Data on the design optimization, indoor characterization and outdoor testing of GaAs/Bifacial Si heterojunction four-terminal photovoltaic systems.

The development of a highly efficient multijunction technology is a key challenge for the future of photovoltaic and for the transition to more renewable energy sources. In this scenario, four-terminal architecture (4T) compared to the classic tandem design allows a large intrinsic robustness to the variations of the solar spectrum, which continuously occur under normal outdoor operation conditions. On the other hand, bifacial solar cells and modules have already proven to be able to increase the energy yield of solar farms at reduced costs. For these reasons, a thorough investigation of the compatibility between these two solutions has been performed by combining a III-V semiconductor with the silicon heterojunction technology in a four-terminal device. This work has been designed in support of the research article entitled "Outdoor performance of GaAs/Bifacial Si Heterojunction four-terminal system using optical spectrum splitting" [1], which showed, through data modeling and an accurate daily analysis of the spectral distribution of solar light, how a four-terminal architecture guarantees the consistency of the bifacial gain and more robust performances than a two-terminal system. Here additional data on the manufacturing, optimization and characterization of the device are presented.

Numerical Verification of an Analytical Model for Phase Noise in MEMS Oscillators.

A new analytical formulation for phase noise in MEMS oscillators was recently presented encompassing the role of essential nonlinearities in the electrical and mechanical domains. In this paper, we validate the effectiveness of the proposed analytical formulation with respect to the unified theory developed by Demir et al. describing phase noise in oscillators. In particular, it is shown that, over a range of the second-order mechanical nonlinear stiffness of the MEMS resonator, both models exhibit an excellent match in the phase diffusion coefficient calculation for a square-wave MEMS oscillator.

Coronary artery aneurysms: case report and treatment overview.

Coronary artery aneurysms (CAAs) are localized dilatations exceeding the diameter of adjacent normal coronary segments. These conditions, even rare, still represent an important risk factor for the patient life.

Tramadol and 0.5% levobupivacaine for single-shot interscalene block: effects on postoperative analgesia in patients undergoing shoulder arthroplasty.

BACKGROUND: The aim of this study was to evaluate the efficacy of tramadol as an adjuvant to the local anaesthetic solution in patients undergoing shoulder arthroscopy for rotator cuff tear after middle interscalene block (MIB). METHODS: We enrolled 120 patients (ASA I-II), scheduled for arthroscopic surgery for rotator cuff tear. The patients were sedated with midazolam 0.02 mg/kg and haloperidol 2 mg i.v. before performing MIB. All subjects underwent a MIB with 0.4 mL/kg of 0.5% levobupivacaine. After computerized randomization, all patients were allocated in 1 of 3 groups, each including 40 subjects. Group Placebo (Group P) received 0.4 mL/kg of 0.5% levobupivacaine plus isotonic sodium chloride for MIB and isotonic sodium chloride i.m. Group "Perineural Tramadol" (Group TPN) received 0.4 ml/Kg of 0.5% levobupivacaine plus 1.5 mg/kg of tramadol perineurally and isotonic sodium chloride i.m. Group "Intramuscular Tramadol" (Group TIM) received 0.4 ml/Kg of 0.5% levobupivacaine plus isotonic sodium chloride perineurally and 1.5 mg/kg of tramadol i.m. RESULTS: The MIB onset times were not statistically different in the three groups. The duration of analgesia was significantly longer in Groups TPN and TIM, where tramadol was administered, either i.m. or perineurally, compared with the placebo group. A significant statistical difference was found in the duration of analgesia between the group TPN and TIM. CONCLUSION: The addition of tramadol to the local anaesthetic solution administered for MIB provided a longer duration of analgesia compared with placebo and i.m tramadol administration in patients undergoing arthroscopic surgery for rotator cuff tear.

Neoplastic superior vena cava obstruction: combined approach.

Primary adult cardiac tumors are rare entities with a low indices. In 90% of cases are benign. Among malignant tumors angiosarcomas are the most common. In 80% of cases they arises in the right atrium, more often in younger males as compared to benign tumors. The majority of them manifests as locally already advanced disease, precluding macroscopically complete surgical resection. Moreover, the presence of macro- and micrometastasis makes the prognosis always prohibitive. The duration of symptoms is in the order of months and the median survival ranges from 6 to 11 months. Death cause is usually a complication of locally recurrent disease: tamponade, hemopericardium are common. Treatment is multidisciplinary. The combination of chemo- and radiotherapy with surgery aims to increase survival. In the management of unresectable tumors, due to anatomic reason or Iocoregional spread, an important role is played by pre-operatory chemotherapy or chemo-radiation to increase short term survival.

Perioperative use of tirofiban hydrochloride (Aggrastat) does not increase surgical bleeding after emergency or urgent coronary artery bypass grafting.

