Analysis and forecast of the capesize bulk carriers shipping market using Artificial Neural Networks

Thesis (S.M. in Ocean Systems Management)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (leaves 188-189).Investing in the bulk carrier market constitutes a rather risky investment due to the volatility of the bulk carrier freight rates. In this study it is attempted to uncover the benefits of using Artificial Neural Networks (ANNs) in forecasting the Capesize Ore Voyage Rates from Tubarao to Rotterdam with a 145,000 dwt Bulk carrier. Initially, market analysis allows the assessment of the relation of some parameters of the dry bulk market with the evolution of freight rates. Subsequently, ANNs with an appropriate architecture are constructed and sufficient data, in terms of quantity and quality, are collected and organized so as to establish both the training and the testing data sets. The use of ANNs along with genetic algorithms allows the prediction of bulk freight rates with considerable accuracy for as long as eighteen months ahead and this is quantified by calculating the relative and absolute errors. It is concluded that ANNs offer a promising approach to forecasting the bulk market when coupled with efficient market modeling.by Athanasios V. Voudris.S.M.in Ocean Systems Managemen

Angiotensin-converting enzyme insertion/deletion polymorphism does not influence the restenosis rate after coronary stent implantation

Background. Experimental studies have shown an activation of the angiotensin-converting enzyme (ACE) system as a response to endothelial injury. Recent publications have elucidated the hypothesis that the ACE gene polymorphism may influence the level of late luminal loss after coronary stent implantation. It is still unclear whether the polymorphism of the angiotensin gene is a major predictor of the extent of neointimal hyperplasia. In this multicenter study, we therefore tested the relationship between the ACE gene polymorphism and the restenosis rate after coronary stent implantation. Methods: As a substudy of the optimization with intracoronary, ultrasound (ICUS) to reduce stent restenosis (OPTICUS) study, we analyzed ACE serum levels and the ACE gene polymorphism in 154 patients at 9 different centers. All patients underwent elective coronary stent implantation in a stenosis of a major coronary vessel. Balloon inflations were repeated until a satisfactory result was achieved in on-line quantitative coronary angiography or ICUS fulfilling the OPTICUS study criteria. After follow-up of 6 months, all patients underwent reangiography tinder identical projections as the baseline procedure. A blinded quantitative analysis of the initial procedure as well as the follow-up examinations were performed by an independent core laboratory. ACE gene polymorphism and ACE serum activity were measured at the 6-month follow-up in a double-blinded setting. Results: With respect to the ACE gene polymorphism, there were three subgroups: DID genotype (48 patients), ID (83 patients) and 11 (23 patients). The subgroups did not differ in regard to age, gender, extent of coronary artery disease, stenosis length, initial degree of stenosis or degree of stenosis after stent implantation. In all, 39 patients (25.3%) had significant restenosis: 12 DD patients (25.0%), 18 ID patients (21.7%) and 9 II patients (39.1%) (odds ratio 2.164, 95% confidence interval 0.853-5.493). We obtained the following results for ACE serum levels: 0.53 mumol/l/s in the DD subgroup, 0.29 mumol/l/s in the ID

Alkaline phosphatase and its isoenzyme activity for the evaluation of bone metabolism in children receiving anticonvulsant monotherapy

AbstractThis study aimed to investigate whether carbamazepine, sodium valproate or phenobarbital as monotherapy in ambulatory epileptic children with adequate sun exposure have some effect on their bone metabolism based on the determination of total serum alkaline phosphatase (AP) levels and its bone isoenzyme activity. Blood samples were obtained from 118 epileptic children (37 on carbamazepine, 47 on sodium valproate and 34 on phenobarbital) and from corresponding healthy controls matched for age, gender and anthropometric parameters. AP and its liver, bone and intestinal isoenzyme levels, other common biochemical markers of bone and liver metabolism and drug levels were measured in the study participants. Patients on carbamazepine or phenobarbital had significantly elevated AP levels accompanied by increased bone and liver isoenzyme activity compared to controls. An increase of bone AP isoenzyme values, correlated with the duration of treatment ( r= 0.49, P= 0.002), was found in children on sodium valproate without, however, a concomitant significant elevation of total AP values. We conclude that children who receive antiepileptic drugs as monotherapy, even when residing in a Mediterranean country with adequate sunlight, may have their bone metabolism affected as indicated by the elevated levels of bone AP isoenzyme. This isoenzyme, but not total AP values, could therefore be used as a marker for the selection of patients who would be benefited by a thorough evaluation of their bone metabolism profile

A case of acute necrotizing encephalopathy associated with parainfluenza virus infection

Acute necrotizing encephalopathy (ANE) may be suspected when a young child presents with abrupt onset of altered mental status, seizures, or both. Definitive clinical diagnosis is based on magnetic resonance imaging (MRI) results. ANE is associated with influenza virus infections. Preliminary data suggests that up to 25% of ANE patients die, and up to 25% of ANE survivors develop substantial neurologic sequelae. Here, we describe a case of a comatose 22-month-old girl who was admitted to our hospital because of febrile illness and seizures. On day 13 of her illness, she died from ANE associated with infection from parainfluenza virus. Brain MRI results indicated diffuse bilateral symmetric signal changes in both basal ganglia, thalami, periventricular white matter, pons, and cerebral white matter, as well as generalized swelling of the brain

Left Ventricular Mass One Year After Radiofrequency Ablation for Atrial Fibrillation

Myxomas are the most common benign tumors of the heart. The exact etiology of myxomas is unknown and most cases are sporadic. It is well known though that myxomas can develop after cardiac trauma, and that radiofrequency ablation (RFA) for paroxysmal atrial fibrillation (PAF) increases the risk of thrombus or endocarditis in the atrium. The association of RFA and the formation of myxomas is not known. We report a case of a left ventricular myxoma in a patient after RFA

