Free-electron lasing with compact beam-driven plasma wakefield accelerator.

The possibility to accelerate electron beams to ultra-relativistic velocities over short distances by using plasma-based technology holds the potential for a revolution in the field of particle accelerators1-4. The compact nature of plasma-based accelerators would allow the realization of table-top machines capable of driving a free-electron laser (FEL)5, a formidable tool to investigate matter at the sub-atomic level by generating coherent light pulses with sub-ångström wavelengths and sub-femtosecond durations6,7. So far, however, the high-energy electron beams required to operate FELs had to be obtained through the use of conventional large-size radio-frequency (RF) accelerators, bound to a sizeable footprint as a result of their limited accelerating fields. Here we report the experimental evidence of FEL lasing by a compact (3-cm) particle-beam-driven plasma accelerator. The accelerated beams are completely characterized in the six-dimensional phase space and have high quality, comparable with state-of-the-art accelerators8. This allowed the observation of narrow-band amplified radiation in the infrared range with typical exponential growth of its intensity over six consecutive undulators. This proof-of-principle experiment represents a fundamental milestone in the use of plasma-based accelerators, contributing to the development of next-generation compact facilities for user-oriented applications9.

Guiding of Charged Particle Beams in Curved Plasma-Discharge Capillaries.

We present a new approach that demonstrates the deflection and guiding of relativistic electron beams over curved paths by means of the magnetic field generated in a plasma-discharge capillary. We experimentally prove that the guiding is much less affected by the beam chromatic dispersion with respect to a conventional bending magnet and, with the support of numerical simulations, we show that it can even be made dispersionless by employing larger discharge currents. This proof-of-principle experiment extends the use of plasma-based devices, that revolutionized the field of particle accelerators enabling the generation of GeV beams in few centimeters. Compared to state-of-the-art technology based on conventional bending magnets and quadrupole lenses, these results provide a compact and affordable solution for the development of next-generation tabletop facilities.

Stable Operation of a Free-Electron Laser Driven by a Plasma Accelerator.

The breakthrough provided by plasma-based accelerators enabled unprecedented accelerating fields by boosting electron beams to gigaelectronvolt energies within a few centimeters [1-4]. This, in turn, allows the realization of ultracompact light sources based on free-electron lasers (FELs) [5], as demonstrated by two pioneering experiments that reported the observation of self-amplified spontaneous emission (SASE) driven by plasma-accelerated beams [6,7]. However, the lack of stability and reproducibility due to the intrinsic nature of the SASE process (whose amplification starts from the shot noise of the electron beam) may hinder their effective implementation for user purposes. Here, we report a proof-of-principle experiment using plasma-accelerated beams to generate stable and reproducible FEL light seeded by an external laser. FEL radiation is emitted in the infrared range, showing the typical exponential growth of its energy over six consecutive undulators. Compared to SASE, the seeded FEL pulses have energies 2 orders of magnitude larger and stability that is 3 times higher.

Longitudinal Phase-Space Manipulation with Beam-Driven Plasma Wakefields.

The development of compact accelerator facilities providing high-brightness beams is one of the most challenging tasks in the field of next-generation compact and cost affordable particle accelerators, to be used in many fields for industrial, medical, and research applications. The ability to shape the beam longitudinal phase space, in particular, plays a key role in achieving high-peak brightness. Here we present a new approach that allows us to tune the longitudinal phase space of a high-brightness beam by means of plasma wakefields. The electron beam passing through the plasma drives large wakefields that are used to manipulate the time-energy correlation of particles along the beam itself. We experimentally demonstrate that such a solution is highly tunable by simply adjusting the density of the plasma and can be used to imprint or remove any correlation onto the beam. This is a fundamental requirement when dealing with largely time-energy correlated beams coming from future plasma accelerators.

Focusing of High-Brightness Electron Beams with Active-Plasma Lenses.

Plasma-based technology promises a tremendous reduction in size of accelerators used for research, medical, and industrial applications, making it possible to develop tabletop machines accessible for a broader scientific community. By overcoming current limits of conventional accelerators and pushing particles to larger and larger energies, the availability of strong and tunable focusing optics is mandatory also because plasma-accelerated beams usually have large angular divergences. In this regard, active-plasma lenses represent a compact and affordable tool to generate radially symmetric magnetic fields several orders of magnitude larger than conventional quadrupoles and solenoids. However, it has been recently proved that the focusing can be highly nonlinear and induce a dramatic emittance growth. Here, we present experimental results showing how these nonlinearities can be minimized and lensing improved. These achievements represent a major breakthrough toward the miniaturization of next-generation focusing devices.

Signatures of the Self-Similar Regime of Strongly Coupled Stimulated Brillouin Scattering for Efficient Short Laser Pulse Amplification.

