192 research outputs found
Wave: A New Family of Trapdoor One-Way Preimage Sampleable Functions Based on Codes
We present here a new family of trapdoor one-way Preimage Sampleable
Functions (PSF) based on codes, the Wave-PSF family. The trapdoor function is
one-way under two computational assumptions: the hardness of generic decoding
for high weights and the indistinguishability of generalized -codes.
Our proof follows the GPV strategy [GPV08]. By including rejection sampling, we
ensure the proper distribution for the trapdoor inverse output. The domain
sampling property of our family is ensured by using and proving a variant of
the left-over hash lemma. We instantiate the new Wave-PSF family with ternary
generalized -codes to design a "hash-and-sign" signature scheme which
achieves existential unforgeability under adaptive chosen message attacks
(EUF-CMA) in the random oracle model. For 128 bits of classical security,
signature sizes are in the order of 15 thousand bits, the public key size in
the order of 4 megabytes, and the rejection rate is limited to one rejection
every 10 to 12 signatures.Comment: arXiv admin note: text overlap with arXiv:1706.0806
Coupling FEM, Bloch Waves and TMM in Meta Poroelastic Laminates
The propagation of airborne plane waves in the pres-
ence of a meta poroelastic laminate, that is a poroelas-
tic matrix coated with thin elastic layers at its facings
5 and periodically-embedded with inclusions, is studied.
Using the Finite Element Method (FEM) only would
result in a drastic increase of the degrees of freedom
due to the fine mesh required to account for the very
thin coatings. Here, the approach relies on: the Bloch
10 wave expansion of the fields in air; the modal Trans-
fer Matrix Method to account for the coatings; and
the coupling with the FEM model of the poroelas-
tic matrix and the resonant inclusions. The model
is developed for reflection and transmission problems
15 and it can account for coatings with multiple layers.
The procedure induces the addition of the Bloch co-
efficients in the FEM’s linear system at a negligible
additional computational cost. It is applied to the
meta poroelastic laminates with poroelastic inclusions
20 and rubber shell inclusions. The results are compared
with those from the Multiple Scattering Theory and
an excellent agreement between the methods is found.
The approach offers a numerically-efficient way to ac-
count for coatings applied to meta poroelastic layers,
25 and finds applications in industrial prototypes where
coatings are widely used
Innovative Virtual Lab for Improving Safety and Port Operations
Computer simulation makes it possible to reproduce real systems and processes in a synthetic environment. In this way virtual analysis turn to be possible and it complex scenarios are suitable to be simulated. In the proposed paper is presented a port system where to study the behavior respect operations and accidents and to consider interaction among multiple players. The simulation is applied to create a Virtual Lab able to evaluate and investigate the development of new procedures, contingency plans during crises. The development of models to be used in simulations is clearly a critical aspect, since the consistency of the simulation depend on the quality of the models and their interaction; in this case the authors used their experience in the field to guarantee a successful Verification and Validation. In this case study, models are used for simulations of phenomena related to port accidents and crises with particular attention to dispersion system of liquid contaminant on sea surface and dispersion of toxic gases into atmosphere. These models have been tested in the Alacres2 simulator in order to create as an effective tool to observe and study the evolution and impact of dangerous situations, as well as a decision-making support to define response plans crises
The effect of bariatric surgery type on cardiac reverse remodelling
Introduction: Bariatric surgery is effective in reversing adverse cardiac remodelling in obesity. However, it is unclear whether the three commonly performed operations; Roux-en-Y Gastric Bypass (RYGB), Laparoscopic Sleeve Gastrectomy (LSG) and Laparoscopic Adjustable Gastric Band (LAGB) are equal in their ability to reverse remodelling. Methods: Fifty-eight patients underwent CMR to assess left ventricular mass (LVM), LV mass:volume ratio (LVMVR) and LV eccentricity index (LVei) before and after bariatric surgery (26 RYGB, 22 LSG and 10 LAGB), including 46 with short-term (median 251–273 days) and 43 with longer-term (median 983–1027 days) follow-up. Abdominal visceral adipose tissue (VAT) and epicardial adipose tissue (EAT) were also assessed. Results: All three procedures resulted in significant decreases in excess body weight (48–70%). Percentage change in VAT and EAT was significantly greater following RYGB and LSG compared to LAGB at both