3b1-amino allenamides: an efficient entry to enantiopure imidazolidinones

Allenamides of alpha-amino acids were converted into enantiopure 2-vinylimidazolidin-4-ones by a carbopalladation/exo-cyclization process. The products were obtained in 2.5:1-5.5:1 dr, with 94-99% ee. The palladium-catalyzed carbonylative cyclization of the same substrates afforded enone structures. Starting from properly substituted allenamides, an intramolecular carbopalladation followed by intramolecular amination gave rise to tricyclic fused-ring imidazolidinones

Average absorbed breast dose (2ABD): an easy radiation dose index for digital breast tomosynthesis

Background: To propose a practical and simple method to individually evaluate the average absorbed dose for digital breast tomosynthesis. Methods: The method is based on the estimate of incident air kerma (ka,i) on the breast surface. An analytical model was developed to calculate the ka,i from the tube voltage, tube load, breast thickness, x-ray tube yield, and anode-filter combination. A homogeneous phantom was employed to simulate the breast in experimental measurements and to assess the dose-depth relationship. The ka,i values were employed to calculate the “average absorbed breast dose” (2ABD) index. Four mammographic units were used to develop and test our method under many conditions close to clinical settings. The average glandular dose (AGD) calculated following the method described by Dance et al., and the 2ABD computed through our method (i.e., from the exposure parameters) were compared in a number of conditions. Results: A good agreement was obtained between the ka,i computed through our model and that measured under different clinical conditions: discrepancies &lt; 6% were found in all conditions. 2ABD matches with a good accuracy the AGD for a 100% glandular-breast: the minimum, maximum, and mean differences were &lt; 0.1%, 7%, and 2.4%, respectively; the discrepancies increase with decreasing breast glandularity. Conclusions: The proposed model, based on only few exposure parameters, represents a simple way to individually calculate an index, 2ABD, which can be interpreted as the average absorbed dose in a homogeneous phantom, approximating a 100% glandular breast. The method could be easily implemented in any mammographic device performing DBT

Classification and stability of simple homoclinic cycles in R^5

The paper presents a complete study of simple homoclinic cycles in R^5. We find all symmetry groups Gamma such that a Gamma-equivariant dynamical system in R^5 can possess a simple homoclinic cycle. We introduce a classification of simple homoclinic cycles in R^n based on the action of the system symmetry group. For systems in R^5, we list all classes of simple homoclinic cycles. For each class, we derive necessary and sufficient conditions for asymptotic stability and fragmentary asymptotic stability in terms of eigenvalues of linearisation near the steady state involved in the cycle. For any action of the groups Gamma which can give rise to a simple homoclinic cycle, we list classes to which the respective homoclinic cycles belong, thus determining conditions for asymptotic stability of these cycles.Comment: 34 pp., 4 tables, 30 references. Submitted to Nonlinearit

Evaluation of Dosimetric Properties in Full Field Digital Mammography (FFDM) - Development of a New Dose Index

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Reduced ventricular proliferation in the foetal cortex following maternal inflammation in the mouse

It has been well established that maternal inflammation during pregnancy alters neurological function in the offspring, but its impact on cortical development and long-term consequences on the cytoarchitecture is largely unstudied. Here we report that lipopolysaccharide-induced systemic maternal inflammation in C57Bl/6 mice at embryonic Day 13.5 of pregnancy, as early as 8 h after challenge, caused a significant reduction in cell proliferation in the ventricular zone of the developing cerebral cortex, as revealed by quantification of anti-phospho-Histone H3 immunoreactivity and bromodeoxyuridine pulse labelling. The angle of mitotic cleavage, determined from analysis of haematoxylin and eosin staining, cyclin E1 gene expression and the pattern of β-catenin immunoreactivity were also altered by the challenge, which suggests a change from symmetric to asymmetric division in the radial progenitor cells. Modifications of cortical lamination and gene expression patterns were detected at post-natal Day 8 suggesting prolonged consequences of these alterations during embryonic development. Cellular uptake of proteins from the cerebrospinal fluid was observed in brains from lipopolysaccharide-treated animals in radial progenitor cells. However, the foetal blood–brain barrier to plasma proteins remained intact. Together, these results indicate that maternal inflammation can disrupt the ventricular surface and lead to decreased cellular proliferation. Changes in cell density in Layers IV and V at post-natal Day 8 show that these initial changes have prolonged effects on cortical organization. The possible shift in the fate of progeny and the resulting alterations in the relative cell numbers in the cerebral cortex following a maternal inflammatory response shown here will require further investigation to determine the long-term consequences of inflammation on the development of neuronal circuitry and behaviour

Measurement of the cross-section and charge asymmetry of WW bosons produced in proton-proton collisions at s=8\sqrt{s}=8 TeV with the ATLAS detector

This paper presents measurements of the $W^+ \rightarrow \mu^+\nu$ and $W^- \rightarrow \mu^-\nu$ cross-sections and the associated charge asymmetry as a function of the absolute pseudorapidity of the decay muon. The data were collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with the ATLAS experiment at the LHC and correspond to a total integrated luminosity of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the 1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured with an uncertainty between 0.002 and 0.003. The results are compared with predictions based on next-to-next-to-leading-order calculations with various parton distribution functions and have the sensitivity to discriminate between them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13

Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in √s=13 TeV pp collisions with the ATLAS detector

A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of √s=13  TeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139  fb−1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015–2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV

Search for direct stau production in events with two hadronic tau-leptons in root s=13 TeV pp collisions with the ATLAS detector

A search for the direct production of the supersymmetric partners ofτ-leptons (staus) in final stateswith two hadronically decayingτ-leptons is presented. The analysis uses a dataset of pp collisions corresponding to an integrated luminosity of139fb−1, recorded with the ATLAS detector at the LargeHadron Collider at a center-of-mass energy of 13 TeV. No significant deviation from the expected StandardModel background is observed. Limits are derived in scenarios of direct production of stau pairs with eachstau decaying into the stable lightest neutralino and oneτ-lepton in simplified models where the two staumass eigenstates are degenerate. Stau masses from 120 GeV to 390 GeV are excluded at 95% confidencelevel for a massless lightest neutralino