441 research outputs found
An agglomerative hierarchical clustering method for text in Albanian
No full textNowadays, big data is available in many areas of science, so the need to summarize data sets into groups and extract information is important. Using the cluster analysis technique, we can explore such data based on their similarity. The degree of similarity in the data is quantitatively represented by distance functions.
In this paper, using Ward’s method of cosine distance in a database with 100 Albanian texts into 16 different clusters based on the frequency of words, with 87 percent of texts well classified by author
Does off-pump coronary revascularization reduce the release of the cerebral markers, S-100beta and NSE?
No full textAbstract
OBJECTIVES:
The aims of this study were to (1) compare the release of S-100 beta and NSE in off-pump coronary artery bypass grafting (CABG) versus on-pump surgery; (2) investigate whether the S-100 beta and NSE serum concentrations correlate with cardiopulmonary bypass (CPB) duration.
MATERIALS AND METHODS:
Between October 2002 and May 2004, 42 patients undergoing first time CABG surgery were enrolled in the study. The exclusion criteria were: LVEF70 years, previous myocardial infarction, REDO surgery, the presence of valvular heart disease and/or cerebrovascular disease, abnormal preoperative carotid vessels angiography, coronary artery disease involving the distal circumflex artery, renal dysfunction, coagulopathy. The patients were randomly assigned either to undergo on-pump CABG surgery [group I, n=24 patients] or off-pump CABG [group II, n=18 patients]. Blood was not re-transfused from the cardiotomy suction. All patients presenting haemolysis were excluded from the study.
RESULTS:
The preoperative S-100beta was 0.13+/-0.08 (microg/l) and NSE 7+/-1.5 (microg/l) in group I and 0.12+/-0.1 (microg/l) and 6.9+/-2.7 (microg/l), respectively in group II. Six hours after the surgery, S-100beta in patients of group I reached a maximum level of 1.38+/-0.4 (microg/l) and NSE of 17.7+/-6.5 (microg/l) compared to 0.5+/-0.11 (microg/l) [S-100B] and NSE 8.6+/-4.2 (microg/l) in group II (p=0.001). Three (12%) patients in group I and none (0%) in group II suffered postoperative delirium, p=0.247. No strokes occurred linear regression analysis revealed a strong correlation between cardiopulmonary bypass duration and S-100beta and NSE peak levels, p<0.0021 (r(2)=0.36) and p<0.0001 (r=0.81), respectively.
CONCLUSION:
Coronary artery bypass surgery with CPB causes a significantly greater increase in NSE and S-100beta serum levels than off-pump surgery and correlates with CPB duration
Assessing the impacts of home-grown school feeding programmes
No full textGlobally, millions of children receive meals at school through home-grown school
feeding (HGSF) programmes that link school feeding programmes with local
smallholder farmers. Countries such as Brazil, Ethiopia, Ghana, Kenya and Nigeria
have undertaken HGSF initiatives. However, with a few exceptions, there is a
dearth of empirical evidence on the effectiveness and economic sustainability of
such programmes. This evidence gap is due to the innate difficulties of applying
standard impact evaluation approaches to complex programmes that combines
two interventions, each of which has specific target populations. This chapter aims
to support practitioners by providing methodological guidelines for conducting
rigorous impact assessments of HGSF programmes. It presents an overview of the
main technical issues to be addressed, depending on the characteristics of the
context and of the intervention itself. The chapter focuses on the methodological
challenges related to the estimation of the effects of HGSF interventions on farmers
Dynamic Modeling and Validation of an Industrial Vacuum Thermodeasphalting Column for the Regeneration of Used Oil
No full textDynamic process simulation is a valuable strategy to enhance the reliability of transient operations in chemical plants. Deviations from normal operating conditions may be necessary to perform corrective actions against any external disturbance that may alter the performance of some process units. Moreover, some standard plant operations are intrinsically transient in nature, such as start-up and shut-down procedures. Used oil waste re-refining industry is beginning to explore this strategy, which could lead to successful outcomes, similarly to what has been observed in the crude oil refining industry. This work proposes a modeling approach for the dynamic simulation of a thermodeasphalting column for the regeneration of used oil, currently operative in the Itelyum Regeneration re-refining facility in Pieve Fissiraga. The modeling strategy introduces a discretization of the column sections, a reasoned choice of appropriate thermodynamic methods, and the calculation of the main equilibrium and transport parameters necessary to solve mass, energy, and momentum balances on the column sections. The model is validated with experimental data, showing good agreement regarding both manipulated and controlled variables, thus becoming a valuable tool for the aprioristic evaluation of critical transient operations such as start-up, shut-down, and accidents simulation
Accessory mitral valve tissue causing left ventricular outflow tract obstruction: case reports and literature review.
