1,849 research outputs found

    NEW APPROACHES FOR VERY SHORT-TERM STEADY-STATE ANALYSIS OF AN ELECTRICAL DISTRIBUTION SYSTEM WITH WIND FARMS

    Get PDF
    Distribution networks are undergoing radical changes due to the high level of penetration of dispersed generation. Dispersed generation systems require particular attention due to their incorporation of uncertain energy sources, such as wind farms, and due to the impacts that such sources have on the planning and operation of distribution networks. In particular, the foreseeable, extensive use of wind turbine generator units in the future requires that distribution system engineers properly account for their impacts on the system. Many new technical considerations must be addressed, including protection coordination, steady-state analysis, and power quality issues. This paper deals with the very short-term, steady-state analysis of a distribution system with wind farms, for which the time horizon of interest ranges from one hour to a few hours ahead. Several wind-forecasting methods are presented in order to obtain reliable input data for the steady-state analysis. Both deterministic and probabilistic methods were considered and used in performing deterministic and probabilistic load-flow analyses. Numerical applications on a 17-bus, medium-voltage, electrical distribution system with various wind farms connected at different busbars are presented and discusse

    Nonlinear heart rate variability features for real-life stress detection. Case study : students under stress due to university examination

    Get PDF
    Background: This study investigates the variations of Heart Rate Variability (HRV) due to a real-life stressor and proposes a classifier based on nonlinear features of HRV for automatic stress detection. Methods: 42 students volunteered to participate to the study about HRV and stress. For each student, two recordings were performed: one during an on-going university examination, assumed as a real-life stressor, and one after holidays. Nonlinear analysis of HRV was performed by using Poincaré Plot, Approximate Entropy, Correlation dimension, Detrended Fluctuation Analysis, Recurrence Plot. For statistical comparison, we adopted the Wilcoxon Signed Rank test and for development of a classifier we adopted the Linear Discriminant Analysis (LDA). Results: Almost all HRV features measuring heart rate complexity were significantly decreased in the stress session. LDA generated a simple classifier based on the two Poincaré Plot parameters and Approximate Entropy, which enables stress detection with a total classification accuracy, a sensitivity and a specificity rate of 90%, 86%, and 95% respectively. Conclusions: The results of the current study suggest that nonlinear HRV analysis using short term ECG recording could be effective in automatically detecting real-life stress condition, such as a university examination

    THE TECHNICAL MANAGEMENT OF HEALTH INFORMATION SYSTEMS

    Get PDF
    The technical management of ICT/Telemedicine Services is one Hospital Manager's crucial problem. The Biomedical Technologies Market has clearly shown that technical support to the user is one of the most critical issues that contribute to guarantee the quality of service in High-Tech applications. Therefore the ICT/Telemedicine Services, which belong to the high innovation area as well, require adequate competencies and human resources in order to provide users with a proper technical support. All these technologies require on the one hand a specialist who normally works remotely (II level support) and on the other hand an ordinary management activity (I level technical support) in order to avoid that medical staff stop their work in the operative env

    How should i treat concomitant post - endarterectomy carotid pseudoaneurysm and contralateral symptomatyc stenosis?

    Get PDF
    Background: A 74-year-old male patient complaining of crescendo TIAs, hypertension and hyperlipidaemia. Investigation: Duplex ultrasound scan MR angiography. Diagnosis: Pseudoaneurysm stemming from the ICA. Treatment: An open or endovascular procedure for the right pECCA repair, or a left CEA or CAS

    Endovascular treatment of spontaneous isolated abdominal aortic dissection

    Get PDF
    Isolated abdominal aortic dissection is a rare clinical disease representing only 1.3% of all dissections. There are a few case series reported in the literature. The causes of this pathology can be spontaneous, iatrogenic, or traumatic. Most patients are asymptomatic and symptoms are usually abdominal or back pain, while claudication and lower limb ischemia are rare. Surgical and endovascular treatment are two valid options with acceptable results. We herein describe nine cases of symptomatic spontaneous isolated abdominal aortic dissection, out of which four successfully were treated with an endovascular approach between July 2003 and July 2013. All patients were men, smokers, symptomatic (either abdominal or back pain or lower limb ischemia), with a history of high blood pressure, with a medical history negative for concomitant aneurysmatic dilatation or previous endovascular intervention. Diagnosis of isolated abdominal aortic dissection were established by contrast-enhanced computed tomography angiography (CTA) of the thoracic and abdominal aorta. All nine patients initially underwent medical treatment. In four symptomatic cases, non-responsive to medical therapy, bare-metal stents or stent grafts were successfully positioned. All patients completed a CTA follow-up of at least 12 months, during which they remained symptom-free. Endovascular management of this condition is associated with a high rate of technical success and a low mortality; therefore, it can be considered the treatment of choice when it is feasible

    Ferredoxin-ferredoxin NADP reductase interaction:catalytic differnces between the soluble and thylakoid-bound complex

    Get PDF
    2Ferredoxin-NADP reductase (FNR) and ferredoxin form a complex when the former is membrane-bound as they do when both components are in solution, with the same dissociation constant. The rate constant of NADP photoreduction, first order with respect to the complex, is more than 20-times higher when FNR is membrane-bound than when the enzyme is in solution. The Arrhenius activation energy is identical in both conditions. These observations are interpreted in terms of ‘entropic catalysis’ of NADP reduction by the thylakoid-bound FNR.openForti G.; Bracale M.Forti, G.; Bracale, Marcell

    Emergency endovascular management of the common femoral artery rupture due to radiotherapy for scrotal carcinoma

    Get PDF
    We describe the case of a 72-year-old man with massive hemorrhage and shock resulting from rupture of the left common femoral artery as a complication of radiotherapy in the groin for cancer of the scrotum. This complication is extremely rare, presents dramatically, and is usually fatal. The patient was successfully treated with a stent graft deployment in order to achieve immediate hemostasis maintaining blood flow to the leg. Open surgery is not ideal in those cases especially when there is extensive tumor involvement of the groin causing altered anatomy and increasing the risk of re-bleeding

    Laparoscopic treatment of abdominal unicentric castleman's disease: a case report and literature review.

    Get PDF
    BACKGROUND: Castleman's disease is a rare lymphoproliferative disorder of unknown etiology that most commonly presents as a mediastinal nodal mass. It is exceptionally uncommon for Castleman's disease to present in the mesentery and, only 53 cases have ever been described in the literature. Standard treatment for this lymphoproliferative disorder involving a single node is a complete "en bloc" surgical resection which has proven to be a curative approach in almost all cases without recurrence after 20 years of follow up. All 53 reported cases of mesenteric Castleman's disease, except one, were treated with laparotomy. CASE PRESENTATION: We report on a case of mesenteric Castleman's disease localized in the mesentery which is the second reported case if its kind and was treated by a laparoscopic-assisted procedure. Our female patient had an uneventful postoperative course and was discharged in the 5th post-operative day. No signs of recurrence were present as evidenced by physical examination and total body CT scan 24 months after the operation. We compare our case with the other reported cases in which Castleman's disease presented as an isolated mass in the abdomen. CONCLUSION: Although a rare disease, Unicentric Castleman's disease should always be considered when a solid asymptomatic abdominal mass is occasionally presented. The laparoscopic approach (LA) allows for the achievement of better results than open surgery, including a reduction in postoperative pain and length of hospital stay. In cases of masses of an uncertain nature, LA must be considered the last diagnostic tool and the first treatment one
    corecore