High energy implementation of coil-target scheme for guided re-acceleration of laser-driven protons.

Developing compact ion accelerators using intense lasers is a very active area of research, motivated by a strong applicative potential in science, industry and healthcare. However, proposed applications in medical therapy, as well as in nuclear and particle physics demand a strict control of ion energy, as well as of the angular and spectral distribution of ion beam, beyond the intrinsic limitations of the several acceleration mechanisms explored so far. Here we report on the production of highly collimated ([Formula: see text] half angle divergence), high-charge (10s of pC) and quasi-monoenergetic proton beams up to [Formula: see text] 50 MeV, using a recently developed method based on helical coil targetry. In this concept, ions accelerated from a laser-irradiated foil are post-accelerated and conditioned in a helical structure positioned at the rear of the foil. The pencil beam of protons was produced by guided post-acceleration at a rate of [Formula: see text] 2 GeV/m, without sacrificing the excellent beam emittance of the laser-driven proton beams. 3D particle tracing simulations indicate the possibility of sustaining high acceleration gradients over extended helical coil lengths, thus maximising the gain from such miniature accelerating modules.

Guided post-acceleration of laser-driven ions by a miniature modular structure.

All-optical approaches to particle acceleration are currently attracting a significant research effort internationally. Although characterized by exceptional transverse and longitudinal emittance, laser-driven ion beams currently have limitations in terms of peak ion energy, bandwidth of the energy spectrum and beam divergence. Here we introduce the concept of a versatile, miniature linear accelerating module, which, by employing laser-excited electromagnetic pulses directed along a helical path surrounding the laser-accelerated ion beams, addresses these shortcomings simultaneously. In a proof-of-principle experiment on a university-scale system, we demonstrate post-acceleration of laser-driven protons from a flat foil at a rate of 0.5 GeV m(-1), already beyond what can be sustained by conventional accelerator technologies, with dynamic beam collimation and energy selection. These results open up new opportunities for the development of extremely compact and cost-effective ion accelerators for both established and innovative applications.

Role of plaque calcification regulators osteoprotegerin and matrix Gla-proteins in stable angina and acute myocardial infarction.

AIM: To assess serum levels of the plaque calcification regulators osteoprotegerin (OPG) and Matrix Gla-proteins (MGP) in individuals with stable angina and acute myocardial infarction submitted to coronary angiography and their relation to coronary artery disease burden. METHODS: The study included 40 individuals affected by ST-elevation myocardial infarction (STEMI) and 40 individuals with stable angina who all underwent coronary angiography, with evaluation of the extent of coronary artery disease by Syntax Score calculation and measurement of serum OPG and MGP levels. Osteoporosis was excluded by femoral and vertebral computerized bone mineralometry. RESULTS: Serum OPG and MGP levels were respectively 3.87 ±â€Š1.07 pmol/l and 6.80 ±â€Š2.43 nmol/l in the stable angina group, 7.57 ±â€Š1.5 pmol/l and 7.18 ±â€Š1.93 nmol/l in the STEMI group (P < 0.01 and P = 0.33, respectively). Pearson correlation coefficient for OPG and Syntax Score, MGP and Syntax score was respectively 0.79 (P < 0.01) and 0.18 (P = 0.22) in the stable angina group, -0.03 (P = 0.43) and 0.10 (P = 0.5) in the STEMI group.Serum OPG and MGP levels were respectively 5.52 ±â€Š1.02 pmol/l and 7.56 ±â€Š1.42 nmol/l in diabetics, 4.3 ±â€Š0.8 pmol/l and 6.52 ±â€Š1.14 nmol/l in nondiabetics (P < 0.05; P < 0.05). CONCLUSION: OPG, in a relatively small group of patients with stable angina, correlates proportionally with the extent of coronary artery disease (CAD), as evaluated by the Syntax Score. Higher serum OPG levels can be observed in individuals with STEMI regardless of CAD burden. As for MGP, a potential role as marker of plaque calcification remains unproven.

A 'clover' coronary artery: role of coronary computed tomography to indicate optimal treatment in aneurysmal coronary artery disease.

We report the case of a 61-year-old man referred to our department for exertional angina with a history of tri-vessel aneurysmal coronary artery disease. Exercise stress echocardiography was positive for inferior wall hypokinesia. Coronary computed tomography (CT) provided a more accurate characterization of the coronary aneurysms. It detected a laminated thrombus of the proximal left anterior descending and a clover-like aneurysmal dissection of the proximal right coronary artery, which questioned the feasibility of coronary angioplasty. So, the patient was treated with medical therapy only. This case confirmed the importance of coronary CT as diagnostic tool for procedural risk assessment and definition of the most appropriate treatment in patients with coronary aneurysms.

Solitary versus shock wave acceleration in laser-plasma interactions.

The excitation of nonlinear electrostatic waves, such as shock and solitons, by ultraintense laser interaction with overdense plasmas and related ion acceleration are investigated by numerical simulations. Stability of solitons and formation of shock waves is strongly dependent on the velocity distribution of ions. Monoenergetic components in ion spectra are produced by "pulsed" reflection from solitary waves. Possible relevance to recent experiments on "shock acceleration" is discussed.

Unrepaired tetralogy of fallot in an 85-year-old man.