Plasma-based laser amplification is considered as a possible way to overcome the technological limits of present day laser systems and achieve exawatt laser pulses. Efficient amplification of a picosecond laser pulse by stimulated Brillouin scattering (SBS) of a pump pulse in a plasma requires to reach the self-similar regime of the strongly coupled (SC) SBS. In this Letter, we report on the first observation of the signatures of the transition from linear to self-similar regimes of SC-SBS, so far only predicted by theory and simulations. With a new fully head-on collision geometry, subpicosecond pulses are amplified by a factor of 5 with energy transfers of few tens of mJ. We observe pulse shortening, frequency spectrum broadening, and down-shifting for increasing gain, signatures of SC-SBS amplification entering the self-similar regime. This is also confirmed by the power law dependence of the gain on the amplification length: doubling the interaction length increases the gain by a factor 1.4. Pump backward Raman scattering (BRS) on SC-SBS amplification has been measured for the first time, showing a strong decrease of the BRS amplitude and frequency bandwidth when SBS seed amplification occurs.

Acceleration and focusing of relativistic electron beams in a compact plasma device.

Plasma wakefield acceleration represented a breakthrough in the field of particle accelerators by pushing beams to gigaelectronvolt energies within centimeter distances. The large electric fields excited by a driver pulse in the plasma can efficiently accelerate a trailing witness bunch paving the way toward the realization of laboratory-scale applications like free-electron lasers. However, while the accelerator size is tremendously reduced, upstream and downstream of it the beams are still handled with conventional magnetic optics with sizable footprints and rather long focal lengths. Here we show the operation of a compact device that integrates two active-plasma lenses with short focal lengths to assist the plasma accelerator stage. We demonstrate the focusing and energy gain of a witness bunch whose phase space is completely characterized in terms of energy and emittance. These results represent an important step toward the accelerator miniaturization and the development of next-generation table-top machines.

Harmonic Focus Versus Conventional Electrocautery for Femoral Artery Exposure: a "Direct" Comparison on the Same Patients.

Surgical access complications during endovascular aneurysm repair (EVAR) are reported relatively frequent. HARMONIC FOCUS® (HF; Ethicon Endo-Surgery Inc., Cincinnati, Ohio, USA) is a device developed to improve bleeding control and reduce heat-related damage stemming from surgical preparation. The aim of this study was to evaluate outcomes and safety of HF versus conventional haemostasis with electrocautery, both techniques used in the same patient. Five patients developed bilateral wound's thickening (13.9%) demonstrated at the CT scan, two of whom had no clinical manifestation while in three cases the thickening was associated with lymphocele (4.54%), 2 of which were in the side where the EC was used (5.5%), and 1 case (2.7%), in the HF applied side. One isolated lymphocele occurred at the left groin (2.7%) (tables n.2-3). A Fisher's exact test was conducted between EC and HF on the occurrence of wound healing complications (3/36 for EC and 1/36 for HF) that resulted statistically significant at p<0.05. Focus Harmonic Scalpel has certain advantages than conventional haemostasis in avoiding surgical access complications.

Early Results of Mechanochemical Ablation with Flebogrif® in great Saphenous Vein Insufficiency: does Polidocanol Concentration Affect Outcome?

BACKGROUND: Flebogrif® (Balton, Poland) is a novel mechanochemical ablation (MOCA) device for saphenous vein insufficiency. It combines endothelial damage performed by radial retractable cutting hooks together with chemical ablation through sclerosant injection of 3% polidocanol foam according to its IFU. The objective of this study is to evaluate Flebogrif's efficacy in terms of recanalization rate and recurrence by varying polidocanol foam concentrations. METHODS: We performed 24 MOCAs on 23 patients with Flebogrif® between January and May 2019. In 12 cases the polidocanol foam was prepared at a 3% concentration, and in another 12 at 1.5%. Great saphenous vein (GSV) recanalization and truncular recurrence were evaluated at 1 and 3 months with a Duplex Ultrasound Anatomy (DUS) examination. RESULTS: At 1- and 3-month follow-ups, none of the 14 patients treated with the polidocanol 3% foam were observed to have had great saphenous vein GSV recanalization and truncular recurrence. Only 2 of the 14 (14.3%) cases treated with polidocanol 1.5% foam showed evidence of recanalization within the first centimetres from the sapheno-femoral junction (p > .05). All patients experienced clinical benefits without recurrence of symptoms. CONCLUSION: MOCA with Flebogrif® is a safe, relatively inexpensive and effective alternative to standard methods in the treatment of saphenous insufficiency with encouraging short-term results. Despite our relatively small patient sample, no statistical significance in evidence of recurrence in the group of patients treated with 3% foam and those treated with 1.5% foam was noted. Longer term analysis of GSV patency and recurrence is necessary to further evaluate Flebogrif's impact and actual indications in the treatment of chronic venous disease.

Standard Carotid Endarterectomy versus Carotid Artery Stenting with Closed-Cell Stent Design and Distal Embolic Protection: does the age matter?

