Three-Nucleon Forces and Triplet Pairing in Neutron Matter

Papakonstantinou, P.,Clark, J. W. Springer-Verlag 2017 Journal of low temperature physics Vol.189 No.5

<P>The existence of superfluidity of the neutron component in the core of a neutron star, associated specifically with triplet wave pairing, is currently an open question that is central to interpretation of the observed cooling curves and other neutron-star observables. Ab initio theoretical calculations aimed at resolving this issue face unique challenges in the relevant high-density domain, which reaches beyond the saturation density of symmetrical nuclear matter. These issues include uncertainties in the three-nucleon (3N) interaction and in the effects of strong short-range correlations-and more generally of in-medium modification of nucleonic self-energies and interactions. A survey of existing solutions of the gap equations in the triplet channel demonstrates that the net impact on the gap magnitude of 3N forces, coupled channels, and mass renormalization shows extreme variation dependent on specific theoretical inputs, in some cases even pointing to the absence of a triplet gap, thus motivating a detailed analysis of competing effects within a well-controlled model. In the present study, we track the effects of the 3N force and in-medium modifications in the representative case of the channel, based on the Argonne two-nucleon (2N) interaction supplemented by 3N interactions of the Urbana IX family. Sensitivity of the results to the input interaction is clearly demonstrated. We point out consistency issues with respect to the simultaneous treatment of 3N forces and in-medium effects, which warrant further investigation. We consider this pilot study as the first step toward a systematic and comprehensive exploration of coupled-channel pairing using a broad range of 2N and 3N interactions from the current generation of refined semi-phenomenological models and models derived from chiral effective field theory.</P>

Flexural behavior of reinforced concrete beams strengthened with a hybrid inorganic matrix - steel fiber retrofit system

Papakonstantinou, Christos G.,Katakalos, Konstantinos Techno-Press 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.31 No.5

The aim of this study was to investigate the flexural behavior of reinforced concrete beams strengthened with a novel strengthening system. Concrete beams were strengthened with a hybrid retrofit system consisting of high strength steel cords impregnated in an inorganic fireproof matrix (Geopolymer). The strengthened reinforced concrete beams along with non-strengthened control beams were tested monotonically under four point bending loading conditions. Moreover, an analytical model is introduced, that can be used to analyze the flexural performance of the strengthened beams. The experimental results indicate that the failure of the strengthened beams was based on the yielding of the reinforcement in the tension face of the beams, followed by a local slippage of the steel cords. The flexural stiffness of the strengthened beams was significantly improved compared to the stiffness of the non-strengthened beams. In conclusion, the strengthening system can provide an effective alternative to commercially available systems.

Optimal levee installation planning for highway infrastructure protection against sea level rise

Papakonstantinou, Ilia,Lee, Jinwoo,Madanat, Samer Michel Elsevier 2019 TRANSPORTATION RESEARCH PART D-TRANSPORT AND ENVIR Vol.77 No.-

<P><B>Abstract</B></P> <P>Sea level rise predictions have motivated research towards the protection of shoreline infrastructures, including transportation systems. Transportation network interactions in cases of inundation can lead to severe disruptions that cause capacity and accessibility reduction and thus considerable delays, especially due to congestion feedback, because congestion occurring due to an inundated link or a link that becomes isolated through inundation of one of its nodes can lead to delays in other parts of the network, due to queue spillback or traffic rerouting. This paper describes a decision tool to support infrastructure protection planning against sea level rise. A simulation-based optimization model is designed to minimize delays occurring in a transportation system under inundation. The model considers budget constraints, hydrodynamic interactions within the shoreline, as well as traffic assignment in the network. The case study focuses on San Francisco Bay area, for a 0.5 m sea level rise that is expected in 2054 and may increase highway users’ travel time by 37%. The results show that the optimal strategies vary according to the available budget, and that there exist relatively critical shorelines to protect in order to reduce the traffic disruptions. We anticipate our research to provide a general framework for transportation infrastructure protection planning against sea level rises.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A simulation based bi-level model minimizes network delays due to inundations. </LI> <LI> Budget constraints, hydrodynamic and traffic interactions are considered. </LI> <LI> Findings are applied to a real world network in California for 0.5 m sea level rise. </LI> <LI> The optimal strategies vary according to the available budget. </LI> <LI> There exist critical shorelines to protect, to reduce the traffic disruptions. </LI> </UL> </P>

Isoscalar and neutron modes in theE1spectra of Ni isotopes and the relevance of shell effects and the continuum

Papakonstantinou, P.,Hergert, H.,Roth, R. American Physical Society 2015 PHYSICAL REVIEW C - Vol.92 No.3

Density dependence of the nuclear energy-density functional

Papakonstantinou, Panagiota,Park, Tae-Sun,Lim, Yeunhwan,Hyun, Chang Ho American Physical Society 2018 Physical Review C Vol.97 No.1

<P>Conclusions: Having been already determined for homogeneous matter, a functional of the present form can be mapped onto extended Skyrme-type functionals in a straightforward manner, as we outline here, for applications to finite nuclei. At the same time, the statistical analysis can be extended to higher orders and for different microscopic (ab initio) calculations with sufficient pseudodata points and for polarized matter.</P>

