866 research outputs found
Omental well-differentiated liposarcoma: US, CT and MR findings
Liposarcomas are the most common of sarcoma tumours, they are usually located in the lower limbs, retroperitoneum,
or abdominal cavity; up to date, only a few cases of omental liposarcoma with different histotype have been described. We present a case of omental well-differentiated liposarcoma and discuss imaging findings on ultrasound, computed tomography, and magnetic resonance to differentiate omental liposarcomas from other abdominal tumour entities
Coherent 100G Nonlinear Compensation with Single-Step Digital Backpropagation
Enhanced-SSFM digital backpropagation (DBP) is experimentally demonstrated
and compared to conventional DBP. A 112 Gb/s PM-QPSK signal is transmitted over
a 3200 km dispersion-unmanaged link. The intradyne coherent receiver includes
single-step digital backpropagation based on the enhanced-SSFM algorithm. In
comparison, conventional DBP requires twenty steps to achieve the same
performance. An analysis of the computational complexity and structure of the
two algorithms reveals that the overall complexity and power consumption of DBP
are reduced by a factor of 16 with respect to a conventional implementation,
while the computation time is reduced by a factor of 20. As a result, the
proposed algorithm enables a practical and effective implementation of DBP in
real-time optical receivers, with only a moderate increase of the computational
complexity, power consumption, and latency with respect to a simple
feed-forward equalizer for dispersion compensation.Comment: This work has been presented at Optical Networks Design & Modeling
(ONDM) 2015, Pisa, Italy, May 11-14, 201
Relaxation of a steep density gradient in a simple fluid: comparison between atomistic and continuum modeling
We compare dynamical nonequilibrium molecular dynamics and continuum
simulations of the dynamics of relaxation of a fluid system characterized by a
non uniform density profile. Results match quite well as long as the
lengthscale of density nonuniformities are greater than the molecular scale (10
times the molecular size). In presence of molecular scale features some of the
continuum fields (e.g. density and momentum) are in good agreement with
atomistic counterparts, but are smoother. On the contrary, other fields, such
at the temperature field, present very large difference with respect to
reference (atomistic) ones. This is due to the limited accuracy of some of the
empirical relations used in continuum models, the equation of state of the
fluid in the example considered
Optical Time-Frequency Packing: Principles, Design, Implementation, and Experimental Demonstration
Time-frequency packing (TFP) transmission provides the highest achievable
spectral efficiency with a constrained symbol alphabet and detector complexity.
In this work, the application of the TFP technique to fiber-optic systems is
investigated and experimentally demonstrated. The main theoretical aspects,
design guidelines, and implementation issues are discussed, focusing on those
aspects which are peculiar to TFP systems. In particular, adaptive compensation
of propagation impairments, matched filtering, and maximum a posteriori
probability detection are obtained by a combination of a butterfly equalizer
and four 8-state parallel Bahl-Cocke-Jelinek-Raviv (BCJR) detectors. A novel
algorithm that ensures adaptive equalization, channel estimation, and a proper
distribution of tasks between the equalizer and BCJR detectors is proposed. A
set of irregular low-density parity-check codes with different rates is
designed to operate at low error rates and approach the spectral efficiency
limit achievable by TFP at different signal-to-noise ratios. An experimental
demonstration of the designed system is finally provided with five
dual-polarization QPSK-modulated optical carriers, densely packed in a 100 GHz
bandwidth, employing a recirculating loop to test the performance of the system
at different transmission distances.Comment: This paper has been accepted for publication in the IEEE/OSA Journal
of Lightwave Technolog
Volatile organic compounds (VOCs) from diffuse degassing areas: Interstitial soil gases as message bearers from deep hydrothermal reservoirs
Programmable transponder, code and differentiated filter configuration in elastic optical networks
Under–expanded jet noise prediction using surrogate models based on artificial neural networks
Is contrast-enhanced US alternative to spiral CT in the assessment of treatment outcome of radiofrequency ablation in hepatocellular carcinoma?
Purpose: The present study was conducted to assess the efficacy of contrast-enhanced ultrasound with low mechanical index in evaluating the response of percutaneous radiofrequency ablation treatment of hepatocellular carcinoma by comparing it with 4-row spiral computed tomography. Materials and Methods: 100 consecutive patients (65 men and 35 women; age range: 62 – 76 years) with solitary hepatocellular carcinomas (mean lesion diameter: 3.7cm± 1.1cm SD) underwent internally cooled radiofrequency ablation. Therapeutic response was evaluated at one month after the treatment with triple-phasic contrast-enhanced spiral CT and low-mechanical index contrast-enhanced ultrasound following bolus injection of 2.4 ml of Sonovue (Bracco, Milan). 60 out of 100 patients were followed up for another 3 months. Contrast-enhanced sonographic studies were reviewed by two blinded radiologists in consensus. Sensitivity, specificity, NPV and PPV of contrast-enhanced ultrasound examination were determined. Results: After treatment, contrast-enhanced ultrasound identified persistent signal enhancement in 24 patients (24%), whereas no intratumoral enhancement was detected in the remaining 76 patients (76%). Using CT imaging as gold standard, the sensitivity, specificity, NPV, and PPV of contrast enhanced ultrasound were 92.3% (95% CI = 75.9 – 97.9%), 100% (95% CI = 95.2 – 100%), 97.4% (95% CI = 91.1 – 99.3%), and 100% (95% CI = 86.2 – 100%). Conclusion: Contrast-enhanced ultrasound with low mechanical index using Sonovue is a feasible tool in evaluating the response of hepatocellular carcinoma to radiofrequency ablation. Accuracy is comparable to 4-row spiral CT
- …