Industry competition in the long-run with particular reference to the petrochemical industry

Imperial Users onl

Αστρικοί Άνεμοι

Ο Αμερικανός αστροφυσικός E.N. Parker, υποστήριξε το 1958 ότι το ηλιακό στέμμα δεν είναι στατικό, αλλά διαστέλλεται με υπερηχητική ταχύτητα. Η υπερηχητική αυτή εκτόνωση του πλάσματος του Ήλιου ονομάστηκε ηλιακός άνεμος. Γενικά, ονομάζουμε αστρικό άνεμο τη συνεχή, υπερηχητική εκροή μάζας από ένα άστρο. Η δημιουργία ενός αστρικού ανέμου προϋποθέτει, μεταξύ άλλων, την άσκηση στα σωματίδια της αστρικής ατμόσφαιρας κάποιας δύναμης με ακτινική, προς τα έξω, συνιστώσα, η οποία από κάποια ακτίνα και πέρα υπερβαίνει τη δύναμη της βαρύτητας. Στην παρούσα εργασία μελετάμε ανέμους από θερμά (T>104K) άστρα μεγάλης μάζας (M 10-100 MSun), προγενέστερων φασματικών τύπων (Ο, Β, Α, Wolf-Rayet). Τον κυρίαρχο ρόλο στη δημιουργία αυτών των ανέμων παίζει η δύναμη ακτινοβολίας, ιδιαίτερα η συνιστώσα που σχετίζεται με τις φυσικές διαδικασίες που παράγουν τις φασματικές γραμμές. Εξετάζουμε δύο περιπτώσεις μοντελοποίησης αυτής της δύναμης: ως συνάρτηση της επιτάχυνσης (Castor, Abbot & Klein 1975, ApJ, 195, 157), και ως συνάρτηση της απόστασης (Muller, Vink 2008, A&A 492, 493). Στη δεύτερη περίπτωση η λύση μπορεί να εκφραστεί αναλυτικά μέσω της συνάρτησης W του Lambert.American astrophysicist E.N. Parker, claimed in 1958 that solar corona is not static, but expands at supersonic speed. This expansion is called solar wind. Generally, stellar wind is a continuous, supersonic mass outflow of a star. The creation of a stellar wind requires a force which exceeds gravity. In this thesis we study winds from hot (T>104K), massive (M=10-100M¬Sun), early-type (Ο, Β, Α, Wolf-Rayet) stars. The dominant role in the creation of these winds plays the radiation force, particularly its component that is associated with spectral lines. We consider two cases of this force: one as a function of acceleration (Castor, Abbot & Klein 1975, ApJ, 195, 157) and one as a function of distance (Muller, Vink 2008, A & A 492, 493). In the second case, the solution can be expressed analytically by the W function of Lambert

An adaptive memory programming framework for the resource-constrained project scheduling problem

The Resource-Constrained Project Scheduling Problem (RCPSP) is one of the most intractable combinatorial optimisation problems that combines a set of constraints and objectives met in a vast variety of applications and industries. Its solution raises major theoretical challenges due to its complexity, yet presenting numerous practical dimensions. Adaptive memory programming (AMP) is one of the most successful frameworks for solving hard combinatorial optimisation problems (e.g. vehicle routing and scheduling). Its success stems from the use of learning mechanisms that capture favourable solution elements found in high-quality solutions. This paper challenges the efficiency of AMP for solving the RCPSP, to our knowledge, for the first time in the literature. Computational experiments on well-known benchmark RCPSP instances show that the proposed AMP consistently produces high-quality solutions in reasonable computational times

Addressing nodal constraints on the capacity of railways

As demand for passenger and freight transport on Britain’s railways increases, providing additional capacity and making the best use of the existing infrastructure are priorities for the industry. Since the stations and junctions forming the nodes of the railway network tend to form the constraints on route and network capacity, improved understanding of their operation and capacity characteristics is particularly important. This paper describes research undertaken to improve the understanding of nodal capacity and capacity utilisation, and to route and schedule trains more efficiently through nodes, thus improving service quality and/or releasing capacity for additional train service