Carotid artery endarterectomy (CEA) is considered the gold standard for treatment of symptomatic and asymptomatic carotid disease. Carotid artery stenting (CAS) is a less invasive approach and therefore could be considered a viable alternative to CEA, especially in high-risk patients or those with relative contraindications to CEA (i.e. actinic stenosis, post-CEA restenosis, previous neck or tracheostomy surgery, contralateral laryngeal nerve paralysis, etc.). METHODS: The aim of this study is to evaluate the short- and medium-term outcomes of CAS performed with a single type of closed-cell stent design and distal filter protection by comparing the procedure with CEA based upon 3 endpoints: overall survival rate, stroke free survival rate and restenosis free survival rate.The same endpoints were also evaluated in 2 different age groups, more and less than 70 years, to show possible age-based differences on outcomes.Among 105 patients (77 males, 28 females), 74 were submitted to CEA and 31 were subject to CAS.In all cases the same self-expanding stent with closed-cell design (XACT Carotid Stent, Abbott Vascular) and the same distal embolic protection device (Emboshield NAV, Abbott Vascular) were employed. RESULTS: At 12 months, no statistically significant difference was observed in overall survival rates (CEA 93.2% vs CAS 93.5%, p=0.967) and restenosis free survival rates (CEA 94.5% vs CAS 96.8%, p=0.662).An increased stroke free survival rate was observed in the CEA group when compared to the CAS group (CEA 100.0% vs CAS 93.5%, p=0.028).The age-based endpoints didn't show any significant difference. CONCLUSION: These results suggest that CEA still remains the gold standard of treatment for carotid stenosis given its greater efficacy in the prevention of stroke CAS. However, CAS could be considered as an alternative treatment to CEA to be used in select cases only.

Treatment of de novo femoro-popliteal lesions with a new Drug Coated Balloon: early experience of a single Center in the first 50 patients.

Angioplasty with drug-coated balloon (DCB) is an emerging and reliable method for the treatment of femoro-popliteal lesions. We report our experience with the Stellarex™ DCB in the first 50 patients. METHODS: From July 2015 to November 2017, 50 patients (41 M, 9F), medium age (64 ± 7.4 year) were subject to 33 angioplasties (PTAs) for femoro-popliteal lesions with a paclitaxel-coated balloon (Stellarex™). Based upon clinical data sixteen patients had severe claudication (56% - Rutherford class 3); ten patients suffered from ischemic rest pain (34% - Rutherford class 4); and five presented minor tissue loss (10% - Rutherford class 5). 42% of patients showed femoro-popliteal lesion TASC-II B, and 58% presented lesions pertaining to TASC-II C. RESULTS: Immediate technical success was 100% without perioperative complications. Primary patency rate was 94% at twelve months. In three cases restenosis (6%) was detected within a year from procedure, and a further PTA DCB was performed with primary assisted patency rates of 100% at twelve months. Two patients underwent major lower limb amputation. Three patients died during follow-up and one patient was lost at follow-up. CONCLUSION: DCB angioplasty with Stellarex™ is a viable alternative to traditional endovascular procedures proving satisfactory primary patency rates at twelve months. Based on our experience, treatment with DCB is a first choice technique for non-complex de novo lesions of the femoro - popliteal tract.

Endovascular management of a large hepatic artery aneurysm.

Visceral arteries aneurysms (VAA) are an increasingly interesting clinical entity due to their challenging diagnosis and treatment options. The more prevalent use and accuracy of enhanced imaging techniques such as ultrasonography and computed tomography have increased the frequency of diagnosis of aneurysmal degeneration of the visceral arteries. Despite there is no statistically significant difference in terms of overall mortality and post-operative complications between endovascular therapy and open repair, interventional strategies present a significantly lower length of stay and less invasiveness and should be preferred in elderly patients, or in case of co-morbidity and poor candidates for surgery. We herein describe the case of a 79-year-old male who presented a common hepatic artery aneurism (CHAA), involving aberrant visceral arteries anatomy.

Chest pain due to Pinch-off syndrome: radiological findings and endovascular rescue.

Port-a-cath is widely used as a route for administration of drugs in hematology and oncology patients and, recently, has been adapted also for hemodialysis patients. Major complications include infection, thrombosis, arrhythmia, and embolization. The Pinch-off-syndrome (POS) means the clavicle and the first rib compress the long-term central venous catheter. The reported incidence rate ranges from 1.4% to 4.1%. This syndrome can be recognized on chest radiography by observing a thinning of the catheter lumen through the passage between the clavicle and the first rib. Catheter fracture is a rare but potentially life-threatening complication that must be recognized and treated promptly. Management of dislodged ports includes percutaneous transcatheter retrieval, open thoracotomy retrieval and oral anticoagulant therapy. Among these techniques, percutaneous transcatheter retrieval is an easy, safe and efficient method. We report the successful percutaneous endovascular retrieval of dislodged intracardiac catheter, separated from its port, in a 58 year-old male patient who presented with chest pain.

Successful endovascular treatment of a 13 cm abdominal aortic aneurysm. Case report.

There is increasing evidence in the literature that endovascular aneurysm repair is the first-line approach for most of abdominal aortic aneurysms (AAAs). Furthermore aortouniiliac stent graft placement is, in high risk patients or during emergency setting, a safe procedure over the mid- and long-term period and compares well with the results of bifurcated stent grafts. We present a case of a 66 -year-old gentleman, with pneumothorax after therapeutic thoracentesis and a giant AAA, successfully treated with an aortomonoiliac stent grafting and femoro-femoral crossover bypass.