5,477 research outputs found
Metal contacts to lowly doped Si and ultra thin SOI
We present our investigations on the fabrication of ohmic and Schottky contacts of several metals on lowly doped bulk Si and SOI wafers. Through this paper we evaluate the fabrication of rectifying devices in which no doping is intentionally introduced
Fabrication and characterization of the charge-plasma diode
We present a new lateral Schottky-based rectifier called the charge-plasma diode realized on ultrathin silicon-oninsulator. The device utilizes the workfunction difference between two metal contacts, palladium and erbium, and the silicon body. We demonstrate that the proposed device provides a low and constant reverse leakage-current density of about 1 fA/ÎŒm with ON/OFF current ratios of around 107 at 1-V forward bias and room temperature. In the forward mode, a current swing of 88 mV/dec is obtained, which is reduced to 68 mV/dec by back-gate biasing
Analysis of the entanglement between two individual atoms using global Raman rotations
Making use of the Rydberg blockade, we generate entanglement between two
atoms individually trapped in two optical tweezers. In this paper we detail the
analysis of the data and show that we can determine the amount of entanglement
between the atoms in the presence of atom losses during the entangling
sequence. Our model takes into account states outside the qubit basis and
allows us to perform a partial reconstruction of the density matrix describing
the two atom state. With this method we extract the amount of entanglement
between pairs of atoms still trapped after the entangling sequence and measure
the fidelity with respect to the expected Bell state. We find a fidelity
for the 62% of atom pairs remaining in the traps at
the end of the entangling sequence
Influence of the head model on EEG and MEG source connectivity analysis
The results of brain connectivity analysis using reconstructed source time courses derived from EEG and MEG data depend on a number of algorithmic choices. While previous studies have investigated the influence of the choice of source estimation method or connectivity measure, the effects of the head modeling errors or simplifications have not been studied sufficiently. In the present simulation study, we investigated the influence of particular properties of the head model on the reconstructed source time courses as well as on source connectivity analysis in EEG and MEG. Therefore, we constructed a realistic head model and applied the finite element method to solve the EEG and MEG forward problem. We considered the distinction between white and gray matter, the distinction between compact and spongy bone, the inclusion of a cerebrospinal fluid (CSF) compartment, and the reduction to a simple 3-layer model comprising only skin, skull, and brain. Source time courses were reconstructed using a beamforming approach and the source connectivity was estimated by the imaginary coherence (ICoh) and the generalized partial directed coherence (GPDC). Our results show that in both EEG and MEG, neglecting the white and gray matter distinction or the CSF causes considerable errors in reconstructed source time courses and connectivity analysis, while the distinction between spongy and compact bone is just of minor relevance, provided that an adequate skull conductivity value is used. Large inverse and connectivity errors are found in the same regions that show large topography errors in the forward solution. Moreover, we demonstrate that the very conservative ICoh is relatively safe from the crosstalk effects caused by imperfect head models, as opposed to the GPDC
Entanglement of two individual neutral atoms using Rydberg blockade
We report the generation of entanglement between two individual Rb
atoms in hyperfine ground states and which are held in
two optical tweezers separated by 4 m. Our scheme relies on the Rydberg
blockade effect which prevents the simultaneous excitation of the two atoms to
a Rydberg state. The entangled state is generated in about 200 ns using pulsed
two-photon excitation. We quantify the entanglement by applying global Raman
rotations on both atoms. We measure that 61% of the initial pairs of atoms are
still present at the end of the entangling sequence. These pairs are in the
target entangled state with a fidelity of 0.75.Comment: text revised, with additional reference
Stigma development in Nicotiana tabacum. Cell death in transgenic plants as a marker to follow cell fate at high resolution
Entanglement of two individual atoms using the Rydberg blockade
We report on our recent progress on the manipulation of single rubidium atoms
trapped in optical tweezers and the generation of entanglement between two
atoms, each individually trapped in neighboring tweezers. To create an
entangled state of two atoms in their ground states, we make use of the Rydberg
blockade mechanism. The degree of entanglement is measured using global
rotations of the internal states of both atoms. Such internal state rotations
on a single atom are demonstrated with a high fidelity.Comment: Proceeding of the 19th International Conference on Laser Spectroscopy
ICOLS 2009, 7-13 June 2009, Hokkaido, Japa
Influence of anisotropic conductivity of the white matter tissue on EEG source reconstruction a FEM simulation study
The aim of this study was to quantify the influence of the inclusion of anisotropic conductivity on EEG source reconstruction. We applied high-resolution finite element modeling and performed forward and inverse simulation with over 4000 single dipoles placed around an anisotropic volume block (with an anisotropic ratio of 1:10) in a rabbit brain. We investigated three different orientation of the dipoles with respect to the anisotropy in the white matter block. We found a weak influence of the anisotropy in the forward simulation on the electric potential. The relative difference measure (RDM) between the potentials simulated with and without taking into account anisotropy was less than 0.009. The changes in magnitude (MAG) ranged from 0.944 to 1.036. Using the potentials of the forward simulation derived with the anisotropic model and performing source reconstruction by employing the isotropic model led to dipole shifts of up to 2 mm, however the mean shift over all dipoles and orientations of 0.05 mm was smaller than the grid size of the FEM model (0.6 mm). However, we found the source strength estimation to be more influenced by the anisotropy (up to 7-times magnified dipole strength)
Continuous Krapcho Dealkoxycarbonylation in API Synthesis
A high pressure and high temperature continuous flow reactor has been used to intensify a Krapcho dealkoxycarbonylation
reaction in the context of API synthesis. The reactor enables operation of the reaction above temperatures
possible in batch and thus significantly increased conversion rates are achieved. Also a broader choice of solvents is
possible by the use of the continuous process. Batch and continuous reaction are compared in terms of operation range
and space-time-yield. Despite lower concentrations of the reactants in the continuous process, space-time-yield exceeds
that of the batch process by more than an order of magnitude due to the higher reaction rates
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