Influence of age on the clinical outcomes of coronary revascularisation for the treatment of patients with multivessel de novo coronary artery lesions: sirolimus-eluting stent vs. coronary artery bypass surgery and bare metal stent, insight from the multicentre randomised Arterial Revascularisation Therapy Study Part I (ARTS-I) and Part II (ARTS-II)

peer reviewedAims: We sought to evaluate the prognostic impact of age on the procedural results and subsequent clinical outcomes in patients with multivessel disease (MVD) treated either by coronary artery bypass surgery (CABG) or by percutaneous coronary intervention (PCI) with or without drug eluting stents, based on data of the Arterial Revascularisation Therapies Study (ARTS) part I and part II. The potential influence of age in determining the most appropriate revascularisation strategy for patients with MVD is largely unknown. Methods and results: Three year clinical outcome of ARTS I patients randomised to PCI with bare metal stent (BMS) (n= 600) or CABG (n= 605), and matched patients treated by PCI with sirolimus-eluting stents (SES) in ARTS II (n= 607) were reviewed according to four age quartiles. Endpoints were measured in terms of major adverse cardiac and cerebrovascular events MACCE) during hospital stay and up to three years. The frequency of female, diabetes, hypertension, peripheral vascular disease, pulmonary disease, as well as lesion complexity increased with age. At three years, MACCE free survival was comparable between patients treated by CABG or SES PCI, regardless of age quartile. The incidence of MACCE was higher among ARTS I BMS treated patients in all but the second age quartile. This was primarily related to a higher need for repeat revascularisation among BMS treated patients. However, age, which emerged as a strong independent predictor of MACCE following CABG (p<0.005), was not predictive of adverse events following PCI. Conversely, diabetes was the strongest independent predictor of MACCE among PCI treated patients (p<0.02), but didn’t affect three-year outcomes following CABG. Conclusions: Age seems to influence the CABG outcome in-hospital but not PCI. PCI-SES could offer lower immediate risk in patients with MVD and comparable long-term outcome as CABG especially in older patients. The worst outcome of PCI-BMS group is primarily related to the need for repeat revascularisation. Diabetes is the most important predictor of MACCE following PCI

Randomized comparison of primary stenting and provisional balloon angioplasty guided by flow velocity measurement.

BACKGROUND: Coronary stenting improves outcomes compared with balloon angioplasty, but it is costly and may have other disadvantages. Limiting stent use to patients with a suboptimal result after angioplasty (provisional angioplasty) may be as effective and less expensive. METHODS AND RESULTS: To analyze the cost-effectiveness of provisional angioplasty, patients scheduled for single-vessel angioplasty were first randomized to receive primary stenting (97 patients) or balloon angioplasty guided by Doppler flow velocity and angiography (523 patients). Patients in the latter group were further randomized after optimization to either additional stenting or termination of the procedure to further investigate what is "optimal." An optimal result was defined as a flow reserve >2.5 and a diameter stenosis <36%. Bailout stenting was needed in 129 patients (25%) who were randomized to balloon angioplasty, and an optimal result was obtained in 184 of the 523 patients (35%). There was no significant difference in event-free survival at 1 year between primary stenting (86.6%) and provisional angioplasty (85.6%). Costs after 1 year were significantly higher for provisional angioplasty (EUR 6573 versus EUR 5885; P:=0.014). Results after the second randomization showed that stenting was also more effective after optimal balloon angioplasty (1-year event free survival, 93.5% versus 84.1%; P:=0. 066). CONCLUSIONS: After 1 year of follow-up, provisional angioplasty was more expensive and without clinical benefit. The beneficial value of stenting is not limited to patients with a suboptimal result after balloon angioplasty

Clinical Presentation and Angiographic Characteristics of Saphenous Vein Graft Failure After Stenting Insights From the SOS (Stenting Of Saphenous Vein Grafts) Trial

ObjectivesWe sought to compare the clinical presentation and angiographic patterns of saphenous vein graft (SVG) failure after stenting with a paclitaxel-eluting stent (PES) versus a similar bare-metal stent (BMS).BackgroundThe mode of SVG failure after stenting has been poorly characterized.MethodsThe SOS (Stenting Of Saphenous Vein Grafts) trial enrolled 80 patients with 112 lesions in 88 SVGs who were randomized to a BMS or PES. Angiographic follow-up at 12 months was available in 83% of the patients.ResultsBinary angiographic restenosis occurred in 51% (24 of 47) of BMS-treated lesions versus 9% (4 of 43) of PES-treated lesions (p < 0.0001). Graft occlusion occurred in 9 of the 21 SVGs (43%) that failed in the BMS group and in 2 of 4 SVGs (50%) that failed in the PES group. SVG failure after stenting presented as an acute coronary syndrome in 10 of the 24 patients (42%) (7 of those 10 patients presented with non–ST-segment elevation acute myocardial infarction), stable angina in 9 (37%) patients, and without symptoms in 5 (21%) patients. Of the 19 patients (with 20 grafts) who developed symptomatic graft failure, repeat SVG revascularization was successfully performed in all 13 (100%) subtotally obstructed SVGs but was attempted (and successful) in only 1 of 7 (14%) occluded SVGs. Revascularization of a native coronary artery was performed in an additional 4 of 7 (57%) symptomatic patients with an occluded SVG.ConclusionsSVG failure after stenting often presents as acute myocardial infarction and with SVG occlusion. Compared with BMS, PES reduce SVG failure