From Chiral $NN(N)$ Interactions to Giant and Pygmy Resonances via Extended RPA

Papakonstantinou, P.,Trippel, R.,Roth, R. Institute of Physics, Jagellonian University 2017 ACTA PHYSICA POLONICA SERIES B Vol.48 No.3

Figurae in Interrogando et in Respondendo: Dialogisme et Débat Judiciaire selon la Théorie de Quintilien

Nephele Papakonstantinou 한국서양고전학회 2019 西洋古典學硏究 Vol.58 No.3

In Quintilian’s view, the discursive configuration that underlies the verbal confrontation between accuser and accused, is based on two speech acts: ‘to question’ and ‘to answer’. These stress the need for the speaker to dominate the enunciative game, by asking questions that modulate the responses of the addressee. The judicial debate - the verbal duel that takes the form of the dialogue - is envisaged here in relation to the figured questions and answers, as discussed by Quintilian in The Orator’s Education book IX. Drawing on the notion of dialogism, we propose a classification system for these figures of thought according to two criteria: prior utterances and future utterances. The aim is to contribute to the clarification of the conception of dialogue in Latin rhetoric as a means for engaging in a clearly antagonistic interaction.

Flexural behavior of reinforced concrete beams strengthened with a hybrid inorganic matrix - steel fiber retrofit system

Christos G. Papakonstantinou,Konstantinos Katakalos 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.31 No.5

The aim of this study was to investigate the flexural behavior of reinforced concrete beams strengthened with a novel strengthening system. Concrete beams were strengthened with a hybrid retrofit system consisting of high strength steel cords impregnated in an inorganic fireproof matrix (Geopolymer). The strengthened reinforced concrete beams along with non-strengthened control beams were tested monotonically under four point bending loading conditions. Moreover, an analytical model is introduced, that can be used to analyze the flexural performance of the strengthened beams. The experimental results indicate that the failure of the strengthened beams was based on the yielding of the reinforcement in the tension face of the beams, followed by a local slippage of the steel cords. The flexural stiffness of the strengthened beams was significantly improved compared to the stiffness of the non-strengthened beams. In conclusion, the strengthening system can provide an effective alternative to commercially available systems.

Lobectomy due to Pulmonary Vein Occlusion after Radiofrequency Ablation for Atrial Fibrillation

Nikolaos A. Papakonstantinou,Charalambos Zisis,Charikleia Kouvidou,Grigoris Stratakos 대한흉부외과학회 2018 Journal of Chest Surgery (J Chest Surg) Vol.51 No.4

Radiofrequency ablation is an effective treatment for atrial fibrillation. Pulmonary vein stenosis/occlusion is one of its rare complications. Herein, the case of a 50-year-old man with hemoptysis and migratory pulmonary infiltrations after transcatheter radiofrequency ablation for atrial fibrillation is presented. Initially, pneumonia, interstitial pulmonary disease, or lung cancer was suspected, but wedge resection revealed hemorrhagic infiltrations. Chest computed tomography pulmonary angiography detected no left superior pulmonary vein due to its total occlusion, and left upper lobectomy was performed. Post-ablation pulmonary vein occlusion must be strongly suspected in cases of migratory pulmonary infiltrations and/or hemoptysis.

Epidemiology, Microbiological and Clinical Features, Treatment, and Outcomes of Infective Endocarditis in Crete, Greece

Panteleimon E. Papakonstantinou,George Samonis,Angeliki M. Andrianaki,Maria Christofaki,Dimitra Dimopoulou,John Papadakis,Achilleas Gikas,Diamantis P. Kofteridis 대한감염학회 2018 Infection and Chemotherapy Vol.50 No.1

Background: This study aimed to evaluate the epidemiology, clinical and microbiological features, treatment, and outcomes of infective endocarditis (IE) on the island of Crete, a region with high levels of antimicrobial resistance. Materials and Methods: Medical records of all hospitalized patients diagnosed with IE at the University Hospital of Heraklion, Crete, Greece, from 1995 to 2015, were retrospectively reviewed. Patients who met the modified Duke’s criteria for definite or possible IE were included. Results: A total of 82 IE patients (median age 67 [range 21–86] years) were included. Most patients suffered from left-sided IE (94%), while most cases of infection occurred in native valves (53.6%). Systemic inflammatory response syndrome criteria were lacking in almost half of the patient population. The leading causative microorganism was Staphylococcus aureus, isolated in 24 cases (29%), followed by Streptococcus spp. in 15 (18%) and Enterococcus spp. in 12 (14.5%). A number of rare and difficult to treat microorganisms had been identified, such as Gemella morbillorum in four cases (4.5%), Streptococcus lugdunensis in two (2.5%) and Streptococcus pneumoniae in one (1%). One patient was serologically positive for Coxiella burnetii (1%). All patients received empirical antimicrobial treatment, proven appropriate in 39 blood culture-positive patients (56.5%). Thirteen (16%) patients were classified as culture negative. Seven patients (8.5%) were surgically treated. In-hospital death occurred in 9 patients (11%). Conclusion: Changes in IE profile requires continuous epidemiological updates. Staphylococcus and Streptococcus spp. remain the most common etiologic agents. However, the presence of uncommon and/or difficult to treat pathogens raise concerns on the appropriate prophylaxis as well as empirical treatment.