2,000 research outputs found
Model Evidence of a Superconducting State with a Full Energy Gap in Small Cuprate Islands
We investigate subdominant order parameters stabilizing at low temperatures in nanoscale high-Tc cuprate islands, motivated by the recent observation of a fully gapped state in nanosized YBa2Cu3O7-δ[D. Gustafsson et al., Nature Nanotech. 8, 25 (2013)]. Using complementary quasiclassical and tight-binding Bogoliubov–de Gennes methods, we show on distinctly different properties dependent on the symmetry being dx2-y2 Ăľ is or dx2-y2 Ăľ idxy. We find that a surface-induced dx2-y2 Ăľ is phase creates a global spectroscopic gap which increases with an applied magnetic field, consistent with experimental observation
The business of genomic testing: a survey of early adopters
Purpose: The practice of genomic (or personalized ) medicine requires the availability of appropriate diagnostic testing. Our study objective was to identify the reasons for health systems to bring next-generation Sequencing into their clinical laboratories and to understand the process by which such decisions were made. Such information may be of value to other health systems seeking to provide next-generation sequencing-testing to their patient populations. Methods: A standardized open-ended interview was conducted With the laboratory medical directors and/or department of pathology chairs of 13 different academic institutions in 10 different states. Results: Genomic testing for cancer dominated the institutional decision making, with three primary reasons: more effective delivery of cancer care, the perceived need for institutional leadership in the field of genomics, and the premise that genomics will eventually be cost-effective. Barriers to implementation included implementation cost; the time and effort needed to maintain this newer testing; challenges in interpreting genetic variants; establishing the bioinformatics infrastructure; and curating data from medical, ethical, and legal standpoints. Ultimate success depended on alignment with institutional strengths and priorities and working closely with institutional clinical programs. Conclusion: These early adopters uniformly viewed genomic analysis as an imperative for developing their expertise in the implementation and practice of genomic medicine
An Innovative Interactive Modeling Tool to Analyze Scenario-Based Physician Workforce Supply and Demand
Effective physician workforce management requires that the various organizations comprising the House of Medicine be able to assess their current and future workforce supply. This information has direct relevance to funding of graduate medical education. We describe a dynamic modeling tool that examines how individual factors and practice variables can be used to measure and forecast the supply and demand for existing and new physician services. The system we describe, while built to analyze the pathologist workforce, is sufficiently broad and robust for use in any medical specialty. Our design provides a computer-based software model populated with data from surveys and best estimates by specialty experts about current and new activities in the scope of practice. The model describes the steps needed and data required for analysis of supply and demand. Our modeling tool allows educators and policy makers, in addition to physician specialty organizations, to assess how various factors may affect demand (and supply) of current and emerging services. Examples of factors evaluated include types of professional services (3 categories with 16 subcategories), service locations, elements related to the Patient Protection and Affordable Care Act, new technologies, aging population, and changing roles in capitated, value-based, and team-based systems of care. The model also helps identify where physicians in a given specialty will likely need to assume new roles, develop new expertise, and become more efficient in practice to accommodate new value-based payment model
An Innovative Interactive Modeling Tool to Analyze Scenario-Based Physician Workforce Supply and Demand
Effective physician workforce management requires that the various organizations comprising the House of Medicine be able to assess their current and future workforce supply. This information has direct relevance to funding of graduate medical education. We describe a dynamic modeling tool that examines how individual factors and practice variables can be used to measure and forecast the supply and demand for existing and new physician services. The system we describe, while built to analyze the pathologist workforce, is sufficiently broad and robust for use in any medical specialty. Our design provides a computer-based software model populated with data from surveys and best estimates by specialty experts about current and new activities in the scope of practice. The model describes the steps needed and data required for analysis of supply and demand. Our modeling tool allows educators and policy makers, in addition to physician specialty organizations, to assess how various factors may affect demand (and supply) of current and emerging services. Examples of factors evaluated include types of professional services (3 categories with 16 subcategories), service locations, elements related to the Patient Protection and Affordable Care Act, new technologies, aging population, and changing roles in capitated, value-based, and team-based systems of care. The model also helps identify where physicians in a given specialty will likely need to assume new roles, develop new expertise, and become more efficient in practice to accommodate new value-based payment models
Nanometric moiré stripes on the surface of Bi2Se3 topological insulator
Mismatch between adjacent atomic layers in low-dimensional materials, generating moiré patterns, has recently emerged as a suitable method to tune electronic properties by inducing strong electron correlations and generating novel phenomena. Beyond graphene, van der Waals structures such as three-dimensional (3D) topological insulators (TIs) appear as ideal candidates for the study of these phenomena due to the weak coupling between layers. Here we discover and investigate the origin of 1D moiré stripes on the surface of Bi2Se3TI thin films and nanobelts. Scanning tunneling microscopy and high-resolution transmission electron microscopy reveal a unidirectional strained top layer, in the range 14-25%, with respect to the relaxed bulk structure, which cannot be ascribed to the mismatch with the substrate lattice but rather to strain induced by a specific growth mechanism. The 1D stripes are characterized by a spatial modulation of the local density of states, which is strongly enhanced compared to the bulk system. Density functional theory calculations confirm the experimental findings, showing that the TI surface Dirac cone is preserved in the 1D moiré stripes, as expected from the topology, though with a heavily renormalized Fermi velocity that also changes between the top and valley of the stripes. The strongly enhanced density of surface states in the TI 1D moiré superstructure can be instrumental in promoting strong correlations in the topological surface states, which can be responsible for surface magnetism and topological superconductivity
Pairing symmetry of superconducting graphene
The possibility of intrinsic superconductivity in alkali-coated graphene
monolayers has been recently suggested theoretically. Here, we derive the
possible pairing symmetries of a carbon honeycomb lattice and discuss their
phase diagram. We also evaluate the superconducting local density of states
(LDOS) around an isolated impurity. This is directly related to scanning
tunneling microscopy experiments, and may evidence the occurrence of
unconventional superconductivity in graphene.Comment: Eur. Phys. J. B, to appea
Ultrarelativistic electron-hole pairing in graphene bilayer
We consider ground state of electron-hole graphene bilayer composed of two
independently doped graphene layers when a condensate of spatially separated
electron-hole pairs is formed. In the weak coupling regime the pairing affects
only conduction band of electron-doped layer and valence band of hole-doped
layer, thus the ground state is similar to ordinary BCS condensate. At strong
coupling, an ultrarelativistic character of electron dynamics reveals and the
bands which are remote from Fermi surfaces (valence band of electron-doped
layer and conduction band of hole-doped layer) are also affected by the
pairing. The analysis of instability of unpaired state shows that s-wave
pairing with band-diagonal condensate structure, described by two gaps, is
preferable. A relative phase of the gaps is fixed, however at weak coupling
this fixation diminishes allowing gapped and soliton-like excitations. The
coupled self-consistent gap equations for these two gaps are solved at zero
temperature in the constant-gap approximation and in the approximation of
separable potential. It is shown that, if characteristic width of the pairing
region is of the order of magnitude of chemical potential, then the value of
the gap in the spectrum is not much different from the BCS estimation. However,
if the pairing region is wider, then the gap value can be much larger and
depends exponentially on its energy width.Comment: 13 pages with 8 figures; accepted to Eur. Phys. J.
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