74 research outputs found

    The impact of conditional higher moments on risk management: The case of the tanker freight market

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    Tanker shipping provides the primary means of transportation for almost types of petroleum product traded globally. It is therefore essential to the energy supply chain to be able to correctly evaluate the structure and risk associated with freight rates in this market. This paper examines the concepts of conditional skewness and kurtosis in tanker freight rate. This is because, although the departure from normality of asset returns has been well documented, the relatively recent introduction of the concepts of conditional skewness and conditional kurtosis into the financial market literature, together with the unique shape of the supply curve in shipping markets, means that this has not been fully examined in the shipping literature. This is crucial given that a failure to take these structural characteristics into account could lead to market participants underestimating the probability of extreme and unfavourable events and therefore the consequent risk associated with market operations. Examining a sample of three types of tanker freight rate returns, we find that tanker freight rate returns exhibit conditional higher moments and that models that incorporate conditional skewness and kurtosis provide a more accurate value-at-risk measure and therefore a more accurate measure of the true risk faced by market participants

    A regime switching approach for hedging tanker shipping freight rates

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    Tanker shipping is the primary means for the transportation of petroleum and petroleum products around the world and thus plays a crucial role in the energy supply chain. However, the high volatility of tanker freight rates has been a major concern for market participants and led to the development of the tanker freight derivatives in the form of forward freight agreements (FFAs). The aim of this paper is to investigate the performance of these instruments in managing tanker freight rate risk. Using a data set for six major tanker routes covering the period between 2005 and 2013, we examine the effectiveness of alternative hedging methods, including a bivariate Markov Regime Switching GARCH model, in hedging tanker freight rates. The regime switching GARCH specification links the concept of equilibrium freight rate determination underlying different market conditions and the dynamics of the conditional second moments across high and low volatility regimes. Overall, we find evidence supporting the argument that the tanker freight market is characterized by different regimes. However, while the use of a regime switching model allows for a significant improvement in the performance of the hedge in-sample, out-of-sample results are mixed

    Frequency-dependent anti arrhythmic effects of crataegus monogyna on the extracellular field potential recordings in the rabbit atrioventricular node, an experimental model of AF

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    Introduction: Despite extensive studies that have been performed on the effects of Crataegus monogyna in cardiovascular diseases, only few investigations have addressed the antiarrhythmic properties of this plant. Aims of the present study were: 1) To determine the protective role of methanolic extract of C. monogyna on the rate-dependent model and the concealed conduction of the AV node. 2) To explore the role of Na+-K+ ATPase in the protective role of C. monogyna Methods: Male New Zealand rabbits (1.5-2kg) were used in all experiments. Stimulation protocols were used to measure basic and rate-dependent AV nodal properties (recovery, atrial fibrilation and zone of concealment) in two groups (N=14). In the first group, all the stimulation protocols were performed before and after the administration of different concentrations of C. monogyna extract (n=7), while in the second group (n=7), all stimulation protocols were carried out in the presence of ouabaine (0.05 μM) and the plant extract. Results: Basic and rate-dependent properties of the AV node were inhibited after the addition of the extract of C. monogyna to Kerebs Henselite solution. At the maximum concentration of C. monogyna (30 mg/l), WBCL cycle length was significantly increased from 156.5±3.4 to 173±5.8 ms and the nodal functional refractory period was prolonged from 164.4±4.1 to 182.7±3.8 ms (P<0.05). Significant decreases of ventricular rhythm were recorded in both selective concentrations of the plant extract. The depressant electrophysiological effect of C. monogyna on the AV node was not abolished by ouabaine, a selective inhibitor of Na+-K+ ATPase enzyme. Conclusion: The results showed a potential anti-arrhythmic and protective effect for C. monogyna. The effect of the plant extract in increasing nodal refractory period and widening of the concealment zone might be the major mechanisms involved. The protective role of C. monogyna was not related to the Na+-K+ ATPase activity