timepoints (VAT:RYGB −47% and −57%, LSG −47% and −54%, LAGB −31% and −25%; EAT:RYGB −13% and −14%, LSG –16% and −19%, LAGB −5% and −5%). Patients undergoing LAGB, whilst having reduced LVM (−1% and −4%), had a smaller decrease at both short (RYGB: −8%, p < 0.005; LSG: −11%, p < 0.0001) and long (RYGB: −12%, p = 0.009; LSG: −13%, p < 0.0001) term timepoints. There was a significant decrease in LVMVR at the long-term timepoint following both RYGB (−7%, p = 0.006) and LSG (−7%, p = 0.021), but not LAGB (−2%, p = 0.912). LVei appeared to decrease at the long-term timepoint in those undergoing RYGB (−3%, p = 0.063) and LSG (−4%, p = 0.015), but not in those undergoing LAGB (1%, p = 0.857). In all patients, the change in LVM correlated with change in VAT (r = 0.338, p = 0.0134), while the change in LVei correlated with change in EAT (r = 0.437, p = 0.001). Conclusions: RYGB and LSG appear to result in greater decreases in visceral adiposity, and greater reverse LV remodelling with larger reductions in LVM, concentric remodelling and pericardial restraint than LAGB
Remodelling of human atrial K+ currents but not ion channel expression by chronic β-blockade
Chronic β-adrenoceptor antagonist (β-blocker) treatment in patients is associated with a potentially anti-arrhythmic prolongation of the atrial action potential duration (APD), which may involve remodelling of repolarising K+ currents. The aim of this study was to investigate the effects of chronic β-blockade on transient outward, sustained and inward rectifier K+ currents (ITO, IKSUS and IK1) in human atrial myocytes and on the expression of underlying ion channel subunits. Ion currents were recorded from human right atrial isolated myocytes using the whole-cell-patch clamp technique. Tissue mRNA and protein levels were measured using real time RT-PCR and Western blotting. Chronic β-blockade was associated with a 41% reduction in ITO density: 9.3 ± 0.8 (30 myocytes, 15 patients) vs 15.7 ± 1.1 pA/pF (32, 14), p < 0.05; without affecting its voltage-, time- or rate dependence. IK1 was reduced by 34% at −120 mV (p < 0.05). Neither IKSUS, nor its increase by acute β-stimulation with isoprenaline, was affected by chronic β-blockade. Mathematical modelling suggested that the combination of ITO- and IK1-decrease could result in a 28% increase in APD90. Chronic β-blockade did not alter mRNA or protein expression of the ITO pore-forming subunit, Kv4.3, or mRNA expression of the accessory subunits KChIP2, KChAP, Kvβ1, Kvβ2 or frequenin. There was no reduction in mRNA expression of Kir2.1 or TWIK to account for the reduction in IK1. A reduction in atrial ITO and IK1 associated with chronic β-blocker treatment in patients may contribute to the associated action potential prolongation, and this cannot be explained by a reduction in expression of associated ion channel subunits
An IND-CCA-Secure Code-Based EncryptionScheme Using Rank Metric
The use of rank instead of Hamming metric has been proposed to address the main drawback of code-based cryptography: large key sizes. There exist several Key Encapsulation Mechanisms (KEM) and Public Key Encryption (PKE) schemes using rank metric including some submissions to the NIST call for standardization of Post-Quantum Cryptography. In this work, we present an IND-CCA PKE scheme based on the McEliece adaptation to rank metric proposed by Loidreau at PQC 2017. This IND-CCA PKE scheme based on rank metric does not use a hybrid construction KEM + symmetric encryption. Instead, we take advantage of the bigger message space obtained by the different parameters chosen in rank metric, being able to exchange multiple keys in one ciphertext. Our proposal is designed considering some specific properties of the random error generated during the encryption. We prove our proposal IND-CCA-secure in the QROM by using a security notion called disjoint simulatability introduced by Saito et al. in Eurocrypt 2018. Moreover, we provide security bounds by using the semi-oracles introduced by Ambainis et al
Sources and Sinks of Greenhouse Gases from European Grasslands and Mitigation Options: The ‘GreenGrass’ Project
Adapting the management of grasslands may be used to enhance carbon sequestration into soil, but could also increase N2O and CH4 emissions. In support of the European post-Kyoto policy, the European \u27GreenGrass\u27 project (EC FP5, EVK2-CT2001-00105) has three main objectives: i) to reduce the large uncertainties concerning the estimates of CO2, N2O and CH4 fluxes to and from grassland plots under different climatic conditions and assess their global warming potential, ii) to measure net greenhouse gas (GHG) fluxes for different management which reflect potential mitigation options, iii) to construct a model of the controlling processes to quantify the net fluxes and to evaluate mitigation scenarios by up-scaling to a European level
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