Utilizing Co-Creative Principles to Develop an E-Learning Platform for Interprofessional Training on Tinnitus: The Erasmus+ Project Tin-TRAC

Tinnitus treatment, diagnosis and management across Europe varies significantly. The lack of national clinical guidelines for tinnitus management in most European countries and the absence of a common language across all disciplines involved is reflected in the diversification of healthcare practices. Interprofessional Training for Tinnitus Researchers and Clinicians (Tin-TRAC) is an Erasmus+ project that aims to develop common educational ground in the form of an e-Learning platform, co-created by patients, researchers and clinicians, which is able to unify tinnitus diagnosis and treatment strategies across Europe. A pan-European thematic educational platform integrating the best practices and latest research achievements with regard to tinnitus diagnosis and management has the potential to act as a facilitator of the reduction of interdisciplinary and interregional practice diversification. A detailed analysis of the educational needs of clinicians and researchers across disciplines will be followed by the co-creative development of the curriculum. Reusable learning objects will incorporate the training contents and will be integrated in an open e-Learning platform. Tin-TRAC envisions that its output will answer the need to create a common language across the clinicians and researchers of different disciplines that are involved in tinnitus management, and reduce patients’ prolonged suffering, non-adherence and endless referral trajectories

The congested multicommodity network design problem

This paper studies a version of the fixed-charge multicommodity network design problem where in addition to the traditional costs of flow and design, congestion at nodes is explicitly considered. The problem is initially modeled as a nonlinear integer programming formulation and two solution approaches are proposed: (i) a reformulation of the problem as a mixed integer second order cone program to optimally solve the problem for small to medium scale problem instances, and (ii) an evolutionary algorithm using elements of iterated local search and scatter search to provide upper bounds. Extensive computational results on new benchmark problem instances and on real case data are presented

Optimizing emergency preparedness and resource utilization in mass-casualty incidents

This paper presents a response model for the aftermath of a Mass-Casualty Incident (MCI) that can be used to provide operational guidance for regional emergency planning as well as to evaluate strategic preparedness plans. A mixed integer programming (MIP) formulation is proposed for the combined ambulance dispatching, patient-to-hospital assignment, and treatment ordering problem. T he goal is to allocate effectively the limited resources during the response so as to improve patient outcomes, while the objectives are to minimize the overall response time and the total flow time required to treat all patients, in a hierarchical fashion. The model is solved via exact and MIP-based heuristic solution methods. The applicability of the model and the performance of the new methods are challenged on realistic MCI scenarios. We consider the hypothetical case of a terror attack at the New York Stock Exchange in Lower Manhattan with up to 150 trauma patients. We quantify the impact of capacity-based bottlenecks for both ambulances and available hospital beds. We also explore the trade-off between accessing remote hospitals for demand smoothing versus reduced ambulance transportation times

A Phase I Study of Pegylated Arginine Deiminase (Pegargiminase), Cisplatin, and Pemetrexed in Argininosuccinate Synthetase 1-Deficient Recurrent High-grade Glioma.