BACKGROUND: The platelet glycoprotein IIb/IIIa inhibitor tirofiban hydrochloride improves outcome in patients with acute coronary syndrome. Nevertheless, a considerable number of patients require emergency or urgent coronary artery bypass grafting and may be at increased risk of postoperative bleeding after treatment with this molecule. The aim of this study is to evaluate the incidence of bleeding complications among patients undergoing bypass grafting after treatment with tirofiban. METHODS: We investigated the influence of the molecule on postoperative bleeding after cardiac surgery, comparing 2 groups of patients undergoing emergency or urgent coronary artery bypass grafting: group A (n = 20) received tirofiban, and group B (n = 68) received conventional therapy with intravenous heparin up until the operation. A total of 88 patients underwent coronary artery bypass surgery within 2 hours of ceasing the hemodynamic study. Clinical outcome, chest tube outputs, bleeding complications, transfusion requirements, platelet and hemoglobin counts, and clinical complications were examined. RESULTS: Bleeding differences were noted between the 2 groups at 8, 16, and 24 hours postoperatively. The incidence of blood, platelet, and fresh frozen plasma transfusions was higher in the control group. Postoperative thrombocytopenia was preserved in group A (199.5 +/- 70.4 vs 150.6 +/- 33.4 10(3)/mL, P <.01). No significant differences were noted between the 2 groups in the incidence of perioperative myocardial infarction, but significant differences were noted in enzyme levels, length of stay in the intensive care unit, and length of stay in the hospital. No deaths were observed. Hospital morbidity was increased in group B because of factors that were not apparently linked with tirofiban infusion. CONCLUSIONS: Patients may safely undergo coronary artery bypass surgery after treatment with tirofiban hydrochloride. This molecule, administered in the immediate preoperative period, has no adverse clinical effects and does not seem to negatively influence the incidence of perioperative myocardial infarction. Although extracorporeal circulation can modify platelet numbers and function, our ongoing data could show significant reduction in the loss of platelets induced by cardiopulmonary bypass, minor postoperative bleeding, and a minor transfusion requirement in general.

A primary intracavitary right atrial neurilemoma.

Primary cardiac neurilemoma, a benign tumor, is extremely uncommon. To our knowledge only eight cases have been reported in the literature. We report a case of a 72-year-old man who presented with complaints of progressive shortness of breath and chest pain, seven years after a right nephrectomy for renal adenocarcinoma. An intra-right atrial tumor was surgically removed; the lesion was found to be a neurilemoma of the right atrium. This case report describes the surgical removal and rarity of neurilemomas, their predisposition to be right-sided in the heart and their coincidental association with other types of cancer.

Localised hypertrophy of semimembranous muscle. A report of two cases in athletes.

We report two cases of localised hypertrophy of semimembranous muscle in young athletes diagnosed with ultrasonography, flow color-Doppler and MRI. The symptomatic case had the resolution of the pain after one month rest. At one year follow-up both cases are still asymptomatic, without any further increase of the hypertrophyc masses.

The properties of the pacemaker current I(F)in human ventricular myocytes are modulated by cardiac disease.

The pacemaker current I(f)is present in ventricular myocytes from the human failing heart where it may contribute to arrhythmogenesis. The role of cardiac disease in the modulation of I(f)expression is still uncertain. We studied the functional expression and properties of I(f)in human ventricular myocytes isolated from control donor hearts or from explanted failing hearts of patients with ischemic and dilated cardiomyopathy. In patch-clamped cells, I(f)was elicited by hyperpolarization. Membrane capacitance (C(m)) was significantly higher in dilated cardiomyopathy than in control or ischemic cardiomyopathy. I(f)was present in all ischemic and dilated cardiomyopathy tested cells and in 76% of control cells. In ischemic and dilated cardiomyopathy, I(f)amplitude measured at -120 mV was significantly greater than in control. However, I(f)density (i.e. current normalized to C(m)) was significantly higher in ischemic cardiomyopathy (2.0+/-0.2 pA/pF) than in dilated cardiomyopathy (1.2+/-0.1 pA/pF) or control (1.0+/-0.1 pA/pF). In diseased hearts, the activation curve was significantly shifted to more positive values compared to control. The slope of the fully-activated I-V relations was greater in ischemic cardiomyopathy than in dilated cardiomyopathy or control (P<0.05) while the intercept with the x -axis (V(rev)) was similar. In conclusion, I(f)is overexpressed in human ventricular myocytes from failing hearts; its functional expression seems related to the etiology of the disease, being higher in ischemic than in dilated cardiomyopathy, and not to the degree of cell hypertrophy.

Latrogenic injury to the longthoracic nerve: an underestimated cause of morbidity after cardiac surgery.

After heart surgery, complications affecting the brachial plexus have been reported in 2% to 38% of cases. The long thoracic nerve is vulnerable to damage at various levels, due to its long and superficial course. This nerve supplies the serratus anterior muscle, which has an important role in the abduction and elevation of the superior limb; paralysis of the serratus anterior causes "winged scapula," a condition in which the arm cannot be lifted higher than 90 degrees from the side. Unfortunately the long thoracic nerve can be damaged by a wide variety of traumatic and nontraumatic occurrences, ranging from viral or nonviral disease to improper surgical technique, to the position of the patient during transfer to a hospital bed. Our patient, a 62-year-old man with triple-vessel disease, underwent myocardial revascularization in which right and left internal thoracic arteries and the left radial artery were grafted to the right coronary, descending anterior, and obtuse marginal arteries, respectively. Despite strong recovery and an apparently good postoperative course, the patient sued for damages due to subsequent winging of the left scapula. In this instance, the legal case has less to do with the cause of the lesion (which remains unclear) than with failure to adequately inform the patient of possible complications at the expense of the nervous system. The lesson is that each patient must receive detailed written and oral explanation of the potential benefits and all conceivable risks of a procedure.

