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Languages and Learning at Key Stage 2: A Longitudinal Study Final Report
In 2006, The Open University, the University of Southampton and Canterbury Christ Church University were commissioned by the then Department for Education and Skills (DfES), now Department for Children, Schools and Families (DCSF) to conduct a three-year longitudinal study of languages learning at Key Stage 2 (KS2). The qualitative study was designed to explore provision, practice and developments over three school years between 2006/07 and 2008/09 in a sample of primary schools and explore children’s achievement in oracy and literacy, as well as the possible broader cross-curricular impact of languages learning
Two-Spinon and Orbital Excitations of the Spin-Peierls System TiOCl
We combine high-resolution resonant inelastic x-ray scattering with cluster
calculations utilizing a recently derived effective magnetic scattering
operator to analyze the polarization, excitation energy, and momentum dependent
excitation spectrum of the low-dimensional quantum magnet TiOCl in the range
expected for orbital and magnetic excitations (0 - 2.5 eV). Ti 3d orbital
excitations yield complete information on the temperature-dependent
crystal-field splitting. In the spin-Peierls phase we observe a dispersive
two-spinon excitation and estimate the inter- and intra-dimer magnetic exchange
coupling from a comparison to cluster calculations
Are the renormalized band widths in TTF-TCNQ of structural or electronic origin? - An angular dependent NEXAFS study
We have performed angle-dependent near-edge x-ray absorption fine structure
measurements in the Auger electron yield mode on the correlated
quasi-one-dimensional organic conductor TTF-TCNQ in order to determine the
orientation of the molecules in the topmost surface layer. We find that the
tilt angles of the molecules with respect to the one-dimensional axis are
essentially the same as in the bulk. Thus we can rule out surface relaxation as
the origin of the renormalized band widths which were inferred from the
analysis of photoemission data within the one-dimensional Hubbard model.
Thereby recent theoretical results are corroborated which invoke long-range
Coulomb repulsion as alternative explanation to understand the spectral
dispersions of TTF-TCNQ quantitatively within an extended Hubbard model.Comment: 6 pages, 5 figure
Direct k-space mapping of the electronic structure in an oxide-oxide interface
The interface between LaAlO3 and SrTiO3 hosts a two-dimensional electron
system of itinerant carriers, although both oxides are band insulators.
Interface ferromagnetism coexisting with superconductivity has been found and
attributed to local moments. Experimentally, it has been established that Ti 3d
electrons are confined to the interface. Using soft x-ray angle-resolved
resonant photoelectron spectroscopy we have directly mapped the interface
states in k-space. Our data demonstrate a charge dichotomy. A mobile fraction
contributes to Fermi surface sheets, whereas a localized portion at higher
binding energies is tentatively attributed to electrons trapped by O-vacancies
in the SrTiO3. While photovoltage effects in the polar LaAlO3 layers cannot be
excluded, the apparent absence of surface-related Fermi surface sheets could
also be fully reconciled in a recently proposed electronic reconstruction
picture where the built-in potential in the LaAlO3 is compensated by surface
O-vacancies serving also as charge reservoir.Comment: 8 pages, 6 figures, incl. Supplemental Informatio
Circular dichroism and bilayer splitting in the normal state of underdoped (Pb,Bi)Sr(CaY)CuO and overdoped (Pb,Bi)SrCaCuO
We report an ARPES investigation of the circular dichroism in the first
Brillouin zone (BZ) of under- and overdoped Pb-Bi2212 samples. We show that the
dichroism has opposite signs for bonding and antibonding components of the
bilayer-split CuO-band and is antisymmetric with respect to reflections in both
mirror planes parallel to the c-axis. Using this property of the energy and
momentum intensity distributions we prove the existence of the bilayer
splitting in the normal state of the underdoped compound and compare its value
with the splitting in overdoped sample. In agreement with previous studies the
magnitude of the interlayer coupling does not depend significantly on doping.
