The 23 year reminiscence of the SN1987A

Twenty three years ago on February 23, 1987, the explosion of the SN in the L.M.C. was observed both optically and by underground detectors. The optical observations were done in Chile and Australian observatories while the neutrino burst was detected by several underground experiments in the Northern Hemisphere, running at that time: Mt. Blanc in Italy, Kamioka in Japan, and Baksan in Russia and IMB in the USA. For the first time in the history of human existence, an astrophysical phenomenon has been observed in underground detectors. In this astrophysical event, the Mt. Blanc experiment detected five pulses on-line that were not at the same time, as detected by the other three detectors around five hours later. It is still not clear to astrophysicists why two bursts at two different times have been detected and how an SN can generate two neutrino bursts. After 23 years a model has proposed an explanation for a double stage collapse at two different times, as recently suggested by V.S. Imshennik and O. Ryazhskaya. In this paper, a detailed occurrence of something strange that happened on February 23rd is presented while most of the scientific information has been exhibited in other published papers

Fast Neural Network Predictions from Constrained Aerodynamics Datasets

Incorporating computational fluid dynamics in the design process of jets, spacecraft, or gas turbine engines is often challenged by the required computational resources and simulation time, which depend on the chosen physics-based computational models and grid resolutions. An ongoing problem in the field is how to simulate these systems faster but with sufficient accuracy. While many approaches involve simplified models of the underlying physics, others are model-free and make predictions based only on existing simulation data. We present a novel model-free approach in which we reformulate the simulation problem to effectively increase the size of constrained pre-computed datasets and introduce a novel neural network architecture (called a cluster network) with an inductive bias well-suited to highly nonlinear computational fluid dynamics solutions. Compared to the state-of-the-art in model-based approximations, we show that our approach is nearly as accurate, an order of magnitude faster, and easier to apply. Furthermore, we show that our method outperforms other model-free approaches

GEO and sustainable performance: The moderating role of GTD and environmental consciousness,

Purpose Congruent with the world-wide call to combat global warming concerns and advance intellectual capital (IC), organisations are being pressured to ensure that IC is managed effectively to encourage green initiatives. In this regard, green entrepreneurial orientation (GEO) is emerged as a relevant IC. GEO is recognised as a mitigating factor of environmental degradation in the literature. Although prior literature has observed the nexus between GEO and firm performance, the role of GEO in leveraging sustainable performance has been limitedly explored. This study explored the relationship between IC as a GEO and enterprises' sustainable performance through the moderating roles of environmental consciousness and green technology dynamism (GTD) in the context of two developing countries (Pakistan and Malaysia). Design/methodology/approach Data provided by 296 respondents from 264 manufacturing small and medium-sized enterprises (SMEs) in Pakistan and Malaysia were analysed through a three-wave research design. AMOS 23 software was used to perform covariance-based structural equation modelling (CB-SEM), while hierarchical regression analysis was applied using the SPSS 25 software to examine the causal relationships in the model. Findings IC as a GEO significantly influences sustainable performance, akin to environmental consciousness and GTD. Besides, GTD has a significant moderating effect between GEO and financial and environmental performance in Pakistan and Malaysia but not between GEO and social performance. Environmental consciousness has a significant moderating role in the impact of GEO on financial performance in Pakistan and Malaysia, but not on social and environmental performance. Practical implications The study's findings are useful for managers of Pakistani and Malaysian manufacturing SMEs to identify ways to encourage GEO to improve sustainable performance in their firms. The findings suggest that managers should effectively implement GTD and environmental consciousness to strengthen the GEO and sustainable performance relationship. Managers can use GEO concretely as a reference for the companies that intend to support the United Nation SDG-2030 agenda and to find new business opportunities for the implementation of sustainable development. Originality/value To the best of the authors' knowledge, this study is the first to examine the link between GEO and sustainable performance in developing countries such as Pakistan and Malaysia. Although the influence of various intangible assets or IC on sustainable performance has been widely examined in the literature, the role of GEO as IC has been limitedly explored. This study extends the literature by adding to the knowledge of GEO as a form of firms' IC that enhances boundary conditions in developing countries