PURPOSE: Patients with recurrent high-grade gliomas (HGG) are usually managed with alkylating chemotherapy ± bevacizumab. However, prognosis remains very poor. Preclinically, we showed that HGGs are a target for arginine depletion with pegargiminase (ADI-PEG20) due to epimutations of argininosuccinate synthetase (ASS1) and/or argininosuccinate lyase (ASL). Moreover, ADI-PEG20 disrupts pyrimidine pools in ASS1-deficient HGGs, thereby impacting sensitivity to the antifolate, pemetrexed. PATIENTS AND METHODS: We expanded a phase I trial of ADI-PEG20 with pemetrexed and cisplatin (ADIPEMCIS) to patients with ASS1-deficient recurrent HGGs (NCT02029690). Patients were enrolled (01/16-06/17) to receive weekly ADI-PEG20 36 mg/m2 intramuscularly plus pemetrexed 500 mg/m2 and cisplatin 75 mg/m2 intravenously once every 3 weeks for up to 6 cycles. Patients with disease control were allowed ADI-PEG20 maintenance. The primary endpoints were safety, tolerability, and preliminary estimates of efficacy. RESULTS: Ten ASS1-deficient heavily pretreated patients were treated with ADIPEMCIS therapy. Treatment was well tolerated with the majority of adverse events being Common Terminology Criteria for Adverse Events v4.03 grade 1-2. The best overall response was stable disease in 8 patients (80%). Plasma arginine was suppressed significantly below baseline with a reciprocal increase in citrulline during the sampling period. The anti-ADI-PEG20 antibody titer rose during the first 4 weeks of treatment before reaching a plateau. Median progression-free survival (PFS) was 5.2 months (95% confidence interval (CI), 2.5-20.8) and overall survival was 6.3 months (95% CI, 1.8-9.7). CONCLUSIONS: In this recurrent HGG study, ADIPEMCIS was well tolerated and compares favorably to historical controls. Additional trials of ADI-PEG20 in HGG are planned

Activin-A co-opts IRF4 and AhR signaling to induce human regulatory T cells that restrain asthmatic responses

Type 1 regulatory T (Tr1) cells play a pivotal role in restraining human T-cell responses toward environmental allergens and protecting against allergic diseases. Still, the precise molecular cues that underlie their transcriptional and functional specification remain elusive. Here, we show that the cytokine activin-A instructs the generation of CD4+ T cells that express the Tr1-cell–associated molecules IL-10, inducible T-Cell costimulator (ICOS), lymphocyte activation gene 3 protein (LAG-3), and CD49b, and exert strongly suppressive functions toward allergic responses induced by naive and in vivo-primed human T helper 2 cells. Moreover, mechanistic studies reveal that activin-A signaling induces the activation of the transcription factor interferon regulatory factor (IRF4), which, along with the environmental sensor aryl hydrocarbon receptor, forms a multipartite transcriptional complex that binds in IL-10 and ICOS promoter elements and controls gene expression in human CD4+ T cells. In fact, IRF4 silencing abrogates activin-A– driven IL10 and ICOS up-regulation and impairs the suppressive functions of human activin-A–induced Tr1-like (act-A–iTr1) cells. Importantly, using a humanized mouse model of allergic asthma, we demonstrate that adoptive transfer of human act-A–iTr1 cells, both in preventive and therapeutic protocols, confers significant protection against cardinal asthma manifestations, including pulmonary inflammation. Overall, our findings uncover an activin-A–induced IRF4-aryl hydrocarbon receptor (AhR)–dependent transcriptional network, which generates suppressive human Tr1 cells that may be harnessed for the control of allergic diseases

Cabbage and fermented vegetables : From death rate heterogeneity in countries to candidates for mitigation strategies of severe COVID-19

Large differences in COVID-19 death rates exist between countries and between regions of the same country. Some very low death rate countries such as Eastern Asia, Central Europe, or the Balkans have a common feature of eating large quantities of fermented foods. Although biases exist when examining ecological studies, fermented vegetables or cabbage have been associated with low death rates in European countries. SARS-CoV-2 binds to its receptor, the angiotensin-converting enzyme 2 (ACE2). As a result of SARS-CoV-2 binding, ACE2 downregulation enhances the angiotensin II receptor type 1 (AT(1)R) axis associated with oxidative stress. This leads to insulin resistance as well as lung and endothelial damage, two severe outcomes of COVID-19. The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is the most potent antioxidant in humans and can block in particular the AT(1)R axis. Cabbage contains precursors of sulforaphane, the most active natural activator of Nrf2. Fermented vegetables contain many lactobacilli, which are also potent Nrf2 activators. Three examples are: kimchi in Korea, westernized foods, and the slum paradox. It is proposed that fermented cabbage is a proof-of-concept of dietary manipulations that may enhance Nrf2-associated antioxidant effects, helpful in mitigating COVID-19 severity.Peer reviewe