171 research outputs found
Iginio Tansini revisited
The origin of the muscolocutaneous latissimus dorsi flap dates back to 1906 when Igino Tansini, an Italian surgeon, described a procedure to reconstruct the mastectomy defect. After a detailed study of Tansini's original description and drawings, new insights about the pedicle of its compound flap have been found, showing that it has the same pedicle of the scapular flap. In the end, Tansini's flap should be more correctly considered as a compound musculocutaneous scapular flap
Progressive collapse fragility of European reinforced concrete buildings
Structural safety is generally assessed without consideration of abnormal load conditions that may give rise to global system collapse after local failure in one or a few components. Particularly in the case of high-risk structures, Eurocode 1 recommends a systematic risk assessment of the structure, considering either identified threats or unspecified damaging events. Nonetheless, a comprehensive probabilistic assessment of European structures is strongly needed. In such a context, this paper presents the outcomes of fragility analyses performed on reinforced concrete framed buildings, proposing a set of fragility models that can be used for probabilistic assessment and management of the risk of progressive collapse. Gravity-load designed and earthquake-resistant building structures were considered and respectively designed in accordance with Eurocodes 2 and 8. Fiber-based finite element models were developed and analyzed under sudden removal of one or more columns, allowing structural performance and damage propagation to be evaluated. Based upon statistics and probability distribution functions for material properties, geometry, and design loads of the building class under study, a Monte Carlo simulation was performed to generate both 2D and 3D models. Structural performance was assessed by incremental-mass nonlinear dynamic analysis, capturing the attainment of limit states either at sectional or global levels. Probability distribution functions were then fitted to fragility points in order to provide fragility functions at multiple damage states for their use in progressive collapse risk assessment. The analysis results show the significant impact of seismic design rules and secondary beams on progressive collapse fragility
Integration of amorphous silicon balanced photodiodes and thin film heaters for biosensing application
This work presents the development and testing of an integrated system for on-chip detection of thermochemiluminescent biomolecules. The activation energy of the reaction is provided by a transparent structure of thin film heaters deposited on one side of a glass substrate. Light, passing through the substrate, reaches an array of amorphous silicon differential structure deposited on the opposite side of the glass substrate. The structure is designed to perform differential current measurements between a light- shielded diode, whose current is sensitive only to temperature, and a photosensor, sensitive to both incident light and temperature. The device therefore balances the thermal variations of the photodiode current and reduces the dark-current noise. These features make the presented system very appealing as highly miniaturized micro-analytical devices for biosensing applications
Assessing the Performance of OpenTitan as Cryptographic Accelerator in Secure Open-Hardware System-on-Chips
RISC-V open-source systems are emerging in deployment scenarios where safety
and security are critical. OpenTitan is an open-source silicon root-of-trust
designed to be deployed in a wide range of systems, from high-end to deeply
embedded secure environments. Despite the availability of various cryptographic
hardware accelerators that make OpenTitan suitable for offloading cryptographic
workloads from the main processor, there has been no accurate and quantitative
establishment of the benefits derived from using OpenTitan as a secure
accelerator. This paper addresses this gap by thoroughly analysing strengths
and inefficiencies when offloading cryptographic workloads to OpenTitan. The
focus is on three key IPs - HMAC, AES, and OpenTitan Big Number accelerator
(OTBN) - which can accelerate four security workloads: Secure Hash Functions,
Message Authentication Codes, Symmetric cryptography, and Asymmetric
cryptography. For every workload, we develop a bare-metal driver for the
OpenTitan accelerator and analyze its efficiency when computation is offloaded
from a RISC-V application core within a System-on-Chip designed for secure
Cyber-Physical Systems applications. Finally, we assess it against a software
implementation on the application core. The characterization was conducted on a
cycle-accurate RTL simulator of the System-on-Chip (SoC). Our study
demonstrates that OpenTitan significantly outperforms software implementations,
with speedups ranging from 4.3x to 12.5x. However, there is potential for even
greater gains as the current OpenTitan utilizes a fraction of the accelerator
bandwidths, which ranges from 16% to 61%, depending on the memory being
accessed and the accelerator used. Our results open the way to the optimization
of OpenTitan-based secure platforms, providing design guidelines to unlock the
full potential of its accelerators in secure applications.Comment: 8 pages, 2 figures, accepted at CF'24 conference, pre camera-ready
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Single-cell DNA Sequencing Data: a Pipeline for Multi-Sample Analysis
In order to help cancer researchers in understanding tumor heterogeneity and its evolutionary dynamics, we propose a software pipeline to explore intra-tumor heterogeneity by means of scDNA sequencing data
Thalamo-cortical network activity between migraine attacks. Insights from MRI-based microstructural and functional resting-state network correlation analysis
BACKGROUND:
Resting state magnetic resonance imaging allows studying functionally interconnected brain networks. Here we were aimed to verify functional connectivity between brain networks at rest and its relationship with thalamic microstructure in migraine without aura (MO) patients between attacks.
METHODS:
Eighteen patients with untreated MO underwent 3 T MRI scans and were compared to a group of 19 healthy volunteers (HV). We used MRI to collect resting state data among two selected resting state networks, identified using group independent component (IC) analysis. Fractional anisotropy (FA) and mean diffusivity (MD) values of bilateral thalami were retrieved from a previous diffusion tensor imaging study on the same subjects and correlated with resting state ICs Z-scores.