Tetralogy of Fallot is the most common cyanotic congenital heart defect and accounts for about 5% of all congenital cardiopathies. The definitive treatment modality for tetralogy of Fallot is reparative surgery, which is recommended to be performed by the time of diagnosis. Without surgical repair, most patients would die during their childhood. In the past, survival data indicated that 66% of persons with tetralogy of Fallot not surgically treated lived until the age of 1, 49% lived until the age of 3, and 24% lived until the age of 10. We now present a rare case of a man with unrepaired tetralogy of Fallot who survived until the age of 85. He presented to our emergency room for dyspnea and palpitations due to a new-onset high-frequency atrial fibrillation and acute heart failure; transthoracic echocardiography showed the presence of tetralogy of Fallot. By consulting the scientific literature, we can say that this is the second patient who survived more than 80 years without surgical intervention.

An unusual case of acute coronary syndrome late after stent implantation.

We report a case of a 66-year-old Caucasian male who presented to our department with unstable angina in July 2011. He had a medical history of trivessel coronary artery disease and underwent several percutaneous coronary interventions (2003, 2004, and 2006). The latest coronary angiography, performed in January 2011, showed mild intimal hyperplasia within the proximal left anterior descending segment, treated with a sirolimus-eluting stent in 2003. On admission, electrocardiogram was positive for a recent acute coronary syndrome, so the patient underwent coronary angiography, which showed proximal left anterior descending stent thrombosis, occurred eight years after drug-eluting stent implantation. Intravascular ultrasound revealed a soft plaque rupture within the stented segment, which was the cause of stent thrombosis. So the lack of endothelialization over stent struts is not the only mechanism determining acute coronary syndromes late after stent implantation. In-stent neoatherosclerosis, frequently disregarded, is another possible actor especially of very late thrombotic events. However, the pathogenesis of this phenomenon has not been clearly established.

Recurrent angina after coronary angioplasty: mechanisms, diagnostic and therapeutic options.

Recurrent angina in patients who underwent percutaneous coronary intervention is defined as recurrence of chest pain or chest discomfort. Careful assessment is recommended to differentiate between non-cardiac and cardiac causes. In the case of the latter, recurrent angina occurrence can be related to structural ('stretch pain', in-stent restenosis, in-stent thrombosis, incomplete revascularization, progression of coronary atherosclerosis) or functional (coronary micro-vascular dysfunction, epicardial coronary spasm) causes. Even though a complete diagnostic algorithm has not been validated, ECG exercise testing, stress imaging and invasive assessment of coronary blood flow and coronary vaso-motion (i.e. coronary flow reserve, provocation testing for coronary spasm) may be required. When repeated coronary revascularization is not indicated, therapeutic approaches should aim at targeting the underlying mechanism for the patient's symptoms using a variety of drugs currently available such as beta-blockers, calcium-channel blockers, ivabradine or ranolazine.

"Light sail" acceleration reexamined.

The dynamics of the acceleration of ultrathin foil targets by the radiation pressure of superintense, circularly polarized laser pulses is investigated by analytical modeling and particle-in-cell simulations. By addressing self-induced transparency and charge separation effects, it is shown that for "optimal" values of the foil thickness only a thin layer at the rear side is accelerated by radiation pressure. The simple "light sail" model gives a good estimate of the energy per nucleon, but overestimates the conversion efficiency of laser energy into monoenergetic ions.

Laser acceleration of ion bunches at the front surface of overdense plasmas.

The acceleration of ions in the interaction of high intensity laser pulses with overdense plasmas is investigated with particle-in-cell simulations. For circular polarization of the laser pulses, high-density ion bunches moving into the plasma are generated at the laser-plasma interaction surface. A simple analytical model accounts for the numerical observations and provides scaling laws for the ion bunch energy and generation time as a function of pulse intensity and plasma density.

Erectile dysfunction prevalence, time of onset and association with risk factors in 300 consecutive patients with acute chest pain and angiographically documented coronary artery disease.

OBJECTIVES: The aim of this study was to assess erectile dysfunction prevalence, time of onset and association with risk factors in patients with acute chest pain and angiographically documented coronary artery disease. METHODS: 300 consecutive patients with acute chest pain and angiographically documented coronary artery disease were assessed using a semi-structured interview investigating their medical and sexual histories, the International Index of Erectile Function and other instruments. RESULTS: Patient mean age was 62.5+/-8 years (range 33-86 years). Mean duration of symptoms or signs of myocardial ischaemia prior to enrollment in the study was 49 months (range 1-200). Coronary angiography showed 1-, 2- and 3-vessel disease in 98 (32.6%), 88 (29.3%) and 114 (38%) patients, respectively. The prevalence of ED among all patients was 49% (147/300). Erectile dysfunction was scored as mild, mild to moderate, moderate and severe in 21 (14%), 31 (21%), 20 (14%), and 75 (51%) of patients, respectively. There was no significant difference between patients with ED (n=147) or without ED (n=153) as far as clinical and angiographic characteristics were concerned. In the 147 patients with co-existing ED and CAD, ED symptoms were reported as having become clinically evident prior to CAD symptoms by 99/147 (67%) patients. The mean time interval between the onset of ED and CAD was 38.8 months (range 1-168). There was no significant difference in terms of risk factor distribution and clinical and angiographic characteristics between patients with the onset of ED before vs. after CAD diagnosis. Interestingly, all patients with type I diabetes and ED actually developed sexual dysfunction before CAD onset (p<0.001). CONCLUSIONS: Our study suggests that a significant proportion of patients with angiographically documented coronary artery disease have erectile dysfunction and that this latter condition may become evident prior to angina symptoms in almost 70% of cases. Future studies including a control group of patients with coronary artery disease and normal erectile function are required in order to verify whether erectile dysfunction may be considered a real predictor of ischemic heart disease.