1,028 research outputs found
Template dissolution interfacial patterning of single colloids for nanoelectrochemistry and nanosensing
Deterministic positioning and assembly of colloidal nanoparticles (NPs) onto substrates is a core requirement and a promising alternative to top-down lithography to create functional nanostructures and nanodevices with intriguing optical, electrical, and catalytic features. Capillary-assisted particle assembly (CAPA) has emerged as an attractive technique to this end, as it allows controlled and selective assembly of a wide variety of NPs onto predefined topographical templates using capillary forces. One critical issue with CAPA, however, lies in its final printing step, where high printing yields are possible only with the use of an adhesive polymer film. To address this problem, we have developed a template dissolution interfacial patterning (TDIP) technique to assemble and print single colloidal AuNP arrays onto various dielectric and conductive substrates in the absence of any adhesion layer, with printing yields higher than 98%. The TDIP approach grants direct access to the interface between the AuNP and the target surface, enabling the use of colloidal AuNPs as building blocks for practical applications. The versatile applicability of TDIP is demonstrated by the creation of direct electrical junctions for electro- and photoelectrochemistry and nanoparticle-on-mirror geometries for single-particle molecular sensing
Ordinary Percolation with Discontinuous Transitions
Percolation on a one-dimensional lattice and fractals such as the Sierpinski
gasket is typically considered to be trivial because they percolate only at
full bond density. By dressing up such lattices with small-world bonds, a novel
percolation transition with explosive cluster growth can emerge at a nontrivial
critical point. There, the usual order parameter, describing the probability of
any node to be part of the largest cluster, jumps instantly to a finite value.
Here, we provide a simple example of this transition in form of a small-world
network consisting of a one-dimensional lattice combined with a hierarchy of
long-range bonds that reveals many features of the transition in a
mathematically rigorous manner.Comment: RevTex, 5 pages, 4 eps-figs, and Mathematica Notebook as Supplement
included. Final version, with several corrections and improvements. For
related work, see http://www.physics.emory.edu/faculty/boettcher
Holographic Renormalization and Stress Tensors in New Massive Gravity
We obtain holographically renormalized boundary stress tensors with the
emphasis on a special point in the parameter space of three dimensional new
massive gravity, using the so-called Fefferman-Graham coordinates with relevant
counter terms. Through the linearized equations of motion with a standard
prescription, we also obtain correlators among these stress tensors. We argue
that the self-consistency of holographic renormalization determines counter
terms up to unphysical ambiguities. Using these renormalized stress tensors in
Fefferman-Graham coordinates, we obtain the central charges of dual CFT, and
mass and angular momentum of some black hole solutions. These results are
consistent with the previous ones obtained by other methods. In this study on
the Fefferman-Graham expansion of new massive gravity, some aspects of higher
curvature gravity are revealed.Comment: Version accepted for publication in JHEP, conclusion revised,
references adde
AdS_3/LCFT_2 - Correlators in Cosmological Topologically Massive Gravity
For cosmological topologically massive gravity at the chiral point we
calculate momentum space 2- and 3-point correlators of operators in the
postulated dual CFT on the cylinder. These operators are sourced by the bulk
and boundary gravitons. Our correlators are fully consistent with the proposal
that cosmological topologically massive gravity at the chiral point is dual to
a logarithmic CFT. In the process we give a complete classification of
normalizable and non-normalizeable left, right and logarithmic solutions to the
linearized equations of motion in global AdS_3.Comment: 39 pages + appendices, 1 eps figure, v2: minor changes in text in
4.1.2, corrected typo in (2.31
Impact of Single Links in Competitive Percolation -- How complex networks grow under competition
How a complex network is connected crucially impacts its dynamics and
function. Percolation, the transition to extensive connectedness upon gradual
