Accumulation layer profiles at InAs polar surfaces

High resolution electron energy loss spectroscopy, dielectric theory simulations, and charge profile calculations have been used to study the accumulation layer and surface plasmon excitations at the In-terminated (001)-(4 × 1) and (111)A-(2 × 2) surfaces of InAs. For the (001) surface, the surface state density is 4.0 ± 2.0 × 1011 cm – 2, while for the (111)A surface it is 7.5 ± 2.0 × 1011 cm – 2, these values being independent of the surface preparation procedure, bulk doping level, and substrate temperature. Changes of the bulk Fermi level with temperature and bulk doping level do, however, alter the position of the surface Fermi level. Ion bombardment and annealing of the surface affect the accumulation layer only through changes in the effective bulk doping level and the bulk momentum scattering rate, with no discernible changes in the surface charge density

Electronic Selection Rules Controlling Dislocation Glide in bcc Metals

The validity of the structure-property relationships governing the deformation behavior of bcc metals was brought into question with recent {\it ab initio} density functional studies of isolated screw dislocations in Mo and Ta. These existing relationships were semiclassical in nature, having grown from atomistic investigations of the deformation properties of the groups V and VI transition metals. We find that the correct form for these structure-property relationships is fully quantum mechanical, involving the coupling of electronic states with the strain field at the core of long $a/2$ screw dislocations.Comment: 4 pages, 2 figure

Photonic Quantum Logic with Narrowband Light from Single Atoms

Increasing control of single photons enables new applications of photonic quantum-enhanced technology and further experimental exploration of fundamental quantum phenomena. Here, we demonstrate quantum logic using narrow linewidth photons that are produced under nearly perfect quantum control from a single ^87Rb atom strongly coupled to a high-finesse cavity. We use a controlled- NOT gate integrated into a photonic chip to entangle these photons, and we observe non-classical correlations between events separated by periods exceeding the travel time across the chip by three orders of magnitude. This enables quantum technology that will use the properties of both narrowband single photon sources and integrated quantum photonics, such as networked quantum computing, narrow linewidth quantum enhanced sensing and atomic memories.Comment: 5 pates, 3 figure

PRIDE: a public repository of protein and peptide identifications for the proteomics community

PRIDE, the ‘PRoteomics IDEntifications database’ () is a database of protein and peptide identifications that have been described in the scientific literature. These identifications will typically be from specific species, tissues and sub-cellular locations, perhaps under specific disease conditions. Any post-translational modifications that have been identified on individual peptides can be described. These identifications may be annotated with supporting mass spectra. At the time of writing, PRIDE includes the full set of identifications as submitted by individual laboratories participating in the HUPO Plasma Proteome Project and a profile of the human platelet proteome submitted by the University of Ghent in Belgium. By late 2005 PRIDE is expected to contain the identifications and spectra generated by the HUPO Brain Proteome Project. Proteomics laboratories are encouraged to submit their identifications and spectra to PRIDE to support their manuscript submissions to proteomics journals. Data can be submitted in PRIDE XML format if identifications are included or mzData format if the submitter is depositing mass spectra without identifications. PRIDE is a web application, so submission, searching and data retrieval can all be performed using an internet browser. PRIDE can be searched by experiment accession number, protein accession number, literature reference and sample parameters including species, tissue, sub-cellular location and disease state. Data can be retrieved as machine-readable PRIDE or mzData XML (the latter for mass spectra without identifications), or as human-readable HTML

Remotely sensing the morphometrics and dynamics of a cold region dune field using historical aerial photography and airborne LIDAR data

© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Remote Sensing 10 (2018): 792, doi:10.3390/rs10050792.This study uses an airborne Light Detection and Ranging (LiDAR) survey, historical aerial photography and historical climate data to describe the character and dynamics of the Nogahabara Sand Dunes, a sub-Arctic dune field in interior Alaska’s discontinuous permafrost zone. The Nogahabara Sand Dunes consist of a 43-km2 area of active transverse and barchanoid dunes within a 3200-km2 area of vegetated dune and sand sheet deposits. The average dune height in the active portion of the dune field is 5.8 m, with a maximum dune height of 28 m. Dune spacing is variable with average crest-to-crest distances for select transects ranging from 66–132 m. Between 1952 and 2015, dunes migrated at an average rate of 0.52 m a−1. Dune movement was greatest between 1952 and 1978 (0.68 m a−1) and least between 1978 and 2015 (0.43 m a−1). Dunes migrated predominantly to the southeast; however, along the dune field margin, net migration was towards the edge of the dune field regardless of heading. Better constraining the processes controlling dune field dynamics at the Nogahabara dunes would provide information that can be used to model possible reactivation of more northerly dune fields and sand sheets in response to climate change, shifting fire regimes and permafrost thaw.Funding for this research was provided by the U.S. Geological Survey Land Change Science and Land Remote Sensing programs, the U.S. Fish andWildlife Service and the University of Alaska Fairbanks

Deep Imaging of AXJ2019+112: The Luminosity of a ``Dark Cluster''

