81 research outputs found
How well are we doing relative to other States? Interstate Highway Bridge Spending and Performance Comparisons across the States of the Union
Interaction Driven Quantum Hall Wedding cake-like Structures in Graphene Quantum Dots
Quantum-relativistic matter is ubiquitous in nature; however it is
notoriously difficult to probe. The ease with which external electric and
magnetic fields can be introduced in graphene opens a door to creating a
table-top prototype of strongly confined relativistic matter. Here, through a
detailed spectroscopic mapping, we provide a spatial visualization of the
interplay between spatial and magnetic confinement in a circular graphene
resonator. We directly observe the development of a multi-tiered "wedding
cake"-like structure of concentric regions of compressible/incompressible
quantum Hall states, a signature of electron interactions in the system.
Solid-state experiments can therefore yield insights into the behaviour of
quantum-relativistic matter under extreme conditions
Spiritual care for cancer patients in Iran
Background: Studies have shown that a return to spirituality is a major coping response in cancer patients so that therapists can adopt a holistic approach by addressing spirituality in their patient care. The present study was conducted to develop a guideline in the spiritual field for healthcare providers who serve cancer patients in Iran. Materials and Methods: Relevant statements were extracted from scientific documents that through study questions were reviewed and modified by a consensus panel. Results: The statements were arranged in six areas, including spiritual needs assessment, spiritual care candidates, the main components of spiritual care, spiritual care providers, the settings of spiritual care and the resources and facilities for spiritual care. Conclusions: In addition to the development and preparation of these guidelines, health policy-makers should also seek to motivate and train health service providers to offer these services and facilitate their provision and help with widespread implementation
Users, Planners, and Governments Perspectives: A Public Survey on Autonomous Vehicles Future Advancements
Autonomous vehicles (AVs) are expected to change driving perspectives once they are available in the markets. This type of vehicle has received substantial attention lately from media and researchers. This technology is still under rapid advancements, and further research studies are needed to address the potential outcomes, opportunities, and challenges. The fuel system of the AVs is expected to be electrical; therefore, this study addresses the current status of electric vehicles (EVs), including charging time, charging type, and driving range. The study also discusses the barriers that may hindrance the transformation to AVs from the users, planners, and government perspectives. These barriers include the current charging stations of EVs, which provide 2kW power. These stations can be insufficient for the AVs since these cars are expected to utilize advanced sensors and computers. The authors also propose comprehensive recommendations that could facilitate the so-called transformation of EVs to AVs and AVs' associated marketing. The authors found out that conducting a survey is essential to observe the public perception, and marketing and communication plans are essential to educating the public regarding AVs’ features and advantages. Also, a collaboration between auto manufacturers and planners is critical to the success of these vehicles. Finally, a public survey which consisted of 95 participants were conducted to examine the general perspective as surveys are necessary to assist planners, governments and automakers for their future movement toward a sustainable transportation system
Multicomponent fractional quantum Hall effect in graphene
We report observation of the fractional quantum Hall effect (FQHE) in high
mobility multi-terminal graphene devices, fabricated on a single crystal boron
nitride substrate. We observe an unexpected hierarchy in the emergent FQHE
states that may be explained by strongly interacting composite Fermions with
full SU(4) symmetric underlying degrees of freedom. The FQHE gaps are measured
from temperature dependent transport to be up 10 times larger than in any other
semiconductor system. The remarkable strength and unusual hierarcy of the FQHE
described here provides a unique opportunity to probe correlated behavior in
the presence of expanded quantum degrees of freedom.Comment: 5 pages, 3 figure
Tuning a Circular p-n Junction in Graphene from Quantum Confinement to Optical Guiding
The motion of massless Dirac-electrons in graphene mimics the propagation of
photons. This makes it possible to control the charge-carriers with components