We also discuss possible origins of the observed dichroism.Comment: 4 RevTex pages, 4 EPS figure
The atmospheric circulation of a nine-hot Jupiter sample: probing circulation and chemistry over a wide phase space
This is the author accepted manuscript. The final version is available from the American Astronomical Society / IOP Publishing via the DOI in this record.We present results from an atmospheric circulation study of nine hot Jupiters that comprise a large transmission spectral survey using the Hubble and Spitzer Space Telescopes. These observations exhibit a range of spectral behavior over optical and infrared wavelengths which suggest diverse cloud and haze properties in their atmospheres. By utilizing the speci c system parameters for each planet, we naturally probe a wide phase space in planet radius, gravity, orbital period, and equilibrium temperature. First, we show that our model \grid" recovers trends shown in traditional parametric studies of hot Jupiters, particularly equatorial superrotation and increased day-night temperature contrast with increasing equilibrium temperature. We show how spatial temperature variations, particularly between the dayside and nightside and west and east terminators, can vary by hundreds of K, which could imply large variations in Na, K, CO and CH4 abundances in those regions. These chemical variations can be large enough to be observed in transmission with high-resolution spectrographs, such as ESPRESSO on VLT, METIS on the E-ELT, or with MIRI and NIRSpec aboard JWST. We also compare theoretical emission spectra generated from our models to available Spitzer eclipse depths for each planet, and nd that the outputs from our solar-metallicity, cloud-free models generally provide a good match to many of the datasets, even without additional model tuning. Although these models are cloud-free, we can use their results to understand the chemistry and dynamics that drive cloud formation in their atmospheres.European Research Council under the European Unions Seventh Framework Program (FP7/2007-2013)NAS
Time-lapse ultrashort pulse microscopy of infection in three-dimensional versus two-dimensional culture environments reveals enhanced extra-chromosomal virus replication compartment formation
The mechanisms that enable viruses to harness cellular machinery for their own survival are primarily studied in cell lines cultured in two-dimensional (2-D) environments. However, there are increasing reports of biological differences between cells cultured in 2-D versus three-dimensional (3-D) environments. Here we report differences in host-virus interactions based on differences in culture environment. Using ultrashort pulse microscopy (UPM), a form of two-photon microscopy that utilizes sub-10-fs pulses to efficiently excite fluorophores, we have shown that de novo development of extra-chromosomal virus replication compartments (VRCs) upon murine cytomegalovirus (mCMV) infection is markedly enhanced when host cells are cultured in 3-D collagen gels versus 2-D monolayers. In addition, time-lapse imaging revealed that mCMV-induced VRCs have the capacity to grow by coalescence. This work supports the future potential of 3-D culture as a useful bridge between traditional monolayer cultures and animal models to study host-virus interactions in a more physiologically relevant environment for the development of effective anti-viral therapeutics. These advances will require broader adoption of modalities, such as UPM, to image deep within scattering tissues
Searching for Far-Ultraviolet Auroral/Dayglow Emission from HD209458b
We present recent observations from the HST-Cosmic Origins Spectrograph aimed
at characterizing the auroral emission from the extrasolar planet HD209458b. We
obtained medium-resolution (R~18-20,000) far-ultraviolet (1150-1700A) spectra
at both the Phase 0.25 and Phase 0.75 quadrature positions as well as a stellar
baseline measurement at secondary eclipse. This analysis includes a catalog of
stellar emission lines and a star-subtracted spectrum of the planet. We present
an emission model for planetary H2 emission, and compare this model to the
planetary spectrum. No unambiguously identifiable atomic or molecular features
are detected, and upper limits are presented for auroral/dayglow line
strengths. An orbital velocity cross-correlation analysis finds a statistically
significant (3.8 sigma) feature at +15 (+/- 20) km/s in the rest frame of the
planet, at 1582 A. This feature is consistent with emission from H2 B-X (2-9)
P(4) (lambda_{rest} = 1581.11 A), however the physical mechanism required to
excite this transition is unclear. We compare limits on relative line strengths
seen in the exoplanet spectrum with models of ultraviolet fluorescence to
constrain the atmospheric column density of neutral hydrogen between the star
and the planetary surface. These results support models of short period
extrasolar giant planets with weak magnetic fields and extended atomic
atmospheres.Comment: Accepted to ApJ. 12 pages, 5 figures, 4 table
Image Restoration by Matching Gradient Distributions
The restoration of a blurry or noisy image is commonly performed with a MAP estimator, which maximizes a posterior probability to reconstruct a clean image from a degraded image. A MAP estimator, when used with a sparse gradient image prior, reconstructs piecewise smooth images and typically removes textures that are important for visual realism. We present an alternative deconvolution method called iterative distribution reweighting (IDR) which imposes a global constraint on gradients so that a reconstructed image should have a gradient distribution similar to a reference distribution. In natural images, a reference distribution not only varies from one image to another, but also within an image depending on texture. We estimate a reference distribution directly from an input image for each texture segment. Our algorithm is able to restore rich mid-frequency textures. A large-scale user study supports the conclusion that our algorithm improves the visual realism of reconstructed images compared to those of MAP estimators
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