addition of links, was long believed to be continuous but recent numerical
evidence on "explosive percolation" suggests that it might as well be
discontinuous if links compete for addition. Here we analyze the microscopic
mechanisms underlying discontinuous percolation processes and reveal a strong
impact of single link additions. We show that in generic competitive
percolation processes, including those displaying explosive percolation, single
links do not induce a discontinuous gap in the largest cluster size in the
thermodynamic limit. Nevertheless, our results highlight that for large finite
systems single links may still induce observable gaps because gap sizes scale
weakly algebraically with system size. Several essentially macroscopic clusters
coexist immediately before the transition, thus announcing discontinuous
percolation. These results explain how single links may drastically change
macroscopic connectivity in networks where links add competitively.Comment: non-final version, for final see Nature Physics homepag
Measurement of Exclusive B Decays to Final States Containing a Charmed Baryon
Using data collected by the CLEO detector in the Upsilon(4S) region, we
report new measurements of the exclusive decays of B mesons into final states
of the type Lambda_c^+ p-bar n(pi), where n=0,1,2,3. We find signals in modes
with one, two and three pions and an upper limit for the two body decay
Lambda_c^+ pbar. We also make the first measurements of exclusive decays of B
mesons to Sigma_c p-bar n(pi), where n=0,1,2. We find signals in modes with one
and two pions and an upper limit for the two body decay Sigma_c p-bar.
Measurements of these modes shed light on the mechanisms involved in B decays
to baryons.Comment: 11 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLNS, submitted to PR
Measurement of the Masses and Widths of the Sigma_c^++ and Sigma_c^0 Charmed Baryons
Using data recorded by the CLEO II and CLEO II.V detector configurations at
CESR, we report new measurements of the masses of the Sigma_c^{++} and
Sigma_c^0 charmed baryons, and the first measurements of their intrinsic
widths. We find M(Sigma_c^{++}) - M(Lambda_c^+) = 167.4 +- 0.1 +- 0.2 MeV,
Gamma(Sigma_c^{++}) = 2.3 +- 0.2 +- 0.3 MeV, and M(Sigma_c^0) - M(Lambda_c^+) =
167.2 +- 0.1 +- 0.2 MeV, Gamma(Sigma_c^0) = 2.5 +- 0.2 +- 0.3 MeV, where the
uncertainties are statistical and systematic, respectively.Comment: 9 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLNS, submitted to PRD, Rapid
Communications. Reference [13] correcte
The effects of tea extracts on proinflammatory signaling
BACKGROUND: Skin toxicity is a common side effect of radiotherapy for solid tumors. Its management can cause treatment gaps and thus can impair cancer treatment. At present, in many countries no standard recommendation for treatment of skin during radiotherapy exists. In this study, we explored the effect of topically-applied tea extracts on the duration of radiation-induced skin toxicity. We investigated the underlying molecular mechanisms and compared effects of tea extracts with the effects of epigallocatechin-gallate, the proposed most-active moiety of green tea. METHODS: Data from 60 patients with cancer of the head and neck or pelvic region topically treated with green or black tea extracts were analyzed retrospectively. Tea extracts were compared for their ability to modulate IL-1β, IL-6, IL-8, TNFα and PGE(2 )release from human monocytes. Effects of tea extracts on 26S proteasome function were assessed. NF-κB activity was monitored by EMSAs. Viability and radiation response of macrophages after exposure to tea extracts was measured by MTT assays. RESULTS: Tea extracts supported the restitution of skin integrity. Tea extracts inhibited proteasome function and suppressed cytokine release. NF-κB activity was altered by tea extracts in a complex, caspase-dependent manner, which differed from the effects of epigallocatechin-gallate. Additionally, both tea extracts, as well as epigallocatechin-gallate, slightly protected macrophages from ionizing radiation CONCLUSION: Tea extracts are an efficient, broadly available treatment option for patients suffering from acute radiation-induced skin toxicity. The molecular mechanisms underlying the beneficial effects are complex, and most likely not exclusively dependent on effects of tea polyphenols such as epigallocatechin-gallate
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