A simple method to prevent calcium embolization during aortic valve surgery.

Calcium embolization is a potential complication of aortic valve surgery Handling and debridement of calcified structures may lead to dislodgment of particles, which can fall into the left ventricular chamber With restoration of the heartbeat, these particles are ejected into the systemic circulation, with subsequent peripheral or coronary embolism. We have developed a simple and safe method to prevent this condition; in our practice, we have found this method to be very effective.

A quantitative study of calcium deposition in the aortic wall following Medtronic Freestyle compared with homograft aortic root replacement. A prospective randomized trial.

BACKGROUND AND AIM OF THE STUDY: Unstented aortic valve substitutes offer many of the theoretical advantages of homografts such as superior hemodynamic performance and enhanced durability, particularly when inserted as a root. Many of these depend on the maintained flexibility of the valve components. Calcification of the aortic wall may adversely affect these phenomena. Electron beam computed tomography has been used to evaluate aortic wall calcification in patients undergoing aortic root replacement in a prospective randomized trial designed to compare the Medtronic Freestyle valve with the homograft valve replacement. METHODS: Patients were followed with electron beam computed tomography scans of the aortic root at six-monthly intervals after surgery. A calcification score (Hounsfield units) and a calcified volume score (mm3) were obtained from each scan using a new modified technique. Results were related to hemodynamic data from echocardiography. The prevalence of calcification was also related to the homograft donor age. RESULTS: Seventy-six patients (age range: 40-79 years) were randomized to root replacement with either homograft (n = 31) or Freestyle (n = 45) valves. Fifty-three scans of the aortic root were performed postoperatively in 37 patients. No statistical difference between the two groups was found at six and 12 months after surgery. However, after 18 months the calcified volume score was 5903.8+/-2356.8 mm3 in the homograft versus 2725.6+/-1500.5 mm3 in the Freestyle group (p = 0.017). There was a correlation between calcification score, calcified volume score and left ventricular mass (r = 0.323, p = 0.093 and r = 0.350, p = 0.068, respectively) on the one hand, and calcification score, calcified volume score and valve size on the other hand (r = 0.178, p = 0.466 and r = 0.068, p = 0.780, respectively). CONCLUSIONS: Electron beam computed tomography provides a powerful tool for the detection of calcium in the aortic wall of valve grafts. There is a low rate of calcification during the first 18 months in the Medtronic Freestyle valve, and this appears to be lower than that observed in homografts. Longer-term follow up of the aortic root in these patients is required. This is an ongoing study.

Myocardial ischemic injury and purine metabolism in patients undergoing coronary artery bypass.

OBJECTIVES: High-energy phosphates and their catabolic products were determined in myocardium during coronary artery bypass surgery with blood cardioplegic reperfusion in order to evaluate the effects of aortic cross-clamping and reoxygenation on myocardial purine metabolism. DESIGN AND METHODS: Transmural left ventricular biopsy specimens were taken with ITu-Cut biopsy needles, before aortic cross-clamping, before cross-clamp removal and after 30' of reperfusion; perchloric extracts of the material were analyzed for nucleotide content by capillary zone electrophoresis (CZE). The CZE procedure used separates the complete spectrum of purine metabolites in myocardial extracts obtained from 0.6-8.6 mg biopsy material. RESULTS: The basal values of ATP/ADP ratio and energy charge were low, IMP content was high. After the ischemic period, ATP levels further decreased and IMP, nucleosides and bases accumulated. After reperfusion, nucleoside and base basal levels, but not energy charge, were restored to some extent. CONCLUSIONS: The study arises the problem of myocardial preservation during heart surgery. In this investigation, capillary electrophoresis was an extremely adaptable technique for the evaluation of ischemic injury and could be useful in studying the effects of cardioplegic solutions.

[The observations in a case of eosinophilic fasciitis]. / Osservazioni su un caso di fascite eosinofila.

We present a typical case of eosinophilic fasciitis, with transient peripheral eosinophilia, indurative swelling of the legs, perivascular infiltrates of mononuclear cells and eosinophils of the subcutis and deep fascia, increased ESR, fever, anemia, complete response to steroids. We consider the literature on this topic, particularly concerning the following question: is eosinophilic fasciitis a distinct disease entity or a variant of scleroderma?

Non-Hodgkin's lymphoma and subsequent acute lymphoblastic leukaemia in a patient with polymyalgia rheumatica.

A patient presenting with polymyalgia rheumatica-like symptoms was found to have non-Hodgkin's lymphoma which later transformed into acute lymphoblastic leukaemia. The association of polymyalgia rheumatica-like symptoms and lymphoreticular/haematological malignancies is discussed.