Forecasting crude oil and refined products volatilities and correlations: New evidence from fractionally integrated multivariate GARCH models

The relationship between the prices of crude oil and its refined products is at the heart of the oil industry. Crude oil and refined products volatilities and correlations have been mod- elled extensively using short-memory multivariate GARCH models. This paper investigates the potential benefits from using fractionally integrated multivariate GARCH models from a fore- casting and a risk management perspective. Several models for the spot returns on three major oil-related markets are compared. In-sample results show significant evidence of long-memory decay and leverage effects in volatilities and of time-varying autocorrelations. The forecasting performance of the models is assessed by means of three approaches: the Superior Predictive Ability test, the Model Confidence Set and the Value-at-Risk. The results indicate that the multivariate models incorporating long-memory outperform the short-memory benchmarks in forecasting the conditional covariance matrix and associated risk magnitudes. The paper makes an innovative contribution to the analysis of the relationship between crude oil and its refined products providing refiners, physical oil traders, non-commercial oil traders and other energy markets agents with significant insights for hedging and risk management operations

Dental pulp stem cells bioadhesivity: evaluation on mineral-trioxide-aggregate.

Stem cells are undifferentiated cells that have the capacity to self-renew. They have been discovered in many adult tissues, including teeth. Dental Pulp Mesenchymal Stem Cells (DP-MSCs) are involved in dental repair by activation of growth factors, released after caries and have the ability to regenerate a dentin-pulp-like complex. The molecular/cellular research gives the possibility to grow new tissues and biological structures for clinical applications, providing cells for therapies including cell transplantation and tissue engineering. In this study DP-MSCs were derived from dental pulp of 10 donors. To evaluate material toxicity, after in vitro isolation, the cells were seeded on mineral trioxide aggregate (MTA). Initial light microscopy investigation of cells revealed no signs of cell death due to toxicity or infection, on the contrary the scaffolds supplied an excellent support for cell structures, the cells proliferated and adhered to substrate. Similar observation was seen in scanning electron microscopy, in particular the cells had proliferated and spread, covering a considerable part of the surface of the biomaterials investigated, with an elaborate form of attachment, in fact, the cells formed a continuous layer on the upper surface of the MTA. In conclusion, the aim of this study is to demonstrate that DP-MSCs combined with MTA could be a potential source for regenerative medicine, encouraging further study to evaluate the new-dentin formation

Autosomal-dominant myopia associated to a novel P4HA2 missense variant and defective collagen hydroxylation

We recently described a complex multisystem syndrome in which mild-moderate myopia segregated as an independent trait. A plethora of genes has been related to sporadic and familial myopia. More recently, in Chinese patients severe myopia (MYP25, OMIM:617238) has been linked to mutations in P4HA2 gene. Seven family members complaining of reduced distance vision especially at dusk underwent complete ophthalmological examination. Whole-exome sequencing was performed to identify the gene responsible for myopia in the pedigree. Moderate myopia was diagnosed in the family which was associated to the novel missense variant c.1147A > G p.(Lys383Glu) in the prolyl 4-hydroxylase,alpha-polypeptide 2 (P4HA2) gene, which catalyzes the formation of 4-hydroxyproline residues in the collagen strands. In vitro studies demonstrated P4HA2 mRNA and protein reduced expression level as well as decreased collagen hydroxylation and deposition in mutated fibroblast primary cultures compared to healthy cell lines. This study suggests that P4HA2 mutations may lead to myopic axial elongation of eyeball as a consequence of quantitative and structural alterations of collagen. This is the first confirmatory study which associates a novel dominant missense variant in P4HA2 with myopia in Caucasian patients. Further studies in larger cohorts are advisable to fully clarify genotype-phenotype correlations.We recently described a complex multisystem syndrome in which mild-moderate myopia segregated as an independent trait. A plethora of genes has been related to sporadic and familial myopia. More recently, in Chinese patients severe myopia (MYP25, OMIM:617238) has been linked to mutations in P4HA2 gene. Seven family members complaining of reduced distance vision especially at dusk underwent complete ophthalmological examination. Whole-exome sequencing was performed to identify the gene responsible for myopia in the pedigree. Moderate myopia was diagnosed in the family which was associated to the novel missense variant c.1147A > G p.(Lys383Glu) in the prolyl 4-hydroxylase,alpha-polypeptide 2 (P4HA2) gene, which catalyzes the formation of 4-hydroxyproline residues in the collagen strands. In vitro studies demonstrated P4HA2 mRNA and protein reduced expression level as well as decreased collagen hydroxylation and deposition in mutated fibroblast primary cultures compared to healthy cell lines. This study suggests that P4HA2 mutations may lead to myopic axial elongation of eyeball as a consequence of quantitative and structural alterations of collagen. This is the first confirmatory study which associates a novel dominant missense variant in P4HA2 with myopia in Caucasian patients. Further studies in larger cohorts are advisable to fully clarify genotype-phenotype correlations

Launch of a product and patents : evidence from the US cardiovascular pharmaceutical sector

Recent literature on the role of patents in shaping competition between incumbents and new entrants shows mixed evidence, as patents can discourage entry into markets but may also encourage potential entrants by increasing profitability from research and development. The increasing use of patents as strategic weapons motivates this investigation of the impact of innovation on competition. In a case study of US pharmaceutical cardiovascular submarkets over the period 1988-1998, we use a panel probit model to study the impact of a firm\u2019s patents and rivals\u2019 patents in the firm\u2019s decision to launch new products. Our results show that the number of a firm\u2019s lagged patents encourages the firm\u2019s entry with new products, while rivals\u2019 initial stock of patents discourages entry, but more recent patents promote entry by opening new technological opportunities

