308 research outputs found
R-matrix Floquet theory for laser-assisted electron-atom scattering
A new version of the R-matrix Floquet theory for laser-assisted electron-atom
scattering is presented. The theory is non-perturbative and applicable to a
non-relativistic many-electron atom or ion in a homogeneous linearly polarized
field. It is based on the use of channel functions built from field-dressed
target states, which greatly simplifies the general formalism.Comment: 18 pages, LaTeX2e, submitted to J.Phys.
The Scottish clinical supervision model for midwives
Following a change in UK legislation, the Nursing and Midwifery Council (NMC) model of statutory supervision for midwives ceased in 2017. In response, the Scottish Government (SG) and NHS Education for Scotland (NES) worked with the NHS Health Boards to develop a new employer-led model of clinical supervision. The aim of this new model is to help midwives provide improved services, safer care and improved outcomes for childbearing women and infants in keeping with professional regulation. The new Scottish Clinical Supervision Model is also designed to increase midwives personal wellbeing and help them deal with everyday challenges of clinical practice. This design of supervision is a radical departure from the prior NMC model, given that it incorporates facilitation and coaching methods which teach midwives to respond, reflect, and restore self, and through doing so reduce stress and increase resilience. In an attempt to improve nurturing leadership, the key components of this new model are underpinned by a person-centred approach, during which the supervisor provides unconditional positive regard and empathy towards the supervisee. Equipping midwives to develop contemporary supervision is supported by NES through online education that can be accessed at: https://www.nes.scot.nhs.uk/education-and-training/by-theme-initiative/maternity-care/about-us/clinical-supervision.asp
Snowmass Neutrino Frontier: Neutrino Interaction Cross Sections (NF06) Topical Group Report
A thorough understanding of neutrino cross sections in a wide range of
energies is crucial for the successful execution of the entire neutrino physics
program. In order to extract neutrino properties, long-baseline experiments
need an accurate determination of neutrino cross sections within their
detector(s). Since very few of the needed neutrino cross sections across the
energy spectrum are directly measured, we emphasize the need for theoretical
input and indirect measurements such as electron scattering, which would
complement direct measurements. In this report we briefly summarize the current
status of our knowledge of the neutrino cross sections and articulate needs of
the experiments, ongoing and planned, at energies ranging from CEvNS and
supernova neutrino energies to the DUNE and atmospheric neutrino energies.Comment: 38 pages, 1 figur
The transition from the adiabatic to the sudden limit in core level photoemission: A model study of a localized system
We consider core electron photoemission in a localized system, where there is
a charge transfer excitation. The system is modelled by three electron levels,
one core level and two outer levels. The model has a Coulomb interaction
between these levels and the continuum states into which the core electron is
emitted. The model is simple enough to allow an exact numerical solution, and
with a separable potential an analytic solution. We calculate the ratio
r(omega) between the weights of the satellite and the main peak as a function
of the photon energy omega. The transition from the adiabatic to the sudden
limit takes place for quite small photoelectron kinetic energies. For such
small energies, the variation of the dipole matrix element is substantial and
described by the energy scale Ed. Without the coupling to the photoelectron,
the corresponding ratio r0(omega) is determined by Ed and the satellite
excitation energy dE. When the interaction potential with the continuum states
is introduced, a new energy scale Es=1/(2Rs^2) enters, where Rs is a length
scale of the interaction potential. At threshold there is typically a (weak)
constructive interference between intrinsic and extrinsic contributions, and
the ratio r(omega)/r0(omega) is larger than its limiting value for large omega.