An evolve-then-correct reduced order model for hidden fluid dynamics

In this paper, we put forth an evolve-then-correct reduced order modeling approach that combines intrusive and nonintrusive models to take hidden physical processes into account. Specifically, we split the underlying dynamics into known and unknown components. In the known part, we first utilize an intrusive Galerkin method projected on a set of basis functions obtained by proper orthogonal decomposition. We then formulate a recurrent neural network emulator based on the assumption that observed data is a manifestation of all relevant processes. We further enhance our approach by using an orthonormality conforming basis interpolation approach on a Grassmannian manifold to address off-design conditions. The proposed framework is illustrated here with the application of two-dimensional co-rotating vortex simulations under modeling uncertainty. The results demonstrate highly accurate predictions underlining the effectiveness of the evolve-then-correct approach toward realtime simulations, where the full process model is not known a priori

Hall-effect and resistivity measurements in CdTe and ZnTe at high pressure: Electronic structure of impurities in the zincblende phase and the semi-metallic or metallic character of the high-pressure phases

We carried out high-pressure resistivity and Hall-effect measurements in single crystals of CdTe and ZnTe up to 12 GPa. Slight changes of transport parameters in the zincblende phase of CdTe are consitent with the shallow character of donor impurities. Drastic changes in all the transport parameters of CdTe were found around 4 GPa, i.e. close to the onset of the cinnabar to rock-salt transition. In particular, the carrier concentration increases by more than five orders of magnitude. Additionally, an abrupt decrease of the resistivity was detected around 10 GPa. These results are discussed in comparison with optical, thermoelectric, and x-ray diffraction experiments. The metallic character of the Cmcm phase of CdTe is confirmed and a semi-metallic character is determined for the rock-salt phase. In zincblende ZnTe, the increase of the hole concentration by more than two orders of magnitude is proposed to be due to a deep-to-shallow transformation of the acceptor levels. Between 9 and 11 GPa, transport parameters are consistent with the semiconducting character of cinnabar ZnTe. A two orders of magnitude decrease of the resistivity and a carrier-type inversion occurs at 11 GPa, in agreement with the onset of the transition to the Cmcm phase of ZnTe. A metallic character for this phase is deduced.Comment: 20 pages, 4 figure

Juventud y cooperativismo en el Paraguay

Resumen de ponencias, debate y conclusiones del Encuentro de Jóvenes Cooperativistas. Organizado por la Cooperativa San Cristóbal Ltda., Asunción, 26 de noviembre de 1994.Contenido Presentación 1. Apertura 4. 1.1 Rodolfo Serafini. Cooperativa San Cristóbal. Comité de Educación 4. 1.2 Exposición del Sr. Julio López. Presidente del Comité de Educación y Vice Presidente de la Cooperativa San Cristóbal 4. 1.3 Exposición de Luis Caputo. BASE-IS. Programa de Juventud Rural 5. 1.4 Exposición de Fidel Agüero. Cooperativa Medalla Milagrosa 6. 1.5 Exposición de Fernando Ríos. Instituto Nacional de Cooperativismo 7. 1.6 Exposición de Enrique Riera. Viceministro de Educación 8. 2. La juventud Cooperativista: Su dimensión socio-política 11. 2.1 La juventud desde la óptica cooperativista 14. 2.2 Características ventajosas de la juventud 16. 3. Debate 18. 4. Plenaria y conclusiones. Participación de la juventud en la organización cooperativa 25. 4.1 Representantes del Grupo1. La situación actual del joven, con respecto a los obstáculos y a las oportunidades que encuentra el joven con respecto al cooperativismo 25. 4.2 Representantes del Grupo 2. La situación de la juventud en la cooperativa 28. 4.3 Representante del Grupo 3. Puntos sobre las principales causas de desempleo juvenil 31

Free field realization of the exceptional current superalgebra \hat{D(2,1;\a)}_k

The free-field representations of the D(2,1;\a) current superalgebra and the corresponding energy-momentum tensor are constructed. The related screening currents of the first kind are also presented.Comment: Latex file, 10 page