An in vitro investigation of the influence of self-ligating brackets, low friction ligatures, and archwire on frictional resistance

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CFD-based methodology for the characterization of the combustion process of a passive pre-chamber gasoline engine

Pre-chamber (PC) ignition systems, enabling Turbulent Jet Ignition (TJI) combustion, represent a promising technology to extend the lean limit of Spark Ignition Internal Combustion Engines. Indeed, the higher ignition energy provided by the turbulent jets contributes to the limitation of combustion duration and variability even in diluted conditions. However, a detailed analysis of the combustion process is needed to maximize the performance of the system. More specifically, the interaction between the chemical and the turbulent scales are key factors in assessing the probabilities of main chamber (MC) ignition, determining the ignition pattern, and characterizing the combustion process. For this reason, the development of reliable numerical models is a crucial factor to pave the way toward a deeper understanding of details concerning TJI combustion. In the present work, a 3D-CFD numerical model was validated against experimental data at 4000 rpm, in stoichiometric and lean (i.e., λ = 1.2) conditions in a single-cylinder gasoline engine equipped with a passive pre-chamber. In both operations, the evolution of the turbulent combustion regimes over the whole combustion process was investigated, highlighting analogies and differences between the selected operative conditions. Additionally, a methodology to characterize the MC ignition and combustion process, able to describe the different phases of the interaction between PC and MC, and assess the thermal, turbulent, and chemical effects of the turbulent jets is presented

Neuroradiological findings in Alagille syndrome

Alagille syndrome (ALGS) is a multisystemic disease caused by mutations in genes of Notch pathway, which regulates embryonic cell differentiation and angiogenesis. Clinically, ALGS is characterized by cholestasis, cardiac defects, characteristic facial features, skeletal and ophthalmologic abnormalities. The aim of this review is to illustrate neuroradiological findings in ALGS, which are less well-known and prevalent, including cerebrovascular anomalies (such as aneurysms, dolichoectasia, Moyamoya syndrome and venous peculiarities), Chiari 1 malformation, craniosynostosis, intracranial hypertension, and vertebral anomalies (namely butterfly vertebra, hemivertebra, and craniocervical junction anomalies). Rarer cerebral midline malformations and temporal bone anomalies have also been described

ZCT 103/3 - Fizik III (Getaran, Gelombang dan Optik) FEB 04.

Wiki content templating enables reuse of content structures among wiki pages. In this paper we present a thorough study of this widespread feature, showing how its two state of the art models (functional and creational templating) are sub-optimal. We then propose a third, better, model called lightly constrained (LC) templating and show its implementation in the Moin wiki engine. We also show how LC templating implementations are the appropriate technologies to push forward semantically rich web pages on the lines of (lowercase) semantic web and microformats. ation performed by the wiki engine to deliver semantically rich web pages and give to authors simple interfaces (sometimes even invisible interfaces based on syntactic quirks!) to semantically annotate their content or to import semantic metadata

The Endocannabinoid System: A Putative Role in Neurodegenerative Diseases

BACKGROUND: Following the characterization of the chemical structure of D9-tetrahydrocannabinol (THC), the main psychoactive constituent of marijuana, researchers have moved on with scientific valuable explorations. OBJECTIVES: The aim of this review is to highlight the role of endocannabinoid system in neurodegenerative diseases. MATERIALS AND METHODS: The article is a critical analysis of the most recent data currently present in scientific literature on the subject; a qualitative synthesis of only the most significant articles has been performed. RESULTS: In central nervous system, endocannabinoids show a neuromodulatory function, often of retrograde type. This way, they play an important role in synaptic plasticity and in cognitive, motor, sensory and affective processes. In addition, in some acute or chronic pathologies of central nervous system, such as neurodegenerative and neuroinflammatory diseases, endocannabinoids can perform a pro-homeostatic and neuroprotective function, through the activation of CB1 and CB2 receptors. Scientific evidence shows that an hypofunction or a dysregulation of the endocannabinoid system may be responsible for some of the symptoms of diseases such as multiple sclerosis, amyotrophic lateral sclerosis, Huntington’s, Parkinson’s and Alzheimer’s diseases. CONCLUSIONS: The important role played by endocannabinoid system promises interesting developments, in particular to evaluate the effectiveness of new drugs in both psychiatry and neurology

Discrete model analysis of the critical current density measurements in superconducting thin films by a single coil inductive method

The critical current density of a superconducting film can be easily determined by an inductive and contactless method. Driving a sinusoidal current in a single coil placed in front of a superconducting sample, a non zero third harmonic voltage V_3 is induced in it when the sample goes beyond the Bean critical state. The onset of V_3 marks the value of current beyond which the sample response to the magnetic induction is no more linear. To take into account, in a realistic way, the magnetic coupling between the film and the coil we have developed a discrete model of the inducing and induced currents distribution. In the framework of this model the magnetic field profile on the sample surface and the coefficient linking the current flowing in the coil and the critical current density J_C of superconducting thin films is evaluated. The numerical results are checked measuring J_C of several thin films of YBa_2Cu_3O_(7-d) of known superconducting properties, used as a control material.Comment: to be published in Journal of Applied Physic