The interference becomes small or weakly destructive for photoelectron energies
of the order Es. For larger energies r(omega)/r0(omega) therefore typically has
a weak undershoot. If this undershoot is neglected, r(omega)/r0(omega) reaches
its limiting value on the energy scale Es.Comment: 18 pages, latex2e, 13 eps figure
Electron quantum metamaterials in van der Waals heterostructures
In recent decades, scientists have developed the means to engineer synthetic
periodic arrays with feature sizes below the wavelength of light. When such
features are appropriately structured, electromagnetic radiation can be
manipulated in unusual ways, resulting in optical metamaterials whose function
is directly controlled through nanoscale structure. Nature, too, has adopted
such techniques -- for example in the unique coloring of butterfly wings -- to
manipulate photons as they propagate through nanoscale periodic assemblies. In
this Perspective, we highlight the intriguing potential of designer
sub-electron wavelength (as well as wavelength-scale) structuring of electronic
matter, which affords a new range of synthetic quantum metamaterials with
unconventional responses. Driven by experimental developments in stacking
atomically layered heterostructures -- e.g., mechanical pick-up/transfer
assembly -- atomic scale registrations and structures can be readily tuned over
distances smaller than characteristic electronic length-scales (such as
electron wavelength, screening length, and electron mean free path). Yet
electronic metamaterials promise far richer categories of behavior than those
found in conventional optical metamaterial technologies. This is because unlike
photons that scarcely interact with each other, electrons in subwavelength
structured metamaterials are charged, and strongly interact. As a result, an
enormous variety of emergent phenomena can be expected, and radically new
classes of interacting quantum metamaterials designed
Large tunable valley splitting in edge-free graphene quantum dots on boron nitride
Coherent manipulation of binary degrees of freedom is at the heart of modern
quantum technologies. Graphene offers two binary degrees: the electron spin and
the valley. Efficient spin control has been demonstrated in many solid state
systems, while exploitation of the valley has only recently been started, yet
without control on the single electron level. Here, we show that van-der Waals
stacking of graphene onto hexagonal boron nitride offers a natural platform for
valley control. We use a graphene quantum dot induced by the tip of a scanning
tunneling microscope and demonstrate valley splitting that is tunable from -5
to +10 meV (including valley inversion) by sub-10-nm displacements of the
quantum dot position. This boosts the range of controlled valley splitting by
about one order of magnitude. The tunable inversion of spin and valley states
should enable coherent superposition of these degrees of freedom as a first
step towards graphene-based qubits
The diversification of Heliconius butterflies: what have we learned in 150 years?
Research into Heliconius butterflies has made a significant contribution to evolutionary biology. Here, we review our understanding of the diversification of these butterflies, covering recent advances and a vast foundation of earlier work. Whereas no single group of organisms can be sufficient for understanding life's diversity, after years of intensive study, research into Heliconius has addressed a wide variety of evolutionary questions. We first discuss evidence for widespread gene flow between Heliconius species and what this reveals about the nature of species. We then address the evolution and diversity of warning patterns, both as the target of selection and with respect to their underlying genetic basis. The identification of major genes involved in mimetic shifts, and homology at these loci between distantly related taxa, has revealed a surprising predictability in the genetic basis of evolution. In the final sections, we consider the evolution of warning patterns, and Heliconius diversity more generally, within a broader context of ecological and sexual selection. We consider how different traits and modes of selection can interact and influence the evolution of reproductive isolation.RMM is funded by a Junior Research Fellowship at King’s College, Cambridge. KMK is supported by the Balfour Studentship, University of Cambridge, SHMa by a Research Fellowship at St John's College, Cambridge, and SHMo by a Research Fellowship from the Royal Commission for the Exhibition of 1851. Our work on Heliconius has been additionally supported by the Agence Nationale de la Recherche (France), the Biology and Biotechnology Research Council (UK), the British Ecological Society, the European Research Council, the Natural Environment Research Council (UK), and the Smithsonian Tropical Research Institute.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1111/jeb.1267
Long-Baseline Neutrino Facility (LBNF) and Deep Underground Neutrino Experiment (DUNE) Conceptual Design Report Volume 2: The Physics Program for DUNE at LBNF
The Physics Program for the Deep Underground Neutrino Experiment (DUNE) at
the Fermilab Long-Baseline Neutrino Facility (LBNF) is described
On Switch-Reference Phenomena in Kolyma Yukaghir
「環太平洋の言語」成果報告書A2-002ELPR publication series A2-00
Search for short baseline nu(e) disappearance with the T2K near detector
8 pages, 6 figures, submitted to PRD rapid communication8 pages, 6 figures, submitted to PRD rapid communicationWe thank the J-PARC staff for superb accelerator performance and the CERN NA61 collaboration for providing valuable particle production data. We acknowledge the support of MEXT, Japan; NSERC, NRC and CFI, Canada; Commissariat `a l’Energie Atomique and Centre National de la Recherche Scientifique–Institut National de Physique Nucle´aire et de Physique des Particules, France; DFG, Germany; INFN, Italy; National Science Centre (NCN), Poland; Russian Science Foundation, RFBR and Ministry of Education and Science, Russia; MINECO and European Regional Development Fund, Spain; Swiss National Science Foundation and State Secretariat for Education, Research and Innovation, Switzerland; STFC, UK; and DOE, USA. We also thank CERN for the UA1/NOMAD magnet, DESY for the HERA-B magnet mover system, NII for SINET4, the WestGrid and SciNet consortia in Compute Canada, GridPP, UK. In addition participation of individual researchers and institutions has been further supported by funds from ERC (FP7), EU; JSPS, Japan; Royal Society, UK; DOE Early Career program, USA
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