1,046 research outputs found
Local solid-state modification of nanopore surface charges
The last decade, nanopores have emerged as a new and interesting tool for the
study of biological macromolecules like proteins and DNA. While biological
pores, especially alpha-hemolysin, have been promising for the detection of
DNA, their poor chemical stability limits their use. For this reason,
researchers are trying to mimic their behaviour using more stable, solid-state
nanopores. The most successful tools to fabricate such nanopores use high
energy electron or ions beams to drill or reshape holes in very thin membranes.
While the resolution of these methods can be very good, they require tools that
are not commonly available and tend to damage and charge the nanopore surface.
In this work, we show nanopores that have been fabricated using standard
micromachning techniques together with EBID, and present a simple model that is
used to estimate the surface charge. The results show that EBID with a silicon
oxide precursor can be used to tune the nanopore surface and that the surface
charge is stable over a wide range of concentrations.Comment: 10 pages, 6 figure
Results from the test bench of the Geometry Monitoring System of the ALICE Muon Spectrometer
We present the results obtained with the test bench of the Geometry Monitoring System (GMS) for the ALICE Muon Spectrometer. It consists in a mock up, reproducing at full scale, three half planes of the chambers 6, 7 and 8 of the spectrometer. We show that the GMS is able to measure transverse displacements with an accuracy of 1.5 microm. We show also that the resolution deteriorates by a factor 3 to 4 when thermal gradients are generated
How Trade and Investment Agreements Affect Bilateral Foreign Direct Investment: Results from a Structural Gravity Model
The paper develops a new stand-alone structural gravity model for explaining bilateral FDI patterns. We employ the model to analyse the impact of preferential trade agreements (PTAs), bilateral investment treaties (BITs) and other policies on bilateral foreign direct investment (FDI). We use the UNCTAD global database on bilateral FDI stocks and flows. To control for the heterogeneous nature of PTAs, we employ two different indicators of PTA depth. We find that on average signing a PTA increases bilateral FDI stocks by around 30%. Nevertheless, we also find that âdeeperâ or comprehensive PTAs (e.g., including provisions on investment, public procurement and intellectual property rights provisions) do not have a significantly different impact than signing regular PTAs. Belonging to the EU single market, on the other hand, has a strong impact and increases bilateral FDI by around 135%, and signing a BIT has an effect that is comparable to signing a PTA
G Electronics and Data Acquisition (Forward-Angle Measurements)
The G parity-violation experiment at Jefferson Lab (Newport News, VA) is
designed to determine the contribution of strange/anti-strange quark pairs to
the intrinsic properties of the proton. In the forward-angle part of the
experiment, the asymmetry in the cross section was measured for
elastic scattering by counting the recoil protons corresponding to the two
beam-helicity states. Due to the high accuracy required on the asymmetry, the
G experiment was based on a custom experimental setup with its own
associated electronics and data acquisition (DAQ) system. Highly specialized
time-encoding electronics provided time-of-flight spectra for each detector for
each helicity state. More conventional electronics was used for monitoring
(mainly FastBus). The time-encoding electronics and the DAQ system have been
designed to handle events at a mean rate of 2 MHz per detector with low
deadtime and to minimize helicity-correlated systematic errors. In this paper,
we outline the general architecture and the main features of the electronics
and the DAQ system dedicated to G forward-angle measurements.Comment: 35 pages. 17 figures. This article is to be submitted to NIM section
A. It has been written with Latex using \documentclass{elsart}. Nuclear
Instruments and Methods in Physics Research Section A: Accelerators,
Spectrometers, Detectors and Associated Equipment In Press (2007
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