End-to-end Deep Learning for VCSEL’s Nonlinear Digital Pre-Distortion

We propose a novel optimization method for a Neural Network based Digital Pre-Distorter (DPD), applied in Intensity Modulation-Direct Detection transmission systems leveraging Multi-Modal Fiber and Vertical-Cavity Surface-Emitting Laser. We train the DPD using End-to-end Deep Learning of the optical link, together with a Direct Learning Approach leveraging experimental measurements for modeling the transmission channel. The optimization considers VCSEL amplitude constraints, the use of an FFE at the receiver side, and the presence of a receiver non-flat Colored Gaussian Noise (CGN). We verify our optimized DPD on an experimental setup transmitting a 92 Gbps PAM-4 modulated signal. We achieve, for BER=0.01, a performance gain of more than 1 dB in terms of Optical Path Loss with respect to the best performing non-pre-distorted scenario

Experimental VCSEL Digital Twin modeling for net 100 Gb/s/λ nonlinear Digital Pre-Distortion

We experimentally model a VCSEL-based optical transmitter for high speed intra data center interconnects using a convolutional neural network digital twin. The device is able to effectively reproduce the VCSEL linear and nonlinear distortions on PAM4 signals transmitted at 107.2 Gbps, thus enabling the optimization of nonlinear VCSEL-MMF digital pre-distorters

Nonlinear Pre-distortion through a Multi-rate End-to-end Learning Approach over VCSEL-MMF IM-DD Optical Links

We experimentally demonstrate a nonlinear digital pre-distorter for PAM-M shaping in VCSEL+MMF IM-DD links able to operate at a generic baud rate using a fractional sample-per-symbol Neural Network. We focus on efficient and practical multi-rate operation, signal amplitude constraints, and linear equalizer at the receiver

A Multi-Rate Approach for Nonlinear Pre-Distortion Using End-to-End Deep Learning in IM-DD Systems

Modern intra-data center (IDC) interconnects leverage robust and low-cost intensity modulation (IM) and direct detection (DD) optical links, based on multimode fibers (MMFs) and vertical-cavity surface-emitting lasers (VCSELs). Current solutions, based on on-off keying (OOK) modulations, reach up to 25-50 Gbps per lane over nearly 100 meters. The actual target for IDCs is to increase VCSEL-MMF links capacity up to 100 Gbps, using PAM-4 on the same devices. To counteract the consequent linear and nonlinear distortions affecting the transmitted signals, an effective solution is to exploit digital signal processing (DSP). In this manuscript, we propose a novel method to optimize a nonlinear artificial neural network (ANN) digital pre-distorter (DPD), based on End-to-end (E2E) learning, that, trained jointly with a Feed-Forward Equalizer (FFE), fulfills physical amplitude constraints and handles different ratio between the sampling rates incurring along with an optical IM-DD system. We indeed propose an E2E ANN system operating simultaneously at different sampling frequencies. We moreover propose in our training method a substitution to the time-domain injection of the receiver noise in the system with an additive regularization term in the FFE gradient loss. We experimentally show the advantages of our proposed DPD comparing the bit error rate (BER) performance against the same scenario without DPD. We assess the gain in terms of Gross Bit Rate and Optical Path Loss (OPL), at given BER targets, for different fiber lengths

Through-and-through femorofemoral wire retrograde technique for the E-nside precannulated inner branch thoracoabdominal stent graft

The E-nside multibranched stent graft (Jotec GmbH, Hechingen, Germany) is the first and only off-the-shelf thoracoabdominal prosthesis with precannulated inner branches. Usually, after the device deployment, target vessel stenting will be facilitated by antegrade inner branch cannulation to retrieve the precannulated guide. In the literature, the use of antegrade access has been associated with the potential risk of cerebral and systemic embolization. Therefore, other retrograde techniques have been described. We have reported a new retrograde approach using a precannulated through-and-through femorofemoral wire technique for target vessel catheterization

Fifty Hertz electromagnetic field exposure stimulates secretion of β-amyloid peptide in cultured human neuroglioma

Recent epidemiological studies raise the possibility that individuals with occupational exposure to low frequency (50-60 Hz) electromagnetic fields (LF-EMF), are at increased risk of Alzheimer's disease (AD). However, the mechanisms through which LF-EMF may affect AD pathology are unknown. We here tested the hypothesis that the exposure to LF-EMF may affect amyloidogenic processes. We examined the effect of exposure to 3.1 mT 50 Hz LF-EMF on Abeta secretion in H4 neuroglioma cells stably overexpressing human mutant amyloid precursor protein. We found that overnight exposure to LF-EMF induces a significant increase of amyloid-beta peptide (Abeta) secretion, including the isoform Abeta 1-42, without affecting cell survival. These findings show for the first time that exposure to LF-EMF stimulates Abeta secretion in vitro, thus alluding to a potential link between LF-EMF exposure and APP processing in the brain

