Measurement of Corner-Mode Coupling in Acoustic Higher-Order Topological Insulators

Recent developments of band topology have revealed a variety of higher-order topological insulators (HOTIs). These HOTIs are characterized by a variety of different topological invariants, making them different at a fundamental level. However, despite such differences, the fact that they all sustain higher-order topological boundary modes poses a challenge to phenomenologically tell them apart. This work presents experimental measurements of the coupling effects of topological corner modes (TCMs) existing in two different types of two-dimensional acoustic HOTIs. Although both HOTIs have a similar four-site square lattice, the difference in magnetic flux per unit cell dictates that they belong to different types of topologically nontrivial phases—one lattice possesses quantized dipole moments, but the other is characterized by quantized quadrupole moment. A link between the topological invariants and the response line shape of the coupled TCMs is theoretically established and experimentally confirmed. Our results offer a pathway to distinguish HOTIs experimentally.

(Un)Safe spaces for intersectional activism: Romani women’s responses to transnational political opportunities

This article investigates the responses of intersectional activists to the political opportunity spaces made for them by international organisations at the European transnational level. To do so, it uses Romani women’s activism and the Council of Europe as case studies, and develops a heuristic tool – the (Un)Safeness Response Line – that builds on five categories of analysis: compliance, compromise, contestation from within, opposition and denial. Mostly based on semi-structured and unstructured expert interviews conducted in 2016 and 2017, this study observes that Romnja activists have been mostly compliant with the political agendas of international organisations. Yet, they have not always perceived the opportunity spaces created for them as safe spaces. This has manifested in negotiating safeness and accepting compromises, as well as in strong opposition. This article shows that opportunity spaces for intersectional activisms are not enough, and that the quality of such spaces matters. Thus, it fosters a more critical approach to the study of contemporary social movements.<br /><br />Key messages<br /><ul><li>Creating political opportunity spaces for intersectional activisms is not enough, the quality of such spaces matters.</li><br /><li>It is only by perceiving and seizing political opportunity spaces as ‘good’ and ‘suitable’ that intersectional activists can make their voices heard and act as ‘agents of change’.</li><br /><li>Fostering a more critical approach and quality-oriented analyses to the study of political opportunities is needed.</li></ul>

Pseudotautological Question-Answer Unity in Russian Dialog: National Conditioning of the Models of Phatic Communication

Nationally determined models of phatic question-answer unities in the speech practice of native Russian speakers are considered. Particular attention is paid to the so-called pseudo-tautological question-answer unities of the type: - Where did you come here from? // - From there .... The question is raised about combining, when actualizing these unity, in speech, regulatory and metacommunicative functions. Two varieties of pseudotautological unity have been established: the response line in form corresponds to the initial interrogative (lexically and / or grammatically, phonetically, etc., cf. where - there, who - what , etc.); the response line in form repeats the initial interrogative line - in whole or in part. It is shown that in pseudotautological unities a special kind of pragmatic connection is realized - implicit, in which the initial and response lines are based on the appeal to conditions of success, presuppositions and presumptions, discourse implications, etc. It is concluded that the functioning of the phatic pseudotautological question-answer unities in the Russian dialogical discourse has a significant national conditionality: the emphasis in speech interaction is inevitably transferred to the interpersonal relations of the participants in the dialogue, to the value of communication in Russian speech practice.

Experimental Micromachining of Silicon with Nd-YAG Laser

This research centers on experimental laser-micromachining of silicon using solid state pulsed Nd:YAG laser. The laser is equipped with 3-axis controllers with resolution of 1 µm. The main objective is to find out the possibility of using this laser machining system to fabricate a micro feature on silicon. Simple straight lines were generated on silicon surface. The two process parameters – the laser traverse speed and pulse energy- were considered in the experimental design. Two forms of experiments were carried out: (1) processing with air assist gas and (2) processing without the assist gas using the same experimental design. Standard full factorial design of 3kwas used to design the experiments. Repeatability of the machine and nonlinearity were taken into account in the design by adding center points. Sequence of experiments was also randomized. Statistical analysis of experimental results could not show any significant factor. However, the surface plot did provide general information on desirable regions for the response line width, which was consistent with the published results. Micrograph study of the featured lines revealed that the laser processing without the assist gas produced preferable results.

Arterial [H+] and the ventilatory response to hypoxia in humans: influence of acetazolamide-induced metabolic acidosis

In this study, we investigated possible separate effects of H+ ions and CO2 on hypoxic sensitivity in humans. We also examined whether hypoxic sensitivity, conventionally defined as the ratio of (hypoxic − normoxic) ventilation over (hypoxic − normoxic) Hb oxygen saturation can also be estimated by taking the ratio (hypoxic − normoxic) ventilation over (logPaO2 hypoxia − logPaO2 normoxia), enabling one to measure the hypoxic response independently from potential confounding influences of changes in position of the Hb oxygen saturation curve. We used acetazolamide to induce a metabolic acidosis. To determine the acute hypoxic response (AHR), we performed step decreases in end-tidal Po2 to ∼50 Torr lasting 5 min each at three different constant end-tidal Pco2 levels. Nine subjects ingested 250 mg of acetazolamide or placebo every 8 h for 3 days in a randomized double-blind crossover design. The metabolic acidosis was accompanied by a rise in ventilation, a substantial fall in PaCO2, and a parallel leftward shift of the ventilatory CO2 response curve. In placebo, CO2 induced equal relative increases in hypoxic sensitivity (O2-CO2 interaction) regardless of the way it was defined. Acetazolamide shifted the response line representing the relationship between hypoxic sensitivity and arterial [H+] ([H+]a) to higher values of [H+]a without altering its slope, indicating that it did not affect the O2-CO2 interaction. So, in contrast to an earlier belief, CO2 and H+ have separate effects on hypoxic sensitivity. This was also supported by the finding that infusion of bicarbonate caused a leftward shift of the hypoxic sensitivity-[H+]a response lines in placebo and acetazolamide. A specific inhibitory effect of acetazolamide on hypoxic sensitivity was not demonstrated.