Fermion-induced quantum criticality in two-dimensional Dirac semimetals: Non-perturbative flow equations, fixed points and critical exponents

We establish a scenario where fluctuations of new degrees of freedom at a quantum phase transition change the nature of a transition beyond the standard Landau-Ginzburg paradigm. To this end we study the quantum phase transition of gapless Dirac fermions coupled to a $\mathbb{Z}_3$ symmetric order parameter within a Gross-Neveu-Yukawa model in 2+1 dimensions, appropriate for the Kekul\'e transition in honeycomb lattice materials. For this model the standard Landau-Ginzburg approach suggests a first order transition due to the symmetry-allowed cubic terms in the action. At zero temperature, however, quantum fluctuations of the massless Dirac fermions have to be included. We show that they reduce the putative first-order character of the transition and can even render it continuous, depending on the number of Dirac fermions $N_f$. A non-perturbative functional renormalization group approach is employed to investigate the phase transition for a wide range of fermion numbers. For the first time we obtain the critical $N_f$, where the nature of the transition changes. Furthermore, it is shown that for large $N_f$ the change from the first to second order of the transition as a function of dimension occurs exactly in the physical 2+1 dimensions. We compute the critical exponents and predict sizable corrections to scaling for $N_f =2$.Comment: 12+5 pages, 5 figure

Experimental Synthetic Aperture Radar with Dynamic Metasurfaces

We investigate the use of a dynamic metasurface as the transmitting antenna for a synthetic aperture radar (SAR) imaging system. The dynamic metasurface consists of a one-dimensional microstrip waveguide with complementary electric resonator (cELC) elements patterned into the upper conductor. Integrated into each of the cELCs are two diodes that can be used to shift each cELC resonance out of band with an applied voltage. The aperture is designed to operate at K band frequencies (17.5 to 20.3 GHz), with a bandwidth of 2.8 GHz. We experimentally demonstrate imaging with a fabricated metasurface aperture using existing SAR modalities, showing image quality comparable to traditional antennas. The agility of this aperture allows it to operate in spotlight and stripmap SAR modes, as well as in a third modality inspired by computational imaging strategies. We describe its operation in detail, demonstrate high-quality imaging in both 2D and 3D, and examine various trade-offs governing the integration of dynamic metasurfaces in future SAR imaging platforms

Management of Cervical Lymphadenitis in Children

Cervical lymphadenitis, defined as an acute symptomatic enlargement of the cervical lymph nodes, is a common condition in children of all ages. Most cases of cervical lymphadenitis in children are self-limited and can safely be monitored for spontaneous resolution over four to six weeks. (Strength of Recommendation [SOR]: C, based on expert opinion)

Periodic fever syndrome and autoinflammatory diseases

The concept of autoinflammatory disease as a new disease classification has resulted in a paradigm shift in our understanding of the the broad spectrum of immunological diseases. The effectiveness of interleukin-1 blockade in a variety of disorders has resulted in a marked reduction in suffering for many of these patients

Landscape ideology in the Greater Golden Horseshoe Greenbelt Plan: Negotiating material landscapes and abstract ideals in the city\u27s countryside

We analyze the role of landscape ideology in the recent Ontario Greater Golden Horseshoe (GGH) Greenbelt Plan. Focusing on the “Protected Countryside,” the major land-use designation in the Plan that structures the Greenbelt framework, we explore tensions between abstract ideals of countryside used by policy makers to elicit support for the Plan and people\u27s lived experience of material landscapes of the peri-urban fringe. Approaching “countryside” from the combined perspectives of landscape studies and political ecology, we show how the abstract ideals used to build support for the protection of countryside in the high-level political arena are in tension with existing material landscapes as people experience them. When implementing the Greenbelt Plan, the abstract ideals have to be applied at the landscape level through negotiation with municipalities, property owners, and other interests. In addition to drawing upon more conventionally legitimate explanations for landscape protection based on environmental science and land-use planning principles, the designation of Protected Countryside and the strategies used to implement the Protected Countryside designation at the local level suggest a tentative commitment to recognizing landscape values and collaborative environmental management processes in policy-making. As with any such normative land-use plan, the success of the Greenbelt Plan hinges on the long-term agreement between planning agencies and diverse publics. We demonstrate the usefulness of approaching environmental management challenges at the urban–rural interface by bringing the perspectives of landscape studies and political ecology into implementation processes for land-use management strategies like the Greenbelt. We argue that public participants deserve legitimate collaborative roles in negotiating just and desirable land uses based on their experiences, and provide observations on ways to bring contested goals and tools for achieving them into reflexive negotiations about how landscapes are and should be produced