Asymmetric topological pumping in nonparaxial photonics

Topological photonics was initially inspired by the quantum-optical analogy between the Schrödinger equation for an electron wavefunction and the paraxial equation for a light beam. Here, we reveal an unexpected phenomenon in topological pumping observed in arrays of nonparaxial optical waveguides where the quantum-optical analogy becomes invalid. We predict theoretically and demonstrate experimentally an asymmetric topological pumping when the injected field transfers from one side of the waveguide array to the other side whereas the reverse process is unexpectedly forbidden. Our finding could open an avenue for exploring topological photonics that enables nontrivial topological phenomena and designs in photonics driven by nonparaxiality.

Unexpected phenomenon in a conventional system: synthesis of raspberry-like hollow periodic mesoporous organosilica with controlled structure in one continuous step

We put forward a facile method to fabricate raspberry-like hollow PMO with tunable morphology, derived from an interesting phenomenon in preparing conventional PMO.

SARS-CoV-2: Remarks on the COVID-19 Pandemic

The COVID-19 pandemic developing rapidly in 2020 is triggered by the emergence of a new human virus—SARS-CoV-2. The emergence of a new virus is not an unexpected phenomenon and has been predicted for many years. Since the virus has spread all over the world, it will be very difficult or even impossible to eradicate it. A necessary condition for complete or partial elimination of the virus is to have an effective vaccine. It is possible that SARS-CoV-2 will become milder in the next few years and COVID-19 will then only threaten individuals from risk groups.

¿Hubo checas en el Madrid de la Guerra Civil? Estudio comparado de la policía política soviética y los comités revolucionarios españoles (verano-otoño 1936) = Were there “Checas” in the Madrid of the Civil War? Comparative study of the Soviet political police and the Spanish revolutionary committees (summer-autumn 1936)

Resumen: Ante el fenómeno inesperado que tuvo el golpe de estado y la derrota de la sublevación sobre el Estado republicano, surgieron toda una serie de micropoderes que intentaron y compitieron entre sí por ocupar el espacio que había dejado vacío el Gobierno. Estos micropoderes, comités revolucionarios en su mayoría, no solo persiguieron ganar la guerra, sino iniciar y asentar un proceso revolucionario, contrapuesto al modelo de estado Republicano. Estos centros, al ejercer la justicia popular, fueron catalogados por los sublevados como “checas”, ligando su imagen al modelo de policía política soviético, la Cheká. En este trabajo se va a analizar el término checa, comparando los dos sistemas, el ruso y el español, para valorar si este concepto ayuda o entorpece nuestra comprensión sobre un fenómeno tan complejo como fue el de la revolución.Palabras clave: Guerra civil, Cheká, Violencia, comités, Madrid.Abstract: Faced with the unexpected phenomenon of the coup d'état and the defeat of the revolt against the republican state, a whole series of micro-powers arose that tried and competed with each other to occupy the space left by the government. These micro-powers, revolutionary committees for the most part, not only sought to win the war, but to initiate and settle a revolutionary process, as opposed to the Republican state model. These centers, in exercising popular justice, were labeled by the insurgents as "Checa", linking their image to the Soviet political police model, the Cheká. In this paper we will analyze the Cheká term, comparing the two systems, Russian and Spanish, to assess whether this concept helps or hinders our understanding of a phenomenon as complex as the revolution.Keywords: Civil war, Cheká, Violence, committees, Madrid.

السلفية والسياسة: حالة ماليزية

“Political salafism” is among the unexpected phenomenon emerge as a result of Arab Spring. It is observable through active involvement of salafi groups in politics in certain countries affected by revolutions. However, salafī–political advocators seems emerged earlier in Malaysia, compare to their counterparts in Egypt. Malaysian Salafi joined themselves in UMNO party (the United Malays National Organization) in 2009, and justified their involvement in the party as following salafi method, based on the notion of “absolute obedience to the ruler,” ‘prohibition of secession from the ruler,” and “necessity renders prohibited things permissible” Such involvement in political life is considered as bringing mileage to the salafī as well as the political party itself, even though the involvement initially based on gaining certain political benefit. Using historical and descriptive methodology, this article attempts to characterize raison detré as well as religious motives underneath the framework of those salafī advocators. Keywords: Salafī, ‘Aqīdah, Politics, UMNO, Malaysia

Characterization of surge superposition following 2-stage load rejection in hydroelectric power plant

When calculating the maximum upsurge in surge tank due to load rejection in a hydroelectric power plant, it has been natural and customary to believe that the maximum surge amplitude occurs in simultaneous load rejection of all units at 100% load. As 2-stage load rejection (2-stage LR), involving a step-wise reduction in load, is not considered since it is assumed to produce less severe surge conditions. This study formulates the surge superposition associated with 2-stage LR and shows, surprisingly but significantly, that such 2-stage LR sometimes produces more severe surge conditions than simultaneous and complete load rejection (SCLR). The results indicate that this unexpected phenomenon is ascribable to the resistant effect of throttled surge tank, whose increase will lead to a greater difference in the maximum upsurges between 2-stage LR and SCLR conditions. Different time intervals during 2-stage LR correspond to different maximum upsurges. The analytical formula predicting the worst interval time is derived exactly and verified with two numerical cases.