based on geometrical-optics and has led to proposals for an all-graphene
electron-optics platform. An open question arising from the possibility of
reducing the component-size to the nanometer-scale is how to access and
understand the transition from optical-transport to quantum-confinement. Here
we report on the realization of a circular p-n junction that can be
continuously tuned from the nanometer-scale, where quantum effects are
dominant, to the micrometer scale where optical-guiding takes over. We find
that in the nanometer-scale junction electrons are trapped in states that
resemble atomic-collapse at a supercritical charge. As the junction-size
increases, the transition to optical-guiding is signaled by the emergence of
whispering-gallery modes and Fabry-Perot interference. The creation of tunable
junctions that straddle the crossover between quantum-confinement and
optical-guiding, paves the way to novel design-architectures for controlling
electronic transport.Comment: 16 pages, 4 figure
An On/Off Berry Phase Switch in Circular Graphene Resonators
The phase of a quantum state may not return to its original value after the
system's parameters cycle around a closed path; instead, the wavefunction may
acquire a measurable phase difference called the Berry phase. Berry phases
typically have been accessed through interference experiments. Here, we
demonstrate an unusual Berry-phase-induced spectroscopic feature: a sudden and
large increase in the energy of angular-momentum states in circular graphene
p-n junction resonators when a small critical magnetic field is reached. This
behavior results from turning on a -Berry phase associated with the
topological properties of Dirac fermions in graphene. The Berry phase can be
switched on and off with small magnetic field changes on the order of 10 mT,
potentially enabling a variety of optoelectronic graphene device applications
Magnetic Catalysis and Quantum Hall Ferromagnetism in Weakly Coupled Graphene
We study the realization in a model of graphene of the phenomenon whereby the
tendency of gauge-field mediated interactions to break chiral symmetry
spontaneously is greatly enhanced in an external magnetic field. We prove that,
in the weak coupling limit, and where the electron-electron interaction
satisfies certain mild conditions, the ground state of charge neutral graphene
in an external magnetic field is a quantum Hall ferromagnet which spontaneously
breaks the emergent U(4) symmetry to U(2)XU(2).
We argue that, due to a residual CP symmetry, the quantum Hall ferromagnet
order parameter is given exactly by the leading order in perturbation theory.
On the other hand, the chiral condensate which is the order parameter for
chiral symmetry breaking generically obtains contributions at all orders. We
compute the leading correction to the chiral condensate. We argue that the
ensuing fermion spectrum resembles that of massive fermions with a vanishing
U(4)-valued chemical potential. We discuss the realization of parity and charge
conjugation symmetries and argue that, in the context of our model, the charge
neutral quantum Hall state in graphene is a bulk insulator, with vanishing
longitudinal conductivity due to a charge gap and Hall conductivity vanishing
due to a residual discrete particle-hole symmetry.Comment: 35 page
Toxomerus duplicatus Wiedemann, 1830 (Diptera: Syrphidae) preying on Microtheca spp. (Coleoptera: Chrysomelidae) larvae
Skeletal Morphology of Opius dissitus and Biosteres carbonarius (Hymenoptera: Braconidae), with a Discussion of Terminology
The Braconidae, a family of parasitic wasps, constitute a major taxonomic challenge with an estimated diversity of 40,000 to 120,000 species worldwide, only 18,000 of which have been described to date. The skeletal morphology of braconids is still not adequately understood and the terminology is partly idiosyncratic, despite the fact that anatomical features form the basis for most taxonomic work on the group. To help address this problem, we describe the external skeletal morphology of Opius dissitus Muesebeck 1963 and Biosteres carbonarius Nees 1834, two diverse representatives of one of the least known and most diverse braconid subfamilies, the Opiinae. We review the terminology used to describe skeletal features in the Ichneumonoidea in general and the Opiinae in particular, and identify a list of recommend terms, which are linked to the online Hymenoptera Anatomy Ontology. The morphology of the studied species is illustrated with SEM-micrographs, photos and line drawings. Based on the examined species, we discuss intraspecific and interspecific morphological variation in the Opiinae and point out character complexes that merit further study
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