Open conversion following Nellix Endovascular Aneurysm Sealing (EVAS)

The Nellix Endovascular Aneurysm Sealing (EVAS) System (Endologix, Irvine, California, USA) was presented as a novel concept in the treatment of abdominal aortic aneurysm (AAA). After numerous adverse events, the device has been voluntarily withdrawn from the market by the manufacturer. The purpose of this video is to describe the technical approach of a successful explantation of the Nellix endograft in a patient who underwent EVAS for AAA. The patient\u2019s consent for publication was obtained

Long-term follow-up of adventitial cyst surgical excision in external iliac vein

Adventitial cystic disease of the venous system is an extremely rare condition. Forty-five cases have been described in the literature during the last 70 years, but they may not be representative of the real incidence of this pathologic process. We report a case of an adventitial cyst compressing the right external iliac vein and presenting with edema of the ipsilateral leg. Ultrasound imaging and computed tomography angiography showed the typical features of cystic disease and venous stenosis. Cyst excision was performed with a double surgical access. No perioperative complications were reported. There was no recurrence at 4-year follow-up

Extensive congenital asymptomatic renal arteriovenous malformation

Renal arteriovenous malformations (AVM) are abnormal communications between the intrarenal arterial and venous systems. These lesions may present with a wide range of signs and symptoms, including hypertension and hematuria. We report a case of a 71-year-old woman with incidentally diagnosis of asymptomatic right renal AVM

Treg/Tcon Immunotherapy and High Dose Marrow Irradiation Ensure Full Control of Leukemia Relapse in Haploidentical Transplantation

Allogeneic hematopoietic stem cell transplantation (HSCT) is the most powerful therapy for patients with high risk of relapse. In spite of that, no matter the donor source or conditioning regimen used, leukemia relapse is still the leading cause of HSCT failure. In HLA-haploidentical HSCT, we recently applied a clinical protocol consisting of total body irradiation (TBI)-based conditioning regimen and a peripheral blood CD34+ cell graft combined with the adoptive transfer of naturally occurring regulatory T cells (Tregs) and conventional T cells (Tcons). No post-transplant pharmacologic GvHD prophylaxis was given. Such protocol was associated with low GvHD and relapse rate (Martelli et al., Blood 2014). To further reduce leukemia relapse in Treg/Tcon-based haploidentical HSCT (Treg/Tcon haplo-HSCT) we used high dose hyper-fractionated TBI (HF-TBI) in the conditioning regimen. We also extended Treg/Tcon haplo-HSCT to patients that are unfit (because of previous comorbidities) and/or too old to withstand high intensity regimens. In these patients the extra-hematologic toxicity of irradiation was reduced with the use of targeted total marrow and lymph node irradiation (TMLI). 40 patients with high risk acute leukemia (36 AML, 4 ALL) received Treg/Tcon haplo-HSCT. All but 3 patients were transplanted in complete remission. 12 younger patients (median age: 28, range: 20-43) received HF-TBI, while 28 older or unfit patients (59, 40-70) received TMLI in the conditioning regimen. HF-TBI (14.4 Gy) was administered in 12 fractions, 3 times a day for 4 days. TMLI was administered by means of Helical Tomotherapy HI-ART (9 fractions, 2 times a day for 4.5 days). Irradiation was followed by chemotherapy with Thiotepa, Fludarabine, and Cyclophosphamide. 2 × 106/kg freshly isolated CD4+CD25+FOXP3+ Tregs were transferred 4 days before the infusion of 1 × 106/kg Tcons and a mega-dose of CD34+ hematopoietic stem cells. No post-transplant pharmacologic GvHD prophylaxis was given. 38/40 patients engrafted. 12 (31%) developed aGvHD grade ³2 (10 are alive and off-therapy). 6 (16%) died because of transplant related complications (2 because of aGvHD, 2 infections, 1 veno-occlusive disease, 1 intracranial hemorrhage). Strikingly, despite the high risk diseases, no patient relapsed after a median follow up of 13 months (range 1-36, Fig. A). Further, only 1 patient developed cGvHD. Thus, cGvHD/Leukemia-free survival was 82% (Fig. B). Treg adoptive transfer allows for the safe infusion of an otherwise lethal dose of donor alloreactive Tcons in the absence of any other form of immune suppression. Our results demonstrate that the potent graft versus leukemia effect of Treg/Tcon adoptive transfer was boosted by high dose marrow irradiation. Thus, this study proves that the right combination of haploidentical Treg/Tcon immunotherapy plus a powerful conditioning regimen can fully eradicate leukemia