1,564 research outputs found
Contacting single bundles of carbon nanotubes with alternating electric fields
Single bundles of carbon nanotubes have been selectively deposited from
suspensions onto sub-micron electrodes with alternating electric fields. We
explore the resulting contacts using several solvents and delineate the
differences between Au and Ag as electrode materials. Alignment of the bundles
between electrodes occurs at frequencies above 1 kHz. Control over the number
of trapped bundles is achieved by choosing an electrode material which
interacts strongly with the chemical functional groups of the carbon nanotubes,
with superior contacts being formed with Ag electrodes.Comment: 4 pages, RevTe
Reconstruction methods for acoustic particle detection in the deep sea using clusters of hydrophones
This article focuses on techniques for acoustic noise reduction, signal
filters and source reconstruction. For noise reduction, bandpass filters and
cross correlations are found to be efficient and fast ways to improve the
signal to noise ratio and identify a possible neutrino-induced acoustic signal.
The reconstruction of the position of an acoustic point source in the sea is
performed by using small-volume clusters of hydrophones (about 1 cubic meter)
for direction reconstruction by a beamforming algorithm. The directional
information from a number of such clusters allows for position reconstruction.
The algorithms for data filtering, direction and position reconstruction are
explained and demonstrated using simulated data.Comment: 7 pages, 13 figure
Potential Neutrino Signals from Galactic Gamma-Ray Sources
The recent progress made in Galactic gamma-ray astronomy using the High
Energy Stereoskopic System (H.E.S.S.) instrument provides for the first time a
population of Galactic TeV gamma-rays, and hence potential neutrino sources,
for which the neutrino flux can be estimated. Using the energy spectra and
source morphologies measured by H.E.S.S., together with new parameterisations
of pion production and decay in hadronic interactions, we estimate the signal
and background rates expected for these sources in a first-generation water
Cherenkov detector (ANTARES) and a next-generation neutrino telescope in the
Mediterranean Sea, KM3NeT, with an instrumented volume of 1 km^3. We find that
the brightest gamma-ray sources produce neutrino rates above 1 TeV, comparable
to the background from atmospheric neutrinos. The expected event rates of the
brightest sources in the ANTARES detector make a detection unlikely. However,
for a 1 km^3 KM3NeT detector, event rates of a few neutrinos per year from
these sources are expected, and the detection of individual sources seems
possible. Although generally these estimates should be taken as flux upper
limits, we discuss the conditions and type of gamma-ray sources for which the
neutrino flux predictions can be considered robust.Comment: 20 pages, 4 figures; v2: ERROR in energy scale of KM3NeT effective
neutrino area corrected which resulted in event rates being about a factor 3
too low; v3: grammatical changes and update of references after receiving
proof
Normal origamis of Mumford curves
An origami (also known as square-tiled surface) is a Riemann surface covering
a torus with at most one branch point. Lifting two generators of the
fundamental group of the punctured torus decomposes the surface into finitely
many unit squares. By varying the complex structure of the torus one obtains
easily accessible examples of Teichm\"uller curves in the moduli space of
Riemann surfaces. The p-adic analogues of Riemann surfaces are Mumford curves.
A p-adic origami is defined as a covering of Mumford curves with at most one
branch point, where the bottom curve has genus one. A classification of all
normal non-trivial p-adic origamis is presented and used to calculate some
invariants. These can be used to describe p-adic origamis in terms of glueing
squares.Comment: 21 pages, to appear in manuscripta mathematica (Springer
DEK Regulates Hematopoietic Stem Engraftment and Progenitor Cell Proliferation
DEK is a biochemically distinct protein that is generally found in the nucleus, where it is vital to global heterochromatin integrity. However, DEK is also secreted by cells (eg, macrophages) and influences other adjacent cells (eg, acts as a chemoattractant for certain mature blood cells). We hypothesized that DEK may modulate functions of hematopoietic stem (HSCs) and progenitor (HPCs) cells. C57Bl/6 mice were used to demonstrate that absolute numbers and cycling status of HPCs (colony forming unit-granulocyte macrophage [CFU-GM], burst forming unit-erythroid [BFU-E], and colony forming unit-granulocyte erythroid macrophage megakaryocyte [CFU-GEMM]) in bone marrow (BM) and spleen were significantly enhanced in DEK -/- as compared with wild-type (WT) control mice. Moreover, purified recombinant DEK protein inhibited colony formation in vitro by CFU-GM, BFU-E, and CFU-GEMM from WT BM cells and human cord blood (CB) cells in a dose-dependent fashion, demonstrating that DEK plays a negative role in HPC proliferation in vitro and in vivo. Suppression was direct acting as determined by inhibition of proliferation of single isolated CD34+ CB cells in vitro. In contrast, DEK -/- BM cells significantly demonstrated reduced long term competitive and secondary mouse repopulating HSC capacity compared with WT BM cells, demonstrating that DEK positively regulates engrafting capability of self-renewing HSCs. This demonstrates that DEK has potent effects on HSCs, HPCs, and hematopoiesis, information of biological and potential clinical interest.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90478/1/scd-2E2011-2E0451.pd
FeijĂŁo comum: caracterĂsticas morfo-agronĂ´micas de cultivares.
O presente trabalho objetivou avaliar as caracterĂsticas morfoagronĂ´micas de cultivares de feijĂŁo comum de diversos grupos comerciais na Ă©poca de safrinha
Componentes produtivos de cultivares de feijĂŁo comum em cultivo safrinha.
O presente trabalho teve por objetivo avaliar os componentes produtivos de cultivares de feijĂŁo comum de diversos grupos comerciais na Ă©poca de safrinha
Uncertainty about the impact of social decisions increases prosocial behaviour
Uncertainty about how our choices will affect others infuses social life. Past research suggests uncertainty has a negative effect on prosocialbehaviour by enabling people to adopt self-serving narratives about their actions. We show that uncertainty does not always promote selfishness. We introduce a distinction between two types of uncertainty that have opposite effects on prosocial behaviour. Previous work focused on outcome uncertainty (uncertainty about whether or not a decision will lead to a particular outcome). However, as soon as people’s decisions might have negative consequences for others, there is also impact uncertainty (uncertainty about how others’ well-being will be impacted by the negative outcome). Consistent with past research, we found decreased prosocial behaviour under outcome uncertainty. In contrast, prosocial behaviour was increased under impact uncertainty in incentivized economic decisions and hypothetical decisions about infectious disease threats. Perceptions of social norms paralleled the behavioural effects. The effect of impact uncertainty on prosocial behaviour did not depend on the individuation of others or the mere mention of harm, and was stronger when impact uncertainty was made more salient. Our findings offer insights into communicating uncertainty, especially in contexts where prosocial behaviour is paramount, such as responding to infectious disease threats
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