RESULTS:
In comparison to HV, in MO we found significant reduced functional connectivity between the default mode network and the visuo-spatial system. Both HV and migraine patients selected ICs Z-scores correlated negatively with FA values of the thalamus bilaterally.
CONCLUSIONS:
The present results are the first evidence supporting the hypothesis that an abnormal resting within networks connectivity associated with significant differences in baseline thalamic microstructure could contribute to interictal migraine pathophysiology
TitanCFI: Toward Enforcing Control-Flow Integrity in the Root-of-Trust
Modern RISC-V platforms control and monitor security-critical systems such as
industrial controllers and autonomous vehicles. While these platforms feature a
Root-of-Trust (RoT) to store authentication secrets and enable secure boot
technologies, they often lack Control-Flow Integrity (CFI) enforcement and are
vulnerable to cyber-attacks which divert the control flow of an application to
trigger malicious behaviours. Recent techniques to enforce CFI in RISC-V
systems include ISA modifications or custom hardware IPs, all requiring ad-hoc
binary toolchains or design of CFI primitives in hardware. This paper proposes
TitanCFI, a novel approach to enforce CFI in the RoT. TitanCFI modifies the
commit stage of the protected core to stream control flow instructions to the
RoT and it integrates the CFI enforcement policy in the RoT firmware. Our
approach enables maximum reuse of the hardware resource present in the
System-on-Chip (SoC), and it avoids the design of custom IPs and the
modification of the compilation toolchain, while exploiting the RoT
tamper-proof storage and cryptographic accelerators to secure CFI metadata. We
implemented the proposed architecture on a modern RISC-V SoC along with a
return address protection policy in the RoT, and benchmarked area and runtime
overhead. Experimental results show that TitanCFI achieves overhead comparable
to SoA hardware CFI solutions for most benchmarks, with lower area overhead,
resulting in 1% of additional area occupation.Comment: 6 pages, 1 figure, accepted at DATE'24 conference, pre camera-ready
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Cerebral gray matter volume in patients with chronic migraine: correlations with clinical features
Abstract
Background
To date, few MRI studies have been performed in patients affected by chronic migraine (CM), especially in those without medication overuse. Here, we performed magnetic resonance imaging (MRI) voxel-based morphometry (VBM) analyses to investigate the gray matter (GM) volume of the whole brain in patients affected by CM. Our aim was to investigate whether fluctuations in the GM volumes were related to the clinical features of CM.
Methods
Twenty untreated patients with CM without a past medical history of medication overuse underwent 3-Tesla MRI scans and were compared to a group of 20 healthy controls (HCs). We used SPM12 and the CAT12 toolbox to process the MRI data and to perform VBM analyses of the structural T1-weighted MRI scans. The GM volume of patients was compared to that of HCs with various corrected and uncorrected thresholds. To check for possible correlations, patients’ clinical features and GM maps were regressed.
Results
Initially, we did not find significant differences in the GM volume between patients with CM and HCs (p < 0.05 corrected for multiple comparisons). However, using more-liberal uncorrected statistical thresholds, we noted that compared to HCs, patients with CM exhibited clusters of regions with lower GM volumes including the cerebellum, left middle temporal gyrus, left temporal pole/amygdala/hippocampus/pallidum/orbitofrontal cortex, and left occipital areas (Brodmann areas 17/18). The GM volume of the cerebellar hemispheres was negatively correlated with the disease duration and positively correlated with the number of tablets taken per month.
Conclusion
No gross morphometric changes were observed in patients with CM when compared with HCs. However, using more-liberal uncorrected statistical thresholds, we observed that CM is associated with subtle GM volume changes in several brain areas known to be involved in nociception/antinociception, multisensory integration, and analgesic dependence. We speculate that these slight morphometric impairments could lead, at least in a subgroup of patients, to the development and continuation of maladaptive acute medication usage
Interpolating the Sherrington-Kirkpatrick replica trick
The interpolation techniques have become, in the past decades, a powerful
approach to lighten several properties of spin glasses within a simple
mathematical framework. Intrinsically, for their construction, these schemes
were naturally implemented into the cavity field technique, or its variants as
the stochastic stability or the random overlap structures. However the first
and most famous approach to mean field statistical mechanics with quenched
disorder is the replica trick. Among the models where these methods have been
used (namely, dealing with frustration and complexity), probably the best known
is the Sherrington-Kirkpatrick spin glass: In this paper we are pleased to
apply the interpolation scheme to the replica trick framework and test it
directly to the cited paradigmatic model: interestingly this allows to obtain
easily the replica-symmetric control and, synergically with the broken replica
bounds, a description of the full RSB scenario, both coupled with several minor
theorems. Furthermore, by treating the amount of replicas as an
interpolating parameter (far from its original interpretation) this can be
though of as a quenching temperature close to the one introduce in
off-equilibrium approaches and, within this viewpoint, the proof of the
attended commutativity of the zero replica and the infinite volume limits can
be obtained.Comment: This article is dedicated to David Sherrington on the occasion of his
seventieth birthda
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