No full textAccessory mitral valve (AMV) tissue is a rare congenital malformation causing left ventricular outflow tract obstruction (LVOTO). We present three patients with AMV tissue undergoing surgery. A 60-year old man presented with an AMV leaflet, mild LVOTO and coronary artery disease and underwent accessory leaflet excision and coronary revascularization. A 24-year old man presented with an AMV leaflet, LVOTO and interatrial septal defect and underwent defect closure and accessory leaflet resection. An 8-month-old girl underwent interventricular septal closure and AMV leaflet resection but died on postoperative day 5 from progressive heart failure. Another 87 cases with AMV tissue were identified in the literature The anomaly was classified as: Type I (fixed: A = nodular, B = Membranous), and type II (mobile: A = pedunculated, B = leaflet like). Type IIB was further subdivided as rudimentary chordae and developed chordae. Patients with AMV tissue causing LVOTO may undergo mass removal with acceptable postoperative outcome. Prophylactic removal of AMV tissue should not be attempted in patients with no or mild LVOTO and no other associated heart defects. These patients should be followed and observed periodically by Doppler echocardiography to identify any progression in LVOTO
Urgent/emergent surgical revascularization in unstable angina: influence of different type of conduits
No full textAbstract
AIM:
In patients with unstable angina (UA) undergoing nonelective myocardial revascularization we compare the outcomes of skeletonized bilateral internal mammary arteries (BIMA) vs left internal mammary artery (LIMA) and saphenous vein grafts (SVGs) vs SVGs only.
METHODS:
Between January 1997 and December 2003, 758 patients: 612 (80.7%) males, mean age 62+/-12 years, underwent nonelective coronary artery bypass grafting (CABG) for unstable angina; 205 (27%) were operated emergently and 553 (73%) urgently. BIMA were employed in 320 (42%) patients (Group B) , isolated LIMA and/or SVGs in 332 (44%) patients (Group M) and only SVGs in 106 (14%) (Group S).
RESULTS:
In-hospital mortality (B=5.9%, M=4.5% and S=7.5%), and perioperative myocardial infarction (B=2.2%; M=1.9%, S=3.7%) were similar between the 3 groups (P=NS). Actuarial survival at 1, 3 and 7 years was 98.7%, 97.5% and 96.2% in group B, 99.3%, 94.8% and 89.4% in group M (P65 years (P= 0.02), left ventricular ejection fraction (LVEF) 1 ischemic irreversible area (P= 0.03) as independent predictors for late deaths, while the use of the LIMA (P= 0.006) and both mammary arteries (P= 0.001) decreased the risk of late deaths.
CONCLUSIONS:
The use of BIMA in nonelective CABG for UA is safe and effective. There is a trend, however, toward a survival benefit with improved freedom from late cardiac events (recurrence of angina, freedom from reoperation and infarction)
Repair of congenital malformations of the mitral valve: Early and midterm results
No full textBackground. The aims of this study were to determine early and midterm survival and freedom from reoperation, and to identify the predictors for poor postoperative outcome in children undergoing mitral valve (MV) repair owing to congenital malformations of the mitral valve. Methods. Between January 1990 and February 2001, 94 consecutive children with congenital MV disease underwent valve repair. The mean age was 5.2 +/- 3.3 years (range 20 days to 15 years). Twenty-five (26.6%) children were less than 1 year old. Isolated MV disease was found in 21 (22.4%) patients. MV stenosis was the predominant lesion in 21 (22.4%) patients with a mean left atrial to left ventricle diastolic peak gradient of 24.5 +/- 9.2 mm Hg. MV regurgitation was the predominant pathophysiology in 73 (77.6%) patients with a mean regurgitation grade of 3.3 +/- 0.7. Results. The hospital mortality was 8.5% (8 of 94). Three patients required permanent pacemaker implantation owing to complete atrioventricular block. Two patients underwent mediastinal exploration for significant bleeding. Postoperatively the echocardiography color Doppler study demonstrated a significantly lower mean end diastolic left atrium to left ventricle gradient 8.7 +/- 2.2 mm Hg (p < 0.001) in patients with MV stenosis and a mean regurgitation grade of 0.9 +/- 0.6 (p < 0.001) in patients with MV regurgitation. Actuarial survival and actuarial reoperation-free survival were 89.2% and 76.3%, respectively. Multivariate analysis demonstrated that age less than 1 year (p = 0.035), hammock MV (p = 0.0093), cardiothoracic ratio greater than 0.6 (p < 0.0001), and associated cardiac anomalies (p = 0.003) were strong predictors for poor overall freedom from reoperation and midterm survival. Conclusions. Mitral valve repair for congenital mitral valve disease yields acceptable early and midterm mortality and reoperation rates. Strong predictors for poor overall freedom from reoperation and midterm survival were age less than 1 year, hammock MV, cardiothoracic ratio greater than 0.6, and associated cardiac anomalies. (C) 2002 by The Society of Thoracic Surgeons
Reconstructive surgery for congenitally malformed mitral valve.