We detect a distant cluster of galaxies centered on the QSO lens and luminous X-ray source AXJ2019+112, a.k.a. ``The Dark Cluster'' (Hattori et al 1997). Using deep V,I Keck images and wide-field K_s imaging from the NTT, a tight red sequence of galaxies is identified within a radius of 0.2 h^{-1} Mpc of the known z=1.01 elliptical lensing galaxy. The sequence, which includes the central elliptical galaxy, has a slope in good agreement with the model predictions of Kodama et al (1998) for z~1. We estimate the integrated rest-frame luminosity of the cluster to be L_V > 3.2 x 10^{11}h^{-2}L_{\sun} (after accounting for significant extinction at the low latitude of this field), more than an order of magnitude higher than previous estimates. The central region of the cluster is deconvolved using the technique of Magain, Courbin & Sohy (1998), revealing a thick central arc coincident with an extended radio source. All the observed lensing features are readily explained by differential magnification of a radio loud AGN by a shallow elliptical potential. The QSO must lie just outside the diamond caustic, producing two images, and the arc is a highly magnified image formed from a region close to the center of the host galaxy, projecting inside the caustic. The mass--to--light ratio within an aperture of 0.4 h ^{-1} Mpc is M_x/L_V= 224^{+112}_{-78}h(M/L_V)_{\sun}, using the X-ray temperature. The strong lens model yields a compatible value, M/L_V= 372^{+94}_{-94}h(M/L_V)_{\sun}, whereas an independent weak lensing analysis sets an upper limit of M/L_V <520 h(M/L_V)_{\sun}, typical of massive clusters.Comment: AAS Latex format, 24 pages, 9 figures. Fig 1a,b available at http://astro.berkeley.edu/~benitezn/cluster.html . Submitted to ApJ on August 15t

On the Double Planet System Around HD 83443

The Geneva group has reported two Saturn-mass planets orbiting HD 83443 (K0V) with periods of 2.98 and 29.8 d. The two planets have raised interest in their dynamics because of the possible 10:1 orbital resonance and the strong gravitational interactions. We report precise Doppler measurements of HD 83443 obtained with the Keck/HIRES and the AAT/UCLES spectrometers. These measurements strongly confirm the inner planet with period of 2.985 d, with orbital parameters in very good agreement with those of the Geneva group. However these Doppler measurements show no evidence of the outer planet, at thresholds of 1/4 (3 m/s) of the reported velocity amplitude of 13.8 m/s. Thus, the existence of the outer planet is in question. Indeed, the current Doppler measurements reveal no evidence of any second planet with periods less than a year.Comment: 26 pages incl. 3 tables and 8 figures; uses AASTE

Patient and public involvement to inform priorities and practice for research using existing healthcare data for children’s and young people’s cancers

Background: In the United Kingdom, healthcare data is collected on all patients receiving National Health Service (NHS) care, including children and young people (CYP) with cancer. This data is used to inform service delivery, and with special permissions used for research. The use of routinely collected health data in research is an advancing field with huge potential benefit, particularly in CYP with cancer where case numbers are small and the impact across the life course can be significant. Patient and public involvement (PPI) exercise aims: Identify current barriers to trust relating to the use of healthcare data for research. Determine ways to increase public and patient confidence in the use of healthcare data in research. Define areas of research importance to CYP and their carers using healthcare data. // Methods: Young people currently aged between 16 and 25 years who had a cancer diagnosis before the age of 20 years and carers of a young person with cancer were invited to take part via social media and existing networks of service users. Data was collected during two interactive online workshops totalling 5 h and comprising of presentations from health data experts, case-studies and group discussions. With participant consent the workshops were recorded, transcribed verbatim and analysed using thematic analysis. // Results: Ten young people and six carers attended workshop one. Four young people and four carers returned for workshop two. Lack of awareness of how data is used, and negative media reporting were seen as the main causes of mistrust. Better communication and education on how data is used were felt to be important to improving public confidence. Participants want the ability to have control over their own data use. Late effects, social and education outcomes and research on rare tumours were described as key research priorities for data use. // Conclusions: In order to improve public and patient trust in our use of data for research, we need to improve communication about how data is used and the benefits that arise

Contrasting vulnerability of drained tropical and high-latitude peatlands to fluvial loss of stored carbon

Carbon sequestration and storage in peatlands rely on consistently highwater tables. Anthropogenic pressures including drainage, burning, land conversion for agriculture, timber, and biofuel production, cause loss of peat-forming vegetation and exposure of previously anaerobic peat to aerobic decomposition. This can shift peatlands from net CO2 sinks to large CO2 sources, releasing carbon held for millennia. Peatlands also export significant quantities of carbon via fluvial pathways, mainly as dissolved organic carbon (DOC). We analyzed radiocarbon (14C) levels of DOC in drainage water from multiple peatlands in Europe and Southeast Asia, to infer differences in the age of carbon lost from intact and drained systems. In most cases, drainage led to increased release of older carbon from the peat profile but withmarked differences related to peat type. Very low DOC-14C levels in runoff from drained tropical peatlands indicate loss of very old (centuries to millennia) stored peat carbon. High-latitude peatlands appear more resilient to drainage; 14C measurements from UK blanket bogs suggest that exported DOC remains young (500 year) carbon in high-latitude systems. Rewetting at least partially offsets drainage effects on DOC age