    Atherosclerosis in patients with endometriosis

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    Endometriosis refers to endometrial tissue implantation including stromal and epithelial tissue outside the uterus. It is an often painful disorder that involves the ovaries and fallopian tubes. The association between endometriosis and atherosclerosis is interesting. The present study was conducted to assess the Doppler findings of the carotid artery in patients with and without endometriosis. In this study that included 30 patients with endometriosis and 30 control subjects, all patients underwent carotid ultrasonography, and the measurement of intima-media thickness (IMT) was done in the distal common carotid artery, proximal to the origin of the carotid bulb, and finally, we compare the IMT in two groups. This study revealed that there are no differences in the IMT between patients with and without Endometriosis. © Copyright A.H. Habibi, et al., 2019

    Pantothenate kinase-associated neurodegeneration: Clinical aspects, diangnosis and treatments

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    Pantothenate Kinase-Associated, Neurodegeneration (PKAN) is an autosomal, recessive disorder characterized by a, mutation in the PANK2 gene. The clinical, presentation may range from only speech, disorder to severe generalized dystonia, spasticity, Visual loss, dysphagia and, dementia. The hallmark of this disease is, eyes of the tiger signs in the medial aspect, of bilateral globus pallidus on T2-weighted, MRI that is a hyperintense lesion surrounded, by hypointensity. Common treatments, for PKAN disease include anticholinergics, botulinum toxin, Oral and Intrathecal, baclofen, Iron chelation drugs and surgical, procedures such as ablative pallidotomy or, thalamotomy, Deep brain stimulation., There are many controversies about the, pathogenesis and treatment of this disease, and in recent years interesting studies have, been done on PKAN disease and other similar, diseases. This review summarizes the, clinical presentation, etiology, imaging, modalities and treatment. © S. Razmeh et al

    Pantothenate kinase-associated neurodegeneration: Clinical aspects, diangnosis and treatments

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    Pantothenate Kinase-Associated, Neurodegeneration (PKAN) is an autosomal, recessive disorder characterized by a, mutation in the PANK2 gene. The clinical, presentation may range from only speech, disorder to severe generalized dystonia, spasticity, Visual loss, dysphagia and, dementia. The hallmark of this disease is, eyes of the tiger signs in the medial aspect, of bilateral globus pallidus on T2-weighted, MRI that is a hyperintense lesion surrounded, by hypointensity. Common treatments, for PKAN disease include anticholinergics, botulinum toxin, Oral and Intrathecal, baclofen, Iron chelation drugs and surgical, procedures such as ablative pallidotomy or, thalamotomy, Deep brain stimulation., There are many controversies about the, pathogenesis and treatment of this disease, and in recent years interesting studies have, been done on PKAN disease and other similar, diseases. This review summarizes the, clinical presentation, etiology, imaging, modalities and treatment. © S. Razmeh et al

    Induction and aggravation of atrioventricular valve regurgitation in the course of chronic right ventricular apical pacing

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    Aims Valvular regurgitation, especially on the right side of the heart, is a common finding even in patients without endocardial pacing leads. The severity of valvular regurgitation can change after permanent pacemaker (PPM) implantation. Ventricular pacing has been shown to cause ventricular dysfunction. The purpose of this study was to evaluate the mid-term effects of right ventricular (RV) apical pacing on atrioventricular (AV) valvular regurgitation in patients with a normal left ventricular function before PPM implantation. Methods and results Patients who required dual-chamber pacemakers due to a high-degree AV block were enrolled in the study. Initial echocardiography was performed before PPM implantation and re-evaluation by echocardiography was performed every 24 months thereafter. A total of 125 patients (61 male; mean age: 66.57 ± 6.45 years) were included in the study, and 115 pacemaker-dependent patients were followed up (mean ± SD; 4.08 ± 0.8 years). Echocardiography demonstrated mild tricuspid regurgitation (TR) and mitral regurgitation (MR) in 70 (60.1) and 34 (29.6) patients before PPM implantation, respectively. Moderate TR and MR were detected in 10 (8.7) and 1 (0.9) patients, respectively. Thirty-six (31.6) patients showed moderate-to-severe TR at long-term follow-up, compared with the 10 (8.7) patients, who had the same degree of TR before RV apical pacing (P< 0.001). Mild and moderate MR were detected in 54 (47) and 8 (7) patients after PPM implantation on the last echocardiography(P< 0.001). Baseline systolic pulmonary artery pressure (PAP) was 29.24 ± 8.45 mmHg, which increased to 36 ± 11 mmHg on the last echocardiography (P< 0.001). Conclusion Considering the haemodynamic effects at mid-term follow-up, left ventricular dysfunction is rare in patients with RV apical pacing and normal baseline left ventricular function. Right ventricular apical pacing is associated with a significant increase in the prevalence and severity of TR and MR. © The Author 2011