No full textThe study aims were to evaluate early and mid-term survival and freedom from reoperation in patients with isolated mitral valve (MV) congenital malformation (MVCM) or in association with other cardiac defects, and to identify predictors for poor early and late outcome. Between January 1990 and February 2001, 58 children with MVCM underwent MV-conserving surgery; patients were allocated to group I (n = 21) with isolated MVCM, and group II (n = 37) with MVCM and associated congenital heart defects (ACHD). MV stenosis was identified in 10 (48%) group I patients, and 11 (30%) group II patients (p = NS); MV insufficiency was present in 11 (52%) patients in group I, and in 26 (70%) of group II (p = NS). The most frequently found MVCM were annular dilatation (n = 13) cases and elongated chordae (n = 14). Hammock MV was found in nine patients (15%). Six (10%) hospital deaths occurred. Mortality was 5% (n = 1) in group I, and 13% (n = 5) in group II (p = 0.4). Mean repair techniques per patient was 2.05+/-0.4 and 2.3+/-0.3 in groups I and II respectively (p = 0.009). Mechanical ventilation time was 2.1+/-1 and 2.8+/-0.7 days in groups I and II (p = 0.003). The incidence of postoperative mitral regurgitation grade > or =1 was significantly higher in group II (p = 0.008). At five-year follow up, actuarial survival was 91.5% in group I and 86% in group II (p = 0.037). Actuarial reoperation-free survival was 85% in group I and 73% in group II (p = 0.01). Multivariate analysis showed age >12 months (p = 0.033), hammock MV (p = 0.0088) and ACHD (p = 0.0048) were strong predictors for poor event-free survival. MV repair for MVCM provides acceptable early and mid-term outcome in terms of mortality and freedom from reoperation. ACHD significantly reduce early and late postoperative survival and freedom from reoperation
Converting end-of-life plastic waste into methanol: the gasiforming process as new, efficient and circular pathway
No full textThe mixed plastic waste problem is becoming an important issue in scientific and technological communities in light of the environmental pollution caused by its poorly management. In this paper a new and efficient thermo-catalytic pathway to convert plastic waste into methanol is presented in its key features and global yields. The process has been mainly developed in silico using Aspen HYSYS V10 with support from experimental data where simulation could not provide reliable information such as the gasification step. Consolidated kinetic models are used both for the reforming and methanol synthesis steps, while the pre-reforming reactor is simulated at the thermodynamic equilibrium. The temperature, pressure, and mass flow balances of the system are reported alongside some of the most important key performance indicators for reforming (methane slip) and methanol synthesis (SN ratio)
Impact of SOA-Based Add-Drop Switch Nodes on High-Capacity Multicarrier Transmission for Metro-Access Networks
No full textInternet-generated traffic growth is forcing the development of new low-cost solutions in metropolitan area networks (MANs), in particular in the transceiver and network node architectures. Semiconductor optical amplifier (SOA)-based wavelength blockers can be used as fundamental building blocks to add and drop optical channels in the node architecture of several network hierarchical levels. Even if its employment is advantageous in terms of costs and amplification bandwidth, the SOA can operate in a nonlinear regime. This work analyzes the impact of SOA-based node crossing on high-capacity discrete multitone (DMT) signals. In order to properly evaluate the interplay between optical channels and SOA self-gain modulation, both external and direct modulations are considered. Dual-sideband (DSB) and single-sideband (SSB) DMT variants are taken into account, showing no significant difference in the impact of SOA crossing for external modulation of a DFB laser. On the other hand, an important effect of subcarrier suppression arises on DSB DMT direct modulation of a vertical cavity surface emitting laser (VCSEL), less consistent for SSB DMT direct modulation. The analysis allowed to properly choose the bias current for the SOA employed in an experimental setup used to evaluate the transmission performance in a MAN scenario including add-drop lossless switch nodes. The experimental results demonstrate that a target capacity of more than 50 Gb/s per channel can be achieved in a 116-km MAN network composed of an SOA-based metro-access node and two metro-core aggregators, considering the transmission of three 25-GHzspaced DMT channels
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