45,972 research outputs found
Correlation of p-doping in CVD Graphene with Substrate Surface Charges
Correlations between the level of p-doping exhibited in large area chemical vapour deposition (CVD) graphene field effect transistor structures (gFETs) and residual charges created by a variety of surface treatments to the silicon dioxide (SiO(2)) substrates prior to CVD graphene transfer are measured. Beginning with graphene on untreated thermal oxidised silicon, a minimum conductivity (Ï(min)) occurring at gate voltage V(g)â=â15âV (Dirac Point) is measured. It was found that more aggressive treatments (O(2) plasma and UV Ozone treatments) further increase the gate voltage of the Dirac point up to 65âV, corresponding to a significant increase of the level of p-doping displayed in the graphene. An electrowetting model describing the measured relationship between the contact angle (Ξ) of a water droplet applied to the treated substrate/graphene surface and an effective gate voltage from a surface charge density is proposed to describe biasing of V(g) at Ï(min) and was found to fit the measurements with multiplication of a correction factor, allowing effective non-destructive approximation of substrate added charge carrier density using contact angle measurements
13CO at the centre of M82
Using the IRAM interferometer, we have observed the nearby starburst galaxy
M82 with a 4.2" resolution (~70 pc) in the 1->0 line of 13CO and in the 2.6-mm
continuum.
The spatial distribution of the 13CO line shows the same gross features as
the 12CO(1->0) map of Shen & Lo (1995), namely two lobes and a compact central
source, though with different relative intensities. The lobes are more
conspicuous and the central source is fainter in 13CO than in 12CO.
The velocity field observed around the nucleus shows a very steep gradient
(140 km/s over 75 pc), which is very probably caused by the stellar bar visible
in the near infrared. The dynamical centre coincides with the IR peak and is
shifted 6" north-east of the compact 13CO source. The two CO lobes appear to be
associated with the ends of the bar and not with a molecular ring, as usually
assumed. They are probably shaped by the strong UV radiation from the central
region. 13CO must be more photodissociated than the self-shielded 12CO
molecules in the central ~250 pc region, which may explain the relative
weakness of the 13CO central source.
A 130 pc-wide bubble of molecular gas has been identified, which happens to
host the most luminous compact radio source in M82. It lies 120 pc west of the
IR peak between the central source and the western lobe and seems characterized
by warmer gas, strong UV radio free-free radiation, and an enhanced cosmic ray
production rate.Comment: Accepted by A&A; 9 pages, 9 ps figures, needs LaTeX 2e A&A macro and
psfig Styl
English economic growth, 1270-1700
We provide annual estimates of GDP for England over the period 1270-1700,
constructed from the output side. The GDP data are combined with population estimates
to calculate GDP per capita. Sectoral price data and estimates of nominal GDP are also
provided. We find per capita income growth of 0.20 per cent per annum, although growth
was episodic, with the strongest growth after the Black Death and in the second half of
the seventeenth century. Living standards in the late medieval period were well above
âbare bones subsistenceâ, although levels of kilocalorie consumption per head were
modest because of the very large share of pastoral production in agriculture
Near-Optimal Distributed Approximation of Minimum-Weight Connected Dominating Set
This paper presents a near-optimal distributed approximation algorithm for
the minimum-weight connected dominating set (MCDS) problem. The presented
algorithm finds an approximation in rounds,
where is the network diameter and is the number of nodes.
MCDS is a classical NP-hard problem and the achieved approximation factor
is known to be optimal up to a constant factor, unless P=NP.
Furthermore, the round complexity is known to be
optimal modulo logarithmic factors (for any approximation), following [Das
Sarma et al.---STOC'11].Comment: An extended abstract version of this result appears in the
proceedings of 41st International Colloquium on Automata, Languages, and
Programming (ICALP 2014
British economic growth : 1270 - 1870
We provide annual estimates of GDP for England between 1270 and 1700 and
for Great Britain between 1700 and 1870, constructed from the output side. The GDP
data are combined with population estimates to calculate GDP per capita. We find
English per capita income growth of 0.20 per cent per annum between 1270 and 1700,
although growth was episodic, with the strongest growth during the Black Death crisis of
the fourteenth century and in the second half of the seventeenth century. For the period
1700-1870, we find British per capita income growth of 0.48 per cent, broadly in line
with the widely accepted Crafts/Harley estimates. This modest trend growth in per capita
income since 1270 suggests that, working back from the present, living standards in the
late medieval period were well above âbare bones subsistenceâ. This can be reconciled
with modest levels of kilocalorie consumption per head because of the very large share of
pastoral production in agriculture
Prostate cancer treatment with Irreversible Electroporation (IRE): Safety, efficacy and clinical experience in 471 treatments.