    A novel homozygous variation in the PANK2 gene in two Persian siblings with atypical pantothenate kinase associated neurodegeneration

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    Pantothenate Kinase-associated Neurodegeneration (PKAN) is an autosomal recessive disorder that is caused by variation in pantothenate kinase-2 gene (PANK2) gene on chromosome 20. The common presentation of this disease includes progressive dystonia, Parkinsonism, retinopathy, cognitive impairment, and spasticity. The typical magnetic resonance imaging finding is eye of the tiger sign in globus pallidus and not pathogenic and not found in all patients. In the present study, we describe two siblings who have a novel variation of the PANK2 gene. These patients with the same genotype, have different ages at the onset of disease and also the various severity of the disease. The description of these cases helps to understand this disease, its symptoms, pathogenesis, and its treatment. © A.H. Habibi et al., 2019

    Improvement of black tilapia (Oreochromis niloticus) diets with replacement of low-cost, native materials

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    Fish meal production has been fixed in the world because of a limitation in fish stocks. On the other hand, demand of fish meal is growing daily and consequent the cost, too. Therefore, attention to the other protein sources is nessesary. Some plant protein sources, especially oilseeds, have valuable potentials for replacing fish meal because of relative high production in the world and Iran and low cost. According to existing information and availability, cottonseed meal and canola meal were selected as oilseeds; and Azolla was considered whether to be controlled in north provinces of Iran as weed. Growth indices (WG and SGR), food (FCR) and protein efficiency (PER and PCE) of fingerling Nile tilapia Oreochromis niloticus were evaluated in 3 synchronous examinations with 12 treatments and 36 replications. Groups of control, canola meal (at rates of 25, 50, 75 and 100%), cottonseed meal (at rates of 15, 25, 35 and 45%), as the replacements of expensive protein sources (fish meal and soybean meal), and azolla (at rates of 13, 21 and 29% of diet) were studied. Growth indices, total food intake and protein intake of control group were higher than all diets contained plant protein sources. They decreased with plant protein increasing in every grous, separagely (p0.05) between control and canola meal (at rates of 25 and 50%), cottonseed meal (at rates of 15, 25 and 35%) and azolla (at rates of 13 and 21%). All plant protein ingredients were unpalatable, and consequent total food intake, protein consumption and growth decreased. It will be expected that Canola meal and cottonseed meal replace expensive protein sources at the rates of 50 and 35% respectively, and azolla use at the rate of 21% in diets If the problem in palatability solves

    Intentional injuries in the Eastern Mediterranean Region, 1990�2015: findings from the Global Burden of Disease 2015 study

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    Objectives: We used GBD 2015 findings to measure the burden of intentional injuries in the Eastern Mediterranean Region (EMR) between 1990 and 2015. Methods: The Global Burden of Disease (GBD) study defines intentional injuries as a combination of self-harm (including suicide), interpersonal violence, collective violence (war), and legal intervention. We estimated number of deaths, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life years (DALYs) for each type of intentional injuries. Results: In 2015, 28,695 individuals (95 UI: 25,474�37,832) died from self-harm, 35,626 (95 UI: 20,947�41,857) from interpersonal violence, and 143,858 (95 UI: 63,554�223,092) from collective violence and legal interventions. In 2015, collective violence and legal intervention was the fifth-leading cause of DALYs in the EMR and the leading cause in Syria, Yemen, Iraq, Afghanistan, and Libya; they account for 49.7 of total DALYs in Syria. Conclusions: Our findings call for increased efforts to stabilize the region and assist in rebuilding the health systems, as well as increasing transparency and employing preventive strategies to reduce self-harm and interpersonal injuries. © 2017, The Author(s)
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