128,686 research outputs found
Spin-dependent Fano resonance induced by conducting chiral helimagnet contained in a quasi-one-dimensional electron waveguide
Fano resonance appears for conduction through an electron waveguide
containing donor impurities. In this work, we consider the thin-film conducting
chiral helimagnet (CCH) as the donor impurity in a one-dimensional waveguide
model. Due to the spin spiral coupling, interference between the direct and
intersubband transmission channels gives rise to spin-dependent Fano resonance
effect. The spin-dependent Fano resonance is sensitively dependent on the
helicity of the spiral. By tuning the CCH potential well depth and the incident
energy, this provides a potential way to detect the spin structure in the CCH.Comment: 14 pages, 6 figure
On the spectral distribution of kernel matrices related to\ud radial basis functions
This paper focuses on the spectral distribution of kernel matrices related to radial basis functions. The asymptotic behaviour of eigenvalues of kernel matrices related to radial basis functions with different smoothness are studied. These results are obtained by estimated the coefficients of an orthogonal expansion of the underlying kernel function. Beside many other results, we prove that there are exactly (k+d−1/d-1) eigenvalues in the same order for analytic separable kernel functions like the Gaussian in Rd. This gives theoretical support for how to choose the diagonal scaling matrix in the RBF-QR method (Fornberg et al, SIAM J. Sci. Comput. (33), 2011) which can stably compute Gaussian radial basis function interpolants
Vibrating Superconducting Island in a Josephson Junction
We consider a combined nanomechanical-supercondcuting device that allows the
Cooper pair tunneling to interfere with the mechanical motion of the middle
superconducting island. Coupling of mechanical oscillations of a
superconducting island between two superconducting leads to the electronic
tunneling generate a supercurrent which is modulated by the oscillatory motion
of the island. This coupling produces alternating finite and vanishing
supercurrent as function of the superconducting phases. Current peaks are
sensitive to the superconducting phase shifts relative to each other. The
proposed device may be used to study the nanoelectromechanical coupling in case
of superconducting electronics.Comment: 4 pages, 3 figures, to appear in Phys. Rev. Let
Quantum interference in nested d-wave superconductors: a real-space perspective
We study the local density of states around potential scatterers in d-wave
superconductors, and show that quantum interference between impurity states is
not negligible for experimentally relevant impurity concentrations. The two
impurity model is used as a paradigm to understand these effects analytically
and in interpreting numerical solutions of the Bogoliubov-de Gennes equations
on fully disordered systems. We focus primarily on the globally particle-hole
symmetric model which has been the subject of considerable controversy, and
give evidence that a zero-energy delta function exists in the DOS. The
anomalous spectral weight at zero energy is seen to arise from resonant
impurity states belonging to a particular sublattice, exactly as in the
2-impurity version of this model. We discuss the implications of these findings
for realistic models of the cuprates.Comment: 12 pages, 10 figs, submitted to Phys. Rev.
Two impurities in a d-wave superconductor:local density of states
We study the problem of two local potential scatterers in a d-wave
superconductor, and show how quasiparticle bound state wave functions
interfere. Each single-impurity electron and hole resonance energy is in
general split in the presence of a second impurity into two, corresponding to
one even parity and one odd parity state. We calculate the local density of
states (LDOS), and argue that scanning tunneling microscopy (STM) measurements
should be capable of extracting information about the Green's function in the
pure system by a systematic study of 2-impurity configurations. In some
configurations highly localized, long-lived states are predicted. We discuss
the effects of realistic band structures, and how 2-impurity STM measurements
could help distinguish between current explanations of LDOS impurity spectra in
the BSCCO-2212 system.Comment: 16 pages,21 figure,New Version to be Published on P.R.
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Strengthening strategic management approaches to address antimicrobial resistance in global human health: a scoping review
Introduction
The development and implementation of national strategic plans is a critical component towards successfully addressing antimicrobial resistance (AMR). This study aimed to review the scope and analytical depth of situation analyses conducted to address AMR in human health to inform the development and implementation of national strategic plans.
Methods
A systematic search of the literature was conducted to identify all studies since 2000, that have employed a situation analysis to address AMR. The included studies are analysed against frameworks for strategic analysis, primarily the PESTELI (Political, Economic, Sociological, Technological, Ecological, Legislative, Industry) framework, to understand the depth, scope and utility of current published approaches.
Results
10 studies were included in the final review ranging from single country (6) to regional-level multicountry studies (4). 8 studies carried out documentary review, and 3 of these also included stakeholder interviews. 2 studies were based on expert opinion with no data collection. No study employed the PESTELI framework. Most studies (9) included analysis of the political domain and 1 study included 6 domains of the framework. Technological and industry analyses is a notable gap. Facilitators and inhibitors within the political and legislative domains were the most frequently reported. No facilitators were reported in the economic or industry domains but featured inhibiting factors including: lack of ring-fenced funding for surveillance, perverse financial incentives, cost-shifting to patients; joint-stock drug company ownership complicating regulations.
Conclusion
The PESTELI framework provides further opportunities to combat AMR using a systematic, strategic management approach, rather than a retrospective view. Future analysis of existing quantitative data with interviews of key strategic and operational stakeholders is needed to provide critical insights about where implementation efforts should be focussed, and also how to build contingency at the strategic level for agile responses to macro-level environmental influences
Frequency comb vernier spectroscopy in the near infrared
We perform femtosecond frequency comb vernier spectroscopy in the near
infrared with a femtosecond Er doped fiber laser, a scanning high-finesse
cavity and an InGaAs camera. By utilizing the properties of a frequency comb
and a scanning high-finesse cavity such spectroscopy provides broad spectral
bandwidth, high spectral resolution, and high detection sensitivity on a short
time scale. We achieved an absorption sensitivity of ~8E-8 cm-1Hz-1/2
corresponding to a detection limit of ~70 ppbv for acetylene, with a resolution
of ~1.1 GHz in single images taken in 0.5 seconds and covering a frequency
range of ~5 THz. These measurements have broad applications for sensing other
greenhouse gases in this fingerprint near IR region with a simple apparatus.Comment: 14 pages, 5 figure
Controlling the superconducting transition by spin-orbit coupling
Whereas there exists considerable evidence for the conversion of singlet
Cooper pairs into triplet Cooper pairs in the presence of inhomogeneous
magnetic fields, recent theoretical proposals have suggested an alternative way
to exert control over triplet generation: intrinsic spin-orbit coupling in a
homogeneous ferromagnet coupled to a superconductor. Here, we proximity-couple
Nb to an asymmetric Pt/Co/Pt trilayer, which acts as an effective spin-orbit
coupled ferromagnet owing to structural inversion asymmetry. Unconventional
modulation of the superconducting critical temperature as a function of
in-plane and out-of- plane applied magnetic fields suggests the presence of
triplets that can be controlled by the magnetic orientation of a single
homogeneous ferromagnet. Our studies demonstrate for the first time an active
role of spin-orbit coupling in controlling the triplets -- an important step
towards the realization of novel superconducting spintronic devices.Comment: 11 pages + 4 figures + supplemental informatio
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