BackgroundIrreversible Electroporation (IRE) is a novel image-guided tissue ablation technology that induces cell death via very short but strong pulsed electric fields. IRE has been shown to have preserving properties towards vessels and nerves and the extracellular matrix. This makes IRE an ideal candidate to treat prostate cancer (PCa) where other treatment modalities frequently unselectively destroy surrounding structures inducing severe side effects like incontinence or impotence. We report the retrospective assessment of 471 IRE treatments in 429 patients of all grades and stages of PCa with 6-year maximum follow-up time.Material and findingsThe patient cohort consisted of low (25), intermediate (88) and high-risk cancers (312). All had multi-parametric magnetic resonance imaging, and 199 men had additional 3D-mapping biopsy for diagnostic work-up prior to IRE. Patients were treated either focally (123), sub-whole-gland (154), whole-gland (134) or for recurrent disease (63) after previous radical prostatectomy, radiation therapy, etc. Adverse effects were mild (19.7%), moderate (3.7%) and severe (1.4%), never life-threatening. Urinary continence was preserved in all cases. IRE-induced erectile dysfunction persisted in 3% of the evaluated cases 12 months post treatment. Mean transient IIEF-5-Score reduction was 33% within 12-month post IRE follow-up and 15% after 12 months. Recurrences within the follow-up period occurred in 10% of the treated men, 23 in or adjacent to the treatment field and 18 outside the treatment field (residuals). Including residuals for worst case analysis, Kaplan Maier estimation on recurrence rate at 5 years resulted in 5.6% (CI95: 1.8-16.93) for Gleason 6, 14.6% (CI95: 8.8-23.7) for Gleason 7 and 39.5% (CI95: 23.5-61.4) for Gleason 8-10.ConclusionThe results indicate comparable efficacy of IRE to standard radical prostatectomy in terms of 5-year recurrence rates and better preservation of urogenital function, proving the safety and suitability of IRE for PCa treatment. The data also shows that IRE, besides focal therapy of early PCa, can also be used for whole-gland ablations, in patients with recurrent PCa, and as a problem-solver for local tumor control in T4-cancers not amenable to surgery and radiation therapy anymore
Monopole Planets and Galaxies
Spherical clusters of SU(2) BPS monopoles are investigated here. A large
class of monopole solutions is found using an abelian approximation, where the
clusters are spherically symmetric, although exact solutions cannot have this
symmetry precisely. Monopole clusters generalise the Bolognesi magnetic bag
solution of the same charge, but they are always larger. Selected density
profiles give structures analogous to planets of uniform density, and galaxies
with a density decaying as the inverse square of the distance from the centre.
The Bolognesi bag itself has features analogous to a black hole, and this
analogy between monopole clusters and astrophysical objects with or without
black holes in their central region is developed further. It is also shown that
certain exact, platonic monopoles of small charge have sizes and other features
consistent with what is expected for magnetic bags.Comment: 23 pages. Revised version to appear in Physical Review D. New
introduction and conclusions; analogy between monopoles and astrophysical
objects developed furthe
Quantum theory of large amplitude collective motion and the Born-Oppenheimer method
We study the quantum foundations of a theory of large amplitude collective
motion for a Hamiltonian expressed in terms of canonical variables. In previous
work the separation into slow and fast (collective and non-collective)
variables was carried out without the explicit intervention of the Born
Oppenheimer approach. The addition of the Born Oppenheimer assumption not only
provides support for the results found previously in leading approximation, but
also facilitates an extension of the theory to include an approximate
description of the fast variables and their interaction with the slow ones.
Among other corrections, one encounters the Berry vector and scalar potential.
The formalism is illustrated with the aid of some simple examples, where the
potentials in question are actually evaluated and where the accuracy of the
Born Oppenheimer approximation is tested. Variational formulations of both
Hamiltonian and Lagrangian type are described for the equations of motion for
the slow variables.Comment: 29 pages, 1 postscript figure, preprint no UPR-0085NT. Latex + epsf
styl
Coherent Vector Meson Photoproduction with Nuclear Breakup in Relativistic Heavy Ion Collisions
Relativistic heavy ions are copious sources of virtual photons. The large
photon flux gives rise to a substantial photonuclear interaction probability at
impact parameters where no hadronic interactions can occur. Multiple
photonuclear interactions in a single collision are possible. In this letter,
we use mutual Coulomb excitation of both nuclei as a tag for moderate impact
parameter collisions. We calculate the cross section for coherent vector meson
production accompanied by mutual excitation, and show that the median impact
parameter is much smaller than for untagged production. The vector meson
rapidity and transverse momentum distribution are very different from untagged
exclusive vector meson production.Comment: 14 pages, including 4 figure
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