Microwave studies of the fractional Josephson effect in HgTe-based Josephson junctions

The rise of topological phases of matter is strongly connected to their potential to host Majorana bound states, a powerful ingredient in the search for a robust, topologically protected, quantum information processing. In order to produce such states, a method of choice is to induce superconductivity in topological insulators. The engineering of the interplay between superconductivity and the electronic properties of a topological insulator is a challenging task and it is consequently very important to understand the physics of simple superconducting devices such as Josephson junctions, in which new topological properties are expected to emerge. In this article, we review recent experiments investigating topological superconductivity in topological insulators, using microwave excitation and detection techniques. More precisely, we have fabricated and studied topological Josephson junctions made of HgTe weak links in contact with two Al or Nb contacts. In such devices, we have observed two signatures of the fractional Josephson effect, which is expected to emerge from topologically-protected gapless Andreev bound states. We first recall the theoretical background on topological Josephson junctions, then move to the experimental observations. Then, we assess the topological origin of the observed features and conclude with an outlook towards more advanced microwave spectroscopy experiments, currently under development.Comment: Lectures given at the San Sebastian Topological Matter School 2017, published in "Topological Matter. Springer Series in Solid-State Sciences, vol 190. Springer

RD39 Status Report 2009

RD39 Status Report 2009. CERN RD39 Collaboration is developing super-radiation hard cryogenic silicon detectors for applications of LHC experiments and their future upgrades. The activities of RD39 Collaboration were focused in 2009 on concept of charge injected detector (CID)

The interplay of matrix metalloproteinase-8, transforming growth factor-beta 1 and vascular endothelial growth factor-C cooperatively contributes to the aggressiveness of oral tongue squamous cell carcinoma

Background: Matrix metalloproteinase-8 (MMP-8) has oncosuppressive properties in various cancers. We attempted to assess MMP-8 function in oral tongue squamous cell carcinoma (OTSCC). Methods: MMP-8 overexpressing OTSCC cells were used to study the effect of MMP-8 on proliferation, apoptosis, migration, invasion and gene and protein expression. Moreover, MMP-8 functions were assessed in the orthotopic mouse tongue cancer model and by immunohistochemistry in patient samples. Results: MMP-8 reduced the invasion and migration of OTSCC cells and decreased the expression of MMP-1, cathepsin-K and vascular endothelial growth factor-C (VEGF-C). VEGF-C was induced by transforming growth factor-beta 1 (TGF-beta 1) in control cells, but not in MMP-8 overexpressing cells. In human OTSCC samples, low MMP-8 in combination with high VEGF-C was an independent predictor of poor cancer-specific survival. TGF-beta 1 treatment also restored the migration of MMP-8 overexpressing cells to the level of control cells. In mouse tongue cancer, MMP-8 did not inhibit metastasis, possibly because it was eliminated in the peripheral carcinoma cells. Conclusions: The suppressive effects of MMP-8 in OTSCC may be mediated through interference of TGF-beta 1 and VEGF-C function and altered proteinase expression. Together, low MMP-8 and high VEGF-C expression have strong independent prognostic value in OTSCC.Peer reviewe

A “Good” Explanation of Five Puzzles about Reasons

[Extract] What does it mean for something, like the fact that rain is forecast, to be a normative reason for an action, like taking your umbrella, or attitude, like believing it will rain? According to a popular view, concepts of “reasons” are all concepts of some kind of explanation.1 But explanations of what? On one way of developing this idea, the concept of a normative reason for an agent S to do A is that of an explanation why it would be good (in some way, to some degree) for S to do A.2 This Reasons as Explanations of Goodness hypothesis (REG) has numerous virtues and champions. But like every theory of normative reasons it faces some significant challenges, which prompt many more philosophers to be skeptical that it can account for all normative reasons. This paper demonstrates how five different puzzles about normative reasons can be solved by paying attention to how the concept of goodness is context‐sensitive—and how this implies that talk about reasons is also context‐sensitive. Rather than asking simply whether certain facts are reasons for S to do A, we need to explore how context affects whether it is correct to describe a fact as “a reason” for S to do A

Analysis for water conflict transformation

This article proposes and fleshes out an analytical method designed to support efforts to transform inequitable and unsustainable transboundary water arrangements. Such ‘transformative analysis’ leverages socio-ecological thinking to critically evaluate the processes that have established and maintain an arrangement, including hydro-diplomacy itself. Transformative analysis facilitates the interpretation of strategies to deflect transformation, identification of destructive forms of cooperation, and strategic classification of opportunities for transformation. The assertions are premised on an understanding of the particularities of water conflict, and followed by a discussion of ways researchers may overcome the challenges inherent in the method

Models of a New World: towards a Synthesis

Three alternative world orders can be imagined in the post-World War II international relations. During most of the Cold War a bipolar order, centered on the possession of nuclear weapons, existed. This world order was incomplete, however. The United States and the Soviet Union faced each other with equal capacity to destroy each other, but in terms of economic and global influence the United States was superior. The strengthening of economic and technological dynamics increased further the U.S. influence, but also sparked the power of non-states actors, including transnational corporations and banks, independent of states. Simultaneously with the globalization of the world, one could witness the rise of non-state actors in the military and political fields. The emergence of the world order of the third type has sometimes been called the neomedieval world in which some central tenets of feudalism has re-emerged. None of these world order models can be said to dominate in today’s world and none of them is likely to emerge victorious any time soon. In recent times., globalization has suffered from various setbacks and state-centric relations have reemerged. Their focus is not, however, any more on the military competition between the United States and Russia, although some of its elements remain in the arms competition between them. Globalization has brought in new ingredients in the rivalries between states and it has appeared most visibly in the U.S.-Chinese rivalry for economic and technological dominance of the globalized world economy. In other words, a new type of economic bipolarity is winning ground and is only secondarily manifesting itself in military relations. Patterns of warfare has in recent decades been colored by fighting of non-state military forces and the rise of new feudal patterns of behavior, but they have not been pronounced enough to justify the labeling of the entire world order by the name

Reflection on peer reviewing as a pedagogical tool in higher education

Abstract Previous research has emphasized both the importance of giving and receiving peer feedback for the purpose of active learning, as well as of university students’ engagement in reflection to improve learning outcomes. However, requiring students to explicitly reflect on peer reviewing is an understudied learning activity in higher education that may contribute to the utilization of peer-feedback and promote further learning. In this study, we suggest reflection on peer reviewing as one approach to providing a platform for students to engage in reflective practices and for stimulating active learning in higher education, and to make that learning visible to the educator. We examine 26 undergraduate students’ reflections on peer-review to identify categories of reflection and what students have learnt from the peer reviewing process. Our findings reveal six different categories of reflection suggesting students’ active engagement in learning and pointing to the ways educators can direct and instruct students how to reflect. We discuss how these findings can inform university lecturers in the use of reflection upon peer reviewing as a pedagogical tool in higher education