21 research outputs found
Topological quantization and degeneracy in Josephson-junction arrays
We consider the conductivity quantization in two-dimensional arrays of
mesoscopic Josephson junctions, and examine the associated degeneracy in
various regimes of the system. The filling factor of the system may be
controlled by the gate voltage as well as the magnetic field, and its
appropriate values for quantization is obtained by employing the Jain hierarchy
scheme both in the charge description and in the vortex description. The
duality between the two descriptions then suggests the possibility that the
system undergoes a change in degeneracy while the quantized conductivity
remains fixed.Comment: To appear in Phys. Rev.
Particle-Vortex Duality and the Modular Group: Applications to the Quantum Hall Effect and Other 2-D Systems
We show how particle-vortex duality implies the existence of a large
non-abelian discrete symmetry group which relates the electromagnetic response
for dual two-dimensional systems in a magnetic field. For conductors with
charge carriers satisfying Fermi statistics (or those related to fermions by
the action of the group), the resulting group is known to imply many, if not
all, of the remarkable features of Quantum Hall systems. For conductors with
boson charge carriers (modulo group transformations) a different group is
predicted, implying equally striking implications for the conductivities of
these systems, including a super-universality of the critical exponents for
conductor/insulator and superconductor/insulator transitions in two dimensions
and a hierarchical structure, analogous to that of the quantum Hall effect but
different in its details. Our derivation shows how this symmetry emerges at low
energies, depending only weakly on the details of dynamics of the underlying
systems.Comment: 22 pages, LaTeX, 2 figures, uses revte
Editorial Statement About JCCAP’s 2023 Special Issue on Informant Discrepancies in Youth Mental Health Assessments: Observations, Guidelines, and Future Directions Grounded in 60 Years of Research
Issue 1 of the 2011 Volume of the Journal of Clinical Child and Adolescent Psychology (JCCAP) included a Special Section about the use of multi-informant approaches to measure child and adolescent (i.e., hereafter referred to collectively as “youth”) mental health (De Los Reyes, 2011). Researchers collect reports from multiple informants or sources (e.g., parent and peer, youth and teacher) to estimate a given youth’s mental health. The 2011 JCCAP Special Section focused on the most common outcome of these approaches, namely the significant discrepancies that arise when comparing estimates from any two informant’s reports (i.e., informant discrepancies). These discrepancies appear in assessments conducted across the lifespan (Achenbach, 2020). That said, JCCAP dedicated space to understanding informant discrepancies, because they have been a focus of scholarship in youth mental health for over 60 years (e.g., Achenbach et al., 1987; De Los Reyes & Kazdin, 2005; Glennon & Weisz, 1978; Kazdin et al., 1983; Kraemer et al., 2003; Lapouse & Monk, 1958; Quay et al., 1966; Richters, 1992; Rutter et al., 1970; van der Ende et al., 2012). Thus, we have a thorough understanding of the areas of research for which they reliably appear when clinically assessing youth. For instance, intervention researchers observe informant discrepancies in estimates of intervention effects within randomized controlled trials (e.g., Casey & Berman, 1985; Weisz et al., 2017). Service providers observe informant discrepancies when working with individual clients, most notably when making decisions about treatment planning (e.g., Hawley & Weisz, 2003; Hoffman & Chu, 2015). Scholars in developmental psychopathology observe these discrepancies when seeking to understand risk and protective factors linked to youth mental health concerns (e.g., Hawker & Boulton, 2000; Hou et al., 2020; Ivanova et al., 2022). Thus, the 2011 JCCAP Special Section posed a question: Might these informant discrepancies contain data relevant to understanding youth mental health? Suppose none of the work in youth mental health is immune from these discrepancies. In that case, the answer to this question strikes at the core of what we produce―from the interventions we develop and implement, to the developmental psychopathology research that informs intervention development
Shape pattern recognition using a computable shape pattern representation
Properties of shapes and shape patterns are investigated in order to represent shape pattern knowledge for supporting shape pattern recognition. It is based on the notion that shape patterns are classified in terms of similarity of spatial relationships as well as physical properties. Methods for shape pattern recognition are explained and examples from an implementation are presented
Reconfigurable photo-induced doping of two-dimensional van der Waals semiconductors using different photon energies
Few-layer molybdenum ditelluride and tungsten diselenide field-effect transistors can be reversibly doped with different carrier types and concentrations using pulses of ultraviolet and visible light, allowing reconfigurable complementary metal-oxide-semiconductor circuits to be created. Two-dimensional semiconductors have a range of electronic and optical properties that can be used in the development of advanced electronic devices. However, unlike conventional silicon semiconductors, simple doping methods to monolithically assemble n- and p-type channels on a single two-dimensional semiconductor are lacking, which makes the fabrication of integrated circuitry challenging. Here we report the reversible photo-induced doping of few-layer molybdenum ditelluride and tungsten diselenide, where the channel polarity can be reconfigured from n-type to p-type, and vice versa, with laser light at different frequencies. This reconfigurable doping is attributed to selective light-lattice interactions, such as the formation of tellurium self-interstitial defects under ultraviolet illumination and the incorporation of substitutional oxygen in tellurium and molybdenum vacancies under visible illumination. Using this approach, we create a complementary metal-oxide-semiconductor (CMOS) device on a single channel, where the circuit functions can be dynamically reset from a CMOS inverter to a CMOS switch using pulses of different light frequencies.11Nsciescopu